Research ArticleCross-Trained Worker Assignment Problem in CellularManufacturing System Using Swarm Intelligence Metaheuristics
LangWu Fulin Cai Li Li and Xianghua Chu
College of Management Shenzhen University Shenzhen China
Correspondence should be addressed to Xianghua Chu xchuszueducn
Received 12 May 2018 Accepted 22 October 2018 Published 4 November 2018
Academic Editor Oliver Schutze
Copyright copy 2018 LangWu et alThis is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
Cross-trained worker assignment has become increasingly important for manufacturing efficiency and flexibility in cellularmanufacturing system because of the recent increase in labor cost Researchers mainly focused on assigning skilled workers totasks for favorable capacity or cost However few of them have recognized the need for skill level enhancement through cross-training to avoid excessive training especially for workload balance across multiple cells This study presents a new mathematicalprogramming model aimed at minimum training and maximum workload balance with economical labor utilization to addressthe worker assignment problem with a cross-training plan spanning multiple cells The model considers the trade-off betweentraining expenditure and workload balance to achieve a more flexible solution based on decision-makerrsquos preference Consideringthe computational complexity of the problem the classical swarm intelligence optimizers ie particle swarm optimization (PSO)and artificial bee colony (ABC) are implemented to search the problem landscape To improve the optimization performancea superior tracking ABC with an augmented information sharing strategy is designed to address the problem Ten benchmarkproblems are employed for numerical experiments The results indicate the efficiency and effectiveness of the proposed models aswell as the developed algorithms
1 Introduction
Following the recent emerging Industrial Revolution 40many manufacturers are engaged in finding new ways toincrease the productivity and flexibility of their manufactur-ing systems so they can cope with varied production envi-ronments such as multiproduct and small-batch productionOne of such solutions is to use cellular manufacturing sys-tem (CMS) which implements group technology to classifyfamilies of parts produced and allocate machine groups topart families CMS is a hybrid system that highlights thestrengths of job shop (flexibility in producing a wide varietyof products) and flow line (efficient flow and high productionrate) [1]
Previous studies on CMS have mainly focused on thecell formation problem which refers to the technology offorming appropriate part families and their correspondingmachine groups [2ndash4] However CMS includes not onlyparts and machines but also groups of tasks and workersOwing to the rapid increase in labor cost recently the
assignment of suitable workers to handle various tasks ineach manufacturing cell becomes an important factor in theimplementation of CMS
CMS comprises multiple manufacturing cells where eachcell includes multiple tasks in real-world manufacturingsituation Each worker is proficient in one or more skills atdifferent levels The standard task time is fixed generally Inpractice the actual task time varies due to the differencesof the skill levels of the workers Mutlu et al [5] noted thatskill types and skill levels of workers should be consideredduring worker assignment Cross-training can assist workersin obtaining more skills and enhance their skill levels Cross-trained workers are more flexible than specialized workerssince there is more opportunity to balance workload andrelieve overloaded stress among workers though there wouldbe significant additional costs to train multifunctional work-ers [6] The question is to what extent should the labor forcebe cross-trained And more precisely who should be cross-trained for which machine or task [7] This raises furtherquestions such as how to assign the cross-trained workers
HindawiMathematical Problems in EngineeringVolume 2018 Article ID 4302062 15 pageshttpsdoiorg10115520184302062
2 Mathematical Problems in Engineering
to various tasks so as to optimize some output measure[8] In previous studies the cross-training problem and theworker assignment problem were always handled separatelyHowever the associated trade-offs between the two problemshave not been answered yet In this study we aim to proposea framework to solve the worker assignment problem in CMSincorporating cross-training
A major challenge arising in this context concerns theprinciple of cross-trained worker assignment in CMS whereworker-task configuration among multiple cells is exploredbased on customer demand to seek workload balance ofassigned workers with minimum cross-training and laborcost Specifically two questions should be answered(1) Which worker should be assigned to which task in
multiple manufacturing cells(2)Which worker should be trained to reach which skill
level for the assigned task in multiple manufacturing cellsPrevious studies related to the above questions mainly
have two limitations (1) They only answered the firstquestion by assuming that the skill levels of workers arefixed while neglecting the need for skill level enhancementvia cross-training Skill level enhancement denotes that theassigned worker should be trained not only for higher effi-ciency in its existing skills but also for the acquisition of newskills And (2) they mainly paid attention to flow-line systemor a single manufacturing cell and ignored the complexinteraction among multiple cells during cross-trained workerassignment in CMS
To address this gap this paper presents a novel mathe-matical programming model that aims to minimize trainingcost workload imbalance and the number of assignedworkers based on customer demand The proposed modelnot only takes into account the problem of cross-trainedworker assignment for multiple cells but also determinesthe training requirements considering the trade-off betweentraining expenditure and workload balance in the followingscenarios(1) Training is recommended strongly for more exact
workload balance which results in more expenditure(2) Training is not recommended for less expenditure
which results in less exact workload balanceIn view of the complexity and computational burden
of the presented model we implement swarm intelligenceoptimizers for the global optimization Swarm intelligence(SI) algorithms motivated by collective behaviors in naturalsystem have achieved great successful applications in var-ious areas [9 10] As a result a number of swarm-basedmetaheuristics have been developed recently among whichparticle swarm optimization (PSO) [11] and artificial beecolony (ABC) [12] are two representative algorithms PSOwas proposed for global optimization by emulating the veloc-ity adjusting of fish schooling and bird flocking ABC wasdeveloped by simulating the information exchange throughbee dancing PSO and ABC have shown high efficiencyand effectiveness in solving real-world global optimizationproblems [9] In this study the global topology PSO (GPSO)local topology PSO (LPSO) and ABC are implementedto solve the proposed cross-trained worker assignment inCMS To improve the optimization performance a superior
tracking artificial bee colony (STABC) with an augmentedinformation sharing strategy is developed In STABC thereare two main contributions compared to the canonical ABC(1) instead of learning one dimension from neighbors inSTABC a bee can learn from others in all dimensions (2)instead of chasing the random individual in STABC eachbee either learns from its previous information or movetowards other superior bees Computational experiments andcomparisons are conducted to evaluate the efficiency of theswarm intelligence algorithms
Comparing with the previous research the contributionof this study lies in three aspects(1) A new model is presented to solve the worker assign-
ment problem formultiplemanufacturing cells incorporatingcross-training planning(2)The skill enhancement is integrated to avoid excessive
training and the trade-off between training expenditureand workload balance is combined to obtain more flexiblesolution in the model(3) Swarm intelligence optimizers are developed and
improved to solve the proposed mathematical model effi-ciently
Remainder of this paper is organized as follows Section 2reviews the literaturerelating to worker assignment Section 3presentsmodel for effective cross-trainedworker assignmentSection 4 describes the swarm intelligence metaheuristicsused and the algorithmic implementation for solving theproblem Section 5 describes experiments with computa-tional results to justify the proposed model and algorithmsSection 6 summarizes the conclusions and future researchdirections
2 Literature Review
Theapproaches regarding theworker assignment problemarebriefly reviewed in this sectionThe literature can be classifiedby considering two types ofmanufacturing systems flow-linemanufacturing system (FLMS) and cellular manufacturingsystem (CMS) The limitations in previous studies are sum-marized for the motivation of our work
21 Worker Assignment in Flow-Line Manufacturing SystemHopp et al [13] considered two cross-training strategiescherry picking and skill chain In zoned work sharing somemachinestasks on the line are shared between workers toseek capacity balance Inman et al [6] argued that cross-training should be used judiciously since it is costly and islimited by learning capacity and can confound the searchfor quality problems They presented a training strategycalled chaining in which workers are trained to perform asecond task and the assignments of task types to workersare linked in a chain Their research has shown that cross-training in chaining is a practical and effective strategy tocompensate for absenteeism on assembly lines Moreira etal [14] proposed simple heuristics for solving the assemblyline worker assignment and balancing problem Their ideawas to use task and worker priority rules to define whichworker and which set of tasks should be assigned to each
Mathematical Problems in Engineering 3
workstation by constructive heuristic framework Parvin etal [15] introduced a new canonical model of worker cross-training called a Fixed Task Zone Chain A new heuris-tic worker control policy was presented to design a zonestructure that can be balanced by assigning worker to workstation based on his or her skill set for maximum throughputMutlu et al [5] solved the assembly line worker assignmentand balancing problem when task times differ depending onoperator skills and concerns with the assignment of tasks andoperators to stations in order to minimize the cycle timeSaidi-Mehrabad et al [16] presented a novel integer linearprogramming model for dynamic manufacturing systems inthe presence of system configurations worker assignmentand production plan for each part type at each period Theobjective of worker assignment is to minimize training andsalary of worker costs Sungur and Yavuz [17] consideredqualification requirements and levels of workers to achieveassembly line balance and worker assignment problem Theysuggested that the workers should be ranked hierarchicallyaccording to their qualification requirements and levelsFrom the standpoint of the paper a higher qualified workerimplies a higher cost and lower process time
22 Worker Assignment in Cellular Manufacturing SystemThe proposed strategies of worker assignment in CMS canbe divided into two categories (1) simultaneous formation ofmanufacturing cells and worker assignment and (2) assign-ment of workers to cells after cell formation
221 Simultaneous Formation of Manufacturing Cells andWorker Assignment The strategy of forming manufacturingcells and worker assignment simultaneously was achievedfirst by Aryanezhad et al [18] The first part of the modelobjective function proposed in their study sought to mini-mize production cost intercell material handling cost andmachine costs in the planning horizon The second partinvolved human issues including hiring cost firing costtraining cost and salary into worker assignment in cellsHowever this study ignored efficiency of workersrsquo skills indifferent tasks Mahdavi et al [19] determined optimal cellconfigurations worker assignments and process plans usingan integer mathematical programming model The purposewas to minimize holding and backorder intercell materialhandling machine and reconfiguration and workers hiringfiring and salary costs Their model was solved by branch-and-bound (BampB)method using Lingo 80 softwareMahdaviet al [20] presented a fuzzy goal programming for groupingmachines parts and workers simultaneously and determin-ing production planning in dynamic virtual CMS Theirmodel aimed to minimize inventory holding and backordercosts as well as the number of exceptional elements in a cubicspace of machine-part-worker incidence matrix under con-straints of machine capacity worker capacity and customerdemand Bagheri and Bashiri [21] proposed a mathematicalmodel to simultaneously solve the cell formation operatorassignment and intercell layout problems Salary hiringfiring and training cost were considered while optimizing
worker assignment Their results indicated that consider-ation of the operator assignment problem has significantimpact on the overall system efficiency Niakan et al [22]proposed a new biobjective mathematical model to solvedynamic cell formation and skill-based worker assignmentproblem Environmental and social criteria were consideredin their research Due to the NP-hardness of the problemthey merged an efficient hybrid metaheuristic based on thenondominated sorting genetic algorithm with multiobjectivesimulated annealing Liu et al [1] built an integrated modelto solve the problems of machine grouping part schedulingworker assignment for minimizing material handling costsand the fixed and operating costs of machines and workersThey also developed a discrete bacteria foraging algorithmcombining with priority rule based parallel schedule gener-ation scheme for the intractable model Liu et al [23] builtanother integrated model to solve worker assignment andproduction planning problem again for CMS In the newmodel they assumed that all workers had the characteristicsof learning or forgetting
222 Assignment of Workers to Cells after Cell FormationMore previous studies focused on the problem of assigningworkers to tasks in cells after cell formation Askin andHuang[24] presented a mixed integer goal programming modelfor solving the worker assignment problem and coming upwith a training plan for technical and administrative skillsThemodel aimed to maximize team synergy between workerabilities and task requirements while minimizing trainingcost Greedy heuristic filtered beam search and simulatedannealing techniques were developed and tested to solve theproblem Norman et al [25] considered productivity outputquality and training costs in assigning workers to manufac-turing cells with the objective of maximizing the effectivenessof the organization Comparing with traditional workerassignments the model in their research did not include notonly technical skills but also human skills Ertay and Ruan[26] noted a data envelopment analysis to determine themost efficient number of operators and efficientmeasurementof labor assignment in CMS Fitzpatrick and Askin [27])developedmathematical models for forming effective humanteams by selecting suitable interpersonal construction andconsidering technical skill requirements from initial laborpools Meanwhile extensive cross-training policies were alsoattained to optimize team performance and a balancedplacement heuristic was proposed and evaluated Cesani andSteudel [28] simultaneously considered concepts of workloadsharing workload balancing and the presence of bottleneckoperations to classify labor strategies according to type ofmachine-operator assignments including dedicated sharedand combined assignment Simulation modeling was usedto test suitability of these concepts in an actual cell imple-mentation Suer and Tummaluri [7] developed mathematicalmodels to tackle three problems finding alternative cellconfigurations loading cells and finding crew sizes andassigning operators to operations They also proposed twoheuristic approaches for operator assignment McDonald etal [29] presented a mathematical model to solve the worker
4 Mathematical Problems in Engineering
assignment arising in a lean manufacturing cell The modelsought minimum cost of training inventory and poor qualityto determine skill training necessary for workers to meettasks and customer demand Their study also proposed theaddition of pay-for-skills reward in evaluating the costs andbenefits of cross-training However their study had onlyfocused on worker assignment for a single cell althoughmultiple cells exist in the CMS Murali et al [30] developedan artificial neural network model for assigning workforce invirtual cells under dual resource constrained context wherethe number of available workers is less than total numberof available machines Egilmez et al [31] developed a four-phased hierarchical methodology to address the stochasticskill-based manpower allocation problem In their studyworkerrsquos expected processing time and the standard deviationfor each operation were considered individually to optimizethe worker assignment to cells and maximize the productionrate of manufacturing system Table 1 presents a classificationof the previous studies
The aforementioned studies had pointed out that workerassignment plays an essential role in both flow-line andcellular manufacturing system To explore the problemof workload balance among assigned workers the cross-training strategy has been examined widely However mostof previous studies just determined which worker shouldbe trained for which task The question of an effectivestrategy of need for cross-training by prioritizing exact skilllevel of worker to avoid excessive training was ignoredThat is very few achievements specifically indicated howmany workers and in which skills they should be trained towhich level with minimum training and labor cost as wellas maximum workload balance Moreover the question oftrade-off between training expenditure andworkload balancecould lead to more flexible worker assignment and cross-training policies which did not attract significant interestin previous study Besides for the question of balancingworkload of assigned workers during cross-trained workerassignment most of previous studies paid attention to flow-line manufacturing system or a single manufacturing cellThe solution of this question formultiple manufacturing cellsshould receive more concern because it is more complex andpractical due to the interplay among cells
Considering the high complexity of the NP-hard prob-lem optimization software (LINGO CPLEX) were accompa-nied with long runtime consumption Consequently efficientmetaheuristics for the models have been attracting growingattention in recent years especially swarm intelligence meta-heuristics For example ABC was employed to address theuncovering community problem in complex networks [42]and a novel PSO algorithm was utilized for power systemoptimization [43] However few researchers used the swarmintelligence metaheuristics to solve the problem of cross-trained worker assignment for multiple cells
To fill the gaps in the literature this study aimsto build a new model to address the worker assign-ment problem among multiple manufacturing cells whileincorporating cross-training planning for workload balanceand develop solutions based on the swarm intelligencealgorithms
3 Proposed Model for Cross-TrainedWorker Assignment
This section elaborates the mathematical model for theproblem of cross-trained worker assignment in CMS Weassume that part families have already been formed andthe machines have been allocated to each part family Thetype of manufacturing cell is considered a divisional cellwhere tasks are divided among several workers in accordancewith their skill levels and task time Workers cooperate andshuttle among the workstations to complete one or severaldiscrete or successive tasks [44] Based on the feature ofcellular manufacturing system several part types with similaroperations form a part family which are processed by a groupof machines and workers in each manufacturing cell Thatmeans tasks for processing different part types in a cell aresimilar In this paper we consider skill as workerrsquos capabilityon assigned task including machine and hand operationsSome other operational assumptions and statements arestated as follows
(i) The initial skill level of each worker is given(ii)The processing time for each task for each part type is
known(iii) Each worker is assigned just to one cell(iv) Each task is assigned just to one worker(v) Machine breakdown and absenteeism are not consid-
ered(vi) All materials are delivered on time(vii) Training time is not considered(viii) The training cost of each worker for each task
depends on the task type and the skill level but not on the parttypes For instance part types 1 and 2 include task 1 which ishandled by worker 1 in a cell Training cost of worker 1 justdepends on task 1 but not on the part type
(ix) Each worker can handle all part types that arrive athis or her task stations
31 Model Notations Table 2 summarizes the index setsparameters and variables used in the proposed model
32 Mathematical Formulation The cross-trained workerassignment problem for multiple cells in CMS can be for-mulated as a nonlinear 0ndash1 integer programming model asfollows
119872119894119899 = 1205871 lowast119862
sum119888=1
119870
sum119896=1
119869
sum119895=1
119871
sum119897=1
(119908119897 minus119882119896119895) lowast 119879119862119895 lowast 119885119888119896119897119895 (1)
+1205872 lowast 120572 lowast119862
sum119888=1
119882119861119888 lowast sum119870119896=1119873119888119896sum119870119896=1119882119871119896 lowast 119873119888119896
(2)
+119862
sum119888=1
119870
sum119896=1
119873119888119896 lowast119872 (3)
subject to119870
sum119896=1
119910119888119896119895 = 1 for forall119888 119895 satisfying119875
sum119901=1
119879119888119901119895 gt 0 (4)
Mathematical Problems in Engineering 5
Table1Th
eclassificatio
nof
relatedliterature
Author
Manufacturin
gsystem
type
Num
bero
fcells
Skill
level
Cross-T
raining
Workloadbalance
Datan
ature
Solvingmetho
dHop
petal[13]
FLMS
radicradic
Stochastic
Heuris
ticPo
licies
Inman
etal[6]
FLMS
radicStochastic
Simulation
Moreira
etal[14]
FLMS
radicCertain
HGA
Mutluetal[5]
FLMS
radicCertain
IGA
Saidi-M
ehrabadetal[16]
FLMS
radicradic
Stochastic
LINGO
Sung
urandYavu
zetal[17]
FLMS
radicCertain
CPLE
XParvin
etal[15]
FLMS
radicradic
Stochastic
Heuris
ticPo
licies
Aryanezhadetal[18]
CMS
Multip
leradic
radicCertain
LINGO
Mahdavietal[19]
CMS
Multip
leCertain
LINGO
Mahdavietal[20]
CMS
Multip
leCertain
LINGO
Bagh
eriand
Bashiri
[32]
CMS
Multip
leradic
Stochastic
LINGO
Niakanetal[22]
CMS
Multip
leradic
radicStochastic
NSG
AII-
MOSA
Liuetal[1]
CMS
Multip
leStochastic
DBF
ALiuetal[23]
CMS
Multip
leradic
Certain
HBF
AAskin
andHuang
[24]
CMS
Multip
leradic
radicStochastic
Greedyheuristic
Norman
etal[25]
CMS
Sing
leradic
radicStochastic
CPLE
XErtayandRu
an[26]
CMS
Sing
leStochastic
DEA
FitzpatrickandAskin
[27]
CMS
Sing
leradic
Stochastic
Balanced
placem
enth
euris
ticCesaniand
Steudel[28]
CMS
Sing
leradic
Certain
Simulation
Suer
andTu
mmaluri[33]
CMS
Sing
leradic
Stochastic
Max
andMaxMin
heuristic
McD
onaldetal[29]
CMS
Sing
leradic
radicCertain
CPLE
XMuralietal[30]
CMS
Multip
leradic
radicCertain
ANN
Egilm
ezetal[31]
CMS
Multip
leradic
Certain
LINGO
6 Mathematical Problems in Engineering
Table 2 Model notations and definitions
Index sets Definitions119888 Index of cells (119888 = 1 2 119862)119901 Index of parts (119901 = 1 2 119875)119895 Index of tasks (119895 = 1 2 119869)119896 Index of workers (119896 = 1 2 119870)119897 Index of skill levels (119897 = 1 2 119871)Parameters Definitions119862 Number of cells119875 Number of parts119869 Number of tasks119870 Number of workers119871 Number of skill levels119879119862119895 Training cost of task 119895119879119888119901119895 Standard processing time of part type 119901 at task 119895 in cell 119888119889119888119901119895 Required throughput of part type 119901 at task 119895 in cell 119888 in one shift119882119896119895 Initial skill level weight of worker k at task 119895119908119897 Weight of skill level 119897119867 Available working time in one shift119881 Maximum permissible training cost120572 Penalty cost of workload imbalance119872 Large value1205871 1205872 Weight factorsVariables Definitions119885119888119896119897119895 1 if worker k with skill level l will be assigned to task j in cell c 0 otherwise119910119888119896119895 1 if worker k will be assigned to task j in cell c 0 otherwise119873119888119896 1 if worker k will be assigned into cell c 0 otherwise119882119871119896 Workload of worker k119882119861119888 Workload of bottleneck worker in cell c
119870
sum119896=1
119910119888119896119895 = 0 for forall119888 119895 satisfying119875
sum119901=1
119879119888119901119895 = 0 (5)
119873119888119896 = 1 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 ge 1 (6)
119873119888119896 = 0 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 = 0 (7)
119862
sum119888=1
119873119888119896 le 1 forall119896 (8)
119871
sum119897=1
119885119888119896119897119895 = 119910119888119896119895 forall119888 119896 119895 (9)
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119885119888119896119897119895 lowast 119879119888119901119895 lowast 119889119888119901119895119908119897
le 119867 forall119888 119896 (10)
119882119871119896 =119862
sum119888=1
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119879119888119901119895 lowast 119885119888119896119897119895 lowast 119889119888119901119895119908119897 lowast 119867
forall119896 (11)
119882119861119888 = max119896isin(12119870)
(119882119871119896 lowast 119873119888119896) forall119888 (12)
119871
sum119897=1
119885119888119896119897119895 lowast 119908119897 ge 119910119888119896119895 lowast119882119896119895 forall119888 119896 119895 (13)
119862
sum119888=1
119870
sum119896=1
119869
sum119895=1
119871
sum119897=1
(119908119897 minus119882119896119895) lowast 119879119862119895 lowast 119885119888119896119897119895 le 119881 (14)
119910119888119896119895 119873119888119896 119885119888119896119897119895 = 0 119900119903 1 forall119888 119896 119897 119895 (15)
The first part of the above objective function is tominimize total skill training cost of the needed workers Themodel set skill level varies according to standard task timeA higher skill level refers to the worker needing less time tofinish the assigned task The cost increases when the workeris trained from a lower skill level to a higher one
The second part of the objective function is to minimizethe penalty cost of workload imbalance ie to maximizeworkload balance of assigned workers in each cell Thepenalty cost forces workload balance by reasonable workerassignment and cross-training 1205871 and 1205872 display the trade-off between training expenditure and workload balance Arelatively lower value of 1205871 and a higher value of 1205872 standfor the situation that training is recommended strongly formore exact workload balance but is accompanied with moreexpenditure Conversely a relatively higher value of 1205871 and a
Mathematical Problems in Engineering 7
lower value of 1205872 stand for the situation that training is notrecommended for less expenditure but is accompanied withless exact workload balance The decision-maker could setthe value of 1205871 and 1205872 according to the recommendation oftraining for skill level enhancement
The third part focuses on minimizing the number ofassigned workers Considering the current economic envi-ronment where labor cost is rapidly increasing this researchconsiders theminimumnumber of workers as the top priorityin the model
Constraints (4) and (5) ensure that all tasks should beallocated to the workers Constraints (6) and (7) guaranteethat one worker can handle more than one task Constraint(8) ensures that one worker could not be assigned to morethan one cell Constraint (9) guarantees that worker assignedto a task with one and only skill level Constraint (10) ensuresthat the customer demand is met Constraint (11) calculatesworkload of each assigned worker Constraint (12) definesworkload of the bottleneck worker in cell Constraint (13)ensures that the skill level of the assigned worker is not lessthan its initial level Constraint (14) ensures that the totalwork training cost does not exceed budget
4 Swarm Intelligence Metaheuristics forWorker Assignment
In this section two classical PSO variants ie GPSO andLPSO and ABC are introduced briefly Next we presentthe STABC with enhanced learning strategy to improvecomputational performanceThis is followed by the designedimplementations of the algorithms for the mathematicalmodel
41 Particle Swarm Optimization Particle swarm opti-mization (PSO) is a stochastic swarm-based metaheuristicinspired by the group behaviors of bird flocking and fishingschooling [11] In PSO a group of particles are employed tocollaboratively explore the problem landscape Each particlehas velocity and position information and moves towardsits historical best position in conjunction with populationbest position found so far Supposing that searching space isD-dimensional the m-th particlersquos velocity and position areupdated as follows
119901V119889119898 = 119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119892119887119890119904119905119889119898 minus 119883119889119898)
(16)
119883119889119898 = 119883119889119898 + 119901V119889119898 (17)
where 1199031 and 1199032 are two positive constriction coefficients1199031198861198991198891198891 and 1199031198861198991198891198892 are two random numbers between [0 1]119883119898 = (1198831119898 1198832119898 119883119863119898) is the position of particle m 119901V119898 =(119901V1119898 119901V2119898 119901V119863119898) is the velocity of particle m 119901119887119890119904119905119898 =(1199011198871198901199041199051119898 1199011198871198901199041199052119898 119901119887119890119904119905119863119898) is the best previous position forparticle m and 119892119887119890119904119905119898 = (1198921198871198901199041199051119898 1198921198871198901199041199052119898 119892119887119890119904119905119863119898) is thebest position discovered by the population so far
Global topology Local topology
Figure 1 Global and local topology structure
Many variants of PSO have been studied since theinception [45 46] A standard version is presented in [32]The standard PSO employs constricted factor 120594 as shown inthe following to guide population search
120594 = 210038161003816100381610038161003816100381610038162 minus 120593 minus radic1205932 minus 4120593
1003816100381610038161003816100381610038161003816 120593 = 1199031 + 1199032 (18)
where 1199031 and 1199032 are set to be constants to ensure the speed ofconvergence [45] With the constriction factor the originalvelocity equation is given as follows
119901V119889119898 = 120594 (119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119871119864119889119898 minus 119883119889119898))
(19)
where LEd represents the previous best information in pop-ulation It is GPSO when a neighbor could be anyone withinthe population otherwise it is LPSO The structures of thetwo patterns are shown in Figure 1The general procedures ofPSO are given as follows
(1) Initialize population size of particle swarm maxi-mum number of iterations and the constants (r1 andr2)
(2) Randomly generate a swarm of particles and initializethe velocity and position of each particle in the searchboundary
(3) Evaluate each particlersquos fitness value(4) Renew particlersquos personal best by comparing current
best information with its historical best information(5) Update the swarm best information using the best
neighborsrsquo information in population(6) Each particle updates its velocity by (19)(7) Each particle updates its position by (17)(8) Go to (3) if the stop criteria are not met otherwise
terminate the iteration
42 Artificial Bee Colony Algorithm Artificial bee colony(ABC) algorithm is inspired by the foraging behaviors in ahoney bee swarm for real-parameter optimization [12] InABC there are three types of bees employed bees onlooker
8 Mathematical Problems in Engineering
bees and scout bees The goal of the whole bees is tocollaboratively find the largest source of nectar The actuallocation of the food source represents a possible solution forthe optimization problems in ABC and the density of nectarcorresponds to a fitness value of solutionThenumber of foodsources represents the swarm size PS
In the iteration each employed bee explores the foodsource using the following
119887V119889119898 = 119909119889119898 + 120601119889119898 (119909119889119898 minus 119909119889119902) 119898 = 119902 (20)
where 119887V119889119898 denotes a candidate food source positionmm= 12 PS 120601119889119898 is a randomly produced value within [-1 1] 119909119889119898refers to the corresponding food source and 119909119889119902 is a randomlyselected food source
Each onlooker bee randomly selects its food sourcem for further refinement with a probability 119901119898 which isdetermined as follows
119901119898 =119891119894119905119899119890119904119904119898
sum119878119904=1 119891119894119905119899119890119904119904119904(21)
where119891119894119905119899119890119904119904119898 is the quality of them-th food source For theminimization problem the 119891119894119905119899119890119904119904119898 can be calculated usingthe following
119891119894119905119899119890119904119904119898 =
1(1 + 119891119898)
if 119891119898 ge 01 + 119886119887119904 (119891119898) if 119891119898 le 0
(22)
where 119891119898 is the m-th objective function value The value ofldquolimitrdquo to abandon the poor food source is suggested to be setto PSlowastD [47] The main steps of ABC are given below
(1) Initialize the number of food sources the limit andthe maximum number of iterations
(2) Randomly generate the positions of food sources inproblem landscape
(3) Evaluate the fitness value of food sources foundcurrently
(4) Each employed bee explores between a randomexem-plar and their own food source using (20)
(5) Apply greedy selection process to select the best PSpositions and record the updated food sources
(6) Calculate the probability of the food sources withwhich onlooker bees are going to follow by (21)
(7) Produce new solutionusing (20) for the onlooker beesdepending on 119901119894
(8) Conduct greedy selection and update food sourceinformation for onlooker bees
(9) Abandon the food sources with poor nectar and letscouts search for new food sources
(10) Terminate if the stop criteria are met otherwise go to(4)
