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1、Chapter 2 Methodological Frameworks and Systems Engineering Processes(方法论框架和系统工程过程),2023/6/23,2007 SYSTEMS ENGINEERING,2,There are a number of frameworks（框架、体系）that we might use to characterize（描绘）systems engineering efforts.We will describe some of them in this chapter.Without a sound and well-unde
2、rstood product line,or process,for the acquisition or production of large systems,it is very likely that there will be a number of flaws（缺点）in the resulting system itself.Thus,the definition,development,and deployment（部署）of an appropriate（恰当的）process,or set of processes,for systems production is ver
3、y important.,2023/6/23,2007 SYSTEMS ENGINEERING,3,2.1 INTRODUCTION,In this chapter we first discuss the nature of systems acquisition（收购）,production（生产）,procurement（采购）,or manufacturing（制造业）.We will generally（通常）use the word acquisition to describe each of these efforts.As systems engineers,we are p
4、rimarily concerned with the functional and physical architectures that lead to implementation architectures and the resulting detailed design of systems of all types.Design and development is very important,even though the acquisition or production process also depends upon success in the definition
5、 and deployment（部署）phases of the life cycle.Design and development is a creative process through which system products,presumed to be responsive to client needs and requirements,are conceptualized or specified,manufactured or otherwise produced,and fielded or implemented in such a way that they can
6、be maintained over time.,2023/6/23,2007 SYSTEMS ENGINEERING,4,2.1 INTRODUCTION,There are four primary ingredients in our definition of design and development,and they apply to software design as well as to the design of hardware and physical systems.Development results from specifications（规格）or arch
7、itecture for a product or system.Development is a creative process.Development activity includes design effort,which is conceptual in nature.A successful design and development must be broadly responsive to client needs and requirements.,2023/6/23,2007 SYSTEMS ENGINEERING,5,2.1 INTRODUCTION,Good sys
8、tems engineering practice（实践）requires that the systems engineer be responsive to each of these four ingredients for quality design and development efforts.The final ingredient requires a set of needs and requirements of the client for the desired product,process,or system.This information requiremen
9、t serves as the input to the systems engineering process that leads to design.Systems engineering is creative,and it is a process that is conceptual and pragmatic（概念和务实）in nature.The initial result of this creative,conceptual,and pragmatic process is information concerning the specifications or arch
10、itecture for the product or service that will ultimately be manufactured,implemented,installed,or brought to fruition（享用）in some other way.A later result is the system itself and plans for its evolution over time.,2023/6/23,2007 SYSTEMS ENGINEERING,6,2.1 INTRODUCTION,In the detailed efforts that fol
11、low,we first discuss systems engineering methodology and systems engineering life cycles as necessary elements in the systems engineering process.This leads to a number of conceptual frameworks for systems engineering processes.,2023/6/23,2007 SYSTEMS ENGINEERING,7,2.1 INTRODUCTION,In this chapter,w
12、e will discuss the systems acquisition,or production,process in terms of a number of steps and phases that may comprise this process.,2023/6/23,2007 SYSTEMS ENGINEERING,8,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,In this section we present and explain the complete systems e
13、ngineering process with emphasis on frameworks for systems methodology and design.The framework consists of three dimensions（方面）:A logic dimension（逻辑层面）that consists of three fundamental stepsA time dimension that consists of three basic life cycle phasesA perspectives dimension（观点层面）that consists o
14、f three stages or life cycles,2023/6/23,2007 SYSTEMS ENGINEERING,9,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,We envision（设想）a three-performance level hierarchy（三层次结构性能）for systems engineering phased efforts,such as shown in Figure 2.2.This three-level structured hierarchy c
15、omprises a systems engineering life cycle and is one of the ingredients of systems engineering methodology.It involves:System definitionSystem developmentSystem deployment,2023/6/23,2007 SYSTEMS ENGINEERING,10,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,We illustrate forward
16、flow of information,and feedback（反馈）from one phase to the other.Usually,this is needed as a situation in which information only flows in one direction from one phase to a subsequent phase will not allow for iterative improvement.（迭代改进）,2023/6/23,2007 SYSTEMS ENGINEERING,11,2.2 METHODOLOGICAL FRAMEWO
17、RKS FOR SYSTEMS ACQUISITION OR PRODUCTION,It is generally also very desirable to allow for learning as the life-cycle process is iteratively repeated（反复迭代）.Figure 2.3 illustrates three different information flow patterns.Generally,the one with learning and feedback is to be preferred.We will,however
