物联网中基于RFID的移动标签定位方案

当前基于RFID的定位系统无法使用异构移动阅读器按照分布式策略定位移动标签,且定位精度低下。针对这种情况,提出了LSMT-RFID系统。该系统使用一组异构移动式RFID阅读器来定位移动RFID标签,移动阅读器通过时间约束交错过程展开合作,附近的阅读器通过共享询问信息来相应地估计标签位置,并使用主动和被动协议来确保位置信息的及时传输。基于ns-3的仿真实验来评估方案的定位能力,重点考察了平均定位误差和定位延时。实验结果表明,本方案能实现有效定位。     

多径环境下无源超高频RFID定位算法研究

随着物联网技术的发展,无源超高频无线射频识别(UHF RFID)定位技术的应用环境日益扩大。但在室内复杂多径的信道条件下,其定位精度往往由于多径干扰而大幅下降。为此,对多径环境下的无源RFID进行定位误差分析,并根据误差模型提出一种基于多维标度的RFID定位算法。利用阅读器获取参考标签和定位标签的相位差,通过相位差构建参考标签和定位标签之间的距离矩阵,并采用多维标度方法获取定位标签的位置信息。仿真结果表明,在存在较强直视路径的多径环境中,该算法仅使用少量的参考标签即可有效对抗多径干扰。     

基于视频辅助的无源RFID室内跟踪技术

室内跟踪定位技术中,RFID技术造价低、无接触、识别快速,成为室内跟踪定位的主要选择。本文采用无源RFID跟踪,通过信号强度信息推知目标和参考标签的距离,给出目标的位置估计,然后结合网络摄像头在可见区域通过视频图像辅助对跟踪目标进行精确定位,并给其在绝对坐标系中的坐标。最后将目标与RFID标签坐标位置相比较,得到正确的目标位置和ID。     

基于无源超高频RFID温度标签的温度监测系统

设计一种基于无源超高频(UHF)射频识别(RFID)温度标签的温度监测系统.系统由课题组自主研发的无源超高频RFID温度标签、Speedway R220商用阅读器和上位机应用软件组成,实现了物品身份识别、温度实时测量和显示的功能.为提高温度标签的测温精度,提出了一种自适应功率匹配算法,使得天线扫描范围内的多个标签都能在最佳测温功率下测温.测试结果表明:当温度标签与阅读器天线的距离分别为0.5,1.0,1.5m时,测温误差小于±1℃.     

基于动态ID带搜索密钥的RFID认证协议

针对射频识别（RFID）认证协议安全性较差的问题,设计一个基于动态ID带搜索密钥的RFID认证协议。标签利用单向hash函数的部分输出更新搜索密钥和ID。分析表明,该协议能够有效地实现标签与阅读器之间的相互认证,同时能够抵抗包含前向安全、后向安全、位置跟踪在内的多种攻击,而且硬件需求不高,适合低成本标签使用。     

基于TDOA的有源RFID定位系统

设计并实现了采用MSP430单片机和CC1101射频芯片,基于超声波和射频到达时间差的低功耗、高精度的室内定位系统,用于待定位标签的定位和追踪。系统主要采用超声波收发分离的方式,电子标签首先发送射频信号探寻信号范围内的阅读器数量,确定阅读器的数量后,再给阅读器发送一个射频信号,发出射频信号的同时,发送超声波信号,阅读器启用定时器计算接收到射频信号与超声波信号之间的时间差,并将数据传送给中心控制主机,控制主机通过三个圆相交于一点的方式计算出待定位标签的位置,并通过MFC程序图形化显示出来。实验结果表明,该系统具有较高的定位精度。     

快速检测RFID复制标签的算法研究

针对大型的RFID系统中使用标签ID无法识别具体复制标签的问题,提出了一种快速检测复制标签的CTDA算法。首先,标签内存储[k]个哈希函数,标签在接收到阅读器的查询帧后多次回复阅读器构造虚拟克鲁姆过滤器,找到阅读器通信区域内的标签集合[M];然后,[M]中标签通过多轮哈希运算使得阅读器构建时隙状态向量,目的是给每个标签分配单一时隙;最后,标签向阅读器回复10 bit信息,阅读器通过检测各个时隙是否由单一时隙变成冲突时隙来判断标签是否受到复制。经过仿真分析,证明该算法在执行时间上优于Bu K提出的GREAT算法和Qiao Yan提出的轮询协议RIP算法。     

基于相位差测距的RFID室内定位系统设计

针对当前室内定位的广泛需求及传统室内定位技术的缺陷,设计了一种基于相位差测距的射频识别(RFID)室内定位系统.系统主要由RFID阅读器、电子标签、STM32模块组成,3个电子标签固定在特定位置作为信标节点,1个RFID阅读器作为移动节点发射与接收超高频信号,STM32模块根据测得的相位差计算相应的距离,并利用改进后的三边定位法,确定阅读器的位置.在实验室对进行了设计并测试,结果表明:该系统能很好地完成定位功能,定位精度达到厘米(cm)级,可满足众多领域的应用需求.     

一种基于高频RFID的室内定位方法的设计与实现

根据定向阅读器波瓣图的特征,使用步进电机以恒定的角速度驱动UHF-RFID阅读器进行旋转.阅读器扫描覆盖区域内所有的标签,通过计算每个标签的发现时间和失去标签的到达时间差,计算出标签和阅读器之间的到达角数据,推算出标签以阅读器为中心的直线方程;同时结合阅读器旋转的弧度推算出标签所在圆方程轨迹,估算出阅读器的位置坐标.定位系统中只使用两个定向阅读器和若干标签,降低了定位系统的成本和系统的复杂度,提高了定位的精度和效率.     

自适应树形分组的盲分离射频识别系统防碰撞算法

针对单天线射频识别(RFID)系统中阅读器不能同时识别多个标签造成标签识别率较低的问题,结合多天线技术及基于标签ID号序列的二叉树时隙分组提出了一种自适应树形分组的盲分离RFID系统防碰撞算法.首先根据RFID系统中天线的个数调整阅读器查询码码长并发送查询信号,将符合条件的响应标签分配到相应的时隙中,使每一个时隙中的标签数小于或者等于阅读器的天线数,满足盲源分离(BSS)的多天线系统识别标签的条件,从而达到同时且快速识别多个标签的目的.仿真结果表明,与同样采用多天线技术的基于位隙动态分组的盲分离(BSDBG)算法相比,当天线个数为4~32时,所提算法的标签识别速度提高了20%~69%,标签识别率提高了60%~88%,同时该算法复杂度低,硬件开销小,实现相对简单,有利于推广和使用.     

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.