CS672 – System Engineering and Analysis Discussion 6 - 11/9/2018 Samson Kamal Victor Chapter 12, Question 1: Reliability: Reliability is an ability of software to run with minimum number of failure rate in the given period of time. The software failure may be some errors, uncertainty, and misinterpretation of initial system requirement. Software faults are the design faults of the system (Jiantao, 1999) Characteristics: · Design faults cause · Errors may occur without warnings · Restart in certain time period will reduce the failure · Reliability of prediction is depend on the human design · Software interfaces are not visual or physical it is only conceptual · Software reliability is not operational time dependence but depend on number of successful operations · Based on the number of failure rate to predict the future system · Proper well designed framework can lead more reliable software Chapter 12, Question 2: System design: The reliability in system design is very important to predict of failure, quantitative and qualitative reliability requirement of mean time between failure (MTBF) and meantime between maintenance (MTBM) The reliability need to be checked in each stage of the lifecycle. In the conceptual design stage, preliminary design, detail design and development, production, operation and support. Complete weaved in development cycle To extend the reliability in the system design then in the conceptual design stage must be done in detailed with the reliability requirements. If the reliability is analyzed properly then it would product may work for extend period of life time. The reliability analyses, evaluation prediction and the formal design review and approval Chapter 12, Question 3: Quantitative measure of reliability: Understanding the nature of system thoroughly and the product metric help to measure the quantitative measure of software reliability. The size of the product can be measured using the line of code (LOC), also using the source line of code (SLOC) and thousand source line of code (KSLOC) with no comments, allows to understand the functionality and complexity of the code, the flow chart diagram will show simplified representation of code, testing of the code functionality and estimate the fault will make the product more reliable (Jiantao, 1999) The quantitative measure of personal reliability can be measured based on the three factors over time (test-retest reliability) the intelligence of the personal in consistent across time. Internal consistency is represents the self esteem or good qualities of the personal and interact reliability of social skills and how they interaction with others (ReliabilityMeasurement, 2015) The hardware system is physical device like sensor, controllers and actuators. The hardware reliability is required of time related model to check the physical device fail over time to avoid the physical faults The quantitative measure of data reliability supported by the positivis.

1. CS672 – System Engineering and Analysis
Discussion 6 - 11/9/2018
Samson Kamal Victor
Chapter 12, Question 1:
Reliability:
Reliability is an ability of software to run with minimum
number of failure rate in the given period of time. The software
failure may be some errors, uncertainty, and misinterpretation
of initial system requirement. Software faults are the design
faults of the system (Jiantao, 1999)
Characteristics:
· Design faults cause
· Errors may occur without warnings
· Restart in certain time period will reduce the failure
· Reliability of prediction is depend on the human design
· Software interfaces are not visual or physical it is only
conceptual
· Software reliability is not operational time dependence but
depend on number of successful operations
· Based on the number of failure rate to predict the future
system
· Proper well designed framework can lead more reliable
software
Chapter 12, Question 2:
System design:
The reliability in system design is very important to
predict of failure, quantitative and qualitative reliability
requirement of mean time between failure (MTBF) and
meantime between maintenance (MTBM)
The reliability need to be checked in each stage of the
lifecycle. In the conceptual design stage, preliminary design,
detail design and development, production, operation and

2. support. Complete weaved in development cycle
To extend the reliability in the system design then in the
conceptual design stage must be done in detailed with the
reliability requirements. If the reliability is analyzed properly
then it would product may work for extend period of life time.
The reliability analyses, evaluation prediction and the formal
design review and approval
Chapter 12, Question 3:
Quantitative measure of reliability:
Understanding the nature of system thoroughly and the
product metric help to measure the quantitative measure of
software reliability. The size of the product can be measured
using the line of code (LOC), also using the source line of code
(SLOC) and thousand source line of code (KSLOC) with no
comments, allows to understand the functionality and
complexity of the code, the flow chart diagram will show
simplified representation of code, testing of the code
functionality and estimate the fault will make the product more
reliable (Jiantao, 1999)
The quantitative measure of personal reliability can be
measured based on the three factors over time (test-retest
reliability) the intelligence of the personal in consistent across
time. Internal consistency is represents the self esteem or good
qualities of the personal and interact reliability of social skills
and how they interaction with others (ReliabilityMeasurement,
2015)
The hardware system is physical device like sensor, controllers
and actuators. The hardware reliability is required of time
related model to check the physical device fail over time to
avoid the physical faults
The quantitative measure of data reliability supported by the
positivist or scientific paradigm that up of observable,
measurable facts
Chapter 12, Question 4:

