微粒群融合虚拟力的异构网络覆盖优化策略

研究异构无线传感移动网络的节点覆盖优化问题。为了有效提高异构网络覆盖率,在分析了传统虚拟力算法缺陷的基础上,提出了一种将虚拟力影响因子融入微粒群算法,以解决网络全局优化。首先以网络有效覆盖率为优化适度值,建立网络覆盖数学模型,然后计算六边形布局下的虚拟力距离阈值,将其作为影响参照值作用到微粒群中,防止微粒陷入局部极值,从而指导微粒进化,得到最优网络覆盖;最后通过仿真测试算法性能。仿真结果表明,在由骨干节点与普通节点组成的异构网络中,微粒群融合虚拟力优化算法有更加明显的改善网络覆盖率的优势,且得到经过此算法优化的任何随机部署无缝覆盖的最佳节点数量。     

基于虚拟力的异构无线传感器网络覆盖优化策略

针对异构无线传感器网络覆盖优化过程中,固定Sink节点的虚拟作用力限制移动节点的位置移动,导致覆盖盲区得不到全局修复的问题,本文结合计算几何理论,提出基于Voronoi多边形形心引力的虚拟力覆盖优化算法（CAVFA）。虚拟力算法能有效指导移动节点的散布过程,形心引力能更好地实现全局的覆盖优化。通过合理设置虚拟力的距离阈值参数和优先级,调整固定节点对移动节点的约束。仿真表明,相比传统VFA算法和CBA算法,本文提出的CAVFA算法能够更有效地提高异构网络的覆盖率,且算法收敛速度更快。     

一种结合粒子群和虚拟力的动态节点部署策略

无线传感器节点部署是无线传感器网络研究的关键问题,面对工作在复杂环境下的众多传感器节点,模拟了一个由随机部署的固定节点和移动节点构成的无线传感器网络环境。为了优化节点的布局,将粒子群算法与虚拟力相结合,提出了一种虚拟力扰动指数权值递减型粒子群算法,该策略通过改进粒子群算法加快了粒子进入局部搜索的速度,并异构了节点间虚拟力来影响粒子群算法中粒子的进化过程,提高算法收敛速度。仿真结果表明,和传统的粒子群算法相比,提出的算法可以得到更高的覆盖率,且收敛速度更快。     

基于定向移动的水下传感器网络覆盖算法

覆盖率是衡量无线传感器网络服务质量的重要指标。为提高网络覆盖率,针对水下三维传感器网络模型,提出一种基于定向移动的虚拟力算法。将虚拟力简化为节点只受邻居节点的斥力作用,定义当2个邻居节点的感知圆球相切时,其位置为相对理想位置。节点所受虚拟力大小与节点移动到相对该邻居的理想位置所需移动的距离成正比,而节点移动的距离与节点所受到的虚拟力的合力相关。实验结果表明,该算法能有效地对水下传感器网络的布局进行优化,提高网络覆盖率。     

基于安全连接的 WSN 节点优化部署

针对目前无线传感器网络节点覆盖优化方案中,无线传感器网络节点位置移动会破坏节点间的共享密钥的问题,采用了一种基于泰森多边形形心引力和存在共享密钥节点间的安全连接虚拟力的无线传感器网络部署方案.该方案以提高节点覆盖率为优化目标,引入安全连接虚拟力,以保证节点的安全连接;采用改进泰森多边形形心引力的虚拟力方案,能够有效指导节点散布过程和实现全局优化.通过仿真实验表明,本文方案能够提高节点的覆盖率,并且能够的减小存在共享密钥的安全连接的破坏.     

基于自适应差分优化的改进虚拟力导向粒子群算法研究

为提高节点在无线传感器网络中的自部署性能,本文以虚拟力导向粒子群算法为基石,在部署区域内,采用正方形网格划分方式,并引入一种改进的自适应差分进化策略,对原算法进行改进。改进算法引入了移动目的地对移动节点的引力作用,并通过自适应调整,有目的的向扩大网络覆盖率的目标进化,从而最大限度地优化节点的部署速度和网络的覆盖率。通过对该算法的性能进行了仿真与分析,在网络覆盖率、算法收敛速度以及部署时间等方面,相比于经典虚拟力算法及虚拟力导向粒子群算法,该算法具有更佳的部署性能。     

基于自适应粒子群的WSN覆盖优化

数据感知层的无线传感器网络覆盖范围对感知服务质量具有非常重要的意义。鉴于无线传感器网络初始部署的随机性所造成的覆盖冗余、覆盖空洞以及粒子群算法自身的早熟收敛等问题,提出一种基于二项感知覆盖的自适应虚拟力粒子群优化算法,以优化网络的有效覆盖率。该算法通过在网络中添加移动节点来进行位置调度的重部署分布,并计算种群进化程度和相对聚合程度以自适应调节惯性权重,同时利用适应度方差阈值判断当前状态是否需要引入虚拟力策略的干扰。文中重点分析了初始部署类别和移动节点占比对重部署覆盖性能的影响,并给出了相应的算法实现。仿真实验表明,相比ACPSO,DACPSO,DVPSO算法,改进的粒子群算法的覆盖率达到了98.33%,并且具有较高的移动效率,充分证明了该算法的有效性。     

基于虚拟力和多种群粒子群的覆盖优化HSN节点部署并行算法

针对异构传感器网络中由于节点随机部署而导致覆盖盲区和覆盖冗余的问题,以最大化网络的覆盖率为目标,设计了一种基于虚拟力和多种群粒子群的异构移动节点部署并行算法;首先建立了改进的异构节点概率感知模型和目标优化函数,然后采用虚拟力算法在虚拟力的作用下引导节点移动进行初始部署,为了进一步提高网络的覆盖率和部署的效率,采用改进的多种群粒子群并行算法实现对节点部署的寻优,并定义了具体的部署算法,为了增强网络的鲁棒性,设计了一种当节点失效时的自适应节点替换机制;仿真实验表明:文中方法得到的平均网络覆盖率为95.6%,与其它方法相比,具有较高的网络覆盖率和较少的部署时间,具有较大的优越性。     

随机异构传感器网络中基于虚拟节点的调度算法

针对随机异构传感器网络节点调度过程中覆盖率和能耗的平衡问题,论文面向具有随机异构属性的无线传感器网络,提出了一种基于虚拟节点的调度算法(SAVSH)。通过部署虚拟节点,与原网络拓扑共同构建Delaunary三角剖分,分配节点受力来源。利用三角形平衡点实现网络整体的覆盖优化;通过三角形关键点完成节点位置的精确定位;引入二进制编码,完成对越界关键点的识别,及其对边界节点的约束受力设计。仿真结果表明,SAVSH在稳定的短移动距离下,能够高效地提高异构网络的覆盖率,且与同类算法相比,SAVSH在收敛速度上表现出一定优势。     

WSN中基于虚拟力的移动覆盖算法

以往移动覆盖算法的主流思想通常为：根据特定算法移动部署好传感节点后,转为静态无线传感器网络进行工作,即网络只在节点部署阶段处于移动状态。针对稀疏无线传感器网络按此思想覆盖率极低,并且通常网络也只需对目标区域实现动态覆盖的问题,提出了基于虚拟力的移动覆盖算法。算法采用虚拟力思想部署节点,划分出节点工作区,并依据等周定理规划出移动轨道,以最小化节点移动距离,并减少重叠覆盖面积,降低感知能耗。仿真实验结果表明,该算法实现了对目标区域的高覆盖率,并有效提高了网络的能量利用率,具有较强实用性。     

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.