Date post: | 05-Apr-2018 |
Category: |
Documents |
Upload: | tahir-yamin |
View: | 217 times |
Download: | 0 times |
of 29
7/31/2019 Instrumentation WK -1
1/29
Dr. Shafiq R. Qureshi
PhD ( University of Manchester)
Engineering Sciences Department
ME-831: Instrumentations, Measurement& DAQ Systems
7/31/2019 Instrumentation WK -1
2/29
Course Overview
Basic theory of Instrumentation and Experimentation
Computer based Data Acquisition - theoretical concepts
LABVIEW Programming and data acquisition
Process instrumentation
Assignments based on self study and presentations
LABVIEW Project
Quiz Assignment and Tests as per NUST Statue
7/31/2019 Instrumentation WK -1
3/29
Books
Figliola, R.S. & Beasley, D.E., Theory & Design for Mechanical Measurements , J. Wiley & Sons, Inc. Availablein Library
Patrick F. Dunn, Measurement and Data analysis forengineering and science
Available in Library
Fundamentals of Instrumentation and Measurement editedby Dominique Placko
EBook Available
7/31/2019 Instrumentation WK -1
4/29
Instrumentation comprises scientific activities and technologies thatare related to measurement. It is a link between physical, chemicaland biological phenomena and their perception by humans.
Measurement is the basis of scientific and industrial research. Itallows us to understand the phenomena we observe in ourenvironment by means of experimental deduction and verification
Measurement therefore brings together knowledge andtechnological progress.Universal and essential to many disciplines, it is, in fact,fundamental to most human activity.
INSTRUMENTATION AND MEASUREMENTS
7/31/2019 Instrumentation WK -1
5/29
Terminologies
Measurement, Instrumentation and Metrology
The expression of measurement needs or tests are an everydayoccurrence in science and industry. All existing tools that help uscarry out measurement are part of instrumentation. Rules for usingand guaranteeing measurement created metrology. It is importantto point out that definitions of these related terms are sometimes
confused, as with measure and metrology.
The word measurement has many meanings. The InternationalVocabulary of Basic and General Terms in Metrology (VIM), usingInternational Organization for Standardization (ISO) norms, has
defined measurement as:a set of operations having the object of determining the value of aquantity
In other words, a measurement is the evaluation of a quantitymade aftercomparing it to a quantity of the same type which we use as aunit.
7/31/2019 Instrumentation WK -1
6/29
7/31/2019 Instrumentation WK -1
7/29
Fig 1 Control and measurement system
7/31/2019 Instrumentation WK -1
8/29
Metrology, the science and grammar of measurement isdefined as the field of knowledge concerned withmeasurement.
Metrology
It guarantees the meaning and validity of measurement by strictaccordance to established units. These units are standardized
on national and international levels.Metrology plays a role in international agreements joiningnational systems of measurement to those used in othercountries, making conversion between systems possible.
Standardized measurement units mean that scientific andeconomic figures can be understood, reproduced, and convertedwith a high degree of certitude.
Example : The International Bureau of Weights and Measuresbased in France is an international authority in charge of
establishing international metrological rules.
7/31/2019 Instrumentation WK -1
9/29
In scientific research, interactions between experimentsand theories are permanent. Therefore, establishing acomparative relation between a quantity to be evaluated
and a reference quantity or standard by means of aninstrument of measurement is an interaction betweeninstrumentation and metrology that guarantees thereliability of obtained results.
7/31/2019 Instrumentation WK -1
10/29
Experiments Need - Why do we need Experiments ?
Some quotes
Experiments are basis of all theoretical predictions, withoutexperiments there would be no results, and without anytangible data, there is no basis for any scientists orengineer to formulate a theory.
The advancements of culture, civilization depend uponexperiments which bring about new technology.
Making predictions can serve as a guide to what we expect,but to really learn and know what happens in reality,experiment must be done.
7/31/2019 Instrumentation WK -1
11/29
7/31/2019 Instrumentation WK -1
12/29
The interplay betweenexperiment and theory.
In scientific method experiments are done in a systematic and
rigorous manner, with the goal of arriving at a broader theoreticalunderstanding. Using the approach the results of positiveexperiments and observations are gathered and considered.
A preliminary hypothesis is formed. All rival hypotheses are testedfor possible
validity. Hopefully, only one correct hypothesis remains
7/31/2019 Instrumentation WK -1
13/29
Science and Experiment There are two goals of science: Explanation and understanding,
Prediction and control.
Its modern basis is the experimental method of proof.
Explanation and understanding encompass statements that makecausal connections.One example statement is that an increase in the temperature of aperfect gas under constant volume causes an increase in its pressure.
These usually lead to an algorithm or law that relates the variablesinvolved in the process under investigation.
Prediction and control establish correlations between variables. Foraboves example, these would result in the correlation betweenpressure and temperature.
7/31/2019 Instrumentation WK -1
14/29
ExperimentsAn Experiment is an act in which one physically intervenes withthe process under investigation and records the results.
Traditionally theory explains existing results and predicts newresults; experiments validate existing theory and gather resultsfor refining theory
Some terminologies
Variables: Independent , Dependent and
extraneousAn experiment manipulates record effect on .Variable which
cannot be controlled
Controlled Experiment : in which all variable are identified andcontrolledIn reality all experiments have some extraneous variable and
Inability to precisely control every variable is the primarysource of a experimental uncertainty.
