无线传感器网络最小连通覆盖集问题求解算法

降低能耗以延长网络生存时间是无线传感器网络设计中的一个重要挑战.在传感器节点高密度部署的环境中,在保证网络性能的前提下,仅将最少量的节点投入活跃工作状态,而将其余节点投入低功耗的睡眠状态,是一种节约系统能量的有效方法.如何计算同时满足"覆盖要求"(工作节点必须能够完全覆盖目标区域)和"连通性要求"(工作节点组成的通信网络必须是连通的)的最小节点集合,是一个NP难问题.设计了一种基于目标区域Voronoi划分的集中式近似算法(centralized Voronoi tessellation,简称CVT),用于计算完全覆盖目标区域所需要的近似最小节点集.当节点通信半径大于等于2倍感知半径时,CVT算法构造的节点集是连通的;当节点通信半径小于2倍感知半径时,设计了一种基于最小生成树(minimum spanning tree,简称MST)的连通算法来计算确保CVT算法构造的覆盖集连通所需的辅助节点.理论分析和实验数据表明,CVT(+MST)算法的性能在时间复杂性和连通覆盖集大小方面都优于已有的贪婪算法.     

感知距离参数优化的无线传感器网络节能的研究

无线传感器网络(WSNs)覆盖是WSNs的关键问题,它反映了网络对目标区域的探测能力,节点的感知距离的优化能够很好地解决WSNs区域覆盖要求的同时使得能量消耗最低.研究了基于节点感知距离参数调节的WSNs节能区域覆盖方案,建立了感知半径之和最小的数学模型,采用遗传算法求解该模型,得到一个最优解.仿真结果表明:与传统覆盖方案比较,所提方案在满足覆盖要求的同时有效地降低了网络能量消耗.     

半径可调的无线传感器网络三维覆盖算法

针对三维无线传感器网络区域中节点覆盖的问题,提出一种半径可调的无线传感器网络三维覆盖算法（3D-CAAR）。该算法利用虚拟力作用实现无线传感器网络的节点均匀部署,同时结合传感器节点的半径可调覆盖机制,判断节点与被覆盖区域中目标点之间的距离。引入能耗阈值,使得节点根据自身情况调节节点感知半径,从而降低无线传感器网络的整体能耗,提高了节点利用率。最后,通过与传统基于人工势场的三维部署算法（APFA3D）、基于与未知目标精确覆盖的三维算法（ECA3D）仿真实验对比,3D-CAAR的事件集覆盖效能明显较高,能有效解决三维无线传感器网络中对目标节点的覆盖问题。     

无线传感器网络中基于Voronoi覆盖及Delaunay三角剖分图的最小刚性拓扑控制算法

为同时满足覆盖与节能应用需求,本文提出了无线传感器网络中一种最小刚性拓扑控制算法MRTc（Minimal rigid topology control algorithm based on Voronoi coverage and Delaunay triangulation）.该算法基于Voronoi覆盖机制,准确控制节点工作状态,实现活动节点对目标区域的完全覆盖.在此基础上,MRTc利用Delaunay三角剖分图的特点,构建出适用于无线传感器网络的最小刚性拓扑结构.该结构有效约束了网络平均节点度,且同时具有容错性、覆盖性和稀疏性.此外,MRTc引入节点功率控制策略,在维持网络完全覆盖的基础上最小化节点能耗.仿真结果进一步验证了本文提出的MRTc算法的有效性.     

无线传感器网络一维区域的覆盖研究*

无线传感器网络覆盖问题的研究应综合考虑感知覆盖、通信覆盖和连通覆盖三个方面,建立适合不同监测空间的节点覆盖模型。讨论了无线传感器网络一维区域的覆盖问题,对无线传感器网络中一维直线区域出现的问题进行分析,讨论了均匀分布情况下的节点覆盖概率和覆盖数的计算方法,仿真实验表明节点感知半径是影响节点覆盖率和覆盖数的主要因素。     

基于贪婪策略的无线传感器网络覆盖优化方法

对目标监视区域实现有效的覆盖是无线传感器网络（ WSNs）最基本也是最重要的问题之一。当WSNs不能满足覆盖要求的时候,需要通过节点调度算法,新激活一批节点来恢复网络的覆盖性能。本算法摒弃了计算感知模型重叠情况,利用网络的几何特征进行覆盖质量评价与优化。仿真结果表明：所提出的算法确实能迅速提高覆盖率的同时降低节点的激活数量。     

多感知范围无线传感器网络中一种分布式目标覆盖算法

基于多感知范围无线传感器网络中节点与目标的覆盖关系,设计了一种目标生命期评估机制。鉴于网络生命期由具有最小生命期的目标决定,在分析节点感知半径变更影响的基础上,提出了两种提高最小目标生命期的策略,建立了一个动态目标覆盖博弈模型,并证明了该博弈存在纯策略的纳什均衡。本文设计了一种分布式目标覆盖算法,算法中节点根据邻居节点的能量分布和目标覆盖情况,选用最优感知半径,以确保目标完全覆盖并延长最小目标生命期。仿真结果表明,在不同的网络中所提算法均能有效地延长网络生命期。     

任意感知模型的传感器网络覆盖度判定算法

覆盖问题是无线传感器中的一个基本问题,反映了网络所提供的"感知"服务质量,为解决任意感知模型的无线传感器网络覆盖度判定问题,结合区域封闭性和计算几何的相关知识,本文提出了将复杂的区域覆盖问题转化为易于解决的点覆盖问题。在此基础上,给出了基于覆盖交点集合的判断算法,即找到任意两个传感器感知区域边界线之间以及每个传感器与覆盖区域边界线之间的所有交点,其中位于覆盖区域内或者边界上交点的最小覆盖度即为传感器网络的覆盖度。     

基于微粒群优化的有向传感器网络覆盖增强算法

覆盖作为无线传感器网络监测中的基础问题反映了无线传感器网络的感知服务质量.在分析节点主感知方向可调模型的基础上,提出了一种微粒群优化的有向传感器网络覆盖增强算法.该算法针对节点主感知方向设计微粒适应值函数和种群进化策略, 以区域覆盖率为优化目标,通过微粒群优化有效调整传感器节点的主感知方向,从而达到有向传感器网络的覆盖增强.实验验证了算法的有效性.     

基于虚拟力算法的WMSNs覆盖研究

为了提高无线多媒体传感器网络（WMSNs）区域覆盖率,在传感器节点随机部署后,通过调节传感器节点的感知方向,使节点从感知重叠区域向覆盖盲区转动,提高网络覆盖率。针对现有算法中存在覆盖效率和覆盖率不能统一的问题,提出一种改进的虚拟力覆盖算法（VFARCR）,该算法利用传感器节点感知扇形区域质心点间的斥力调节感知方向,且通过传感器节点间的覆盖冗余度的决定方向调整的大小,虚拟力和覆盖冗余度共同控制传感器的转动。仿真实验表明：该算法提高了覆盖效率和覆盖效果,提高了虚拟力覆盖算法的性能。     

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     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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。