3. Failure rate:
The failure rate is necessary to be identified in the systems
engineering to define the products usability duration. It is a
mean value and probability of number of failure and total
number of hours
Failure rate (λ) = number of failures / total operating hours
The mean time between failure (MTBF) provide the guidance
for the system to minimize failures in the high quality system 1/
λ (David, n.d.)
Chapter 12, Question 24:
Sequential reliability testing:
Advantage: allow very low failure rates and doesn’t not allow
very high failure rates in shorter time. Less testing time
(GoogleBooks, n.d. Page. 301)
Disadvantage: The total test duration is undetermined and for
the maximum duration must be planned before (GoogleBooks,
n.d. Page. 301)
Failure mode effect and critical analysis (FMECA):
It is a bottom up approach to find the top level failure in the
system. The top events cannot be identified by externally. The
FMECA primary goal is to determine all the possible failure
modes. It requires the intervention of both human and software
(Murray, 2009)
Fault tree analysis (FTA):
It is a top down approach to find the lowest level failure in the
system. FTA is a easiest and faster way of identifying the
failure modes in the system and provide more focus on the
engineering minds. It uses the graphical block diagram to
visualize the failures (Murray, 2009)
Chapter 13, Question 1:
Maintainability:
Maintainability is a measure done at the stage of designing the
system with the fact of down time required for the product,

4. software development lifecycle cost, and support cost.
Maintenance is the process of doing the action to solve the issue
or problem occurred to maintain the system to run properly in
regular basics for example: fault tree, optimize reliability
allocation, cluster storage (Davood, 2016)
Chapter 13, Question 2:
System design for maintainability:
The importance of maintainability in system design is to reduce
the costs involved in the building system design, safety,
accuracy, maintenance within the system to improve the
effectiveness and efficiency of maintenance. To design the
maintainability the knowledge of operation and maintenance is
must
The maintainability is done throughout system lifecycle like
conceptual design phase to define all the necessary need for the
system to run smooth and less maintenance cost, acquisition
phase of well planned in requirement stage, operation and
maintenance phase to monitoring and provide the system
support and disposal phase logistics to ship the products
(Davood, 2016)
Chapter 13, Question 3:
Quantitative measure of maintainability:
The measure of the maintainability must ensure that all the
needs mentioned in the design phase are satisfied and all done
by the quantitative measure. All the system need to consider the
required parameter to measure. These parameters include mean
time to repair (MTR), mean time between failures (MTBF), and
scheduled maintenance frequencies factor (MFF), Maintenance
labor hour (MLH) maintenance man-hours per operating hour
and fault detection and isolation, and Maintenance elapsed time
factor (METF)
Chapter 13, Question 4:
Mean time between failures (MTBF) represents the reliability

5. measure of system and average failure of the system to operate
in the total uptime (Adman, 2017)
MTBF = 1 / (number of failures / total operating hours)
Mean time between maintenance (MTBM) represents the
maintenance hours between the another maintenance time to
analyze the only the maintenance activity, maintenance can be
scheduled or unscheduled
MTBM = 1 / (1/MTBM + 1/MTBM)
Mean tie between repairs (MTBR) represents the total repair
time in hours. To understand the number of hour of failure in
the system only for repair
MTBR = Total repair time / number of repair
Chapter 13, Question 21:
FMECA and RCM analysis:
Reliability centered maintenance (RCM) is systematic process
the involved to develop the effectiveness, economy, focused and
maintenance and other plans for the system. The main technique
is the system check for the previous system process used for
design, development and implementation and risk involved. The
same would be carried out for evaluation of preventive
maintenance in new system
The FMECA is the part of RCM process after adding the step
five failure consequences then step one to four makes up the
FMECA. The FMECA take the preventive measure from the
RCM to justify the information of the system is reliable further
or not, thus the RCM is integrate in the FMECA tools
References:
Adman K, (Jan 30 2017), “MTBF, MTTR & MTBM, Reliability
metrics” https://www.linkedin.com/pulse/mtbf-mttr-mtbm-
reliablility-metrics-mohamed-izzaldin-ahmed
David, (n.d.), “How to Calculate Failure Rates.”,
https://sciencing.com/calculate-failure-rates-6403358.html
Davood M, (Jan 27 2016), “Maintainability Engineering”,
https://www.linkedin.com/pulse/maintainability-engineering-

6. davood-mosaddar
Davood M, (Jan 27 2016), “Reliability and Maintainability
Management Tasks in System Life Cycle”,
https://www.linkedin.com/pulse/reliability-maintainability-
management-tasks-system-life-mosaddar
GoogleBooks, (n.d.), “Reliability of Software Intensive
Systems.”,
https://books.google.com/books/about/Reliability_of_Software_
Intensive_System.html?id=BONKLjwV7AoC
Jiantao P, (1999), “Software Reliability”,
https://users.ece.cmu.edu/~koopman/des_s99/sw_reliability/
Murray S, (Sep 1 2009), “FMECA or FTA?”
https://opsalacarte.com/fmeca-or-fta/
ReliabilityMeasurement, (Oct 13 2015), “Reliability and
Validity of Measurement”
https://opentextbc.ca/researchmethods/chapter/reliability-and-
validity-of-measurement/
Why Geography Matters
Discussion Points Template
Name: __________________________________
Chapter #: ____________
Directions: Use this form to prepare key points from the text for
in-class discussion. Under the analysis sections, include your
own thoughts and interpretations, why the quote or key point is
important, connections to other parts of the text or your own
experiences, etc. Also, be sure to cite any and all essential
elements or geographic concepts that apply as you discuss them.
Finally, include a key geographic understanding—or
takeaway—that you gleaned from the chapter, explaining the
connection to the geography and why it resonated with you.
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7. Analysis:
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Analysis:
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Analysis:
Chapter Key Geographic Understanding: