基于RSSI等级的蒙特卡罗定位算法应用研究

感知节点的定位是无线传感网应用的基础。现有的静态定位算法无法应用于动态传感网。针对一类目标节点移动而锚节点静止的传感网应用,提出了一种RRMCL（RSSI Rank Monte Carlo Localization）定位算法。该算法以蒙特卡罗算法为基础,利用RSSI（Received Signal Strength Indication）值与距离的单调递减关系划分通信域,减少采样区域大小。为了避免锚节点共线出现定位失效的情况,引入共线影响角度,提出了一种约束策略。仿真结果表明,提出的RRMCL与现有的MCL和MCB定位算法相比,能有效缩小采样区域,提高了定位精度和速度。     

无线传感器网络中一种移动节点定位算法

无线传感器网络中现有的大多数定位算法都是针对静态节点的,不能应用于节点移动的情况.本文提出了MCBE(Monte Carlo Localization Boxed Using Estimation)移动定位算法,该算法利用锚盒子(Anchor box),即包含待定位节点可能位置且平行于坐标轴的矩形以及非锚节点位置来帮助定位.锚盒子大小和定位误差存在正相关关系,算法根据待定位节点的一跳和二跳锚节点位置计算出锚盒子大小,当锚盒子大于一定值时,利用锚盒子小的非锚节点位置缩小锚盒子,最后在锚盒子范围内对位置采样,用蒙特卡罗MCL方法定位.理论分析和仿真结果表明,MCBE能有效地缩小采样区域,提高定位精度.     

使用历史锚节点信息的改进MCB算法

针对MCB算法的采样效率及定位误差,在锚节点静止而未知节点运动的情况下,提出了一种新的改进算法MBHA,通过充分利用侦测到的历史及当前锚节点信息,来修正MCB算法的采样箱。大数据量仿真结果表明,修正后的采样区域相比修正前更接近节点的真实位置。MBHA算法最终使用优化修正后的采样区域进行采样,在绝大多数的对比仿真环境实验中,该算法既大幅提升了采样效率,又提高了定位精度。     

移动无线传感网中的迭代蒙特卡罗定位算法研究

研究移动无线传感网中的节点定位问题,分析影响蒙特卡罗定位精度的两个因素:观测值和前一时刻的位置样本集,提出一种迭代蒙特卡罗定位算法。该算法中,信标节点的位置信息在每个时间段只被它的邻居节点转发一次,但是接收到该信息的其他节点会保存它们,并在下一时间段将它们与待发送/转发的信息融合成一个数据包进一步转发,增加待定位节点用于估算前几个时间段位置样本集的观测值。待定位节点再利用蒙特卡罗算法迭代计算前面时间段的位置样本集,并充分利用观测值滤除较差样本,从而提高当前时刻的定位精度。仿真实验表明改进算法提高了定位准确度。当信标节点密度较低时,更能体现改进算法的优越性。     

WSN中改进的MCB移动节点定位算法

考虑到蒙特卡洛盒移动节点定位算法中存在的定位精度低的缺陷,提出一种改进的基于RSSI的MCB定位算法。该算法依据节点接收的RSSI值缩小锚盒子区域;利用二次牛顿插值法预测节点运动轨迹,估算移动速度,进一步获取有效采样区域;然后依据采样盒大小自适应确定采样个数,避免多余样本的采集;最后借鉴遗传算法中交叉和变异思想优化采集过程。实验仿真结果表明在不同锚节点密度情况下,改进后的移动节点算法的定位精度始终优于传统MCB算法。     

一种基于CKF的无线传感器网络分布式定位算法

为提高无线传感器网络节点定位的精度,降低算法计算复杂性,提出了一种基于容积卡尔曼滤波的无线传感器网络分布式节点定位算法。该算法假定移动锚节点按预定路径在传感区域移动,并周期性广播自身位置信标信息;每个未知位置节点首先收集多个锚节点信标信息及信号强度信息,然后估算出锚节点信标位置与未知节点的距离,最后在未知节点上运用容积卡尔曼滤波算法完成自身位置的分布式定位。仿真结果表明：本文所提算法具有优良的定位性能,定位精度和无迹卡尔曼滤波算法相当,明显优于极大似然估计定位算法,而计算复杂性则低于无迹卡尔曼滤波算法。     

多功率锚节点辅助的DV-Hop定位算法

在无线传感器网络中,DV-Hop定位算法在计算未知节点到锚节点的距离以及通信半径之内相邻节点跳距时存在较大误差,提出了一种锚节点辅助的分布式定位算法。此算法不需要任何测距技术支持。它是利用锚节点的功率控制,即以不同的发射功率发射信标信号,接收到信标信号的未知节点将这些信标信息记录。此外还考虑了用全网锚节点来修正单独锚节点的平均每跳距离,用极大似然法计算节点坐标。Matlab仿真实验结果表明,在相同网络环境下,该算法能有效减小距离计算带来的定位误差,可适合实际定位情况且具有较高的定位精度。     

基于IMCB算法的无线传感器网络节点定位

针对蒙特卡洛盒(MCB)移动定位算法中存在的样本点退化问题,提出一种改进的蒙特卡洛盒(IMCB)定位算法,将其应用于无线传感器网络节点定位中。在MCB算法的基础上,通过分析当前时刻定位结果、节点距离以及相对位置信息,获得下一时刻在样本盒不同区域的采样概率,使样本点尽可能落在后验概率较大的区域内,从而解决MCB算法样本点退化导致定位精度降低的问题。仿真实验结果表明,在相同条件下,与MCB、MCL算法相比,IMCB算法的平均定位精度提高约14%,平均定位能耗降低约17%。     

非合作信标条件下水下无线传感网可靠定位技术

传统假设水下无线传感器网络的传感器节点和信标节点都是合作的,但是在军事应用等特殊场合下,某些节点容易被敌方捕获或入侵,因而水下无线传感网络中有时会存在一些非合作的恶意节点。针对存在若干非合作信标的水下无线传感器网络定位应用,提出了一种非合作信标节点约束下水下无线传器网的可靠节点定位算法。本文算法利用一跳邻居范围内信标节点独自投票机制实现对非合作信标的判决与剔除,从而减少由于存在非合作信标节点对定位误差的影响,同时也分析了不同比例非合作信标下的定位误差界限。仿真结果验证了本文提出的算法相比传统定位算法,在平均定位精度和定位覆盖率等方面都有所提高。     

移动无线物联网感知层传感控制定位算法研究

为了提高感知层传感控制定位的准确性和稳定性,提出移动无线物联网感知层传感控制定位算法.以DV-hop定位算法获取的移动无线物联网感知层通信区域内所有节点到各个锚节点的距离和跳数信息为基础,提出了基于跳数修正的DV-hop定位算法,对锚结点间跳数和未知结点跳数进行修正,计算出每个锚结点与各结点之间的距离,利用二维双曲线定位算法得到未知结点的位置坐标,实现移动无线物联网感知层传感控制定位.实验结果说明:所提算法在不同总节点个数和节点通信半径下定位误差始终保持最低,稳定性强;当跳数修正系数为2时该算法的定位精度最高,效果最佳;可选择较大的锚节点比例和较小的偏离因子,进一步提升定位效果.     

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.