4. The System Engineering Process

The system engineering process is the means for accomplishing the requirements allocation in a way that coordinates all design disciplines. The purpose of such coordination is to make sure that the design requirements are allocated and implemented in the design so as to achieve an optimum design solution with respect to system performance capability, unit production cost, and operating and support costs.This process is directly concerned with achieving a best-value design solution. To achieve a best-value solution,both the design requirements and the design solution to those requirements are subject to tradeoffs relating to the cost, schedule, and performance of various alternative designs.

System engineering defines the system on a total basis so that the design will reflect requirements for equipment, computer programs, facilities, procedural data, and personnel in an integrated fashion to meet the particular mission requirements. It provides the source requirement data for.the development of specifications, test plans , and procedures; and the backup data required to define ,contract,design,develop,produce ,install,check out,and test the system.

4. 系统工程方法

系统工程方法是以协调各个设计学科的方式对各项要求进行分配的手段。这种协调工作的目的在于确保将设计要求分配到设计中并使之在设计上得以兑现，以期获得就系统性能、产品单价和运作与保障费用而论是最佳的设计方案。这种方法是与获得最有价值的设计方案直接相关的。为了获得最有价值的设计方案，设计要求与满足这些要求的设计方案两者都须在经过对有关各种可用方案的成本、进度和性能进行权衡考虑之后再定。

系统工程是从总体上确定整个系统的，这样，整个设计才能以满足特定使命要求的综合方式反映对装置、计算机程序、设备、过程数据以及人员等的要求。它既可提供研究编制性能指标、试验计划和步骤的原始要求数据；又可提供定义、承包、设计、研制、生产、装配、检验和测试整个系统所要求的辅助数据。

Figure 1 (omitted here) shows a typical system engineering process for an Air Force aircraft weapon systen. It illustrates the major interrelationships between technical program planning and control and engineering integration.The process begins with military needs,the Air Force system requirements document, technologies applicable to the need, and the specified constraints for the system design. These become inputs to functional analysis,which defines the basic functions the system must perform to accomplish the mission.5This proceeds in an iterative process of system tradeoffs, assessments, and engineering speciality integration to determine system requirements and system selection.

图1（此略〉表示美国空军飞机武器系统研制采用的典型系统工程方法。它表明了技术规划的计划与管理同工程一体化之间的主要联系。这一方法是从军事需要、空军系统要求文件、适合需要的技术以及系统设计规定的制约条件等出发的。这些就成为功能分析的输人数据，通过这种功能分析确定系统实现使命要求所必需的基本功能。具体做法是采用迭代法，经过系统折衷方案、评定和工程专业一体化迭代过程，确定系统要求并筛选系统。

5. Engineering Specialily Integration

Engineering speciality integration involves the timely and appropriate intermeshing of engineering efforts and disciplines to ensure their influences on system design. Engineering speciality areas include reliability,maintainability, logistics engineering, human factors, safety, value engineering, standardization, quality assurance, electromagnetic compatibility, survivability /vulnerability, system security, training,packaging transportability, production engineering, and natural aerospace environmental support.

System Engineering has representatives of all engineering specialities as participating members and contributors to the system engineering process.6As the functional flow analyses are detailed,the planning of the respective engineering organizations is compared to functional requirements to assure complete allocation and planning for all requirements. This assures that no redundant efforts are being planned and further assures that the respective organizations' responsibilities and authorities are properly assigned and implemented. The schedule interrelations are finalized in accordance with timeline analyses to assure that all critical paths are met.

5. 工程专业一体化

工程专业一体化就是及时适当地对工程工作和学科之间的衔接配合进行协调，以保证它们在系统设计中发挥作用。工程专业领域包括可靠性、可维护性、后勤保障工程、人的因素、安全性、价值工程、标准化、质量保障、电磁兼容性、耐久性/易损性、系统保密性、培训、可装配运输性、生产工程和自然宇航环境保障等。系统工程以各工程专业的代表作为系统工程过程的参加成员和研究人员。在详细进行了功能流程分析之。

后，便将相应工程组织的计划同功能要求作对比，以保证对所有各项要求进行全面的分配和计划。此举可保证计划中完全避免重复性工作，进而保证相应组织的责职与权力得以合理分配和实施。进度方面的相互关系根据时限分析的要求最后敲定，从而保证所有重要的过程都能衔接起来。