18、,discuss some extensions of the basic waterfall life-cycle model,illustrated on the left side of Figure 2.3.,2023/6/23,2007 SYSTEMS ENGINEERING,12,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,As we shall soon discuss,this three-phase life cycle may be expanded into a life cycl
19、e comprised（包含）of a larger number of phases.Generally the number of phases is in the vicinity（周围地区）of seven,although it may contain quite a few more than seven phases,2023/6/23,2007 SYSTEMS ENGINEERING,13,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,Regardless of（不管、尽管）the way
20、 in which the systems engineering life-cycle process is characterized,and regardless of the type of product or system or service that is being designed,all characterizations of the phases of the systems engineering life cycles will necessarily involve:Formulation of the Problem（问题的规划）in which the ne
21、eds and objectives of a client group are identified,and potentially acceptable design alternatives,or options,are identified or generated.Analysis of the Alternatives（变量的分析）in which the impacts of the identified design options are identified and evaluated.Interpretation（解释、说明）and Selection in which
22、the options,or alternative courses of action,are compared by means of an evaluation of the impacts of the alternatives and how these are valued by the client group.The needs and objectives of the client group are necessarily used as a basis for evaluation.The most acceptable alternative is selected
23、for implementation or further study in a subsequent phase of systems engineering.,2023/6/23,2007 SYSTEMS ENGINEERING,14,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,Our model of the steps of the logic structure of the systems process,shown in Figure 2.4,is based upon this conc
24、eptualization.As we shall also indicate in much more detail later,these three steps can be disaggregated（分解）into a number of others.Each of these steps of systems engineering is accomplished for each of the life cycle phases.,2023/6/23,2007 SYSTEMS ENGINEERING,15,2.2 METHODOLOGICAL FRAMEWORKS FOR SY
25、STEMS ACQUISITION OR PRODUCTION,As we have noted,there are generally three different systems engineering life cycles.These relate to the three different stages of effort that are needed to result in a competitive product or service in the marketplace:Research,development,test,and evaluation(RDT&E)Sy
26、stem acquisition or productionSystems planning and marketing,2023/6/23,2007 SYSTEMS ENGINEERING,16,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,Thus we may imagine a three-dimensional model of systems engineering that is comprised of steps associated with each phase of a life
27、cycle,the phases in the life cycle,and the life cycles that comprise the coarse structure（大体框架）or stages of systems engineering.,2023/6/23,2007 SYSTEMS ENGINEERING,17,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,Figure 2.5 illustrates this across three distinct but interrelate
28、d life cycles,for the three steps and three phases that we have described here.,2023/6/23,2007 SYSTEMS ENGINEERING,18,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,The systems planning and marketing life cycle is intended to yield answers to the question;What is in demand?The r
29、esearch,development,test,and evaluation life cycle is intended to yield answers to the question;What is(technologically)possible(within reasonable economic and other considerations)?The acquisition life cycle is intended to yield answers to the question;What can be developed?It is only in the region
30、 where there is overlap（重叠）,actually in an n-dimensional space,that responsible actions should be implemented to bring about programs for all three life cycles.This suggests that the needs of one life cycle should not be considered independently of the other two.,2023/6/23,2007 SYSTEMS ENGINEERING,1
31、9,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,Figure 2.6 attempts to represent this conceptually for two-dimensional representations of the possibility space for each life cycle.,2023/6/23,2007 SYSTEMS ENGINEERING,20,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PR
32、ODUCTION,Each of the logical steps of systems engineering is accomplished for each of the life-cycle phases.There are generally three different systems engineering lifecycles or stages for a complete systems engineering effort,as we have indicated.Thus we may imagine a three-dimensional model of sys
33、tems engineering that is comprised of steps associated with each phase of a life cycle,the phases in the life cycle,and the life cycles or stages of a complete systems engineering effort.,2023/6/23,2007 SYSTEMS ENGINEERING,21,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,Figure
