1 Chapter 4. Preliminary System Design It is also known as advance development It extends the translation of system level requirement into design requirements for the sub system level

2 The Functional Analysis Process Functional analysis is the iterative process of breaking down requirements from the system level to the sub system FA reflects the “ what ” that must be accomplished to achieve objective & goal Conversion to “ how ” is accomplished by evaluating each individual block, defining the necessary “ inputs ” & expand “ outputs ”

3 Identify need & determine system requirement Operate and maintain system Manufacture System Design and Develop system Control/Constraints Function Input Mechanisms Output Technical Political Sociological Economic Environmental System requirement organizational stru. Raw material Data/documentation HR Material/liquid Computer resources Facilities Maintenance and support System/product ready supporting resources waste Identification of Resources Requirements

4 Requirement Allocation Fig. 4.6 page 112

5 Design Requirements Compatible with the system operational requirements and maintenance Comply with the allocated design criteria Meet all specification requirements

6 Design Requirements(Parameters) Design for functional capability- concerns with chemical,electrical, mechanical design etc –capability derives from the characteristic of design that relates to the functional performance of the system (factors-size, shape, volume Design for reliability- objective is maximize operational reliability and minimize the failure –reliability (R) is often expressed as probability of success

7 Design Requirements(Parameters) Design for maintainability –characteristic of design & installation that reflect the ease, accuracy and safety –it can be measured in terms of maintenance time –minimize the logistic support resources Design for usability and safety –concerned with the interfaces between human & HW, SW etc –consideration must include human sensory, physiological, minimize the number of people and skill requirement, minimize training and maximize productivity

8 Design Requirements(Parameters) Design for supportability/serviceability –ensure that system can ultimately be serviced and support effectively/efficiently through out planned cycle time –includes an application of reliability, maintainability and human factor in design Design for producibility and disposability –characteristic of design that pertains to the ease and economy of producing system/products –using flexible and economical methods –utilization of standard parts –allows for the disassembly and disposal of elements or components of the system easily/rapidly changes

9 Design Requirements(Parameters) Design for affordability –characteristic of design and installation that impact budget constraints –objective is to base design decision on life cycle cost not just system acquisition –economic feasibility on the balanced incorporation of reliability, maintainability, human factor, supportability

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