系统工程第二章.pptx

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1、5:12 下午1 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-understood product line,or process,for the acquisition or production of large systems,it is very likely that there w

2、ill 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 very important.第1页/共112页5:12 下午22.1 INTRODUCTION In this chapter we first discuss the nature of systems acquisition

3、（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 primarily concerned with the functional and physical architectures that lead to implementation architectures and the resulting detaile

4、d 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 and deployment（部署）phases of the life cycle.Design and development is a creative process through which system products,presumed to be

5、 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 be maintained over time.第2页/共112页5:12 下午32.1 INTRODUCTION There are four primary ingredients in our definition of design and developm

6、ent,and they apply to software design as well as to the design of hardware and physical systems.Development results from specifications（规格）or architecture for a product or system.Development is a creative process.Development activity includes design effort,which is conceptual in nature.A successful

7、design and development must be broadly responsive to client needs and requirements.第3页/共112页5:12 下午42.1 INTRODUCTION Good systems 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

8、 requires a set of needs and requirements of the client for the desired product,process,or system.This information requirement 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 nat

9、ure.The initial result of this creative,conceptual,and pragmatic process is information concerning the specifications or architecture 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

10、and plans for its evolution over time.第4页/共112页5:12 下午52.1 INTRODUCTION In the detailed efforts that follow,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 fo

11、r systems engineering processes.第5页/共112页5:12 下午62.1 INTRODUCTION In this chapter,we will discuss the systems acquisition,or production,process in terms of a number of steps and phases that may comprise this process.第6页/共112页5:12 下午72.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION

12、 In this section we present and explain the complete systems engineering 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

13、life cycle phasesA perspectives dimension（观点层面）that consists of three stages or life cycles第7页/共112页5:12 下午82.2 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.

14、2.This three-level structured hierarchy comprises a systems engineering life cycle and is one of the ingredients of systems engineering methodology.It involves:System definitionSystem developmentSystem deployment第8页/共112页5:12 下午92.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION We

15、illustrate forward 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）第9页/共112页5:12 下午102.2 METHODOLOGICAL FRAMEWORK

16、S 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,d

17、iscuss some extensions of the basic waterfall life-cycle model,illustrated on the left side of Figure 2.3.第10页/共112页5:12 下午112.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION As we shall soon discuss,this three-phase life cycle may be expanded into a life cycle comprised（包含）of a la

18、rger 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 第11页/共112页5:12 下午122.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION Regardless of（不管、尽管）the way in which the systems engineering life-cy

19、cle 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 needs and objectives of a client group are

20、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 the options,or alternative courses of act

21、ion,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 for implementation or further study in a

22、subsequent phase of systems engineering.第12页/共112页5:12 下午132.2 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 conceptualization.As we shall also indicate in much more detail l

23、ater,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.第13页/共112页5:12 下午142.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION As we have noted,there are generally three differ

24、ent 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)System acquisition or productionSystems planning and marketing 第14页/共112页5:12 下午152

25、.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 cycle,the phases in the life cycle,and the life cycles that comprise the coarse structure（大体框架）or st

26、ages of systems engineering.第15页/共112页5:12 下午162.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION Figure 2.5 illustrates this across three distinct but interrelated life cycles,for the three steps and three phases that we have described here.第16页/共112页5:12 下午172.2 METHODOLOGICAL FRA

27、MEWORKS 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 research,development,test,and evaluation life cycle is intended to yield answers to the question;What is(technologically)possible(within reas

28、onable 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 where there is overlap（重叠）,actually in an n-dimensional space,that responsible actions should be implemented to bring about programs for al

29、l three life cycles.This suggests that the needs of one life cycle should not be considered independently of the other two.第17页/共112页5:12 下午182.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION Figure 2.6 attempts to represent this conceptually for two-dimensional representations of

30、the possibility space for each life cycle.第18页/共112页5:12 下午192.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION 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 st

31、ages for a complete systems engineering effort,as we have indicated.Thus we may imagine a three-dimensional model of systems 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

32、effort.第19页/共112页5:12 下午202.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION Figure 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

33、.第20页/共112页5:12 下午212.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION 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

34、use a methodology we must have an appropriate set of methods.Generally,these include 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,developm

35、ent,and deployment of both an appropriate process and the product that results from use of this process.Associated with a methodology is a structured framework into which particular methods are associated for resolution of a specific issue.第21页/共112页5:12 下午222.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS

36、 ACQUISITION OR PRODUCTION Let us now develop the structured framework of steps,phases,and stages in systems engineering in more detail.第22页/共112页5:12 下午23(1)Logical Steps of Systems Engineering As we have noted,all characterizations of systems engineering will necessarily involve three logical step

37、s 1-4:Formulation of the systems engineering 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

38、steps,or an expansion thereto to more explicitly indicate the actual activities associated with each phase,are conducted at each and every phase of the systems engineering life cycle.第23页/共112页5:12 下午24(1)Logical Steps of Systems Engineering We can expand（扩展）the three fundamental steps of systems en

39、gineering in many ways.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.第24页/共112页5:12 下午25(1)Logical Steps of

40、 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

41、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

42、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

43、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.第25页/共112页5:12 下午26(1)Logical Steps of S

44、ystems 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 to such important con

45、cerns 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,we attempt to adjust,

46、and hopefully optimize,the system variables in order to best meet system objectives and satisfy system constraints.第26页/共112页5:12 下午27(1)Logical Steps of Systems Engineering Interpretation Decision Making（制定策略）.This step involves evaluating the impacts or consequences of the alternatives and,thereby

47、,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 associated with the value system.This enables

48、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 results of the effort to this point and l

49、ooking ahead to the next phase of the systems engineering life cycle under consideration.This includes such pragmatic efforts as scheduling subsequent efforts,allocating resources to accomplish them,and setting up system management controls.If we are conducting a single phase effort,this step would

50、be the final one.More generally,it leads to a new phase of effort in continuation of a systems engineering life cycle.第27页/共112页5:12 下午28(1)Logical Steps of Systems Engineering figure 2.8 indicates the waterfall nature of these seven steps of systems engineering and their relation to the three funda