基于有线长链解决传感器网络的能量空洞

研究了"能量空洞"现象,基于环模型,通过在网络中添加少量有线长链来缓解能量空洞,延长网络的生命周期.在环C2(环C2是半径为r2和r1的圆形重叠区域)内添加一些与sink直接相连的有线长链,将环C2内的部分数据通过有线长链向sink直接传送,从而降低了靠近sink节点的能量消耗.理论分析和仿真实验表明,该方法能够极大地延长网络的生命周期.     

基于蚁群优化解决传感器网络中的能量洞问题

基于多跳的无线传感器网络,越靠近sink的传感器节点因需要转发更多的数据,其能量消耗就越快,从而在sink周围形成了一种称为“能量洞”的现象.“能量洞”问题会导致整个网络由于内部节点能量过早耗尽而结束寿命,同时,网络中离sink较远的节点仍有大量能量剩余.研究“能量洞”现象,基于改进的分级环模型,总结出调节各环内节点的数据传输距离是实现网络节能的有效方法.证明搜索各区域最优的传输距离是一个多目标优化问题,即是NP难问题.从而提出一种基于蚁群优化的分布式算法,各区域根据其节点分布情况自适应地探索近似最优的传输距离,延长网络寿命.模拟实验结果表明,该算法在较短的时间内能够收敛到合理的解,并且得到的网络寿命接近于理想情况下的最优时间,与现有的类似算法相比,该算法提供了更长的网络寿命,并能适用于非均匀节点分布情况.     

基于小世界的传感器网络查询能量空洞问题

靠近Sink的传感器节点因为需要转发来自其它节点的数据而承担了更多的通信负载,这些节点往往更早地耗尽自身能量而有更短的生命周期,这种现象被称为“能量空洞”问题.文中基于小世界思想,通过向Sink节点添加一些长链,减少Sink周围节点转发数据的数量来缓解能量空洞的出现,从而延长网络的生命周期.首先对等距传输的网络进行了能耗分析,然后提出采用小世界的策略缓解能量洞的出现,从理论上分析了长链的位置和数量对能量消耗和网络生命周期的影响,提出了一种实用的小世界网络实现方法.仿真实验验证了理论分析结果.     

无线传感器网络中一种负载均衡的跳跃式路由协议

如何实现能量的高效利用,延长网络的生命周期一直是无线传感器网络研究的热点.在传统的路由协议中,靠近基站的节点由于要转发其它节点的数据容易过早耗尽能量而失效.本文基于传感器节点传输功率可调这一假设,提出了一种负载均衡的跳跃式路由协议(LBR).协议中每个节点维护K跳的路由表.在需要发送数据时,剩余能量较少的节点将数据发送给下一跳节点,而剩余能量较多的节点可以跨越多跳进行数据传输.从而均衡了节点的能量消耗.模拟结果表明,采用该协议建立的路由,不仅具有延时小,数据传送的路径长度短,维护简单等优点,并且能够改善网络的负载均衡,极大地延长网络的生命周期.     

负载相似节点分布解决传感器网络能量洞问题

基于多跳路由的传感器网络,靠近sink的节点由于要转发更多的数据,其能量消耗较快.能量消耗的不平衡导致了sink周围产生能量洞(energy hole),造成能量浪费,远离sink的节点还有大量的能量,但产生的数据不能传送到sink.研究了传感器网络的能量洞问题.在网络的连续空间状态下分析节点的负载分布特性,并研究空闲侦听(idle listening)对能量消耗的影响.基于分析结果,提出负载相似节点分布(load-similar node distribution)策略,即根据负载分布特性配置节点,负载重的区域配置较多的节点,以平衡各区域节点的能量消耗,解决能量洞问题.仿真结果显示,在不考虑空闲侦听能量消耗的情况下,与已有的一种非均匀节点分布和均匀节点分布相比,负载相似节点分布策略对网络寿命有显著改善;当考虑空闲侦听时,由于空闲侦听的能量消耗在总能量消耗中占较大比重,影响了网络寿命,但与其他两种节点分布策略相比,负载相似节点分布对网络寿命仍然有所改善.该分析模型和提出的负载相似节点分布策略可适用于其他多跳传感器网络.     

无线传感器网络解决能量空洞问题综述

基于无线传感器网络的特点,部分节点因为过早耗尽自身能量而导致网络原有覆盖区域缺失或者数据无法送达sink节点,从而形成能量空洞现象。如何避免能量空洞并能有效延长网络周期,是目前无线传感器网络的研究热点。当前解决能量空洞问题主要是以最大限度地均衡网络负载为设计目标。从5个方面,即能量控制与功率控制、数据压缩与融合策略、节点非均匀分布、动态性及增加sink节点数量和分簇算法,总结了解决此问题的方法,同时分析了各种方法的优缺点及进一步研究的方向。     

能量高效的无线传感器网络动态分簇算法研究

为了提高无线传感器网络的能量利用率和延长网络的生命周期,提出了基于地理位置的能量高效的动态成簇算法(GL-DC),在簇的建立阶段,采用非均匀分簇方法,解决了簇首能量消耗不均衡问题。在网络运行过程中,采用基于剩余能量和距离来动态生成新的簇首,避免了靠近SINK节点的簇头因转发大量数据而过早耗尽能量。仿真实验结果表明,该方法具有更好的性能,与EADEEG、LEACH和PEGASIS等路由协议相比,GL-DC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。     

粒子群优化的无线传感器网络仿真研究

研究优化无线传感器问题,针对延长传感器网络的寿命,保证簇的平均分布,提高簇的负载均衡,从而减少能量消耗.传统算法在确定簇首过程中由于忽略了邻居节点的状态信息,容易导致簇内节点过早的出现盲节点现象,从而降低网络的生存时间.要解决上述问题,延长网络生命周期和有效降低能耗,提出一种粒子群优化的无线传感器分簇算法.在充分考虑了簇内邻居节点的能量和距离分布信息的前提下,通过粒子群优化分簇和簇首选择,并进行仿真.仿真结果表明,与LEACH算法相比,算法能有效地均衡网络节点的能量消耗和显著地延长网络寿命,并有效地避免了盲节点现象的过早发生.     

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.     

一种基于长链竞争机制的传感器网络能量空洞研究算法

在无线传感器网络中,越靠近Sink的节点由于承担更多子孙节点的数据转发,能量消耗越快,极易形成“能量空洞”,大大缩短了网络生命周期。针对能量空洞的问题,提出一种基于长链竞争机制的k-leader算法以延长网络生命周期。k-leader竞争算法将Sink一跳范围内节点的一部分数据量交给距离Sink一跳距离以外两跳范围以内的节点,通过长链直接发送给Sink节点,从而减轻Sink周围节点的负载。同时,k-leader的置换算法又保证了节点能够根据能量损耗的情况轮换担任leader节点和通过长链发送数据的节点,达到能量消耗均衡的目的。分析了leader节点的数量k的优化取值,并通过仿真验证了k-leader算法在网络生命周期、网络能耗均衡等指标上的性能。     

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。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。