【正文】 le Phases of Systems Engineering 6. Operational Test and Evaluation (and Associated Modification). Once implementation has occurred, operational evaluation and test of the system can occur. The system design may be modified as a result of this evaluation, leading (hopefully) to an improved system and, ultimately, operational deployment. Generally, the critical issues for evaluation are adaptations of the elements present in the requirements specifications phase of the systems engineering lifecycle process. A set of specific evaluation test requirements and tests are evolved from the objectives and needs determined in the requirements specifications. These should be such that each objective and critical evaluation ponent can be measured by at least one evaluation test instrument. If it is determined, perhaps through an operational test and evaluation, that the resulting systems product cannot meet user needs, the lifecycle process reverts iteratively to an earlier phase, and the effort continues. An important byproduct of system evaluation is determination of ultimate performance limitations for an operationally realizable system. Often, operational evaluation is the only realistic way to establish meaningful information concerning functional effectiveness of the result of a systems engineering effort. Successful evaluation is dependent upon having predetermined explicit evaluation standards. 上午 4時 12分 2022 SYSTEMS ENGINEERING 39 (2) LifeCycle Phases of Systems Engineering 7. Operational Functioning and Maintenance. The last phase includes final acceptance and operational deployment. Maintenance and retrofit can be defined either as part of this phase or as additional phases in the life cycle. Either is an acceptable way to define the system life cycle for system acquisition or production. 上午 4時 12分 2022 SYSTEMS ENGINEERING 40 (2) LifeCycle Phases of Systems Engineering We may summarize these phased activities as follows. The requirements and specification phase of this systems engineering life cycle has as its goal the identification of client or stakeholder needs, activities, and objectives for the functionally operational system. This results in 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 efforts. Thus, user requirements, which are extraordinarily important, and technological system specifications are affected by, as well as affect, each of the other phases of the systems engineering life cycle. 上午 4時 12分 2022 SYSTEMS ENGINEERING 41 (2) LifeCycle Phases of Systems Engineering As a result of the requirements and specifications phase, there should exist a clear definition of system design and development issues such that it bees possible to make a decision concerning whether to undertake preliminary conceptual design. If the requirements specifications effort indicates that client needs can be satisfied in a functionally satisfactorily manner, then documentation is typically prepared concerning specifications for the preliminary conceptual design phase. Initial specifications for the following three phases of effort are typically also prepared, and a concept design team is selected to implement the next phase of the lifecycle effort. This effort is sometimes called functional architecting [7] and sometimes system level architecting [8, 9]. 上午 4時 12分 2022 SYSTEMS ENGINEERING 42 (2) LifeCycle Phases of Systems Engineering Preliminary conceptual system design typically includes, or results in, an effort to specify the content and associated functional architecture and general algorithms for the system product in question. The primary goal of this phase is generally to develop some sort of functional prototype that is responsive to the specifications previously identified in an earlier phase of the life cycle. An appropriate preliminary conceptual design, is responsive to user requirements for the system and associated technical system specifications. Rapid prototyping of the conceptual design is often useful as one way of achieving an appropriate conceptual design. 上午 4時 12分 2022 SYSTEMS ENGINEERING 43 (2) LifeCycle Phases of Systems Engineering The ultimate desired product of this phase of activity is a set of detailed design and architectural specifications that should result in a useful system product. There should exist a high degree of user confidence that a useful product will result from detailed design, or the entire design and development effort should be redone or possibly abandoned. Another product of this phase is a refined set of specifications for the evaluation and operational deployment phases of the life cycle. In the third phase, these are translated into detailed representations in logical form, or physical architecture form, such that system development may occur. A product, process, or system is produced in the fourth phase of the life cycle. This is not the final system design, but rather the result of implementation of the design that resulted from the conceptual design effort of the last phase. User guides for the product should be produced such that realistic operational test and evaluation can be conducted in the next phase. 上午 4時 12分 2022 SYSTEMS ENGINEERING 44 (2) LifeCycle Phases of Systems Engineering Evaluation of the detailed design and the resulting product, process, or system is achieved in the sixth phase of this sevenphase systems engineering life cycle. 上午 4時 12分 2022 SYSTEMS ENGINEERING 45 (2) LifeCy