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NU CITMOT 601 Systems Engineering

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Title: NU CITMOT 601 Systems Engineering


1
NU CIT-MOT 601 Systems Engineering
  • Chapter 2

Systems, Life Cycle, and Approaches BRINGING
SYSTEMS INTO BEING
Benjamin S. Blanchard Walter J. Fabrycky,
"System Engineering and Analysis", 4th Ed.
Prentice Hall, 2006
2
Engineering for Product Competitiveness
  • Products must meet customer expectations
  • Systems engineering is to provide systems and
    products that meet expectations cost-effectively
  • Improved methods for defining product and system
    requirements
  • Define systems functionally before physically
  • Overall system hierarchy Interrelationships and
    Intra-relationships
  • Integration of engineering and other related
    disciplines
  • Establishing a disciplined approach with
    appropriate review, evaluation and feedback

3
Motives For Engineering Optimum Systems
  • High competition
  • Globalization
  • Ever demanding customers
  • Technology Development
  • Great strides in Science, Technology, and tools
  • Limited resources

4
The System Life Cycle Engineering
  • Acquisition phase
  • Need
  • Conceptual design
  • Detailed design
  • Production and/ or construction
  • Utilization phase
  • Delivery/ use
  • Support and improvement
  • - Phase out/ retirement/ Discard

5
1 - Conceptual Design
  • Feasibility studies are conducted to determine
    design parameters
  • Economic feasibility study
  • Market study ---- System boundaries (volume/
    quantities), price ranges, competition, life
    expectancy, capital/ funding.
  • Technical feasibility ---- resources availability
    (suppliers, capital/ funding, ..), designs,
  • Feasibility study involves
  • Needs analysis
  • Functional requirements
  • System operational requirements
  • System maintenance concept
  • Advanced product/ system planning (Plans
    Specifications)

6
2 - Preliminary Design
  • System Functional Analysis
  • Functional analysis
  • System operational functions
  • System maintenance functions
  • Preliminary Synthesis and Allocation of Design
    Criteria
  • Allocation of performance factors, design
    factors, and effectiveness requirements

7
2 - Preliminary Design
  • System Optimization
  • System and subsystem trade-offs analysis
  • Evaluation of alternatives
  • System and subsystem analysis
  • System Synthesis and Definition
  • Preliminary design, performance metrics,
    configuration and arrangement of chosen system
    (analyses, data prototyping, physical models,
    testing, etc.)
  • Detailed specification

8
3 - Detailed Design and Development
  • System-Product Design
  • Detailed design of functional system (equipment
    s/w)
  • Detailed design of system maintenance and
    logistic support elements
  • Design support functions
  • Design data and documentation
  • System analysis and evaluation
  • Design review

9
3 - Detailed Design and Development
  • System Prototype Development
  • Development of system prototype model
  • Development of system maintenance and logistic
    support requirements
  • System Prototype Test and Evaluation
  • Test preparation
  • Testing
  • Modification for corrective actions

10
4 Production and/or Construction
  • System assessment, analysis and evaluation
  • Modifications for corrective action and/or for
    product improvement

11
5 Utilization and Support
  • System assessment, analysis and evaluation
  • Continued modification for corrective action or
    for product improvement

6 Phase-out and Disposal
12
Designing For The Life Cycle
  • Considerations
  • Acquisition process
  • Standards
  • Ability to integrate
  • user compatibility
  • Serviceability/ Support
  • ...
  • For shorter Development cycle
  • Teams
  • Concurrent engineering

13
System Engineering Definitions
  • Systems Engineering
  • An interdisciplinary collaborative approach to
    derive, evolve, and verify a life cycle balanced
    system solution which satisfies customer
    expectations and meets public acceptability

14
System Engineering Definitions
  • Characteristics of Systems Engineering
  • Top-down approach that views the system as a
    whole
  • A life Cycle orientation that addresses phases of
    system life cycle
  • Initial definition of system requirements,
    relating such requirements to design evaluation
    criteria and performance measures
  • An interdisciplinary or team approach throughout
    the system design and development
  • The use of appropriate technologies and
    management principles in a synergetic manner

