系统工程复习课件

1、系统工程复习1 Systems Engineering Review 系统工程 系统工程复习2 Chapter 1 Introduction to Systems Engineering 系统工程复习3 1.1Attributes Characterizing Systems (1)Four Basic Attributes of the System (1) Assemblage(集合). A system consists of a number of distinguishable units (elements, components, factors, subsystems, etc

2、.), which may be physical or conceptual, natural or artificial. For Example, Consider a university as a system for producing educated graduates. Some of the parts of the university system are structural or static components, such as university buildings. As the system is operating, these structural

3、components usually do not change much. Operating components are dynamic and perform processing such as the professors in a university who teach students. Flow components are often material, energy, or information; but in this example, students are the parts that flow or matriculate through the unive

4、rsity system 系统工程复习4 (2) Relationship. Several units assembled together are merely a group or a set. For such a group to be admissible as a system, a relationship or an interaction must exist among the units. The systems point of view also recognizes that a problem and its solution have many element

5、s or components, and there are many different relations among them. For example, grades are one mechanism（机制） for interaction between professors and students. Grades serve a purpose, intended or not. 1.1.1Four Basic Attributes of the System 系统工程复习5 1.1.1Four Basic Attributes of the System (3) Goal-s

6、eeking. An actual system as a whole performs a certain function or aims at single or multiple objectives. Wherever these objectives are attained at their maximum/minimum levels, system optimization is said to have been performed. An objective that is measurable by any means is called a goal/target.

7、For example ：A manufacturing system effectively converts resources of production into produced goods (products), attaining an objective that creates high utilities by adding values to the raw materials, resulting in superior quality, cost and delivery. 系统工程复习6 1.1.1Four Basic Attributes of the Syste

8、m (4) Adaptability to environment. A specific, factual system behaves so as to adapt to the change in its surroundings, or external environment. For example，A business system is a self- organizing system, in that it generates a diversified variety of activities, resulting in economies of scope. 系统工程

9、复习7 1.2 Systems Defined Four Definitions of Systems On the basis of the foregoing considerations, the four essential definitions of systems can now be given as follows (Hitomi, 1975). 系统工程复习8 1.2 Systems Defined (1) Abstract (or basic) definition. On the basis of the first two attributes above, a sy

10、stem is a collection of recognizable units having relationships among the units. Under this definition, general system theory has been developed, wherein things are deliberated theoretically, logically, and speculatively. 系统工程复习9 1.2 Systems Defined (2) Structural (or static) definition. On the basi

11、s of all four attributes, a system is a collection of recognizable units having relationships among the units, aiming at specified single or multiple objectives subject to its external environment. 系统工程复习10 1.2 Systems Defined n(3) Transformational (or functional) definition. From the last attribute

12、, the effects of the environment upon the system are inputs (including unforeseen disturbances), and, conversely, the effects in which the system influences the environment are outputs. From this consideration a system receives inputs from its environment, transforms them to outputs, and releases th

13、e outputs to the environment, whilst seeking to maximize the productivity of the transformation. 系统工程复习11 1.2 Systems Defined (4) Procedural (or dynamic) definition. The process of transformation in the input-output system consists of a number of related stages, at each of which a specified operatio

14、n is carried out. By performing a complete set of operations according to the precedence relationship on the stages, a function or task is accomplished. Thus, a system is a procedure- -a series of chronological, logical steps by which all repetitive tasks are performed. 系统工程复习12 1.2 DEFINITIONS OF S

15、YSTEMS ENGINEERING TABLE 1.1 Definitions of Systems Engineering nStructureSystems engineering is management technology to assist clients through the formulation, analysis, and interpretation of the impacts of proposed policies, controls, or complete systems upon the need perspectives, institutional

16、perspectives, and value perspectives of stakeholders to issues under consideration. 系统工程复习13 1.2 DEFINITIONS OF SYSTEMS ENGINEERING The structural definition of systems engineering tells us that we are concerned with a framework for problem resolution that, from a formal perspective at least, consis

17、ts of three fundamental steps: nIssue formulation nIssue analysis nIssue interpretation These are each conducted at each of the life-cycle phases that have been chosen in order to implement the basic phased efforts of definition, development, and deployment. 系统工程复习14 1.3 DEFINITIONS OF SYSTEMS ENGIN

18、EERING TABLE 1.1 Definitions of Systems Engineering nFunctionSystems engineering is an appropriate combination of the methods and tools of systems engineering, made possible through use of a suitable methodology and systems management procedures, in a useful process-oriented setting that is appropri

