基于移动锚节点的加权质心定位算法研究

针对加权质心定位(WSL)算法所需锚节点数目较多,定位精度低,定位成本高等问题,采用单个移动锚节点沿着既定的轨迹在监测区域移动,并在规定位置广播数据包;未知节点根据接收的信号强度(RSSI)比值以及邻居节点间的最小跳数确定权值,进而估算未知节点自身的坐标位置.仿真结果表明:算法有效地提高了定位精度和稳定性,降低了定位成本.     

一种基于坐标改正的改进DV-Hop定位算法

为有效提高DV-Hop算法在拓扑随机网络中的定位精度,提出一种利用锚节点定位误差修正未知节点坐标的新方法(PEDV-Hop).首先定义伪距误差因子剔除对平均跳距计算产生较大误差的锚节点,从而有效抑制网络拓扑随机分布影响,提高平均跳距计算精度;其次,视锚节点为未知节点,在计算平均跳距的同时,运用三边或多边测量法评估自身定位坐标,从而可计算得到锚节点坐标改正值,并将平均跳距与坐标改正值向网络广播;最后,未知节点根据接收到各锚节点的坐标改正值来修正自身定位误差,从而有效提高节点定位精度.仿真结果表明,PEDV-Hop算法实现简单,有效提高了节点的定位精度.     

基于移动锚节点的WSN节点定位方法

为提高WSN定位精度,提出一种带定向天线的移动锚节点定位算法。首先对WSN进行分层,锚节点可沿x轴和分层线移动实现对未知节点的遍历,在移动过程中等间隔距离旋转定向广播位置信息,未知节点根据接收到的锚节点坐标、方位角等信息确定自身位置。定位算法简单,无需测距,完全使用锚节点信息实现定位,仿真结果表明,该算法比典型的采用单个移动锚节点的SLWL算法具有更高的定位精度和定位稳定性。     

基于虚拟力移动锚节点的3D-DVHop-ACR定位算法

针对传统以及各种经改进的3D-DVHop算法对未知节点定位误差较大,且未对定位成本进行实质性降低的问题,提出一种基于虚拟力移动锚节点的3D-DVHop-ACR定位算法.该算法引入虚拟力移动锚节点,在降低定位成本的同时可使锚节点移动路径遍历整个网络空间且不会进入网络空洞区域;通过RSSI值辅助测距与三维跳距加权修正节点间跳数和跳距,利用所有锚节点定位误差修正各未知节点估计坐标;同时,结合最大似然估计法对邻居节点数不小于3的节点继续精化,以进一步降低定位误差.     

基于误差加权的三维双曲线定位算法

为了减小三维空间中对未知节点定位的误差,提高三维DV-Hop算法的定位精度,提出一种基于误差加权和三维双曲线定位的三维DV-Hop改进算法.改进算法首先采用误差加权的方法处理未知节点的平均每跳距离,然后分类选择未知节点与锚节点之间的跳段距离,最后将二维双曲线法扩展到三维空间计算未知节点的坐标.仿真实验结果表明,改进算法在三维WSN环境中可以对未知节点进行有效的定位,平均定位误差和定位精度显著优于三维DV-Hop算法,相较于对比文献也有一定的提升,并且锚节点密度和通信半径对平均定位误差和定位精度的影响较小.     

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。     

移动无线物联网感知层传感节点定位算法研究

为了解决当前算法在锚节点密度较低时,传感节点定位精度不高的问题,提出了移动无线物联网感知层传感节点定位算法。建立了包含锚节点误差的移动无线物联网模型;根据共线度筛选候选锚节点。加权平均处理锚节点可信度,计算每个未知传感节点的平均跳距和未知传感节点定位误差,将计算误差低于设定阈值的未知传感节点转化为锚节点,并对初步定位结果进行循环位置修正,实现感知层传感节点定位。仿真结果表明,所提算法在锚节点密度相同时的定位误差低于2.5。     

基于RSSI校正的无线传感器网络定位算法

为了使接收信号强度指示（RSSI）的测量误差对节点定位精度的影响程度达到最小化,提出一种基于RSSI高斯加权校正的质心定位算法.首先通过高斯函数滤去偏差较大的RSSI值,然后再对余下的RSSI值加权计算得到优化的RSSI测量值,并利用测量到的RSSI值计算出锚节点与未知节点之间的距离,然后根据计算出的距离对锚节点坐标加权,并通过质心定位算法求出未知节点的位置坐标.仿真实验表明：该算法相比基于RSSI的质心定位算法,定位覆盖率提升3％～6％,平均定位误差至少减少4％,是一种定位精度更高的算法.     

基于组合测距的无线传感器网络自定位算法

针对如何在锚节点密度较低的情况下提高无线传感器网络中节点自定位精度的问题,本文提出了一种基于RSSI和TDOA组合测距的加权质心定位算法.该算法分别对传统RSSI和TDOA测距模型增加了校验参数及温度补偿,将未知节点与锚节点间距离估计值的倒数作为权值参数,再利用加权质心算法计算出未知节点的位置坐标.硬件试验表明室内环境中基于改进RSSI测距模型的定位算法相比于传统RSSI质心定位算法的误差改进比率为56.2%,仿真结果显示基于组合测距的定位算法在锚节点密度较低时也能达到较高的定位精度.     

一种单移动锚节点的无线传感器网络定位算法

研究了无线传感器网络的节点定位算法,提出了一种利用一个移动锚节点来实现定位的新算法。该算法利用一个移动锚节点,按照规划好的路径遍历整个网络,当移动锚节点移动到未知节点的通信半径以内,未知节点就可以接收锚节点的位置信息。当未知节点接收到三个以上的处于其通信半径上的位置信息,就可以计算出未知节点的坐标。最后,通过仿真研究了该算法的特性,仿真结果表明该定位方法在定位误差、能耗等方面均表现出良好的性能。     

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.     

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.     

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.     

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)

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