Chapter 3 From Chapter 2 we had these

1
Chapter 3 From Chapter 2 we had these steps
in the SE process

• Problem definition
• Consumer need
• Feasibility
• System operational requirements
• Maintenance and support concepts
• Determine/prioritize TPMs

• Functional analysis
• Requirements allocation
• System synthesis
• Design integration
• TE
• Production
• Operational use
• Retirement

2
Chapter 3
From SE Fundamentals
3
Chapter 3

• Notice how the steps on previous slide map into
  Fig 3.1 and Fig 1.12.
• In Fig 3.2 the MIL-STD-490 terms are used.
• Type A, B etc.
• Names arent important the ideas of flowdown and
  increasing design detail are!
• Well use the 490 terminology but understand
  the meaning behind the type.

4
Chapter 3

• Type A (system spec) - usually only 1.
• Technical, performance, operational and support
  characteristics of the system as whole.
• Feasibility,operational requirements, functional
  analysis products go here.
• Defines subsystems.
• Has a Section 4!

5
Chapter 3

• Type B (development spec) - usually several.
• Technical, performance, operational and support
  characteristics of specific subsystems.
• Performance, effectiveness, and support
  characteristics are included.
• Defines assemblies or CSCIs.
• Has a Section 4!

6
Chapter 3

• Type C (product spec) - usually many.
• Design details.
• Hardware separate from software.
• Has a Section 4!
• Type D and E
• Specific process and material requirements.

7
Chapter 3
From SE Fundamentals
8
Chapter 3

• The requirement allocation process selects
  assignments of specific allocated requirements to
  specific specifications.
• See Fig 3.3 for an example of a spec tree.
• Order of precedence is important!

9
Chapter 3
From SE Fundamentals
10
Chapter 3
From SE Fundamentals
11
Chapter 3

• See Fig 3.4.
• Type A,
• TPMs usually here.
• These are the typically used sections.
• The essence is the important part but, using this
  format is comfortable within DOD.
• Types B, C etc are typically laid-out the same.
• Next page from SEF Guide.

12
Chapter 3
From SE Fundamentals
13
Chapter 3
From SE Fundamentals
14
Chapter 3
Blanchard selects 12 design disciplines for
further discussion because they have been
historically inadequately integrated into system
developments and mainstream design effort. They
are

• software development
• reliability
• maintainability
• human factors
• safety
• security

• producibility
• logistics
• disposability
• quality
• environmental
• value/cost

Well discuss them briefly, be sure to be aware
of the existence of them all and the type of
engineering they accomplish!
15
Chapter 3

• Software engineering things to know
• Same processes and flow in the system engineering
  of software as hardware.
• Software engineers may have their own special
  names but they are equivalent.
• Testing subroutines, subprograms and integration
  into programs flows in a similar fashion as
  hardware.

16
Chapter 3

• Software engineering things to know
• Verification can include evaluating the
  consequences of every data path regardless of
  its use likelihood.
• Stress testing explores the limits of i/o,
  throughput and processing.
• Software QC deals with subjects like - were the
  standards followed?
• Following three charts are examples of software
  development methodologies...

17
Structured Analysis, Structured Design
18
Test Planning
Certification 1
Certification 2
Certification 3
19
Object Oriented Design

• Effort
• Implementation
• Detailed Design
• Broad Design
• Software requirements
• Requirements analysis
• Time

Basic Classes
Specific Classes
I disagree with the authors note 12 page 127.
Objects are determined by the functional flowdown.
20
Chapter 3

• Reliability Engineering things to know
• Probability based.
• Item is considered reliable if the mission of the
  device is accomplished.
• Implies a component may fail its mission while
  the system may not fail its mission and vice
  versa
• R, MTBF and ? are important parameters.
• R e-t? where t operating time and ? average
  failure rate.
• e-t? represents the probability of zero failures
  in t.

21
Chapter 3

• Reliability Engineering things to know
• Look at the typical failure curves in Fig 3.8.
• Whats the difference between a software failure
  and a hardware failure?
• Note the effects of redundancy on reliability in
  Fig 3.11.
• In Fig 3.14 items 1-5 are for SEs, and 17-20 for
  testers (also SEs).

