形状模型在混合建模环境中的映射研究

混合建模技术是ＣＡＤ研究继承参数化特征建模技术之后的又一研究热点,线框,曲面和实体模型３种模型间的转换是混合建模技术的核心,本文介绍了：１）实体模型到线框和曲面模型的映射;（２）线框模型到实体模型的映射,３）曲面框型到实体模型的映射,为混合建模技术做了一些有益的探讨,并将模型映射算法成功地应用于ＩＧＥＳ和ＳＴＥＰ的前后置处理器的设计中,取得了满意的结果。     

基于NURBS的雕塑实体造型系统

本文介绍了一个基于ＮＵＲＢＳ精确表达的雕塑实体造型系统──ＳＣＡＤ１．０，该系统采用曲面模型和实体模型相统一的雕塑实体模型，扩大了造型覆盖城。用ＮＵＲＢＳ精确表达二次曲面和自由曲面，使整个系统具有一致的数学模型。该系统具有较强的造型功能，基本上满足了工程实际的需要。另外，ＳＣＡＤ１．０还有曲面ＮＣ加工的干涉检验和轨迹仿真等功能。     

基于NURBS的雕塑实体造型系统

本文介绍了一个基于ＮＵＲＢＳ精确表达的雕塑实体造型系统－－ＳＣＡＤ１．０，该系统采用曲面模型和实体模型相统一的雕塑实体模型，扩大了造型覆盖城。用ＮＵＲＢＳ精确表达二次曲面和自由曲面，使整个系统具有一致的数学模型。该系统具有较强的造型功能，基本上满足了工程实际的需要。另外，ＳＣＡＤ１．０还有曲面ＮＣ加工的干涉检验和轨迹仿真等功能。     

用任意一个基求可行基与基本可行解的算法

用任意一个基求可行基与基本可行解的算法陈开周，郭强（西安电子科技大学）ＡＮＡＬＧＯＲＩＴＨＭＯＦＦＩＮＤＩＮＧＡＦＥＡＳＩＢＬＥＢＡＳＩＳＡＮＤＡＢＡＳＩＣＦＥＡＳＩＢＬＥＳＯＬＵＴＩＯＮＷｆＴＨＡＮＹＢＡＳＩＳ￥ＣｈｅｎＫａｉｚｈｏｕ；ＧｕｏＱｉａ...     

COLLISION DETECTION AMONG MOVING OBJECTSIN MACHINING PROCESS SIMULATION

ＣＯＬＬＩＳＩＯＮＤＥＴＥＣＴＩＯＮＡＭＯＮＧＭＯＶＩＮＧＯＢＪＥＣＴＳＩＮＭＡＣＨＩＮＩＮＧＰＲＯＣＥＳＳＳＩＭＵＬＡＴＩＯＮＹａｎｇＨｅｍｉｎｇ；ＬｕＡｎｓｈｅｎｇ；ＺｈｏｕＪｉＣＯＬＬＩＳＩＯＮＤＥＴＥＣＴＩＯＮＡＭＯＮＧＭＯＶＩＮＧＯＢＪＥＣ...     

An Arbitrary Triangular Bezier Sudivision Slgorithm and its Applications

ＡＮＡＲＢＩＴＲＡＲＹＴＲＩＡＮＧＵＬＡＲＢＥＺＩＥＲＳＵＢＤＩＶＩＳＩＯＮＡＬＧＯＲＩＴＨＭＡＮＤＩＴＳＡＰＰＬＩＣＡＴＩＯＮＳＬｕＸｉａｏｌｉｎ；ＭａＬｉｚｈｕａｎｇ；ＨｅＺｈｉｊｕｎＡＮＡＲＢＩＴＲＡＲＹＴＲＩＡＮＧＵＬＡＲＢＥＺＩＥＲＳＵＢＤ...     

MCS－51单片机与微机通用并行接口（GPIB）通讯的实现

ＧＰＩＢ接口即ＩＥＥＥ－４８８接口标准，是一种通用８位并行接口，广泛应用于工业控制和自动测试系统。本文介绍了基于ＭＣＳ－５１单片机的ＧＰＩＢ接口的实现方法，并详细介绍了软件与硬件的设计。     

CURVE AND SURFACE INTERPOLATIONBY SUBDIVISION ALGORITHMS

ＣＵＲＶＥＡＮＤＳＵＲＦＡＣＥＩＮＴＥＲＰＯＬＡＴＩＯＮＢＹＳＵＢＤＩＶＩＳＩＯＮＡＬＧＯＲＩＴＨＭＳＲｕｉｂｉｎＱｕＣＵＲＶＥＡＮＤＳＵＲＦＡＣＥＩＮＴＥＲＰＯＬＡＴＩＯＮＢＹＳＵＢＤＩＶＩＳＩＯＮＡＬＧＯＲＩＴＨＭＳ￥ＲｕｉｂｉｎＱｕＡｂｓｔｒａ...     

基于方块脉冲函数逼近的线性连续回归模型的参数估计及其应用

基于方块脉冲函数逼近的线性连续回归模型的参数估计及其应用赵明旺（武汉钢铁学院）ＰＡＲＡＭＥＴＥＲＥＳＴＩＭＡＴＩＯＮＦＯＲＬＩＮＥＡＲＣＯＮＴＩＮＵＯＵＳＲＥＧＲＥＳＳＩＶＥＳＹＳＴＥＭＳＶＩＡＢＬＯＣＫＰＵＬＳＥＦＵＮＣＴＩＯＮＳＡＮＤＩＴＳＡＰＰ...     

