基于TDOA的室内运动目标双曲线RFID定位方法

射频定位中以接收信号强度（ RSSI）定位的方法存在信号干扰严重、抖动剧烈和误差较大等现象。为了减小射频信号定位的误差,在基于精准时间测量思想的传播信号到达时间差（ TDOA）方法和构建虚拟参考标签经典定位方法的基础上提出了TDOA双曲线定位方法。该方法利用射频信号TDOA,以精准时间差来测量射频（ RF）标签与目标之间的距离,然后借助双曲线定位算法对目标进行定位。仿真结果表明,相比目前经典的 LANDMARC 和VIRE定位方法,TDOA双曲线算法的定位误差50'可在0.216 m内。该方法有效利用了现代高精度时间测量的优势,在室内运动目标定位中具有定位精度高、应用范围广、实现简单等优点。     

基于信号强度的分组帧时隙ALOHA防碰撞算法

针对现有ALOHA防碰撞算法存在系统吞吐量低下的问题,利用射频识别阅读器和标签之间的信号能量传输特点,对帧时隙ALOHA算法( FSA)进行改进,提出一种分组帧时隙ALOHA防碰撞算法。根据接收信号能量的强度将标签均匀分布到帧时隙中进行分组应答,从而降低标签碰撞概率。仿真实验结果表明,在标签数与帧时隙数之比小于1.8的情况下,该算法最大系统吞吐量可达50%,优于FSA算法及碰撞分组算法。     

基于分层定位模型的RFID定位算法研究

识别和定位为智能停车场等服务领域提供关键信息,基于RFID的LANDMARC算法为常见的室内定位方法。文中对低成本、高精度的经典室内定位算法LANDMARC进行分析,针对其在定位过程中单纯根据信号强度的欧几里得距离选择节点进行定位计算的不足,提出基于双层定位模型的算法D-LANDMRAC。该算法主要由初步定位和精确定位两部分组成,初步定位过滤掉问题参考标签,再基于“距离-损耗冶公式利用标签之间信号强度差进行精确定位。仿真结果表明,相比LANDMARC算法,D-LANDMRAC算法定位精度有了明显的提高,并且定位误差的分布更加均衡。     

区域细化的RFID室内定位算法

提出一种在LANDMARC算法基础上进行定位区域细化的RFID室内定位算法(RDL)。首先对低成本、高精度的LAND-MARC算法进行简单分析,针对其计算中涉及过多无关参考标签和读卡器问题引入区域细化策略。算法利用对射频信号强度调制进行定位区域的细化,消除距离待定位标签较远的读卡器和参考标签对定位计算的影响。仿真结果表明,相比LANDMARC算法,该算法定位精度更高,定位误差的概率分布也更为合理。     

面向车间布局的自适应LANDMARC算法

在车间定位中,运用基于有源射频识别校验的动态定位(LANDMARC)算法时,由于车间障碍物引起的多径效应和边界处参考标签数量不足,算法无法正确选择参考标签中的最近邻,对此,提出一种面向车间布局的自适应LANDMARC算法。首先引入对数距离路径损耗模型处理RFID读写器接收信号强度指示(RSSI),再通过对比法筛选出参考标签有效值以及插值法在边界插入虚拟标签。对比传统LANDMARC算法,将定位平均误差从0.39 m降低到0.16 m,证明了自适应LANDMARC算法的有效性。     

监狱犯人室内定位算法研究

室内定位技术因其在搜索、救援和安全方面的良好使用价值,越来越受到人们的关注。本文主要对基于室内监狱犯人的RFID室内定位算法进行研究,主要涉及其工作原理和相关的定位算法,特别是对LANDMARC室内定位算法进行了深入的研究以及改进优化,根据LANDMARC算法的缺点,通过对LANDMARC算法中阅读器的位置分布,参考标签的分布密度以及选取的参考标签数k值的优化改进,得出更优的LANDMARC改进算法,获得更好的定位精度和定位性能。改进的算法通过Matlab7.0模拟,提高监狱犯人室内定位精度,确保监狱的安全,提高效率。     

引入RSSI指纹抖动量的室内定位改进算法

为提高接收信号强度指示( RSSI)指纹进行室内定位的准确性,提出一种利用RSSI指纹抖动量的虚拟标签定位改进算法。给出RSSI指纹抖动量计算方法,将其应用于待定位标签与参考标签的距离以及虚拟标签RSSI指纹的计算。在实际测试中,将RSSI指纹抖动量用于虚拟标签定位算法射频指纹( RFFP)的改进。测试结果表明,与 RFFP 算法和 LANDMARC 算法相比,改进算法的平均定位精度分别提高约0.35 m ~0.88 m 和0.38 m~0.94 m,算法耗时仅分别增加约1%和12%。     

煤矿巷道多源数据融合定位算法研究

煤矿巷道非视距条件下单独使用飞行时间定位算法或接收信号强度算法存在方向判断不准确、定位误差较大等问题;飞行时间定位算法与接收信号强度算法联合定位,虽然在方向判断的准确率上较单独的飞行时间定位算法有所提高,但对于标签在非视距运动场景下的判断仍不够准确,定位轨迹不够平滑。针对上述问题,提出了一种基于飞行时间定位算法、接收信号强度及多项式插值方法的煤矿巷道多源数据融合定位算法。该算法首先测量标签与定位基站间的飞行时间,并计算接收信号强度,然后根据标签历史轨迹采用多项式插值方法拟合、预测当前时刻标签位置,根据预测位置、飞行时间和接收信号强度组合判定标签相对基站所在方向,最后通过加权数据融合优化定位结果,从而提高定位稳定性及准确度。实验结果表明,相比于单一飞行时间定位算法或接收信号强度算法,该算法有效提高了定位系统的精度和稳定性,可以更准确地判断标签相对基站的方向,方向判断准确率高达99%。     

一种利用历史数据构造虚拟标签的定位算法

在RFID定位算法中,利用接收信号强度统计模型进行直接定位的精确度不高,而利用实际参考标签定位存在信号易碰撞、外出部署不便等问题,因此提出一种基于虚拟标签的RFID定位算法VIREH以克服以上缺点.该算法利用历史数据构建虚拟参考标签,然后利用虚拟参考标签代替实际参考标签进行定位.依据VIREH算法,开发基于Android移动设备的RFID定位系统,在系统中使用VIREH算法进行定位,对定位误差进行了统计以测试算法性能.测试结果表明,VIREH算法的定位精度较直接定位有显著提高,较使用实际参考标签没有明显降低,有助于提高RFID定位精度.     

基于动态预约机制的防碰撞算法

针对无线射频识别系统中标签预约防碰撞算法不能有效利用预约时隙的问题,提出一种新的防碰撞算法。将每一轮的标签识别过程分为标签预约和标签读取2个阶段。在标签预约阶段,待识别标签随机选择一个预约时隙发送标签序列号的前一部分,即传统标签预约算法发送固定长度的短随机序列,每一轮预约时隙的数量根据估计的标签数量动态调整。在标签读取阶段,读写器根据预约时隙状态,通知选择可读预约时隙的标签继续发送序列号的剩余部分。实验结果表明,该算法采用动态预约机制,降低了冗余信息的发送量,可以有效减少碰撞和空闲时隙数。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

正~~