22
Chapter 3

• Reliability Engineering things to know
• Importance of FRACAS!
• Suggest an automated problem identification and
  notification system!
• Anyone who suspects a problem documents it and
  then it gets dispositioned (i.e. reviewed and
  actions assigned to correct as required).
• Lets look at the reliability qualification
  testing paragraph page 142, para7
• Notice the synergism that can/should occur
• Results in time and savings

23
Chapter 3

• Maintainability Engineering things to know
• Maintainability is the ability of an item to be
  maintained.
• Maintenance is the action to restore or retain a
  specified operating condition.
• See the time relationships in Fig 3.17.
• A log-normal distribution is typical of
  maintenance times. See Fig 3.18.

24
Chapter 3

• Maintainability Engineering things to know
• See Fig 3.19. How many were false alarms?
• Availability is the factor of interest to your
  customer.
• A? MTBM/(MTBM MDT)
• If one has or anticipates low A? whats the fix?
• Lots of units, Lots of spares, Lots of
  maintenance personnel, Lots of !
• Maintainability demonstrations are valuable but
  extremely expensive (See page 156)
• Look for alternative ways to get the data.

25
Chapter 3

• Human factors engineering things to know
• Human as a part of the system!
• Called ergonomics, considers
• Size (page 159).
• Senses.
• Physiological factors.
• Psychological factors.
• Interface called MMI.
• This interface requires as much or more
  definition as machine to machine. This can be a
  big time consumer.

26
Chapter 3

• Human factors engineering things to know
• Mockups and simulators likely required during
  design.
• Human subjects typical of end user (I.Q.,
  training, etc.) needed as test subjects during
  design.
• See Fig 3.26 for tasks especially 15- testing.

27
Chapter 3

• Safety engineering things to know
• This is not about conducting a test safely.
• This is about designing a system to minimize
  human and hardware/software exposure to unsafe
  conditions.
• When a hazard cant be eliminated then safety
  engineering determines a safe (acceptable risk)
  way to deal with it.

28
Chapter 3

• Safety engineering things to know
• Notice how many of the ilities come together
  synergistically (integrated by the SEMP) to
  support safety.
• Paragraph 1 section 3.4.5 page 167.

29
Chapter 3

• Security engineering things to know
• Prevents planned introduction of faults/failures.
• Similar to preventing inadvertent faults by
  careless operators except for intent.
• Includes encryption techniques and devices.
• Virus detectors and physical access barriers are
  examples.

30
Chapter 3

• Producibility engineering things to know
• Objective is to convert the results of RD
  efforts into something that can be produced
  outside the lab.
• Minimize the following

• critical materials
• critical processes
• proprietary items
• special production tooling

• unrealistic tolerances
• special test systems
• highly skilled personnel
• production/procurement lead times

31
Chapter 3

• Logistics engineering things to know
• Figure 3.32 is a good summary of the elements of
  logistics.
• Figure 3.33 shows when engineering can influence
  the design to reduce risk and costs.
• Logistics is an area with tremendous lifetime
  costs !
• OTE is the typical place for evaluation of the
  logistics stream.

32
Chapter 3

• Quality engineering things to know
• QC and QA are after the fact i.e. checking the
  final product.
• TQM and QFD are from the beginning.
• Emphasis on the following
• Customer satisfaction no satisfaction no
  quality.
• Continuous improvement.
• Variability minimization (6 sigma).
• Everyone (not just an inspector) involved.

33
Chapter 3

• Environmental engineering things to know
• Ecological, political and social factors.
• Affects test choices e.g.
• Bombing range in Puerto Rico.
• Sonar test impact on whales.
• Use and retirement issues.
• Lithium batteries in airplanes.
• Nuclear leftovers like old submarine reactors
  -where do you dispose of them?

34
Chapter 3

• Value/Cost engineering things to know
• See top of page 188 for examples of figures of
  merit.
• From a functional flow diagram, estimate the
  costs of the various functions from beginning to
  end.
• Lots of models exist.
• Appendix B provides details and examples.
• LCC analysis may justify expensive testing.