Research On Technology And Application Of Engineering Knowledge Granularitilization

Knowledge is of remarkable value as is aware in a long history, especially in solution of engineering problems. Inclusive the bottleneck of knowledge acquirement, the scale of solving problems with knowledge engineering methods is limited for the lack of effective methods of organization and expression of large range different knowledge that's used in solution of complicated problems. This thesis studies on the engineering knowledge in such engineering problems that are widely applied but difficult to solve.The solution of a complicated problem concerns knowledge of different kinds. The relations among different kinds of knowledge constructed through knowledge application in problems solving. Knowledge used in solving similar problems contacts spontaneously and forms a knowledge system. In the thesis, the static structure and dynamic action are considered as two aspects of a knowledge system based on the systematic nature of knowledge. Concepts, properties and methods are proposed for knowledge expressing, organizing, acquiring, improving, applying and managing. Consequently, a complete system describing knowledge is constructed.The solution of a complicated problem is usually divided into several steps other than one. The steps in the solving series are elements of problem solving process programming and problem solving knowledge organizing. In this thesis, relation between problem solving and knowledge application is analyzed, and the elements with increasing relations in problem solving are considered as levels of the knowledge system. In application, the factors taking effect on problem solution is the cause-result relation connotated in knowledge, whatever means the knowledge expressed in. The cause-result relation connotated in knowledge concerns various factors which are cognized in different level. A piece of knowledge connects various factors in different forms in logic, which seems to be a knowledge grain aggregated by various factors. Different knowledge reflects different cause-result relation. The covering range of cause-result relation can be simulated by the dimension of. knowledge grain, i.e. knowledge granularity.Knowledge granularity is analyzed in the thesis, including definition, properties and expression methods.A knowledge granularity is expressed with antecedent, consequent and mapping relations between them. The former component and the later component define by different elements, attributes and constraints.In this thesis, three solving strategies, i. e. level programming, granularity selecting and solution generating are proposed. With introduction of knowledge indexing methods based on matching scale, supporting degree and semantic distance, knowledge reasoning and constraint satisfying are combined to accomplish solution generating and judging. Rules of constraints adjusting and methods of solving back tracing are proposed. Consequently, a comprehensive solving method is presented.A granularity knowledge acquiring method based on task analyzing and an granularity knowledge evolving mechanism of four layers "knowledge data increasing-knowledge elements varying-knowledge granularity varying-knowledge levels adjusting" are proposed.In this thesis, the fractal properties of information connotated in knowledge granularity are disclosed. A fractal coding method with simplified code and complete code relating is proposed to express knowledge.As examples and validations, the expression, organization and application of process planning knowledge based on granularity technology are debated in detail. A process planning system developed based on granularity knowledge technology, i.e. XAC (Xi'an Aircraft Corporation) Process Planning Knowledge Database System is introduced.