Post on 09-Apr-2018
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Simulation & Modeling
Kardi Teknomo, PhD
Some of the materials in this slide are my summary from Principle of System by Jay W. Forrester,Productivity, 1971
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Overview System
System Boundary
ass ca on o ys ems:
Open System
Positive feedback system
Ne ative feedback s stem
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Objective By the end of this lesson you should be
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1. System Definition: System is a grouping of
a common purpose
A system is a part of some potential reality
where we are concerned with s ace-timeeffects and causal relationship among parts ofthe system
A system may include people as well asphysical parts
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System as a black box We define a system to be a closed world
integral parts of the system from items
outside
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Example of System: Family Family is a system for living and raising
Picture source: or.ucr.edu
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Example of System: AutomobileAutomobile is a system of components
transportation
Picture Source:
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Example of System: WarehouseA warehouse and loading platform is a
Picture Source:http://www.rrii.com/images/Arlington_Warehouse_Pic.gif
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Example of System: management Management is a system of people for
activity of business
Picture source: http://www.ingres.com/images/about/group-pic-management.jpg
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Example of System: Web Web is an ecosystem
ys ems w n e we eBay
Blogosphere
Digg Flickr
MySpace
Picture source:
http://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/WorldWideWebAroundWikipedia.png/800px-WorldWideWebAroundWikipedia.png
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Discussion & Exercise
Can you find other system?
a are e componen s o e sys em What is the purpose of the system?
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2. Structure
Definition: A structure is effective
observation in any field of knowledge
Without an organizing structure,
observations, practices and conflictingincidents
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Interacting Components
Any specified behavior of a system must
interacting components.
Those components lie within a boundarythat defines and encloses the system
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Example of Structure: Physics
The law of Physics is a structure to
nature.
This structure of physical knowledge isthe foundation of todays technology
Picture source:https://reader009.{domain}/reader009/html5/0524/5b06b009e8b72/5b06b011c7d72.jpg
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Example of Structure: System Management
Management system is a structure to
psychological, industrial and economic
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Causal Thinking
Causal thinking is the key to organizing
Instead of cause, affect or influence
can be used to describe the relatedcomponents in the system
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Understand Cause & Effect
Some are logical (e.g. physics)
Money happiness
Some are not e. . sociolo economics Use of seatbelts reduced highway
fatalities
Shortened daylight hours increasedsuicide rates
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3. System Boundary
Where is the boundary, that
components, within which the dynamic
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Self-contained system
Self-Contained System: nothing flow in
Most s stem are not self-contained They function in an environmentthat
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Difficulty in defining Boundary
1. Difficult to decide at what level the
Subopmitization: decision that optimize
optimal for the system as a whole
.overlapping parts with other system
. cu o e ne e n age w eenvironment
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Closed System
In concept, a feedback system is a closed.
Its dynamic behavior arises within its
internal structure
behavior mode being investigated must
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Building Blocks
Within the system boundary the basic.
Interconnection of feedback loops form a
system
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4. Classification of System
System can be classified into
pen sys em
Feedback (closed) system
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4a. Open System
An open system is one characterized by
the outputs are isolated from and have
It is not aware of (observe and react to ) itsown performance
Its past action oes not contro uture action
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Example of Open system: Watch
A watch, taken by itself, is an open
own inccuracy and adjust itself
Picture source: https://reader009.{domain}/reader009/html5/0524/5b06b009e8b
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Example of Open System: Car
A car is an open system which by itself is
past nor does it have a goal of where to
Picture source: http://www.global-rental.com
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Discussion: open system
Can you find other open system?
xp a n w y o you n s an opensystem
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4b. Feedback System
It is also called Closed System
A feedback system has a closed loop structure
system back to control future action
Feedback system control action is influenced by theresults of its own previous action or past behavior
Its past action control present and future action
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Feedback Loop
Well conceived systems contain feedack loop.
Feedback involves monitoring the actual
behavior to standards
Information about deviation from standard is
system so that effective action can be taken
K di T k PhD
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Category of Feedback System
There are two classes of feedback
Positive feedback: growth
ega ve ee ac : goa see ng
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4b1. Positive Feedback System
Positive feedbackgenerates growth
that generate still greater action
It is in the positive feedback form ofsystem structure that one finds the forcesof growth
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Example (+) Feedback System
Bacteria multiply to produce more bacteria
are generated
Picture source:http://www.scharfphoto.com/fine_art_prints/archives/199812-053-Soil-Bacteria.
In this positive feedback system the generation
accumulated from past growth of bacteria
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4b2. Negative Feedback System
Negative feedback system seeks a goal
to achieve the goal
It is in the negative feedback, or goalseeking, structure of systems that onefinds the causes offluctuation and
instability
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Example (-) Feedback System: AC
Air conditioning system of a house is controlledb a thermostat which re onds to the heat
previously produced by the AC
Picture source:http://www.rd.com/images/tfhimport/2001/May01_Air_Conditioner_Clean/20010501_Air_Conditioner_Clean_page002img001_size2.jpg
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AC (cont)
Because the heat already produced by
generation of heat, the AC system
the goal of proper temperature
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,
Example (-) Feedback System
A watch and its owner form a negative
compared with the correct time as a goal
eliminate error
Picture source:
https://reader009.{domain}/reader009/html5/0524/5b06b009e8b72/5b06b02038
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View Point
Whether a system should be classified as an
intrinsic to the particular assembly of parts butdepend on the observers view point in definingthe purpose of the system
You can always broaden the scope and purposeof the system to change from open to feedback
system and from feedback to open system
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Review Classification of Systems
System:
pen sys em:
Past action does not control future action
r y :
Past action controls future action
Positive feedback loop
Ne ative feedback loo
Depend on observers viewpoint
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Summary
You have learned in this lesson about
ys em n ng
System definition
ystem structure
System boundary
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Discussion & Exercise: System Structure
Please select any system that interesting
Can you draw the system structure?
Specify the parts or components of
system as variables of the system Then draw arrow to connect the influence
of one art to the other art
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Discussion: Boundary
Define from your system:
ow e var a es n uence o er var a e
Is it a closed or open system?
an you in some ee ac oop
Can you draw the system boundary (to makea c ose sys em
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Discussion Points
Define from your system:
Is it open or feedback system?
How the variable influence other variable
loops
Keep your discussion for next week
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Tips
When there is a double arrow in the influence,
that have not been specified
Select variables that can be measured
uantitativel b an means
direct effect (increase or decrease). Indirecteffect indicates lack of variables in between
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Tips
Change level of details of some variables to