基于CFR虚拟阵列天线的AOA室内定位

准确地估计信号的到达角（Angle Of Arrival,AOA）为实现在室内高精度定位提供了可能,为了能够准确地估计室内多径信号的AOA,并提取出直射路径的AOA信息进行定位,本文提出一种利用信道频率响应信息（Channel Frequency Response,CFR）扩展阵列天线的亚米级室内定位系统.首先,采集CFR信息进行AOA和信号到达时间（Time Of Arrival,TOA）的联合估计;其次,提出了一种基于AOA和TOA二维聚类信息的直射路径识别算法;另外,还提出了可视环境（Line Of Sight,LOS）以及非可视环境（Non Line Of Sight,NLOS）的识别算法,可以准确的判断出当前接收机相对发射机是处于LOS还是NLOS环境;最后,利用现有的三天线Wi-Fi设备在室内进行了测角以及定位测试,实验结果表明本文提出的定位系统在室内LOS和NLOS环境下分别可以达到中值误差为0.8m,1.3m的定位精度,可用于室内高精度定位.     

基于分布式光纤测温的水管泄漏检测与定位

利用基于拉曼散射和光时域反射技术相结合的分布式光纤测温系统,对自来水管道进行泄漏检测和定位实验研究。分析了系统的温度分辨率和水管道泄漏时泄漏点处的温差情况。选取长200 m和700 m的传感光纤对水管道进行泄漏定位实验,并对检测信号进行小波变换分析处理,最后统计对比了检测系统的漏警率。实验结果表明,该系统运行稳定且能够准确识别管道泄漏情况并进行泄漏定位,定位误差≤1 m。     

TOA/RSS混合信息室内可见光定位方法

为提高室内定位精度,提出一种基于混合到达时间/接收信号强度(TOA/RSS)信息的定位方法。针对室内可见光定位中存在的多径效应造成的定位非线性误差,引入前置无迹卡尔曼滤波的粒子滤波算法,将TOA信息与RSS信息相融合,达到修正非线性误差的目的。然后综合考虑接收端惯性传感参数,对接收端进行运动分析,提升估算坐标的精度。在长宽均为5 m、高度为3 m的室内进行定位仿真,在12 W发光二极管(LED)发射功率下,所提方法获得了平均定位误差为2.02 cm的定位精度。仿真结果证明,所提定位方法的定位性能总体优于指纹定位方法和三边定位的RSS定位方法,具有较强的鲁棒性和较低的定位延迟。     

基于NGST和MODWT的联合初至波到时提取算法

针对传统小波变换模极大值法提取初至波到时存在误判率高、提取精度低的问题,提出了一种基于NGST和MODWT联合提取初至波到时的算法。该方法通过极大重叠离散小波变换解决了塔式算法中因下采样引起的选择起点的灵敏性问题,采用广义S变换现在瞬时极化窗。试验结果表明,与小波变换模极大值相比,基于NGST和MODWT的联合提取初至波到时的算法,误判率低、提取精度高,在地下震源定位、微震监测领域将具有良好的应用价值。     

利用子波变换检测瞬时信号

本文提出一种基于子波变换的检测瞬时信号的方法。推导出一种适合于检测瞬时信号的子波基函数，并将其应用于检测波形和到达时间未知的瞬时信号，利用子波的伸缩和时移特性，通过对信号做多尺度的子波变换，可以在低信噪比下很好地检测到信号，本文还推导了相应的检测统计量及其统计分布特性，理论分析和计算机模拟结果表明，本方法是有效的，是提高检测性能的一种新途径。     

深海直达声区水下声源距离深度联合估计

深海直达声区声场存在明显的多途结构,可用于水下声源被动定位。本文根据一次南海实验获取的数据,研究基于双水听器接收信号互相关函数和单水听器接收信号自相关函数的水下声源距离深度联合估计方法。首先假设声源深度位于50m~300m之间,根据双水听器互相关函数提取直达波到达时间差估计水下声源距离,然后根据距离估计结果以及单水听器自相关函数提取的直达波与海面反射波时延差估计水下声源深度,最后计算声源深度估计结果的平均值再与双水听器互相关函数结合得到更为精确的距离估计结果。结果表明,采用此方法估计的水平距离相对误差在10.5%以内,声源深度相对误差小于13.3%。      

