52115-mt----reliability Engineering

NR

Code No: 52115/MT M.Tech. – I Semester Supplementary Examinations, September, 2008 RELIABILITY ENGINEERING (Electrical Power Systems) Time: 3hours

Max. Marks:60 Answer any FIVE questions All questions carry equal marks ---

1.a) b) c)

Distinguish between pdf and PDF with a suitable example. Discuss about the two parameter probability distribution functions which is dependent on the mean and standard deviation of a random variable. Define probability density functions of a binomial distribution by deriving necessary expressions.

2.a) b) c)

Discuss about the hazard rate curve for components. Develop the relationship between MTTF and reliability function. Classify the types of failures and discuss.

3.a)

For the reliability logic diagrams shown in figure.1a and figure. 1b find the symbolic reliability, expression and hence obtain the reliability index of the system if each component has a probability of failure of 0.61.

Figure.1a b)

Figure.1b

The reliability logic diagram of the system is shown in figure.2 Develop the symbolic reliability expressions if out of the components 3,4,5,6 atleast two must function for the systems success.

Contd…2.,

Code No: 52115/MT

4.a) b)

::2::

Figure.2 Develop the expressions for unreliability of a non-series-parallel systems using failure modes of a system, considering suitable example. For the following network shown in figure.3, develop symbolic unreliability expression using network partitioning approach.

Figure.3 5.a) b)

Define STPM and develop the recursive relation to compute STPM at any interval for components with discrete Markov model. For the following state space diagrams shown in figure.4, obtain the limiting state probabilities. If now state 2, is considered as absorbing state, find the number of time intervals that would have been spent in each state before reaching to the absorbing state.

Figure .4

Contd…3.,

Code No: 52115/MT

6.a) b)

7.a) b) 8.

::3::

Develop expressions for time dependent probability of one component repairable systems. Develop the expressions for Limiting state probabilities of a two component repairable systems with identical capacities and identical transitional rates. Develop the expressions for basic probability indices of a system in which all the components must function for the system success. Develop the models and STPMs of a two component repairable model whose failures are due to common cause. Write short notes on: a) Weibull distribution b) Path based approach for network reliability evaluations c) Basic probability indices for parallel systems.

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