非均质材料零件的CAD与产品数字化

非均质材料零件是指零件的细微组织结构具有类似于生物体结构的二维或三维梯度功能,从而实现材料组织与零件形状的最佳组合,共同实现零件的功能和性能。这正合乎可持续发展战略需求。 产品数字化是指将零件的形状信息、表观信息、材料组织信息、制造信息和功能信息统一管理,进行完全的数字化描述,并建立这些信息的物理模型,以支持产品并行设计制造和全生命周期信息共享。 目前,产品数字化建模技术主要有线框建模、曲面建模、实体建模和特征建模等。然而这些建模手段以描述产品形状特征为主,仅限于均质材料零件的数字化,难以描述零件…     

RTL级模拟矢量自动生成设计化简方法研究

提出一种Verilog程序切片算法，给出了该算法的正确性证明的理论框架；并利用提出的Verilog程序切片算法对Verilog RTL级设计进行化简，实现模拟矢量自动生成状态化简目的，实验结果表明：该算法对状态化简效果非常明显，可以有效地解决状态空间爆炸问题。     

基于三坐标测量机的曲面零件逆向设计研究

逆向工程也称反求工程,是对现有三维实物(样品或模型),利用三维数字化测量设备准确、快速测得轮廓的几何数据,并加以建构、编辑、修改生成通用输出格式的曲面数字化模型,从而生成三维CAD实体数模、数控加工程序或快速原型制造所需的模型截面轮廓数据。介绍了逆向设计,以波轮零件为例,分析了曲面零件特征,说明了应用三维CAD软件建立零件模型过程和方法,论述了基于三坐标测量机的曲面零件的逆向设计和验证过程。     

基于局部功能完备化组合的零件特征结构合成方法

针对传统CAD系统通过人机交互的方法设计零件的特征结构，自动化程度较低，并且不利于完整记录设计依据的问题，提出一种根据功能要求和功能固有关系自动生成记有设计依据的零件特征结构模型的方法．根据零件与其他零件的界面功能，以及设计知识库中定义的零件子功能之间的固有关系，通过引入若干中间子功能，生成完备的零件功能依赖图；在功能依赖图的基础上，根据功能与局部特征结构的映射关系，合成用特征依赖图表示的零件整体特征结构；并由特征依赖图生成能被现有CAD接受的、表示该零件特征结构的参数化CSG模型．     

基于Internet的快速成形工艺选择决策支持系统的设计与实现

本文提出了一种基于网络化的快速成型工艺选择决策支持系统．针对该决策问题中多方案、多目标的特点，建立了指标体系，提出了使用最小加权均方差法实现多目标优化．为考虑零件几何特征对工艺指标的影响，建立了表达零件几何特征映射关系的产生式规则库，并用数据库管理系统实现对数据库和知识库的统一管理和维护．本文设计和实现了该系统的网络结构和功能，通过Web平台将用户、专家和服务中心联结起来，并论述了其中所采用的网络技术．通过一个应用实例说明了优化算法和系统的运作过程．     

基于功能特征的零件建模技术

本文研究了一种人有人工智能性质的，以广义功能特征为对象的体特征模型定义方法，用该方法建立箱体零件信息模型，实现了箱体功能与箱体几何特征之间的映射，并在满足箱体功能的要求下实现箱体的几何设计与工艺设计交叉进行。     

Delcam正在研发面向金属零件增材制造的软件PartBuilder

2016年3月，Delcam宣布正在研发一款面向金属零件增材制造准备的软件PartBuilder。PartBuilder目前仍处于开发阶段，Delcam Birmingham英国总部正在加速其研发工作。PartBuilder基于Delcam PowerSHAPE开发，专门用于3D打印制造中CAD模型的加工准备。PartBuilder包含了模型准备中的4个主要步骤，包括：检查CAD模型的质量，修复可能存在的问题；将零件定位在便于逐层制造的最佳操作位置；增加额外需要的夹具、支撑和其他几何结构，确保制造可靠性和便于后处理；以适当文件输出处理完成的数据。     

箱体零件的功能特征模型定义方法研究

本文基于零件结构功能分解，研究了以功能特征为对象的箱体特征模型定义方法。用该方法建立箱体零件信息模型，实现了箱体结构功能与箱体几何特征之间的映射，并在满足箱体功能要求的前提下实现箱体的并行设计过程。     

