一种改进的无线传感器网络LEACH协议及仿真

针对无线传感器网络经典LEACH协议中簇首数目选择及通信方面的不足,提出一种改进的M-LEACH算法,对如何动态确定最优簇数目进行了研究,分析了影响最优簇数目的因素,推导出了最优簇首比例公式,同时给出了一种能量均衡的无线传感器网络分簇路由算法。仿真实验结果表明,与经典LEACH协议相比,运行M-LEACH协议后能够减少网络能耗和均衡网络能耗,延长网络的生命周期。     

一种能量均衡的无线传感器网络分簇路由协议

由于无线传感器网络节点能量有限,为均衡无线传感器网络节点之间的能量消耗,提高整体网络的生命周期,针对LEACH协议中簇首选举时未考虑节点剩余能量因素、随机分簇等不足,提出了一种改进的LEACH协议.改进的LEACH协议在簇首选举时,以节点的剩余能量作为重要参考依据,优化节点担任簇首的概率.仿真结果表明,与传统的LEACH协议相比,改进的LEACH协议达到了能量消耗均衡的目标,从而延长了网络的生存寿命.     

一种基于LEACH的改进无线传感器网络路由协议

为了在无线传感器网络(WSN)中降低能耗和提高网络生存期,针对LEACH协议中簇头选举不合理和随机分簇的不足,提出了一种LEACH的改进协议.该协议首先计算无线传感器网络的最佳分簇数量,然后与遗传算法相结合对网络进行分簇,再根据簇中节点的剩余能量等情况选出簇头节点.仿真结果表明,与经典的LEACH协议相比,改进后的协议减少了网络的能量消耗,延长了网络生命周期.     

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.     

基于LEACH的WSNs分簇优化策略

针对LEACH算法中能量消耗不均匀的缺陷,本文提出了一种改进的路由协议来提高无线传感器网络的能量效率。在簇首选择阶段,引入节点剩余能量和初始能量来调节传感器节点随机数的大小;在成簇阶段,该算法将节点的剩余能量和距离汇聚节点的远近作为成簇的依据,使簇首的分布更加合理;在数据传输阶段,将节点与汇聚节点之间的距离及节点的剩余能量相结合,提出一种单跳与多跳相结合的传输方式,从而减少了能量消耗。仿真实验表明,改进后的算法能够更好的减少能耗,延长无线传感器网络的生命周期。     

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。     

基于无线传感器网络LEACH协议的改进算法

基于无线传感器节点的位置信息及剩余能量,提出了一种基于LEACH协议的改进算法-PE-LEACH协议。PE—LEACH协议基于节点的位置信息进行分簇,基于节点的剩余能量及位置信息进行簇头的选择,当簇头距离汇聚节点较远时采取中转方式传送数据。较好的平衡了网络能量负载,延长了网络的生命周期。仿真结果表明：PE—LEACH协议与LEACH协议相比,提高了网络能量的利用率,延长了节点的生命周期。     

一种新的基于LEACH的WSN路由算法

研究无线传感器网络路由算法,无线传感器网络由能量有限的节点组成,因此高效节能的路由算法是无线传感器网络组网的基础.针对低功耗自适应分簇(LEACH)路由算法存在簇首节点选择不合理以及簇首节点与基站在远距离通信过程中能量消耗大的不足,提出了一种改进的LEACH路由算法.改进的算法在簇建立阶段的簇首选举过程中,引入节点剩余能量因素,且进行均匀分簇,有效地降低剩余能量较小和位置不佳节点成为簇首的可能性,均衡了网络的能量消耗,在簇稳定工作阶段,节点间的数据传输采用单跳和多跳相结合的通信方式,从而降低网络能耗.仿真结果表明,与传统的LEACH算法相比,改进的LEACH算法能量均衡性更好,并显著地延长了网络的存活时间.     

LEACH-REC算法的研究及实现

LEACH(低功耗自适应集簇分层协议)是无线传感器网络中常用的分簇路由算法。在LEACH算法的基础上,提出一种基于节点剩余能量和区域中心化的算法(LEACH-REC)。该算法从两个方面进行改进,在回合的建立阶段,根据节点的剩余能量和位置选择簇首;在数据传输阶段,将簇首分成不同的区域,某个区域的簇首节点根据weight(i,j)的值选择下一跳,直到数据传输到sink节点。模拟实验表明,对比LEACH和LEACH-ED,该算法(LEACH-REC)传感器网络的生命周期分别延长了600和400回合左右,网络的服务质量有明显的提高。     

一种分布式能量有效的无线传感器网络分簇路由协议

提出了一种分布式能量有效的无线传感器网络分簇路由协议DEEC(Distributed Energy-efficient Clustering Algorithm)。该协议采用基于时间的簇首选择算法,广播时间取决于自身剩余能量和其邻居节点的剩余能量。在数据传输阶段,采用簇内单跳与簇间多跳相结合的方式,引入权值函数优化簇首中继节点的选择。仿真实验结果表明,与LEACH,PEGASIS协议相比,DEEC能够有效地节约单个节点能量、均衡网络能耗、延长网络生存周期。     

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.