43 Superior Tracking Artificial Bee Colony Algorithm Asa newly proposed algorithm while promising ABC stillsuffers from two weaknesses First the convergence speed isrelatively slow compared tomany existing swarm intelligencealgorithms Second the capability of exploring global optimais still underperforming on many multimodal problems [48]In the original search behavior of ABC only one dimensionof a bee is selected to learn and renew in each round ofinformation updating This search rule may result in the slowconvergence or inferior exploring capability [49] To addressthis issue the STABC is introduced to improve the searchcapability and convergence speed for global optimization
In STABC the employed bees and onlooker bees areupdated in accordance with the following equation
119887V119898 = 119909119898 + 119903119898 (119909119898 minus 119878119873119898) (23)
where 119887V119898 represents the food position of the m-th (m=1 2 PS) food source to be updated 119903119898 refers to arandomly generated D-dimensional vector and SN is the D-dimensional constructed exemplar for tracking in which theelements are either from itself or from the other superiorfood sources randomly chosen by roulette selection andtournament selection
The detailed procedure of constructing SNm is presentedas follows
(1) Initialize a given probability Pr to decide whichexemplar the current bee should chase itself or theother superior neighbors in the population
(2) For each dimension of 119878119873119889119898 (d = 1 toD) a valuewithin[0 1] is randomly generated(3) If the generated value is larger than Pr two food
positions are randomly chosen for comparison andthe d-th dimension of the better one will be learnedotherwise 119878119873119889119898 will be itself
(4) Repeat the above steps till all dimensions of SNm aredetermined
In STABC all elements of an individual will be likely toupdate at each iteration As a result each bee either exploitsthe local optima by learning from itself or explores the globallandscape by chasing the other individuals in the populationThis search strategy accelerates the convergence speeds ofthe population In addition it remains from ABC originalproperties that every individual could be learning exemplarsFigure 2 displays the flow chart of the STABC algorithm
44 Implementation of the SI-Based Optimizers for Cell For-mation In the proposed mathematical model the computa-tional complexity is dependent on the variable size of 119885119888119896119897119895which is equal to 119888 lowast 119896 lowast 119897 lowast 119895 The search dimension ofsolutionZcklj will be too large to optimize using the traditionalmathematical methods Our preliminary experiment indi-cates that it is extremely hard to obtain a suboptimum if thevariables are without proper treatment Meanwhile a feasiblesolution Z would be hard to locate due to the complexityand discontinuity of constraints To address these issues a SI-based metaheuristic is proposed to explore the global optima
Mathematical Problems in Engineering 9
Begin
Initialize food source positions Setting criteria and itc = 1
Fitness value calculation
Evaluate new solution
Greedy SelectionCalculate the probability
of the food source
Determine the chosenfood source by the
onlooker bees
Output
N
Y
itc gt criteria
itc = itc+1
Greedy SelectionRandomly generate a new
position for the abandonedfood sources
Evaluate new solution
itc iteration counter
Trial successfully update record of each food source
Pr a threshold
randi an interger from a uniform discrete distribution
FS the position of the food sources
FV fitness value
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Figure 2 Flowchart of the STABC algorithm
While implementing the swarm-based optimizers for cross-trained worker assignment problem three important issuesshould be considered encoding decoding and constrainshandling
An effective encoding method is developed in this studyThe original 0-1 planning problem is transformed into aninteger programming problem in which the targeting skilllevel and theworker are allocated to each task tomeet the pro-duction requirements For the population initialization them-th individual is represented as 119909119898 = [1199091198981 1199091198982 119909119898119895]j = 1 2 J where J denotes the value of tasks The range ofthe algorithmic representation 1199091198981 is [1 k+l]
In the decoding process the worker and skill levelindices need to be determined through the algorithmicrepresentation A cross-reference matrix is generated here forconverting individual 119909119898 to the indices of worker and skilllevel Details of procedures involved in the decoding processfor 119909119898 are shown in Figure 3
For the constraints handling process the basic penaltyfunctionmethod is adopted [50] Once the objective functionvalue of 119909119898 and the corresponding constraint violation havebeen obtained the penalty value is added to the objectivefunction value of 119909119898
Begin
Y
1 2 hellip K1 1 2 hellip K2 hellip hellip hellip helliphellip hellip hellip hellip hellipL hellip hellip hellip K+L N
Y
Y
N
c = 1 j = 1empty Zcklj
p = 1P
Cross-reference
Inputxmj
Outputindexvalue
kl
Z(cklj) = 1j = j+1
j gt J
c = c+1j =1
c gt C
Output Zcklj
any(Tcpj)gt0
Figure 3 Decoding procedure
5 Computational Experiment
To validate effectiveness and efficiency of the proposedmathematical model and optimizers computational ex-periments are performed in this section Ten problemsare randomly generated based on previous research(can be accessed at httpsdrivegooglecomopenid=0B18FVuMxAffXLW1mRzVLczlyem8) The experiments areimplemented using MATLAB R2012a and the desktop iswith Intel Core i5 CPU 320GHz and 8GB memory
51 Experiment Settings The cross-trained worker assign-ment problem is based on the formed manufacturing cellsin this research that is part and tasks types had beenfixed after cell formation in CMS Ten cell formation prob-lems are selected from previous literature (see Table 3) Asthe problems are generated with different sizes they arenot directly correlated to each other The different typesof problem size can comprehensively evaluate the scalableperformance of the proposed method on this mathematical
10 Mathematical Problems in Engineering
Table 3 Dimension of test problems
Problem No Number ofParts Tasks Cells Workers
P1 [34] 5 5 2 5P2 [35] 7 5 2 5P3 [36] 6 6 2 6P4 [37] 8 9 2 9P5 [38] 10 8 3 8P6 [36] 8 10 3 10P7 [39] 10 10 3 10P8 [35] 12 10 3 10P9 [40] 18 10 3 10P10 [41] 22 11 3 11
Table 4 Pattern of data generation
Parameters Values119879119862119895 lowastDU(500 1000)119879119888119901119895 DU(01 15)119889119888119901119895 DU(50 150)119882119896119895 Randomly generated in set (0 07 08 09 1 11)119908119897 w1=07 w2=08 w3=09 w4=10 w5=11lowastDU(m n) means discrete uniform distribution varying between m and nThe unit of time is minute
model The additional parameters are randomly generatedas shown in Table 4 To allow one-to-one correspondencebetween workers and tasks in extreme situation we assumedthat the number of available workers is equal to the numberof tasks in CMS The available working time of each workerin a shift is calculated as 8 hlowast60mlowast85=408m The trainingbudget in the factory is sufficient Penalty cost of workloadimbalance 120572 is assumed to be 100 With respect to the trade-off between training expenditure and workload balanceldquo1205871=1 1205872=10rdquo stands for the first situation which refers tothe pursuit of more exact workload balance although moretraining cost should be spent while ldquo1205871=10 1205872=1rdquo standsfor the second situation which refers to saving training costalthough workload balance may not be enforced very well
Themaximum number of iterations is set as 20000 whereall the candidate algorithms are found to converge fast Forthe standard PSO the constant120593=41 and the values120594=07298and r1=r2=205 are gathered (Bratton and Kennedy 2007)For the STABC the range of 119903119898 is empirically set as [0149] which could be a time-varying function as well [49]With respect to the threshold probability Pr of STABC themethod introduced in Liang et alrsquos research [51] is adoptedThe population size is set at 30 for all algorithms [47]
52 Experimental Results Each problem is run indepen-dently 20 times with the four algorithms (GPSO LPSO ABCand STABC) The CPU time for each run does not exceed90s In Table 5 119874119865119881119887 119874119865119881119908 and 119874119865119881119886 represent the bestworst and average objective function values (OFV) of theten problems after 20 runs under the two situations (1205871=1
0
25000
50000
75000
100000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=1 2=10
GPSOLPSO
ABCSTABC
Figure 4 119874119865119881119887 results for the case of 1205871=1 1205872=10
1205872=10) and (1205871=10 1205872=1)The best solutions of119874119865119881119887119874119865119881119908and 119874119865119881119886 found by the four algorithms are shown in boldBased on experimental results three measures to evaluate theeffectiveness of STABC algorithm are defined as follows(1) 119861119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119887 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119861119866119866119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119887byGPSO over 119874119865119881119887 by STABC(2) 119882119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119908between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance119882119866119871119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119908 byLPSO over 119874119865119881119908 by STABC(3) 119860119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119886 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119860119866119860119861119862119878119879119860119861119862 means the rising percentage of 119874119865119881119886 byABC over 119874119865119881119886 by STABC
With respect to the abovemeasures the presented STABCis employed as the basis to compare the performance of theinvolved algorithms A positive value indicates that STABCoutperforms the other algorithms on the optimized problem
Table 6 shows the comparison results on the ten problemsunder the two situations (1205871=1 1205872=10) and (1205871=10 1205872=1) Wesee thatmost of119861119866lowast119878119879119860119861119862119882119866lowast119878119879119860119861119862119860119866lowast119878119879119860119861119862 and all averagevalues are positive Thus better results with respect to119874119865119881119887119874119865119881119908 and 119874119865119881119886 can be attained by STABC compared toGPSO LPSO and ABC under both situations (1205871=1 1205872=10)and (1205871=10 1205872=1)
Figures 4 and 5 compare the 119874119865119881119887obtained by GPSOLPSO ABC and STABC (see Table 5)They demonstrate thatthe best solutions of STABC are better than the others Forthe relatively simple small-size problems such as problems1 2 and 3 most of the algorithms can easily identify thebest results With the increase of problem size STABCoutperforms the other algorithms on the relatively large-sizeproblems The improvement of STBACrsquos search capabilitycan be attributed to two properties (1) each individualrsquoslearning speed for exploration is improved by learning fromother bees in all dimensions and (2) the individualrsquos learningsources for exploitation are enriched by learning fromboth itshistorical information and the superior individualsThenovelstrategies can significantly enhance the global exploration
Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
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2 Mathematical Problems in Engineering
to various tasks so as to optimize some output measure[8] In previous studies the cross-training problem and theworker assignment problem were always handled separatelyHowever the associated trade-offs between the two problemshave not been answered yet In this study we aim to proposea framework to solve the worker assignment problem in CMSincorporating cross-training
A major challenge arising in this context concerns theprinciple of cross-trained worker assignment in CMS whereworker-task configuration among multiple cells is exploredbased on customer demand to seek workload balance ofassigned workers with minimum cross-training and laborcost Specifically two questions should be answered(1) Which worker should be assigned to which task in
multiple manufacturing cells(2)Which worker should be trained to reach which skill
level for the assigned task in multiple manufacturing cellsPrevious studies related to the above questions mainly
have two limitations (1) They only answered the firstquestion by assuming that the skill levels of workers arefixed while neglecting the need for skill level enhancementvia cross-training Skill level enhancement denotes that theassigned worker should be trained not only for higher effi-ciency in its existing skills but also for the acquisition of newskills And (2) they mainly paid attention to flow-line systemor a single manufacturing cell and ignored the complexinteraction among multiple cells during cross-trained workerassignment in CMS
To address this gap this paper presents a novel mathe-matical programming model that aims to minimize trainingcost workload imbalance and the number of assignedworkers based on customer demand The proposed modelnot only takes into account the problem of cross-trainedworker assignment for multiple cells but also determinesthe training requirements considering the trade-off betweentraining expenditure and workload balance in the followingscenarios(1) Training is recommended strongly for more exact
workload balance which results in more expenditure(2) Training is not recommended for less expenditure
which results in less exact workload balanceIn view of the complexity and computational burden
of the presented model we implement swarm intelligenceoptimizers for the global optimization Swarm intelligence(SI) algorithms motivated by collective behaviors in naturalsystem have achieved great successful applications in var-ious areas [9 10] As a result a number of swarm-basedmetaheuristics have been developed recently among whichparticle swarm optimization (PSO) [11] and artificial beecolony (ABC) [12] are two representative algorithms PSOwas proposed for global optimization by emulating the veloc-ity adjusting of fish schooling and bird flocking ABC wasdeveloped by simulating the information exchange throughbee dancing PSO and ABC have shown high efficiencyand effectiveness in solving real-world global optimizationproblems [9] In this study the global topology PSO (GPSO)local topology PSO (LPSO) and ABC are implementedto solve the proposed cross-trained worker assignment inCMS To improve the optimization performance a superior
tracking artificial bee colony (STABC) with an augmentedinformation sharing strategy is developed In STABC thereare two main contributions compared to the canonical ABC(1) instead of learning one dimension from neighbors inSTABC a bee can learn from others in all dimensions (2)instead of chasing the random individual in STABC eachbee either learns from its previous information or movetowards other superior bees Computational experiments andcomparisons are conducted to evaluate the efficiency of theswarm intelligence algorithms
Comparing with the previous research the contributionof this study lies in three aspects(1) A new model is presented to solve the worker assign-
ment problem formultiplemanufacturing cells incorporatingcross-training planning(2)The skill enhancement is integrated to avoid excessive
training and the trade-off between training expenditureand workload balance is combined to obtain more flexiblesolution in the model(3) Swarm intelligence optimizers are developed and
improved to solve the proposed mathematical model effi-ciently
Remainder of this paper is organized as follows Section 2reviews the literaturerelating to worker assignment Section 3presentsmodel for effective cross-trainedworker assignmentSection 4 describes the swarm intelligence metaheuristicsused and the algorithmic implementation for solving theproblem Section 5 describes experiments with computa-tional results to justify the proposed model and algorithmsSection 6 summarizes the conclusions and future researchdirections
2 Literature Review
Theapproaches regarding theworker assignment problemarebriefly reviewed in this sectionThe literature can be classifiedby considering two types ofmanufacturing systems flow-linemanufacturing system (FLMS) and cellular manufacturingsystem (CMS) The limitations in previous studies are sum-marized for the motivation of our work
21 Worker Assignment in Flow-Line Manufacturing SystemHopp et al [13] considered two cross-training strategiescherry picking and skill chain In zoned work sharing somemachinestasks on the line are shared between workers toseek capacity balance Inman et al [6] argued that cross-training should be used judiciously since it is costly and islimited by learning capacity and can confound the searchfor quality problems They presented a training strategycalled chaining in which workers are trained to perform asecond task and the assignments of task types to workersare linked in a chain Their research has shown that cross-training in chaining is a practical and effective strategy tocompensate for absenteeism on assembly lines Moreira etal [14] proposed simple heuristics for solving the assemblyline worker assignment and balancing problem Their ideawas to use task and worker priority rules to define whichworker and which set of tasks should be assigned to each
Mathematical Problems in Engineering 3
workstation by constructive heuristic framework Parvin etal [15] introduced a new canonical model of worker cross-training called a Fixed Task Zone Chain A new heuris-tic worker control policy was presented to design a zonestructure that can be balanced by assigning worker to workstation based on his or her skill set for maximum throughputMutlu et al [5] solved the assembly line worker assignmentand balancing problem when task times differ depending onoperator skills and concerns with the assignment of tasks andoperators to stations in order to minimize the cycle timeSaidi-Mehrabad et al [16] presented a novel integer linearprogramming model for dynamic manufacturing systems inthe presence of system configurations worker assignmentand production plan for each part type at each period Theobjective of worker assignment is to minimize training andsalary of worker costs Sungur and Yavuz [17] consideredqualification requirements and levels of workers to achieveassembly line balance and worker assignment problem Theysuggested that the workers should be ranked hierarchicallyaccording to their qualification requirements and levelsFrom the standpoint of the paper a higher qualified workerimplies a higher cost and lower process time
22 Worker Assignment in Cellular Manufacturing SystemThe proposed strategies of worker assignment in CMS canbe divided into two categories (1) simultaneous formation ofmanufacturing cells and worker assignment and (2) assign-ment of workers to cells after cell formation
221 Simultaneous Formation of Manufacturing Cells andWorker Assignment The strategy of forming manufacturingcells and worker assignment simultaneously was achievedfirst by Aryanezhad et al [18] The first part of the modelobjective function proposed in their study sought to mini-mize production cost intercell material handling cost andmachine costs in the planning horizon The second partinvolved human issues including hiring cost firing costtraining cost and salary into worker assignment in cellsHowever this study ignored efficiency of workersrsquo skills indifferent tasks Mahdavi et al [19] determined optimal cellconfigurations worker assignments and process plans usingan integer mathematical programming model The purposewas to minimize holding and backorder intercell materialhandling machine and reconfiguration and workers hiringfiring and salary costs Their model was solved by branch-and-bound (BampB)method using Lingo 80 softwareMahdaviet al [20] presented a fuzzy goal programming for groupingmachines parts and workers simultaneously and determin-ing production planning in dynamic virtual CMS Theirmodel aimed to minimize inventory holding and backordercosts as well as the number of exceptional elements in a cubicspace of machine-part-worker incidence matrix under con-straints of machine capacity worker capacity and customerdemand Bagheri and Bashiri [21] proposed a mathematicalmodel to simultaneously solve the cell formation operatorassignment and intercell layout problems Salary hiringfiring and training cost were considered while optimizing
worker assignment Their results indicated that consider-ation of the operator assignment problem has significantimpact on the overall system efficiency Niakan et al [22]proposed a new biobjective mathematical model to solvedynamic cell formation and skill-based worker assignmentproblem Environmental and social criteria were consideredin their research Due to the NP-hardness of the problemthey merged an efficient hybrid metaheuristic based on thenondominated sorting genetic algorithm with multiobjectivesimulated annealing Liu et al [1] built an integrated modelto solve the problems of machine grouping part schedulingworker assignment for minimizing material handling costsand the fixed and operating costs of machines and workersThey also developed a discrete bacteria foraging algorithmcombining with priority rule based parallel schedule gener-ation scheme for the intractable model Liu et al [23] builtanother integrated model to solve worker assignment andproduction planning problem again for CMS In the newmodel they assumed that all workers had the characteristicsof learning or forgetting
222 Assignment of Workers to Cells after Cell FormationMore previous studies focused on the problem of assigningworkers to tasks in cells after cell formation Askin andHuang[24] presented a mixed integer goal programming modelfor solving the worker assignment problem and coming upwith a training plan for technical and administrative skillsThemodel aimed to maximize team synergy between workerabilities and task requirements while minimizing trainingcost Greedy heuristic filtered beam search and simulatedannealing techniques were developed and tested to solve theproblem Norman et al [25] considered productivity outputquality and training costs in assigning workers to manufac-turing cells with the objective of maximizing the effectivenessof the organization Comparing with traditional workerassignments the model in their research did not include notonly technical skills but also human skills Ertay and Ruan[26] noted a data envelopment analysis to determine themost efficient number of operators and efficientmeasurementof labor assignment in CMS Fitzpatrick and Askin [27])developedmathematical models for forming effective humanteams by selecting suitable interpersonal construction andconsidering technical skill requirements from initial laborpools Meanwhile extensive cross-training policies were alsoattained to optimize team performance and a balancedplacement heuristic was proposed and evaluated Cesani andSteudel [28] simultaneously considered concepts of workloadsharing workload balancing and the presence of bottleneckoperations to classify labor strategies according to type ofmachine-operator assignments including dedicated sharedand combined assignment Simulation modeling was usedto test suitability of these concepts in an actual cell imple-mentation Suer and Tummaluri [7] developed mathematicalmodels to tackle three problems finding alternative cellconfigurations loading cells and finding crew sizes andassigning operators to operations They also proposed twoheuristic approaches for operator assignment McDonald etal [29] presented a mathematical model to solve the worker
4 Mathematical Problems in Engineering
assignment arising in a lean manufacturing cell The modelsought minimum cost of training inventory and poor qualityto determine skill training necessary for workers to meettasks and customer demand Their study also proposed theaddition of pay-for-skills reward in evaluating the costs andbenefits of cross-training However their study had onlyfocused on worker assignment for a single cell althoughmultiple cells exist in the CMS Murali et al [30] developedan artificial neural network model for assigning workforce invirtual cells under dual resource constrained context wherethe number of available workers is less than total numberof available machines Egilmez et al [31] developed a four-phased hierarchical methodology to address the stochasticskill-based manpower allocation problem In their studyworkerrsquos expected processing time and the standard deviationfor each operation were considered individually to optimizethe worker assignment to cells and maximize the productionrate of manufacturing system Table 1 presents a classificationof the previous studies
The aforementioned studies had pointed out that workerassignment plays an essential role in both flow-line andcellular manufacturing system To explore the problemof workload balance among assigned workers the cross-training strategy has been examined widely However mostof previous studies just determined which worker shouldbe trained for which task The question of an effectivestrategy of need for cross-training by prioritizing exact skilllevel of worker to avoid excessive training was ignoredThat is very few achievements specifically indicated howmany workers and in which skills they should be trained towhich level with minimum training and labor cost as wellas maximum workload balance Moreover the question oftrade-off between training expenditure andworkload balancecould lead to more flexible worker assignment and cross-training policies which did not attract significant interestin previous study Besides for the question of balancingworkload of assigned workers during cross-trained workerassignment most of previous studies paid attention to flow-line manufacturing system or a single manufacturing cellThe solution of this question formultiple manufacturing cellsshould receive more concern because it is more complex andpractical due to the interplay among cells
Considering the high complexity of the NP-hard prob-lem optimization software (LINGO CPLEX) were accompa-nied with long runtime consumption Consequently efficientmetaheuristics for the models have been attracting growingattention in recent years especially swarm intelligence meta-heuristics For example ABC was employed to address theuncovering community problem in complex networks [42]and a novel PSO algorithm was utilized for power systemoptimization [43] However few researchers used the swarmintelligence metaheuristics to solve the problem of cross-trained worker assignment for multiple cells
To fill the gaps in the literature this study aimsto build a new model to address the worker assign-ment problem among multiple manufacturing cells whileincorporating cross-training planning for workload balanceand develop solutions based on the swarm intelligencealgorithms
3 Proposed Model for Cross-TrainedWorker Assignment
This section elaborates the mathematical model for theproblem of cross-trained worker assignment in CMS Weassume that part families have already been formed andthe machines have been allocated to each part family Thetype of manufacturing cell is considered a divisional cellwhere tasks are divided among several workers in accordancewith their skill levels and task time Workers cooperate andshuttle among the workstations to complete one or severaldiscrete or successive tasks [44] Based on the feature ofcellular manufacturing system several part types with similaroperations form a part family which are processed by a groupof machines and workers in each manufacturing cell Thatmeans tasks for processing different part types in a cell aresimilar In this paper we consider skill as workerrsquos capabilityon assigned task including machine and hand operationsSome other operational assumptions and statements arestated as follows
(i) The initial skill level of each worker is given(ii)The processing time for each task for each part type is
known(iii) Each worker is assigned just to one cell(iv) Each task is assigned just to one worker(v) Machine breakdown and absenteeism are not consid-
ered(vi) All materials are delivered on time(vii) Training time is not considered(viii) The training cost of each worker for each task
depends on the task type and the skill level but not on the parttypes For instance part types 1 and 2 include task 1 which ishandled by worker 1 in a cell Training cost of worker 1 justdepends on task 1 but not on the part type
(ix) Each worker can handle all part types that arrive athis or her task stations
31 Model Notations Table 2 summarizes the index setsparameters and variables used in the proposed model
32 Mathematical Formulation The cross-trained workerassignment problem for multiple cells in CMS can be for-mulated as a nonlinear 0ndash1 integer programming model asfollows
119872119894119899 = 1205871 lowast119862
sum119888=1
119870
sum119896=1
119869
sum119895=1
119871
sum119897=1
(119908119897 minus119882119896119895) lowast 119879119862119895 lowast 119885119888119896119897119895 (1)
+1205872 lowast 120572 lowast119862
sum119888=1
119882119861119888 lowast sum119870119896=1119873119888119896sum119870119896=1119882119871119896 lowast 119873119888119896
(2)
+119862
sum119888=1
119870
sum119896=1
119873119888119896 lowast119872 (3)
subject to119870
sum119896=1
119910119888119896119895 = 1 for forall119888 119895 satisfying119875
sum119901=1
119879119888119901119895 gt 0 (4)
Mathematical Problems in Engineering 5
Table1Th
eclassificatio
nof
relatedliterature
Author
Manufacturin
gsystem
type
Num
bero
fcells
Skill
level
Cross-T
raining
Workloadbalance
Datan
ature
Solvingmetho
dHop
petal[13]
FLMS
radicradic
Stochastic
Heuris
ticPo
licies
Inman
etal[6]
FLMS
radicStochastic
Simulation
Moreira
etal[14]
FLMS
radicCertain
HGA
Mutluetal[5]
FLMS
radicCertain
IGA
Saidi-M
ehrabadetal[16]
FLMS
radicradic
Stochastic
LINGO
Sung
urandYavu
zetal[17]
FLMS
radicCertain
CPLE
XParvin
etal[15]
FLMS
radicradic
Stochastic
Heuris
ticPo
licies
Aryanezhadetal[18]
CMS
Multip
leradic
radicCertain
LINGO
Mahdavietal[19]
CMS
Multip
leCertain
LINGO
Mahdavietal[20]
CMS
Multip
leCertain
LINGO
Bagh
eriand
Bashiri
[32]
CMS
Multip
leradic
Stochastic
LINGO
Niakanetal[22]
CMS
Multip
leradic
radicStochastic
NSG
AII-
MOSA
Liuetal[1]
CMS
Multip
leStochastic
DBF
ALiuetal[23]
CMS
Multip
leradic
Certain
HBF
AAskin
andHuang
[24]
CMS
Multip
leradic
radicStochastic
Greedyheuristic
Norman
etal[25]
CMS
Sing
leradic
radicStochastic
CPLE
XErtayandRu
an[26]
CMS
Sing
leStochastic
DEA
FitzpatrickandAskin
[27]
CMS
Sing
leradic
Stochastic
Balanced
placem
enth
euris
ticCesaniand
Steudel[28]
CMS
Sing
leradic
Certain
Simulation
Suer
andTu
mmaluri[33]
CMS
Sing
leradic
Stochastic
Max
andMaxMin
heuristic
McD
onaldetal[29]
CMS
Sing
leradic
radicCertain
CPLE
XMuralietal[30]
CMS
Multip
leradic
radicCertain
ANN
Egilm
ezetal[31]
CMS
Multip
leradic
Certain
LINGO
6 Mathematical Problems in Engineering
Table 2 Model notations and definitions
Index sets Definitions119888 Index of cells (119888 = 1 2 119862)119901 Index of parts (119901 = 1 2 119875)119895 Index of tasks (119895 = 1 2 119869)119896 Index of workers (119896 = 1 2 119870)119897 Index of skill levels (119897 = 1 2 119871)Parameters Definitions119862 Number of cells119875 Number of parts119869 Number of tasks119870 Number of workers119871 Number of skill levels119879119862119895 Training cost of task 119895119879119888119901119895 Standard processing time of part type 119901 at task 119895 in cell 119888119889119888119901119895 Required throughput of part type 119901 at task 119895 in cell 119888 in one shift119882119896119895 Initial skill level weight of worker k at task 119895119908119897 Weight of skill level 119897119867 Available working time in one shift119881 Maximum permissible training cost120572 Penalty cost of workload imbalance119872 Large value1205871 1205872 Weight factorsVariables Definitions119885119888119896119897119895 1 if worker k with skill level l will be assigned to task j in cell c 0 otherwise119910119888119896119895 1 if worker k will be assigned to task j in cell c 0 otherwise119873119888119896 1 if worker k will be assigned into cell c 0 otherwise119882119871119896 Workload of worker k119882119861119888 Workload of bottleneck worker in cell c
119870
sum119896=1
119910119888119896119895 = 0 for forall119888 119895 satisfying119875
sum119901=1
119879119888119901119895 = 0 (5)
119873119888119896 = 1 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 ge 1 (6)
119873119888119896 = 0 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 = 0 (7)
119862
sum119888=1
119873119888119896 le 1 forall119896 (8)
119871
sum119897=1
119885119888119896119897119895 = 119910119888119896119895 forall119888 119896 119895 (9)
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119885119888119896119897119895 lowast 119879119888119901119895 lowast 119889119888119901119895119908119897
le 119867 forall119888 119896 (10)
119882119871119896 =119862
sum119888=1
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119879119888119901119895 lowast 119885119888119896119897119895 lowast 119889119888119901119895119908119897 lowast 119867
forall119896 (11)
119882119861119888 = max119896isin(12119870)
(119882119871119896 lowast 119873119888119896) forall119888 (12)
119871
sum119897=1
119885119888119896119897119895 lowast 119908119897 ge 119910119888119896119895 lowast119882119896119895 forall119888 119896 119895 (13)
119862
sum119888=1
119870
sum119896=1
119869
sum119895=1
119871
sum119897=1
(119908119897 minus119882119896119895) lowast 119879119862119895 lowast 119885119888119896119897119895 le 119881 (14)
119910119888119896119895 119873119888119896 119885119888119896119897119895 = 0 119900119903 1 forall119888 119896 119897 119895 (15)
The first part of the above objective function is tominimize total skill training cost of the needed workers Themodel set skill level varies according to standard task timeA higher skill level refers to the worker needing less time tofinish the assigned task The cost increases when the workeris trained from a lower skill level to a higher one
The second part of the objective function is to minimizethe penalty cost of workload imbalance ie to maximizeworkload balance of assigned workers in each cell Thepenalty cost forces workload balance by reasonable workerassignment and cross-training 1205871 and 1205872 display the trade-off between training expenditure and workload balance Arelatively lower value of 1205871 and a higher value of 1205872 standfor the situation that training is recommended strongly formore exact workload balance but is accompanied with moreexpenditure Conversely a relatively higher value of 1205871 and a
Mathematical Problems in Engineering 7