19、ate for the resolution of real-world problems, often of large scale and scope. 系统工程复习15 1.2 DEFINITIONS OF SYSTEMS ENGINEERING The functional definition of systems engineering says that we will be concerned with an appropriate combination of methods and tools. We will denote the result of the effort

20、 to obtain this combination as a systems methodology. Systems engineering methodology is concerned with the life cycle or process used for system evolution. The functional definition of systems engineering also says that we will accomplish this in a useful and appropriate setting. This useful settin

21、g is provided by an appropriate systems management process. 系统工程复习16 1.3 DEFINITIONS OF SYSTEMS ENGINEERING nPurpose The purpose of systems engineering is information and knowledge organization that will assist clients who desire to define, develop, and deploy total systems to achieve a high standar

22、d of overall quality, integrity, and integration as related to performance, trustworthiness, reliability, availability, and maintainability of the resulting system. 系统工程复习17 1.2 DEFINITIONS OF SYSTEMS ENGINEERING We will use the term systems management to refer to the cognitive and organizational ta

23、sks necessary to produce a useful process, methodology, or product line for system evolution and to manage the process-related activities that result in a trustworthy system. More specifically, the result of systems management is an appropriate combination of the methods and tools of systems enginee

24、ring, including their use in a methodological setting, with appropriate leadership in managing system process and product development, to ultimately field a system that can be used by clients to satisfy the needs that led to its development. 系统工程复习18 1.4 SYSTEMS ENGINEERING KNOWLEDGE Figure 1.8 illu

25、strates that systems engineering knowledge is comprised of the following: nKnowledge principles, which generally represent formal problem solving approaches to knowledge, generally employed in new situations and/or unstructured environments。 Knowledge principles include a host of scientific theories

26、. In a sense, these represent the why associated with the functioning of systems. 系统工程复习19 1.4 SYSTEMS ENGINEERING KNOWLEDGE For example, one knowledge principle is that associated with Newtons law. It suggests that force is equal to mass times acceleration and that because acceleration is the deriv

27、ative of velocity and velocity is the derivative of position, we have now. What we have here is a simple model of one-dimensional motion. We could continue to extrapolate on this model of motion, based on Newtons law of mechanics, until we actually come up with a differential equation, 系统工程复习20 1.4

28、SYSTEMS ENGINEERING KNOWLEDGE doubtlessly a very complicated one, that could be used to predict the motion of an automobile when subjected to various forcing functions due to different time histories of accelerator pedal movement and braking controls. Then we could use this differential equation to

29、project the time that would be required to stop a fancy sports car traveling at 60 miles per hour under a certain type of braking action. We would be using knowledge principles to predict the braking effectiveness of this particular car. 系统工程复习21 1.4 SYSTEMS ENGINEERING KNOWLEDGE nKnowledge practice

30、s, which represent the accumulated wisdom and experiences that have led to the development of standard operating policies for well-structured problems。 Alternately, we could develop a set of knowledge practices that are based on actual experimental observations of different drivers breaking differen

31、t cars. 系统工程复习22 1.4 SYSTEMS ENGINEERING KNOWLEDGE Then we could publish such a table. The table might be adopted as a standard, and any particular car that could not stop in the distance specified by the standard might well be subjected to an appropriate repair effort. While the table might have it

32、s basis in the physical differential equations for an automobile, there would not necessarily be any reference to these knowledge principles in obtaining the table. The knowledge principles associated with vehicle motion dynamics would be very useful, however, in the design of various subsystems for

33、 the automobile. 系统工程复习23 1.4 SYSTEMS ENGINEERING KNOWLEDGE nKnowledge perspectives, which represent the view that is held relative to future directions and realities in the technological area under consideration。 Knowledge perspectives are needed when we attempt to project various futures for the a

34、utomobile. For example, we might envision a significant increase in gasoline prices due to an oil embargo. Or we might envision renewed concern for environmental preservation. Each of these 系统工程复习24 1.4 SYSTEMS ENGINEERING KNOWLEDGE could lead to significant interest in smaller size engines, engines

35、 that would result in greater fuel use efficiency at the expense of lower power. This could increase the incentives for electric battery-powered automobiles. For these to be cost-effective, there would have to be a technological revolution in battery storage capacities. There would have to be other

36、changes, such as in societal willingness to accept low- power-capacity automobiles. 系统工程复习25 1.4 SYSTEMS ENGINEERING KNOWLEDGE 系统工程复习26 Chapter 2 Methodological Frameworks and Systems Engineering Processes 系统工程复习27 2.1 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION In this section w

