工程项目的系统分析

1、工程项目的系统分析工程项目的系统分析System Approach1. 系统的定义与基本概念系统的定义与基本概念 A set of interrelated and interdependent parts arranged in a manner that produces a unified whole. 系统是由相互作用和相互依赖的若干组成部分系统是由相互作用和相互依赖的若干组成部分(要素要素)结合而成的、具有特定功能的有机整体。结合而成的、具有特定功能的有机整体。 系统必须由两个以上的要素组成系统必须由两个以上的要素组成 要素与要素之间存在着一定的有机联系要素与要素之间存在着一定的有机

2、联系 任何系统都有特定的功能任何系统都有特定的功能Definition of systemAn organized or complex whole; an assemblage of things or parts interacting in a coordinated way.Besides being an “assemblage of parts ”, the definition of system should include three other features: Parts of the system are affected by being the system an

3、d are changed if they leave it; The assemblage of parts does something; The assemblage is of particular interest.The first feature means that, in systems, the whole is more than the sum of the parts. The name given to a way of viewing things in terms of their “wholeness”, or the whole being more tha

4、n the sum of the parts, is holism. Holism is the opposite of reductionism, which says that the things can be understood by simply breaking them down and understanding the pieces.The second feature of systems is that they are dynamic and exhibit some kind of behavior; they do something. The kind of b

5、ehavior they exhibit depends upon the particular kind of system at hand. System behavior can usually be observed in the outputs of the system or the way the system converts inputs to outputs, though the conversion process and the outputs may be quite obscure.Third, systems are conceived by the peopl

6、e looking at them, which means they exist in the eye (or mind) of the beholder. This is not to say that they fail to exist unless someone is there to see them, but rather that the conception of a system can be altered to suit ones purpose.2、系统的基本概念、系统的基本概念 Elements and subsystemsThe smallest part of

7、 a system is an element.A subsystem is a system that functions as a component of a larger system. When it is unnecessary to understand or reveal its inner workings, a subsystem can simply be thought of as an element. AttributesSystems, subsystems, and elements all have distinguishing characteristics

8、 and properties. These attributes describe or express the condition of systems, subsystems and elements in qualitative or quantitative terms. Environment and boundaryThe term environment is used to refer to anything that lies beyond the decision makers control yet influences the behavior or outcome

9、of the system.A system is separated from its environment by a boundary. ObjectivesHuman-made systems are designed to do something. They have objectives that conceived by people. One of the greatest aids for conceptualizing, creating, or investigating a system is to begin with a clear, concise statem

10、ent of the system objectives. Frequently objectives are broken down into a hierarchy of objectives. System structureElements and subsystems are linked together by relationships. The form taken by the relationships is referred to as the structure of the system.Most systems, including projects, can be

11、 conceptualized as both hierarchical and network systems. Inputs, process, outputsHuman-made systems accomplish things by converting inputs into outputs through a well-defined process.The system input that originates from the system itself is called feedback.InputsProcessOutputsFeedback Open & c

12、losed systemsIn contrast to machines, biological and social systems are not closed. They are open systems, which means they interact with the environment and have the capability to adapt to environment as well.Constraints and conflictsSystems have constraints or limitations imposed both from within

13、and by the environment, which may inhibit their ability to reach objectives.In human organizations, and especially in projects, the objectives of subsystems are frequently in conflict. IntegrationA systems elements and subsystems must perform in a synergistic fashion. All of the elements, the “assem

14、blage of parts”, must work in unison.Designing, implementing, and operating a system that adapts to changing environmental requirements and achieves effective, coordinated(so-called seamless) functioning of its elements and subsystems is called systems integration.系统工程方法论系统工程方法论 系统工程的方法论，是指运用系统工程研究问