基于几何形状相似性的工艺实例检索

提出一种基于匹配零件几何形状的工艺实例检索方法．根据B-Rep实体表示法，构造形状向量邻接矩阵（FVAM）以表达零件几何形状，并给出了基于FVAM的工艺实例模型形式化定义；通过抽取表征FVAM的特征参数建立了一个有效的实例索引机制，研究了形状相似性及实例相似性的计算方法；最后给出了工艺实例检索过程的算法实现．该方法具有较好的通用性和实用性，已在具体应用中验证了方法的可行性．     

网络化工艺分工规划系统的研究

动态联盟企业面向复杂零件的工艺分工规划问题是网络化制造中的一个关键问题。针对该问题，提出了逻辑制造单元的概念，通过它在工艺分工规划和制造资源之间建立联系，研究了基于逻辑制造单元的制造资源能力建模、逻辑加工路线设计，以及面向逻辑加工路线的制造资源预配置和优化配置。最后针对复杂零件的制造，进行了基于制造资源优化配置的工艺分工规划系统体系结构设计，并给出了工作流程。     

3D打印模型切片及路径规划研究综述

3D打印包括建模、分层切片、路径规划及打印等过程。对3D打印中三维模型数据处理技术核心--切片和路径规划进行综述。介绍3D打印切片软件中针对单材料不同格式的模型切片处理方法,阐明了3D打印中的不同工艺参数影响下的切片算法,包括各类分层切片算法和扫描填充算法,说明每种算法的优缺点,并对现有的单相均质模型切片算法进行对比分析与评价,总结模型切片处理算法的不足,提出改进方向以及未来研究多材料3D打印模型数据处理的切入点。     

基于XML的DNA公共数据模型

针对目前DNA数据组织与处理中存在的数据异构问题,提出一个基于XML的DNA公共数据模型（DCDM）。该模型具有很强的可扩展性,能克服一般公共数据模型的作用范围小的缺点,可用于构建DNA研究领域统一的DNA数据描述模式。实验结果表明,该模型能解决DNA数据异构中的语义异构。     

梯度负泊松比蜂窝材料的冲击动力学性能分析

借助非线性有限元程序LS-DYNA,基于功能梯度材料的概念,改变蜂窝胞壁厚度,建立了具有密度梯度的内凹六边形负泊松比蜂窝材料模型.分析对比了均匀负泊松比蜂窝材料和梯度负泊松比蜂窝材料在不同面内冲击速度下的变形模式、动态响应和能量吸收特性.研究表明,梯度负泊松比蜂窝材料的动态响应和能量吸收能力受梯度、胞元内凹角度和冲击速度的影响.如果能适当选取各项参数,就可使材料在降低初始应力峰值的同时保持良好的能量吸收能力.因此,具有密度梯度的负泊松比蜂窝材料在结构防护方面具有良好的应用前景.     

CAD modeling for the components made of multi heterogeneous materials and smart materials

There appear more critical requirements for special functions of components/products in various areas, which can be satisfied only by using heterogeneous materials and/or smart materials. The heterogeneous materials include composite materials, functionally graded materials, and heterogeneous materials with a periodic microstructure. To design and manufacture the components made of these materials, the computer models for representing them need first to be built so that further analysis, optimization and manufacturing can be implemented based on the models. This paper develops such a modeling method, which can be implemented by employing the functions of current CAD graphic software and obtain the model that includes all the material information (about periodic microstructures, constituent composition, inclusions, and embedded parts) along with geometry information in 3D solid modeling without the problem arising from too much data.     

激光直接制造和再制造中的三维CAD模型直接分层技术

在分析SolidWorks软件平台下CAD模型数据的内部表达方法以及拓扑信息和几何信息提取方法的基础上,研究三维CAD模型直接分层技术.对SolidWorks进行二次开发,调用SolidWorks应用程序接口函数中的曲面一曲面求交函数对CAD模型曲面与分层平面求交,得到的交线首尾相连形成轮廓轨迹;同时研究了光栅填充扫描算法及程序实现.为实现切片数据的通用化,设计了记录切片数据的文件格式,用直线、圆弧或圆描述分层轮廓.对上述的直接分层不仅进行了软件模拟,还用于直接制造.制作的试件与STL间接分层试件比较结果表明,采用直接分层的试件的精度和表面质量优于STL间接分层.     

