一种能量高效的非均匀分簇算法

针对无线传感器网络中的能量消耗不均衡问题,提出一种能量高效的非均匀分簇算法--EUCA。算法采取基于节点剩余能量的簇首选举策略,簇首采用非均匀分簇的思想来构建大小不等的簇,在构建簇间路由树时,综合考虑了邻近簇首的剩余能量、簇成员数目、相对自身的距离和相对基站的距离,以此来均衡簇首能量损耗。仿真结果表明,该算法有效均衡了网络能量损耗,延长了网络的生存周期。     

基于区域分簇的大规模无线传感器网络生命周期优化策略

针对环境监测、电网冰灾监测等大规模监测系统中监测区域覆盖广、传感器数量大等特性,为节约网络能耗以延长生命周期,提出了一种基于区域分簇的大规模无线传感器网络生命周期优化策略(RCS).该策略首先利用传感器节点的位置信息进行凝聚的层次聚类(AGNES)算法将大规模网络分区以优化簇首的分布;其次,候选簇首节点竞选簇首成功后进行不均匀分簇,同时加入时间阈值来均衡簇首节点的能耗;最后,采用簇间多跳路由,根据节点剩余能量、与汇聚点距离计算网络能耗代价来构建最小生成树进行路由选择.在仿真实验中,该策略与经典的低功耗自适应分簇(LEACH)协议和能量高效的非均匀分簇(EEUC)算法比较,簇首能耗平均分别减少了45.1%和2.4%,网络生命周期分别延长了38%和3.7%.实验结果表明,RCS在大规模网络中能有效均衡整体网络能耗,显著延长了网络的生命周期.     

一种基于分环的能量高效无线传感器网络分簇路由协议

针对现存分簇路由协议能耗不均衡和簇首节点死亡过早的缺陷,设计了一种基于分环模型的能量高效分簇路由协议.根据节点剩余能量和位置选举簇首,采用主次簇首轮换方式减低簇首节点能耗.仿真结果表明:该算法能够均衡网络能耗,延长无线传感器网络生命周期.     

基于投票策略的异构传感器网络分簇算法

为了减少传感网络节点的能量消耗,提出了一种基于节点投票策略的异构传感网络分簇算法.通过坐标位置分割地理区域,根据剩余能量和距离,对每个区域内节点投票选举产生簇首,从而使能量消耗最慢和高剩余能量的节点优先当选为簇首.为了保证簇首能量消耗均衡,簇首之间基于剩余能量和距离形成多跳路由,簇首收集数据融合后转发到基站.仿真结果表明,在异构网络下,VSCA与早期的几种分簇路由算法相比,提高了网络的稳定周期,延长了网络生存时间,获得了更高的数据吞吐量.     

一种适用于煤矿井下无线传感网的能量均衡路由协议

矿井无线传感网的拓扑呈长距离带状,节点间能耗不均问题十分严重。非均匀分簇策略能从全局均衡节点能量负载,在矿井中具有良好的适用性。针对矿井传感网的带状特性提出了一个簇规模自适应调节的能量均衡分簇路由协议。协议根据节点离汇聚点的距离、剩余能量及分布密度来构造规模不等的簇。簇首的竞选以节点相对于周围候选者的能量水平为依据,避免了低能量节点被当选为簇首。簇间多跳路由算法依簇首近似线型的分布特点设计,不但考虑链路能耗最优,亦注重转发节点间的能量均衡。模拟实验结果表明,该路由协议显著平衡了网中节点能耗,延长了网络生存时间。     

基于最小生成树的非均匀分簇路由协议

针对无线传感器网络中利用分簇技术,簇首到Sink节点通信采用多跳路由方式容易引起"能量空洞"的问题,提出了基于最小生成树的非均匀分簇路由协议.该协议在簇首选举阶段,以节点剩余能量、节点度、节点能量消耗速度为权重计算簇首竞争等待时间,选用簇首竞争等待时间小的节点为簇首,以均衡能量;簇形成后,以剩余能量、簇间的距离和能量消耗为参数构建基于最小生成树的最优传输路径通过多跳方式将数据发送到Sink节点.仿真结果表明,该路由协议能有效均衡能耗,延长网络生命周期,延缓"能量空洞"的形成.     

一种基于时间延迟机制的WSNs非均匀分簇算法

为减少无线传感器网络分簇路由协议中节点竞争簇首时多余的能耗,解决簇首能耗不均的问题,提出一种基于时间延迟机制的非均匀分簇算法。该算法使能量较多的节点被优先选为簇首,并提出了簇首竞争半径的计算方法,确保其数目稳定且位置均匀分布。成簇过程中,节点根据最小消费函数选择簇首,簇内成员加入时考虑簇首能量、二者距离以及簇首和汇聚节点角度等因素来均衡簇首能耗。仿真结果表明:算法能有效地均衡节点能耗,延长网络寿命,分别比CHTD和EEUC算法延长了35.1%和12.9%。     

基于学习自动机的无线传感网能量均衡分簇算法

优化簇首选择、均衡节点能量负载以延长网络存活时间,一直是无线传感器网络分簇协议研究的重点。针对无线传感器网络节点随机分布的情况,在基于学习自动机(Learning Automata, LA)的ICLA算法基础上,提出一种兼顾节点密度的能耗均衡分簇算法。在簇头选举方面,综合考虑节点剩余能量和节点密度,利用学习自动机与周围环境进行信息交互和动作奖惩,选择出相对较优的簇头;根据簇首与基站距离和其节点密度构造大小非均匀的簇,实现不同位置不同网络疏密程度下簇内和簇间能耗互补均衡;构造了基于簇首剩余能量、簇内节点密度和传输距离的评价函数,并运用贪婪算法选择出最优中转簇首进行多跳传输。仿真实验结果表明,该算法能选择出更为合理的簇头,有效地均衡网络能量负载,延长网络生存时间。     

优化分簇的无线传感器网络路由算法

延长传感器网络的生存周期,降低网络节点的能耗成为无线传感器网络(WSN)研究的关键.由于无线传感器网络能量有限,针对LEACH算法中簇首分布不均、簇首数目偏离最优值等对网络能耗的影响,提出了一种同时考虑节点剩余能量、最优簇数和簇首分布状况来选择簇首的算法EBCS-LEACH.新算法使簇首数目为最佳,以满足能量阈值的节点才能当选为簇首和对簇首的分布进行了相应调整.仿真结果表明,EBCS-LEACH算法延长了网络的生存周期,相比LEACH算法生命周期延长19.5％,同时能耗也更加均衡.     

一种综合能量和节点度的传感器网络分簇算法

针对无线传感器网络分簇过程中簇首耗能过快问题,提出了一种综合节点剩余能量和节点度数进行簇首选取的分簇算法ENCA(energy and node degree synthesized clustering algorithm).该算法在每轮的簇首选取中考虑了每个簇内所有节点的剩余能量和平均剩余能量,并在每个簇中依据节点的度数优化簇首的选择.在算法运行过程中,在保证网络连通的同时,避免了能量较低的节点当选为簇首.仿真结果表明,与LEACH算法和ACE算法相比,ENCA算法均衡了网络中节点的能量消耗,有效延长了网络寿命.     

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.