一种能量有效的WSN路由协议

无线传感器网络中节能是首要考虑的问题。有效地延长无线传感器网络的生存时间,达到传感器节点的负载均衡是无线传感器路由网络路由协议的设计目标。由于LEACH协议存在在簇头节点的选举中未考虑节点的能量因素、簇头节点在空间上分布不均及所有簇头节点直接与Sink进行远距离数据传输过程中能量消耗过多等不足,本文提出了一种改进型的节能路由协议LEACH-ZED。LEACH-ZED采用区域划分的方式,综合考虑节点能量与到Sink节点的距离,进行簇间的多跳传输,大大改善了LEACH协议的一些缺陷。仿真表明,改进后的协议有效延长了网络的生存时间,降低了整个网络的能耗,从总体性能上看优于LEACH协议。     

一种基于簇首生成树的传感器网络分簇路由协议

针对无线传感器网络中分簇路由协议LEACH存在的不足,提出了一个以簇首最小生成树为簇间路由树的改进协议LEACH_CHMST。该协议摒弃了标准LEACH中簇首与sink采用简单单跳直接通信的策略,由处理能力相对较强的sink节点发现并生成覆盖全体簇首节点的最优路由树,并实现簇首到sink的多跳通信以节省节点通信能耗。实验仿真表明,与标准LEACH协议相比较,新的协议显著提高了网络的生存时间,节省了全网的节点能耗,特别适用于大规模无线传感器网络的应用环境。     

一种基于LEAC日协议的分簇路由算法

低能自适应聚类路由协议(LEACH协议)是为无线传感器网络设计的一种低功耗自适应分层路由协议,具有延长网络生命时间的作用.为了均衡无线传感器网络节点的能耗,延长整个网络的生命周期,通过对LEACH协议的研究,对簇首的选取和簇首与Sink的通信机制进行优化,提出了一种改进的LEACH协议的分簇路由算法.通过Madab仿真实验证明,改进后的LEACH算法在网络生命周期和网络能量消耗等方面比LEACH算法有较大的提高.     

基于布谷鸟搜索算法的无线传感器网络改进路由协议

为了解决无线传感器网络(WSNs)能量消耗不均衡,网络生存时间短的问题,在研究了几种现有路由协议基础上,提出一种基于LEACH协议改进的簇间多跳路由协议.该协议引入能量因子、密度因子和距离因子,修正了LEACH协议的阈值函数,并结合布谷鸟搜索算法对簇头集合进行了优化,同时提出新的路由机制,在簇头采用多跳方式和Sink节点进行数据通信.模拟实验表明:相比于LEACH协议,提出的新协议可以有效地均衡网络节点能量,延长网络生命周期.     

一种基于LEACH协议改进的簇间多跳路由协议

为了均衡无线传感器网络的能量消耗,延长网络的生存时间,在研究几种基于均匀分簇和非均匀分簇的路由协议基础上,提出一种基于LEACH协议改进的簇间多跳路由协议。该协议引入能量因子和距离因子修正了LEACH协议的阈值函数。在簇间通信过程,簇头节点与Sink节点之间采用多跳通信方式,簇头与簇头之间形成一条通向Sink节点的优化路径。实验结果表明,相比于LEACH协议和EEUC协议,本文提出的新协议能够有效的均衡网络的能量消耗,延长无线传感器网络的寿命。     

无线传感器网络分簇路由协议的改进研究

针对无线传感器网络(WSN)中分簇路由协议LEACH算法中簇首分配不均以及簇首与Sink节点直接通信问题进行研究,提出一种基于LEACH成簇思想的分簇路由协议。该算法基于节点剩余能耗和已担任簇首时间选举簇头。簇头间采用贪婪算法形成一条链,在该链中又选出一个簇头,将整个网络的数据融合后转发给基站。MatLab仿真结果显示,改进后的算法在均衡网络节点能耗和网络的生存时间上比LEACH算法有很大提高。     

一种能量高效无线传感器网络路由协议的设计

在无线传感器网络中提高节点能量问题的研究中,首先对无线传感器网络经典的分簇路由协议LEACH进行分析,针对LEACH中存在的少能量节点,或者偏远节点选为簇头节点,容易导致节点加快死亡、网络能量利用率降低的问题,通过改变簇头选择策略,综合考虑节点剩余能量和地理位置等参数的方法,提出一种新的路由协议,避免选取少能量节点为簇头.经NS2的仿真结果表明,提高了网络能量利用率.能量高效LEACH协议比LEACH原协议延长了28%的网络生存时间,并对延迟了第一节点死亡(FND)时间27%,并使得更多的能量利用于网络开始真正死亡之前,提高了网络能量利用率.     

一种基于散列链的自适应网格安全路由协议

LEACH(Low Energy Adaptive Clustering Hierarchy)路由协议是无线传感器网络拓扑控制中最具代表性和重要性的算法之一。针对LEACH路由协议簇头分布不均匀,节点死亡率高,易产生路由空洞及其所面临安全威胁等问题,提出一种基于散列链的区域划分网格自治安全路由协议LEACH-SEED。剔除低能量节点入选簇头的权利,改进簇头选举机制,簇头选举完成之后,每个簇头节点随机从散列链组成的密钥池中分配q个链密钥,其他节点利用单向哈希函数和伪随机函数生成通信密钥,网络遭受攻击后利用网格自治和待选簇头身份标识编号进行网络恢复。实验结果表明,改进的分簇算法能有效地降低节点死亡率,增强抗攻击能力,提高数据融合度,延长网络生存时间。     

WSN中一种能量均衡的分簇路由协议的设计

无线传感器网络中,LEACH协议是典型的分簇路由协议.文章针对LEACH协议的缺点,结合PEGASIS协议的优点,从簇首选择、簇的形成、簇间路由等方面对LEACH协议进行了改进,设计了一种能量均衡的分簇路由协议EBLP,并进行了仿真分析.仿真结果表明,EBLP协议节约了能量,平衡了能量消耗,延长了无线传感器网络的生存时间.     

一种WSN分簇路由协议研究和实现

近年来,我国兴建了众多基础设施,基础设施的健康监测直接关系着人们的生命和财产安全,也关系着基础设施的正常运行,因此研究面向基础设施健康监测的无线传感器网络分簇路由协议至关重要.目前已经有多个成熟平面路由协议和分层路由协议,但它们都存在传感器节点能量有限、结构简单等缺陷.为了延长网络寿命、提高信息传榆的可靠性,就需要对现有的路由协议做一些改进,以适应大规模的无线传感器网络.首先分析了设计无线传感器网络路由协议时面临的挑战,分类总结了典型的无线传感器网络路由协议及其优缺点;然后在详细分析LEACH协议的基础上,对LEACH协议在簇头节点选择和簇间路由方面进行改进,提出了面向基础设施健康监测的无线传感器网络分簇路由协议.将分簇优化算法和簇间多跳路由算法相结合,组成面向基础设施健康监测的无线传感器网络分簇路由协议.实验仿真表明,该路由协议有效地均衡了网络的能耗,推迟了多数节点的死亡,延长了网络的有效寿命.     

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.