设计过程中设计意图维护和拓扑元素命名

拓扑元素的命名和辨识是基于历史的参数化特征造型中的一个关键问题,其实质是维护设计过程中隐含的设计意图.通过分析设计过程与拓扑元素命名的内在关系,面向隐含设计意图捕获,给出了设计过程中拓扑元素变动类型及其被引用元素辨识要求;提出了面的有向等参线概念和基于有向等参线的面面连接关系,以面为核心,综合拓扑元素的局部拓扑信息和几何特性进行拓扑元素命名;将拓扑元素相邻面分成活化面集和非活化面集,基于没计变动连续性观察.将隐含设计意图通过拓扑元素相关面集的子集关系表达出来,提出了拓扑元素辨识的子集关系原则.实验验证表明,文中方法能够更有效地处理拓扑结构发生变化的情况.     

一种拓扑元素的命名和辨识方法

在基于历史的参数化特征造型系统中,拓扑元素的命名和特征模型重新生成时拓扑元素的正确辨识是一个关键问题。该文提出了一种拓扑元素命名和辨识的新方法,此方法基于两个新概念－－影响特征和影响面,通过检查被引用元素和被辨识元素间的影响特征集、影响面集以及非影响集是否存在子集关系进行拓扑元素的辨识,其主要创新点在于依据导致一拓扑元素产生和产生变化的特征和特征面的信息进行拓扑元素辨识。该方法的主要优点是在特征模型编辑后物体的拓扑结构发生变异时能够更合理地辨识出设计历史中的引用拓扑元素。     

支持协同CAD的拓扑实体永久命名机制

在特征参数化定义域直接引用B-Rep域中的拓扑实体是以往永久命名方法固有的缺陷。提出了基于特征的解决方案：为特征面建立统一的命名方法,并规定在建模过程中特征面的名字不变;建立拓扑实体与特征面之间的表达关系,在特征参数化定义过程中引用由特征面表达的拓扑面,解决基于特征的协同CAD中拓扑实体永久命名问题;给出提出参考面的概念,用于解决拓扑面、拓扑边分裂和多重交线等问题引起的引用模糊问题。在此基础上,详细讨论了拓扑面、拓扑边匹配的方法。     

一种钣金件拓扑元素命名和辨识方法

拓扑元素的命名与辨别是特征技术中存在的一个困难和待解决的问题.本文在对钣金件特征研究和"零厚度"假设的基础上,提出了一种钣金件拓扑元素命名和辨别的新方法.该方法采用元素编号的方法对拓扑元素进行命名,并根据钣金件的拓扑点和拓扑边编号与旧模型中的编号是否一致来辨识点和边的拓扑元素.实验表明该方法在钣金件的拓扑结构发生变化时能有效地辨识出拓扑元素的前后对应关系.     

拓扑元素的命名机制研究综述

在基于历史的参数化特征造型系统中,拓扑元素的命名和特征模型重新生成时拓扑元素的正确辨识是一个关键问题。此文基于参数化系统的模型表示方法,探讨了拓扑元素永久命名问题,分析了解决该问题的4个基本条件及其内在关系,将拓扑元素永久命名问题分为唯一命名及其辨识问题和模型重建阶段拓扑结构发生改变时的语义辨识问题2个层面展开研究,并对其他相关研究中的名字问题进行了概述。     

基于原始面命名的相交特征快速判别方法

针对特征技术研究和应用中的特征相交问题,提出了一种判别特征是否相交的方法。该方法基于特征原始面命名机制,以几何模型中的拓扑边为核心,通过检查拓扑边的两个相邻面的名称属性的构成特点,并结合几何模型中的拓扑边与特征体中相应原始面之间以及不同特征体的原始面之间的拓扑关系实现特征相交关系的判断。该方法不但能够正确地判别出相交特征,而且通过一系列的原始面名查找来代替在特征体间作布尔运算进行相交特征判别,从而有效提高了判别速度。     

改进快速全局滑模控制方法

针对全局滑模控制的动态滑模面不能在有限时间内演化为线性滑模面的缺点, 提出一种改进的全局滑模控制方法, 其动态滑模面的衰减函数由3个指数函数项组成一阶可导函数, 并能在有限时间内衰减为零. 这样, 该方法不仅具有了全局滑模控制的全局鲁棒性, 而且能够使动态滑模面在有限时间内演化为线性滑模面, 从而加快了系统的响应速度. 利用该方法实现了二阶电力系统的混沌控制, 仿真结果验证了所提出方法的有效性.     

基于轨面辨识的电力机车粘着控制仿真研究

针对避免因轨面粘着条件变化而造成车轮空转,提出了基于模糊理论的轨面辨识控制方法,将实时蠕滑速度和全维状态观测器实时估计,并利用粘着系数通过模糊逻辑推理判断的当前轨面与标准轨面的相似度,快速、准确地辨识出当前轨面的粘着峰值点.最后通过对牵引电机的输出转矩动态调整,以实现充分利用当前轨面轮轨间接触力的目的.在MATLAB/Simulink中建立四轴电力机车模型进行仿真研究.仿真结果表明:基于模糊理论的轨面辨识粘着控制方法有效的防止了车轮空转,提高了列车运行的稳定性和铁路运输效率.     

拓扑元素永久命名综述

从参数化系统的模型表示方法出发,分析了拓扑元素永久命名问题,探讨了解决该问题的4个基本条件及其内在关系.将拓扑元素永久命名问题分为唯一命名及其辨识问题和模型重建阶段拓扑结构发生改变时的语义辨识问题2个层面展开综述.其中,第一个层面涉及到原始名字和边界模型的关联,引用名字的构造2个问题;在第二个层面中,按照所引用的信息类型分为引用拓扑对象的几何信息和拓扑对象本身2种处理模式.对其他相关研究中的名字问题进行了概述.最后对今后研究方向进行了探讨.     

基于半边结构的STL文件快速拓扑算法

针对三维模型转换为STL文件后会丢失三角面间的拓扑关系,在对STL格式文件进行读取和分析时,提出了一种基于半边结构和哈希表的快速拓扑重构算法。在读取数据过程中,通过哈希表建立无重复位置信息的点表,并在其中维护一个未添加邻接面的半边集合。依据该集合和拓扑算法完善面的拓扑关系,实现在读取数据的过程中快速建立面的拓扑关系。     

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.