15、题系统工程的方法论，是指运用系统工程研究问题的一套程序化方法，也就是为了达到系统的预期目的一套程序化方法，也就是为了达到系统的预期目标，运用系统工程思想及技术内容，解决问题的工标，运用系统工程思想及技术内容，解决问题的工作步骤。作步骤。 系统工程方法论的特点是，从系统工程方法论的特点是，从系统思想和观点系统思想和观点出发，将系统工程所要解决的问题放在系统的形式出发，将系统工程所要解决的问题放在系统的形式中加以考察，始终围绕着系统的中加以考察，始终围绕着系统的预期目的预期目的，从整体，从整体与部分、部分与部分和整体与外部环境的相互联系、与部分、部分与部分和整体与外部环境的相互联系、相互作用、相互

16、矛盾、相互制约的关系中综合地考相互作用、相互矛盾、相互制约的关系中综合地考察对象，以达到察对象，以达到最优地处理问题最优地处理问题的效果。的效果。系统工程方法论的基本原则系统工程方法论的基本原则 系统整体性原则系统整体性原则 系统工程方法论要求把研究对象（任务、项目）系统工程方法论要求把研究对象（任务、项目）都看成由不同部分构成的有机整体，把全局观点、都看成由不同部分构成的有机整体，把全局观点、整体观点贯彻于整个项目（任务）的各个方面、各整体观点贯彻于整个项目（任务）的各个方面、各个部分、各个阶段，从整体上搞好局部的协调。个部分、各个阶段，从整体上搞好局部的协调。 系统有序相关原则系统有序相关

17、原则 系统的有序性，是系统有机联系的反映，系统系统的有序性，是系统有机联系的反映，系统的任何联系都是按一定等级和层次进行的，都是秩的任何联系都是按一定等级和层次进行的，都是秩序井然、有条不紊的。在系统层次上表现出来的整序井然、有条不紊的。在系统层次上表现出来的整体特性是由要素或分系统层次相互关联、相互制约体特性是由要素或分系统层次相互关联、相互制约所形成的。所形成的。 系统目标优化原则系统目标优化原则 最优化的概念贯穿于系统工程的始终，它是系最优化的概念贯穿于系统工程的始终，它是系统工程的指导思想和追求目标。在系统工程中普遍统工程的指导思想和追求目标。在系统工程中普遍运用最优化原则，就能使系统

18、取得满意效果和最佳运用最优化原则，就能使系统取得满意效果和最佳效益。效益。 系统动态性原则系统动态性原则 研究对象内部复杂的相互作用和外部的环境研究对象内部复杂的相互作用和外部的环境多变性，使呈现出系统工程本身动态特性。因此，多变性，使呈现出系统工程本身动态特性。因此，应把实施对象看做一个动态过程，分析系统内外的应把实施对象看做一个动态过程，分析系统内外的各种变化，掌握变化的性质、方向和趋势，采取相各种变化，掌握变化的性质、方向和趋势，采取相应的措施和手段，改进工作方法，调整规划和计划，应的措施和手段，改进工作方法，调整规划和计划，在动态变化中求得系统的整体优化。在动态变化中求得系统的整体优化

19、。 系统分解综合原则系统分解综合原则 分解是将具有比较密切相关的关系要素进行分分解是将具有比较密切相关的关系要素进行分组，对系统来说就是归纳出相对对立、层次不同的组，对系统来说就是归纳出相对对立、层次不同的分系统；综合则是完成新系统的筹建过程，即选择分系统；综合则是完成新系统的筹建过程，即选择具有性能好、适用性强的分系统，设计出它们的相具有性能好、适用性强的分系统，设计出它们的相互关系，形成具有更广泛价值的系统，以达到预定互关系，形成具有更广泛价值的系统，以达到预定的目的。的目的。 系统创造性思维原则系统创造性思维原则 把陌生的事物看成是熟悉的东西，用已有的知把陌生的事物看成是熟悉的东西，用已

