Rajasthan Technical University 2010 B.Tech Mechanical Engineering Mechanical Measurements & Control (mechanical Engg.) - Question Paper
RTU Mechanical Measurements & Control (mechanical Engg.)
Rajasthan tech. University
B.tech four sem (Main/back)
Year July 2010
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B.Tech. (Sem. IV) (Main/Back) Examination, July - 2010 Mechanical Engineering 4ME6 Mechanical Measurements & Control Common for Mech. & Automobile Engg. | ||
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Time |
3 Hours] |
[Total Marks: 80 | |
[Min. Passing Marks: 24
Attempt any five questions selecting one question from each unit. All questions carry equal marks. (Schematic diagrams must be shown wherever necessary. Any data you feel missing suitably be assumed and stated clearly. Units of quantities used/calculated must be stated clearly.)
Use of following supporting material is permitted during examination. (Mentioned in form No. 205)
1. Nil__2. Nil_
1 (a) Define gauge factor of a resistance strain gauge. Show that in a wire resistance strain gauge, the value of gauge factor can be attributed to the resistance change due to changes in gauge wire length, its cross-sectional area and resistivity. Under what conditions, does the following relation hold good.
F=l+2p
Where F is the gauge factor and y is the Poisson's ratio.
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(b) Define strain. List some practical situations where strain measurement becomes essential. Can measurement of strain by applied in specialized transducers to measure certain mechanical quantities ? If so, name those relevant mechanical quantities.
8
OR
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[Contd...
Draw a block diagram representation of generalized instrumentation system. Identify the various elements and point out the function performed by each element.
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1 (a)
(b)
(c)
2 (a) (b)
(c)
2 (a)
(b)
(e)
What are Primary, Secondary and Tertiary measurement ? Explain with examples.
5
What do you mean by "Static Calibration" ? Give the steps which are necessary in performing a calibration.
6
UNIT-II
Describe piezoelectric effect. Obtain expression for voltage sensitivity of a piezoelectric crystal.
5
What are the transducers for temperature measurement ? Write the advantage and disadvantage of all of them.
5
What are thermistors ? Explain their different forms of construction. Draw their resistivity versus temperature characteristics and show that they have a very high value of sensitivity as compared with that of metal resistance thermometers. Describe their applications.
6
OR
Examine the Mechanism of a Bourdon-tube pressure gauge, and explain how the tube functions and why the curved tube tends to straighten out when pressure is applied inside ? Mention the materials used for the tube and the operating range of the particular materials.
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Explain how the operational errors of the Bourdon tubes gauge can be reduced ?
5
Explain construction and working of a thermocouple. Compare different thermocouple materials.
5
4E2054] llll III III Mill 2 [Contd...
UNIT-III
What does signal flow graph represent ? Define the various terms associated with it. List and graphically represent the different rules to simplify a given signal flow graph.
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3 (a) (b)
3 (a) (b)
(c)
4 (a)
(b)
(c)
4 (a) (b)
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Distinguish between open-loop and dosed-loop control systems with the help of a suitable diagram. Illustrate your answer using block diagram schematics. Identify the system parameters and components in each case.
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OR
How feedback can be used to reduce the effect of various spurious inputs in an instrumentation system ?
5
Explain the concept of control in engineering. List several control devices with which you are familiar and describe any two of them.
5
Define a process control system. Sketch the schematics of a shower bath which operates by a manual closed loop control arrangement. Indentify the function of each part of the system and explain how control is achieved.
6
UNIT-IV
Explain the functions of the following :
(i) AC tachometer
(ii) Potentiometer
(iii) Stepper motor.
6
What is the time response of first order systems ?
5
Make the diagram of any mechanical system and convert it into electrical analog.
5
OR
Draw the mathematical model for any thermal system.
6
Give the schematics of a general pneumatic control system and describe the functions of various elements. How the force balance controller differs from the motion balance controllers.
10
llllllllllllllllllllllHI 3 ntd...
UNIT-V
5 (a) Define system stability. Explain absolute and relative stability. List various stability criterions.
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(b) Explain absolute and relative stability of a system. Discuss Routh and Hurritz criterion for stability.
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OR
5 (a) Define system stability. Explain stable, unstable and relatively stable systems. Give salient features of Routh and Hurriz stability criterion.
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(b) Explain the concept of stability in detail. Discuss various criterions to check the stability of a system.
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