复杂三角网格模型刀具组合优化加工研究

在满足复杂三角网格模型数控加工的精度要求下,为提高加工效率,提出了刀具组合优化方法。该方法以刀具轨迹长度最短为目标,并综合考虑模型微分几何信息对加工效率和精度的影响。首先根据面片法矢和曲率将模型分割为多个特征子区域,不同类型的特征子区域采用不同的刀具轨迹生成策略;建立各类型子区域的精确轨迹长度估算模型;选取合适的标准刀具组合并估算轨迹长度,拟合三次B样条曲线,求取曲线一阶导矢得到最小值,选择对应的标准刀具尺寸作为最优刀具尺寸。算法在VC++环境下进行了编程实现和算例验证,结果表明该方法是可行有效的。     

三角网格模型分治加工中区域分割算法的研究

提出分治加工策略以保证复杂三角网格模型数控加工同时具有较高的加工效率和加工精度;针对分治加工的需求,提出一种将机械零件三角网格模型分割成具有加工意义区域的算法。算法采用半边数据结构,基于区域生长原理,以二面角结合刀轴矢量为区域生长的驱动信号,实现了三角网格模型内子加工区域的快速分割。为了避免过分割现象,实现了小区域或误判区域的优化合并处理算法。运行实例表明了该算法能够有效实现加工模型的区域分割。     

基于向量角分线的离散刀轨环子域分割算法

为提高环切加工刀轨质量及生成效率,提出一种基于向量角分线的二维截面轮廓子区域的分割算法.结合Voronoi图的全局分解思想,通过改进中轴线中对多边形凹顶点的不均等处理的拓扑结构,提出有效向量角分线的概念;通过判断向量角分线交点的属性来合并角分线,同时生成子域结点关系树,最终把离散刀轨环分割成隶属于每个边界元素的子区域,并在子区域基础上生成无自交的等距线.实验结果表明,该算法运行高效,可提高刀位轨迹生成的效率和质量,并改善产品的加工性能.     

基于Z-map模型的自由曲面无干涉刀具轨迹生成算法研究

刀具轨迹生成是自由曲面零件数控加工中重要的研究内容.本文分析了自由曲面数控加工中常用的刀具轨迹生成策略和方法,设计和实现了一种基于Z-map结构的自由曲面无干涉刀具轨迹生成算法.本算法采用进化算法进行刀具干涉检测,不仅解决了生成刀具轨迹时因走刀步长不合理而产生的过切问题,而且也确保了生成的刀具轨迹为无干涉刀具轨迹.     

环切区域加工分步式刀具轨迹生成算法研究

与传统的集中式刀具轨迹计算方法不同,基于ＮＣ特征单元,把刀具轨迹计算分为两步完成,以此改善数控加工系统的可集成性,可视性和可控性,给出了抽象ＮＣ特征单元及适合２．５轴区域加工的环切特征单元的定义,提出了通过链接划分法生成环切特征单元,以及通过环切特征单元计算刀具轨迹的算法。     

应用最小生成树实现点云分割

点云分割是点云参数化、形状识别、编辑造型等领域的关键基础算法。提出一种基于最小生成树的点云模型分割算法,包括生成带状分割边界、区域增长、拆分带状分割边界以及生成最终区域4个步骤。算法采用Snake模型提取分割曲线并向两侧扩展形成带状分割边,利用最小生成树实现区域增长来提取区域内部点,最后拆分带状分割边界并与已有区域合并形成最终区域。实验结果表明,该算法能够有效避免过分割和欠分割,能够生成光顺分割边界,与Level Set分割算法相比具有较高的效率。     

基于图模型的道路检测方法

为解决城市环境低速移动机器人的道路检测问题,提出一种基于图模型的道路检测方法.首先,将道路图像划分为子图,计算子图特征向量,生成图模型结点集.然后,提出相近半径概念,计算相近结点边权值,生成图模型边集.在此基础上,采用基于最小生成树的结点合并规则对图模型结点进行合并,实现道路图像分割.最后,通过设置取样窗口,提取道路结点,分割出道路区域.通过实验分析道路检测精度与子图尺寸及阈值参数间的关系,研究采用灰度特征进行道路检测的可行性.实验结果表明,该方法能有效检测出不同类型道路图像中的道路区域,适用于道路检测.     

三维网格的边界强度分割算法

提出一种新的基于网格边界几何信息的快速分割算法,首先按照原始网格模型面片的拓扑关系建立对偶图,并根据网格面片的几何信息设定顶点权和边权;使用k-way 多级分割方法在对偶图上进行快速分割,得到预分割区域以及各分割区域的初始边界;然后定义分割片的特征边界和边界强度函数,用以表示各预分割区域边界上的形变模型;通过最小化形变模型的能量函数,推动初始边界向特征边界运动,最终得到符合最小值法则的有意义的子网格.实验结果表明,该算法快速有效,适用于各种局部边缘特点较显著的三角网格模型.     

对称零空间准则下的LDA特征抽取方法

网格分割在网格参数化、纹理atlas图等几何处理问题中有着重要的应用.提出一种基于顶点或面凸凹信号的简单高效的网格分割算法.基于均匀支撑半径的顶点凸凹信号分析将顶点分为平坦点、凸点、凹点和特征点,先从平坦点进行平坦区域扩展,再从剩下的凸凹点出发进行凸凹区域扩展,最后根据顶点和边界边的光滑度进行区域竞争扩展;对于未能完全分割的简化程度高的模型,基于面的凸凹信号采用类似的过程进一步完成最后的分割.该算法可以快速地进行网格分割并能较好地保持网格特征,特别适用于CAD模型的分割.     

平面域中散乱点的Delaunay三角化算法

基于三角网生长算法和分治算法的思想,提出并实现了一个平面域散乱点的三角网格重构算法.算法首先利用分治算法的思想将散乱点集进行分割,然后在四个极值点确定初始三角形的基础上,基于边的扩展原则构造新的三角形,使网格不断向周围扩展直到所有的待扩展的边全部能构成三角形为止,最终构造出整个散乱点集的三角网格.     

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。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。