20、有的知识加以辨识和解决；把熟悉的事物看成是陌生的东识加以辨识和解决；把熟悉的事物看成是陌生的东西，用新的方法、新的原理加以研究，从而创造出西，用新的方法、新的原理加以研究，从而创造出新的理论、新的技术。新的理论、新的技术。Three common ways of applying the systems approach, called “system methodologies”, are systems analysis, systems engineering, and systems management. Each has a different purpose and scope,

21、 but all share a similar, systems view of the world.Systems approachAn appreciation of the systems approach is important for project managers because it is the approach that underlines the process of project management. Especially in technical projects, many of the steps and procedures are prescribe

22、d according to systems methodologies. Throughout projects there is often a need to apply a problem-solving approach called “systems analysis”; in large-scale engineering and developmental projects, the approach followed is called “systems engineering”; and most large projects are managed as systems,

23、 a process called “systems management”.No problem can be solved in isolation. Every problem is inextricably united to the environment, and attempts to solve it may cause other, more intractable problems. Churchman calls this the “environmental fallacy.”Examples abound of situations where solutions f

24、or the parts have led to worse problems for the whole.The systems approach tries to avoid the environmental fallacy. Systems analysisSystems analysis is a problem-solving framework to help decision makers select the best alternatives. By one definition, “systems analysis is a systematic examination

25、of a problem in which each step of the analysis is made explicit. Consequently, it is the opposite of a manner of reaching decisions which is largely intuitive, unsystematic, and where much of the argument remains hidden in the mind of the decision maker or his advisor. ” Thus, what distinguishes sy

26、stems analysis from other forms of analysis is the precision in defining the elements of the analysis.Process of conducting a systems analysisDecision makerProblem formulationObjectivesCriteriaResources/constraintsAlternativesAnalysis modelRedo systems analysisReject alternativesAccept alternative(s

27、)FormulationResearchAnalysis/judgmentVerification Elements of systems analysis Objective(s). The first task in systems analysis is to identify the decision makers and what they expect after the problem has been solved. This expectation is the objective. Objectives must be clear, concise, andideallym

28、easurable. To eliminate confusion and misunderstanding about the problem or system, both the decision maker and the systems analyst must agree to the objectives. Criteria. Criteria are performance measures that will enable the analyst to determine the extent to which objectives are being achieved. T

29、hey are the basis for ranking the performance of alternative solutions or courses of action to the problem. In projects, the criteria are referred to as requirements and specifications. Alternatives. Alternatives are potential solutions to problems and courses of action for attaining objectives. The

30、 common error in many analyses is to focus on the familiar alternatives and ignore innovative solutions. Ideally, a wide range of alternative solutions are considered. Resources and constraints. Resources are elements of the systemlabor, time, capital, materialsavailable to solve the problem. Constr

31、aints are elements of the system or environment that restrict the applicability or usefulness of alternatives. Resources and constraints determine what is feasible and reduce the number of potential solutions to a problem. Analysis model. The model incorporates all of the above elements so that cons

32、equences of all alternatives can be compared in terms of attainment of objectives.In doing systems analysis, one must be careful not to catch “modelism”in other words, not become more interested in the model than in the real world. Modelism leads to the study of irrelevant or over-idealized question

33、s rather than answers to important questions.Systems engineeringSystems engineering has been defined as “the science of designing complex systems in their totality to insure that the component subsystems making up the system are designed, fitted together, checked and operated in the most efficient w

34、ay.”Up through World War II, the term “systems engineering” referred to integrating existing components into a final product. Today it emphasizes instead the conception, design, and development of complex systems where the components themselves must be designed and developed from scratch and integra

35、ted together to fulfill mission objectives.In contrast to systems analysis, which focuses on decisions about a system, systems engineering is a way to actually bring a system into being.SystemConceptSystem Definition/Preliminary DesignDetailed Design/System DevelopmentSystems EvaluationConstruction/

36、ProductionSystem Operation/SupportSystems EvaluationSystem Phase-outSystems Engineering Process Stages of systems engineering System concept. Clarify the problem, establish the need and value for the system; set overall mission, objectives, and operational and maintenance requirements for the system