lower value of 1205872 stand for the situation that training is notrecommended for less expenditure but is accompanied withless exact workload balance The decision-maker could setthe value of 1205871 and 1205872 according to the recommendation oftraining for skill level enhancement
The third part focuses on minimizing the number ofassigned workers Considering the current economic envi-ronment where labor cost is rapidly increasing this researchconsiders theminimumnumber of workers as the top priorityin the model
Constraints (4) and (5) ensure that all tasks should beallocated to the workers Constraints (6) and (7) guaranteethat one worker can handle more than one task Constraint(8) ensures that one worker could not be assigned to morethan one cell Constraint (9) guarantees that worker assignedto a task with one and only skill level Constraint (10) ensuresthat the customer demand is met Constraint (11) calculatesworkload of each assigned worker Constraint (12) definesworkload of the bottleneck worker in cell Constraint (13)ensures that the skill level of the assigned worker is not lessthan its initial level Constraint (14) ensures that the totalwork training cost does not exceed budget
4 Swarm Intelligence Metaheuristics forWorker Assignment
In this section two classical PSO variants ie GPSO andLPSO and ABC are introduced briefly Next we presentthe STABC with enhanced learning strategy to improvecomputational performanceThis is followed by the designedimplementations of the algorithms for the mathematicalmodel
41 Particle Swarm Optimization Particle swarm opti-mization (PSO) is a stochastic swarm-based metaheuristicinspired by the group behaviors of bird flocking and fishingschooling [11] In PSO a group of particles are employed tocollaboratively explore the problem landscape Each particlehas velocity and position information and moves towardsits historical best position in conjunction with populationbest position found so far Supposing that searching space isD-dimensional the m-th particlersquos velocity and position areupdated as follows
119901V119889119898 = 119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119892119887119890119904119905119889119898 minus 119883119889119898)
(16)
119883119889119898 = 119883119889119898 + 119901V119889119898 (17)
where 1199031 and 1199032 are two positive constriction coefficients1199031198861198991198891198891 and 1199031198861198991198891198892 are two random numbers between [0 1]119883119898 = (1198831119898 1198832119898 119883119863119898) is the position of particle m 119901V119898 =(119901V1119898 119901V2119898 119901V119863119898) is the velocity of particle m 119901119887119890119904119905119898 =(1199011198871198901199041199051119898 1199011198871198901199041199052119898 119901119887119890119904119905119863119898) is the best previous position forparticle m and 119892119887119890119904119905119898 = (1198921198871198901199041199051119898 1198921198871198901199041199052119898 119892119887119890119904119905119863119898) is thebest position discovered by the population so far
Global topology Local topology
Figure 1 Global and local topology structure
Many variants of PSO have been studied since theinception [45 46] A standard version is presented in [32]The standard PSO employs constricted factor 120594 as shown inthe following to guide population search
120594 = 210038161003816100381610038161003816100381610038162 minus 120593 minus radic1205932 minus 4120593
1003816100381610038161003816100381610038161003816 120593 = 1199031 + 1199032 (18)
where 1199031 and 1199032 are set to be constants to ensure the speed ofconvergence [45] With the constriction factor the originalvelocity equation is given as follows
119901V119889119898 = 120594 (119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119871119864119889119898 minus 119883119889119898))
(19)
where LEd represents the previous best information in pop-ulation It is GPSO when a neighbor could be anyone withinthe population otherwise it is LPSO The structures of thetwo patterns are shown in Figure 1The general procedures ofPSO are given as follows
(1) Initialize population size of particle swarm maxi-mum number of iterations and the constants (r1 andr2)
(2) Randomly generate a swarm of particles and initializethe velocity and position of each particle in the searchboundary
(3) Evaluate each particlersquos fitness value(4) Renew particlersquos personal best by comparing current
best information with its historical best information(5) Update the swarm best information using the best
neighborsrsquo information in population(6) Each particle updates its velocity by (19)(7) Each particle updates its position by (17)(8) Go to (3) if the stop criteria are not met otherwise
terminate the iteration
42 Artificial Bee Colony Algorithm Artificial bee colony(ABC) algorithm is inspired by the foraging behaviors in ahoney bee swarm for real-parameter optimization [12] InABC there are three types of bees employed bees onlooker
8 Mathematical Problems in Engineering
bees and scout bees The goal of the whole bees is tocollaboratively find the largest source of nectar The actuallocation of the food source represents a possible solution forthe optimization problems in ABC and the density of nectarcorresponds to a fitness value of solutionThenumber of foodsources represents the swarm size PS
In the iteration each employed bee explores the foodsource using the following
119887V119889119898 = 119909119889119898 + 120601119889119898 (119909119889119898 minus 119909119889119902) 119898 = 119902 (20)
where 119887V119889119898 denotes a candidate food source positionmm= 12 PS 120601119889119898 is a randomly produced value within [-1 1] 119909119889119898refers to the corresponding food source and 119909119889119902 is a randomlyselected food source
Each onlooker bee randomly selects its food sourcem for further refinement with a probability 119901119898 which isdetermined as follows
119901119898 =119891119894119905119899119890119904119904119898
sum119878119904=1 119891119894119905119899119890119904119904119904(21)
where119891119894119905119899119890119904119904119898 is the quality of them-th food source For theminimization problem the 119891119894119905119899119890119904119904119898 can be calculated usingthe following
119891119894119905119899119890119904119904119898 =
1(1 + 119891119898)
if 119891119898 ge 01 + 119886119887119904 (119891119898) if 119891119898 le 0
(22)
where 119891119898 is the m-th objective function value The value ofldquolimitrdquo to abandon the poor food source is suggested to be setto PSlowastD [47] The main steps of ABC are given below
(1) Initialize the number of food sources the limit andthe maximum number of iterations
(2) Randomly generate the positions of food sources inproblem landscape
(3) Evaluate the fitness value of food sources foundcurrently
(4) Each employed bee explores between a randomexem-plar and their own food source using (20)
(5) Apply greedy selection process to select the best PSpositions and record the updated food sources
(6) Calculate the probability of the food sources withwhich onlooker bees are going to follow by (21)
(7) Produce new solutionusing (20) for the onlooker beesdepending on 119901119894
(8) Conduct greedy selection and update food sourceinformation for onlooker bees
(9) Abandon the food sources with poor nectar and letscouts search for new food sources
(10) Terminate if the stop criteria are met otherwise go to(4)
43 Superior Tracking Artificial Bee Colony Algorithm Asa newly proposed algorithm while promising ABC stillsuffers from two weaknesses First the convergence speed isrelatively slow compared tomany existing swarm intelligencealgorithms Second the capability of exploring global optimais still underperforming on many multimodal problems [48]In the original search behavior of ABC only one dimensionof a bee is selected to learn and renew in each round ofinformation updating This search rule may result in the slowconvergence or inferior exploring capability [49] To addressthis issue the STABC is introduced to improve the searchcapability and convergence speed for global optimization
In STABC the employed bees and onlooker bees areupdated in accordance with the following equation
119887V119898 = 119909119898 + 119903119898 (119909119898 minus 119878119873119898) (23)
where 119887V119898 represents the food position of the m-th (m=1 2 PS) food source to be updated 119903119898 refers to arandomly generated D-dimensional vector and SN is the D-dimensional constructed exemplar for tracking in which theelements are either from itself or from the other superiorfood sources randomly chosen by roulette selection andtournament selection
The detailed procedure of constructing SNm is presentedas follows
(1) Initialize a given probability Pr to decide whichexemplar the current bee should chase itself or theother superior neighbors in the population
(2) For each dimension of 119878119873119889119898 (d = 1 toD) a valuewithin[0 1] is randomly generated(3) If the generated value is larger than Pr two food
positions are randomly chosen for comparison andthe d-th dimension of the better one will be learnedotherwise 119878119873119889119898 will be itself
(4) Repeat the above steps till all dimensions of SNm aredetermined
In STABC all elements of an individual will be likely toupdate at each iteration As a result each bee either exploitsthe local optima by learning from itself or explores the globallandscape by chasing the other individuals in the populationThis search strategy accelerates the convergence speeds ofthe population In addition it remains from ABC originalproperties that every individual could be learning exemplarsFigure 2 displays the flow chart of the STABC algorithm
44 Implementation of the SI-Based Optimizers for Cell For-mation In the proposed mathematical model the computa-tional complexity is dependent on the variable size of 119885119888119896119897119895which is equal to 119888 lowast 119896 lowast 119897 lowast 119895 The search dimension ofsolutionZcklj will be too large to optimize using the traditionalmathematical methods Our preliminary experiment indi-cates that it is extremely hard to obtain a suboptimum if thevariables are without proper treatment Meanwhile a feasiblesolution Z would be hard to locate due to the complexityand discontinuity of constraints To address these issues a SI-based metaheuristic is proposed to explore the global optima
Mathematical Problems in Engineering 9
Begin
Initialize food source positions Setting criteria and itc = 1
Fitness value calculation
Evaluate new solution
Greedy SelectionCalculate the probability
of the food source
Determine the chosenfood source by the
onlooker bees
Output
N
Y
itc gt criteria
itc = itc+1
Greedy SelectionRandomly generate a new
position for the abandonedfood sources
Evaluate new solution
itc iteration counter
Trial successfully update record of each food source
Pr a threshold
randi an interger from a uniform discrete distribution
FS the position of the food sources
FV fitness value
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Figure 2 Flowchart of the STABC algorithm
While implementing the swarm-based optimizers for cross-trained worker assignment problem three important issuesshould be considered encoding decoding and constrainshandling
An effective encoding method is developed in this studyThe original 0-1 planning problem is transformed into aninteger programming problem in which the targeting skilllevel and theworker are allocated to each task tomeet the pro-duction requirements For the population initialization them-th individual is represented as 119909119898 = [1199091198981 1199091198982 119909119898119895]j = 1 2 J where J denotes the value of tasks The range ofthe algorithmic representation 1199091198981 is [1 k+l]
In the decoding process the worker and skill levelindices need to be determined through the algorithmicrepresentation A cross-reference matrix is generated here forconverting individual 119909119898 to the indices of worker and skilllevel Details of procedures involved in the decoding processfor 119909119898 are shown in Figure 3
For the constraints handling process the basic penaltyfunctionmethod is adopted [50] Once the objective functionvalue of 119909119898 and the corresponding constraint violation havebeen obtained the penalty value is added to the objectivefunction value of 119909119898
Begin
Y
1 2 hellip K1 1 2 hellip K2 hellip hellip hellip helliphellip hellip hellip hellip hellipL hellip hellip hellip K+L N
Y
Y
N
c = 1 j = 1empty Zcklj
p = 1P
Cross-reference
Inputxmj
Outputindexvalue
kl
Z(cklj) = 1j = j+1
j gt J
c = c+1j =1
c gt C
Output Zcklj
any(Tcpj)gt0
Figure 3 Decoding procedure
5 Computational Experiment
To validate effectiveness and efficiency of the proposedmathematical model and optimizers computational ex-periments are performed in this section Ten problemsare randomly generated based on previous research(can be accessed at httpsdrivegooglecomopenid=0B18FVuMxAffXLW1mRzVLczlyem8) The experiments areimplemented using MATLAB R2012a and the desktop iswith Intel Core i5 CPU 320GHz and 8GB memory
51 Experiment Settings The cross-trained worker assign-ment problem is based on the formed manufacturing cellsin this research that is part and tasks types had beenfixed after cell formation in CMS Ten cell formation prob-lems are selected from previous literature (see Table 3) Asthe problems are generated with different sizes they arenot directly correlated to each other The different typesof problem size can comprehensively evaluate the scalableperformance of the proposed method on this mathematical
10 Mathematical Problems in Engineering
Table 3 Dimension of test problems
Problem No Number ofParts Tasks Cells Workers
P1 [34] 5 5 2 5P2 [35] 7 5 2 5P3 [36] 6 6 2 6P4 [37] 8 9 2 9P5 [38] 10 8 3 8P6 [36] 8 10 3 10P7 [39] 10 10 3 10P8 [35] 12 10 3 10P9 [40] 18 10 3 10P10 [41] 22 11 3 11
Table 4 Pattern of data generation
Parameters Values119879119862119895 lowastDU(500 1000)119879119888119901119895 DU(01 15)119889119888119901119895 DU(50 150)119882119896119895 Randomly generated in set (0 07 08 09 1 11)119908119897 w1=07 w2=08 w3=09 w4=10 w5=11lowastDU(m n) means discrete uniform distribution varying between m and nThe unit of time is minute
model The additional parameters are randomly generatedas shown in Table 4 To allow one-to-one correspondencebetween workers and tasks in extreme situation we assumedthat the number of available workers is equal to the numberof tasks in CMS The available working time of each workerin a shift is calculated as 8 hlowast60mlowast85=408m The trainingbudget in the factory is sufficient Penalty cost of workloadimbalance 120572 is assumed to be 100 With respect to the trade-off between training expenditure and workload balanceldquo1205871=1 1205872=10rdquo stands for the first situation which refers tothe pursuit of more exact workload balance although moretraining cost should be spent while ldquo1205871=10 1205872=1rdquo standsfor the second situation which refers to saving training costalthough workload balance may not be enforced very well
Themaximum number of iterations is set as 20000 whereall the candidate algorithms are found to converge fast Forthe standard PSO the constant120593=41 and the values120594=07298and r1=r2=205 are gathered (Bratton and Kennedy 2007)For the STABC the range of 119903119898 is empirically set as [0149] which could be a time-varying function as well [49]With respect to the threshold probability Pr of STABC themethod introduced in Liang et alrsquos research [51] is adoptedThe population size is set at 30 for all algorithms [47]
52 Experimental Results Each problem is run indepen-dently 20 times with the four algorithms (GPSO LPSO ABCand STABC) The CPU time for each run does not exceed90s In Table 5 119874119865119881119887 119874119865119881119908 and 119874119865119881119886 represent the bestworst and average objective function values (OFV) of theten problems after 20 runs under the two situations (1205871=1
0
25000
50000
75000
100000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=1 2=10
GPSOLPSO
ABCSTABC
Figure 4 119874119865119881119887 results for the case of 1205871=1 1205872=10
1205872=10) and (1205871=10 1205872=1)The best solutions of119874119865119881119887119874119865119881119908and 119874119865119881119886 found by the four algorithms are shown in boldBased on experimental results three measures to evaluate theeffectiveness of STABC algorithm are defined as follows(1) 119861119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119887 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119861119866119866119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119887byGPSO over 119874119865119881119887 by STABC(2) 119882119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119908between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance119882119866119871119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119908 byLPSO over 119874119865119881119908 by STABC(3) 119860119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119886 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119860119866119860119861119862119878119879119860119861119862 means the rising percentage of 119874119865119881119886 byABC over 119874119865119881119886 by STABC
With respect to the abovemeasures the presented STABCis employed as the basis to compare the performance of theinvolved algorithms A positive value indicates that STABCoutperforms the other algorithms on the optimized problem
Table 6 shows the comparison results on the ten problemsunder the two situations (1205871=1 1205872=10) and (1205871=10 1205872=1) Wesee thatmost of119861119866lowast119878119879119860119861119862119882119866lowast119878119879119860119861119862119860119866lowast119878119879119860119861119862 and all averagevalues are positive Thus better results with respect to119874119865119881119887119874119865119881119908 and 119874119865119881119886 can be attained by STABC compared toGPSO LPSO and ABC under both situations (1205871=1 1205872=10)and (1205871=10 1205872=1)
Figures 4 and 5 compare the 119874119865119881119887obtained by GPSOLPSO ABC and STABC (see Table 5)They demonstrate thatthe best solutions of STABC are better than the others Forthe relatively simple small-size problems such as problems1 2 and 3 most of the algorithms can easily identify thebest results With the increase of problem size STABCoutperforms the other algorithms on the relatively large-sizeproblems The improvement of STBACrsquos search capabilitycan be attributed to two properties (1) each individualrsquoslearning speed for exploration is improved by learning fromother bees in all dimensions and (2) the individualrsquos learningsources for exploitation are enriched by learning fromboth itshistorical information and the superior individualsThenovelstrategies can significantly enhance the global exploration
Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
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Mathematical Problems in Engineering 3
workstation by constructive heuristic framework Parvin etal [15] introduced a new canonical model of worker cross-training called a Fixed Task Zone Chain A new heuris-tic worker control policy was presented to design a zonestructure that can be balanced by assigning worker to workstation based on his or her skill set for maximum throughputMutlu et al [5] solved the assembly line worker assignmentand balancing problem when task times differ depending onoperator skills and concerns with the assignment of tasks andoperators to stations in order to minimize the cycle timeSaidi-Mehrabad et al [16] presented a novel integer linearprogramming model for dynamic manufacturing systems inthe presence of system configurations worker assignmentand production plan for each part type at each period Theobjective of worker assignment is to minimize training andsalary of worker costs Sungur and Yavuz [17] consideredqualification requirements and levels of workers to achieveassembly line balance and worker assignment problem Theysuggested that the workers should be ranked hierarchicallyaccording to their qualification requirements and levelsFrom the standpoint of the paper a higher qualified workerimplies a higher cost and lower process time
22 Worker Assignment in Cellular Manufacturing SystemThe proposed strategies of worker assignment in CMS canbe divided into two categories (1) simultaneous formation ofmanufacturing cells and worker assignment and (2) assign-ment of workers to cells after cell formation
221 Simultaneous Formation of Manufacturing Cells andWorker Assignment The strategy of forming manufacturingcells and worker assignment simultaneously was achievedfirst by Aryanezhad et al [18] The first part of the modelobjective function proposed in their study sought to mini-mize production cost intercell material handling cost andmachine costs in the planning horizon The second partinvolved human issues including hiring cost firing costtraining cost and salary into worker assignment in cellsHowever this study ignored efficiency of workersrsquo skills indifferent tasks Mahdavi et al [19] determined optimal cellconfigurations worker assignments and process plans usingan integer mathematical programming model The purposewas to minimize holding and backorder intercell materialhandling machine and reconfiguration and workers hiringfiring and salary costs Their model was solved by branch-and-bound (BampB)method using Lingo 80 softwareMahdaviet al [20] presented a fuzzy goal programming for groupingmachines parts and workers simultaneously and determin-ing production planning in dynamic virtual CMS Theirmodel aimed to minimize inventory holding and backordercosts as well as the number of exceptional elements in a cubicspace of machine-part-worker incidence matrix under con-straints of machine capacity worker capacity and customerdemand Bagheri and Bashiri [21] proposed a mathematicalmodel to simultaneously solve the cell formation operatorassignment and intercell layout problems Salary hiringfiring and training cost were considered while optimizing
worker assignment Their results indicated that consider-ation of the operator assignment problem has significantimpact on the overall system efficiency Niakan et al [22]proposed a new biobjective mathematical model to solvedynamic cell formation and skill-based worker assignmentproblem Environmental and social criteria were consideredin their research Due to the NP-hardness of the problemthey merged an efficient hybrid metaheuristic based on thenondominated sorting genetic algorithm with multiobjectivesimulated annealing Liu et al [1] built an integrated modelto solve the problems of machine grouping part schedulingworker assignment for minimizing material handling costsand the fixed and operating costs of machines and workersThey also developed a discrete bacteria foraging algorithmcombining with priority rule based parallel schedule gener-ation scheme for the intractable model Liu et al [23] builtanother integrated model to solve worker assignment andproduction planning problem again for CMS In the newmodel they assumed that all workers had the characteristicsof learning or forgetting
222 Assignment of Workers to Cells after Cell FormationMore previous studies focused on the problem of assigningworkers to tasks in cells after cell formation Askin andHuang[24] presented a mixed integer goal programming modelfor solving the worker assignment problem and coming upwith a training plan for technical and administrative skillsThemodel aimed to maximize team synergy between workerabilities and task requirements while minimizing trainingcost Greedy heuristic filtered beam search and simulatedannealing techniques were developed and tested to solve theproblem Norman et al [25] considered productivity outputquality and training costs in assigning workers to manufac-turing cells with the objective of maximizing the effectivenessof the organization Comparing with traditional workerassignments the model in their research did not include notonly technical skills but also human skills Ertay and Ruan[26] noted a data envelopment analysis to determine themost efficient number of operators and efficientmeasurementof labor assignment in CMS Fitzpatrick and Askin [27])developedmathematical models for forming effective humanteams by selecting suitable interpersonal construction andconsidering technical skill requirements from initial laborpools Meanwhile extensive cross-training policies were alsoattained to optimize team performance and a balancedplacement heuristic was proposed and evaluated Cesani andSteudel [28] simultaneously considered concepts of workloadsharing workload balancing and the presence of bottleneckoperations to classify labor strategies according to type ofmachine-operator assignments including dedicated sharedand combined assignment Simulation modeling was usedto test suitability of these concepts in an actual cell imple-mentation Suer and Tummaluri [7] developed mathematicalmodels to tackle three problems finding alternative cellconfigurations loading cells and finding crew sizes andassigning operators to operations They also proposed twoheuristic approaches for operator assignment McDonald etal [29] presented a mathematical model to solve the worker
4 Mathematical Problems in Engineering
assignment arising in a lean manufacturing cell The modelsought minimum cost of training inventory and poor qualityto determine skill training necessary for workers to meettasks and customer demand Their study also proposed theaddition of pay-for-skills reward in evaluating the costs andbenefits of cross-training However their study had onlyfocused on worker assignment for a single cell althoughmultiple cells exist in the CMS Murali et al [30] developedan artificial neural network model for assigning workforce invirtual cells under dual resource constrained context wherethe number of available workers is less than total numberof available machines Egilmez et al [31] developed a four-phased hierarchical methodology to address the stochasticskill-based manpower allocation problem In their studyworkerrsquos expected processing time and the standard deviationfor each operation were considered individually to optimizethe worker assignment to cells and maximize the productionrate of manufacturing system Table 1 presents a classificationof the previous studies
The aforementioned studies had pointed out that workerassignment plays an essential role in both flow-line andcellular manufacturing system To explore the problemof workload balance among assigned workers the cross-training strategy has been examined widely However mostof previous studies just determined which worker shouldbe trained for which task The question of an effectivestrategy of need for cross-training by prioritizing exact skilllevel of worker to avoid excessive training was ignoredThat is very few achievements specifically indicated howmany workers and in which skills they should be trained towhich level with minimum training and labor cost as wellas maximum workload balance Moreover the question oftrade-off between training expenditure andworkload balancecould lead to more flexible worker assignment and cross-training policies which did not attract significant interestin previous study Besides for the question of balancingworkload of assigned workers during cross-trained workerassignment most of previous studies paid attention to flow-line manufacturing system or a single manufacturing cellThe solution of this question formultiple manufacturing cellsshould receive more concern because it is more complex andpractical due to the interplay among cells
Considering the high complexity of the NP-hard prob-lem optimization software (LINGO CPLEX) were accompa-nied with long runtime consumption Consequently efficientmetaheuristics for the models have been attracting growingattention in recent years especially swarm intelligence meta-heuristics For example ABC was employed to address theuncovering community problem in complex networks [42]and a novel PSO algorithm was utilized for power systemoptimization [43] However few researchers used the swarmintelligence metaheuristics to solve the problem of cross-trained worker assignment for multiple cells
To fill the gaps in the literature this study aimsto build a new model to address the worker assign-ment problem among multiple manufacturing cells whileincorporating cross-training planning for workload balanceand develop solutions based on the swarm intelligencealgorithms
3 Proposed Model for Cross-TrainedWorker Assignment
This section elaborates the mathematical model for theproblem of cross-trained worker assignment in CMS Weassume that part families have already been formed andthe machines have been allocated to each part family Thetype of manufacturing cell is considered a divisional cellwhere tasks are divided among several workers in accordancewith their skill levels and task time Workers cooperate andshuttle among the workstations to complete one or severaldiscrete or successive tasks [44] Based on the feature ofcellular manufacturing system several part types with similaroperations form a part family which are processed by a groupof machines and workers in each manufacturing cell Thatmeans tasks for processing different part types in a cell aresimilar In this paper we consider skill as workerrsquos capabilityon assigned task including machine and hand operationsSome other operational assumptions and statements arestated as follows
(i) The initial skill level of each worker is given(ii)The processing time for each task for each part type is
known(iii) Each worker is assigned just to one cell(iv) Each task is assigned just to one worker(v) Machine breakdown and absenteeism are not consid-
ered(vi) All materials are delivered on time(vii) Training time is not considered(viii) The training cost of each worker for each task
depends on the task type and the skill level but not on the parttypes For instance part types 1 and 2 include task 1 which ishandled by worker 1 in a cell Training cost of worker 1 justdepends on task 1 but not on the part type
(ix) Each worker can handle all part types that arrive athis or her task stations
31 Model Notations Table 2 summarizes the index setsparameters and variables used in the proposed model
32 Mathematical Formulation The cross-trained workerassignment problem for multiple cells in CMS can be for-mulated as a nonlinear 0ndash1 integer programming model asfollows
119872119894119899 = 1205871 lowast119862
sum119888=1
119870
sum119896=1
119869
sum119895=1
119871
sum119897=1
(119908119897 minus119882119896119895) lowast 119879119862119895 lowast 119885119888119896119897119895 (1)
+1205872 lowast 120572 lowast119862
sum119888=1
119882119861119888 lowast sum119870119896=1119873119888119896sum119870119896=1119882119871119896 lowast 119873119888119896
(2)
+119862
sum119888=1
119870
sum119896=1
119873119888119896 lowast119872 (3)
subject to119870
sum119896=1
119910119888119896119895 = 1 for forall119888 119895 satisfying119875
sum119901=1
119879119888119901119895 gt 0 (4)
Mathematical Problems in Engineering 5
Table1Th
eclassificatio
nof
relatedliterature
Author
Manufacturin
gsystem
type
Num
bero
fcells
Skill
level
Cross-T
raining
Workloadbalance
Datan
ature
Solvingmetho
dHop
petal[13]
FLMS
radicradic
Stochastic
Heuris
ticPo
licies
Inman
etal[6]
FLMS
radicStochastic
Simulation
Moreira
etal[14]
FLMS
radicCertain
HGA
Mutluetal[5]
FLMS
radicCertain
IGA
Saidi-M
ehrabadetal[16]
FLMS
radicradic
Stochastic
LINGO
Sung
urandYavu
zetal[17]
FLMS
radicCertain
CPLE
XParvin
etal[15]
FLMS
radicradic
Stochastic
Heuris
ticPo
licies
Aryanezhadetal[18]
CMS
Multip
leradic
radicCertain
LINGO
Mahdavietal[19]
CMS
Multip
leCertain
LINGO
Mahdavietal[20]
CMS
Multip
leCertain
LINGO
Bagh
eriand
Bashiri
[32]
CMS
Multip
leradic
Stochastic
LINGO
Niakanetal[22]
CMS
Multip
leradic
radicStochastic
NSG
AII-
MOSA
Liuetal[1]
CMS
Multip
leStochastic
DBF
ALiuetal[23]
CMS
Multip
leradic
Certain
HBF
AAskin
andHuang
[24]
CMS
Multip
leradic
radicStochastic
Greedyheuristic
Norman
etal[25]
CMS
Sing
leradic
radicStochastic
CPLE
XErtayandRu
an[26]
CMS
Sing
leStochastic
DEA
FitzpatrickandAskin
[27]
CMS
Sing
leradic
Stochastic
Balanced
placem
enth
euris
ticCesaniand
Steudel[28]
CMS
Sing
leradic
Certain
Simulation
Suer
andTu
mmaluri[33]
CMS
Sing
leradic
Stochastic
Max
andMaxMin
heuristic
McD
onaldetal[29]
CMS
Sing
leradic
radicCertain
CPLE
XMuralietal[30]
CMS
Multip
leradic
radicCertain
ANN
Egilm
ezetal[31]
CMS
Multip
leradic
Certain
LINGO
6 Mathematical Problems in Engineering
Table 2 Model notations and definitions
Index sets Definitions119888 Index of cells (119888 = 1 2 119862)119901 Index of parts (119901 = 1 2 119875)119895 Index of tasks (119895 = 1 2 119869)119896 Index of workers (119896 = 1 2 119870)119897 Index of skill levels (119897 = 1 2 119871)Parameters Definitions119862 Number of cells119875 Number of parts119869 Number of tasks119870 Number of workers119871 Number of skill levels119879119862119895 Training cost of task 119895119879119888119901119895 Standard processing time of part type 119901 at task 119895 in cell 119888119889119888119901119895 Required throughput of part type 119901 at task 119895 in cell 119888 in one shift119882119896119895 Initial skill level weight of worker k at task 119895119908119897 Weight of skill level 119897119867 Available working time in one shift119881 Maximum permissible training cost120572 Penalty cost of workload imbalance119872 Large value1205871 1205872 Weight factorsVariables Definitions119885119888119896119897119895 1 if worker k with skill level l will be assigned to task j in cell c 0 otherwise119910119888119896119895 1 if worker k will be assigned to task j in cell c 0 otherwise119873119888119896 1 if worker k will be assigned into cell c 0 otherwise119882119871119896 Workload of worker k119882119861119888 Workload of bottleneck worker in cell c
119870
sum119896=1
119910119888119896119895 = 0 for forall119888 119895 satisfying119875
sum119901=1
119879119888119901119895 = 0 (5)
119873119888119896 = 1 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 ge 1 (6)
119873119888119896 = 0 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 = 0 (7)
119862
sum119888=1
119873119888119896 le 1 forall119896 (8)
119871
sum119897=1
119885119888119896119897119895 = 119910119888119896119895 forall119888 119896 119895 (9)
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119885119888119896119897119895 lowast 119879119888119901119895 lowast 119889119888119901119895119908119897
le 119867 forall119888 119896 (10)
119882119871119896 =119862
sum119888=1
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119879119888119901119895 lowast 119885119888119896119897119895 lowast 119889119888119901119895119908119897 lowast 119867
forall119896 (11)
119882119861119888 = max119896isin(12119870)
(119882119871119896 lowast 119873119888119896) forall119888 (12)