7/31/2019 Instrumentation WK -1
15/29
Parameter : A variable that is either actively or passivelyfixed through out the experiment is called a parameter. i.e. Re in flow measurement
Classification of Experiments:
Variational : Establishes the mathematical relationship
between experiments variable. Ideal &imperfect
Validational : To validate a specific hypothesis Galilean experiment
Pedagogical : To teach the novice or demonstrate
Explorational: to explore the idea or possibility
Discovery : discovery of bacterial repression by penicillin
7/31/2019 Instrumentation WK -1
16/29
Experimental Test Plan
Parameter Design Plan:
Test objective and identification of process variables and amean for their control.
System and Tolerance Design Plan:
This is selection a selection of a measurement technique,equipment and test procedure based on some preconceivedtolerance limit for error.
Data reduction Design plan:
Plan ahead how to analyze, present and use the anticipateddata
7/31/2019 Instrumentation WK -1
17/29
Review different unit system at your own
Identify and understand seven fundamental dimension in SI and Technical English System
Conversion between both system
A quiz will follow next week
What is Significant Figure ?
It has something to do with precision of result ?
Most Significant, Least significant
7/31/2019 Instrumentation WK -1
18/29
Definitions of Common Terms1. Readability of an InstrumentCloseness with which the scale of an instrument could be read
An instrument with a 12-in scale would have a higher readability than aninstrument with a 6-in scale and the same range.
2. Least CountSmallest difference between two indications that can be detected on theinstrument scale.
3. Sensitivity Analog InstrumentRatio of linear/angular movement of the pointer to the change in the measured
variable causing this movement.e.g., a 1mV recorder might have a 25cm scale length. Its sensitivity would be25cm/mV
7/31/2019 Instrumentation WK -1
19/29
Definitions of Common Terms4. HysteresisAn instrument is said to exhibit hysteresis when there is a difference in readingsdepending on whether the value of the measured quantity is approached fromabove or below.
5. AccuracyIndicates the deviation of the reading from a known input.
6. PrecisionIndicates the ability of an instrument to reproduce a certain reading with a givenaccuracy.
Hysteresis may be the result of mechanical friction, magnetic effects, elasticdeformation, or thermal effects
7/31/2019 Instrumentation WK -1
20/29
CalibrationIt is very important to reduce the errors in accuracy
Calibration MethodsCalibration procedures involve a comparison of the particular instrument witheither:
1. A primary standard
2. A secondary standard with a higher accuracy than the instrument tocalibrated3. A known input source
StandardsNIST maintains the standards in US
L: 1982 definition: 1m is the distance light travels in 1/299,792,458ths of a secon T: 1967 definition: The Thirteenth General Conference on Weights and Measures
adopted a definition of the second as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levelsof the fundamental state of the atom of cesium-133. The estimated accuracyof this standard is 2 parts in 10 9 .
M: Defined in terms of a platinum-iridium mass maintained at Int. Bureau of Weights and Measures
V: 1990 definition: Related to Josephson effect which occurs at liquid heliutemperatures: Based on Quantum Hall Effect
Temperature: An absolute temperature scale was proposed by LordKelvin in 1854
7/31/2019 Instrumentation WK -1
21/29
Standards
7/31/2019 Instrumentation WK -1
22/29
Standards
7/31/2019 Instrumentation WK -1
23/29
Standards
7/31/2019 Instrumentation WK -1
24/29
Standards
7/31/2019 Instrumentation WK -1
25/29
Assignment
Book: Theory and Design for MechanicalMeasurements
Chapter 8 Temperature measurementChapter 9 Pressure and velocity MeasurementChapter 10 Flow MeasurementChapter 11 Strain Measurement
Chapter 12 Metrology, Motion Force and PowerMeasurement
7/31/2019 Instrumentation WK -1
26/29
Fluid Mechanical VariablesMeasurement
Pressure MeasurementBarometers and barographsBourdon tubes, Vidie capsules, MEMS
diaphragmsSound Pressure/Level Measurement
Human ear responseMicrophones
Moving coil
QuartzPiezoelectricElectretCapacitance
7/31/2019 Instrumentation WK -1
27/29
Flow Measurement
Differential Pressure Flow meters Variable Area Flow meters Positive Displacement Flow meters Turbine and Vane Flow meters Impeller Flow meters Electromagnetic Flow meters Ultrasonic Flow meters
Vortex Shedding Flow meters Thermal Mass Flow meters Carioles Effect Mass Flow meters Drag Force Flow meters
7/31/2019 Instrumentation WK -1
28/29
Point Velocity Measurement Pitot Probe Anemometry Thermal Anemometry Laser Anemometry
Viscosity MeasurementSurface Tension Measurement
Thermal Conductivity Measurement Heat Flux Measurement Calorimetry (e.g. differentialscanning calorimeter (DSC)) Thermal Imaging
7/31/2019 Instrumentation WK -1
29/29
Temperature MeasurementSolid differential thermal expansion (e.g.bimetallic strips)Liquid expansion (e.g. glass bulb-capillary)
Gas/vapor expansion (e.g. refrigeratorsensor)Resistivity change (e.g. platinumresistance (RDT))
Thermocouples (e.g. Type K and J)
ThermistorsSemiconductor diodesInfrared sensorsPyroelectric sensors
Temperature indicating materials (e.g.battery tester strip)Resonating crystal sensors (e g quartz
Thermal Variables Measurement