在专用网上实现的中西文兼容Videotex终端的设计

在专用网上实现的中西文兼容Ｖｉｄｅｏｔｅｘ终端的设计任伟利（西安交通大学信息与控制工程系西安７１００４９）ＤＥＳＩＧＮＯＦＣＯＭＰＡＴＩＢＬＥＣＨＩＮＥＳＥ－ＥＮＧＬＩＳＨＶＩＤＥＯＴＥＸＴＥＲＭＩＮＡＬＢＡＳＥＤＯＮＳＰＥＣＩＡＬ－ＰＵＲＰＯＳＥＮ...     

Automesh for trimmed surface entity of IGES/PDES

IGES/PDES is an internationally accepted standard protocol for transferring the information of a two-dimensional or three-dimensional model between different CAD/CAM software. Any solid model can be constituted by a number of surfaces. Trimmed surface is one of the most important entities used to design a two-dimensional or three-dimensional model in IGES/PDES. The main idea in this article is to extract trimmed surface entity information from an IGES protocol created in a CAD/CAM software. Then, from the extracted information of trimmed surface entity in the model space and in the u–v space, a new u–v space is developed for meshing. After meshing the geometric region in the new u–v space, the meshed geometric region is transformed back to the model space by using a particular transformation. A Fortran code which can be used for pre-processing in Boundary Element Method has been developed by the present authors. Some meshed surface models are presented in this paper as examples.     

Importing mesh entities through IGES/PDES

IGES/PDES is an internationally accepted standard for transferring solid model information between different CAD/CAM software. Most of the information, like geometric entities, mesh entities and drafting entities, for a model generated in a particular software may be imported into another software through the IGES protocol, although either software may have its own internal database structure, radically different from each other. The goal of this article is to outline the basic concepts involved in extracting relevant information from an IGES file produced by a CAD/CAM software. In order to elucidate the process involved, only the mesh entities (nodes and elements) are brought in and a simple F77 code is attached, which could easily be extended to develop a general purpose IGES translator for pre-processing in a Finite Element/Boundary Element based analysis environment.     

虚拟加工中工件毛坯模型的建立

为解决虚拟加工中工件毛坯模型的识别问题,提出对规则形状工件毛坯采用OpenGL建模、对复杂形状工件毛坯采用美国初始图形交换规范（Initial Graphics Exchange Specification,IGES）文件进行模型数据转换的方法.该方法利用CAD软件为工件毛坯进行三维造型,生成IGES文件,然后在虚拟加工环境下读取IGES文件并生成工件毛坯模型,从而实现工件毛坯模型在新环境中的建立.经过建立具体的工件毛坯模型,验证相关理论的正确性,为在虚拟加工环境下工件毛坯模型的建立提供可行的依据.     

IGES Model Comparison System: A Tool for Tsting and Validating IGES Processors

The IGES Model Comparison System (IMCOS) is the first test tool to allow an easy and automatic semantic comparison of CAD models represented in IGES format. By systematically analyzing and comparing entity data and structures of generated and exchanged IGES models, it detects loss of information and functionality resulting from model exchange via IGES processors. IMCOS was designed and implemented as a tabledriven IGES processor to allow external control of the comparison process and full coverage of the current version of IGES (Version 3.0) and future versions. This article presents the basic concepts of IMCOS. The great interest in and discussion of IMCOS have shown the importance of such a test tool. IMCOS may be used as one of several test tools within an overall IGES verification program.     

逆向工程中IGES数据接口的实现

逆向工程是当前先进制造技术研究的热点之一,通过对IGES标准及曲面实体数据的结构分析,进行逆向CAD软件的IGES接口设计,实现逆向软件与通用CAD造型软件之间曲面数据转换。     

基于IGES接口的电磁计算模型数据交互

现今武器大多是利用非均匀有理B样条(non-uniform rational B-spline,NURBS)数学表述,在CAD/CAM系统下完成建模和重构.利用电磁计算软件运算武器模型的雷达散射截面(radar cross section,RCS)从而评估其隐身性能,就需要与CAD/CAM系统进行数据交互.通过对基本图形转换规范(initial graphics exchange specification,IGES)数据标准的分析,为电磁计算软件编译了IGES数据接口.该数据接口具备IGES文件数据导入和模型数据导出另存为IGES文件格式的功能,从而实现了自行开发的计算软件CRCS v1.2和CAD系统软件的数据交互,提高了软件处理复杂模型的能力进而使模型重构与计算趋于一体化.     

基于B-Rep实体模型的IGES转换为STL

提出一种将IGES文件格式转换成STL文件格式的算法.根据IGES文件内容重构几何实体信息及其拓扑关系;将几何实体的三维曲面贴合为二维平面,并将曲面上的轮廓边界转换到平面上,在二维空间中根据封闭轮廓边界裁剪曲面;根据曲面上保留的特征点及轮廓边界上的顶点信息对面进行符合STL模型一致性规则的三角剖分,生成合法的STL文件.该算法的核心是保证面与面接合处的三角化的正确性.最后介绍了该算法的转换实例.     

基于工业CT切片数据的CAD模型重构

为了使工业CT（computed tomography）扫描获得的切片数据能够被CAD软件直接处理并进行模型重构，在得到切片轮廓点坐标数据的基础上，提出了用IGES（Initial Graphics Exchange Specification）格式作为边缘轮廓坐标数据和CAD软件交换标准的方法，并采用VC^＋＋设计了IGES格式转换软件。实现了IGES格式文件的生成，并用逆向软件Imageware重构出三维CAD模型，取得了较好的效果。