求解带状线性方程组的一种并行算法

提出了一种在MIMD分布式存储环境下求解带状线性方程组的交替方向迭代并行算法。利用系数矩阵的结构特点分裂矩阵,使整个计算过程只在相邻处理机间通信两次。给出了系数矩阵分别为Hermite正定矩阵和M-矩阵时算法收敛的充分条件。最后,在HP rx2600集群系统上进行的数值计算表明,该算法与多分裂方法相比具有较高的加速比和并行效率。     

带状线性方程组的并行交替方向算法

提出了分布式存储环境下求解带状线性方程组的并行交替方向迭代算法。充分利用系数矩阵的结构特点,给出了在系数矩阵分别为Hermite正定矩阵和M-矩阵时算法的充分条件,并针对采用的分裂方式,讨论了参数的收敛范围,最后在HPrx2600集群系统上进行了数值计算,结果表明实算与理论相一致,算法简便可行且具有良好的并行性。     

求解块三对角方程组的一种并行策略

提出了一种在MIMD分布式存储环境下求解块三对角线性方程组的并行算法。基于Galerkin原理适当取基构造算法,使整个计算过程只在相邻处理机间通信两次,并给出了系数矩阵为对称正定矩阵时算法收敛的条件。在HP rx2600集群系统上进行的数值计算结果表明该算法与多分裂方法相比具有较高的加速比和并行效率。     

求解块三对角线性方程组的含参并行算法

提出了分布式环境下求解含有两个参数的矩阵分裂方式的一种交替方向迭代并行算法,通过引入两个参数并巧妙分解系数矩阵A得到新算法,从理论上给出了该算法收敛的两个充分条件,并讨论了参数的选择范围.基于局域网的MPI异构环境,在HP rx2600集群上进行了数值实验,并与多分裂方法比较.比较的结果表明,此算法是可行的,具有良好的并行效率.     

求解PageRank的多步幂法修正的广义二级分裂迭代法

本文基于计算PageRank的广义二级分裂迭代算法,提出了多步幂法修正的广义二级分裂迭代方法.首先,我们详细介绍了该算法的计算过程.然后,证明了该算法的收敛性,并讨论了迭代参数的选取.最后,通过数值实验说明该算法具有比广义二级分裂迭代方法更少的计算开销和更快的收敛速度.     

渐进迭代逼近方法的数值分析

基于一类特殊矩阵的幂级数展开,推导了渐进迭代逼近方法和代数插值方法的等价性.在此基础上,针对PIA方法中因病态矩阵而导致收敛速度过慢的问题,通过矩阵QR分解引入变换矩阵,再优化迭代矩阵的谱半径,来加速PIA方法收敛;相对于因不同的参数化而导致计算效率的不确定性问题,采用向心加速参数化、优化配置矩阵来确保计算效率.最后通过数值实例验证了理论推导的正确性和文中方法的有效性.     

考虑负荷类型的配电网改进牛顿潮流算法

针对传统牛顿法存在计算量大、效率低,且当负荷类型不再是恒功率时其迭代次数与时间会明显增加等问题,提出了一种改进的牛顿潮流法。该算法考虑了负荷类型,将恒功率、恒电流和恒阻抗结合起来组成ZIP负荷模型,采用矩阵分裂以及矩阵求逆运算的松弛方法,使求解过程简单、快捷,有效地提高了算法效率,削弱了负荷类型变化对迭代次数以及迭代时间的影响。采用33节点系统测试比较了算法的迭代次数和迭代时间,证实了算法的有效性;并通过潮流计算结果分析了负荷类型对系统电压的影响,结果表明,恒阻抗负荷比例的增加有利于提高系统节点电压。     

块三对角线性方程组的一种并行迭代算法

系统工程计算在科学计算中,单台处理机不能满足需要,为提高计算效率和精度,采用并行处理是一个非常好的块三对角线性方程组的办法,提出了分布式环境下求解块三对角线性方程组的一种并行计算,算法是充分利用系数矩阵结构的特殊性,通过对系数矩阵进行适当地分解构造的迭代算法,使得算法需要在相邻处理机之间进行并行通信三次.并从理论上给出了算法收敛的一个充分条件.最后,在HP rx2600集群上进行了数值仿真,结果表明,实算与理论是一致的,提高了并行效率和精度.     

求解鞍点问题的一般加速超松弛方法

针对大型稀疏鞍点问题给出了一种含有待定参数的新迭代解法,将其称之为一般加速松弛方法,简记为GAOR方法．当参数α=时,新迭代方法是变成由Golub等人给出的SOR-Like方法．该迭代法的构成是基于对系数矩阵进行的一种分裂．迭代法需要选择一个预处理矩阵和待定参数,通过适当选取预处理矩阵和待定参数,新迭代法是收敛的,并且以定理的形式给出了新迭代方法的迭代矩阵的特征值和参数之间的基本等式,从而也导出了迭代法收敛的充分和必要条件．理论结果表明新方法更具有广泛性,并且适当的选择参数可以使新方法较SOR-Like方法具有更快的收敛速度．在文中的最后给出了迭代法的数值试验结果．     

一类Toeplitz三对角方程组的一种分布式并行算法

文中提出一类Toeplitz三对角方程组的一种分布式并行算法。该算法以系数矩阵的分解为基础,充分利用了系数矩阵结构的特殊性,算法因并行化而引入的冗余计算量非常少,算法的通信机制简单,通信量仅与处理 机台数p有关,与方程组规模n无关,算法具有很高的并行效率,理论分析和数值试验表明,其加速比Sp(n)→p(n→ ∞）,此为线性加速比的理想情况。文中给出了算法在分布存储多计算机系统上的数值试验结果。     

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.