一种基于链暗示技术的Min-CVCB问题的精确算法

随着VLSI(超大规模集成电路)技术的发展,关于可重构阵列二分图的受约束最小点覆盖(Min-CVCB)问题受到了很多文献的关注.作为点覆盖问题的子问题,该问题已被证明是NP-完全问题.人们利用核心化和分支即使给出了时间复杂度为O((ku k1)|G| 1.26ku k1)的目前最好算法,然而仍不能满足实际工程的需要.通过进一步深入分析二分图的结构,对含有权值大于或等于3的块的连通子图分析其可能连接情况后充分利用"链暗示"技术和分枝搜索技术来建立起新的搜索递推关系;对于分枝后的块提出了一种动态规划算法,其可在多项式时间内完成处理.整个参数算法的运行时间为O((ku k1)|G| 1.1892ku k1),极大地改进了目前的最好结果.     

无线网络中最小权虚拟骨干网连通部分的新方法

无线网络中的虚拟骨干(VB)是一些无线节点的子集,因此只有VB中的节点负责路由相关任务,并且VB总权值越小会导致开销越少。在一个点赋权的无线网络中,不单要考虑VB中节点数的多少,更重要的是要考虑其总权值的大小。通常,一个赋权无线网络被模型化为一个点赋权单位圆盘图(UDG),相应地赋权无线网络中的最小权VB问题被抽象为点赋权UDG中的最小权连通控制集(MWCDS)问题进行研究。求MWCDS是一个NP-难问题。为降低点赋权UDG中MWCDS问题的近似比,在连通部分提出一种新方法——基于度的点赋权Steiner树算法。结合目前最好的结果,对于UDG中的MWCDS问题将得到一个(3.32+ε)-近似算法。同样地,对于UDG中的最小权顶点覆盖(MWCVC)问题也将得到一个(3.32+ε)-近似算法。证明了通过改进连通部分的近似比令点赋权UDG中MWCDS问题的近似比降低的方法是可行的。     

内部节点受限的最小生成树问题算法研究

研究内部节点受限的最小生成树问题：给定一个赋权无向完全图[G=V,E],假定[w:E→R+]为边集[E]的权重函数且满足三角不等式,给定点集[V]的一个子集[RR?V],目标是寻找图[G]的一个满足[R]中的点皆为内部顶点的权重最小的生成树。由于该问题是[NP-]困难的,提出了一个伪多项式时间最优算法,设计了一个近似比为2的多项式时间近似算法,并且给出例子以说明该近似比是紧的。     

高维空间球集覆盖问题的改进1+ε近似算法

高维空间球集的覆盖问题是指对高维空间中多个球构成的集合S,构造一个直径最小的球来覆盖S中所有已知球。本文提出了球集直径的概念,给出求解球集直径的1/3~(1/2)近似算法。基于此算法求解球集实例集合S的初始核心集,进而给出高维空间球集覆盖问题的1+ε近似算法,算法时间复杂度为O(nd/ε+d2/ε3/2(1/ε+d)lg1/ε)。算法保证核心集中球的个数为O(1/ε),与S中球的个数和空间维数无关。     

基于积极集策略的最小闭包球问题算法研究

首先,基于每次迭代计算距离当前球心最远的两个点,提出一种求解n维空间中m个点的最小闭包球问题的(1+ε)-近似算法.对于ε∈(0,1),建立了该算法的核心集大小和计算复杂度,分别为O(1/ε)和O(mn/ε).然后,给出一种积极集策略,每次迭代计算距离当前球心最远的N个点.将该策略结合到提出的算法中,得到一个基于积极集策略的算法.最后,实验结果表明基于积极集策略的算法能够快速、有效地求解m》n的大规模数据集的近似最小闭包球.     

一般图中的最小概要表示集问题

在一般图中,通常基于图的拓扑结构来刻画任意2个节点之间的相似度。基于节点相似度提出概要表示集SRS的概念,从图中寻找最少节点数的概要表示集称为最小概要表示集问题。证明了在一般图中求解最小概要表示集问题是NP (非确定性多项式)难的,不太可能存在多项式时间复杂度的精确算法。基于次模函数提出了多项式时间复杂度的贪心近似算法,用于求解最小概要表示集问题,得出近似比结果。     

带测度函数的连通支配集问题

连通支配集问题在网络广播上有着广泛的应用,本文引入测度函数的概念,提出了带测度函数的连通支配集问题（CDS（F））,使得它具有更广的应用范围。文中首先给出问题的形式定义,证明了它在各种情形下的NP完全性,并给出多项式时间的近似算法,它的近似度为Ln△＋3（△为图中顶点的最大度数）。     

一种可重构阵列的最小瑕点覆盖算法

关于可重构阵列的瑕点覆盖问题受到了很多文献的关注，特别地，关于可重构阵列的最小瑕点覆盖问题等价于二分图的受约束最小点覆盖问题，并被证明是NP-完全问题。针对本问题提出的算法运行时间为O(1．19^k kn)，这里k为可替换行与列的数目，改进了原有的最好结果，其运行时间为0(1．266k kn)，较好地组合并扩展了研究参数计算的最新技术与经典匹配理论，且具有较好的实用价值。这是关于可重构阵列的最小瑕点覆盖问题算法又一较大的改进，也是目前最小点覆盖问题相关参数算法的较有意义的改进。     

集合多覆盖问题的乘性权重更新分析

集合多覆盖问题的简单贪心算法的近似比是lnn＋1。本文提出简单贪心算法的一个变形,宽度优先贪心算法,并且证明其有近似比（lnn）／r＋lnlnn＋O（1）,其中r是覆盖要求。这个结果比由随机取整方法得到的近似比O（（lnn）/r＋√（lnn）＋1为优。宽度优先贪心算法的设计可以归入Arora等最近提出的乘性权重更新方法的框架。关键词集合多覆盖,宽度优先贪心算法,乘性权重更新方法     

控制集与部分控制集问题的原始-对偶算法

图的控制集问题是一类应用广泛的组合最优化问题。本文利用控制集和部分控制集问题的整数规划模型和原始-对偶方法,分别给出这两个问题近似度为△＋1的近似算法（△为图中顶点最大度）。     

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.