基于均值漂移和联合粒子滤波的移动节点定位算法

针对无线传感器网络移动节点定位面临的高精度和实时性要求,把均值漂移算法引入联合粒子滤波(Joint ParticleFilter)框架.提出了基于均值漂移和联合粒子滤波的移动节点定位算法.它使用均值漂移算法构建粒子滤波的建议分布,通过有效利用最新观测信息,提高粒子状态估计的准确性,使得采样粒子的状态分布与后验概率分布更接近,减少了状态估计必需的粒子数目.该算法还提出了基于虚拟海明距离和交互势的权重计算方式,减少相邻移动节点间的干扰.仿真实验结果表明,基于均值漂移算法和联合粒子滤波的移动节点定位,可获得比基本粒子滤波更高的定位精度,其定位精度与无味粒子滤波(Uscented Particle Filter)相当,而计算开销比无味粒子滤波减小至少50%.     

基于运动参数预测的群组移动节点定位算法

针对群组移动节点定位算法普遍基于不切实际的假设,存在普适性欠佳和精度不高的问题,提出一种基于运动参数预测的群组移动节点定位算法。该算法根据群组移动节点具有相似运动的特点,运用Hermite 插值多项式预测、过滤节点运动参数。为确保定位精度,应对节点移动性带来的采样区域变化,运用预测节点运动参数构建粒子有效采样区域;为节省时间开销,基于采样粒子真实分布与其极大似然估计值之间的最大K-L(Kullback-Leibler)距离确定能够满足不同采样区域的最少粒子数目;为改善算法收敛性,运用预测运动参数创建滤波公式,并选取优质粒子参与节点位置估计。在与经典算法MCL（Monte Carlo Localization）法和加权最小二乘法的Matlab对比实验中,分析了节点移动速度、自由度、K-L距离阈值、采样方格边长对定位精度的影响。结果表明,较上述算法,本算法的定位误差和时间开销较小,无需锚节点辅助,普适性较好。     

基于采样滤波的信号矢量分解移动定位算法

以接收信号强度(received signal strength,简称RSS)的测距技术为基础,借助移动传感器网络(MSN)中MCL类粒子滤波定位算法的采样、过滤方法,并融入物理中力的分解和合成的思想,提出了一种信号矢量分解的采样滤波移动节点定位算法.该算法通过建立直角坐标系,分解合成移动节点、样本点与信标节点间的信号矢量,利用误差圆环采样,比较移动节点与样本点的信号合矢量进行滤波,将合矢量模差绝对值最小的样本点坐标的均值作为移动节点的坐标.仿真结果表明,在同样的实验条件下,该算法的定位精度明显高于相比较的其他算法,且该算法不需要添加额外的硬件设备.     

基于RSSI和改进MCL算法的移动节点定位跟踪设计

由于传统节点定位方法大多针对静止传感器网络,不能适用于网络结构和节点位置动态变化的移动传感器网络,提出了一种基于RSSI测距和改进的MCL(Monte Carlo Localization)算法的移动传感器节点定位跟踪方法;首先描述了经典MCL算法和接收信号强度RSSI测距方法,然后设计了一种改进的MCL算法,将传统的MCL方法预测粒子位置的过程即预测和滤波两个阶段,更新为锚节点TTL受控泛洪方式广播自身位置、采用拉格朗日插值法预测节点下一时刻的位置和速度、求取锚盒采样区域、k跳锚节点粒子滤波和根据预测下一时刻的节点位置和速度与当前时刻的位置信息确定各粒子权重的5个阶段;采用仿真器MCL-Simulator进行仿真,结果证明:文中方法能有效实现移动节点的定位,与其它方法相比,具有较小的平均定位误差,具有很强的可行性。     

基于动态网格划分的移动无线传感器网络定位算法

定位技术是无线传感器网络中关键的基础支撑技术,目前提出了许多静态网络的节点定位算法,移动无线传感器网络的定位研究相对较少.针对定位节点和参考节点随机运动的网络模型,提出了一个基于动态网格划分的蒙特卡罗定位算法.算法中当接收的参考节点数超过一定阈值时使用最远距离节点选择模型,选出部分参考节点参与定位和信息转发,节约能耗.接着基于选择的或所有接收的参考节点构建采样区域,进行网格划分,使用网格单元数计算最大采样次数,在采样区域内采样并使用误差补偿的运动模型进行过滤,提高了采样效率,减少了计算开销,并保证了较好的定位精度.仿真实验表明算法在定位精度,计算开销、能耗等方面都具有较好的性能.     

