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System Effectiveness
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System Design Issues
System Design IssuesSystem Design Issues•Product, process, and support life-cycles
System EffectivenessSystem Effectiveness
Design Iteration with System-Design Iteration with System-Level EvaluationLevel Evaluation
• Design processes should ideally consider multiple parameterso Life-cycleo Various technical performance measures
• Potential benefitso Allows trade-offso Correct design problems earlyo More effective designs
• Methodso Concurrent engineeringo Life-cycle engineering
Cont..
Design Iteration with System-Design Iteration with System-Level EvaluationLevel Evaluation
Simple Cost AnalysisSimple Cost Analysis
• System life-cycle costs are a function ofo Design-dependent parameters, e.g. total cost for componentso Design-independent parameters, e.g. labor costs
• Minimum set of cost contributorso Design costs (fixed)o Production setup costs (fixed)o Parts and assembly cost (per unit)o Support costs (per year of utilization)
• Should also consider the “time value of money”o Discount rate allows money spent in future to be compared to
present costs
Cont..
Simple Cost AnalysisSimple Cost Analysis
Life-Cycle Cost ComponentsLife-Cycle Cost Components
• Design costs -- salaries, offices, labs, ...o Conceptual design and specificationo Design and developmento Test and validation
• Production costso Setupo Partso Assemblyo Testo Packagingo Distribution
Cont..
Life-Cycle Cost ComponentsLife-Cycle Cost Components
• Support costso Customer supporto Repairo Diagnosis and repair equipmento Distribution
Example: Design-Independent Example: Design-Independent ParametersParameters
Example: Design-Dependent Example: Design-Dependent Parameters (1)Parameters (1)
•Component and board costs ...
Example: Design-Dependent Example: Design-Dependent Parameters (2)Parameters (2)
•Other design-dependent costs ...
Example: Model SummaryExample: Model Summary•The baseline design ...
Example: Design Alternative 1Example: Design Alternative 1
•Design alternative 1:
oCheaper, but less reliable SRAM part ($3.25 versus $4.25)
oTwo days per year support costs for alternative 1 versus 1 day per year for baseline
•Comparison to baseline Baseline Alternative 1
oSimple total cost per unit: $148 $152
oAdjusted total cost per unit: $125 $129
Cont..
Example: Design Alternative 1Example: Design Alternative 1
Example: Design Alternative 2Example: Design Alternative 2
Cont..
• Design alternative 2:o More expensive, but less complex/more familiar SRAM part
($7.00 versus $4.25)o 3 days hardware design time for alternative 2 versus 4 days for
baseline
• Comparison to baseline Baseline Alternative 2o Simple total cost per unit: $148 $148o Adjusted total cost per unit: $125 $124
Example: Design Alternative 2Example: Design Alternative 2