34、 2.7 illustrates this framework of steps（步骤）,phases（方面）,and stages（阶段）as a three-dimensional cube.This is one three-dimensional framework,in the form of a morphological（形态学）box,for systems engineering.,2023/6/23,2007 SYSTEMS ENGINEERING,22,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRO
35、DUCTION,A methodology（方法学）is an open set of procedures for problem solving.Consequently（因此、所以）,a methodology involves a set of methods,a set of activities,and a set of relations between the methods and the activities.To use a methodology we must have an appropriate set of methods.Generally,these inc
36、lude a variety of qualitative（定性的）and quantitative approaches from a number of disciplines that enable formulation（构思、规划）,analysis,and interpretation of the phased efforts that are associated with the definition,development,and deployment of both an appropriate process and the product that results f
37、rom use of this process.Associated with a methodology is a structured framework into which particular methods are associated for resolution of a specific issue.,2023/6/23,2007 SYSTEMS ENGINEERING,23,2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION,Let us now develop the structured
38、 framework of steps,phases,and stages in systems engineering in more detail.,2023/6/23,2007 SYSTEMS ENGINEERING,24,(1)Logical Steps of Systems Engineering,As we have noted,all characterizations of systems engineering will necessarily involve three logical steps 1-4:Formulation of the systems enginee
39、ring problem under considerationAnalysis to determine the impacts of the alternativesInterpretation of these impacts in accordance with the value system of the decision maker(s),and selection of an appropriate plan of action to continue the effort.These three steps,or an expansion thereto to more ex
40、plicitly indicate the actual activities associated with each phase,are conducted at each and every phase of the systems engineering life cycle.,2023/6/23,2007 SYSTEMS ENGINEERING,25,(1)Logical Steps of Systems Engineering,We can expand（扩展）the three fundamental steps of systems engineering in many wa
41、ys.However,probably the most useful expansion is the seven steps identified by Hall 5.Our construal(解释)of these seven steps of systems engineering and their relation to the three basic steps of formulation,analysis,and interpretation follows.,2023/6/23,2007 SYSTEMS ENGINEERING,26,(1)Logical Steps of
42、 Systems Engineering,FormulationProblem Definition.（问题的定义）This step involves isolating（分离）,quantifying（量化）,and clarifying（阐述）the need that creates the problem and describing the set of environmental factors that constrains alterables（约束变量）for the system to be developed.It involves identifying a set
43、of needs,alterables,and constraints associated with the issue formulation.Value System Design.（价值系统设计）This step involves selection of the set of objectives or goals that guides the search for alternatives.Value system design enables determination of the multidimensional attributes or decision criter
44、ia for selecting the most appropriate system.It involves the identification and validation（确认）of a set of objectives and objectives measures.System Synthesis.（系统综合）This step involves searching for,or hypothesizing（假定、猜测）,a set of alternative courses of action or options.Each alternative must be desc
45、ribed in sufficient detail to permit analysis of the impacts of implementation and subsequent evaluation and interpretation with respect to the objectives.As part of this step,we identify a number of potential alternatives and associated alternatives measures.,2023/6/23,2007 SYSTEMS ENGINEERING,27,(
46、1)Logical Steps of Systems Engineering,AnalysisSystem Analysis and Modeling（系统分析与建模）.As a part of this step,we determine specific impacts（确定具体的影响因素）or consequences of the alternatives（变量结果）that were specified as relevant to the issue under consideration by the value system.These impacts may relate t
47、o such important concerns as product quality,market,reliability,cost,and effectiveness or benefits.There are a variety of simulation and modeling methods,and a great variety of operations research approaches that are of potential value here.Refinement of the Alternatives（细化变量）.As part of this step,w
48、e attempt to adjust,and hopefully optimize,the system variables in order to best meet system objectives and satisfy system constraints.,2023/6/23,2007 SYSTEMS ENGINEERING,28,(1)Logical Steps of Systems Engineering,Interpretation Decision Making（制定策略）.This step involves evaluating the impacts or cons
49、equences of the alternatives and,thereby,interpreting the alternatives in terms of the extent to which they achieve objectives.The alternatives are identified in system synthesis and subsequently modeled and refined in the analysis steps of effort,in accordance with satisfaction of objectives associ
50、ated with the value system.This enables interpretation of these evaluations such that all alternatives can be compared relative to human values.One or more alternatives,or courses of action,can then be selected for advancing to the next step.Planning for Action.This step involves communicating the r
