基于精密测量的复杂零件的快速反求

本文介绍了一种基于三坐标精密测量的复杂零件的快速反求系统。文中介绍了复杂异型零件从特征点测量、数据读人处理、三维模型重构的一般过程;探讨了测量规划和三维重构的一般规律。     

基于精密测量的复杂零件的快速反求

本文了一种基于三坐标精密测量的复杂零件的快速反求系统,文中介绍了复杂异型零件从特征点测量,数据读入处理,三维模型重构的一般过程,探讨了测量规划和三维重构的一般规律。     

基于混合属性邻接图的MBD模型参数化方法

为解决MBD模型设计变更过程中维护几何信息与技术信息一致性的问题,提出一种MBD模型参数化方法.首先将MBD模型参数化问题分解为几何信息之间、几何信息与技术信息之间以及技术信息之间的参数化问题;其次提出采用混合属性邻接图表达MBD模型中元素间的结构关系和数值关系,通过定义混合属性邻接图中节点和边构建混合属性邻接图;然后提出MBD模型参数化流程,为设计人员生成MBD模型变更决策表.最后以某型号飞机销钉零件为例描述MBD模型参数化方法的过程,验证文中方法的有效性.     

机械加工MBD毛坯模型的特征识别设计方法

为了解决基于模型的定义(MBD)环境下机械加工毛坯辅助设计问题,采用特征识别技术辅助创建三维毛坯模型.首先分析了机械加工工艺设计环节MBD毛坯模型的组成要素与模型要求,并建立零件模型的属性面邻接图;根据零件模型上加工特征的特点划分简单特征、体积特征和表面特征;通过属性面邻接子图的模式从特征集合中识别出简单特征与体积特征,并利用补特征法与半空间法抑制这2种特征;最后,根据工艺员输入的表面加工余量创建抑制表面特征的实体.在整个毛坯设计推理过程中研究了三维制造标注的维护方法,最终达到辅助工艺员快速设计MBD毛坯模型的目的.     

面向三维机加工艺规划系统的CATIA 模型MBD数据提取和应用

在三维CAD领域,随着基于模型定义（Model Based Definition, MBD）技术应用的不断深入, MBD零件设计模型（基于 MBD 设计的三维零件模型）可作为三维机加工艺规划系统的单一数据源,为工艺规划过程设计提供完整的制造信息。制造特征识别是三维机加工艺规划系统的核心技术,是进行工艺规划活动的前提,其基础数据来源于MBD模型的几何信息和非几何信息（MBD数据）。针对汽车、航天等领域广泛使用的CATIA三维模型MBD数据提取的关键技术和难点,介绍如何深入应用CATIA 的CAA二次开发技术提取零件设计模型的MBD数据,并应用于三维机加工艺规划系统的制造特征识别中,为后续的工艺规划过程提供保证。     

产品装配体模型的空间结构相似性检索方法

针对因未考虑装配体空间结构而导致的检索结果不符合预期的问题,提出一种基于空间结构匹配的装配体模型检索方法.在运用空间特征点集表示装配体模型的基础上,提出了基于空间点集匹配方法的装配体相似度算法,综合零件属性相似度、零件空间位置相似度得到了装配体相似度.实验结果证明,该方法能够有效地实现产品装配体的相似性检索.     

基于关键特征相对位置关系的钣金零件检索算法

针对二维钣金类CAD零件相似性的检索,提出一种适用于钣金展开件的相似性检索算法.在分析钣金零件形状特点的基础上,选取设计过程中常用的36种关键特征,建立了关键特征的位置关系模型.该模型以构建关键特征之间的相对位置三角形为基础,具有坐标系无关和旋转无关的特性;以关系模型为依据,提出了钣金件关键特征的相对位置检索算法,并通过实例计算了不同钣金零件之间的相似度.实验结果表明,文中算法是有效的,可满足钣金零件的检索要求,具有实用价值.     

复杂机电产品全三维工艺设计系统研究

针对目前复杂机电产品中高精度、薄壁及异形复杂腔体类零件加工工艺复杂,设 计周期长及后续车间制造检验工人识图不直观等问题,提出并构建了基于MBD 的C/S、B/S 混 合架构全三维工艺设计系统。阐述了系统的体系结构和实施工作流程。详细研究了设计工艺 MBD 模型构建过程中单元信息标识、组合框格标识、三维标注、动态工艺模型构建以及全三维 工艺规程卡构建关键技术。最后,给出了开发与应用实例。研究结果表明,该系统能使设计制 造过程基于统一全三维模型源,有效缩短了传统3D→2D→3D 过程总研制周期,降低了研制成 本。     

MBD机加工序模型更改的主动传播与一致性维护方法

针对MBD机加工序模型在设计更改中数据一致性维护困难的问题,提出了发现、传播与适应MBD工序模型更改的方法.首先归纳了MBD工序模型的组成,分析相邻MBD工序模型之间几何结构与标注的关联关系;接着按照工艺更改情况分类提出工艺更改的传播模型;并基于该传播模型提出了模型更改发现算法、模型更改传播算法和三维标注维护算法,用以维护前后置工序的数据一致性.实例验证结果表明,MBD工序模型的工艺更改传播模型与一致性维护方法是有效的.     

基于锥光偏振全息测量法的自由曲面零件的光学非接触式自动检测

为了解决测量复杂自由曲面零件的速度和精度问题,提出一种基于锥光偏振全息测量方法的自动检测系统.该系统在5自由度自动定位系统的支持下,根据零件的三维CAD模型实现了对自由曲面零件的自动检测.文章介绍了锥光偏振全息测量法的原理,对系统进行了详细描述,讨论了系统基于CAD模型的检测规划及其优化算法,并介绍了相关的自由曲面叶片零件测量的实验结果.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.