A Knowledge-Navigation System for Dimensional Metrology

Geometric dimensioning and tolerancing (GD&T) is a method to specify the dimensions and form of a part so that it will meet its design intent. GD&T is difficult to master for two main reasons. First, it is based on complex 3D geometric entities and relationships. Second, the geometry is associated with a large, diverse knowledge base of dimensional metrology with many interconnections. This paper describes an approach to create a dimensional metrology knowledge base that is organized around a set of key concepts and to represent those concepts as virtual objects that can be navigated with interactive, computer visualization techniques to access the associated knowledge. The approach can enable several applications. First is the application to convey the definition and meaning of GD&T over a broad range of tolerance types. Second is the application to provide a visualization of dimensional metrology knowledge within a control hierarchy of the inspection process. Third is the application to show the coverage of interoperability standards to enable industry to make decisions on standards development and harmonization efforts. A prototype system has been implemented to demonstrate the principles involved in the approach.     

钢结构计算简图中荷载的自动分层标注

文中对钢结构计算简图中荷载的自动标注作了讨论,首先给出了荷载归并算法,以及一些工程规则,在此基础上提出了一种基于荷载方向划分的荷载自动分层标注算法。     

Thermal dilatation in functional tolerancing

Functional tolerancing is classically based onto dimension chains to respect functional requirements. Tolerance synthesis deals with dimensions optimization in order to maximize tolerances. This method is classically used taking into account only geometrical defaults. Mechanisms concerned with significant variation of temperature in different stages of functioning, require taking into account thermal expansion. This expansion has a direct impact onto clearances and dimensions of the mechanism. The purpose of this paper is to consider thermal expansion of parts integrated within functional tolerancing. In particular, this paper will compare the effects of tolerancing, thermal expansion and uncertainties of temperature in order to know if uncertainties must be included in the tolerance chain or can be neglected as second order. A basic experimental mechanism is used to show this method and the differences between the two approaches.     

ET2000服装CAD软件尺寸出错时的调整对策

分析智能化服装CAD软件ET2000系统在打板时容易产生的一些尺寸错误;并研究了合理解决尺寸“出错”问题的调整对策.为使用ET2000系统进行服装CAD教学,找到合理的解决办法,并为软件设计人员提供参考.     

基于无向图的尺寸标注模型的研究

提出了一种基于图结构描述的二维图形尺寸标注模型的建立及存储方法，该方法利用图论的概念和原理，在几何约束系统的基础上用无向图的结构描述尺寸标注模型，同时，建立一种扩展的图的邻接表的数据结构来存储尺寸标注模型。     

古建筑设计中单位换算的研究

分析了古建筑设计中由于古尺的消失和古制单位与计算机绘图单位的不匹配而使得古建筑设计所面临的问题.介绍了各个朝代的尺寸与现在公制单位的关系,提出了将古制单位与计算机绘图相结合的解决方法,特别是分析并例举了常用的宋之"材"、"分0"制和清之"斗口"制在计算机绘图中的处理方法,避免了复杂的人工换算,极大地提高了设计效率.也有利于对年轻的古建筑设计人员的培养.     

基于模板匹配的二维图自动生成算法研究

基于模板匹配的思想,对二维图的自动生成算法进行了研究。首先将模板和待标注三维模型的点、线、面信息以及几何结构和拓扑结构以属性图的数据结构方式进行存储,通过面的广度优先搜索和边的广度优先搜索对存储的2个属性图进行匹配,再读取模板二维图上的标注等信息,利用二维图和三维模型的关联性和属性图匹配结果,对待标注三维模型进行自动标注,包括尺寸标注、表面粗糙度标注、形位公差标注等信息。     

Influence of sintering temperature on the shrinkage and geometrical characteristics of steel parts produced by powder metallurgy

The dimensional and geometrical characteristics of Charpy bars produced with two different steels were investigated to evaluate the effect of increasing the sintering temperature from 1120 °C (conventional sintering temperature) up to 1350 °C. The problem was approached from the Geometric Dimensioning and Tolerancing (GD&T) point of view, referring to the standard ASME Y14.5 (2009). The dimensional and geometrical characteristics were evaluated using a Coordinate Measuring Machine (CMM), measuring the surfaces by scanning mode. The work highlights that the increase in the sintering temperature, aimed at improving the mechanical properties, does not prevent the main benefit of this technology, i.e., the possibility of producing parts with good dimensional and geometrical precision. Moreover, a methodology establishing the measurement procedures and data processing, to be used in future work for the characterisation of more complex shapes, was defined.     

Design and Dimensioning of a WDM Mesh Network to Groom Dynamically Varying Traffic

In this paper, we address the traffic grooming problem in WDM mesh networks when the offered traffic is characterized by a set of traffic matrices—a variant of dynamically changing traffic. We justify the need to address this problem in mesh networks and also argue for the validity of our approach to solve this problem. Our primary objective is to design the network in terms of the number of wavelengths and transceivers required to support any offered traffic matrix. We provide a simple and generic framework to minimize the number of transceivers needed in the network. Simulation results have been presented in contrast with a possible approach, to enable comparison with our solution strategy. An ILP formulation of our approach is also presented.     

Downlink Dimensioning for the HSDPA Standard

We present an analytic derivation of downlink dimensioning for a wireless network employing the High Speed Downlink Packet Access (HSDPA) standard [Moulsley, Conference Publication No. 477, IEE 2001], currently being developed by the 3rd Generation Partnership Project (3GPP) [http://www.3gpp.org] as part of the next stage in the evolution of the WCDMA standard. We determine the maximum possible cell radius such that the probability of outage, P_out, at the cells worst location does not exceed a preset value under full load condition. The results of the paper are presented in the form of curves obtained by numerical integration of integral expressions. The results can be used, for instance, to find the increase in cell radius achievable by a certain reduction in the threshold value of the Signal to Interference plus Noise Ratio (SINR) defining outage.Parts of this work were presented at the 2002 IEEE Wireless Personal Multimedia Communications conference (WPMC), Hawaii.Dan Avidor was born in Tel Aviv, Israel, on October 18, 1936. He received the B.Sc. degree in electrical engineering from the Technion-Israel Institute of Technology, Haifa, Israel, in 1958 and the M.Sc. and Ph.D. degrees in engineering from the University of California, Los Angeles, (UCLA) in 1970 and 1981, respectively. After completing his studies for the Ph.D. degree, he returned to Israel, where he served as a Research and Development Department Head in the Israeli defense forces. He is currently a Distinguished Member of Technical Staff in the Wireless Research Laboratory, Bell Labs, Lucent Technologies, NJ, USA. His current research interests are in adaptive arrays, signal processing, and simulation techniques for wireless systems.Sayandev Mukherjee (M92) was born in Bangalore, India in 1970. He received the Bachelor of Technology degree in electrical engineering from the Indian Institute of Technology, Kanpur, India, in 1991, and the M.S. and Ph.D. degrees in electrical engineering from Cornell University, Ithaca, NY, in 1994 and 1997, respectively. Since 1996, he has been a Member of Technical Staff in the Wireless Research Laboratory, Bell Labs, Lucent Technologies, NJ, USA. His research interests include stochastic models, wireless system simulations, and intelligent resource allocation in wireless systems.