Punjab Technical University 2005 M.Tech Electronics and Communication Engineering RELIABILITY OF ELECTRONICS & COMMUNICATION SYSTEMS ECE 511/512 - Question Paper

RELIABILITY OF ELECTRONICS & COMMUNICATION SYSTEMS ECE 511/512 2nd/3rd Sem May 2k5

Max marks 100

Note: Attempt any 5 ques.. All ques. carry equal marks.

1. Explain failure rate and bath tub failure curve. Derive the relationship ranging from failure rate and failure probability density function. Consider the probability density function
(please see the attachment)
t is in hours. compute reliability function, failure times if design life reliability of 0.95 is desired.

2. (a) elaborate the different sources to collect failure data? In how many ways the failure data can be classified?
(b) A microwave transmitter has exhibited a constant failure rate of 0.00034 failure per operating hour, which provide non-acceptable design life (0.95 reliability) of 150 hours. A 2nd redundant transmitter is added in parallel. What is design life of new system? What is failure rate and hazard rate function of this redundant system?

3. (a) Write a short note on Monte-Carlo method of reliability simulation.
(b) provided a Weibull distribution (failure) with a shape parameter of 0.33 and a scale parameter of 16,000. Characterize the reliability parameters. Show that 10 hours burn in period will increase the design life of component (reliability 0.90).

4. (a) Derive the overall reliability and constant failure rate of n components connected in:
(i) series
(ii) parallel
(b) A radio set consists of 3 major components: a power supply, a receiver and an amplifier having reliabilities of 0.8, 0.9 and 0.5 respectively. calculate system reliabilities for both high level and low level redundancy systems with parallel components.

5. (a) discuss the difference ranging from the dormant mode failures and immediate mode failures in redundant system with imperfect switching.
(b) 3 identical transmitters are available every having a constant failure rate of 0.0035 per operating hour. A mission requires 500 hr of continuous transmission. Determine the reliability of the system.

6. (a) elaborate the different factors affecting maintainability of a system? explain the different measure of maintainability.
(b) A compressor has Weibull failure process with beta =2 and theta = 100 days. If we presume a 20 days, preventive maintenance program (T=20), show that preventive program is improving the system performance.

7. (a) describe availability, .Intrinsic availability, equipment availability and generalized operational availability.
(b) a component has MTBF = 300 hr and MTTR = 15 hr with both the failure and repair distribution exponential. What is the availability at 10 hr, for 1st 10 hr and at steady state?

8. write short notes on the following:
(a) Reliability and Safety
(b) Reliability Management

Earning:   Approval pending.