一种基于簇头选择模型的无线传感器网络分簇算法

针对分层结构的无线传感器网络,本文提出了一种分簇算法.节点通过簇头选择模型来决定自己是否被选为簇头.簇头选择模型由节点度(ND)和剩余能量(RE)共同决定.从而提高了网络体系结构的稳定性,减少计算和通信开销.所述分簇算法不仅优化了簇头选择,还均衡整个网络节点的能量消耗,进而延长网络的生命周期.最后通过理论分析和仿真进一步验证该分簇算法的性能.     

基于簇头质量的移动无线传感器网络分簇算法

在部分节点移动的网络环境下,分析了传统静态无线传感器网络分簇算法对节点移动环境下成簇的失效性,给出了影响簇头质量的性能参数集,并提出了基于簇头质量的移动无线传感器网络分簇算法。该算法根据节点活动性、平均邻居距离、节点度偏差及信道质量等簇头性能的影响因子,通过加权的方法计算出簇头质量,在分布式传感网区域内簇头质量最大的节点将竞争成为簇头。通过理论分析和仿真对比表明,与LEACH算法相比该分簇算法降低了平均延迟,延长了网络生命期,并验证了该算法对动态拓扑具有适应性。     

带有重叠区域的多跳非均匀分簇路由算法

能耗作为衡量无线传感器网络性能的一项重要指标,通常将延长生命周期、均衡能耗作为网络协议重要的设计目标.针对静态、异构、非均匀分布的网络模型,设计带有重叠区域的分簇及簇内单跳、簇间多跳的路由算法 ----- OMU分簇路由算法,该算法中簇头不再作为数据转发节点,而主要用于簇内数据的接收与融合.通过综合考虑节点剩余能量、节点密度及与基站的距离进行簇头选举并进行分簇,形成簇间重叠区域,产生用于数据转发的中继节点.同时,建立簇头与中继节点轮换机制以达到节点能耗均衡的目的,并为每个节点建立能量最省的多跳数据传输路径.仿真结果表明,所设计的分簇路由算法,特别是在大规模部署的无线传感器网络中,能有效减少和均衡能量消耗.     

非均匀分布的无线传感器网络分簇路由算法

针对无线传感器网络(WSN)现有分簇路由协议中选举的簇头节点在监测区域内分布不均的问题,提出一种基于局部区域传感器网络节点分布数量控制簇头节点选举概率的算法HNDCRA。该算法通过对传感器网络检测区域的网格划分,计算出网格局部区域的传感器节点分布,并以此为依据确定传感器节点当选簇头的概率,来保证选举后每个网格都有簇头节点,且节点数量多的区域节点当选簇头概率较大,使得簇头随节点分布密度“均匀”,达到能耗均衡的目的。性能分析和仿真实验表明,与经典的LEACH协议相比,HNDCRA能够更好地将簇头“均匀”分布到网络区域,均衡全网能耗分布,提高能量利用率,从而延长网络生存时间。     

非均匀分布异构传感器网络动态多簇头成簇算法

延长网络寿命、提高监控质量是无线传感器网络成簇算法的重要设计目标,在对现有主要成簇算法进行研究的基础上,提出一种适应于节点非均匀分布环境下多级能量异构传感器网络的动态多簇头成簇算法.算法中,节点根据网络最优簇头数确定节点邻居感知半径.通过节点间的广播,每个节点获得感知半径内的邻居节点密度,节点根据邻居节点密度和节点当前能量确定节点成为主簇头的概率.根据主簇头的能耗,各簇独立判断是否选举辅助簇头以分摊主簇头的能耗.仿真结果表明,与现有主要成簇算法相比,新的成簇算法拥有更长的生存时间和更优的网络监测质量.     

通过功率控制建立密度自适应的分簇无线传感器网络

无线传感器网络的分簇密度是不定的,通过控制簇头发射功率将能使分簇密度控制在合理范围内.无线传感器网络的"簇头--成员"结构与CDMA的"基站--移动台"结构相似,可以采用CDMA的功率控制机制对无线传感器网络的最小ID分簇算法进行优化.改进后的算法和步骤得到了描述,并给出了控制簇头发射功率的流程图.     

应用相对变换的无线传感器网络分簇算法

针对无线传感器网络节点负载不均衡的问题,提出了一种应用相对变换的无线传感器网络分簇算法(RTCH)。在成簇阶段,节点将簇头剩余能量、簇头与节点和簇头与基站的传输能耗等参数利用该模型先进行相对变换,再计算簇头适宜度来选择加入簇头成簇,并通过簇头的反馈信息来控制簇的规模来优化网络性能。仿真实验结果表明,RTCH算法能更有效地均衡网络中的能量消耗,延长网络生命周期。     

传感器网络中基于节点密度的分布式成簇算法

在分簇路由协议中,延长传感器网络的寿命,很大程度上依赖于簇头节点选择的合理性。提出一种基于传感器节点分布密度的分布式成簇算法,该算法是对LEACH算法的改进,在选取簇头的时候除了考虑节点轮流成为簇头的问题,同时还考虑各节点的分布密度。仿真实验证明,新算法能比LEACH算法更有效地降低网络的能量消耗,均衡网络能耗水平,从而使得传感器网络的生命周期在LEACH算法的基础上有较大提高。     

一种抗干扰半静态分簇路由算法

针对无线传感器网络( WSNs)分簇路由算法中的能量洞、热点和抗干扰问题,设计一种抗干扰半静态分簇( AlSSC)路由算法,给无线传感器网络提供能量多、距离短、链路质量好的路径来传输数据.该算法利用节点定位获取节点地理位置,综合考虑传感器节点剩余能量和干扰信噪比,通过节点距离度量、节点聚簇、簇间融合、簇头选举和簇头轮换五个步骤进行无线传感器网络节点的分簇.仿真结果表明:这种路由算法可以提高无线传感器网络通信链路质量,均衡网络能量消耗.     

物联网无线传感器的网络分簇拓扑容错算法

无线传感网络是物联网的核心技术,其由部署在监测区域内大量的廉价微型传感器节点组成.节点除了感测特定的对象,还需要维持互相之间的网络连接.在传感器节点能量受限制情况下,良好的网络拓扑控制方法能够提升传感器网络的生存时间.因此合理地控制网络拓扑结构是当前无线传感器网络研究领域的热点和难点.提出了一种无线传感器网络分簇拓扑容错算法,利用主从簇头方式分摊簇头能量消耗,并采用候选簇头机制解决簇头失败.仿真实验证明该算法不仅具有较低的复杂度和较低的节点平均通信半径,而且具有较好的容错性能和较长的网络生命周期,可显著提高物联网的整体性能.     

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     

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.