37、. System definition and preliminary design. Determine major functions of the system; cluster functions to form subsystems; perform systems analysis to evaluate design alternatives; prepare design specifications. Detailed design and development. Describe in detail subsystems, units, assemblies; devel

38、op models to test performance and integration of design; prepare for production of systemSystem production or fabrication. Maintain construction/production operation and produce the system;prepare for installation of system. System operation and support. Check out and install system within the user

39、environment; provide maintenance, field support, and system enhancement as necessary to ensure continued compliance with objectives; phase out system at the end of its useful life.A third application of the systems approach is systems management, the management and operation of organizations as syst

40、ems. Three major characteristics distinguish systems management. Systems managementFirst, it is total-system oriented and emphasizes achievement of the overall system mission and system objectives. Second, it emphasizes decisions that optimize the overall system rather than subsystems. Third, it is

41、responsibility-oriented. The manager of each subsystem is given specific assignments so that inputs, outputs, and contribution to total system effectiveness can be measured. Systems management works to ensure that organizations, responsibilities, knowledge, and data are integrated toward achieving o

42、verall objectives. Thus, the orientation of the systems manager is to consider the interactions and interdependencies between various subsystems and with the environment.The relationships between systems management, systems analysis, and systems engineering can be explained in terms of when they are

43、 applied during the life cycle of a system.Systems management performs the basic managerial functions of planning, organization, and control throughout the life of a system, but the focus remains on coordinating and integrating work rather than actually performing it.Systems management often works p

44、arallel with systems engineering and utilizes the tools of systems analysis. The purpose of systems analysis is to ask questions about the goal or mission of the system, the kind and nature of resources to use, and the organization of people and facilities. In systems management, systems analysis is

45、 used to plan and control activities and materials, and to evaluate system operation to determine when and why the system is not functioning properly.Systems management entails identification of total system requirements, control over the evolution of requirements and design, integration of technica

46、l efforts, and development of data and documentation. It is applied over the full life cycle of the system (systems development management; systems operations management)Systems analysisSystems managementSystems engineeringConcept-design-fabricationDevelopmentOperationSystem Life CyclePrimary activi

47、tySecondary or as needed activityA. D. Hall的的“三维结构体系三维结构体系”知识维知识维时间维时间维逻辑维逻辑维社会科学社会科学工程技术工程技术法律法律明确问题明确问题 系统指标设计系统指标设计系统方案综合系统方案综合 系统分析系统分析 方案选择方案选择 方案决定方案决定 实施计划实施计划规划阶段规划阶段拟定方案阶段拟定方案阶段系统研制阶段系统研制阶段生产阶段生产阶段装配阶段装配阶段运行阶段运行阶段更新阶段更新阶段系统工程活动矩阵系统工程活动矩阵时间维逻辑维时间维逻辑维P. Checkland的软系统方法论的软系统方法论问题现状说明问题现状说明(无结构

48、问题无结构问题)搞清问题的关搞清问题的关联因素联因素说明现状说明现状,目的是为了改善现状目的是为了改善现状,弄清问题弄清问题本身的基本定义本身的基本定义搞清楚与改善有关的各种因素及因素间搞清楚与改善有关的各种因素及因素间的相互关系的相互关系概念模型概念模型比较比较实施实施运用系统观点和系统思考描述系统活动的运用系统观点和系统思考描述系统活动的现状现状,可用结构模型和有流向的框图表达可用结构模型和有流向的框图表达根据数学模型的理论和方法根据数学模型的理论和方法,改进上述概念改进上述概念模型模型,然后将概念模型和现状进行比较然后将概念模型和现状进行比较,逐逐步得出满意的可行解步得出满意的可行解对改善问题予以实施对改善问题予以实施Project breakdown determines what is referred to as a projects work breakdown structure (WBS), which is basically a breakdown of the whole project into component parts. The WBS is created as a logic hierarchical decomposition