Analysis of peer learning behaviors using multiple representations in virtual reality and their impacts on geometry problem solving

Learning geometry emphasizes the importance of exploring different representations such as virtual manipulatives, written math formulas, and verbal explanations, which help students build math concepts and develop critical thinking. Besides helping individuals construct math knowledge, peer interaction also plays a crucial role in promoting an understanding of mathematics and geometric problem solving. In this research, an Interactive Future Mathematics Classroom (IFMC) based on the Collaborative Virtual Reality Learning Environment (CVRLE) was proposed to facilitate three-dimensional (3-D) geometric problem solving. Two representational tools, the virtual manipulative and a white board, were integrated into the IFMC to help students with the following activities: to synchronously review peers' solving processes; to individually or collaboratively manipulate 3-D objects using the virtual manipulative; and to give comments on peers' white boards for future queries and discussions. One eight-week experiment was conducted and the results showed that the experimental group using the IFMC performed significantly better than the control group on geometric learning achievement. Further analysis showed that the peer learning behaviors of the experimental group in the two kinds of geometric problems, volume and surface area calculation, were different due to the problems' varying difficulty levels. Moreover, various peer learning behaviors with multiple representations lead to different types of strategies for geometric problem solving in the IFMC. Therefore, peer learning behaviors in the IFMC were found useful to facilitate geometric problem solving by sharing ideas and exploring multiple representations.     

An adaptive web page layout structure for small devices

The limited display size of current small Internet devices is becoming a serious obstacle to information access. In this paper, we introduce a Document REpresentation for Scalable Structures (DRESS) to help information providers make composite documents, typically web pages, scalable in both logic and layout structure to support effective information acquisition in heterogeneous environments. Through this novel document representation structure based on binary slicing trees, the document can dynamically adapt its presentation according to display sizes by maximizing the information throughput to users. We discuss the details of this structure with its key attributes. An automatic approach for generating this structure for existing web pages is also presented. A branch-and-bound algorithm and a capacity ratio-based slicing method are proposed to select proper content representation and aesthetic document layouts respectively. A set of user study experiments have been carried out and the results show that compared with the thumbnail-based approach, the DRESS-based interface can reduce browsing time by 23.5%. This work was performed when the second and the third authors were visiting students at Microsoft Research Asia.     

基于复合梯度向量的人脸识别算法

提出了一种新的基于复合梯度向量(Composite gradient vector, CGV)描述的人脸识别算法. 该算法首先在定位后的人脸图像中标定目标区域, 并在目标区域内划分特征子区域, 然后,以特征子区域的边缘奇异点作为向量的起点和终点进行正交采样得到基向量, 将目标区域内所有基向量组建向量簇, 通过对基向量的多维复合得到向量簇内所有极大梯度向量, 最后,以极大梯度向量作为元素组建复合梯度向量并统计复合梯度向量的维度和梯度信息, 将复合梯度向量、复合梯度向量维度和梯度进行人脸库对比, 识别出人脸身份. 该算法抓住了人脸面部特征分散性的特点, 继而对分散性特征采用具有连续性规律约束的复合梯度向量进行描述识别. 实验结果表明, 该算法克服了特征域旋转、光照强度变化及多姿态、多表情对人脸识别的影响, 具有速度快、识别准确、适应性强的特点.     

Static and Dynamic Slicing of Constraint Logic Programs

Slicing is a program analysis technique originally developed for imperative languages. It facilitates understanding of data flow and debugging.This paper discusses slicing of Constraint Logic Programs. Constraint Logic Programming (CLP) is an emerging software technology with a growing number of applications. Data flow in constraint programs is not explicit, and for this reason the concepts of slice and the slicing techniques of imperative languages are not directly applicable.This paper formulates declarative notions of slice suitable for CLP. They provide a basis for defining slicing techniques (both dynamic and static) based on variable sharing. The techniques are further extended by using groundness information.A prototype dynamic slicer of CLP programs implementing the presented ideas is briefly described together with the results of some slicing experiments.     

An Inexact Newton-CG-Type Active Contour Approach for the Minimization of the Mumford-Shah Functional

The problem of segmentation of a given gray scale image by minimization of the Mumford-Shah functional is considered. The minimization problem is formulated as a shape optimization problem where the contour which separates homogeneous regions is the (geometric) optimization variable. Expressions for first and second order shape sensitivities are derived using the speed method from classical shape sensitivity calculus. Second order information (the shape Hessian of the cost functional) is used to set up a Newton-type algorithm, where a preconditioning operator is applied to the gradient direction to obtain a better descent direction. The issue of positive definiteness of the shape Hessian is addressed in a heuristic way. It is suggested to use a positive definite approximation of the shape Hessian as a preconditioner for the gradient direction. The descent vector field is used as speed vector field in the level set formulation for the propagating contour. The implementation of the algorithm is discussed in some detail. Numerical experiments comparing gradient and Newton-type flows for different images are presented.