无线传感器网络中改进的DV-Hop算法

针对传统DV-Hop算法中定位精度低的问题,该算法从三个方面进行改进,（1）设置距离发射端标准一跳时节点所接收的接收信号强度指示（RSSI）值,利用节点接收信号的RSSI值与设置的RSSI值之间的比来修正跳数。（2）将未知节点的平均跳距分两段考虑,使未知节点到锚节点的估计距离更精确。（3）构造校正向量,对未知节点的估计坐标进行校正。仿真实验表明改进算法的定位精度明显高于传统DV-Hop算法和文献[6]基于RSSI比值修正的算法,稳定性也有一定的提升。     

基于RSSI比值修正的无线传感器网络DV-Hop定位算法

针对传统原DV-Hop算法未考虑因邻居节点间分布不均直接使用跳数来估计每跳距离而导致对未知节点到信标节点的距离估算造成较大的误差,提出一种基于接收信号强度指示(RSSI)比值修正距离估计定位算法,把RSSI作为节点间欧氏距离的比征来修正每一跳的距离.仿真实验表明:该改进算法在几乎没有增加通信开销的前提下有效地提高了DV-Hop定位精度,同时增强了算法的环境适应性.     

基于节点RSSI值与临界RSSI比例的跳数修正和跳距重估的DV-HOP算法

为了减少传统DV-Hop定位算法对未知节点定位时产生的较大误差,提出了一种基于节点RSSI值与临界RSSI比例跳数修正和跳距重估的DV-HOP算法。首先,采取节点RSSI值与临界RSSI比例来修正跳数,得到修正后的跳数;然后利用修正后的跳数求解跳距均衡系数对平均跳距进行穷尽三角组合加权修正,得到修正后的跳距;最后,将修正后跳距与通信半径进行比较,偏差最大和最小的跳距不参与计算,再求剩余跳距值的均值得到平均每跳距离。仿真结果表明：在相同的网络环境下,与经典的DV-Hop算法相比,文中算法仅需要节点通信芯片具有RSSI指示功能,并不需要其它额外的硬件,有效降低了定位误差;与其他DV-Hop修正算法相比,该算法同样也具有降低定位误差的优势。     

基于RSSI测距和DV-HOP误差修正的WSN节点定位

针对DV-Hop算法定位精度受节点分布均匀度影响较大的问题,设计了一种基于RSSI测距和DV-Hop误差修正的传感器节点定位算法;首先采用RSSI接收信号强度值实现对跳数加权,以更好地反应跳段之间的间距;然后通过RSSI对锚点之间的距离进行测距,通过引入平均每跳误差,改善原有的锚点跳距计算方法,使得修正后跳距误差较原有方法大为降低;仿真实验表明,文中方法在节点非均匀分布且不增加硬件设备前提下,大大提高了定位精度,与文献[8]和传统DV-Hop算法相比,其定位误差分别降低了37.8%和25.5%,具有很强的实用性。     

融合RSSI跳数量化与误差修正的 DV-Hop改进算法

为了提高DV-Hop算法在非均匀网络中的定位精度,提出一种基于RSSI跳数量化与误差修正的DV-Hop改进算法。改进算法首先利用节点间RSSI值与基准RSSI值的比值量化节点间跳数,使整数跳数转化为连续跳数,并在量化跳数的基础上对锚节点平均跳距进行重估,然后对各锚节点平均跳距进行加权处理以修正未知节点平均跳距。最后利用未知节点与最近锚节点的距离关系对未知节点坐标的估计误差进行修正,以进一步降低节点的定位误差。实验结果表明,相较于DV-Hop算法及相关文献,改进算法在相同的网络环境下能够有效降低累积误差对距离估算的影响,提升未知节点定位的精度,在不增加硬件开销的情况下,改进算法的相对定位误差比DV-Hop算法平均下降了20.7%。     

基于跳数修正与LM优化的DV-Hop改进算法

针对DV-Hop定位算法在节点分布不均匀的传感器网络拓扑环境下,跳数与跳距估计存在误差的问题,提出了一种名为ILDV-Hop的改进算法。首先基于信标节点间估计距离与真实距离的差值,提出了一种全网络的有效跳距。其次在信标节点与未知节点间多跳计算过程中增添了修正值,同时利用接收信号强度指示(RSSI)值优化单跳值的大小。最后采用列文伯格-马夸尔特算法估计未知节点的最优位置。仿真结果表明,与传统DV-Hop算法以及基于拟牛顿迭代的DV-Hop算法相比,ILDV-Hop算法的定位误差分别减小了23%与10%左右,定位精度有了显著的提高。     

基于RSSI跳数修正的DV-Hop改进算法

针对原始DV-Hop算法中跳数值不能反应出节点间实际距离大小而导致拓扑不规则网络中节点定位误差较大的问题,提出了一种基于接收信号强度指示RSSI(Rceived Sgnal Srength Idicator)的改进算法。首先根据直接邻居节点接收到的RSSI值对第1跳进行分级,细化跳数;同时把节点间的距离比值作为权值,并将其转化为相应RSSI的关系对跳数进行加权修正,使获得的跳数值更准确。仿真结果表明在相同的网络环境下,与传统算法相比改进算法在不增加额外硬件的前提下有效地提高了定位精度。     

基于RSSI测距的DV-Hop算法

由于DV-Hop算法在不均匀网络中节点定位精度不高,以及RSSI算法受环境因素影响较大,将RSSI算法与DV-Hop算法相结合,提出一种利用RSSI测距技术改进DV-Hop的算法-----BRDV-Hop算法.该算法应用RSSI测距技术,定义信标节点的平均跳距误差,并利用信标节点的平均跳距误差对未知节点与信标节点之间的距离进行修正,从而达到减小定位误差的目的.仿真结果表明,与标准的DV-Hop算法相比,在不增加传感器节点硬件的基础上,改进算法能有效降低定位误差.     

基于弹簧系数的无线传感器网络定位算法

提出了基于弹簧系数和接收信号强度指示的DV-Hop的改进算法(SCRDH)。将节点与锚节点间最短路径抽象成弹簧模型,利用弹簧模型改进DV-Hop全网平均跳距和节点之间最小跳数的取值方法,并通过增加全网弹簧系数来提高定位精度。仿真结果表明:SCRDH算法的定位误差在一定条件下可以达到12%明显优于DV-Hop算法。     

基于跳数修正和遗传模拟退火优化DV-Hop定位算法

针对DV-Hop算法在跳数和平均跳距方面误差较大的缺点,提出了基于跳数修正和遗传模拟退火优化DV-Hop定位算法.该算法对未知节点的跳数进行改进,通过已知节点的精确跳数,计算偏差系数对其增加修正值;采用遗传算法和模拟退火算法相结合的方法在平均跳距值方面进行优化.通过仿真实验结果分析,改进后的算法能够明显提高节点定位精度.     

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.