基于结构预映射的产品建模

零件建模和装配建模是产品建模的两个方面,对制造企业的竞争力有重要影响。在当前的计算机辅助设计系统(Computer-aided design,CAD)中,尽管两者已高度集成,它们在过程层面仍然存在相互割裂的现象。为此,提出一种基于结构预映射(Structure pre-mapping,SPM)的产品建模方法。首先对产品建模过程及SPM进行系统分析,明确实现SPM需要完成的主要任务;其次,详细阐述SPM的内涵,并对其进行形式化定义,以便于在CAD系统中描述;第三,基于前期发展的装配特征偶概念,对存在于设计者头脑中的设计意图(表现为抽象配合结构和配合行为)进行系统建模,形成实现SPM的基础;第四,提出基于SPM的产品建模原理,进而展示相应的框架,并分析框架的功能模块及其实现方法;最后,通过HP发动机空气过滤器头部组件的产品建模实例论证方法的可行性。该方法可在过程层面上提高产品建模的集成程度,对于现有CAD建模理论和技术体系的丰富和发展有一定的积极意义。

Study on Pests Forecasting Using the Method of Neural Network Based on Fuzzy Clustering

Aimed to the characters of pests forecast such as fuzziness, correlation, nonlinear and real-time as well as decline of generalization capacity of neural network in prediction with few observations, a method of pests forecasting using the method of neural network based on fuzzy clustering was proposed in this experiment. The simulation results demonstrated that the method was simple and practical and could forecast pests fast and accurately, particularly, the method could obtain good results with few samples and samples correlation.