基于锚节点选择的无线传感器网络定位算法

针对无线传感器网络定位系统中节点随机分布及锚节点数量有限而影响定位性能.在传统的DV-Hop定位算法基础上提出并分析一种基于锚节点选择的无线传感器网络定位改进算法.首先,根据距离矢量路由技术获得节点到锚节点间的距离.然后,选取合适锚节点进行初始位置估计,并进行位置优化.最后,将其升级为锚节点从而提高锚节点密度.仿真结果表明该算法与传统的DV-Hop定位算法相比定位精度有很好的改善,具有一定的可用性.     

基于改进单锚节点的无线传感器网络节点定位算法

节点定位是无线传感器关键技术之一。针对固定多锚节点方法定位精度低的缺陷,为了提高无线传感器的定位精度,提出一种基于改进单锚节点的无线传感器网络节点定位算法(SFOA-SVM)。首先采用单移动锚节点在无线传感器网络中移动,构建无线传感器定位模型的学习样本,然后采用SVM构建节点定位模型,并采用渔夫捕鱼算法模拟渔夫捕鱼行为找到最优SVM参数,最后采用仿真实验测试节点的定位性能。结果表明,相对于其他定位算法,SFOA-SVM提高了无线传感器节点的定位精度,具有一定的实际应用价值。     

面向无线传感器网络节点定位的移动锚节点路径规划

节点定位是无线传感器网络技术研究的一个基本问题,大多数无线传感器网络的应用和中间件技术都需要节点的位置信息.目前比较实用的定位方法是利用一些移动锚节点(如安装有GPS)根据有效的规划路径移动,通过发送包含其自身坐标的信息来定位其他节点,该方法不过多地增加无线传感器网络成本,还可以获得较高的定位精度.在该方法中,移动锚节点的路径规划问题是需要解决的基本问题.主要研究移动锚节点的路径规划问题,把图论引入到无线传感器网络节点定位系统.把无线传感器网络看成一个连通的节点无向图,路径规划问题转化为图的生成树及遍历问题,提出了宽度优先和回溯式贪婪算法.仿真实验和真实系统实验结果表明,该方法能够很好地适应无线传感器网络节点随机分布的节点定位,可以取得较高的定位精度.     

基于虚拟节点的BP无线传感器网络定位算法

无线传感器网络中节点的准确定位是网络应用的支撑技术之一.针对网络中锚节点比例因素,提出了基于BP神经网络的次锚节点的定位算法,虚拟地增加网络中用于定位的锚节点的个数,并提出了引人虚拟节点的方法寻求较佳的次锚节点,从而提高了定位精度.该方法不依赖于节点间的距离,并利用了神经网络的并行性,因而算法简便快速,硬件结构实现简单.仿真结果证明了利用虚拟节点确定次锚节点的有效性,同时表明BP神经网络定位算法和次锚节点的引人可大大提高网络未知节点的定位精度,减少无线传感器网络的成本.     

基于线性参数加权评估机制的无线传感器网络节点定位

为解决无线传感器网络节点定位过程中拓扑计算复杂,且因随机误差因素导致定位精度不高等问题,提出一种新的无线传感器网络节点定位算法。评估接收到的锚节点信息,根据线性参数评估机制对待定位网络节点的位置进行初步估计,计算线性参数数值,搜寻到最佳的锚三角,使用加权评估方式,利用不同锚节点的三角定位参数进行多次加权平均计算,以获取节点的准确位置信息。仿真结果表明,与DV-hop算法、DV-distance算法相比,该算法的定位精确度更高,其定位过程中的误差更低。     

基于三边定位的WSN锚节点加权补偿算法

为了有效抑制复杂环境对无线传感器网络节点定位精度的影响,以三边定位算法为基础,提出了一种锚节点加权补偿定位算法.该算法利用锚节点自身的定位功能,通过加权质心方法获得定位系统在锚节点附近的区域定位误差,并对该误差进行补偿,从而提高该区域盲节点的定位精度.实验结果显示,该算法简单有效,具有普遍应用意义.     

基于遗传算法WSN节点定位算法研究

研究无线传感器网络节点定位问题.针对无线传感网络由于位置信息等原因而造成节点定位误差较大,精确度不高等问题缺陷,提出了一种改进的基于遗传算法优化DV-hop定位算法,并将算法应用在无线传感网络节点定位中,算法首先利用节点间的距离和锚节点的位置,在距离无关定位算法的最后一个阶段,采用遗传优化算法对DV-hop算法定位得到位置进行校正,在不增加传感器节点的硬件开销的基础上有效提高定位精度和扩大定位范围,仿真结果表明,改进的网络节点定位算法定位误差小和定位范围广等性能,与原始的DV-Hop定位算法相比定位误差明显减小,精度明显提高.表明算法是一种高效节能的定位算法.     

无线传感器网络节点自定位技术

节点位置信息是许多无线传感器网络应用的基础,节点自定位技术在无线传感器网络中具有重要地位。目前已经出现了各种节点定位算法,其中的KPS算法不需要锚节点和复杂的测距技术,具有一定的优越性,但当网络部署在非理想的环境中时,存在定位精度较低的问题。该文针对这一问题,提出了利用运动学定位方法对KPS算法中的参考节点位置进行修正,从而提高节点定位精度。仿真结果表明,改进算法能够明显提高非理想环境中的节点定位精度。     

基于RSSI的无线传感器网络节点定位算法

节点定位技术是无线传感器网络关键技术之一,介绍了节点定位技术的基本原理,提出了一种新的基于接收信号强度(RSSI)的无线传感器网络定位算法.该算法在第一阶段对节点初始位置进行初步估计,第二阶段对节点初始位置进行求精.仿真结果表明,在锚节点比例较低的情况下,该算法仍然可以实现较高的定位精度,并且与dv-distance定位算法比较,表明该算法在相同条件下精度更高.     

基于蛙跳算法的无线传感器网络节点定位

为减小测距误差对无线传感器网络定位精度的影响,将蛙跳算法应用到距离式定位算法的位置计算阶段中,提出了蛙跳定位算法。该算法在适应度函数设计中,根据节点间的测距信息对锚节点进行了加权处理,以降低测距误差对定位结果的影响。结合最小最大法构造初始种群,使其包含更多可行解,从而提高算法效率。仿真结果表明,与采用极大似然估计法或总体最小二乘法来进行位置计算的距离式定位算法相比,该算法有效降低了距离误差对定位精度的影响,具有较高的定位精确度和稳定性,是一种实用的无线传感器网络节点定位方法。     

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.