37、e present and explain the complete systems engineering process with emphasis on frameworks for systems methodology and design. The framework consists of three dimensions: nA logic dimension that consists of three fundamental steps nA time dimension that consists of three basic life cycle phases nA p

38、erspectives dimension that consists of three stages or life cycles 系统工程复习28 2.1 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION This three-level structured hierarchy comprises a systems engineering life cycle and is one of the ingredients of systems engineering methodology. It involv

39、es nSystem definition nSystem development nSystem deployment 系统工程复习29 2.1 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

40、 more detail later, these three steps can be disaggregated into a number of others. Each of these steps of systems engineering is accomplished for each of the life cycle phases. 系统工程复习30 2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION As we have noted, there are generally three d

41、ifferent 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: nResearch, development, test, and evaluation (RDT What is in demand? nThe research, development, test, and evaluation life

42、cycle is intended to yield answers to the question; What is (technologically) possible (within reasonable economic and other considerations)? nThe 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）, actual

43、ly 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. 系统工程复习34 2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PR

44、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 o

45、f 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 effort. 系统工程复习35 2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION Figure 2.7 illustrates this

46、framework of steps, phases, and stages as a three-dimensional cube. This is one three-dimensional framework, in the form of a morphological box, for systems engineering. 系统工程复习36 2.2 METHODOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION A methodology （方法学） is an open set of procedures for

47、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 include a variety of qualitative （定性的） and quantitati

48、ve 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 from use of this process. 系统工程复习37 2.2 METHO

49、DOLOGICAL FRAMEWORKS FOR SYSTEMS ACQUISITION OR PRODUCTION Associated with a methodology is a structured framework into which particular methods are associated for resolution of a specific issue. Let us now develop the structured framework of steps, phases, and stages in systems engineering in more

50、detail. 系统工程复习38 (1) Logical Steps of Systems Engineering As we have noted, all characterizations of systems engineering will necessarily involve three logical steps 1-4: nFormulation of the systems engineering problem under consideration nAnalysis to determine the impacts of the alternatives nInter

51、pretation 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 explicitly indicate the actual activities associated with each phase, are conducted at ea

52、ch and every phase of the systems engineering life cycle. 系统工程复习39 (1) Logical Steps of Systems Engineering We can expand （扩展） the three fundamental steps of systems engineering in many ways. However, probably the most useful expansion is the seven steps identified by Hall 5. Our construal(解释) of th

53、ese seven steps of systems engineering and their relation to the three basic steps of formulation, analysis, and interpretation follows. 系统工程复习40 (1) Logical Steps of Systems Engineering Formulation 1. Problem Definition. This step involves isolating, quantifying, and clarifying the need that create

54、s the problem and describing the set of environmental factors that constrains alterables for the system to be developed.It involves identifying a set of needs, alterables, and constraints associated with the issue formulation. 2. Value System Design. This step involves selection of the set of object

55、ives or goals that guides the search for alternatives. Value system design enables determination of the multidimensional attributes or decision criteria for selecting the most appropriate system. It involves the identification and validation of a set of objectives and objectives measures. 系统工程复习41 (

56、1) Logical Steps of Systems Engineering Formulation 3. System Synthesis. This step involves searching for, or hypothesizing, a set of alternative courses of action or options. Each alternative must be described in sufficient detail to permit analysis of the impacts of implementation and subsequent e

57、valuation and interpretation with respect to the objectives. As part of this step, we identify a number of potential alternatives and associated alternatives measures. 系统工程复习42 (1) Logical Steps of Systems Engineering Analysis 4. System Analysis and Modeling. As a part of this step, we determine spe

58、cific impacts or consequences of the alternatives that were specified as relevant to the issue under consideration by the value system. These impacts may relate to such important concerns as product quality, market, reliability, cost, and effectiveness or benefits. There are a variety of simulation

59、and modeling methods, and a great variety of operations research approaches that are of potential value here. 5. Refinement of the Alternatives. As part of this step, we attempt to adjust, and hopefully optimize, the system variables in order to best meet system objectives and satisfy system constra

60、ints. 系统工程复习43 (1) Logical Steps of Systems Engineering Interpretation 6. Decision Making. This step involves evaluating the impacts or consequences of the alternatives and, thereby, interpreting the alternatives in terms of the extent to which they achieve objectives. The alternatives are identifie