Multi-Branch Fault Line Location Method Based on Time Difference Matrix Fitting

The distribution network exhibits complex structural characteristics,which makes fault localization a challenging task.Especially when a branch of the multi-branch distribution network fails,the traditional multi-branch fault location algorithm makes it difficult to meet the demands of high-precision fault localization in the multi-branch distribution network system.In this paper,the multi-branch mainline is decomposed into single branch lines,transforming the complex multi-branch fault location problem into a double-ended fault location problem.Based on the different transmission characteristics of the fault-traveling wave in fault lines and non-fault lines,the endpoint reference time difference matrix S and the fault time difference matrix G were established.The time variation rule of the fault-traveling wave arriving at each endpoint before and after a fault was comprehensively utilized.To realize the fault segment location,the least square method was introduced.It was used to find the first-order fitting relation that satisfies the matching relationship between the corresponding row vector and the first-order function in the two matrices,to realize the fault segment location.Then,the time difference matrix is used to determine the traveling wave velocity,which,combined with the double-ended traveling wave location,enables accurate fault location.

GPS非差精密解算软件PLAOD及其性能分析

PLAOD(precise location and orbit determination)是西南交通大学自主研发的GPS非差精密定位定轨软件.该软件目前能够处理GPS观测数据,具有高精度定位、大气反演和低轨卫星轨道确定功能.本文在介绍PLAOD相关理论的基础之上对其性能进行了分析.利用多组GPS观测数据进行测试,通过与IGS(international GNSS service)等相关机构精密产品对比,PLAOD具备如下性能:静态定位精度可达毫米级;动态定位精度可达厘米级;静态对流层天顶延迟的估计精度通常优于1 cm,动态对流层天顶延迟的估计精度在2 cm以内;电离层天顶延迟估计结果与IGS的IONEX(ionosphere exchange)产品具有较高的吻合度;与JPL(jet propulsion laboratory)提供的简化动力学低轨卫星轨道相比,几何法确定轨道的准确度可达厘米级.

Information Method for Synthesis of Optimal Data Subsystems Designated for Positioning, Location and Remote Sensing Systems

The general classification of information systems of remote action, including such system as positioning systems, location systems and remote sensing systems is suggested. In view of formulated limitation conditions the common mathematical information model of data transfer subsystems of considered systems is suggested. The optimization of developed information model is carried out and the optimal operation regimes of these data transfer subsystems are

Tunnel personnel positioning method based on TOA and modified location-fingerprint positioning

To position personnel in mines, the study discussed in this paper built on the tunnel personnel positioning method on the basis of both TOA and location-finger print(LFP) positioning. Given non-line of sight(NLOS) time delay in signal transmission caused by facilities and equipment shielding in tunnels and TOA measurement errors in both LFP database data and real-time data, this paper puts forth a database data de-noising algorithm based on distance threshold limitation and modified mean filtering(MMF), as well as a real-time data suppression algorithm based on speed threshold limitation and MMF.On this basis, a nearest neighboring data matching algorithm based on historical location and the speed threshold limitation is used to estimate personnel location and realize accurate personnel positioning.The results from both simulation and the experiment suggest that: compared with the basic LFP positioning method and the method that only suppresses real-time data error, the tunnel personnel positioning methods based on TOA and modified LFP positioning permits effectively eliminating error in TOA measurement, making the measured data close to the true positional data, and dropping the positioning error:the maximal positioning error in measurements from experiment drops by 9 and 3 m, respectively, and the positioning accuracy of 3 m is achievable in the condition used in the experiment.

A User Proprietary Obfuscate System for Positions Sharing in Location-Aware Social Networks

A user’s trajectory can be maliciously monitored by adversaries when they share the positions in location-aware social networking applications which require users to update their own locations continuously. An adversary infers user’s locations from the trajectories, and gleans user’s private information through them via location-aware social networking applications and public available geographic data. In this paper, we propose a user proprietary obfuscate system to suit situations for position sharing and location privacy preserving in location-aware social network. Users transform the public available geographic data into personal obfuscate region maps with pre-defined profile to prevent the location leaking in stationary status. Our obfuscation with size restricted regions method tunes user’s transformed locations fitting into natural movement and prevents unreasonable snapshot locations been recorded in the trajectory.