119871
sum119897=1
119885119888119896119897119895 lowast 119908119897 ge 119910119888119896119895 lowast119882119896119895 forall119888 119896 119895 (13)
119862
sum119888=1
119870
sum119896=1
119869
sum119895=1
119871
sum119897=1
(119908119897 minus119882119896119895) lowast 119879119862119895 lowast 119885119888119896119897119895 le 119881 (14)
119910119888119896119895 119873119888119896 119885119888119896119897119895 = 0 119900119903 1 forall119888 119896 119897 119895 (15)
The first part of the above objective function is tominimize total skill training cost of the needed workers Themodel set skill level varies according to standard task timeA higher skill level refers to the worker needing less time tofinish the assigned task The cost increases when the workeris trained from a lower skill level to a higher one
The second part of the objective function is to minimizethe penalty cost of workload imbalance ie to maximizeworkload balance of assigned workers in each cell Thepenalty cost forces workload balance by reasonable workerassignment and cross-training 1205871 and 1205872 display the trade-off between training expenditure and workload balance Arelatively lower value of 1205871 and a higher value of 1205872 standfor the situation that training is recommended strongly formore exact workload balance but is accompanied with moreexpenditure Conversely a relatively higher value of 1205871 and a
Mathematical Problems in Engineering 7
lower value of 1205872 stand for the situation that training is notrecommended for less expenditure but is accompanied withless exact workload balance The decision-maker could setthe value of 1205871 and 1205872 according to the recommendation oftraining for skill level enhancement
The third part focuses on minimizing the number ofassigned workers Considering the current economic envi-ronment where labor cost is rapidly increasing this researchconsiders theminimumnumber of workers as the top priorityin the model
Constraints (4) and (5) ensure that all tasks should beallocated to the workers Constraints (6) and (7) guaranteethat one worker can handle more than one task Constraint(8) ensures that one worker could not be assigned to morethan one cell Constraint (9) guarantees that worker assignedto a task with one and only skill level Constraint (10) ensuresthat the customer demand is met Constraint (11) calculatesworkload of each assigned worker Constraint (12) definesworkload of the bottleneck worker in cell Constraint (13)ensures that the skill level of the assigned worker is not lessthan its initial level Constraint (14) ensures that the totalwork training cost does not exceed budget
4 Swarm Intelligence Metaheuristics forWorker Assignment
In this section two classical PSO variants ie GPSO andLPSO and ABC are introduced briefly Next we presentthe STABC with enhanced learning strategy to improvecomputational performanceThis is followed by the designedimplementations of the algorithms for the mathematicalmodel
41 Particle Swarm Optimization Particle swarm opti-mization (PSO) is a stochastic swarm-based metaheuristicinspired by the group behaviors of bird flocking and fishingschooling [11] In PSO a group of particles are employed tocollaboratively explore the problem landscape Each particlehas velocity and position information and moves towardsits historical best position in conjunction with populationbest position found so far Supposing that searching space isD-dimensional the m-th particlersquos velocity and position areupdated as follows
119901V119889119898 = 119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119892119887119890119904119905119889119898 minus 119883119889119898)
(16)
119883119889119898 = 119883119889119898 + 119901V119889119898 (17)
where 1199031 and 1199032 are two positive constriction coefficients1199031198861198991198891198891 and 1199031198861198991198891198892 are two random numbers between [0 1]119883119898 = (1198831119898 1198832119898 119883119863119898) is the position of particle m 119901V119898 =(119901V1119898 119901V2119898 119901V119863119898) is the velocity of particle m 119901119887119890119904119905119898 =(1199011198871198901199041199051119898 1199011198871198901199041199052119898 119901119887119890119904119905119863119898) is the best previous position forparticle m and 119892119887119890119904119905119898 = (1198921198871198901199041199051119898 1198921198871198901199041199052119898 119892119887119890119904119905119863119898) is thebest position discovered by the population so far
Global topology Local topology
Figure 1 Global and local topology structure
Many variants of PSO have been studied since theinception [45 46] A standard version is presented in [32]The standard PSO employs constricted factor 120594 as shown inthe following to guide population search
120594 = 210038161003816100381610038161003816100381610038162 minus 120593 minus radic1205932 minus 4120593
1003816100381610038161003816100381610038161003816 120593 = 1199031 + 1199032 (18)
where 1199031 and 1199032 are set to be constants to ensure the speed ofconvergence [45] With the constriction factor the originalvelocity equation is given as follows
119901V119889119898 = 120594 (119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119871119864119889119898 minus 119883119889119898))
(19)
where LEd represents the previous best information in pop-ulation It is GPSO when a neighbor could be anyone withinthe population otherwise it is LPSO The structures of thetwo patterns are shown in Figure 1The general procedures ofPSO are given as follows
(1) Initialize population size of particle swarm maxi-mum number of iterations and the constants (r1 andr2)
(2) Randomly generate a swarm of particles and initializethe velocity and position of each particle in the searchboundary
(3) Evaluate each particlersquos fitness value(4) Renew particlersquos personal best by comparing current
best information with its historical best information(5) Update the swarm best information using the best
neighborsrsquo information in population(6) Each particle updates its velocity by (19)(7) Each particle updates its position by (17)(8) Go to (3) if the stop criteria are not met otherwise
terminate the iteration
42 Artificial Bee Colony Algorithm Artificial bee colony(ABC) algorithm is inspired by the foraging behaviors in ahoney bee swarm for real-parameter optimization [12] InABC there are three types of bees employed bees onlooker
8 Mathematical Problems in Engineering
bees and scout bees The goal of the whole bees is tocollaboratively find the largest source of nectar The actuallocation of the food source represents a possible solution forthe optimization problems in ABC and the density of nectarcorresponds to a fitness value of solutionThenumber of foodsources represents the swarm size PS
In the iteration each employed bee explores the foodsource using the following
119887V119889119898 = 119909119889119898 + 120601119889119898 (119909119889119898 minus 119909119889119902) 119898 = 119902 (20)
where 119887V119889119898 denotes a candidate food source positionmm= 12 PS 120601119889119898 is a randomly produced value within [-1 1] 119909119889119898refers to the corresponding food source and 119909119889119902 is a randomlyselected food source
Each onlooker bee randomly selects its food sourcem for further refinement with a probability 119901119898 which isdetermined as follows
119901119898 =119891119894119905119899119890119904119904119898
sum119878119904=1 119891119894119905119899119890119904119904119904(21)
where119891119894119905119899119890119904119904119898 is the quality of them-th food source For theminimization problem the 119891119894119905119899119890119904119904119898 can be calculated usingthe following
119891119894119905119899119890119904119904119898 =
1(1 + 119891119898)
if 119891119898 ge 01 + 119886119887119904 (119891119898) if 119891119898 le 0
(22)
where 119891119898 is the m-th objective function value The value ofldquolimitrdquo to abandon the poor food source is suggested to be setto PSlowastD [47] The main steps of ABC are given below
(1) Initialize the number of food sources the limit andthe maximum number of iterations
(2) Randomly generate the positions of food sources inproblem landscape
(3) Evaluate the fitness value of food sources foundcurrently
(4) Each employed bee explores between a randomexem-plar and their own food source using (20)
(5) Apply greedy selection process to select the best PSpositions and record the updated food sources
(6) Calculate the probability of the food sources withwhich onlooker bees are going to follow by (21)
(7) Produce new solutionusing (20) for the onlooker beesdepending on 119901119894
(8) Conduct greedy selection and update food sourceinformation for onlooker bees
(9) Abandon the food sources with poor nectar and letscouts search for new food sources
(10) Terminate if the stop criteria are met otherwise go to(4)
43 Superior Tracking Artificial Bee Colony Algorithm Asa newly proposed algorithm while promising ABC stillsuffers from two weaknesses First the convergence speed isrelatively slow compared tomany existing swarm intelligencealgorithms Second the capability of exploring global optimais still underperforming on many multimodal problems [48]In the original search behavior of ABC only one dimensionof a bee is selected to learn and renew in each round ofinformation updating This search rule may result in the slowconvergence or inferior exploring capability [49] To addressthis issue the STABC is introduced to improve the searchcapability and convergence speed for global optimization
In STABC the employed bees and onlooker bees areupdated in accordance with the following equation
119887V119898 = 119909119898 + 119903119898 (119909119898 minus 119878119873119898) (23)
where 119887V119898 represents the food position of the m-th (m=1 2 PS) food source to be updated 119903119898 refers to arandomly generated D-dimensional vector and SN is the D-dimensional constructed exemplar for tracking in which theelements are either from itself or from the other superiorfood sources randomly chosen by roulette selection andtournament selection
The detailed procedure of constructing SNm is presentedas follows
(1) Initialize a given probability Pr to decide whichexemplar the current bee should chase itself or theother superior neighbors in the population
(2) For each dimension of 119878119873119889119898 (d = 1 toD) a valuewithin[0 1] is randomly generated(3) If the generated value is larger than Pr two food
positions are randomly chosen for comparison andthe d-th dimension of the better one will be learnedotherwise 119878119873119889119898 will be itself
(4) Repeat the above steps till all dimensions of SNm aredetermined
In STABC all elements of an individual will be likely toupdate at each iteration As a result each bee either exploitsthe local optima by learning from itself or explores the globallandscape by chasing the other individuals in the populationThis search strategy accelerates the convergence speeds ofthe population In addition it remains from ABC originalproperties that every individual could be learning exemplarsFigure 2 displays the flow chart of the STABC algorithm
44 Implementation of the SI-Based Optimizers for Cell For-mation In the proposed mathematical model the computa-tional complexity is dependent on the variable size of 119885119888119896119897119895which is equal to 119888 lowast 119896 lowast 119897 lowast 119895 The search dimension ofsolutionZcklj will be too large to optimize using the traditionalmathematical methods Our preliminary experiment indi-cates that it is extremely hard to obtain a suboptimum if thevariables are without proper treatment Meanwhile a feasiblesolution Z would be hard to locate due to the complexityand discontinuity of constraints To address these issues a SI-based metaheuristic is proposed to explore the global optima
Mathematical Problems in Engineering 9
Begin
Initialize food source positions Setting criteria and itc = 1
Fitness value calculation
Evaluate new solution
Greedy SelectionCalculate the probability
of the food source
Determine the chosenfood source by the
onlooker bees
Output
N
Y
itc gt criteria
itc = itc+1
Greedy SelectionRandomly generate a new
position for the abandonedfood sources
Evaluate new solution
itc iteration counter
Trial successfully update record of each food source
Pr a threshold
randi an interger from a uniform discrete distribution
FS the position of the food sources
FV fitness value
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Figure 2 Flowchart of the STABC algorithm
While implementing the swarm-based optimizers for cross-trained worker assignment problem three important issuesshould be considered encoding decoding and constrainshandling
An effective encoding method is developed in this studyThe original 0-1 planning problem is transformed into aninteger programming problem in which the targeting skilllevel and theworker are allocated to each task tomeet the pro-duction requirements For the population initialization them-th individual is represented as 119909119898 = [1199091198981 1199091198982 119909119898119895]j = 1 2 J where J denotes the value of tasks The range ofthe algorithmic representation 1199091198981 is [1 k+l]
In the decoding process the worker and skill levelindices need to be determined through the algorithmicrepresentation A cross-reference matrix is generated here forconverting individual 119909119898 to the indices of worker and skilllevel Details of procedures involved in the decoding processfor 119909119898 are shown in Figure 3
For the constraints handling process the basic penaltyfunctionmethod is adopted [50] Once the objective functionvalue of 119909119898 and the corresponding constraint violation havebeen obtained the penalty value is added to the objectivefunction value of 119909119898
Begin
Y
1 2 hellip K1 1 2 hellip K2 hellip hellip hellip helliphellip hellip hellip hellip hellipL hellip hellip hellip K+L N
Y
Y
N
c = 1 j = 1empty Zcklj
p = 1P
Cross-reference
Inputxmj
Outputindexvalue
kl
Z(cklj) = 1j = j+1
j gt J
c = c+1j =1
c gt C
Output Zcklj
any(Tcpj)gt0
Figure 3 Decoding procedure
5 Computational Experiment
To validate effectiveness and efficiency of the proposedmathematical model and optimizers computational ex-periments are performed in this section Ten problemsare randomly generated based on previous research(can be accessed at httpsdrivegooglecomopenid=0B18FVuMxAffXLW1mRzVLczlyem8) The experiments areimplemented using MATLAB R2012a and the desktop iswith Intel Core i5 CPU 320GHz and 8GB memory
51 Experiment Settings The cross-trained worker assign-ment problem is based on the formed manufacturing cellsin this research that is part and tasks types had beenfixed after cell formation in CMS Ten cell formation prob-lems are selected from previous literature (see Table 3) Asthe problems are generated with different sizes they arenot directly correlated to each other The different typesof problem size can comprehensively evaluate the scalableperformance of the proposed method on this mathematical
10 Mathematical Problems in Engineering
Table 3 Dimension of test problems
Problem No Number ofParts Tasks Cells Workers
P1 [34] 5 5 2 5P2 [35] 7 5 2 5P3 [36] 6 6 2 6P4 [37] 8 9 2 9P5 [38] 10 8 3 8P6 [36] 8 10 3 10P7 [39] 10 10 3 10P8 [35] 12 10 3 10P9 [40] 18 10 3 10P10 [41] 22 11 3 11
Table 4 Pattern of data generation
Parameters Values119879119862119895 lowastDU(500 1000)119879119888119901119895 DU(01 15)119889119888119901119895 DU(50 150)119882119896119895 Randomly generated in set (0 07 08 09 1 11)119908119897 w1=07 w2=08 w3=09 w4=10 w5=11lowastDU(m n) means discrete uniform distribution varying between m and nThe unit of time is minute
model The additional parameters are randomly generatedas shown in Table 4 To allow one-to-one correspondencebetween workers and tasks in extreme situation we assumedthat the number of available workers is equal to the numberof tasks in CMS The available working time of each workerin a shift is calculated as 8 hlowast60mlowast85=408m The trainingbudget in the factory is sufficient Penalty cost of workloadimbalance 120572 is assumed to be 100 With respect to the trade-off between training expenditure and workload balanceldquo1205871=1 1205872=10rdquo stands for the first situation which refers tothe pursuit of more exact workload balance although moretraining cost should be spent while ldquo1205871=10 1205872=1rdquo standsfor the second situation which refers to saving training costalthough workload balance may not be enforced very well
Themaximum number of iterations is set as 20000 whereall the candidate algorithms are found to converge fast Forthe standard PSO the constant120593=41 and the values120594=07298and r1=r2=205 are gathered (Bratton and Kennedy 2007)For the STABC the range of 119903119898 is empirically set as [0149] which could be a time-varying function as well [49]With respect to the threshold probability Pr of STABC themethod introduced in Liang et alrsquos research [51] is adoptedThe population size is set at 30 for all algorithms [47]
52 Experimental Results Each problem is run indepen-dently 20 times with the four algorithms (GPSO LPSO ABCand STABC) The CPU time for each run does not exceed90s In Table 5 119874119865119881119887 119874119865119881119908 and 119874119865119881119886 represent the bestworst and average objective function values (OFV) of theten problems after 20 runs under the two situations (1205871=1
0
25000
50000
75000
100000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=1 2=10
GPSOLPSO
ABCSTABC
Figure 4 119874119865119881119887 results for the case of 1205871=1 1205872=10
1205872=10) and (1205871=10 1205872=1)The best solutions of119874119865119881119887119874119865119881119908and 119874119865119881119886 found by the four algorithms are shown in boldBased on experimental results three measures to evaluate theeffectiveness of STABC algorithm are defined as follows(1) 119861119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119887 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119861119866119866119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119887byGPSO over 119874119865119881119887 by STABC(2) 119882119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119908between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance119882119866119871119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119908 byLPSO over 119874119865119881119908 by STABC(3) 119860119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119886 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119860119866119860119861119862119878119879119860119861119862 means the rising percentage of 119874119865119881119886 byABC over 119874119865119881119886 by STABC
With respect to the abovemeasures the presented STABCis employed as the basis to compare the performance of theinvolved algorithms A positive value indicates that STABCoutperforms the other algorithms on the optimized problem
Table 6 shows the comparison results on the ten problemsunder the two situations (1205871=1 1205872=10) and (1205871=10 1205872=1) Wesee thatmost of119861119866lowast119878119879119860119861119862119882119866lowast119878119879119860119861119862119860119866lowast119878119879119860119861119862 and all averagevalues are positive Thus better results with respect to119874119865119881119887119874119865119881119908 and 119874119865119881119886 can be attained by STABC compared toGPSO LPSO and ABC under both situations (1205871=1 1205872=10)and (1205871=10 1205872=1)
Figures 4 and 5 compare the 119874119865119881119887obtained by GPSOLPSO ABC and STABC (see Table 5)They demonstrate thatthe best solutions of STABC are better than the others Forthe relatively simple small-size problems such as problems1 2 and 3 most of the algorithms can easily identify thebest results With the increase of problem size STABCoutperforms the other algorithms on the relatively large-sizeproblems The improvement of STBACrsquos search capabilitycan be attributed to two properties (1) each individualrsquoslearning speed for exploration is improved by learning fromother bees in all dimensions and (2) the individualrsquos learningsources for exploitation are enriched by learning fromboth itshistorical information and the superior individualsThenovelstrategies can significantly enhance the global exploration
Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
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4 Mathematical Problems in Engineering
assignment arising in a lean manufacturing cell The modelsought minimum cost of training inventory and poor qualityto determine skill training necessary for workers to meettasks and customer demand Their study also proposed theaddition of pay-for-skills reward in evaluating the costs andbenefits of cross-training However their study had onlyfocused on worker assignment for a single cell althoughmultiple cells exist in the CMS Murali et al [30] developedan artificial neural network model for assigning workforce invirtual cells under dual resource constrained context wherethe number of available workers is less than total numberof available machines Egilmez et al [31] developed a four-phased hierarchical methodology to address the stochasticskill-based manpower allocation problem In their studyworkerrsquos expected processing time and the standard deviationfor each operation were considered individually to optimizethe worker assignment to cells and maximize the productionrate of manufacturing system Table 1 presents a classificationof the previous studies
The aforementioned studies had pointed out that workerassignment plays an essential role in both flow-line andcellular manufacturing system To explore the problemof workload balance among assigned workers the cross-training strategy has been examined widely However mostof previous studies just determined which worker shouldbe trained for which task The question of an effectivestrategy of need for cross-training by prioritizing exact skilllevel of worker to avoid excessive training was ignoredThat is very few achievements specifically indicated howmany workers and in which skills they should be trained towhich level with minimum training and labor cost as wellas maximum workload balance Moreover the question oftrade-off between training expenditure andworkload balancecould lead to more flexible worker assignment and cross-training policies which did not attract significant interestin previous study Besides for the question of balancingworkload of assigned workers during cross-trained workerassignment most of previous studies paid attention to flow-line manufacturing system or a single manufacturing cellThe solution of this question formultiple manufacturing cellsshould receive more concern because it is more complex andpractical due to the interplay among cells
Considering the high complexity of the NP-hard prob-lem optimization software (LINGO CPLEX) were accompa-nied with long runtime consumption Consequently efficientmetaheuristics for the models have been attracting growingattention in recent years especially swarm intelligence meta-heuristics For example ABC was employed to address theuncovering community problem in complex networks [42]and a novel PSO algorithm was utilized for power systemoptimization [43] However few researchers used the swarmintelligence metaheuristics to solve the problem of cross-trained worker assignment for multiple cells
To fill the gaps in the literature this study aimsto build a new model to address the worker assign-ment problem among multiple manufacturing cells whileincorporating cross-training planning for workload balanceand develop solutions based on the swarm intelligencealgorithms
3 Proposed Model for Cross-TrainedWorker Assignment
This section elaborates the mathematical model for theproblem of cross-trained worker assignment in CMS Weassume that part families have already been formed andthe machines have been allocated to each part family Thetype of manufacturing cell is considered a divisional cellwhere tasks are divided among several workers in accordancewith their skill levels and task time Workers cooperate andshuttle among the workstations to complete one or severaldiscrete or successive tasks [44] Based on the feature ofcellular manufacturing system several part types with similaroperations form a part family which are processed by a groupof machines and workers in each manufacturing cell Thatmeans tasks for processing different part types in a cell aresimilar In this paper we consider skill as workerrsquos capabilityon assigned task including machine and hand operationsSome other operational assumptions and statements arestated as follows
(i) The initial skill level of each worker is given(ii)The processing time for each task for each part type is
known(iii) Each worker is assigned just to one cell(iv) Each task is assigned just to one worker(v) Machine breakdown and absenteeism are not consid-
ered(vi) All materials are delivered on time(vii) Training time is not considered(viii) The training cost of each worker for each task
depends on the task type and the skill level but not on the parttypes For instance part types 1 and 2 include task 1 which ishandled by worker 1 in a cell Training cost of worker 1 justdepends on task 1 but not on the part type
(ix) Each worker can handle all part types that arrive athis or her task stations
31 Model Notations Table 2 summarizes the index setsparameters and variables used in the proposed model
32 Mathematical Formulation The cross-trained workerassignment problem for multiple cells in CMS can be for-mulated as a nonlinear 0ndash1 integer programming model asfollows
119872119894119899 = 1205871 lowast119862
sum119888=1
119870
sum119896=1
119869
sum119895=1
119871
sum119897=1
(119908119897 minus119882119896119895) lowast 119879119862119895 lowast 119885119888119896119897119895 (1)
+1205872 lowast 120572 lowast119862
sum119888=1
119882119861119888 lowast sum119870119896=1119873119888119896sum119870119896=1119882119871119896 lowast 119873119888119896
(2)
+119862
sum119888=1
119870
sum119896=1
119873119888119896 lowast119872 (3)
subject to119870
sum119896=1
119910119888119896119895 = 1 for forall119888 119895 satisfying119875
sum119901=1
119879119888119901119895 gt 0 (4)
Mathematical Problems in Engineering 5
Table1Th
eclassificatio
nof
relatedliterature
Author
Manufacturin
gsystem
type
Num
bero
fcells
Skill
level
Cross-T
raining
Workloadbalance
Datan
ature
Solvingmetho
dHop
petal[13]
FLMS
radicradic
Stochastic
Heuris
ticPo
licies
Inman
etal[6]
FLMS
radicStochastic
Simulation
Moreira
etal[14]
FLMS
radicCertain
HGA
Mutluetal[5]
FLMS
radicCertain
IGA
Saidi-M
ehrabadetal[16]
FLMS
radicradic
Stochastic
LINGO
Sung
urandYavu
zetal[17]
FLMS
radicCertain
CPLE
XParvin
etal[15]
FLMS
radicradic
Stochastic
Heuris
ticPo
licies
Aryanezhadetal[18]
CMS
Multip
leradic
radicCertain
LINGO
Mahdavietal[19]
CMS
Multip
leCertain
LINGO
Mahdavietal[20]
CMS
Multip
leCertain
LINGO
Bagh
eriand
Bashiri
[32]
CMS
Multip
leradic
Stochastic
LINGO
Niakanetal[22]
CMS
Multip
leradic
radicStochastic
NSG
AII-
MOSA
Liuetal[1]
CMS
Multip
leStochastic
DBF
ALiuetal[23]
CMS
Multip
leradic
Certain
HBF
AAskin
andHuang
[24]
CMS
Multip
leradic
radicStochastic
Greedyheuristic
Norman
etal[25]
CMS
Sing
leradic
radicStochastic
CPLE
XErtayandRu
an[26]
CMS
Sing
leStochastic
DEA
FitzpatrickandAskin
[27]
CMS
Sing
leradic
Stochastic
Balanced
placem
enth
euris
ticCesaniand
Steudel[28]
CMS
Sing
leradic
Certain
Simulation
Suer
andTu
mmaluri[33]
CMS
Sing
leradic
Stochastic
Max
andMaxMin
heuristic
McD
onaldetal[29]
CMS
Sing
leradic
radicCertain
CPLE
XMuralietal[30]
CMS
Multip
leradic
radicCertain
ANN
Egilm
ezetal[31]
CMS
Multip
leradic
Certain
LINGO
6 Mathematical Problems in Engineering
Table 2 Model notations and definitions
Index sets Definitions119888 Index of cells (119888 = 1 2 119862)119901 Index of parts (119901 = 1 2 119875)119895 Index of tasks (119895 = 1 2 119869)119896 Index of workers (119896 = 1 2 119870)119897 Index of skill levels (119897 = 1 2 119871)Parameters Definitions119862 Number of cells119875 Number of parts119869 Number of tasks119870 Number of workers119871 Number of skill levels119879119862119895 Training cost of task 119895119879119888119901119895 Standard processing time of part type 119901 at task 119895 in cell 119888119889119888119901119895 Required throughput of part type 119901 at task 119895 in cell 119888 in one shift119882119896119895 Initial skill level weight of worker k at task 119895119908119897 Weight of skill level 119897119867 Available working time in one shift119881 Maximum permissible training cost120572 Penalty cost of workload imbalance119872 Large value1205871 1205872 Weight factorsVariables Definitions119885119888119896119897119895 1 if worker k with skill level l will be assigned to task j in cell c 0 otherwise119910119888119896119895 1 if worker k will be assigned to task j in cell c 0 otherwise119873119888119896 1 if worker k will be assigned into cell c 0 otherwise119882119871119896 Workload of worker k119882119861119888 Workload of bottleneck worker in cell c
119870
sum119896=1
119910119888119896119895 = 0 for forall119888 119895 satisfying119875
sum119901=1
119879119888119901119895 = 0 (5)
119873119888119896 = 1 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 ge 1 (6)
119873119888119896 = 0 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 = 0 (7)
119862
sum119888=1
119873119888119896 le 1 forall119896 (8)
119871
sum119897=1
119885119888119896119897119895 = 119910119888119896119895 forall119888 119896 119895 (9)
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119885119888119896119897119895 lowast 119879119888119901119895 lowast 119889119888119901119895119908119897
le 119867 forall119888 119896 (10)
119882119871119896 =119862
sum119888=1
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119879119888119901119895 lowast 119885119888119896119897119895 lowast 119889119888119901119895119908119897 lowast 119867
forall119896 (11)
119882119861119888 = max119896isin(12119870)
(119882119871119896 lowast 119873119888119896) forall119888 (12)
119871
sum119897=1
119885119888119896119897119895 lowast 119908119897 ge 119910119888119896119895 lowast119882119896119895 forall119888 119896 119895 (13)
119862
sum119888=1
119870
sum119896=1
119869
sum119895=1
119871
sum119897=1
(119908119897 minus119882119896119895) lowast 119879119862119895 lowast 119885119888119896119897119895 le 119881 (14)
119910119888119896119895 119873119888119896 119885119888119896119897119895 = 0 119900119903 1 forall119888 119896 119897 119895 (15)
The first part of the above objective function is tominimize total skill training cost of the needed workers Themodel set skill level varies according to standard task timeA higher skill level refers to the worker needing less time tofinish the assigned task The cost increases when the workeris trained from a lower skill level to a higher one
The second part of the objective function is to minimizethe penalty cost of workload imbalance ie to maximizeworkload balance of assigned workers in each cell Thepenalty cost forces workload balance by reasonable workerassignment and cross-training 1205871 and 1205872 display the trade-off between training expenditure and workload balance Arelatively lower value of 1205871 and a higher value of 1205872 standfor the situation that training is recommended strongly formore exact workload balance but is accompanied with moreexpenditure Conversely a relatively higher value of 1205871 and a
Mathematical Problems in Engineering 7
lower value of 1205872 stand for the situation that training is notrecommended for less expenditure but is accompanied withless exact workload balance The decision-maker could setthe value of 1205871 and 1205872 according to the recommendation oftraining for skill level enhancement
The third part focuses on minimizing the number ofassigned workers Considering the current economic envi-ronment where labor cost is rapidly increasing this researchconsiders theminimumnumber of workers as the top priorityin the model
Constraints (4) and (5) ensure that all tasks should beallocated to the workers Constraints (6) and (7) guaranteethat one worker can handle more than one task Constraint(8) ensures that one worker could not be assigned to morethan one cell Constraint (9) guarantees that worker assignedto a task with one and only skill level Constraint (10) ensuresthat the customer demand is met Constraint (11) calculatesworkload of each assigned worker Constraint (12) definesworkload of the bottleneck worker in cell Constraint (13)ensures that the skill level of the assigned worker is not lessthan its initial level Constraint (14) ensures that the totalwork training cost does not exceed budget
4 Swarm Intelligence Metaheuristics forWorker Assignment
In this section two classical PSO variants ie GPSO andLPSO and ABC are introduced briefly Next we presentthe STABC with enhanced learning strategy to improvecomputational performanceThis is followed by the designedimplementations of the algorithms for the mathematicalmodel
41 Particle Swarm Optimization Particle swarm opti-mization (PSO) is a stochastic swarm-based metaheuristicinspired by the group behaviors of bird flocking and fishingschooling [11] In PSO a group of particles are employed tocollaboratively explore the problem landscape Each particlehas velocity and position information and moves towardsits historical best position in conjunction with populationbest position found so far Supposing that searching space isD-dimensional the m-th particlersquos velocity and position areupdated as follows
119901V119889119898 = 119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119892119887119890119904119905119889119898 minus 119883119889119898)
(16)
119883119889119898 = 119883119889119898 + 119901V119889119898 (17)
where 1199031 and 1199032 are two positive constriction coefficients1199031198861198991198891198891 and 1199031198861198991198891198892 are two random numbers between [0 1]119883119898 = (1198831119898 1198832119898 119883119863119898) is the position of particle m 119901V119898 =(119901V1119898 119901V2119898 119901V119863119898) is the velocity of particle m 119901119887119890119904119905119898 =(1199011198871198901199041199051119898 1199011198871198901199041199052119898 119901119887119890119904119905119863119898) is the best previous position forparticle m and 119892119887119890119904119905119898 = (1198921198871198901199041199051119898 1198921198871198901199041199052119898 119892119887119890119904119905119863119898) is thebest position discovered by the population so far
Global topology Local topology
Figure 1 Global and local topology structure
Many variants of PSO have been studied since theinception [45 46] A standard version is presented in [32]The standard PSO employs constricted factor 120594 as shown inthe following to guide population search