15
The System ProcessLife-Cycle Process and Steps
  • Phase
  • Conceptual Design
  • Preliminary Design
  • Detailed Design
  • Production
  • Operational Use
  • Baseline
  • System Specification
  • Functional allocation
  • Design/ Material/ Processes
  • Optimize
  • Open ended

Figure 2.4 pp 26
16
The System ProcessTop-Down and Bottom-Up
Approaches
  • Top-Down Approach
  • Starts from the systems functional
    requirements, (top where system input is known)
    and breaking it down into sub-functions
    identifying relationships, input, output and
    devising requirements (process) for each.
  • Bottom-Up Approach
  • Starts from the output requirement (Bottom),
    identifying what does it take for this output to
    be realized (functions, input, output), leading
    to top, where system input is determined.

17
The System ProcessTop-Down and Bottom-Up
Approaches
  • Top-Down Approach
  • Does not guarantee exactly the required
    outcome, however recognizes the need and
    limitations all along
  • Bottom-Up Approach
  • May guarantee the outcome, however, does not
    recognize limitations at the design stage, which
    require iterations.
  • Best approach is a combination of the two

18
The System ProcessFeedback In System Engineering
Process
19
The System ProcessOther System Engineering Models
Waterfall Process Model
20
The System ProcessOther System Engineering Models
Vee Process Model
21
The System ProcessOther System Engineering Models
Spiral Process Model
22
System Design Evaluation
  • At all stages, it is essential to evaluate
    alternative designs
  • To evaluate is to assess satisfying the
    requirements
  • Requirements analysis establishes the baseline
    for evaluation
  • Design criteria depends on the stage
  • Criteria are classified as
  • System level criteria
  • Sub-system level criteria
  • Components level criteria
  • ...

23
System Design Criteria - Decomposition
24
System Design Evaluation
  • The technical performance measures (TPMs)
    refelect the overall performance of the system
  • The design-dependent parameters (DDPs) are
    identified at subsystem level
  • Many factors, measures of effectiveness,
    trade-offs at all levels to be considered
  • Follow the design consideration hierarchy (Fig.
    2.9 pp 35)

25
Design Consideration Hierarchy
26
System Design Evaluation
  • An iterative, continuous process

27
Generating Evaluating Design alternatives
  • Morphology for design synthesis, analysis, and
    evaluation

28
Implementing System Engineering
  • Due to the following factors there is an
    increased trend in the use of system eng.
    Methodology
  • New technology is being introduced
  • Increased customer demands/ needs
  • Life cycles are being extended
  • Cost increase
  • Limited resources
  • ..
  • The use of strictly bottom-up approach proved
    unreliable

29
Implementing System Engineering
30
Applications of System Engineering
  • Large-scale systems with many components.
  • Small-scale systems with relatively few
    components.
  • Manufacturing systems.
  • Introduction of advanced technologies / new
    systems.
  • System that are highly equipment, software,
    facilities, or data intensive.
  • Systems having several suppliers.
  • ... etc

31
Management of System Engineering
  • System engineering is applicable in all phases of
    life cycle
  • Greatest benefits are derived from emphasis in
    early stages

32
Management of System Engineering
  • Objective is to influence the design in the early
    phases of acquisition, effectively and
    efficiently
  • It leads to the identification of the individual
    design disciplinary needs proceeding from system
    level to subsystem levels
  • Goal is to ensure that requirements are properly
    balanced and integrated
  • Applicable engineering disciplines responsible
    for the design of the individual system elements
    to be properly integrated
  • System engineering first establishes the
    requirements then ensure proper integration
    throughout the life cycle

33
Integration of Disciplines
34
Management of System Engineering
  • System engineering must be addressed in terms of
    both technology and management.
  • Concurrent Engineering
  • Communication

35
Potential Benefits of System Engineering
  • Reduction in costs along the life cycle
  • Reduction in system acquisition time
  • More visibility and less risk associated with
    design decisions
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