Using self-location to calibrate the errors of observer positions for source localization

The uncertainty of observers＇ positions can lead to significantly degrading in source localization accuracy. This pa-per proposes a method of using self-location for calibrating the positions of observer stations in source localization to reduce the errors of the observer positions and improve the accuracy of the source localization. The relative distance measurements of the two coordinative observers are used for the linear minimum mean square error （LMMSE） estimator. The results of computer si-mulations prove the feasibility and effectiveness of the proposed method. With the general estimation errors of observers＇ positions, the MSE of the source localization with self-location calibration, which is significantly lower than that without self-location calibra-tion, is approximating to the Cramer-Rao lower bound （CRLB）.

LOCATION OF DOUBLE BOND POSITION OF INSECT SEX PHEROMONE BY GC/MS ANALYSIS WITH CHEMICAL IONIZATION

Ozonolysis products of four lepidopteral pheromone were identified by methane CI-MS.The spectra obtained were notably simpler than those of EI-MS,the peak of molecular ion was normally close to the base peak,and the characteristic fragment ions were high in m/z,thereby the interpretation was facilitated.

Offline handover location positioning for map matching of mobile probes

Handover location technology was employed for collecting road traffic information in a number of field projects,and the project results demonstrate that it is a supplementary and promising means of road traffic information collection for further traffic supervision and maintenance.Because handover location technology is one kind of pattern matching based location technologies,offline handover location positioning is an essential problem to be studied for successfully matching mobile probes on GIS map.Offline handover location positioning method involves two stages,handover location positioning respectively via two weighted models and an optimized model based on the intermediate results obtained in the first stage.A preliminary field test is conducted on a stretch of freeway in the inner suburban region in Beijing,and performance evaluation results show that the proposed method is superior to standard least square model in location accuracy and location precision,which is an effective method of offline handover location positioning.

A COLLABORATIVE LOCATION MODEL FOR CELLULAR MOBILE POSITION LOCATION

In cellular network, several Time Difference Of Arrival (TDOA) location algorithms can be applied to mobile position estimation. However, each algorithm has its own limitations and none of them is proved to be the most reliable one in different channel environments. In this paper Kleine-Ostmann's data fusion model is modified and a collaborative location model which incorporates position estimate of two TDOA location algorithms is proposed.Analysis and simulation show that more reliable and accurate mobile position estimation can be achieved based on this model.

Research Status and Trends of Indoor Positioning and Navigation Technology in China

As an essential component of future comprehensive Positioning,Navigation,and Timing(PNT)system,indoor positioning technology has extensive application demands,making it a focal point of attention in both academia and industry.This article comprehensively reviews the research status of indoor positioning technology in China,with a focus on highlighting representative achievements and application validations from major research institutions in recent years.It addresses the challenges and issues faced in promotion and application of large-scale,high-precision indoor positioning.Furthermore,a universal and seamless indoor-outdoor positioning system architecture is proposed,along with a technical roadmap and key technologies to achieve this architecture.Finally,an analysis and outlook on future technological trends are presented.

Performance Evaluation of Three-Dimensional UWB Real-Time Locating Auto-Positioning System for Fire Rescue

Fire rescue challenges and solutions have evolved from straightfor-ward plane rescue to encompass 3D space due to the rise of high-rise city buildings.Hence,this study facilitates a system with quick and simplified on-site launching and generates real-time location data,enabling fire rescuers to arrive at the intended spot faster and correctly for effective and precise rescue.Auto-positioning with step-by-step instructions is proposed when launching the locating system,while no extra measuring instrument like Total Station(TS)is needed.Real-time location tracking is provided via a 3D space real-time locating system(RTLS)constructed using Ultra-wide Bandwidth technology(UWB),which requires electromagnetic waves to pass through concrete walls.A hybrid weighted least squares with a time difference of arrival(WLS/TDOA)positioning method is proposed to address real path-tracking issues in 3D space and to meet RTLS requirements for quick computing in real-world applications.The 3D WLS/TDOA algorithm is theoretically constructed with the Cramer-Rao lower bound(CRLB).The computing complexity is reduced to the lower bound for embedded hardware to directly compute the time differential of the arriving signals using the time-to-digital converter(TDC).The results of the experiments show that the errors are controlled when the positioning algorithm is applied in various complicated situations to fulfill the requirements of engineering applications.The statistical analysis of the data reveals that the proposed UWB RTLS auto-positioning system can track target tags with an accuracy of 0.20 m.

