面向对象知识模型的构建

Constructing object-oriented knowledge model

介绍了面向对象技术设计知识库模式的方法。强调知识模型构建的重点是在表达、验证及推导设计限制条件,而不是传统意义上的数据。设计概念仍沿用类表示,分3个部分:决策参数、表现参数及限制条件。决策参数是从限制条件中抽象出来的数据,代表设计对象的属性或状态;表现参数是对决策参数的计算和度量;限制条件规范及限制表现参数的域值,可视为类不变量,每个类对象都必需满足之。设计概念之间的相互联系则用关联来阐述。传统面向对象技术考虑的是数据在关联中的横向、纵向传递,提出关联类以捕获数据,同时增加关联的限制条件作为关联不变量。在继承和整件-部件关联的基础上,增加了特性关联。模型构建构建以汽车制造中模板设计为例加以说明。

The experience in object-oriented design of an engineering knowledge repository schema are shared. The knowledge mode focuses on the expression, reasoning and validation of design constraints other than data of primitive types by tradition. The basic design concepts are represented with classes consisting of three compartments, namely, decision properties, performance properties and design constraints. Decision properties are derived from constraints and are primitive data representing the status of design objects Performance properties calculate decision properties and the domain are bounded by design constraints. Thus constraints are taken as invariants that every object of the class must satisfy. Associations among design concepts are made explicit to address new variables and new constraints that hold the association. By tradition the object-oriented method addresses the horizontal and vertical propagation of data along the as sociation, hereby association class to accommodate data as well as constraints was proposed, which standed for the association invariants. In addition to the inheritance and Part-Whole relationship, Has-Feature association was proposed. The knowledge repository is illustrated in the context of stamping design knowledge of automobile manufacturing.