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Sce 503: Systems Reliability And Maintainability Question Paper

Sce 503: Systems Reliability And Maintainability

Course:Bachelor Of Science In Computer Engineering

Institution: Kenyatta University question papers

Exam Year:2008

DATE: Monday 11th August, 2008

TIME: 2.00 p.m. – 4.00 p.m.

INSTRUCTIONS
Answer question ONE and any other TWO questions.

Q1.
(a)
(i)
Explain why reliability is important in system design.
(ii)
Describe what are the quantative measures of reliability.
(b)
Define the following terms:
(i)
Operational availability
(ii)
Inherent availability
(iii)
System effectiveness
(c)
A system consists of three subsystems in parallel. The individual
subsystem reliabilities are as follows:

Subsystem A = 0.98

Subsystem B = 0.85

Subsystem C = 0.88

Determine the overall system reliability.
(d)
(i)
Explain why maintainability is important in system design.
(ii)
Describe how the maintenance requirements can be determined.

(e)
Given the following data, calculate the achieved availability,

(i)
Mct ? 5
.
0 hours
(ii)
MTBM?
(iii)
M pt ? 0
.
2 hours
(iv)
MTBs = 1000 hours

Q2.
(a)
Describe the system requirements for a system being developed in
response to fulfill some anticipated function.
(b)
Explain how the reliability of a system depends on the reliability of its
component parts selection and application.
(c)
Describe the stress-strength characteristics and explain the steps which
should be accomplished for such an analysis to be undertaken.
Q3.
(a)
Describe the quantative measures of maintainability.

(b)
Corrective maintenance task times were observed as given in Table Q3.
(i)
Determine the range of observations
(ii)

2
(iii)
Assuming 7 classes
with a class interval
of 4, plot the data, construct a curve and determine the type of
distribution indicated by the curve.
(iv)
Calculate the mean repair time
(v)
Calculate the standard deviation of the sample data.

Task time (min)
Frequency
Task time (min)
Frequency
35
2
25
12
17
6
19
10
12
2
21
12
15
4
23
13
37
1
29
8
27
10
13
3
33
3
9
1
31
6
-
-
Table Q3

Q4.
(a)
Describe the methods used in maintainability analysis that can be
effectively used in support of objectives.

(b)
(i)
Describe what is meant by maintainability allocation.
(ii)
Explain the criteria used in the selection of personnel for the
demonstration of maintenance tasks.
(c)
Explain what is meant by repair versus discard analysis.

Q5.
(a)
Describe the steps used for conducting failure mode, effects and critically
analysis (FMECA).

(b)
Describe the advantages of reliability testing.
(c)
Describe how reliability can have impact on maintainability, human
factors, supportability and cost.
……………

Sce 503: Systems Reliability And Maintainability Question Paper

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