120594 = 210038161003816100381610038161003816100381610038162 minus 120593 minus radic1205932 minus 4120593
1003816100381610038161003816100381610038161003816 120593 = 1199031 + 1199032 (18)
where 1199031 and 1199032 are set to be constants to ensure the speed ofconvergence [45] With the constriction factor the originalvelocity equation is given as follows
119901V119889119898 = 120594 (119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119871119864119889119898 minus 119883119889119898))
(19)
where LEd represents the previous best information in pop-ulation It is GPSO when a neighbor could be anyone withinthe population otherwise it is LPSO The structures of thetwo patterns are shown in Figure 1The general procedures ofPSO are given as follows
(1) Initialize population size of particle swarm maxi-mum number of iterations and the constants (r1 andr2)
(2) Randomly generate a swarm of particles and initializethe velocity and position of each particle in the searchboundary
(3) Evaluate each particlersquos fitness value(4) Renew particlersquos personal best by comparing current
best information with its historical best information(5) Update the swarm best information using the best
neighborsrsquo information in population(6) Each particle updates its velocity by (19)(7) Each particle updates its position by (17)(8) Go to (3) if the stop criteria are not met otherwise
terminate the iteration
42 Artificial Bee Colony Algorithm Artificial bee colony(ABC) algorithm is inspired by the foraging behaviors in ahoney bee swarm for real-parameter optimization [12] InABC there are three types of bees employed bees onlooker
8 Mathematical Problems in Engineering
bees and scout bees The goal of the whole bees is tocollaboratively find the largest source of nectar The actuallocation of the food source represents a possible solution forthe optimization problems in ABC and the density of nectarcorresponds to a fitness value of solutionThenumber of foodsources represents the swarm size PS
In the iteration each employed bee explores the foodsource using the following
119887V119889119898 = 119909119889119898 + 120601119889119898 (119909119889119898 minus 119909119889119902) 119898 = 119902 (20)
where 119887V119889119898 denotes a candidate food source positionmm= 12 PS 120601119889119898 is a randomly produced value within [-1 1] 119909119889119898refers to the corresponding food source and 119909119889119902 is a randomlyselected food source
Each onlooker bee randomly selects its food sourcem for further refinement with a probability 119901119898 which isdetermined as follows
119901119898 =119891119894119905119899119890119904119904119898
sum119878119904=1 119891119894119905119899119890119904119904119904(21)
where119891119894119905119899119890119904119904119898 is the quality of them-th food source For theminimization problem the 119891119894119905119899119890119904119904119898 can be calculated usingthe following
119891119894119905119899119890119904119904119898 =
1(1 + 119891119898)
if 119891119898 ge 01 + 119886119887119904 (119891119898) if 119891119898 le 0
(22)
where 119891119898 is the m-th objective function value The value ofldquolimitrdquo to abandon the poor food source is suggested to be setto PSlowastD [47] The main steps of ABC are given below
(1) Initialize the number of food sources the limit andthe maximum number of iterations
(2) Randomly generate the positions of food sources inproblem landscape
(3) Evaluate the fitness value of food sources foundcurrently
(4) Each employed bee explores between a randomexem-plar and their own food source using (20)
(5) Apply greedy selection process to select the best PSpositions and record the updated food sources
(6) Calculate the probability of the food sources withwhich onlooker bees are going to follow by (21)
(7) Produce new solutionusing (20) for the onlooker beesdepending on 119901119894
(8) Conduct greedy selection and update food sourceinformation for onlooker bees
(9) Abandon the food sources with poor nectar and letscouts search for new food sources
(10) Terminate if the stop criteria are met otherwise go to(4)
43 Superior Tracking Artificial Bee Colony Algorithm Asa newly proposed algorithm while promising ABC stillsuffers from two weaknesses First the convergence speed isrelatively slow compared tomany existing swarm intelligencealgorithms Second the capability of exploring global optimais still underperforming on many multimodal problems [48]In the original search behavior of ABC only one dimensionof a bee is selected to learn and renew in each round ofinformation updating This search rule may result in the slowconvergence or inferior exploring capability [49] To addressthis issue the STABC is introduced to improve the searchcapability and convergence speed for global optimization
In STABC the employed bees and onlooker bees areupdated in accordance with the following equation
119887V119898 = 119909119898 + 119903119898 (119909119898 minus 119878119873119898) (23)
where 119887V119898 represents the food position of the m-th (m=1 2 PS) food source to be updated 119903119898 refers to arandomly generated D-dimensional vector and SN is the D-dimensional constructed exemplar for tracking in which theelements are either from itself or from the other superiorfood sources randomly chosen by roulette selection andtournament selection
The detailed procedure of constructing SNm is presentedas follows
(1) Initialize a given probability Pr to decide whichexemplar the current bee should chase itself or theother superior neighbors in the population
(2) For each dimension of 119878119873119889119898 (d = 1 toD) a valuewithin[0 1] is randomly generated(3) If the generated value is larger than Pr two food
positions are randomly chosen for comparison andthe d-th dimension of the better one will be learnedotherwise 119878119873119889119898 will be itself
(4) Repeat the above steps till all dimensions of SNm aredetermined
In STABC all elements of an individual will be likely toupdate at each iteration As a result each bee either exploitsthe local optima by learning from itself or explores the globallandscape by chasing the other individuals in the populationThis search strategy accelerates the convergence speeds ofthe population In addition it remains from ABC originalproperties that every individual could be learning exemplarsFigure 2 displays the flow chart of the STABC algorithm
44 Implementation of the SI-Based Optimizers for Cell For-mation In the proposed mathematical model the computa-tional complexity is dependent on the variable size of 119885119888119896119897119895which is equal to 119888 lowast 119896 lowast 119897 lowast 119895 The search dimension ofsolutionZcklj will be too large to optimize using the traditionalmathematical methods Our preliminary experiment indi-cates that it is extremely hard to obtain a suboptimum if thevariables are without proper treatment Meanwhile a feasiblesolution Z would be hard to locate due to the complexityand discontinuity of constraints To address these issues a SI-based metaheuristic is proposed to explore the global optima
Mathematical Problems in Engineering 9
Begin
Initialize food source positions Setting criteria and itc = 1
Fitness value calculation
Evaluate new solution
Greedy SelectionCalculate the probability
of the food source
Determine the chosenfood source by the
onlooker bees
Output
N
Y
itc gt criteria
itc = itc+1
Greedy SelectionRandomly generate a new
position for the abandonedfood sources
Evaluate new solution
itc iteration counter
Trial successfully update record of each food source
Pr a threshold
randi an interger from a uniform discrete distribution
FS the position of the food sources
FV fitness value
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Figure 2 Flowchart of the STABC algorithm
While implementing the swarm-based optimizers for cross-trained worker assignment problem three important issuesshould be considered encoding decoding and constrainshandling
An effective encoding method is developed in this studyThe original 0-1 planning problem is transformed into aninteger programming problem in which the targeting skilllevel and theworker are allocated to each task tomeet the pro-duction requirements For the population initialization them-th individual is represented as 119909119898 = [1199091198981 1199091198982 119909119898119895]j = 1 2 J where J denotes the value of tasks The range ofthe algorithmic representation 1199091198981 is [1 k+l]
In the decoding process the worker and skill levelindices need to be determined through the algorithmicrepresentation A cross-reference matrix is generated here forconverting individual 119909119898 to the indices of worker and skilllevel Details of procedures involved in the decoding processfor 119909119898 are shown in Figure 3
For the constraints handling process the basic penaltyfunctionmethod is adopted [50] Once the objective functionvalue of 119909119898 and the corresponding constraint violation havebeen obtained the penalty value is added to the objectivefunction value of 119909119898
Begin
Y
1 2 hellip K1 1 2 hellip K2 hellip hellip hellip helliphellip hellip hellip hellip hellipL hellip hellip hellip K+L N
Y
Y
N
c = 1 j = 1empty Zcklj
p = 1P
Cross-reference
Inputxmj
Outputindexvalue
kl
Z(cklj) = 1j = j+1
j gt J
c = c+1j =1
c gt C
Output Zcklj
any(Tcpj)gt0
Figure 3 Decoding procedure
5 Computational Experiment
To validate effectiveness and efficiency of the proposedmathematical model and optimizers computational ex-periments are performed in this section Ten problemsare randomly generated based on previous research(can be accessed at httpsdrivegooglecomopenid=0B18FVuMxAffXLW1mRzVLczlyem8) The experiments areimplemented using MATLAB R2012a and the desktop iswith Intel Core i5 CPU 320GHz and 8GB memory
51 Experiment Settings The cross-trained worker assign-ment problem is based on the formed manufacturing cellsin this research that is part and tasks types had beenfixed after cell formation in CMS Ten cell formation prob-lems are selected from previous literature (see Table 3) Asthe problems are generated with different sizes they arenot directly correlated to each other The different typesof problem size can comprehensively evaluate the scalableperformance of the proposed method on this mathematical
10 Mathematical Problems in Engineering
Table 3 Dimension of test problems
Problem No Number ofParts Tasks Cells Workers
P1 [34] 5 5 2 5P2 [35] 7 5 2 5P3 [36] 6 6 2 6P4 [37] 8 9 2 9P5 [38] 10 8 3 8P6 [36] 8 10 3 10P7 [39] 10 10 3 10P8 [35] 12 10 3 10P9 [40] 18 10 3 10P10 [41] 22 11 3 11
Table 4 Pattern of data generation
Parameters Values119879119862119895 lowastDU(500 1000)119879119888119901119895 DU(01 15)119889119888119901119895 DU(50 150)119882119896119895 Randomly generated in set (0 07 08 09 1 11)119908119897 w1=07 w2=08 w3=09 w4=10 w5=11lowastDU(m n) means discrete uniform distribution varying between m and nThe unit of time is minute
model The additional parameters are randomly generatedas shown in Table 4 To allow one-to-one correspondencebetween workers and tasks in extreme situation we assumedthat the number of available workers is equal to the numberof tasks in CMS The available working time of each workerin a shift is calculated as 8 hlowast60mlowast85=408m The trainingbudget in the factory is sufficient Penalty cost of workloadimbalance 120572 is assumed to be 100 With respect to the trade-off between training expenditure and workload balanceldquo1205871=1 1205872=10rdquo stands for the first situation which refers tothe pursuit of more exact workload balance although moretraining cost should be spent while ldquo1205871=10 1205872=1rdquo standsfor the second situation which refers to saving training costalthough workload balance may not be enforced very well
Themaximum number of iterations is set as 20000 whereall the candidate algorithms are found to converge fast Forthe standard PSO the constant120593=41 and the values120594=07298and r1=r2=205 are gathered (Bratton and Kennedy 2007)For the STABC the range of 119903119898 is empirically set as [0149] which could be a time-varying function as well [49]With respect to the threshold probability Pr of STABC themethod introduced in Liang et alrsquos research [51] is adoptedThe population size is set at 30 for all algorithms [47]
52 Experimental Results Each problem is run indepen-dently 20 times with the four algorithms (GPSO LPSO ABCand STABC) The CPU time for each run does not exceed90s In Table 5 119874119865119881119887 119874119865119881119908 and 119874119865119881119886 represent the bestworst and average objective function values (OFV) of theten problems after 20 runs under the two situations (1205871=1
0
25000
50000
75000
100000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=1 2=10
GPSOLPSO
ABCSTABC
Figure 4 119874119865119881119887 results for the case of 1205871=1 1205872=10
1205872=10) and (1205871=10 1205872=1)The best solutions of119874119865119881119887119874119865119881119908and 119874119865119881119886 found by the four algorithms are shown in boldBased on experimental results three measures to evaluate theeffectiveness of STABC algorithm are defined as follows(1) 119861119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119887 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119861119866119866119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119887byGPSO over 119874119865119881119887 by STABC(2) 119882119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119908between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance119882119866119871119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119908 byLPSO over 119874119865119881119908 by STABC(3) 119860119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119886 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119860119866119860119861119862119878119879119860119861119862 means the rising percentage of 119874119865119881119886 byABC over 119874119865119881119886 by STABC
With respect to the abovemeasures the presented STABCis employed as the basis to compare the performance of theinvolved algorithms A positive value indicates that STABCoutperforms the other algorithms on the optimized problem
Table 6 shows the comparison results on the ten problemsunder the two situations (1205871=1 1205872=10) and (1205871=10 1205872=1) Wesee thatmost of119861119866lowast119878119879119860119861119862119882119866lowast119878119879119860119861119862119860119866lowast119878119879119860119861119862 and all averagevalues are positive Thus better results with respect to119874119865119881119887119874119865119881119908 and 119874119865119881119886 can be attained by STABC compared toGPSO LPSO and ABC under both situations (1205871=1 1205872=10)and (1205871=10 1205872=1)
Figures 4 and 5 compare the 119874119865119881119887obtained by GPSOLPSO ABC and STABC (see Table 5)They demonstrate thatthe best solutions of STABC are better than the others Forthe relatively simple small-size problems such as problems1 2 and 3 most of the algorithms can easily identify thebest results With the increase of problem size STABCoutperforms the other algorithms on the relatively large-sizeproblems The improvement of STBACrsquos search capabilitycan be attributed to two properties (1) each individualrsquoslearning speed for exploration is improved by learning fromother bees in all dimensions and (2) the individualrsquos learningsources for exploitation are enriched by learning fromboth itshistorical information and the superior individualsThenovelstrategies can significantly enhance the global exploration
Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
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Mathematical Problems in Engineering 5
Table1Th
eclassificatio
nof
relatedliterature
Author
Manufacturin
gsystem
type
Num
bero
fcells
Skill
level
Cross-T
raining
Workloadbalance
Datan
ature
Solvingmetho
dHop
petal[13]
FLMS
radicradic
Stochastic
Heuris
ticPo
licies
Inman
etal[6]
FLMS
radicStochastic
Simulation
Moreira
etal[14]
FLMS
radicCertain
HGA
Mutluetal[5]
FLMS
radicCertain
IGA
Saidi-M
ehrabadetal[16]
FLMS
radicradic
Stochastic
LINGO
Sung
urandYavu
zetal[17]
FLMS
radicCertain
CPLE
XParvin
etal[15]
FLMS
radicradic
Stochastic
Heuris
ticPo
licies
Aryanezhadetal[18]
CMS
Multip
leradic
radicCertain
LINGO
Mahdavietal[19]
CMS
Multip
leCertain
LINGO
Mahdavietal[20]
CMS
Multip
leCertain
LINGO
Bagh
eriand
Bashiri
[32]
CMS
Multip
leradic
Stochastic
LINGO
Niakanetal[22]
CMS
Multip
leradic
radicStochastic
NSG
AII-
MOSA
Liuetal[1]
CMS
Multip
leStochastic
DBF
ALiuetal[23]
CMS
Multip
leradic
Certain
HBF
AAskin
andHuang
[24]
CMS
Multip
leradic
radicStochastic
Greedyheuristic
Norman
etal[25]
CMS
Sing
leradic
radicStochastic
CPLE
XErtayandRu
an[26]
CMS
Sing
leStochastic
DEA
FitzpatrickandAskin
[27]
CMS
Sing
leradic
Stochastic
Balanced
placem
enth
euris
ticCesaniand
Steudel[28]
CMS
Sing
leradic
Certain
Simulation
Suer
andTu
mmaluri[33]
CMS
Sing
leradic
Stochastic
Max
andMaxMin
heuristic
McD
onaldetal[29]
CMS
Sing
leradic
radicCertain
CPLE
XMuralietal[30]
CMS
Multip
leradic
radicCertain
ANN
Egilm
ezetal[31]
CMS
Multip
leradic
Certain
LINGO
6 Mathematical Problems in Engineering
Table 2 Model notations and definitions
Index sets Definitions119888 Index of cells (119888 = 1 2 119862)119901 Index of parts (119901 = 1 2 119875)119895 Index of tasks (119895 = 1 2 119869)119896 Index of workers (119896 = 1 2 119870)119897 Index of skill levels (119897 = 1 2 119871)Parameters Definitions119862 Number of cells119875 Number of parts119869 Number of tasks119870 Number of workers119871 Number of skill levels119879119862119895 Training cost of task 119895119879119888119901119895 Standard processing time of part type 119901 at task 119895 in cell 119888119889119888119901119895 Required throughput of part type 119901 at task 119895 in cell 119888 in one shift119882119896119895 Initial skill level weight of worker k at task 119895119908119897 Weight of skill level 119897119867 Available working time in one shift119881 Maximum permissible training cost120572 Penalty cost of workload imbalance119872 Large value1205871 1205872 Weight factorsVariables Definitions119885119888119896119897119895 1 if worker k with skill level l will be assigned to task j in cell c 0 otherwise119910119888119896119895 1 if worker k will be assigned to task j in cell c 0 otherwise119873119888119896 1 if worker k will be assigned into cell c 0 otherwise119882119871119896 Workload of worker k119882119861119888 Workload of bottleneck worker in cell c
119870
sum119896=1
119910119888119896119895 = 0 for forall119888 119895 satisfying119875
sum119901=1
119879119888119901119895 = 0 (5)
119873119888119896 = 1 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 ge 1 (6)
119873119888119896 = 0 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 = 0 (7)
119862
sum119888=1
119873119888119896 le 1 forall119896 (8)
119871
sum119897=1
119885119888119896119897119895 = 119910119888119896119895 forall119888 119896 119895 (9)
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119885119888119896119897119895 lowast 119879119888119901119895 lowast 119889119888119901119895119908119897
le 119867 forall119888 119896 (10)
119882119871119896 =119862
sum119888=1
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119879119888119901119895 lowast 119885119888119896119897119895 lowast 119889119888119901119895119908119897 lowast 119867
forall119896 (11)
119882119861119888 = max119896isin(12119870)
(119882119871119896 lowast 119873119888119896) forall119888 (12)
119871
sum119897=1
119885119888119896119897119895 lowast 119908119897 ge 119910119888119896119895 lowast119882119896119895 forall119888 119896 119895 (13)
119862
sum119888=1
119870
sum119896=1
119869
sum119895=1
119871
sum119897=1
(119908119897 minus119882119896119895) lowast 119879119862119895 lowast 119885119888119896119897119895 le 119881 (14)
119910119888119896119895 119873119888119896 119885119888119896119897119895 = 0 119900119903 1 forall119888 119896 119897 119895 (15)
The first part of the above objective function is tominimize total skill training cost of the needed workers Themodel set skill level varies according to standard task timeA higher skill level refers to the worker needing less time tofinish the assigned task The cost increases when the workeris trained from a lower skill level to a higher one
The second part of the objective function is to minimizethe penalty cost of workload imbalance ie to maximizeworkload balance of assigned workers in each cell Thepenalty cost forces workload balance by reasonable workerassignment and cross-training 1205871 and 1205872 display the trade-off between training expenditure and workload balance Arelatively lower value of 1205871 and a higher value of 1205872 standfor the situation that training is recommended strongly formore exact workload balance but is accompanied with moreexpenditure Conversely a relatively higher value of 1205871 and a
Mathematical Problems in Engineering 7
lower value of 1205872 stand for the situation that training is notrecommended for less expenditure but is accompanied withless exact workload balance The decision-maker could setthe value of 1205871 and 1205872 according to the recommendation oftraining for skill level enhancement
The third part focuses on minimizing the number ofassigned workers Considering the current economic envi-ronment where labor cost is rapidly increasing this researchconsiders theminimumnumber of workers as the top priorityin the model
Constraints (4) and (5) ensure that all tasks should beallocated to the workers Constraints (6) and (7) guaranteethat one worker can handle more than one task Constraint(8) ensures that one worker could not be assigned to morethan one cell Constraint (9) guarantees that worker assignedto a task with one and only skill level Constraint (10) ensuresthat the customer demand is met Constraint (11) calculatesworkload of each assigned worker Constraint (12) definesworkload of the bottleneck worker in cell Constraint (13)ensures that the skill level of the assigned worker is not lessthan its initial level Constraint (14) ensures that the totalwork training cost does not exceed budget
4 Swarm Intelligence Metaheuristics forWorker Assignment
In this section two classical PSO variants ie GPSO andLPSO and ABC are introduced briefly Next we presentthe STABC with enhanced learning strategy to improvecomputational performanceThis is followed by the designedimplementations of the algorithms for the mathematicalmodel
41 Particle Swarm Optimization Particle swarm opti-mization (PSO) is a stochastic swarm-based metaheuristicinspired by the group behaviors of bird flocking and fishingschooling [11] In PSO a group of particles are employed tocollaboratively explore the problem landscape Each particlehas velocity and position information and moves towardsits historical best position in conjunction with populationbest position found so far Supposing that searching space isD-dimensional the m-th particlersquos velocity and position areupdated as follows
119901V119889119898 = 119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119892119887119890119904119905119889119898 minus 119883119889119898)
(16)
119883119889119898 = 119883119889119898 + 119901V119889119898 (17)
where 1199031 and 1199032 are two positive constriction coefficients1199031198861198991198891198891 and 1199031198861198991198891198892 are two random numbers between [0 1]119883119898 = (1198831119898 1198832119898 119883119863119898) is the position of particle m 119901V119898 =(119901V1119898 119901V2119898 119901V119863119898) is the velocity of particle m 119901119887119890119904119905119898 =(1199011198871198901199041199051119898 1199011198871198901199041199052119898 119901119887119890119904119905119863119898) is the best previous position forparticle m and 119892119887119890119904119905119898 = (1198921198871198901199041199051119898 1198921198871198901199041199052119898 119892119887119890119904119905119863119898) is thebest position discovered by the population so far
Global topology Local topology
Figure 1 Global and local topology structure
Many variants of PSO have been studied since theinception [45 46] A standard version is presented in [32]The standard PSO employs constricted factor 120594 as shown inthe following to guide population search
120594 = 210038161003816100381610038161003816100381610038162 minus 120593 minus radic1205932 minus 4120593
1003816100381610038161003816100381610038161003816 120593 = 1199031 + 1199032 (18)
where 1199031 and 1199032 are set to be constants to ensure the speed ofconvergence [45] With the constriction factor the originalvelocity equation is given as follows
119901V119889119898 = 120594 (119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119871119864119889119898 minus 119883119889119898))
(19)
where LEd represents the previous best information in pop-ulation It is GPSO when a neighbor could be anyone withinthe population otherwise it is LPSO The structures of thetwo patterns are shown in Figure 1The general procedures ofPSO are given as follows
(1) Initialize population size of particle swarm maxi-mum number of iterations and the constants (r1 andr2)
(2) Randomly generate a swarm of particles and initializethe velocity and position of each particle in the searchboundary
(3) Evaluate each particlersquos fitness value(4) Renew particlersquos personal best by comparing current
best information with its historical best information(5) Update the swarm best information using the best
neighborsrsquo information in population(6) Each particle updates its velocity by (19)(7) Each particle updates its position by (17)(8) Go to (3) if the stop criteria are not met otherwise
terminate the iteration
42 Artificial Bee Colony Algorithm Artificial bee colony(ABC) algorithm is inspired by the foraging behaviors in ahoney bee swarm for real-parameter optimization [12] InABC there are three types of bees employed bees onlooker
8 Mathematical Problems in Engineering
bees and scout bees The goal of the whole bees is tocollaboratively find the largest source of nectar The actuallocation of the food source represents a possible solution forthe optimization problems in ABC and the density of nectarcorresponds to a fitness value of solutionThenumber of foodsources represents the swarm size PS
In the iteration each employed bee explores the foodsource using the following
119887V119889119898 = 119909119889119898 + 120601119889119898 (119909119889119898 minus 119909119889119902) 119898 = 119902 (20)
where 119887V119889119898 denotes a candidate food source positionmm= 12 PS 120601119889119898 is a randomly produced value within [-1 1] 119909119889119898refers to the corresponding food source and 119909119889119902 is a randomlyselected food source
Each onlooker bee randomly selects its food sourcem for further refinement with a probability 119901119898 which isdetermined as follows
119901119898 =119891119894119905119899119890119904119904119898
sum119878119904=1 119891119894119905119899119890119904119904119904(21)
where119891119894119905119899119890119904119904119898 is the quality of them-th food source For theminimization problem the 119891119894119905119899119890119904119904119898 can be calculated usingthe following
119891119894119905119899119890119904119904119898 =
1(1 + 119891119898)
if 119891119898 ge 01 + 119886119887119904 (119891119898) if 119891119898 le 0
(22)
where 119891119898 is the m-th objective function value The value ofldquolimitrdquo to abandon the poor food source is suggested to be setto PSlowastD [47] The main steps of ABC are given below
(1) Initialize the number of food sources the limit andthe maximum number of iterations
(2) Randomly generate the positions of food sources inproblem landscape
(3) Evaluate the fitness value of food sources foundcurrently
(4) Each employed bee explores between a randomexem-plar and their own food source using (20)
(5) Apply greedy selection process to select the best PSpositions and record the updated food sources
(6) Calculate the probability of the food sources withwhich onlooker bees are going to follow by (21)
(7) Produce new solutionusing (20) for the onlooker beesdepending on 119901119894
(8) Conduct greedy selection and update food sourceinformation for onlooker bees
(9) Abandon the food sources with poor nectar and letscouts search for new food sources
(10) Terminate if the stop criteria are met otherwise go to(4)
43 Superior Tracking Artificial Bee Colony Algorithm Asa newly proposed algorithm while promising ABC stillsuffers from two weaknesses First the convergence speed isrelatively slow compared tomany existing swarm intelligencealgorithms Second the capability of exploring global optimais still underperforming on many multimodal problems [48]In the original search behavior of ABC only one dimensionof a bee is selected to learn and renew in each round ofinformation updating This search rule may result in the slowconvergence or inferior exploring capability [49] To addressthis issue the STABC is introduced to improve the searchcapability and convergence speed for global optimization
In STABC the employed bees and onlooker bees areupdated in accordance with the following equation
119887V119898 = 119909119898 + 119903119898 (119909119898 minus 119878119873119898) (23)
where 119887V119898 represents the food position of the m-th (m=1 2 PS) food source to be updated 119903119898 refers to arandomly generated D-dimensional vector and SN is the D-dimensional constructed exemplar for tracking in which theelements are either from itself or from the other superiorfood sources randomly chosen by roulette selection andtournament selection
The detailed procedure of constructing SNm is presentedas follows
(1) Initialize a given probability Pr to decide whichexemplar the current bee should chase itself or theother superior neighbors in the population
(2) For each dimension of 119878119873119889119898 (d = 1 toD) a valuewithin[0 1] is randomly generated(3) If the generated value is larger than Pr two food
positions are randomly chosen for comparison andthe d-th dimension of the better one will be learnedotherwise 119878119873119889119898 will be itself
(4) Repeat the above steps till all dimensions of SNm aredetermined
In STABC all elements of an individual will be likely toupdate at each iteration As a result each bee either exploitsthe local optima by learning from itself or explores the globallandscape by chasing the other individuals in the populationThis search strategy accelerates the convergence speeds ofthe population In addition it remains from ABC originalproperties that every individual could be learning exemplarsFigure 2 displays the flow chart of the STABC algorithm
44 Implementation of the SI-Based Optimizers for Cell For-mation In the proposed mathematical model the computa-tional complexity is dependent on the variable size of 119885119888119896119897119895which is equal to 119888 lowast 119896 lowast 119897 lowast 119895 The search dimension ofsolutionZcklj will be too large to optimize using the traditionalmathematical methods Our preliminary experiment indi-cates that it is extremely hard to obtain a suboptimum if thevariables are without proper treatment Meanwhile a feasiblesolution Z would be hard to locate due to the complexityand discontinuity of constraints To address these issues a SI-based metaheuristic is proposed to explore the global optima
Mathematical Problems in Engineering 9
Begin
Initialize food source positions Setting criteria and itc = 1
Fitness value calculation
Evaluate new solution
Greedy SelectionCalculate the probability
of the food source
Determine the chosenfood source by the
onlooker bees
Output
N
Y
itc gt criteria
itc = itc+1
Greedy SelectionRandomly generate a new
position for the abandonedfood sources
Evaluate new solution
itc iteration counter
Trial successfully update record of each food source
Pr a threshold
randi an interger from a uniform discrete distribution
FS the position of the food sources
FV fitness value
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Figure 2 Flowchart of the STABC algorithm
While implementing the swarm-based optimizers for cross-trained worker assignment problem three important issuesshould be considered encoding decoding and constrainshandling
An effective encoding method is developed in this studyThe original 0-1 planning problem is transformed into aninteger programming problem in which the targeting skilllevel and theworker are allocated to each task tomeet the pro-duction requirements For the population initialization them-th individual is represented as 119909119898 = [1199091198981 1199091198982 119909119898119895]j = 1 2 J where J denotes the value of tasks The range ofthe algorithmic representation 1199091198981 is [1 k+l]
In the decoding process the worker and skill levelindices need to be determined through the algorithmicrepresentation A cross-reference matrix is generated here forconverting individual 119909119898 to the indices of worker and skilllevel Details of procedures involved in the decoding processfor 119909119898 are shown in Figure 3
For the constraints handling process the basic penaltyfunctionmethod is adopted [50] Once the objective functionvalue of 119909119898 and the corresponding constraint violation havebeen obtained the penalty value is added to the objectivefunction value of 119909119898
Begin
Y
1 2 hellip K1 1 2 hellip K2 hellip hellip hellip helliphellip hellip hellip hellip hellipL hellip hellip hellip K+L N
Y
Y
N
c = 1 j = 1empty Zcklj
p = 1P
Cross-reference
Inputxmj
Outputindexvalue
kl
Z(cklj) = 1j = j+1
j gt J
c = c+1j =1
c gt C
Output Zcklj
any(Tcpj)gt0
Figure 3 Decoding procedure
5 Computational Experiment
To validate effectiveness and efficiency of the proposedmathematical model and optimizers computational ex-periments are performed in this section Ten problemsare randomly generated based on previous research(can be accessed at httpsdrivegooglecomopenid=0B18FVuMxAffXLW1mRzVLczlyem8) The experiments areimplemented using MATLAB R2012a and the desktop iswith Intel Core i5 CPU 320GHz and 8GB memory
51 Experiment Settings The cross-trained worker assign-ment problem is based on the formed manufacturing cellsin this research that is part and tasks types had beenfixed after cell formation in CMS Ten cell formation prob-lems are selected from previous literature (see Table 3) Asthe problems are generated with different sizes they arenot directly correlated to each other The different typesof problem size can comprehensively evaluate the scalableperformance of the proposed method on this mathematical
10 Mathematical Problems in Engineering
Table 3 Dimension of test problems
Problem No Number ofParts Tasks Cells Workers
P1 [34] 5 5 2 5P2 [35] 7 5 2 5P3 [36] 6 6 2 6P4 [37] 8 9 2 9P5 [38] 10 8 3 8P6 [36] 8 10 3 10P7 [39] 10 10 3 10P8 [35] 12 10 3 10P9 [40] 18 10 3 10P10 [41] 22 11 3 11
Table 4 Pattern of data generation
