The key techniques of modular design of heavy duty NC mathine tools are described. Amodule definition modelfor modular design and manufacturing of heavy duty NC machine tools isbulit and the essential composition of t...The key techniques of modular design of heavy duty NC mathine tools are described. Amodule definition modelfor modular design and manufacturing of heavy duty NC machine tools isbulit and the essential composition of the module definition model (MDM) is discussed in detail. Itis composed of two models: the part definition model (PDM) and the module assembly model(MAM). The PDM and MAM are built and their structures are given. Using object-oriented know-ledge representation and based on these models, an intelligent support system of modular design forheavy duty NC machine tools is developed and implemented This system has been applied to thepractical use of Wuhan Heavy Duty Machine Tool Works展开更多
Rural tourism in China,has undergone a rapid development in the last three decades.It is an emerging and effective catalyst that promotes industrial restructuring,agricultural development and the upgrading of rural ar...Rural tourism in China,has undergone a rapid development in the last three decades.It is an emerging and effective catalyst that promotes industrial restructuring,agricultural development and the upgrading of rural areas.However,there remains little understanding about the core issues of rural tourism in China:the exact connotation,the principles,the development models and the future directions.This review paper identifies the key issues based on literature analysis,national statistics and press reports to form a general picture of the past,the current and the future prospects of China's rural tourism.The paper firstly addresses the definition,content and principles of rural tourism,and then provides an overview and brief evaluation of the progress and the current development models in China.Finally,based on the analysis of the experiences and problems,the authors sum up with five pathways of the future development of China's rural tourism from the perspective of rural tourism resources,product,market and promotion.展开更多
为减轻人工审查MBD(model based definition)模型尺寸标注的劳动强度,对三维尺寸完备性的自动化审查进行了研究。将尺寸完备性问题归结为对相关几何要素是否定形定位的判断问题,建立了对应约束模型记录约束状态;建立了解析尺寸约束和拓...为减轻人工审查MBD(model based definition)模型尺寸标注的劳动强度,对三维尺寸完备性的自动化审查进行了研究。将尺寸完备性问题归结为对相关几何要素是否定形定位的判断问题,建立了对应约束模型记录约束状态;建立了解析尺寸约束和拓扑约束的约束传播规则,并总结了几何约束的解析算法;针对尺寸缺失造成的约束不足,采用打分策略,并以指定基准或指出尺寸缺失的方式主动添加约束;提出了三维尺寸完备性检查的总体算法。通过对3DDFM原型系统的继续开发,并用三维模型实例验证了方法的有效性。展开更多
The process of designing roundabouts is an iterative process through which, in several checks, the design elements of a roundabout get optimized. Existing regulations for roundabouts involve swept path analyses, sight...The process of designing roundabouts is an iterative process through which, in several checks, the design elements of a roundabout get optimized. Existing regulations for roundabouts involve swept path analyses, sight distance analyses and speed analyses of vehicles passing through the roundabout. Speed analyses are done mostly based on two models, Dutch and American. Each of these two models, in their own way takes into account design elements of the roundabouts, and the US model also envisions the construction of vehicle paths through the roundabout. Main assumption of both models is that vehicle paths through roundabouts consist of few connected radii. US models for path definition takes into account safety distances from marked lines and geometric elements（curbs） at the entrance and exit and through roundabout. Experimentally determined elements of the vehicle path through the roundabout, do not correspond to those recommendations. Comparison of the measured speed at the roundabouts and speed calculated according to aforementioned models at several roundabouts in Croatia, showed a significant difference. An experimental research was conducted as a first step in developing a new model for operating speed through roundabouts. The research aimed to define the basic path elements of vehicle movement in the roundabout at which the maximum speed is achieved. Results of the study are presented in this paper.展开更多
文摘The key techniques of modular design of heavy duty NC mathine tools are described. Amodule definition modelfor modular design and manufacturing of heavy duty NC machine tools isbulit and the essential composition of the module definition model (MDM) is discussed in detail. Itis composed of two models: the part definition model (PDM) and the module assembly model(MAM). The PDM and MAM are built and their structures are given. Using object-oriented know-ledge representation and based on these models, an intelligent support system of modular design forheavy duty NC machine tools is developed and implemented This system has been applied to thepractical use of Wuhan Heavy Duty Machine Tool Works
基金supported by a grant from the major projects of the National Social Science Foundation of China (10zd&051)National Natural Science Foundation Item of China(No.41171435 )from the United Nations(UNDP/CPR/040/SPA)
文摘Rural tourism in China,has undergone a rapid development in the last three decades.It is an emerging and effective catalyst that promotes industrial restructuring,agricultural development and the upgrading of rural areas.However,there remains little understanding about the core issues of rural tourism in China:the exact connotation,the principles,the development models and the future directions.This review paper identifies the key issues based on literature analysis,national statistics and press reports to form a general picture of the past,the current and the future prospects of China's rural tourism.The paper firstly addresses the definition,content and principles of rural tourism,and then provides an overview and brief evaluation of the progress and the current development models in China.Finally,based on the analysis of the experiences and problems,the authors sum up with five pathways of the future development of China's rural tourism from the perspective of rural tourism resources,product,market and promotion.
文摘为减轻人工审查MBD(model based definition)模型尺寸标注的劳动强度,对三维尺寸完备性的自动化审查进行了研究。将尺寸完备性问题归结为对相关几何要素是否定形定位的判断问题,建立了对应约束模型记录约束状态;建立了解析尺寸约束和拓扑约束的约束传播规则,并总结了几何约束的解析算法;针对尺寸缺失造成的约束不足,采用打分策略,并以指定基准或指出尺寸缺失的方式主动添加约束;提出了三维尺寸完备性检查的总体算法。通过对3DDFM原型系统的继续开发,并用三维模型实例验证了方法的有效性。
文摘The process of designing roundabouts is an iterative process through which, in several checks, the design elements of a roundabout get optimized. Existing regulations for roundabouts involve swept path analyses, sight distance analyses and speed analyses of vehicles passing through the roundabout. Speed analyses are done mostly based on two models, Dutch and American. Each of these two models, in their own way takes into account design elements of the roundabouts, and the US model also envisions the construction of vehicle paths through the roundabout. Main assumption of both models is that vehicle paths through roundabouts consist of few connected radii. US models for path definition takes into account safety distances from marked lines and geometric elements（curbs） at the entrance and exit and through roundabout. Experimentally determined elements of the vehicle path through the roundabout, do not correspond to those recommendations. Comparison of the measured speed at the roundabouts and speed calculated according to aforementioned models at several roundabouts in Croatia, showed a significant difference. An experimental research was conducted as a first step in developing a new model for operating speed through roundabouts. The research aimed to define the basic path elements of vehicle movement in the roundabout at which the maximum speed is achieved. Results of the study are presented in this paper.