基于小波变换与深度残差融合的图像增强算法

针对目前基于小波变换图像融合增强算法原始图 像中的多尺度细节信息的不足,提 出了一种改进的多尺度小波变换与深度残差选择相结合的图像增强算法。利用小波变换对原 始图像进行分解提取得到它的多级分解系数后,再利用不同规则对不同层次的小波系数进行 重构,与此同时引入深度残差算法的思想对子带系数做残差。对于高频子带系数,计算子带 残差的系数与梯度特征融合方法的系数,选用两者最大值进行融合增强;而对于低频子带系 数则采用梯度特征融合增强系数与子带残差系数取平均值的算法进行融合。通过在MATLAB 平台上的实验对所提出算法进行验证,峰值信噪比相较于对比的方法都有所提高,且均方根 误差也得到减小,结构相似度都得到提高,结果表明该算法能增强图像的多尺度细节信息, 提高图像的信噪比,且具有更好的图像增强效果。     

基于Chan算法的水下测控设备组网数据融合技术研究

依据水下测控设备组网系统的工作特点,为了有效挖掘现有测控设备的使用效能,构建高精度的综合性水下测控网络,该文提出基于Chan算法的水下测控设备组网集中式数据融合定位算法。该算法首先利用基于波达时间的加权最小二乘算法粗测目标位置,然后依据该目标位置和测量时延信息的关系,构造新的误差矢量,利用该误差矢量再次加权最小二乘估计解算目标位置。研究结果表明,该算法可实现多套水下测控设备的数据融合,可有效提高全域范围的定位精度,且精度高于纯基于波达时间的融合定位算法。     

一种改进的CNN端到端自编码器通信系统

针对现有端到端神经网络通信系统的泛化能力改进及自编码器优化等问题,提出了一种基于卷积神经网络(Convolutional Neural Network,CNN)的端到端通信系统改进方案。该方案在自编码器结构中引入一维卷积层(Conv1D),通过对参数的重新设计,优化了网络性能。发送端采用多层Conv1D对输入序列进行特征提取,通过训练获得发送信号的最佳调制和编码方案;接收端同样采用多层Conv1D,来恢复受到噪声污染的符号。仿真实验表明,在不同输入比特长度及编码速率条件下,所提系统表现出了良好的泛化能力。并且,在加性高斯白噪声信道和瑞利衰落信道下,训练模型的误码性能与传统的调制方式性能相吻合,验证了系统方案的可行性和有效性。此外,对于数字传输常见的突发信道,所提方案具有良好的适应性,可获得1 dB左右误码性能的改善。     

A 3-Tier UWB-Based Indoor Localization System for Ultra-Low-Power Sensor Networks

We present a 3-tier UWB-based indoor localization system. It consists of a large number of energy-scavenging-based cost-effective transmit-only tags, a small number of batterypowered hubs as relay stations and a few base stations. This hierarchical scheme is driven by the energy available at each node. Localization is based on the arrival time of the UWB pulses at reference nodes.We describe how the coordinates and transmit time of a tag are determined and how the ambiguous solution is eliminated with the proper geometry of 4 reference nodes. We formulate where to place the hubs as an optimization problem. The localization performance of the system is investigated as a function of several parameters such as non-ideal hub placement, hub localization error and TOA error.     

基于双星TDOA和主星DOA的空中动目标联合定位技术

现有基于星载的空中动目标定位方法工程实现复杂度与代价过大,本文提出了一种应用于空中动目标定位的新型双星定位技术,联合双星到达时差信息（TDOA）和主星来波方向信息（DOA）可以获得目标的三维定位.通过矢量求解方法,建立了空中动目标定位的数学模型.同时,在考虑多种误差因素的前提下,建立了用于Monte Carlo分析的定位误差模型.最后,以空间站及其辅星作为应用场景进行了算例仿真.结果表明该技术能够实现空中动目标的地面航迹和三维位置的精确估计,可应用于空间站与卫星联合的空中动目标联合定位系统.     

