一种新的概率逼近遍历算法在雷达布站的应用

针对基于测量到达时间差（TDOA）跟踪定位目标的无源雷达布站优化问题,根据TDOA定位原理,综合考虑目标空域、站址误差和时差测量误差,推导出衡量目标跟踪定位精度的几何精度因子（GDOP）计算公式,并将网格化后的GDOP加权均值作为评价函数。按照均匀概率随机产生站址组合样本,根据站址数量确定样本规模,遍历样本获得评价函数最小的站址组合。经过超算实际运行算例测试,最优雷达布站站址组合寻优成功率达到99.99995%,目标跟踪定位精度优于3 km。     

相机一维标定的最优加权线性算法

为了进一步提高相机一维标定线性算法的精度,提出一种最优加权线性算法.首先对相对深度的约束方程进行一次最优加权得到其新的估计量,并指出一次最优加权具有与迭代最优加权相当的精度以及更少的计算量;然后对绝对二次曲线的像的约束方程也进行一次最优加权,并通过对最优权进行适当的近似以进一步减少计算量.实验结果表明,该算法的标定精度比现有的加权线性算法的精度更高,与光束法平差算法的精度相当.     

基于概率密度的多基阵声目标被动定位算法研究

采用一种基于概率密度的方法对常规多站时差定位法进行改进,并给出该方法的计算推导公式.该算法在获取目标位置初始值的基础上,将目标方位看成是满足一定概率密度的多个测量子集,寻找出多个子集共同密度对应的最大点,即为目标的最终位置.通过实测数据验证,实验结果表明,在合理布置辅阵位置的基础上,基于概率密度的定位算法可以大幅度降低定位误差,从而提高定位精度.尤其是在目标远距离飞行时,定位精度明显优于常规时差定位法,具有重要的实用价值.     

时延估计算法在乒乓球落点检测中的仿真研究

到达时间差(TDOA)是一种重要的信号发射源定位方法,它通过处理多个信号发射传感器采集到的信号到达时间测量数据来实现声发射源目标的定位,具有较高的定位精度。运用四种不同加权函数的广义互相关时延估计方法,来提高乒乓球辅助评价系统中关于乒乓球落点位置的精度。对广义互相关法的四种不同的加权函数进行介绍和阐述,将噪声信号加入原信号,使用Matlab进行实验仿真。实验结果表明:使用PHAT加权和SCOT加权可以提高时延估计的精度,从而达到更精准的估计出乒乓球落点位置的目的。     

高速弹丸轨迹精度影响因素研究

高速弹丸轨迹动力学建模结果的精度依赖于从测量数据中合理选择初值，但当前对初值的选取没有明确标准，无法保证得到高精度的建模结果。研究了测量轨迹全程的误差分布，为合理的初值选取提供了基本依据。基于误差传递理论对高速弹丸的雷达测量结果进行精度估计，采用零攻角三自由度模型进行弹道轨迹建模，确定对建模结果有影响的6个精度参数，并进行仿真计算，分析雷达测元误差和弹丸相对雷达的运动情况对测量轨迹精度的影响。整体而言，弹道轨迹精度与目标和雷达测站的相对关系及目标弹道特点有很强的相关关系。雷达测元误差对速度精度影响不大，位置精度的变化与测元变化趋势明显相关，x和z方向的误差逐步变小，而y方向的误差在末段明显增大。本研究结果有助于合理选择最优初值点，进而有助于提高建模结果精度。     

非视距环境中的无线网络残差加权定位算法

无线定位已成为物联网应用的重要研究内容,为减小非视距(NLOS)误差对传统定位算法的精度的影响。因此提出一种基于目标临时位置估计的残差幂次方加权定位算法。算法核心在于先利用分组定位得到不同目标节点估计位置,并将位置之间的差值定义为临时定位残差。然后区别于传统残差加权定位算法,本文提出用残差的高次幂作为加权函数,并通过仿真搜索最优的加权函数。仿真结果表明,当LOS-SN数目不小于2时,本文算法在定位精度上远高于传统的NLOS抑制定位算法。和传统的残差加权定位算法(RWGH)相比,本文所提算法的定位精度提高了近60%,同时降低了对LOS-SN个数的要求。和半正定规划(SDP)相比,定位精度提高了近38%,并降低了计算复杂度。     

