讨论了基于模型的系统工程和基于模型的设计的重要性，分析了其建模的差别。分析表明，设计必须在确定的、无歧义的基础上进行，虽然这个结果只能反复迭代得到，否则设计将无法实施。与系统工程建模允许采用某些自然语言相比，设计建模必须严格使用建模语言表达设计的结果。考虑到设计本质上是一个知识流动、集成、竞争和进化的过程，又必须同时满足物质需求、精神需求和社会需求，提出了一组关于设计功能知识分类和表达的建议：用传递函数表达功能单元在量值方面的知识，用由方块、输入向量、输出向量、控制向量和运算符构成的方块图表达功能单元之间的关系。传递函数由功能单元的输入和输出导出。当设计知识在分布式资源环境中由细分和专业化的设计知识服务提供时，确定的、无歧义的行为知识和结构知识表达也往往需要。因此，如何将上述关于功能知识表达的建议与任何系统工程建模语言的任何部分结合起来，确定地、无歧义地表达设计中功能单元或者系统的行为知识和结构知识，将是很有意义的研究。
The importance of MBSE and MBD together with the difference between modelling in systems engineering and modelling in design is discussed. Design has to be carried out on a deterministic and unambiguous base, even it may go through a zig-zag process. In comparison with the modelling in systems engineering which tolerates the use of some natural language, the modelling in design has to adopt modelling language rigidly to express its results. As the design is a process of knowledge flow, knowledge integration, knowledge competitiveness and knowledge evolution, and as it must simultaneously meet the requirement of function on material, the requirement of function on mental and the requirement of function on social, a set of suggestions on classifications and expressions of function knowledge in design are presented as follows. 1) transfer functions are used to express the knowledge of magnitude of function elements; 2) block diagrams formed by blocks, input vectors, output vectors, controlling vectors and operators are used to express the relationship between function elements; 3) transfer functions are derived from inputs and outputs of function elements. When the design knowledge is supplied in a distributed source environment by subdivided and/or specialized design knowledge services the deterministic and unambiguous expressions of behavior knowledge and structure knowledge are sometimes necessary. It is, therefore, meaningful to combine the previous suggestions concerning expressions of function knowledge with any part of any systems engineering modelling language which can determinately and unambiguously describe the behavior and structure of a function element or a system in design.
[1] 谢友柏. 设计科学与设计竞争力[M]. 北京:科学出版社, 2018.
[2] NASA. NASA systems engineering handbook[M]. Washington:NASA Headquarters, 2007.
[3] Jackson S. Systems engineering for commercial aircraft:A domain-specific adaptation[M]. 2nd ed. Surrey:Ashgate, 2015.
[4] 谢友柏. 关于《设计科学与设计竞争力》 的写作[J]. 中国机械工程, 2018, 29(4):499-503.
[5] OMG. OMG systems modelling language(version 1.5)[R/OL]. (2017-05-01)[2018-10-01]. http://www.omg.org/spec/SysML/1.5.
[6] 蒋彩云, 王维平, 李群. SysML:一种新的系统建模语言[J]. 系统仿真学报, 2006, 18(6):1483-1492.
[7] Hirtz J, Stone R B, McAdams D A, et al. A functional basis for engineering design:Reconciling and evolving previous efforts[J]. Research in Engineering Design, 2002, 13(2):65-82.
[8] Stone R B, Wood K L. Development of a functional basis for design[J]. Journal of Mechanical Design, 2000, 122:359-370.
[9] Hirtz J, Stone R B, McAdams D A, et al. A functional basis for engineering design:Reconciling and evolving previous efforts:NIST technical note 1447[R]. Washington DC:US Department of Commerce, 2002.