Parameters Values119879119862119895 lowastDU(500 1000)119879119888119901119895 DU(01 15)119889119888119901119895 DU(50 150)119882119896119895 Randomly generated in set (0 07 08 09 1 11)119908119897 w1=07 w2=08 w3=09 w4=10 w5=11lowastDU(m n) means discrete uniform distribution varying between m and nThe unit of time is minute
model The additional parameters are randomly generatedas shown in Table 4 To allow one-to-one correspondencebetween workers and tasks in extreme situation we assumedthat the number of available workers is equal to the numberof tasks in CMS The available working time of each workerin a shift is calculated as 8 hlowast60mlowast85=408m The trainingbudget in the factory is sufficient Penalty cost of workloadimbalance 120572 is assumed to be 100 With respect to the trade-off between training expenditure and workload balanceldquo1205871=1 1205872=10rdquo stands for the first situation which refers tothe pursuit of more exact workload balance although moretraining cost should be spent while ldquo1205871=10 1205872=1rdquo standsfor the second situation which refers to saving training costalthough workload balance may not be enforced very well
Themaximum number of iterations is set as 20000 whereall the candidate algorithms are found to converge fast Forthe standard PSO the constant120593=41 and the values120594=07298and r1=r2=205 are gathered (Bratton and Kennedy 2007)For the STABC the range of 119903119898 is empirically set as [0149] which could be a time-varying function as well [49]With respect to the threshold probability Pr of STABC themethod introduced in Liang et alrsquos research [51] is adoptedThe population size is set at 30 for all algorithms [47]
52 Experimental Results Each problem is run indepen-dently 20 times with the four algorithms (GPSO LPSO ABCand STABC) The CPU time for each run does not exceed90s In Table 5 119874119865119881119887 119874119865119881119908 and 119874119865119881119886 represent the bestworst and average objective function values (OFV) of theten problems after 20 runs under the two situations (1205871=1
0
25000
50000
75000
100000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=1 2=10
GPSOLPSO
ABCSTABC
Figure 4 119874119865119881119887 results for the case of 1205871=1 1205872=10
1205872=10) and (1205871=10 1205872=1)The best solutions of119874119865119881119887119874119865119881119908and 119874119865119881119886 found by the four algorithms are shown in boldBased on experimental results three measures to evaluate theeffectiveness of STABC algorithm are defined as follows(1) 119861119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119887 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119861119866119866119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119887byGPSO over 119874119865119881119887 by STABC(2) 119882119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119908between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance119882119866119871119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119908 byLPSO over 119874119865119881119908 by STABC(3) 119860119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119886 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119860119866119860119861119862119878119879119860119861119862 means the rising percentage of 119874119865119881119886 byABC over 119874119865119881119886 by STABC
With respect to the abovemeasures the presented STABCis employed as the basis to compare the performance of theinvolved algorithms A positive value indicates that STABCoutperforms the other algorithms on the optimized problem
Table 6 shows the comparison results on the ten problemsunder the two situations (1205871=1 1205872=10) and (1205871=10 1205872=1) Wesee thatmost of119861119866lowast119878119879119860119861119862119882119866lowast119878119879119860119861119862119860119866lowast119878119879119860119861119862 and all averagevalues are positive Thus better results with respect to119874119865119881119887119874119865119881119908 and 119874119865119881119886 can be attained by STABC compared toGPSO LPSO and ABC under both situations (1205871=1 1205872=10)and (1205871=10 1205872=1)
Figures 4 and 5 compare the 119874119865119881119887obtained by GPSOLPSO ABC and STABC (see Table 5)They demonstrate thatthe best solutions of STABC are better than the others Forthe relatively simple small-size problems such as problems1 2 and 3 most of the algorithms can easily identify thebest results With the increase of problem size STABCoutperforms the other algorithms on the relatively large-sizeproblems The improvement of STBACrsquos search capabilitycan be attributed to two properties (1) each individualrsquoslearning speed for exploration is improved by learning fromother bees in all dimensions and (2) the individualrsquos learningsources for exploitation are enriched by learning fromboth itshistorical information and the superior individualsThenovelstrategies can significantly enhance the global exploration
Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
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6 Mathematical Problems in Engineering
Table 2 Model notations and definitions
Index sets Definitions119888 Index of cells (119888 = 1 2 119862)119901 Index of parts (119901 = 1 2 119875)119895 Index of tasks (119895 = 1 2 119869)119896 Index of workers (119896 = 1 2 119870)119897 Index of skill levels (119897 = 1 2 119871)Parameters Definitions119862 Number of cells119875 Number of parts119869 Number of tasks119870 Number of workers119871 Number of skill levels119879119862119895 Training cost of task 119895119879119888119901119895 Standard processing time of part type 119901 at task 119895 in cell 119888119889119888119901119895 Required throughput of part type 119901 at task 119895 in cell 119888 in one shift119882119896119895 Initial skill level weight of worker k at task 119895119908119897 Weight of skill level 119897119867 Available working time in one shift119881 Maximum permissible training cost120572 Penalty cost of workload imbalance119872 Large value1205871 1205872 Weight factorsVariables Definitions119885119888119896119897119895 1 if worker k with skill level l will be assigned to task j in cell c 0 otherwise119910119888119896119895 1 if worker k will be assigned to task j in cell c 0 otherwise119873119888119896 1 if worker k will be assigned into cell c 0 otherwise119882119871119896 Workload of worker k119882119861119888 Workload of bottleneck worker in cell c
119870
sum119896=1
119910119888119896119895 = 0 for forall119888 119895 satisfying119875
sum119901=1
119879119888119901119895 = 0 (5)
119873119888119896 = 1 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 ge 1 (6)
119873119888119896 = 0 for forall119888 119896 satisfying119869
sum119895=1
119910119888119896119895 = 0 (7)
119862
sum119888=1
119873119888119896 le 1 forall119896 (8)
119871
sum119897=1
119885119888119896119897119895 = 119910119888119896119895 forall119888 119896 119895 (9)
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119885119888119896119897119895 lowast 119879119888119901119895 lowast 119889119888119901119895119908119897
le 119867 forall119888 119896 (10)
119882119871119896 =119862
sum119888=1
119869
sum119895=1
119871
sum119897=1
119875
sum119901=1
119879119888119901119895 lowast 119885119888119896119897119895 lowast 119889119888119901119895119908119897 lowast 119867
forall119896 (11)
119882119861119888 = max119896isin(12119870)
(119882119871119896 lowast 119873119888119896) forall119888 (12)
119871
sum119897=1
119885119888119896119897119895 lowast 119908119897 ge 119910119888119896119895 lowast119882119896119895 forall119888 119896 119895 (13)
119862
sum119888=1
119870
sum119896=1
119869
sum119895=1
119871
sum119897=1
(119908119897 minus119882119896119895) lowast 119879119862119895 lowast 119885119888119896119897119895 le 119881 (14)
119910119888119896119895 119873119888119896 119885119888119896119897119895 = 0 119900119903 1 forall119888 119896 119897 119895 (15)
The first part of the above objective function is tominimize total skill training cost of the needed workers Themodel set skill level varies according to standard task timeA higher skill level refers to the worker needing less time tofinish the assigned task The cost increases when the workeris trained from a lower skill level to a higher one
The second part of the objective function is to minimizethe penalty cost of workload imbalance ie to maximizeworkload balance of assigned workers in each cell Thepenalty cost forces workload balance by reasonable workerassignment and cross-training 1205871 and 1205872 display the trade-off between training expenditure and workload balance Arelatively lower value of 1205871 and a higher value of 1205872 standfor the situation that training is recommended strongly formore exact workload balance but is accompanied with moreexpenditure Conversely a relatively higher value of 1205871 and a
Mathematical Problems in Engineering 7
lower value of 1205872 stand for the situation that training is notrecommended for less expenditure but is accompanied withless exact workload balance The decision-maker could setthe value of 1205871 and 1205872 according to the recommendation oftraining for skill level enhancement
The third part focuses on minimizing the number ofassigned workers Considering the current economic envi-ronment where labor cost is rapidly increasing this researchconsiders theminimumnumber of workers as the top priorityin the model
Constraints (4) and (5) ensure that all tasks should beallocated to the workers Constraints (6) and (7) guaranteethat one worker can handle more than one task Constraint(8) ensures that one worker could not be assigned to morethan one cell Constraint (9) guarantees that worker assignedto a task with one and only skill level Constraint (10) ensuresthat the customer demand is met Constraint (11) calculatesworkload of each assigned worker Constraint (12) definesworkload of the bottleneck worker in cell Constraint (13)ensures that the skill level of the assigned worker is not lessthan its initial level Constraint (14) ensures that the totalwork training cost does not exceed budget
4 Swarm Intelligence Metaheuristics forWorker Assignment
In this section two classical PSO variants ie GPSO andLPSO and ABC are introduced briefly Next we presentthe STABC with enhanced learning strategy to improvecomputational performanceThis is followed by the designedimplementations of the algorithms for the mathematicalmodel
41 Particle Swarm Optimization Particle swarm opti-mization (PSO) is a stochastic swarm-based metaheuristicinspired by the group behaviors of bird flocking and fishingschooling [11] In PSO a group of particles are employed tocollaboratively explore the problem landscape Each particlehas velocity and position information and moves towardsits historical best position in conjunction with populationbest position found so far Supposing that searching space isD-dimensional the m-th particlersquos velocity and position areupdated as follows
119901V119889119898 = 119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119892119887119890119904119905119889119898 minus 119883119889119898)
(16)
119883119889119898 = 119883119889119898 + 119901V119889119898 (17)
where 1199031 and 1199032 are two positive constriction coefficients1199031198861198991198891198891 and 1199031198861198991198891198892 are two random numbers between [0 1]119883119898 = (1198831119898 1198832119898 119883119863119898) is the position of particle m 119901V119898 =(119901V1119898 119901V2119898 119901V119863119898) is the velocity of particle m 119901119887119890119904119905119898 =(1199011198871198901199041199051119898 1199011198871198901199041199052119898 119901119887119890119904119905119863119898) is the best previous position forparticle m and 119892119887119890119904119905119898 = (1198921198871198901199041199051119898 1198921198871198901199041199052119898 119892119887119890119904119905119863119898) is thebest position discovered by the population so far
Global topology Local topology
Figure 1 Global and local topology structure
Many variants of PSO have been studied since theinception [45 46] A standard version is presented in [32]The standard PSO employs constricted factor 120594 as shown inthe following to guide population search
120594 = 210038161003816100381610038161003816100381610038162 minus 120593 minus radic1205932 minus 4120593
1003816100381610038161003816100381610038161003816 120593 = 1199031 + 1199032 (18)
where 1199031 and 1199032 are set to be constants to ensure the speed ofconvergence [45] With the constriction factor the originalvelocity equation is given as follows
119901V119889119898 = 120594 (119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119871119864119889119898 minus 119883119889119898))
(19)
where LEd represents the previous best information in pop-ulation It is GPSO when a neighbor could be anyone withinthe population otherwise it is LPSO The structures of thetwo patterns are shown in Figure 1The general procedures ofPSO are given as follows
(1) Initialize population size of particle swarm maxi-mum number of iterations and the constants (r1 andr2)
(2) Randomly generate a swarm of particles and initializethe velocity and position of each particle in the searchboundary
(3) Evaluate each particlersquos fitness value(4) Renew particlersquos personal best by comparing current
best information with its historical best information(5) Update the swarm best information using the best
neighborsrsquo information in population(6) Each particle updates its velocity by (19)(7) Each particle updates its position by (17)(8) Go to (3) if the stop criteria are not met otherwise
terminate the iteration
42 Artificial Bee Colony Algorithm Artificial bee colony(ABC) algorithm is inspired by the foraging behaviors in ahoney bee swarm for real-parameter optimization [12] InABC there are three types of bees employed bees onlooker
8 Mathematical Problems in Engineering
bees and scout bees The goal of the whole bees is tocollaboratively find the largest source of nectar The actuallocation of the food source represents a possible solution forthe optimization problems in ABC and the density of nectarcorresponds to a fitness value of solutionThenumber of foodsources represents the swarm size PS
In the iteration each employed bee explores the foodsource using the following
119887V119889119898 = 119909119889119898 + 120601119889119898 (119909119889119898 minus 119909119889119902) 119898 = 119902 (20)
where 119887V119889119898 denotes a candidate food source positionmm= 12 PS 120601119889119898 is a randomly produced value within [-1 1] 119909119889119898refers to the corresponding food source and 119909119889119902 is a randomlyselected food source
Each onlooker bee randomly selects its food sourcem for further refinement with a probability 119901119898 which isdetermined as follows
119901119898 =119891119894119905119899119890119904119904119898
sum119878119904=1 119891119894119905119899119890119904119904119904(21)
where119891119894119905119899119890119904119904119898 is the quality of them-th food source For theminimization problem the 119891119894119905119899119890119904119904119898 can be calculated usingthe following
119891119894119905119899119890119904119904119898 =
1(1 + 119891119898)
if 119891119898 ge 01 + 119886119887119904 (119891119898) if 119891119898 le 0
(22)
where 119891119898 is the m-th objective function value The value ofldquolimitrdquo to abandon the poor food source is suggested to be setto PSlowastD [47] The main steps of ABC are given below
(1) Initialize the number of food sources the limit andthe maximum number of iterations
(2) Randomly generate the positions of food sources inproblem landscape
(3) Evaluate the fitness value of food sources foundcurrently
(4) Each employed bee explores between a randomexem-plar and their own food source using (20)
(5) Apply greedy selection process to select the best PSpositions and record the updated food sources
(6) Calculate the probability of the food sources withwhich onlooker bees are going to follow by (21)
(7) Produce new solutionusing (20) for the onlooker beesdepending on 119901119894
(8) Conduct greedy selection and update food sourceinformation for onlooker bees
(9) Abandon the food sources with poor nectar and letscouts search for new food sources
(10) Terminate if the stop criteria are met otherwise go to(4)
43 Superior Tracking Artificial Bee Colony Algorithm Asa newly proposed algorithm while promising ABC stillsuffers from two weaknesses First the convergence speed isrelatively slow compared tomany existing swarm intelligencealgorithms Second the capability of exploring global optimais still underperforming on many multimodal problems [48]In the original search behavior of ABC only one dimensionof a bee is selected to learn and renew in each round ofinformation updating This search rule may result in the slowconvergence or inferior exploring capability [49] To addressthis issue the STABC is introduced to improve the searchcapability and convergence speed for global optimization
In STABC the employed bees and onlooker bees areupdated in accordance with the following equation
119887V119898 = 119909119898 + 119903119898 (119909119898 minus 119878119873119898) (23)
where 119887V119898 represents the food position of the m-th (m=1 2 PS) food source to be updated 119903119898 refers to arandomly generated D-dimensional vector and SN is the D-dimensional constructed exemplar for tracking in which theelements are either from itself or from the other superiorfood sources randomly chosen by roulette selection andtournament selection
The detailed procedure of constructing SNm is presentedas follows
(1) Initialize a given probability Pr to decide whichexemplar the current bee should chase itself or theother superior neighbors in the population
(2) For each dimension of 119878119873119889119898 (d = 1 toD) a valuewithin[0 1] is randomly generated(3) If the generated value is larger than Pr two food
positions are randomly chosen for comparison andthe d-th dimension of the better one will be learnedotherwise 119878119873119889119898 will be itself
(4) Repeat the above steps till all dimensions of SNm aredetermined
In STABC all elements of an individual will be likely toupdate at each iteration As a result each bee either exploitsthe local optima by learning from itself or explores the globallandscape by chasing the other individuals in the populationThis search strategy accelerates the convergence speeds ofthe population In addition it remains from ABC originalproperties that every individual could be learning exemplarsFigure 2 displays the flow chart of the STABC algorithm
44 Implementation of the SI-Based Optimizers for Cell For-mation In the proposed mathematical model the computa-tional complexity is dependent on the variable size of 119885119888119896119897119895which is equal to 119888 lowast 119896 lowast 119897 lowast 119895 The search dimension ofsolutionZcklj will be too large to optimize using the traditionalmathematical methods Our preliminary experiment indi-cates that it is extremely hard to obtain a suboptimum if thevariables are without proper treatment Meanwhile a feasiblesolution Z would be hard to locate due to the complexityand discontinuity of constraints To address these issues a SI-based metaheuristic is proposed to explore the global optima
Mathematical Problems in Engineering 9
Begin
Initialize food source positions Setting criteria and itc = 1
Fitness value calculation
Evaluate new solution
Greedy SelectionCalculate the probability
of the food source
Determine the chosenfood source by the
onlooker bees
Output
N
Y
itc gt criteria
itc = itc+1
Greedy SelectionRandomly generate a new
position for the abandonedfood sources
Evaluate new solution
itc iteration counter
Trial successfully update record of each food source
Pr a threshold
randi an interger from a uniform discrete distribution
FS the position of the food sources
FV fitness value
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Figure 2 Flowchart of the STABC algorithm
While implementing the swarm-based optimizers for cross-trained worker assignment problem three important issuesshould be considered encoding decoding and constrainshandling
An effective encoding method is developed in this studyThe original 0-1 planning problem is transformed into aninteger programming problem in which the targeting skilllevel and theworker are allocated to each task tomeet the pro-duction requirements For the population initialization them-th individual is represented as 119909119898 = [1199091198981 1199091198982 119909119898119895]j = 1 2 J where J denotes the value of tasks The range ofthe algorithmic representation 1199091198981 is [1 k+l]
In the decoding process the worker and skill levelindices need to be determined through the algorithmicrepresentation A cross-reference matrix is generated here forconverting individual 119909119898 to the indices of worker and skilllevel Details of procedures involved in the decoding processfor 119909119898 are shown in Figure 3
For the constraints handling process the basic penaltyfunctionmethod is adopted [50] Once the objective functionvalue of 119909119898 and the corresponding constraint violation havebeen obtained the penalty value is added to the objectivefunction value of 119909119898
Begin
Y
1 2 hellip K1 1 2 hellip K2 hellip hellip hellip helliphellip hellip hellip hellip hellipL hellip hellip hellip K+L N
Y
Y
N
c = 1 j = 1empty Zcklj
p = 1P
Cross-reference
Inputxmj
Outputindexvalue
kl
Z(cklj) = 1j = j+1
j gt J
c = c+1j =1
c gt C
Output Zcklj
any(Tcpj)gt0
Figure 3 Decoding procedure
5 Computational Experiment
To validate effectiveness and efficiency of the proposedmathematical model and optimizers computational ex-periments are performed in this section Ten problemsare randomly generated based on previous research(can be accessed at httpsdrivegooglecomopenid=0B18FVuMxAffXLW1mRzVLczlyem8) The experiments areimplemented using MATLAB R2012a and the desktop iswith Intel Core i5 CPU 320GHz and 8GB memory
51 Experiment Settings The cross-trained worker assign-ment problem is based on the formed manufacturing cellsin this research that is part and tasks types had beenfixed after cell formation in CMS Ten cell formation prob-lems are selected from previous literature (see Table 3) Asthe problems are generated with different sizes they arenot directly correlated to each other The different typesof problem size can comprehensively evaluate the scalableperformance of the proposed method on this mathematical
10 Mathematical Problems in Engineering
Table 3 Dimension of test problems
Problem No Number ofParts Tasks Cells Workers
P1 [34] 5 5 2 5P2 [35] 7 5 2 5P3 [36] 6 6 2 6P4 [37] 8 9 2 9P5 [38] 10 8 3 8P6 [36] 8 10 3 10P7 [39] 10 10 3 10P8 [35] 12 10 3 10P9 [40] 18 10 3 10P10 [41] 22 11 3 11
Table 4 Pattern of data generation
Parameters Values119879119862119895 lowastDU(500 1000)119879119888119901119895 DU(01 15)119889119888119901119895 DU(50 150)119882119896119895 Randomly generated in set (0 07 08 09 1 11)119908119897 w1=07 w2=08 w3=09 w4=10 w5=11lowastDU(m n) means discrete uniform distribution varying between m and nThe unit of time is minute
model The additional parameters are randomly generatedas shown in Table 4 To allow one-to-one correspondencebetween workers and tasks in extreme situation we assumedthat the number of available workers is equal to the numberof tasks in CMS The available working time of each workerin a shift is calculated as 8 hlowast60mlowast85=408m The trainingbudget in the factory is sufficient Penalty cost of workloadimbalance 120572 is assumed to be 100 With respect to the trade-off between training expenditure and workload balanceldquo1205871=1 1205872=10rdquo stands for the first situation which refers tothe pursuit of more exact workload balance although moretraining cost should be spent while ldquo1205871=10 1205872=1rdquo standsfor the second situation which refers to saving training costalthough workload balance may not be enforced very well
Themaximum number of iterations is set as 20000 whereall the candidate algorithms are found to converge fast Forthe standard PSO the constant120593=41 and the values120594=07298and r1=r2=205 are gathered (Bratton and Kennedy 2007)For the STABC the range of 119903119898 is empirically set as [0149] which could be a time-varying function as well [49]With respect to the threshold probability Pr of STABC themethod introduced in Liang et alrsquos research [51] is adoptedThe population size is set at 30 for all algorithms [47]
52 Experimental Results Each problem is run indepen-dently 20 times with the four algorithms (GPSO LPSO ABCand STABC) The CPU time for each run does not exceed90s In Table 5 119874119865119881119887 119874119865119881119908 and 119874119865119881119886 represent the bestworst and average objective function values (OFV) of theten problems after 20 runs under the two situations (1205871=1
0
25000
50000
75000
100000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=1 2=10
GPSOLPSO
ABCSTABC
Figure 4 119874119865119881119887 results for the case of 1205871=1 1205872=10
1205872=10) and (1205871=10 1205872=1)The best solutions of119874119865119881119887119874119865119881119908and 119874119865119881119886 found by the four algorithms are shown in boldBased on experimental results three measures to evaluate theeffectiveness of STABC algorithm are defined as follows(1) 119861119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119887 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119861119866119866119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119887byGPSO over 119874119865119881119887 by STABC(2) 119882119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119908between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance119882119866119871119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119908 byLPSO over 119874119865119881119908 by STABC(3) 119860119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119886 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119860119866119860119861119862119878119879119860119861119862 means the rising percentage of 119874119865119881119886 byABC over 119874119865119881119886 by STABC
With respect to the abovemeasures the presented STABCis employed as the basis to compare the performance of theinvolved algorithms A positive value indicates that STABCoutperforms the other algorithms on the optimized problem
Table 6 shows the comparison results on the ten problemsunder the two situations (1205871=1 1205872=10) and (1205871=10 1205872=1) Wesee thatmost of119861119866lowast119878119879119860119861119862119882119866lowast119878119879119860119861119862119860119866lowast119878119879119860119861119862 and all averagevalues are positive Thus better results with respect to119874119865119881119887119874119865119881119908 and 119874119865119881119886 can be attained by STABC compared toGPSO LPSO and ABC under both situations (1205871=1 1205872=10)and (1205871=10 1205872=1)
Figures 4 and 5 compare the 119874119865119881119887obtained by GPSOLPSO ABC and STABC (see Table 5)They demonstrate thatthe best solutions of STABC are better than the others Forthe relatively simple small-size problems such as problems1 2 and 3 most of the algorithms can easily identify thebest results With the increase of problem size STABCoutperforms the other algorithms on the relatively large-sizeproblems The improvement of STBACrsquos search capabilitycan be attributed to two properties (1) each individualrsquoslearning speed for exploration is improved by learning fromother bees in all dimensions and (2) the individualrsquos learningsources for exploitation are enriched by learning fromboth itshistorical information and the superior individualsThenovelstrategies can significantly enhance the global exploration
Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
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Mathematical Problems in Engineering 7
lower value of 1205872 stand for the situation that training is notrecommended for less expenditure but is accompanied withless exact workload balance The decision-maker could setthe value of 1205871 and 1205872 according to the recommendation oftraining for skill level enhancement
The third part focuses on minimizing the number ofassigned workers Considering the current economic envi-ronment where labor cost is rapidly increasing this researchconsiders theminimumnumber of workers as the top priorityin the model
Constraints (4) and (5) ensure that all tasks should beallocated to the workers Constraints (6) and (7) guaranteethat one worker can handle more than one task Constraint(8) ensures that one worker could not be assigned to morethan one cell Constraint (9) guarantees that worker assignedto a task with one and only skill level Constraint (10) ensuresthat the customer demand is met Constraint (11) calculatesworkload of each assigned worker Constraint (12) definesworkload of the bottleneck worker in cell Constraint (13)ensures that the skill level of the assigned worker is not lessthan its initial level Constraint (14) ensures that the totalwork training cost does not exceed budget
4 Swarm Intelligence Metaheuristics forWorker Assignment
In this section two classical PSO variants ie GPSO andLPSO and ABC are introduced briefly Next we presentthe STABC with enhanced learning strategy to improvecomputational performanceThis is followed by the designedimplementations of the algorithms for the mathematicalmodel
41 Particle Swarm Optimization Particle swarm opti-mization (PSO) is a stochastic swarm-based metaheuristicinspired by the group behaviors of bird flocking and fishingschooling [11] In PSO a group of particles are employed tocollaboratively explore the problem landscape Each particlehas velocity and position information and moves towardsits historical best position in conjunction with populationbest position found so far Supposing that searching space isD-dimensional the m-th particlersquos velocity and position areupdated as follows
119901V119889119898 = 119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119892119887119890119904119905119889119898 minus 119883119889119898)
(16)
119883119889119898 = 119883119889119898 + 119901V119889119898 (17)
where 1199031 and 1199032 are two positive constriction coefficients1199031198861198991198891198891 and 1199031198861198991198891198892 are two random numbers between [0 1]119883119898 = (1198831119898 1198832119898 119883119863119898) is the position of particle m 119901V119898 =(119901V1119898 119901V2119898 119901V119863119898) is the velocity of particle m 119901119887119890119904119905119898 =(1199011198871198901199041199051119898 1199011198871198901199041199052119898 119901119887119890119904119905119863119898) is the best previous position forparticle m and 119892119887119890119904119905119898 = (1198921198871198901199041199051119898 1198921198871198901199041199052119898 119892119887119890119904119905119863119898) is thebest position discovered by the population so far
Global topology Local topology
Figure 1 Global and local topology structure
Many variants of PSO have been studied since theinception [45 46] A standard version is presented in [32]The standard PSO employs constricted factor 120594 as shown inthe following to guide population search
120594 = 210038161003816100381610038161003816100381610038162 minus 120593 minus radic1205932 minus 4120593
1003816100381610038161003816100381610038161003816 120593 = 1199031 + 1199032 (18)
where 1199031 and 1199032 are set to be constants to ensure the speed ofconvergence [45] With the constriction factor the originalvelocity equation is given as follows
119901V119889119898 = 120594 (119901V119889119898 + 1199031 lowast 1199031198861198991198891198891119898 lowast (119901119887119890119904119905119889119898 minus 119883119889119898) + 1199032lowast 1199031198861198991198891198892119898 lowast (119871119864119889119898 minus 119883119889119898))
(19)
where LEd represents the previous best information in pop-ulation It is GPSO when a neighbor could be anyone withinthe population otherwise it is LPSO The structures of thetwo patterns are shown in Figure 1The general procedures ofPSO are given as follows
(1) Initialize population size of particle swarm maxi-mum number of iterations and the constants (r1 andr2)
(2) Randomly generate a swarm of particles and initializethe velocity and position of each particle in the searchboundary
(3) Evaluate each particlersquos fitness value(4) Renew particlersquos personal best by comparing current
best information with its historical best information(5) Update the swarm best information using the best
neighborsrsquo information in population(6) Each particle updates its velocity by (19)(7) Each particle updates its position by (17)(8) Go to (3) if the stop criteria are not met otherwise
terminate the iteration
42 Artificial Bee Colony Algorithm Artificial bee colony(ABC) algorithm is inspired by the foraging behaviors in ahoney bee swarm for real-parameter optimization [12] InABC there are three types of bees employed bees onlooker
8 Mathematical Problems in Engineering
bees and scout bees The goal of the whole bees is tocollaboratively find the largest source of nectar The actuallocation of the food source represents a possible solution forthe optimization problems in ABC and the density of nectarcorresponds to a fitness value of solutionThenumber of foodsources represents the swarm size PS
In the iteration each employed bee explores the foodsource using the following
119887V119889119898 = 119909119889119898 + 120601119889119898 (119909119889119898 minus 119909119889119902) 119898 = 119902 (20)
where 119887V119889119898 denotes a candidate food source positionmm= 12 PS 120601119889119898 is a randomly produced value within [-1 1] 119909119889119898refers to the corresponding food source and 119909119889119902 is a randomlyselected food source
Each onlooker bee randomly selects its food sourcem for further refinement with a probability 119901119898 which isdetermined as follows
119901119898 =119891119894119905119899119890119904119904119898
sum119878119904=1 119891119894119905119899119890119904119904119904(21)
where119891119894119905119899119890119904119904119898 is the quality of them-th food source For theminimization problem the 119891119894119905119899119890119904119904119898 can be calculated usingthe following
119891119894119905119899119890119904119904119898 =
1(1 + 119891119898)
if 119891119898 ge 01 + 119886119887119904 (119891119898) if 119891119898 le 0
(22)
where 119891119898 is the m-th objective function value The value ofldquolimitrdquo to abandon the poor food source is suggested to be setto PSlowastD [47] The main steps of ABC are given below
(1) Initialize the number of food sources the limit andthe maximum number of iterations
(2) Randomly generate the positions of food sources inproblem landscape
(3) Evaluate the fitness value of food sources foundcurrently
