一种改进的LEACH模型及其仿真分析

为了最大限度地延长无线传感器网络生命周期,对无线传感器网络传统路由算法低功耗自适应聚类LEACH进行改进,改进后的算法命名为LEACH-EC.在广播阶段选取簇头节点时引入高概率选取机制,根据节点的剩余能量和节点的集中度选取簇头节点,选取的簇头节点兼顾了节点剩余能量和节点分布状况.实验结果表明,LEACH-EC算法选取的簇头节点性能较优,能有效地减少簇内节点传输能量消耗.因此,LEACH-EC算法能够均衡无线传感器网络能耗负载,延长无线传感器网络生命周期     

基于LEACH的无线传感器网络混合优化协议算法

在无线传感器网络(WSN)协议研究中,降低节点的能量损耗、延长节点的使用寿命是研究的关键问题。针对无线传感器网络中传统LEACH协议在分簇机制及数据通信方面的不足,提出了一种混合优化的改进协议--HOBDE-LEACH。新的协议采用先分簇再选举簇头的策略,提出覆盖半径种子扫描成簇算法(CR-SSCA)进行快速分簇,保证对区域的全覆盖;网络运行期间结合能量和距离考虑负载均衡,分阶段采用不同的簇头选举和通信机制。仿真实验结果表明,与LEACH协议相比,HOBDE-LEACH的第一个节点死亡的轮循次数延长了66%,50%节点死亡时的网络轮循次数延长了20%;与LEACH-EI协议相比,所提协议的第一节点死亡的轮循次数延长了50%,50%节点死亡的网络轮循次数延长了19%。改进后的协议能有效地均衡网络负载和簇头节点能量消耗,更合理地分布簇头节点,延长网络生命周期。     

依托路由规则的自适应能量优化分簇无线传感器网络路由算法

针对分簇无线传感器网络中节点能量负载不均衡导致簇头在任务较多的情况下过早死亡,以及路由能量损耗较大等问题,提出一种自适应能量优化分簇的路由算法。在簇头选举和竞争半径的计算上通过权衡系数充分考虑了竞选节点的剩余能量与距离情况,延长了簇头的生命周期。以路由规则的形式来制定簇头间转发数据是采用单跳路由还是多跳路由,在保证簇头不会过早死亡的情况下最大化减少路由的能量损耗。实验仿真结果表明,自适应能量优化分簇的路由算法可以延长网络节点的生命周期,减少能量损耗。     

基于节点密度的无线传感器网络成簇算法

降低传感器节点的能量损耗,延长网络生命周期,一直是无线传感器网络路由协议研究的重点。根据LEACH算法的特点以及网络节点可能出现簇头分布不均匀的状况,提出一种基于节点相对密度选取簇头的成簇算法LEACH-D。在该算法中簇头的选择考虑了节点分布密度,同时在数据传输中采用建立簇树路由的机制来完成多跳通信。并且通过MATLAB的仿真证明了改进算法在能量损耗和延长生命周期方面比原有算法有了比较大的提高。     

一种基于聚合度模型的WSNs双簇头分簇路由协议

在无线传感器网络（WSNs）中能量负载不均衡问题,影响了网络的生命周期。提出一种基于聚合度模型的WSNs双簇头分簇路由协议（DCHP）,DCHP协议将节点聚合度与剩余能量作为考虑因素引入阈值计算,从而使高剩余能量且聚合度高的节点优先选为第一簇头。在此基础上,根据簇内节点能量选出第二簇头,完成簇间多跳路由转发数据。仿真实验表明：DCHP协议能更好平衡网络能量负载问题,延长网络生命周期。     

无线传感器网络节点可靠性分析

本文通过对现阶段无线传感器网络可靠性因素进行分析,对原有LEACH协议进行改进,提出了种新的节能、拓扑可靠的簇算法ERCTNA（Energy—effcient and reliable cluster algorithm for topology）。ERCTNA算法通过簇头辅助节点的设置和优化信息传输模式可以平衡簇头的能量负载,增加网络的拓扑可靠性。这种模式改善了传统无线传感器网络中长距离通信带来的能量过度耗损问题,有效的延长了整个网络的生命周期,提高了无线传感器网络的可靠性。     

多媒体传感器网络中基于两跳簇结构的图像传输方案

与传统无线传感器网络节点能量绝大部分消耗在无线收发上不同,无线多媒体传感器网络中数据处理与传输能耗具有“均匀“分布的特点.通过分析表明,传统无线传感器网络簇结构下的数据传输策略并不适合于无线多媒体传感器网络.因此提出了一种基于两跳簇结构的图像传输方案,通过增加中继节点负责图像的压缩编码和转发,在减小相机节点图像传输能耗的同时,大大缓解了相机节点和簇头的图像处理能耗压力.仿真结果表明,该图像传输方案极大的延长了网络的生命周期,非常适合于能量有限的无线多媒体传感器网络.     

一种通过剩余能量过滤进行簇头选举的低能耗无线路由算法

基于LEACH协议提出一种改进的无线传感器网络的自组织路由算法。该算法在原LEACH协议的簇头产生环节做了较大改进,在簇头产生过程中,将当前节点剩余能量与全无线传感器网络节点平均剩余能量进行比较,防止剩余能量小于全网平均剩余能量的节点当选簇头,进一步优化了全网络节点能量消耗的均衡性,有效推迟了节点的死亡时间。通过在簇头选举阶段使用有目的性的筛选取代LEACH的随机选取,实现降低无线传感器网络能耗、延长网络生命周期的目的。通过MATLAB仿真软件进行试验测试,结果表明,改进的算法可以提高无线网络的生命周期,均衡无线网络能量消耗,增加网络吞吐量,有效延迟无线网络节点的死亡时间。     

簇首选择改进的LEACH无线传感器路由协议

针对LEACH(Low Energy Adaptive Clustering Hierarchy)协议能耗大、网络生命周期短等不足,提出一种簇首选择改进的LEACH无线传感器路由协议(M-LEACH)。首先在综合考虑节点剩余能量、网络平均剩余能量、上一轮节点消耗的能量基础上,引入加权因子选择簇首。然后根据接收信息、簇首以及传输ADV的能耗确定簇首的数量,使簇首在网络中分布均匀。最后采用仿真实验进行性能测试。结果表明,相对于LEACH协议以及其他改进的LEACH协议,M-LEACH降低了传感器网络的能耗,使整个网络能量更加均衡,延长了无线传感器网络的生命周期。     

基于优化簇半径的WSNs非均匀分簇路由

为了有效解决无线传感器网络分簇路由协议中,靠近SINK节点的簇头因特发大量数据而过早耗尽能量,提出了一种优化簇半径的非均匀分簇路由协议(UCOR),其核心思想是通过优化簇半径对无线传感器网络进行合理分簇,使靠近SINK节点的簇规模小于远离SINK节点的簇.仿真实验结果表明,与EEUC和LEACH等路由协议相比UCOR路由协议有效地均衡了节点能量消耗,显著地延长了网络生命周期.     

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.