基于数据压缩的雷达网络定位研究

针对双基地雷达空间定位系统在发射站附近区域的定位性能较差,存在基线盲区的问题,为提高定位精度,提出了特定的三基地雷达空间定位数据压缩算法.将多个雷达测量组合表示的目标位置压缩冗余,利用非线性坐标方程在目标的真实坐标附近展开为泰勒级数,并采用加权最小二乘法对冗余数据进行压缩合并,充分利用各雷达站的定位信息,进行仿真.仿真结果表明直线布站定位性能略优于均匀布站,三基地定位性能明显优于双基地定位性能,改善了发射站附近区域的定位性能,解决了双基地雷达空间定位的基线肓区问题.算法明显提高了目标定位精度,具有一定的有效性和实用性.     

坐标转换在雷达组网中的应用

雷达组网需要进行坐标转换的计算,其前提需要知道各个雷达之间的相互位置,所以首先要测量雷达之间的相对坐标.本文介绍了在雷达组网中可采用的测量雷达间相对坐标的几种方法,并分析了这些测量方法适应的条件,测量精度.根据测量的简易程度、适应范围以及测量精度讨论了各自的优缺点.     

基于最优探测的多机器人路径规划

目前,针对多机器人目标探测定位系统,机器人通常获取相对于目标的角度信息,然后进行融合实现定位目标。采用此种定位算法,机器人相对目标的距离越近、相邻机器人与目标之间的夹角越均匀,目标的定位精度越高。然而由于目标与机器人分布的随机性,在定位的过程中,通常无法同时保证机器人相对目标距离最近、夹角最优。那么如何实现多机器在探测目标过程中,每个时刻机器人对目标的定位精度最优?提出了多机器人最优探测路径规划算法。每个机器人在单位时间内按直线移动,那么机器人下一时刻的位置轨迹,即以当前位置为圆心的圆。根据机器人定位的精度模型标准,采用内点优化算法求解得到圆上的一点,使得精度模型标准取得最优值,即定位精度精度最高,这点即为下一时刻机器人的位置。由此不断求得机器人下一时刻的位置,即可获得机器人移动的路径。仿真结果表明,算法能够实现在多机器人探测定位目标过程中,协同路径规划保证每个时刻目标定位精度最优。     

全源矿井定位:一种智能煤矿位置服务新范式

矿山动目标定位系统为煤矿智能化建设提供基于位置的服务。而传统的矿井定位系统中定位信标与定位标签之间大多采用单一或组合通信技术,结构不灵活,覆盖范围受限,鲁棒性不高,定位精度有限;使用单一或组合测距技术,无法根据使用场景的不同自适应选择最优测距技术;位置求解算法固定,无法根据使用场景的不同和信号变化自适应选择最优求解算法。提出了全源矿井定位新范式,可根据定位环境和目标承载平台的变化,从所有可用定位信号测量设备中动态选择满足当前需求的最优设备组合,自适应地从可用的测距算法、位置解算算法、结果优化算法中选择最优的算法组合,计算出目标节点的最优位置。给出了全源矿井定位系统架构,探讨了矿井中可用的定位信号测量设备和可用于定位的测量属性值类型,对比了单一矿井定位与全源矿井定位在定位服务器方面的功能差异。研究了全源矿井定位中的3项关键技术:统一定位框架技术,旨在解决全源定位的模块化、组合式、可扩充需求;全源定位信息融合技术,对测量属性值进行有机组织,达到提高定位精度的目的;通信定位一体化技术,通过无线通信网络本身所具有的定位能力,简化全源矿井定位系统的设计并提高定位精度。提出了基于“端-边-云”的全源矿井定位系统实施架构,以便与煤矿智能化的主流建设模式相适应,大幅降低实施难度和系统成本。     

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)

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