【正文】 mize, the system variables in order to best meet system objectives and satisfy system constraints. 上午 4時 12分 2022 SYSTEMS ENGINEERING 28 (1) Logical Steps of Systems Engineering Interpretation ⑥ Decision Making （ 制定策略 ） . 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 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 interpretation of these evaluations such that all alternatives can be pared relative to human values. One or more alternatives, or courses of action, can then be selected for advancing to the next step. ⑦ Planning for Action. This step involves municating the results of the effort to this point and looking 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 acplish them, and setting up system management controls. If we are conducting a single phase effort, this step would be the final one. More generally, it leads to a new phase of effort in continuation of a systems engineering life cycle. 上午 4時 12分 2022 SYSTEMS ENGINEERING 29 (1) Logical Steps of Systems Engineering figure indicates the waterfall nature of these seven steps of systems engineering and their relation to the three fundamental logical steps. The seven steps of systems engineering are generally carried out in an iterative fashion for each phase of the systems engineering life cycle. 上午 4時 12分 2022 SYSTEMS ENGINEERING 30 (1) Logical Steps of Systems Engineering Because the efforts and purposes of the various phases of the life cycle are quite different, the specific tools and methods that are appropriate to acplish each of the seven steps can be expected to be quite different from one systems engineering process phase to another. It is quite possible to go back to refine and improve the results of any earlier step as a consequence of the results of any later step. We do not show these iterative feedback loops in Figure . 上午 4時 12分 2022 SYSTEMS ENGINEERING 31 (2) LifeCycle Phases of Systems Engineering As we have often indicated a typical systems engineering life cycle has three basic phases— definition, development, and deployment. For large systems, these three phases need expansion into a number of more finely defined phases. This enables the various phases to be better understood, municated, and controlled in order to support trustworthy systems engineering efforts. Before describing specific lifecycle methodologies later in this chapter, we present and explain a general and very useful sevenphase lifecycle expansion and its relation to the basic threephase systems engineering life cycle that we presented in Figures and . Figure illustrates the sevenphase life cycle, actually representing acquisition or production, that we now consider. 上午 4時 12分 2022 SYSTEMS ENGINEERING 32 (2) LifeCycle Phases of Systems Engineering The seven phases in this life cycle may be described as follows: 上午 4時 12分 2022 SYSTEMS ENGINEERING 33 (2) LifeCycle Phases of Systems Engineering System Definition 1. Requirement and Specifications. The first part of system engineering effort results in the identification of user requirements and the translation of these into technological specification for a product, process, or system. The goal of this phase is the identification of client and stakeholder needs, activities, and objectives for the functionally operational system. This means that information is a necessary ingredient and results in the mandate to obtain, from the client for a systems engineering effort, a set of needs and requirements for the product, process, or system that is to result from the effort. This information requirement serves as the input to the rest of the systems engineering process. This phase results in the identification and description of preliminary conceptual design considerations for the next phase. It is necessary to translate operational deployment needs into requirements specifications so that these needs may be addressed by the system design and development efforts. Thus, information requirements specifications are affected by, as well as affect, each of the other design and development phases of the systems engineering life cycle. 上午 4時 12分 2022 SYSTEMS ENGINEERING 34 (2) LifeCycle Phases of Systems Engineering 2. Preliminary Conceptual Design and System Architecting. The primary goal of this phase is to develop several concepts that might work that are responsive to the specifications identified in the previous phase of the life cycle. A preliminary conceptual design, one that is responsive to user requirements for the system and associated technical specifications, should be obtained. Rapid prototyping of the conceptual design is clearly desirable for many applications as one way of achieving an appropriate conceptual design. Several potential options are identified and then subjected to at least a preliminary evaluation in order to eliminate clearly unacceptable alternatives. The surviving alternatives are next subjected to more detailed design efforts, and more plete architectures or specifications are obtained. It is at this phase that the enterprise architecture, and perhaps a preliminary functional architecture, for the system are init