基于改进的洪泛广播和粒子滤波的无线传感器网络节点定位

针对目前移动无线传感器网络定位问题存在的不足,提出了一种基于改进的洪泛广播机制和粒子滤波的节点定位算法。对于一个给定的未知节点,首先采用改进的洪泛广播机制,从离它最近的锚节点得到的有效平均跳距来计算出它到它的所有邻居节点的距离。然后采用一种差分误差校正算法,以减小平均跳距中由于多跳累积造成的测量误差;其次,采用粒子滤波和虚拟锚节点来减小预测区域,得到更有效的粒子预测区域,从而进一步减小对未知节点位置的估计误差。仿真结果表明,所提算法与定位算法DV-Hop、蒙特卡罗Baggio（MCB）和基于测试的蒙特卡罗定位（MCL）相比,能够有效地抑制冗余广播和减小与节点定位相关的消息开销,以较低的通信成本实现较高精度的定位性能。     

陪护机器人粒子滤波定位法中重采样算法研究

针对室内陪护机器人粒子滤波定位方法,研究了四种粒子滤波重采样算法:多项式重采样算法、残差重采样算法、分层重采样算法和系统重采样算法,并分别对其进行仿真比较.实验证明残差重采样算法粒子收敛速度和粒子匮乏程度取折衷,性能优于其它三种重采样算法,在此基础上利用仿真实验结果在HHR-0303服务机器人上进行了实验.实验证明采用残差重采样算法的粒子滤波算法,利用声纳配合里程计定位的方案能达到定位目的.     

基于仿生算法改进粒子滤波的SLAM算法精度预测

为解决传统粒子滤波算法重采样时产生的样本退化及样本贫乏带来的机器人定位与建图精度下降问题,提出一种基于改进仿生算法的粒子滤波.该算法将粒子最新时刻的观测与状态信息引入亮度公式,并将萤火虫的优胜劣汰和位置更新机制融入粒子滤波算法,以提高粒子的滤波能力.为保证算法的收敛速度和预测精度,在萤火虫位置更新过程中引入自适应调整步长进行即时修正;基于标准粒子滤波重采样的缺陷,采取分步重采样策略,通过偏差修正指数加权算法制定高效的舍小保大方案,并合理使用剩余大权值粒子完成粒子的复制和添加.仿真验证表明,所提出的改进算法可以明显提高传统粒子滤波的预测精度,且应用到基于移动机器人运动模型的定位与建图时可保持较高的定位精度和较好的稳定性.     

基于蒙特卡洛方法的移动传感网节点定位优化算法

无线传感器网络正在被应用到各种各样的监测环境中,在这些应用场景中,传感器节点的位置信息大都是至关重要的.目前对传感器节点定位方面的研究大都只针对静态WSN的情况,对于移动WSN节点定位的研究仍然十分有限.该文提出了移动WSN中节点间互相优化定位的新思路,通过判断式筛选出定位精度高的节点,并协助其他节点进行定位条件的优化.所提出的算法TSBMCL通过更精确的裁剪待定位节点的蒙特卡洛盒,并增加节点的粒子滤波条件来实现节点的精确定位.大规模的仿真结果表明,该算法可精确的锁定节点位置区域,高效的采样得到节点的位置样本,相比于传统的移动WSN蒙特卡洛定位方法,大大提高了节点的定位精度.     

基于粒子滤波的移动物体定位和追踪算法

提出一种基于粒子滤波的目标定位算法PFTL(particle filter based target localization)以及一种基于网络覆盖问题的节点组织策略SAC(sampling aware tracking cluster formation).PFTL 的基本思想是,采用一系列带权粒子(weighted particles)来预测移动物体位置的后验分布空间,每个新时刻根据传感器的测量数据来权衡和定位目标.PFTL 通过引入误差容忍(error tolerant)的方式来存储和发送目标位置数据,使汇聚点关于物体位置信息的数据误差在一个可控的范围内,进而极大地减少网络通信负荷.SAC基于传感器采样离散化的特点来制订数据融合策略,并以最大化覆盖物体运动轨的方式动态地选取节点和进行节点簇的有效组织.模拟实验结果表明,与现有的几种定位算法和追踪协议相比,结合PFTL 算法和SAC 策略能够以较小的代价取得更好的定位效果和网络负载均衡,进而延长网络寿命.     

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.