基于自适应距离ADWKNN室内定位算法

针对基于蓝牙接收信号强度(RSS)的加权K-近邻(WKNN)位置指纹室内定位算法中由于信号波动存在的单一距离估算标准导致定位精度偏低的问题,提出了一种基于自适应距离的ADWKNN定位算法。离线阶段利用K-means聚类算法对指纹数据库进行划分,减少数据查询量以保证定位的时效性。在线定位阶段首先对待定位点处采集到的RSS信号值进行卡尔曼滤波,减弱随机噪声的干扰;然后采用ADWKNN算法计算曼哈顿距离与欧氏距离的标准差,自适应的选择距离估算方法并实现K值的动态变化。实验结果表明,ADWKNN算法的平均定位精度为1.22 m,与使用余弦距离、曼哈顿距离、欧氏距离和Sorensen距离的单一距离的WKNN算法相比,ADWKNN算法的平均定位精度有明显提高。

时差定位系统对雷达猝发的定位性能分析

针对雷达暴露时间长,容易被无源定位系统截获和定位的问题,研究了雷达猝发对降低到达时间差(Time Difference of Arrival, TDOA)无源定位系统定位精度的影响。首先,介绍了雷达猝发和TDOA无源定位系统定位原理。然后,建立了雷达猝发对TDOA无源定位系统的影响模型,推导了雷达猝发下的克拉美-罗下界(Cramer-Rao Lower Bound, CRLB)。仿真实验表明,雷达的猝发模式可以有效降低TDOA无源定位系统的定位精度,延长定位时间。当雷达辐射时间为0.5 s,雷达辐射间隔为1 s时,与连续辐射方式相比,定位精度降低了0.26%·R(R为探测距离),定位时间延长了2.5 s。

基于模型识别的有源配电网单相接地故障定位方法

分布式电源(distributed generation,DG)大量接入使配电网继电保护面临严峻挑战。单相接地故障发生概率大,但故障信息十分微弱,特别是在DG多样化故障输出特性的影响下,有源配电网单相故障定位的准确性常难以保证。为此,提出了一种基于模型识别的有源配电网单相接地故障定位方法。分析了配电网单相接地故障下DG的输出特性,建立了在不同故障位置下有源配电网的正序增广网络,构建了故障位置关于馈线出口以及DG输出电流的函数,建立了配电网单相接地故障位置模型,利用不同故障位置下短路电流矢量占比系数的差异性构建了新的故障定位判据。通过将单相接地故障定位问题转化为故障位置模型系数的求解问题,提高了故障定位的准确性和实用性。理论和仿真分析表明,在不同故障位置、不同过渡电阻下均能准确定位单相接地故障,具有原理清晰、故障特征量采集便捷、灵敏性和可靠性高的优点。

心内心电图定位技术在PlCC导管头端定位的应用

目的探讨心内心电图定位技术在PICC导管头端定位的临床应用效果。方法选取我科2013年10月~2014年12月收治的115例置入PICC患者作为研究对象,所有患者均按统一的程序完成置管,并在置管过程中运用心内心电图定位技术对PICC导管头端定位,置管后再次行X线拍片定位。结果心内心电图对PICC头端进入上腔静脉的灵敏度为93.03%,108例患者出现特征性P波,7例无P波变化;X线片显示108例导管头端位于上腔静脉内,2例在锁骨下静脉内（2例静脉走向打圈,导致导管在静脉内打圈长度不足,未到达上腔静脉）,2例在颈静脉内,3例在肱静脉内。结论对PICC导管头端定位采取心内心电图定位技术,具有较高的灵敏度与特异度,可临床推广应用。

