reliability HW
aathai
HomeworkonCh11Reliability.docx30 points
1. (5 points) A transistor has an exponential time to failure rate of 0.00005 per hour. Find its reliability for 5000 hours. If the time to repair is also exponential with rate 0.006 per hour. What is its availability?
2. (5 points) A remote control has 30 components in series. Each has a reliability of 0.995. What is the reliability of the remote? Suppose that each component is replaced by a set of two components in parallel. What is the reliability of the new design?
3. (5 points) Four components A,B,C,and D are parallel in a subsystem and the respective reliabilities are: 0.98, 0.96, 0.94 and 0.99. What s the reliability of the subsystem?
4. (15 points)
D
A
A
A
C
B
F
F
E
|
Component |
Reliability (fixed) |
Time to failure rate per hour (exponential distn) |
|
A |
0.90 |
0.0004 |
|
B |
0.95 |
0.00005 |
|
C |
0.97 |
0.0003 |
|
D |
0.93 |
0.0007 |
|
E |
0.91 |
0.0007 |
|
F |
0.95 |
0.00035 |
a. Find the reliability of the above system using the fixed reliability model.
b. Find the MTTF of the above system using exponential distribution assumption (data in column 3). (For subsystems with parallel components, find the mean time to failure and then calculate the failure rate.) I=Once you establish the MTTF for the two subsystems and calculated the rate you can find the overall rate with series systems. What is the probability that he system will run for 2000 hours?
