基于RSSI测距误差修正的改进型DV-distance差分定位算法

DV-distance是一种基于多跳机制的定位算法,其相邻节点间的距离通过RSSI测距技术实际测量得到。为了减少RSSI测距误差对定位精度的影响,首先对RSSI测距误差进行修正,再对已有的信标节点间计算距离误差修正值的方法作进一步改进,提出一种基于RSSI测距误差修正的改进型DV-distance差分定位算法。仿真结果表明,相比已有的定位算法,该改进算法不仅能提高节点的定位精度,还能减少网络通信开销及计算复杂度。     

一种自适应煤矿井下环境的加权质心节点定位算法

为提高煤矿井下无线传感器网络节点定位精度,提出了一种自适应煤矿井下工况环境的加权质心节点定位算法;在信标节点双链式部署结构的基础上,首先利用未知节点周围RSSI信号强度最大的信标节点之间的位置信息和信标节点的平均RSSI值自适应地估计环境参数,再应用无线信号强度衰减模型计算未知节点到信标节点的距离,最后采用加权质心定位算法的平均值确定最终的节点位置坐标;仿真实验结果表明,所提出方法的平均定位误差为0.94m,有效降低了环境因素及RSSI的随机性对定位精度的影响,可用于煤矿井下无线传感器网络节点实时定位系统中。     

基于RSSI测距的DV-Hop算法

由于DV-Hop算法在不均匀网络中节点定位精度不高,以及RSSI算法受环境因素影响较大,将RSSI算法与DV-Hop算法相结合,提出一种利用RSSI测距技术改进DV-Hop的算法-----BRDV-Hop算法.该算法应用RSSI测距技术,定义信标节点的平均跳距误差,并利用信标节点的平均跳距误差对未知节点与信标节点之间的距离进行修正,从而达到减小定位误差的目的.仿真结果表明,与标准的DV-Hop算法相比,在不增加传感器节点硬件的基础上,改进算法能有效降低定位误差.     

基于TDOA改进的矿山井下机车定位方法

为提高矿山井下机车的定位精度,提出了一种基于到达时间差（Time Difference of Arrival,TDOA）改进的矿山井下机车定位方法。采用超声波和无线电传播时间差实现测距,分析了测距技术在井下运用时产生的误差,并对误差进行补偿。为了修正机车定位过程中产生的位移误差,把位移误差化简为机车到节点的距离误差。通过规律性地布置节点和惯性导航技术,计算出位移后机车到节点的距离。使用最小二乘法估计出机车的初始位置坐标,并通过泰勒级数最小二乘法修正坐标实现定位,定位精度可达12 cm。相比于传统的定位算法,该方法增加了定位精度,且在机车不同速度下,保持了较为稳定的定位精度。     

基于RSSI测距的信标节点自校正定位算法

节点定位是无线传感器网络中的重要应用之一.为了有效抑制各种因素对无线传感器节点定位精度的影响,以三边定位算法为基础,提出了一种基于误差校正的定位算法.该算法通过测量信标节点之间的距离,获得信标节点RSSI值测量误差和网络的定位误差,并对误差进行补偿,从而提高整个网络的定位精度.实验结果显示,该算法能明显提高定位精度和稳定性,具有普遍应用意义.     

无线传感器网络分布式的移动节点定位研究

针对WSN野外二维特定应用环境,提出了一种到主信标节点信号强度差定位算法（SSDLB）与运动预测定位算法（MPL）相结合的基于分布式的高覆盖率移动WSN节点定位算法,解决了在定位过程中未知节点在某定位时刻其邻居信标节点的个数小于3个的定位问题,并且避免了传统RSSI定位算法把信号强度值转化成距离再进行定位所带来的计算误差与计算开销,一定程度上提高了节点定位精度和覆盖率。仿真实验表明：此算法在较低的信标节点密度的条件下,能够达到较高的定位精度和定位覆盖率,与传统的RSSI算法相比定位性能有显著的提高。     

无线传感器网络中基于RSSI算法的优化

研究表现煤矿井下巷道狭长、信号多径效应明显、通信条件差,井下无线传感器节点定位对环境敏感,导致节点定位误差较大.基于传统的RSSI算法基础上,提出一种给出衰减校正因子的三边加权质心定位算法.算法通过对RSSI衰减测量值补偿校正,近似接近节点间实际真实值;取任意的三点的校正距离算出未知节点的估计值后,求估计值的加权质心坐标为节点估计坐标.仿真结果表明,在相同的实验环境下,该改进的算法比传统的RSSI算法有更小的定位误差,提高算法对环境的适应性和定位精度,为井下无线传感器网络节点定位提供了依据.     

基于RSSI测距的传感器节点质心定位修正算法

针对传感器网络节点定位精度问题,研究基于RSSI测距的定位算法,提出多信标节点质心定位修正算法,通过该算法计算得到多组未知节点估计坐标,并在此基础上利用质心定位修正算法计算节点坐标修正值;利用仿真实验,证明基于RSSI测距的传感器节点质心定位算法定位精度比传统质心定位算法定位精度提高13.8%,比RSSI加权质心定位算法提高6.3%。     

基于OMNeT++平台的DV-Hop定位算法改进

无线传感器网络中经典定位的DV-Hop算法进行了研究.针对该算法定位误差较大的问题,提出了改进方法:利用RSSI测距来确定与信标节点距离较近的未知节点的位置,将其升级为信标节点,从而增加信标节点的数目,在一定程度上改善因远离信标节点定位误差较大的现象;在计算未知节点坐标时,采用自由搜索的算法代替误差较大的三边测量法.通过OMNET仿真证明:改进后的算法性能稳定,在相同信标节点比例下,算法的定位误差相较于传统的DV-Hop算法减小了13.5％左右.     

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.     

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.     

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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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