Academic Writing Subjective Assignment

1. VENKATASUBRAMANYAMURALIDHAR. P
Course: Academic Writing
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2. Measurement System:
– Definition – Basic principles of measurement – measurement systems,
– generalized configuration and functional descriptions of measuring
instruments
– examples.
– static and dynamic performance characteristics
– sources of error, classification and elimination of error.
Measurement of Displacement:
– Theory and construction of various transducers to measure displacement
– piezo electric, inductive, capacitance, resistance, ionization and photo
electric transducers, calibration procedures.
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3. Measurement
Definition:
The word measurement is used to tell us the length, the weight, the
temperature or a change in one of these physical entities of a material.
Measurement provides us with means for describing the various physical
and chemical parameters of materials in quantitative terms. For example 10
cm length of an object implies that the object is 10 times as large as 1 cm;
the unit employed in expressing length.
There are two requirements to be satisfied to get good result from the
measurement.
 The standard must be accurately known and internationally accepted.
 The apparatus and experimental procedure adopted for comparison must be
provable.
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4. Objectives of instrumentation:-
 The major objective of instrumentation is to measure and control the field
parameters to increase safety and efficiency of the process.
 To achieve good quality.
 To achieve auto machine and automatic control of process there by
reducing human.
 To maintain the operation of the plan within the design exportations and to
achieve good quantity product.
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5. Generalised measurement system and its functional elements
1. Primary sensing element.
2. Variable conversion (or) Transducer element.
3. Manipulation of element.
4. Data transmission element.
5. Data processing element.
6. Data Presentation element.
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6. Performance characteristics of a measuring instrument:-
Static characteristics
Dynamic characteristics
Static characteristics:
 Range and span
 Accuracy, error, correction
 Calibration
 Repeatability
 Reproducibility
 Precision
 Sensitivity
 Threshold
 Resolution
 Drift
 Hysteresis, Dead zone
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7. Dynamic characteristics:
 Speed of response and measuring lag
 Fidelity and dynamic errors
 Over shoot
 Dead time and dead zone
 Frequency Response
Sources of error
1. Calibration of Instrument
2. Instrument reproducibility
3. Measuring arrangement
4. Work piece
5. Environmental condition
6. Observer’s skill
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8. Classification of errors and elimination of errors:
A steady of errors is a first step in finding ways to reduce them.
Errors may arise from different sources and are usually classified as under.
◦ Gross errors
◦ Systematic (or) instrumental errors
◦ Random (or) environmental errors
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9. Measurement of Displacement
•The measurement of displacement is made frequently to relate to some other
measurement and hence displacement transducers are fundamental
components of any instrumentation system.
•Displacement is closely associated with motion (from one point to another)
and position (i.e. a change from one position to the next).
•Displacement can be measured by both mechanical and electrical methods.
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10. Transducer:
A transducer perform the following functions:
 detects or senses the changes in physical quantity being measured.
 provides a proportional output signal.
Classification of transducers:
Transducers are broadly classified into two groups as follows:
◦ Active transducers (self-generating type)
Example: Piezo-Electric crystals, Thermocouples.
◦ Passive transducers (Externally powered)
Example: LVDT, Thermistors.
Classification based on the type of output:
 Analog Transducer
 Digital Transducer
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11. According to the principle of operation, transducers for the
measurement of displacement are:
 Variable resistance transducer
 Variable inductance transducer
 Variable capacitance transducer
 Piezo electric transducer
 Photo electric or light detecting transducer
◦ Photo conductive
◦ Photo voltaic
◦ Photo emissive
 Ionization transducers
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