(4) Each employed bee explores between a randomexem-plar and their own food source using (20)
(5) Apply greedy selection process to select the best PSpositions and record the updated food sources
(6) Calculate the probability of the food sources withwhich onlooker bees are going to follow by (21)
(7) Produce new solutionusing (20) for the onlooker beesdepending on 119901119894
(8) Conduct greedy selection and update food sourceinformation for onlooker bees
(9) Abandon the food sources with poor nectar and letscouts search for new food sources
(10) Terminate if the stop criteria are met otherwise go to(4)
43 Superior Tracking Artificial Bee Colony Algorithm Asa newly proposed algorithm while promising ABC stillsuffers from two weaknesses First the convergence speed isrelatively slow compared tomany existing swarm intelligencealgorithms Second the capability of exploring global optimais still underperforming on many multimodal problems [48]In the original search behavior of ABC only one dimensionof a bee is selected to learn and renew in each round ofinformation updating This search rule may result in the slowconvergence or inferior exploring capability [49] To addressthis issue the STABC is introduced to improve the searchcapability and convergence speed for global optimization
In STABC the employed bees and onlooker bees areupdated in accordance with the following equation
119887V119898 = 119909119898 + 119903119898 (119909119898 minus 119878119873119898) (23)
where 119887V119898 represents the food position of the m-th (m=1 2 PS) food source to be updated 119903119898 refers to arandomly generated D-dimensional vector and SN is the D-dimensional constructed exemplar for tracking in which theelements are either from itself or from the other superiorfood sources randomly chosen by roulette selection andtournament selection
The detailed procedure of constructing SNm is presentedas follows
(1) Initialize a given probability Pr to decide whichexemplar the current bee should chase itself or theother superior neighbors in the population
(2) For each dimension of 119878119873119889119898 (d = 1 toD) a valuewithin[0 1] is randomly generated(3) If the generated value is larger than Pr two food
positions are randomly chosen for comparison andthe d-th dimension of the better one will be learnedotherwise 119878119873119889119898 will be itself
(4) Repeat the above steps till all dimensions of SNm aredetermined
In STABC all elements of an individual will be likely toupdate at each iteration As a result each bee either exploitsthe local optima by learning from itself or explores the globallandscape by chasing the other individuals in the populationThis search strategy accelerates the convergence speeds ofthe population In addition it remains from ABC originalproperties that every individual could be learning exemplarsFigure 2 displays the flow chart of the STABC algorithm
44 Implementation of the SI-Based Optimizers for Cell For-mation In the proposed mathematical model the computa-tional complexity is dependent on the variable size of 119885119888119896119897119895which is equal to 119888 lowast 119896 lowast 119897 lowast 119895 The search dimension ofsolutionZcklj will be too large to optimize using the traditionalmathematical methods Our preliminary experiment indi-cates that it is extremely hard to obtain a suboptimum if thevariables are without proper treatment Meanwhile a feasiblesolution Z would be hard to locate due to the complexityand discontinuity of constraints To address these issues a SI-based metaheuristic is proposed to explore the global optima
Mathematical Problems in Engineering 9
Begin
Initialize food source positions Setting criteria and itc = 1
Fitness value calculation
Evaluate new solution
Greedy SelectionCalculate the probability
of the food source
Determine the chosenfood source by the
onlooker bees
Output
N
Y
itc gt criteria
itc = itc+1
Greedy SelectionRandomly generate a new
position for the abandonedfood sources
Evaluate new solution
itc iteration counter
Trial successfully update record of each food source
Pr a threshold
randi an interger from a uniform discrete distribution
FS the position of the food sources
FV fitness value
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Figure 2 Flowchart of the STABC algorithm
While implementing the swarm-based optimizers for cross-trained worker assignment problem three important issuesshould be considered encoding decoding and constrainshandling
An effective encoding method is developed in this studyThe original 0-1 planning problem is transformed into aninteger programming problem in which the targeting skilllevel and theworker are allocated to each task tomeet the pro-duction requirements For the population initialization them-th individual is represented as 119909119898 = [1199091198981 1199091198982 119909119898119895]j = 1 2 J where J denotes the value of tasks The range ofthe algorithmic representation 1199091198981 is [1 k+l]
In the decoding process the worker and skill levelindices need to be determined through the algorithmicrepresentation A cross-reference matrix is generated here forconverting individual 119909119898 to the indices of worker and skilllevel Details of procedures involved in the decoding processfor 119909119898 are shown in Figure 3
For the constraints handling process the basic penaltyfunctionmethod is adopted [50] Once the objective functionvalue of 119909119898 and the corresponding constraint violation havebeen obtained the penalty value is added to the objectivefunction value of 119909119898
Begin
Y
1 2 hellip K1 1 2 hellip K2 hellip hellip hellip helliphellip hellip hellip hellip hellipL hellip hellip hellip K+L N
Y
Y
N
c = 1 j = 1empty Zcklj
p = 1P
Cross-reference
Inputxmj
Outputindexvalue
kl
Z(cklj) = 1j = j+1
j gt J
c = c+1j =1
c gt C
Output Zcklj
any(Tcpj)gt0
Figure 3 Decoding procedure
5 Computational Experiment
To validate effectiveness and efficiency of the proposedmathematical model and optimizers computational ex-periments are performed in this section Ten problemsare randomly generated based on previous research(can be accessed at httpsdrivegooglecomopenid=0B18FVuMxAffXLW1mRzVLczlyem8) The experiments areimplemented using MATLAB R2012a and the desktop iswith Intel Core i5 CPU 320GHz and 8GB memory
51 Experiment Settings The cross-trained worker assign-ment problem is based on the formed manufacturing cellsin this research that is part and tasks types had beenfixed after cell formation in CMS Ten cell formation prob-lems are selected from previous literature (see Table 3) Asthe problems are generated with different sizes they arenot directly correlated to each other The different typesof problem size can comprehensively evaluate the scalableperformance of the proposed method on this mathematical
10 Mathematical Problems in Engineering
Table 3 Dimension of test problems
Problem No Number ofParts Tasks Cells Workers
P1 [34] 5 5 2 5P2 [35] 7 5 2 5P3 [36] 6 6 2 6P4 [37] 8 9 2 9P5 [38] 10 8 3 8P6 [36] 8 10 3 10P7 [39] 10 10 3 10P8 [35] 12 10 3 10P9 [40] 18 10 3 10P10 [41] 22 11 3 11
Table 4 Pattern of data generation
Parameters Values119879119862119895 lowastDU(500 1000)119879119888119901119895 DU(01 15)119889119888119901119895 DU(50 150)119882119896119895 Randomly generated in set (0 07 08 09 1 11)119908119897 w1=07 w2=08 w3=09 w4=10 w5=11lowastDU(m n) means discrete uniform distribution varying between m and nThe unit of time is minute
model The additional parameters are randomly generatedas shown in Table 4 To allow one-to-one correspondencebetween workers and tasks in extreme situation we assumedthat the number of available workers is equal to the numberof tasks in CMS The available working time of each workerin a shift is calculated as 8 hlowast60mlowast85=408m The trainingbudget in the factory is sufficient Penalty cost of workloadimbalance 120572 is assumed to be 100 With respect to the trade-off between training expenditure and workload balanceldquo1205871=1 1205872=10rdquo stands for the first situation which refers tothe pursuit of more exact workload balance although moretraining cost should be spent while ldquo1205871=10 1205872=1rdquo standsfor the second situation which refers to saving training costalthough workload balance may not be enforced very well
Themaximum number of iterations is set as 20000 whereall the candidate algorithms are found to converge fast Forthe standard PSO the constant120593=41 and the values120594=07298and r1=r2=205 are gathered (Bratton and Kennedy 2007)For the STABC the range of 119903119898 is empirically set as [0149] which could be a time-varying function as well [49]With respect to the threshold probability Pr of STABC themethod introduced in Liang et alrsquos research [51] is adoptedThe population size is set at 30 for all algorithms [47]
52 Experimental Results Each problem is run indepen-dently 20 times with the four algorithms (GPSO LPSO ABCand STABC) The CPU time for each run does not exceed90s In Table 5 119874119865119881119887 119874119865119881119908 and 119874119865119881119886 represent the bestworst and average objective function values (OFV) of theten problems after 20 runs under the two situations (1205871=1
0
25000
50000
75000
100000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=1 2=10
GPSOLPSO
ABCSTABC
Figure 4 119874119865119881119887 results for the case of 1205871=1 1205872=10
1205872=10) and (1205871=10 1205872=1)The best solutions of119874119865119881119887119874119865119881119908and 119874119865119881119886 found by the four algorithms are shown in boldBased on experimental results three measures to evaluate theeffectiveness of STABC algorithm are defined as follows(1) 119861119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119887 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119861119866119866119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119887byGPSO over 119874119865119881119887 by STABC(2) 119882119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119908between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance119882119866119871119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119908 byLPSO over 119874119865119881119908 by STABC(3) 119860119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119886 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119860119866119860119861119862119878119879119860119861119862 means the rising percentage of 119874119865119881119886 byABC over 119874119865119881119886 by STABC
With respect to the abovemeasures the presented STABCis employed as the basis to compare the performance of theinvolved algorithms A positive value indicates that STABCoutperforms the other algorithms on the optimized problem
Table 6 shows the comparison results on the ten problemsunder the two situations (1205871=1 1205872=10) and (1205871=10 1205872=1) Wesee thatmost of119861119866lowast119878119879119860119861119862119882119866lowast119878119879119860119861119862119860119866lowast119878119879119860119861119862 and all averagevalues are positive Thus better results with respect to119874119865119881119887119874119865119881119908 and 119874119865119881119886 can be attained by STABC compared toGPSO LPSO and ABC under both situations (1205871=1 1205872=10)and (1205871=10 1205872=1)
Figures 4 and 5 compare the 119874119865119881119887obtained by GPSOLPSO ABC and STABC (see Table 5)They demonstrate thatthe best solutions of STABC are better than the others Forthe relatively simple small-size problems such as problems1 2 and 3 most of the algorithms can easily identify thebest results With the increase of problem size STABCoutperforms the other algorithms on the relatively large-sizeproblems The improvement of STBACrsquos search capabilitycan be attributed to two properties (1) each individualrsquoslearning speed for exploration is improved by learning fromother bees in all dimensions and (2) the individualrsquos learningsources for exploitation are enriched by learning fromboth itshistorical information and the superior individualsThenovelstrategies can significantly enhance the global exploration
Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
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8 Mathematical Problems in Engineering
bees and scout bees The goal of the whole bees is tocollaboratively find the largest source of nectar The actuallocation of the food source represents a possible solution forthe optimization problems in ABC and the density of nectarcorresponds to a fitness value of solutionThenumber of foodsources represents the swarm size PS
In the iteration each employed bee explores the foodsource using the following
119887V119889119898 = 119909119889119898 + 120601119889119898 (119909119889119898 minus 119909119889119902) 119898 = 119902 (20)
where 119887V119889119898 denotes a candidate food source positionmm= 12 PS 120601119889119898 is a randomly produced value within [-1 1] 119909119889119898refers to the corresponding food source and 119909119889119902 is a randomlyselected food source
Each onlooker bee randomly selects its food sourcem for further refinement with a probability 119901119898 which isdetermined as follows
119901119898 =119891119894119905119899119890119904119904119898
sum119878119904=1 119891119894119905119899119890119904119904119904(21)
where119891119894119905119899119890119904119904119898 is the quality of them-th food source For theminimization problem the 119891119894119905119899119890119904119904119898 can be calculated usingthe following
119891119894119905119899119890119904119904119898 =
1(1 + 119891119898)
if 119891119898 ge 01 + 119886119887119904 (119891119898) if 119891119898 le 0
(22)
where 119891119898 is the m-th objective function value The value ofldquolimitrdquo to abandon the poor food source is suggested to be setto PSlowastD [47] The main steps of ABC are given below
(1) Initialize the number of food sources the limit andthe maximum number of iterations
(2) Randomly generate the positions of food sources inproblem landscape
(3) Evaluate the fitness value of food sources foundcurrently
(4) Each employed bee explores between a randomexem-plar and their own food source using (20)
(5) Apply greedy selection process to select the best PSpositions and record the updated food sources
(6) Calculate the probability of the food sources withwhich onlooker bees are going to follow by (21)
(7) Produce new solutionusing (20) for the onlooker beesdepending on 119901119894
(8) Conduct greedy selection and update food sourceinformation for onlooker bees
(9) Abandon the food sources with poor nectar and letscouts search for new food sources
(10) Terminate if the stop criteria are met otherwise go to(4)
43 Superior Tracking Artificial Bee Colony Algorithm Asa newly proposed algorithm while promising ABC stillsuffers from two weaknesses First the convergence speed isrelatively slow compared tomany existing swarm intelligencealgorithms Second the capability of exploring global optimais still underperforming on many multimodal problems [48]In the original search behavior of ABC only one dimensionof a bee is selected to learn and renew in each round ofinformation updating This search rule may result in the slowconvergence or inferior exploring capability [49] To addressthis issue the STABC is introduced to improve the searchcapability and convergence speed for global optimization
In STABC the employed bees and onlooker bees areupdated in accordance with the following equation
119887V119898 = 119909119898 + 119903119898 (119909119898 minus 119878119873119898) (23)
where 119887V119898 represents the food position of the m-th (m=1 2 PS) food source to be updated 119903119898 refers to arandomly generated D-dimensional vector and SN is the D-dimensional constructed exemplar for tracking in which theelements are either from itself or from the other superiorfood sources randomly chosen by roulette selection andtournament selection
The detailed procedure of constructing SNm is presentedas follows
(1) Initialize a given probability Pr to decide whichexemplar the current bee should chase itself or theother superior neighbors in the population
(2) For each dimension of 119878119873119889119898 (d = 1 toD) a valuewithin[0 1] is randomly generated(3) If the generated value is larger than Pr two food
positions are randomly chosen for comparison andthe d-th dimension of the better one will be learnedotherwise 119878119873119889119898 will be itself
(4) Repeat the above steps till all dimensions of SNm aredetermined
In STABC all elements of an individual will be likely toupdate at each iteration As a result each bee either exploitsthe local optima by learning from itself or explores the globallandscape by chasing the other individuals in the populationThis search strategy accelerates the convergence speeds ofthe population In addition it remains from ABC originalproperties that every individual could be learning exemplarsFigure 2 displays the flow chart of the STABC algorithm
44 Implementation of the SI-Based Optimizers for Cell For-mation In the proposed mathematical model the computa-tional complexity is dependent on the variable size of 119885119888119896119897119895which is equal to 119888 lowast 119896 lowast 119897 lowast 119895 The search dimension ofsolutionZcklj will be too large to optimize using the traditionalmathematical methods Our preliminary experiment indi-cates that it is extremely hard to obtain a suboptimum if thevariables are without proper treatment Meanwhile a feasiblesolution Z would be hard to locate due to the complexityand discontinuity of constraints To address these issues a SI-based metaheuristic is proposed to explore the global optima
Mathematical Problems in Engineering 9
Begin
Initialize food source positions Setting criteria and itc = 1
Fitness value calculation
Evaluate new solution
Greedy SelectionCalculate the probability
of the food source
Determine the chosenfood source by the
onlooker bees
Output
N
Y
itc gt criteria
itc = itc+1
Greedy SelectionRandomly generate a new
position for the abandonedfood sources
Evaluate new solution
itc iteration counter
Trial successfully update record of each food source
Pr a threshold
randi an interger from a uniform discrete distribution
FS the position of the food sources
FV fitness value
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Figure 2 Flowchart of the STABC algorithm
While implementing the swarm-based optimizers for cross-trained worker assignment problem three important issuesshould be considered encoding decoding and constrainshandling
An effective encoding method is developed in this studyThe original 0-1 planning problem is transformed into aninteger programming problem in which the targeting skilllevel and theworker are allocated to each task tomeet the pro-duction requirements For the population initialization them-th individual is represented as 119909119898 = [1199091198981 1199091198982 119909119898119895]j = 1 2 J where J denotes the value of tasks The range ofthe algorithmic representation 1199091198981 is [1 k+l]
In the decoding process the worker and skill levelindices need to be determined through the algorithmicrepresentation A cross-reference matrix is generated here forconverting individual 119909119898 to the indices of worker and skilllevel Details of procedures involved in the decoding processfor 119909119898 are shown in Figure 3
For the constraints handling process the basic penaltyfunctionmethod is adopted [50] Once the objective functionvalue of 119909119898 and the corresponding constraint violation havebeen obtained the penalty value is added to the objectivefunction value of 119909119898
Begin
Y
1 2 hellip K1 1 2 hellip K2 hellip hellip hellip helliphellip hellip hellip hellip hellipL hellip hellip hellip K+L N
Y
Y
N
c = 1 j = 1empty Zcklj
p = 1P
Cross-reference
Inputxmj
Outputindexvalue
kl
Z(cklj) = 1j = j+1
j gt J
c = c+1j =1
c gt C
Output Zcklj
any(Tcpj)gt0
Figure 3 Decoding procedure
5 Computational Experiment
To validate effectiveness and efficiency of the proposedmathematical model and optimizers computational ex-periments are performed in this section Ten problemsare randomly generated based on previous research(can be accessed at httpsdrivegooglecomopenid=0B18FVuMxAffXLW1mRzVLczlyem8) The experiments areimplemented using MATLAB R2012a and the desktop iswith Intel Core i5 CPU 320GHz and 8GB memory
51 Experiment Settings The cross-trained worker assign-ment problem is based on the formed manufacturing cellsin this research that is part and tasks types had beenfixed after cell formation in CMS Ten cell formation prob-lems are selected from previous literature (see Table 3) Asthe problems are generated with different sizes they arenot directly correlated to each other The different typesof problem size can comprehensively evaluate the scalableperformance of the proposed method on this mathematical
10 Mathematical Problems in Engineering
Table 3 Dimension of test problems
Problem No Number ofParts Tasks Cells Workers
P1 [34] 5 5 2 5P2 [35] 7 5 2 5P3 [36] 6 6 2 6P4 [37] 8 9 2 9P5 [38] 10 8 3 8P6 [36] 8 10 3 10P7 [39] 10 10 3 10P8 [35] 12 10 3 10P9 [40] 18 10 3 10P10 [41] 22 11 3 11
Table 4 Pattern of data generation
Parameters Values119879119862119895 lowastDU(500 1000)119879119888119901119895 DU(01 15)119889119888119901119895 DU(50 150)119882119896119895 Randomly generated in set (0 07 08 09 1 11)119908119897 w1=07 w2=08 w3=09 w4=10 w5=11lowastDU(m n) means discrete uniform distribution varying between m and nThe unit of time is minute
model The additional parameters are randomly generatedas shown in Table 4 To allow one-to-one correspondencebetween workers and tasks in extreme situation we assumedthat the number of available workers is equal to the numberof tasks in CMS The available working time of each workerin a shift is calculated as 8 hlowast60mlowast85=408m The trainingbudget in the factory is sufficient Penalty cost of workloadimbalance 120572 is assumed to be 100 With respect to the trade-off between training expenditure and workload balanceldquo1205871=1 1205872=10rdquo stands for the first situation which refers tothe pursuit of more exact workload balance although moretraining cost should be spent while ldquo1205871=10 1205872=1rdquo standsfor the second situation which refers to saving training costalthough workload balance may not be enforced very well
Themaximum number of iterations is set as 20000 whereall the candidate algorithms are found to converge fast Forthe standard PSO the constant120593=41 and the values120594=07298and r1=r2=205 are gathered (Bratton and Kennedy 2007)For the STABC the range of 119903119898 is empirically set as [0149] which could be a time-varying function as well [49]With respect to the threshold probability Pr of STABC themethod introduced in Liang et alrsquos research [51] is adoptedThe population size is set at 30 for all algorithms [47]
52 Experimental Results Each problem is run indepen-dently 20 times with the four algorithms (GPSO LPSO ABCand STABC) The CPU time for each run does not exceed90s In Table 5 119874119865119881119887 119874119865119881119908 and 119874119865119881119886 represent the bestworst and average objective function values (OFV) of theten problems after 20 runs under the two situations (1205871=1
0
25000
50000
75000
100000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=1 2=10
GPSOLPSO
ABCSTABC
Figure 4 119874119865119881119887 results for the case of 1205871=1 1205872=10
1205872=10) and (1205871=10 1205872=1)The best solutions of119874119865119881119887119874119865119881119908and 119874119865119881119886 found by the four algorithms are shown in boldBased on experimental results three measures to evaluate theeffectiveness of STABC algorithm are defined as follows(1) 119861119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119887 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119861119866119866119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119887byGPSO over 119874119865119881119887 by STABC(2) 119882119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119908between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance119882119866119871119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119908 byLPSO over 119874119865119881119908 by STABC(3) 119860119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119886 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119860119866119860119861119862119878119879119860119861119862 means the rising percentage of 119874119865119881119886 byABC over 119874119865119881119886 by STABC
With respect to the abovemeasures the presented STABCis employed as the basis to compare the performance of theinvolved algorithms A positive value indicates that STABCoutperforms the other algorithms on the optimized problem
Table 6 shows the comparison results on the ten problemsunder the two situations (1205871=1 1205872=10) and (1205871=10 1205872=1) Wesee thatmost of119861119866lowast119878119879119860119861119862119882119866lowast119878119879119860119861119862119860119866lowast119878119879119860119861119862 and all averagevalues are positive Thus better results with respect to119874119865119881119887119874119865119881119908 and 119874119865119881119886 can be attained by STABC compared toGPSO LPSO and ABC under both situations (1205871=1 1205872=10)and (1205871=10 1205872=1)
Figures 4 and 5 compare the 119874119865119881119887obtained by GPSOLPSO ABC and STABC (see Table 5)They demonstrate thatthe best solutions of STABC are better than the others Forthe relatively simple small-size problems such as problems1 2 and 3 most of the algorithms can easily identify thebest results With the increase of problem size STABCoutperforms the other algorithms on the relatively large-sizeproblems The improvement of STBACrsquos search capabilitycan be attributed to two properties (1) each individualrsquoslearning speed for exploration is improved by learning fromother bees in all dimensions and (2) the individualrsquos learningsources for exploitation are enriched by learning fromboth itshistorical information and the superior individualsThenovelstrategies can significantly enhance the global exploration
Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
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Submit your manuscripts atwwwhindawicom
Mathematical Problems in Engineering 9
Begin
Initialize food source positions Setting criteria and itc = 1
Fitness value calculation
Evaluate new solution
Greedy SelectionCalculate the probability
of the food source
Determine the chosenfood source by the
onlooker bees
Output
N
Y
itc gt criteria
itc = itc+1
Greedy SelectionRandomly generate a new
position for the abandonedfood sources
Evaluate new solution
itc iteration counter
Trial successfully update record of each food source
Pr a threshold
randi an interger from a uniform discrete distribution
FS the position of the food sources
FV fitness value
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Generate SNi i = xi + ri (xi - SNi)
xnewi = xi + i
Figure 2 Flowchart of the STABC algorithm
While implementing the swarm-based optimizers for cross-trained worker assignment problem three important issuesshould be considered encoding decoding and constrainshandling
An effective encoding method is developed in this studyThe original 0-1 planning problem is transformed into aninteger programming problem in which the targeting skilllevel and theworker are allocated to each task tomeet the pro-duction requirements For the population initialization them-th individual is represented as 119909119898 = [1199091198981 1199091198982 119909119898119895]j = 1 2 J where J denotes the value of tasks The range ofthe algorithmic representation 1199091198981 is [1 k+l]
In the decoding process the worker and skill levelindices need to be determined through the algorithmicrepresentation A cross-reference matrix is generated here forconverting individual 119909119898 to the indices of worker and skilllevel Details of procedures involved in the decoding processfor 119909119898 are shown in Figure 3
For the constraints handling process the basic penaltyfunctionmethod is adopted [50] Once the objective functionvalue of 119909119898 and the corresponding constraint violation havebeen obtained the penalty value is added to the objectivefunction value of 119909119898
Begin
Y
1 2 hellip K1 1 2 hellip K2 hellip hellip hellip helliphellip hellip hellip hellip hellipL hellip hellip hellip K+L N
Y
Y
N
c = 1 j = 1empty Zcklj
p = 1P
Cross-reference
Inputxmj
Outputindexvalue
kl
Z(cklj) = 1j = j+1
j gt J
c = c+1j =1
c gt C
Output Zcklj
any(Tcpj)gt0
Figure 3 Decoding procedure
5 Computational Experiment
To validate effectiveness and efficiency of the proposedmathematical model and optimizers computational ex-periments are performed in this section Ten problemsare randomly generated based on previous research(can be accessed at httpsdrivegooglecomopenid=0B18FVuMxAffXLW1mRzVLczlyem8) The experiments areimplemented using MATLAB R2012a and the desktop iswith Intel Core i5 CPU 320GHz and 8GB memory
51 Experiment Settings The cross-trained worker assign-ment problem is based on the formed manufacturing cellsin this research that is part and tasks types had beenfixed after cell formation in CMS Ten cell formation prob-lems are selected from previous literature (see Table 3) Asthe problems are generated with different sizes they arenot directly correlated to each other The different typesof problem size can comprehensively evaluate the scalableperformance of the proposed method on this mathematical
10 Mathematical Problems in Engineering
Table 3 Dimension of test problems
Problem No Number ofParts Tasks Cells Workers
P1 [34] 5 5 2 5P2 [35] 7 5 2 5P3 [36] 6 6 2 6P4 [37] 8 9 2 9P5 [38] 10 8 3 8P6 [36] 8 10 3 10P7 [39] 10 10 3 10P8 [35] 12 10 3 10P9 [40] 18 10 3 10P10 [41] 22 11 3 11
Table 4 Pattern of data generation
Parameters Values119879119862119895 lowastDU(500 1000)119879119888119901119895 DU(01 15)119889119888119901119895 DU(50 150)119882119896119895 Randomly generated in set (0 07 08 09 1 11)119908119897 w1=07 w2=08 w3=09 w4=10 w5=11lowastDU(m n) means discrete uniform distribution varying between m and nThe unit of time is minute
model The additional parameters are randomly generatedas shown in Table 4 To allow one-to-one correspondencebetween workers and tasks in extreme situation we assumedthat the number of available workers is equal to the numberof tasks in CMS The available working time of each workerin a shift is calculated as 8 hlowast60mlowast85=408m The trainingbudget in the factory is sufficient Penalty cost of workloadimbalance 120572 is assumed to be 100 With respect to the trade-off between training expenditure and workload balanceldquo1205871=1 1205872=10rdquo stands for the first situation which refers tothe pursuit of more exact workload balance although moretraining cost should be spent while ldquo1205871=10 1205872=1rdquo standsfor the second situation which refers to saving training costalthough workload balance may not be enforced very well
Themaximum number of iterations is set as 20000 whereall the candidate algorithms are found to converge fast Forthe standard PSO the constant120593=41 and the values120594=07298and r1=r2=205 are gathered (Bratton and Kennedy 2007)For the STABC the range of 119903119898 is empirically set as [0149] which could be a time-varying function as well [49]With respect to the threshold probability Pr of STABC themethod introduced in Liang et alrsquos research [51] is adoptedThe population size is set at 30 for all algorithms [47]
52 Experimental Results Each problem is run indepen-dently 20 times with the four algorithms (GPSO LPSO ABCand STABC) The CPU time for each run does not exceed90s In Table 5 119874119865119881119887 119874119865119881119908 and 119874119865119881119886 represent the bestworst and average objective function values (OFV) of theten problems after 20 runs under the two situations (1205871=1
0
25000
50000
75000
100000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=1 2=10
GPSOLPSO
ABCSTABC
Figure 4 119874119865119881119887 results for the case of 1205871=1 1205872=10
1205872=10) and (1205871=10 1205872=1)The best solutions of119874119865119881119887119874119865119881119908and 119874119865119881119886 found by the four algorithms are shown in boldBased on experimental results three measures to evaluate theeffectiveness of STABC algorithm are defined as follows(1) 119861119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119887 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119861119866119866119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119887byGPSO over 119874119865119881119887 by STABC(2) 119882119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119908between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance119882119866119871119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119908 byLPSO over 119874119865119881119908 by STABC(3) 119860119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119886 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119860119866119860119861119862119878119879119860119861119862 means the rising percentage of 119874119865119881119886 byABC over 119874119865119881119886 by STABC
With respect to the abovemeasures the presented STABCis employed as the basis to compare the performance of theinvolved algorithms A positive value indicates that STABCoutperforms the other algorithms on the optimized problem
Table 6 shows the comparison results on the ten problemsunder the two situations (1205871=1 1205872=10) and (1205871=10 1205872=1) Wesee thatmost of119861119866lowast119878119879119860119861119862119882119866lowast119878119879119860119861119862119860119866lowast119878119879119860119861119862 and all averagevalues are positive Thus better results with respect to119874119865119881119887119874119865119881119908 and 119874119865119881119886 can be attained by STABC compared toGPSO LPSO and ABC under both situations (1205871=1 1205872=10)and (1205871=10 1205872=1)
Figures 4 and 5 compare the 119874119865119881119887obtained by GPSOLPSO ABC and STABC (see Table 5)They demonstrate thatthe best solutions of STABC are better than the others Forthe relatively simple small-size problems such as problems1 2 and 3 most of the algorithms can easily identify thebest results With the increase of problem size STABCoutperforms the other algorithms on the relatively large-sizeproblems The improvement of STBACrsquos search capabilitycan be attributed to two properties (1) each individualrsquoslearning speed for exploration is improved by learning fromother bees in all dimensions and (2) the individualrsquos learningsources for exploitation are enriched by learning fromboth itshistorical information and the superior individualsThenovelstrategies can significantly enhance the global exploration
Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
Hindawiwwwhindawicom Volume 2018