非合作线谱声源分布式定位方法

非合作目标定位是水声定位领域的研究热点。为充分挖掘并利用各类可观测参数,提高非合作目标定位能力,提出一种基于目标频率变化信息的非合作目标定位方法。该方法针对匀速直线运动目标的定位问题,首先根据多普勒频移原理,建立观测频率与目标辐射频率、目标运动速度、位置之间的函数映射关系,利用最小均方准则建立目标函数,通过优化算法估计分布式定位系统中各个测量单元与目标运动轨迹的致近点距离,最后综合各观测节点的测距结果,构建几何定位模型,求得目标运动轨迹的解析解。通过仿真分析,证明了该方法的有效性,并指出了该方法需要目标通过与各测量单元的致近点才能获得较好的距离估计能力。文中分析了不同频率估计精度对定位精度的影响,结果表明,提出的定位方法对测频精度具有一定的容限,是一种高精度的非合作线谱声源定位方法。

基于RSSI的修正补偿三边定位算法设计与仿真

在无线传感器网络节点定位过程中,三边定位算法常结合测距算法获取未知节点的位置信息。针对现有三边定位算法定位精度低、适用范围小和需要多次发送定位数据包导致节点能耗增大等问题,提出一种修正补偿测量距离的三边定位算法。相比常见发送多次定位数据包然后进行滤波计算降低定位误差的方法,采用对数常态-模型测量节点间距离,发送较少定位数据包,通过判断三锚节点圆的相对位置,对由于测距误差较大导致节点圆不相交的3种情况进行修正补偿,采用基于质心算法的三边定位算法计算未知节点坐标。通过搭建Matlab仿真试验,验证算法可行性及定位精度,试验结果表明,提出的修正补偿三边定位算法综合考虑了定位精度、算法复杂度和节点功耗3者之间的关系,适用范围更广,定位误差<15%。

光轴位置测量数据辅助立体影像无控定位技术

在卫星摄影测量中,相机参数经过在轨标定后,仍有随时间变化的低频误差,在无地面控制点情况下,这类低频误差影响卫星影像的定位精度。基于光学自准直原理的光轴位置测量设备可以在轨实时监测相机参数的变化情况,对于全球实时或准实时影像处理,可以使用该测量数据削弱低频误差对立体影像定位精度的影响。本文基于光轴位置测量设备的工作原理,建立了光轴位置测量数据辅助立体影像定位的模型和算法,并利用高分十四号卫星数据进行了试验验证。试验结果表明,利用光轴位置测量数据辅助立体影像定位,无须频繁地进行相机参数在轨标定,也无须地面控制点支持,即可实现卫星影像高精度定位,且全球范围内影像无地面控制点定位精度基本一致,平面精度约为1.87 m,高程精度约为0.73 m。

适用于严苛正序助增系数计算的故障位置快速选取方法

针对相间距离保护整定计算中严苛正序助增系数对应故障位置的选取效率较低及精度不足的问题,提出适用于严苛正序助增系数计算的故障位置快速选取方法。首先,基于节点阻抗矩阵及矩阵元素的修改公式,推导了正序助增系数表达式,整理得到13类正序助增系数随故障位置移动的可能变化趋势。然后,通过研究正序助增系数随故障位置移动的变化规律,得到5条严苛正序助增系数对应故障位置的选取判据,提出一种适用于各类复杂网络结构的故障位置快速选取方法。最后,通过IEEE多节点标准测试系统验证了所提方法的有效性。故障位置选取精度高于规程选取方法,选取效率高于多点选取方法。

国家地震烈度速报江苏子系统参数测定能力评估

分析了2023年3月以来江苏地震烈度速报与预警系统震源参数测定的可靠性和精度。研究选取2022年3月1日至2023年12月20日期间江苏地区发生的98条M_(L)≥2.0地震事件,对比了新旧两套系统对同一事件的定位结果。结果显示,震中位置偏差大多数在0.3~12.1 km范围内,大部分误差属于正常范围。两套系统的震级偏差普遍较小,只有少数结果因定位台站的数量、钟差、数据噪声和干扰等因素导致偏差较大。此外,监测能力方面,新系统的监测能力整体提升M_(L)0.5,二维模拟地震定位测试方法显示定位精度也有所提升,整体来看,新系统展现出良好的实效性,能为地震分析和科学研究提供可靠的数据支持。