Code No: 37094

SET 1

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JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD R05 IV B.Tech. I Semester Supplementary Exams, May/June – 2009 RELIABILITY AND SAFETY ENGINEERING (Electronics & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions. All Questions carries equal marks. -----

A can hit a target in 4 times in 5 shots; B 3 times in 4 shots; C twice in 3 shots. They fire a volley. What is the probability that two shots at least hit? [16]

2)

Explain the different mixed configurations in detail for the evaluation of Reliability.

4)

5)

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b) Failure rate d) Probability of failure

Explain the following terms: a) Operational Availability b) Inherent Availability

[8+8]

Explain the following probability distributions a) Exponential distribution b) Weibull distribution

[8+8]

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[16]

A system consist of two components A and B in series, situated such that when component is down, the other component can not fail. The failure and repair rates of the component are given below: λA=0.5/day µA=9.6/day λB=0.6/day µB=9.3/day Apply the Markov model and calculate the probability of failure of the system. [16] Explain corrective maintenance time distributions with a practical example. [16]

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6)

Explain the following terms: a) Failure density c) Mean failure rate

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Contd…2

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Write short notes on: a) Cumulative probability b) Maintainability distributions c) Time dependent probability evaluation d) Uses of reliability

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[4+4+4+4]

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8)

SET 2

Code No: 37094

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JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD R05 IV B.Tech. I Semester Supplementary Exams, May/June – 2009 RELIABILITY AND SAFETY ENGINEERING (Electronics & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions. All Questions carries equal marks. ----Explain the different probability distributions which can describe the behavior of most of the random variables encountered in practice. [16]

2.a) b)

Explain the reliability evaluation of a general series –parallel configuration. A parallel system is composed of 10 identical independent components. If the system reliability is to be 0.95,how poor can the components be? [8+8]

3)

Explain the reliability in terms of hazard rate and failure density.

[16]

4.a) b)

State and explain the fundamental assumptions of a Markov process. Explain Markov chains.

[8+8]

5)

Define maintainability distributions and explain the different types of maintainability distributions. [16]

6)

Explain reliability and maintainability trade off.

7)

Explain the terms human reliability and operator training with an example. [16]

8)

Write short notes on: a) MTTF b) MTTR& MTBF

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[16]

[8+8]

SET 3

Code No: 37094

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JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD R05 IV B.Tech. I Semester Supplementary Exams, May/June – 2009 RELIABILITY AND SAFETY ENGINEERING (Electronics & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions. All Questions carries equal marks. ----1.a) What do you mean by Binomial and Poisson distribution. b) The probability of a marksman A hitting a target is 0.8, and that of another marksman B hitting the same target is 0.7. If both marksmen A and B aim at the same target simultaneously, what is the probability of the target being hit either by A or by B? [8+8]

A system consists of 3 elements A,B and C. A and B are connected in parallel and the element C is connected in series this combination, Input is given to the combination of A and B and output is taken from C. If the reliability values of A, B and C are 0.8, 0.7 and 0.9 respectively. Determine the system reliability. [16]

3.a)

Explain with neat sketch the various regions of Bath-tub curve for failure time distribution of components Show that for exponential distribution MTTF is the reciprocal of failure rate. [8+8] Explain two state Markov process for calculation of steady state probabilities. Explain the state space method of system reliability evaluation. [8+8]

b) 4.a) b)

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2.

Explain the following terms: a) Maintainability b) Reliability c) Availability d) System down time

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6.

Explain the different steps involved in evaluation of limiting state probabilities. [16] Explain the following probability distributions [8+8] a) Uniform distribution b) Weibull distribution

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8.

Write short notes on: a) Causes of failure b) Human reliability c) Sequential addition method d) Uses of reliability.

[4+4+4+4]

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Code No: 37094

SET 4

b)

3.a)

b)

Explain the following terms : (i) Reliability (ii) MTTF (iii) MTTR (iv) MTBF A component has MTTF of 750 hours .What is its reliability for a mission time of 100 hours. [8+8] A system consists of two components A and B with independent failure and repair rates. From the state space analysis derive expressions for the steady state probability of occurrences of each state of the system. Calculate their values given λA=0.3/day µA=9.7/day λB=0.4/day µB=0.95/day [16] Explain Total productive maintenance of a system with a practical example. [16]

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4.

Distinguish with neat block diagrams parallel series and mixed parallel series systems and write down appropriate formulae in each case A manufacturing process produces parts which are one percent defective .Fifty of these parts are selected at random. What is the probability that there are two or less defective parts out of the fifty selected parts? [8+8]

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JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD R05 IV B.Tech. I Semester Supplementary Exams, May/June – 2009 RELIABILITY AND SAFETY ENGINEERING (Electronics & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions. All Questions carries equal marks. ----1.a) Explain briefly about negative binomial distribution. b) A small village, which has no permanent medical facility in the form of a hospital or a health center, is served by three mobile units coming from three centers A, B, and C. These mobile units also serve many other villages in the region. The mobile units pass through the village several times in a day and they appear on the average equally frequently. What is the probability that a waiting patient will be served by the unit coming from center B? [8+8]

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6.

Explain different types of system reliability improvement methods with examples. [16] Contd…2

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8) Write short notes on: a) Product safety improvement program b) Product reliability

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7) Explain the following probability distributions a) Uniform distribution b) Binomial distribution c) Normal distribution d) Geometric distribution

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