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Hindawiwwwhindawicom Volume 2018
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10 Mathematical Problems in Engineering
Table 3 Dimension of test problems
Problem No Number ofParts Tasks Cells Workers
P1 [34] 5 5 2 5P2 [35] 7 5 2 5P3 [36] 6 6 2 6P4 [37] 8 9 2 9P5 [38] 10 8 3 8P6 [36] 8 10 3 10P7 [39] 10 10 3 10P8 [35] 12 10 3 10P9 [40] 18 10 3 10P10 [41] 22 11 3 11
Table 4 Pattern of data generation
Parameters Values119879119862119895 lowastDU(500 1000)119879119888119901119895 DU(01 15)119889119888119901119895 DU(50 150)119882119896119895 Randomly generated in set (0 07 08 09 1 11)119908119897 w1=07 w2=08 w3=09 w4=10 w5=11lowastDU(m n) means discrete uniform distribution varying between m and nThe unit of time is minute
model The additional parameters are randomly generatedas shown in Table 4 To allow one-to-one correspondencebetween workers and tasks in extreme situation we assumedthat the number of available workers is equal to the numberof tasks in CMS The available working time of each workerin a shift is calculated as 8 hlowast60mlowast85=408m The trainingbudget in the factory is sufficient Penalty cost of workloadimbalance 120572 is assumed to be 100 With respect to the trade-off between training expenditure and workload balanceldquo1205871=1 1205872=10rdquo stands for the first situation which refers tothe pursuit of more exact workload balance although moretraining cost should be spent while ldquo1205871=10 1205872=1rdquo standsfor the second situation which refers to saving training costalthough workload balance may not be enforced very well
Themaximum number of iterations is set as 20000 whereall the candidate algorithms are found to converge fast Forthe standard PSO the constant120593=41 and the values120594=07298and r1=r2=205 are gathered (Bratton and Kennedy 2007)For the STABC the range of 119903119898 is empirically set as [0149] which could be a time-varying function as well [49]With respect to the threshold probability Pr of STABC themethod introduced in Liang et alrsquos research [51] is adoptedThe population size is set at 30 for all algorithms [47]
52 Experimental Results Each problem is run indepen-dently 20 times with the four algorithms (GPSO LPSO ABCand STABC) The CPU time for each run does not exceed90s In Table 5 119874119865119881119887 119874119865119881119908 and 119874119865119881119886 represent the bestworst and average objective function values (OFV) of theten problems after 20 runs under the two situations (1205871=1
0
25000
50000
75000
100000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=1 2=10
GPSOLPSO
ABCSTABC
Figure 4 119874119865119881119887 results for the case of 1205871=1 1205872=10
1205872=10) and (1205871=10 1205872=1)The best solutions of119874119865119881119887119874119865119881119908and 119874119865119881119886 found by the four algorithms are shown in boldBased on experimental results three measures to evaluate theeffectiveness of STABC algorithm are defined as follows(1) 119861119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119887 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119861119866119866119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119887byGPSO over 119874119865119881119887 by STABC(2) 119882119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119908between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance119882119866119871119875119878119874119878119879119860119861119862 means the rising percentage of 119874119865119881119908 byLPSO over 119874119865119881119908 by STABC(3) 119860119866lowast119878119879119860119861119862 denotes the gap of 119874119865119881119886 between STABC
and any other algorithms (GPSO LPSO or ABC) Forinstance 119860119866119860119861119862119878119879119860119861119862 means the rising percentage of 119874119865119881119886 byABC over 119874119865119881119886 by STABC
With respect to the abovemeasures the presented STABCis employed as the basis to compare the performance of theinvolved algorithms A positive value indicates that STABCoutperforms the other algorithms on the optimized problem
Table 6 shows the comparison results on the ten problemsunder the two situations (1205871=1 1205872=10) and (1205871=10 1205872=1) Wesee thatmost of119861119866lowast119878119879119860119861119862119882119866lowast119878119879119860119861119862119860119866lowast119878119879119860119861119862 and all averagevalues are positive Thus better results with respect to119874119865119881119887119874119865119881119908 and 119874119865119881119886 can be attained by STABC compared toGPSO LPSO and ABC under both situations (1205871=1 1205872=10)and (1205871=10 1205872=1)
Figures 4 and 5 compare the 119874119865119881119887obtained by GPSOLPSO ABC and STABC (see Table 5)They demonstrate thatthe best solutions of STABC are better than the others Forthe relatively simple small-size problems such as problems1 2 and 3 most of the algorithms can easily identify thebest results With the increase of problem size STABCoutperforms the other algorithms on the relatively large-sizeproblems The improvement of STBACrsquos search capabilitycan be attributed to two properties (1) each individualrsquoslearning speed for exploration is improved by learning fromother bees in all dimensions and (2) the individualrsquos learningsources for exploitation are enriched by learning fromboth itshistorical information and the superior individualsThenovelstrategies can significantly enhance the global exploration
Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
Hindawiwwwhindawicom Volume 2018
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Hindawiwwwhindawicom Volume 2018
Mathematical Problems in Engineering
Applied MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Probability and StatisticsHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
Mathematical PhysicsAdvances in
Complex AnalysisJournal of
Hindawiwwwhindawicom Volume 2018
OptimizationJournal of
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Hindawiwwwhindawicom Volume 2018
Engineering Mathematics
International Journal of
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Operations ResearchAdvances in
Journal of
Hindawiwwwhindawicom Volume 2018
Function SpacesAbstract and Applied AnalysisHindawiwwwhindawicom Volume 2018
International Journal of Mathematics and Mathematical Sciences
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Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
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Mathematical Problems in Engineering 11
Table5Re
sults
from
GPS
OL
PSOA
BCand
STABC
GPS
OLP
SOABC
STABC
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
119874119865119881119887
119874119865119881119908
119874119865119881119886
P11205871=1120587
2=10
33183
3330
733
212
33183
33344
33285
32852
42983
35125
3283
943122
34597
1205871=101205872
=141163
4195
841
590
41258
42753
42152
38955
48235
44105
3810
548837
42540
P21205871=1120587
2=10
3260
732
667
32638
32596
32714
3264
832259
32959
3237
032
259
33204
32499
1205871=101205872
=135260
35865
35293
35216
3586
035330
32602
40752
35266
3260
240
907
3339
2
P31205871=1120587
2=10
33497
33782
3360
733453
33769
33619
32772
33116
32885
3277
232
864
3280
21205871=101205872
=142745
44415
43450
42745
44344
43563
36861
41403
38321
3681
139
207
3742
4
P41205871=1120587
2=10
53681
5700
955124
53277
5604
554
768
63133
76480
67822
5249
364
168
60957
1205871=101205872
=166237
80183
75246
65879
81657
7606
455113
91142
79567
5251
577
852
6748
2
P51205871=1120587
2=10
54720
5564
455089
54771
55589
55163
53669
55151
54324
5360
754
088
5387
91205871=101205872
=159274
67264
63857
59871
69167
64942
52293
63298
57622
5153
657
031
5382
6
P61205871=1120587
2=10
55149
66403
60150
55108
66335
56981
4621
963596
54613
53296
5439
253
768
1205871=101205872
=170131
84437
79483
72363
86381
80558
55765
64943
61086
5166
461
076
5572
6
P71205871=1120587
2=10
65351
68255
66758
65730
69136
67249
64034
74700
65529
6346
464
682
6402
01205871=101205872
=182555
99389
92564
87731
103806
96119
66279
87778
76697
6302
674
477
6879
8
P81205871=1120587
2=10
75074
78381
7604
175630
7812
07644
673638
85692
80359
7363
783820
78977
1205871=101205872
=184676
97413
91203
85879
102599
93956
72901
90037
81322
7255
781
016
7790
5
P91205871=1120587
2=10
75750
78238
77138
76227
78917
77378
74097
85694
7666
773
342
7496
074
237
1205871=101205872
=197288
117201
105674
95973
120132
108403
81629
105846
89569
7117
692
650
7930
4
P10
1205871=1120587
2=10
86208
89887
88252
85905
98570
89542
85065
9544
887622
8388
186
995
8482
11205871=101205872
=194291
132599
121452
11040
4139528
123986
87300
121262
103559
8520
010
1088
9167
5
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
Hindawiwwwhindawicom Volume 2018
MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Mathematical Problems in Engineering
Applied MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Probability and StatisticsHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
Mathematical PhysicsAdvances in
Complex AnalysisJournal of
Hindawiwwwhindawicom Volume 2018
OptimizationJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Engineering Mathematics
International Journal of
Hindawiwwwhindawicom Volume 2018
Operations ResearchAdvances in
Journal of
Hindawiwwwhindawicom Volume 2018
Function SpacesAbstract and Applied AnalysisHindawiwwwhindawicom Volume 2018
International Journal of Mathematics and Mathematical Sciences
Hindawiwwwhindawicom Volume 2018
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
Hindawiwwwhindawicom Volume 2018Volume 2018
Numerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisAdvances inAdvances in Discrete Dynamics in
Nature and SocietyHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom
Dierential EquationsInternational Journal of
Volume 2018
Hindawiwwwhindawicom Volume 2018
Decision SciencesAdvances in
Hindawiwwwhindawicom Volume 2018
AnalysisInternational Journal of
Hindawiwwwhindawicom Volume 2018
Stochastic AnalysisInternational Journal of
Submit your manuscripts atwwwhindawicom
12 Mathematical Problems in Engineering
Table6Perfo
rmance
comparis
onam
ongGPS
OL
PSOA
BCand
STABC
119861119866119866119875119878119874
119878119879119860119861119862
119882119866119866119875119878119874
S119879119860119861119862
119860119866119866119875119878119874
119878119879119860119861119862
119861119866119871119875119878119874
119878119879119860119861119862
119882119866119871119875119878119874
119878119879119860119861119862
119860119866119871119875119878119874
119878119879119860119861119862
119861119866119860119861119862119878119879119860119861119862
119882119866119860119861119862119878119879119860119861119862
119860119866119860119861119862119878119879119860119861119862
P11205871=1120587
2=10
10
-228
-40
10
-227
-38
00
-03
15
1205871=101205872
=180
-141
-22
83
-125
-09
22
-12
37
P21205871=1120587
2=10
11
-16
04
10
-15
05
00
-07
-04
1205871=101205872
=182
-123
57
80
-123
58
00
-04
56
P31205871=1120587
2=10
22
28
25
21
28
25
00
08
03
1205871=101205872
=1161
133
161
161
131
164
01
56
24
P41205871=1120587
2=10
23
-112
-96
15
-127
-102
203
192
113
1205871=101205872
=1261
30
115
254
49
127
49
171
179
P51205871=1120587
2=10
21
29
22
22
28
24
01
20
08
1205871=101205872
=1150
179
186
162
213
207
15
110
71
P61205871=1120587
2=10
35
221
119
34
220
60
-133
169
16
1205871=101205872
=1357
382
426
401
414
446
79
63
96
P71205871=1120587
2=10
30
55
43
36
69
50
09
155
24
1205871=101205872
=1310
334
345
392
394
397
52
179
115
P81205871=1120587
2=10
20
-65
-37
27
-68
-32
00
22
17
1205871=101205872
=1167
202
171
184
266
206
05
111
44
P91205871=1120587
2=10
33
44
39
39
53
42
10
143
33
1205871=101205872
=1367
265
333
348
297
367
147
142
129
P10
1205871=1120587
2=10
28
33
40
24
133
56
14
97
33
1205871=101205872
=1107
312
325
296
380
352
25
200
130
Mean
114
78
11
113
0
99
120
2
59
15
7
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
Hindawiwwwhindawicom Volume 2018
MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Mathematical Problems in Engineering
Applied MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Probability and StatisticsHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
Mathematical PhysicsAdvances in
Complex AnalysisJournal of
Hindawiwwwhindawicom Volume 2018
OptimizationJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Engineering Mathematics
International Journal of
Hindawiwwwhindawicom Volume 2018
Operations ResearchAdvances in
Journal of
Hindawiwwwhindawicom Volume 2018
Function SpacesAbstract and Applied AnalysisHindawiwwwhindawicom Volume 2018
International Journal of Mathematics and Mathematical Sciences
Hindawiwwwhindawicom Volume 2018
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
Hindawiwwwhindawicom Volume 2018Volume 2018
Numerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisAdvances inAdvances in Discrete Dynamics in
Nature and SocietyHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom
Dierential EquationsInternational Journal of
Volume 2018
Hindawiwwwhindawicom Volume 2018
Decision SciencesAdvances in
Hindawiwwwhindawicom Volume 2018
AnalysisInternational Journal of
Hindawiwwwhindawicom Volume 2018
Stochastic AnalysisInternational Journal of
Submit your manuscripts atwwwhindawicom
Mathematical Problems in Engineering 13
0
20000
40000
60000
80000
100000
120000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
OFVb in the situation of 1=10 2=1
GPSOLPSO
ABCSTABC
Figure 5 119874119865119881119887 results for the case of 1205871=10 1205872=1
0300600900
120015001800
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Training Cost
1=1 2=101=10 2=1
Figure 6 Training costs obtained by STABC
capability and local exploitation capability especially in large-size problems which are proved by the experimental results
The CPU time of all test problems by the four algorithmsfluctuates between 10s and 90s Although the advantage ofcomputational efficiency of STABC is not significant amongthe four algorithms it is efficient to obtain solution of theproblem In contrast the computational software Lingo isunable to obtain any feasible results in half an hour for mostof the experiments
In addition we compare the training cost and workloadbalance associated with the ten problems between the twoscenarios (1205871=11205872=10) and (1205871=101205872=1) see Figures 6 and 7All the training cost andworkload balance in scenario (1205871=101205872=1) is equal to or lower than that of scenario (1205871=1 1205872=10)This indicates that less training effort which is in the scenario(1205871=10 1205872=1) will lead to less balanced workload in allthe test problems though corresponding worker assignmentis reasonable It indicates that the cross-training strategyobtained by our proposed approach is effective while seekingworkload balance
6 Conclusion and Future Research
A novel mathematical programming model for solving theworker assignment problem in CMS while incorporatingcross-training is presented in this paper Then the swarmintelligence optimizers are introduced to obtain promisingsolution
800
850
900
950
1000
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10
Workload Balance
1=1 2=101=10 2=1
Figure 7 Workload balance results obtained by STABC
The proposed model defines the objective function asminimum training cost optimizedworkload balance and theminimum number of assigned workers based on consideringcustomer demand available time task time limited trainingcost and initial skill level of worker This model not onlyassigns suitable workers with the desired skill levels to thevarious tasks in multiple cells but also determines necessityof skill enhancement by quantifying skill level needed toavoid excessive training As for the trade-off between trainingexpenditure and workload balance of workers decision-maker has more flexible selections on solution based onthe preference to cross-training or workload balance Theexperimental results demonstrate that the proposed model iseffective and feasible to produce interaction among cells forsolving worker assignment problem with reasonable cross-training policy
In addition the efficient swarm intelligence metaheuris-tics including GPSO LPSO and ABC are employed to solvethe CMS model To avoid premature convergence and lowexploitation STABCwith the enhanced information learningstrategy is proposed for the complex cross-trained workerassignment problem In this strategy an all-dimension-wiselearning mechanism is proposed to enable each individualto both exploit itself and track the promising individuals Tocompare the performances of the four algorithms we executeten computational experiments with respect to the severaldefinedmeasuresThe results reveal that STABC significantlyoutperforms the comparison algorithms in terms of thebest worst and average solutions of repeated experimentsWith increase in problem scale the performance differencesbetween STABC and PSO are more remarkable In additionthe convergence capability of the STABC is observed moreefficiently than the others over the experiments
In future research we will consider more useful andpractical issues to allocate cross-trained workers into tasks inCMS such as quality level of worker learning and forgettingcapability and work-sharing mechanism Additionally weintend to extend this problem from divisional cell to rotatingcell which is the other primary type of manufacturing cell
Data Availability
The original experiment data used to support the findingsof this study have been deposited in the repository ldquoTheNational Science Digital Libraryrdquo ([httpsnsdloercommons
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
Hindawiwwwhindawicom Volume 2018
MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Mathematical Problems in Engineering
Applied MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Probability and StatisticsHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
Mathematical PhysicsAdvances in
Complex AnalysisJournal of
Hindawiwwwhindawicom Volume 2018
OptimizationJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Engineering Mathematics
International Journal of
Hindawiwwwhindawicom Volume 2018
Operations ResearchAdvances in
Journal of
Hindawiwwwhindawicom Volume 2018
Function SpacesAbstract and Applied AnalysisHindawiwwwhindawicom Volume 2018
International Journal of Mathematics and Mathematical Sciences
Hindawiwwwhindawicom Volume 2018
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
Hindawiwwwhindawicom Volume 2018Volume 2018
Numerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisAdvances inAdvances in Discrete Dynamics in
Nature and SocietyHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom
Dierential EquationsInternational Journal of
Volume 2018
Hindawiwwwhindawicom Volume 2018
Decision SciencesAdvances in
Hindawiwwwhindawicom Volume 2018
AnalysisInternational Journal of
Hindawiwwwhindawicom Volume 2018
Stochastic AnalysisInternational Journal of
Submit your manuscripts atwwwhindawicom
14 Mathematical Problems in Engineering
orgcoursesexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelli-gence-meta-heuristicview]) The data are also enclosed asthe supplementary materials when we submitted themanuscript
Conflicts of Interest
The authors declare that they have no conflicts of interest
Acknowledgments
This work was partially supported by the National NaturalScience Foundation of China (Grant nos 71501132 71701079and 71371127) the Natural Science Foundation of GuangdongProvince (2016A030310067 and 2018A030310567) the ChinaPostdoctoral Science Foundation (2016M602528) and the2016 Tencent ldquoRhinoceros Birdsrdquo Scientific Research Foun-dation for Young Teachers of Shenzhen University
Supplementary Materials
The supplementary materials are the original data of 10experimental cases used to support the findings of this studywhich have been deposited in the repository ldquoThe NationalScienceDigital Libraryrdquo [httpsnsdloercommonsorgcours-esexperiment-data-cross-trained-worker-assignment-problem-in-cellular-manufacturing-system-using-swarm-intelligence-meta-heuristicview] Some types of the experiment datahave been employed from previous researches directlythe others have been randomly generated based onprevious research that had been explained in Section 5(Supplementary Materials)
References
[1] C Liu J Wang J Y-T Leung and K Li ldquoSolving cellformation and task scheduling in cellularmanufacturing systemby discrete bacteria foraging algorithmrdquo International Journal ofProduction Research vol 54 no 3 pp 923ndash944 2016
[2] G Papaioannou and J M Wilson ldquoThe evolution of cellformation problem methodologies based on recent studies(1997ndash2008) review and directions for future researchrdquo Euro-pean Journal of Operational Research vol 206 no 3 pp 509ndash521 2010
[3] H M Selim R G Askin and A J Vakharia ldquoCell formation ingroup technology review evaluation and directions for futureresearchrdquoComputers amp Industrial Engineering vol 34 no 1 pp3ndash20 1998
[4] Y Yin and K Yasuda ldquoSimilarity coefficientmethods applied tothe cell formation problem a taxonomy and reviewrdquo Interna-tional Journal of Production Economics vol 101 no 2 pp 329ndash352 2006
[5] O Mutlu O Polat and A A Supciller ldquoAn iterative geneticalgorithm for the assembly line worker assignment and balanc-ing problem of type-IIrdquo Computers amp Operations Research vol40 no 1 pp 418ndash426 2013
[6] R R Inman W C Jordan and D E Blumenfeld ldquoChainedcross-training of assembly line workersrdquo International Journalof Production Research vol 42 no 10 pp 1899ndash1910 2004
[7] J Slomp J A C Bokhorst and EMolleman ldquoCross-training ina cellularmanufacturing environmentrdquoComputers amp IndustrialEngineering vol 48 no 3 pp 609ndash624 2005
[8] S Sayin and S Karabati ldquoAssigning cross-trained workers todepartments A two-stage optimization model to maximizeutility and skill improvementrdquo European Journal of OperationalResearch vol 176 no 3 pp 1643ndash1658 2007
[9] X Chu T Wu J D Weir Y Shi B Niu and L LildquoLearningndashinteractionndashdiversification framework for swarmintelligence optimizers a unified perspectiverdquo Neural Comput-ing and Applications pp 1ndash21
[10] X Chu S X Xu F Cai J Chen andQQin ldquoAn efficient auctionmechanism for regional logistics synchronizationrdquo Journal ofIntelligent Manufacturing pp 1ndash17 2018
[11] J Kennedy and R Eberhart ldquoParticle swarm optimizationrdquoin Proceedings of the IEEE International Conference on NeuralNetworks pp 1942ndash1948 Perth Australia December 1995
[12] D Karaboga ldquoAn idea based on honey bee swarm for numericaloptimizationrdquo Technical report-tr06 Erciyes university engi-neering faculty computer engineering department 2005
[13] W J Hopp E Tekin and M P Van Oyen ldquoBenefits of skillchaining in serial production lines with cross-trained workersrdquoManagement Science vol 50 no 1 pp 83ndash98 2004
[14] M C O Moreira M Ritt A M Costa and A A ChavesldquoSimple heuristics for the assembly line worker assignment andbalancing problemrdquo Journal of Heuristics vol 18 no 3 pp 505ndash524 2012
[15] H Parvin M P VanOyen D G Pandelis D PWilliams and JLee ldquoFixed task zone chaining Worker coordination and zonedesign for inexpensive cross-training in serial CONWIP linesrdquoInstitute of Industrial Engineers (IIE) IIE Transactions vol 44no 10 pp 894ndash914 2012
[16] M Saidi-Mehrabad M M Paydar and A Aalaei ldquoProductionplanning and worker training in dynamic manufacturing sys-temsrdquo Journal of Manufacturing Systems vol 32 no 2 pp 308ndash314 2013
[17] B Sungur and Y Yavuz ldquoAssembly line balancing with hierar-chical worker assignmentrdquo Journal of Manufacturing Systemsvol 37 pp 290ndash298 2015
[18] M B Aryanezhad V Deljoo and S M J Mirzapour Al-E-Hashem ldquoDynamic cell formation and the worker assignmentproblem A new modelrdquoThe International Journal of AdvancedManufacturing Technology vol 41 no 3-4 pp 329ndash342 2009
[19] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoDesigning a mathematical model for dynamic cellular manu-facturing systems considering production planning and workerassignmentrdquo Computers amp Mathematics with Applications AnInternational Journal vol 60 no 4 pp 1014ndash1025 2010
[20] I Mahdavi A Aalaei M M Paydar and M SolimanpurldquoMulti-objective cell formation and production planning indynamic virtual cellular manufacturing systemsrdquo InternationalJournal of Production Research vol 49 no 21 pp 6517ndash65372011
[21] M Bagheri and M Bashiri ldquoA new mathematical modeltowards the integration of cell formation with operator assign-ment and inter-cell layout problems in a dynamic environmentrdquoApplied Mathematical Modelling Simulation and Computationfor Engineering and Environmental Systems vol 38 no 4 pp1237ndash1254 2014
[22] F Niakan A Baboli T Moyaux and V Botta-Genoulaz ldquoA bi-objective model in sustainable dynamic cell formation problem
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
Hindawiwwwhindawicom Volume 2018
MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Mathematical Problems in Engineering
Applied MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Probability and StatisticsHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
Mathematical PhysicsAdvances in
Complex AnalysisJournal of
Hindawiwwwhindawicom Volume 2018
OptimizationJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Engineering Mathematics
International Journal of
Hindawiwwwhindawicom Volume 2018
Operations ResearchAdvances in
Journal of
Hindawiwwwhindawicom Volume 2018
Function SpacesAbstract and Applied AnalysisHindawiwwwhindawicom Volume 2018
International Journal of Mathematics and Mathematical Sciences
Hindawiwwwhindawicom Volume 2018
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
Hindawiwwwhindawicom Volume 2018Volume 2018
Numerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisAdvances inAdvances in Discrete Dynamics in
Nature and SocietyHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom
Dierential EquationsInternational Journal of
Volume 2018
Hindawiwwwhindawicom Volume 2018
Decision SciencesAdvances in
Hindawiwwwhindawicom Volume 2018
AnalysisInternational Journal of
Hindawiwwwhindawicom Volume 2018
Stochastic AnalysisInternational Journal of
Submit your manuscripts atwwwhindawicom
Mathematical Problems in Engineering 15
with skill-based worker assignmentrdquo Journal of ManufacturingSystems vol 38 pp 46ndash62 2016
[23] C Liu J Wang and J Y-T Leung ldquoWorker assignment andproduction planning with learning and forgetting in manufac-turing cells by hybrid bacteria foraging algorithmrdquo Computersamp Industrial Engineering vol 96 pp 162ndash179 2016
[24] R G Askin and Y Huang ldquoForming effective worker teamsfor cellular manufacturingrdquo International Journal of ProductionResearch vol 39 no 11 pp 2431ndash2451 2001
[25] B A Norman W Tharmmaphornphilas K L Needy BBidanda and R C Warner ldquoWorker assignment in cellularmanufacturing considering technical and human skillsrdquo Inter-national Journal of Production Research vol 40 no 6 pp 1479ndash1492 2002
[26] T Ertay and D Ruan ldquoData envelopment analysis based deci-sion model for optimal operator allocation in CMSrdquo EuropeanJournal of Operational Research vol 164 no 3 pp 800ndash8102005
[27] E L Fitzpatrick and R G Askin ldquoForming effective workerteams with multi-functional skill requirementsrdquo Computers ampIndustrial Engineering vol 48 no 3 pp 593ndash608 2005
[28] HJ Cesani Steudel ldquoA study of labor assignment flexibilityin cellular manufacturing systemsrdquo Computers amp IndustrialEngineering vol 48 no 3 pp 571ndash591 2005
[29] T McDonald K P Ellis E M Van Aken and C PatrickKoelling ldquoDevelopment andapplication of aworker assignmentmodel to evaluate a lean manufacturing cellrdquo InternationalJournal of Production Research vol 47 no 9 pp 2427ndash24472009
[30] R Mural A Puri and G Prabhakaran ldquoArtificial neuralnetworks based predictive model for worker assignment intovirtual cellsrdquo International Journal of Engineering Science andTechnology vol 2 no 1 2010
[31] G Egilmez B Erenay and G A Suer ldquoStochastic skill-basedmanpower allocation in a cellular manufacturing systemrdquoJournal of Manufacturing Systems vol 33 no 4 pp 578ndash5882014
[32] D Bratton and J Kennedy ldquoDefining a standard for particleswarm optimizationrdquo in Proceedings of the IEEE Swarm Intelli-gence Symposium (SIS rsquo07) pp 120ndash127 Honolulu Hawaii USAApril 2007
[33] G A Suer andR R Tummaluri ldquoMulti-period operator assign-ment considering skills learning and forgetting in labour-intensive cellsrdquo International Journal of Production Researchvol 46 no 2 pp 469ndash493 2008
[34] Y Won and K C Lee ldquoGroup technology cell formationconsidering operation sequences and production volumesrdquoInternational Journal of Production Research vol 39 no 13 pp2755ndash2768 2001
[35] R Sudhakara Pandian and S S Mahapatra ldquoManufacturingcell formation with production data using neural networksrdquoComputers amp Industrial Engineering vol 56 no 4 pp 1340ndash1347 2009
[36] L Wu and S Suzuki ldquoCell formation design with improvedsimilarity coefficient method and decomposed mathematicalmodelrdquo The International Journal of Advanced ManufacturingTechnology vol 79 no 5-8 pp 1335ndash1352 2015
[37] F Alhourani ldquoCellular manufacturing system design consider-ing machines reliability and parts alternative process routingsrdquoInternational Journal of Production Research vol 54 no 3 pp846ndash863 2016
[38] W Hung M Yang and E S Lee ldquoCell formation using fuzzyrelational clustering algorithmrdquo Mathematical and ComputerModelling vol 53 no 9-10 pp 1776ndash1787 2011
[39] I Mahdavi B Javadi K Fallah-Alipour and J Slomp ldquoDesign-ing a new mathematical model for cellular manufacturingsystem based on cell utilizationrdquo Applied Mathematics andComputation vol 190 no 1 pp 662ndash670 2007
[40] G Prabhakaran T N Janakiraman and M SachithanandamldquoManufacturing data-based combined dissimilarity coefficientfor machine cell formationrdquo The International Journal ofAdvancedManufacturing Technology vol 19 no 12 pp 889ndash8972002
[41] W Hachicha F Masmoudi and M Haddar ldquoFormation ofmachine groups andpart families in cellularmanufacturing sys-tems using a correlation analysis approachrdquo The InternationalJournal of Advanced Manufacturing Technology vol 36 no 11-12 pp 1157ndash1169 2008
[42] Yuquan Guo Xiongfei Li Yufei Tang and Jun Li ldquoHeuristicArtificial Bee Colony Algorithm for Uncovering Communityin Complex NetworksrdquoMathematical Problems in Engineeringvol 2017 Article ID 4143638 12 pages 2017
[43] Hamza Yapıcı and Nurettin Cetinkaya ldquoAn Improved ParticleSwarmOptimization AlgorithmUsing Eagle Strategy for PowerLossMinimizationrdquoMathematical Problems in Engineering vol2017 Article ID 1063045 11 pages 2017
[44] K E Stecke Y Yin I Kaku and Y Murase ldquoSeru (cell)and reverse conversion part I definition self-evolution andtypologyrdquo inWorking paper Yamagata University 2008
[45] M Clerc and J Kennedy ldquoThe particle swarm-explosion sta-bility and convergence in a multidimensional complex spacerdquoIEEE Transactions on Evolutionary Computation vol 6 no 1pp 58ndash73 2002
[46] J Kennedy and R Mendes ldquoPopulation structure and particleswarm performancerdquo in Proceedings of the Congress on Evolu-tionary Computation pp 1671ndash1676 Honolulu Hawaii USAMay 2002
[47] B Akay and D Karaboga ldquoParameter Tuning for the ArtificialBee Colony Algorithmrdquo in Computational Biology Journalvol 5796 of Lecture Notes in Computer Science pp 608ndash619Springer Berlin Heidelberg Berlin Heidelberg 2009
[48] D Karaboga B Gorkemli C Ozturk and N Karaboga ldquoAcomprehensive survey artificial bee colony (ABC) algorithmand applicationsrdquo Artificial Intelligence Review vol 42 pp 21ndash57 2014
[49] X Chu G Hu B Niu L Li and Z Chu ldquoAn superiortracking artificial bee colony for global optimization problemsrdquoin Proceedings of the 2016 IEEE Congress on EvolutionaryComputation CEC 2016 pp 2712ndash2717 Canada July 2016
[50] Z Michalewicz and M Schoenauer ldquoEvolutionary algorithmsfor constrained parameter optimization problemsrdquo Evolution-ary Computation vol 4 no 1 pp 1ndash32 1996
[51] J J Liang A K Qin P N Suganthan and S BaskarldquoComprehensive learning particle swarm optimizer for globaloptimization of multimodal functionsrdquo IEEE Transactions onEvolutionary Computation vol 10 no 3 pp 281ndash295 2006
Hindawiwwwhindawicom Volume 2018
MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Mathematical Problems in Engineering
Applied MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Probability and StatisticsHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
Mathematical PhysicsAdvances in
Complex AnalysisJournal of
Hindawiwwwhindawicom Volume 2018
OptimizationJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Engineering Mathematics
International Journal of
Hindawiwwwhindawicom Volume 2018
Operations ResearchAdvances in
Journal of
Hindawiwwwhindawicom Volume 2018
Function SpacesAbstract and Applied AnalysisHindawiwwwhindawicom Volume 2018
International Journal of Mathematics and Mathematical Sciences
Hindawiwwwhindawicom Volume 2018
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
Hindawiwwwhindawicom Volume 2018Volume 2018
Numerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisAdvances inAdvances in Discrete Dynamics in
Nature and SocietyHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom
Dierential EquationsInternational Journal of
Volume 2018
Hindawiwwwhindawicom Volume 2018
Decision SciencesAdvances in
Hindawiwwwhindawicom Volume 2018
AnalysisInternational Journal of
Hindawiwwwhindawicom Volume 2018
Stochastic AnalysisInternational Journal of
Submit your manuscripts atwwwhindawicom
Hindawiwwwhindawicom Volume 2018
MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Mathematical Problems in Engineering
Applied MathematicsJournal of
Hindawiwwwhindawicom Volume 2018
Probability and StatisticsHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
Mathematical PhysicsAdvances in
Complex AnalysisJournal of
Hindawiwwwhindawicom Volume 2018
OptimizationJournal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Engineering Mathematics
International Journal of
Hindawiwwwhindawicom Volume 2018
Operations ResearchAdvances in
Journal of
Hindawiwwwhindawicom Volume 2018
Function SpacesAbstract and Applied AnalysisHindawiwwwhindawicom Volume 2018
International Journal of Mathematics and Mathematical Sciences
Hindawiwwwhindawicom Volume 2018
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
Hindawiwwwhindawicom Volume 2018Volume 2018
Numerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisNumerical AnalysisAdvances inAdvances in Discrete Dynamics in
Nature and SocietyHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom
Dierential EquationsInternational Journal of
Volume 2018
Hindawiwwwhindawicom Volume 2018
Decision SciencesAdvances in
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