Diagnostics of Analog Circuits Based on LS-SVM Using Time-Domain Features

Most researchers use wavelet transforms to extract features from a time-domain transient response from analog circuits to train classifiers such as neural networks (NNs) and support vector machines (SVMs) for analog circuit diagnostics. In this paper, we have proposed some new feature selection methods from a time-domain transient response, and compared the diagnostic results based on a least squares SVM (LS-SVM) using different time-domain feature vectors. First, we have improved two traditional feature selection methods: (a) using the mean and standard deviation in wavelet transform features, and (b) using the mean, standard deviation, skewness, kurtosis, and entropy in statistical property features. Then, a conventional time-domain feature vector based on the impulse response properties of a control system has been proposed. The simulation experiments for a leapfrog filter and a nonlinear rectifier show that: (1) the two improved methods have better accuracy than the traditional methods; (2) the proposed conventional time-domain feature vector is effective in the diagnostics of analog circuits—over 99 % for both of the two example circuits; (3) the proposed diagnostic method can diagnose soft faults, hard faults, and multi-faults, regardless of component tolerances and nonlinearity effects.     

An FBG impact location system based on broadband light source and improved TDoA algorithm

When a structure material is damaged by impact events, the reliability and lifetime of the material will be severely affected. So impact location is considered as the prime approach for structural health and damage monitoring. In this study, a novel fiber Bragg grating (FBG) impact location system based on broadband light source is designed, aiming at the shortcoming of existing location systems based on FBG. An improved localization algorithm based on the time difference of arrival (TDoA) is proposed for impact location. According to this algorithm, the impact position can be accurately predicted without wave velocity. Impact planar location experiments are carried out for verification of the FBG impact location system and algorithm on a400 mm×400 mm×3 mm aluminum alloy plate. The resulted locating error shows high precision and good stability of the proposed system. This work has been supported by the National Natural Science Foundation of China (Nos.61503218, 61403233, 61573226 and 61473176), the Excellent Young and Middle-Aged Scientist Award Grant of Shandong Province of China (No.BS2013DX018), and the Natural Science Foundation of Shandong Province for Outstanding Young Talents (No.ZR2015JL021). E-mail:pangdan@163.com      

基于融合改进RANSAC光流法的无人机视觉SLAM研究

针对同时定位与建图(SLAM)中存在定位精度不足、匹配特征点误差累积和特征匹配时间较长,提出了一种融合改进RANSAC光流法的优化算法。该方法基于传统RANSAC算法,加入最小二乘法对模型进行迭代优化来估计最优模型,对光流法的误匹配点进行剔除,大量减少图像误匹配特征点;把融合改进后的RANSAC光流法与特征点通过卡尔曼滤波进行融合,最后使用改进后的算法在公开的EuRoC MAV数据集中进行SLAM定位精度实验。实验结果表明：该改进算法能够有效减小光流法特征匹配的误差,从而提高无人机视觉SLAM的定位精度。     

基于多个传感器的VLC室内定位算法研究

为了实现移动机器人的快速高精度定位,提出了一种基于多个传感器的室内定位模型,研究了其可见光通信技术(VLC)室内定位算法,并对该算法进行了实验验证。首先研究基于AOA定位算法,利用传感器的响应曲线,结合室内定位模型,通过拟合预测算法计算出信号到达角度实现定位;然后综合多个传感器的定位模型和AOA定位算法,分析得出一种室内定位的实现方式,通过实验验证了该定位模型和定位算法的实现可行性。结果表明:其定位精度达13.6cm,定位周期为0.1s,相较于传统的AOA定位算法,该算法定位精度高、成本低、可行性高且定位速度快。     

Acoustic Source Localization in Wireless Sensor Network

In this paper, we consider the problem of acoustic source localization in a wireless sensor network based on different measured signal quantities, such as the received signal strength (RSS), the angle of arrival (AOA) and the time of arrival (TOA). For each of these quantities, an appropriate weighted least squares criterion function is developed to be used for sound source localization. The weights of each criterion function take into account the decrease in the signal-to-noise ratio (SNR) with distance from the source. In addition, RSS localization algorithm proposed in this paper provides improvement of the localization accuracy for low SNR. Finally, separate criterion functions for RSS, TOA and AOA are used together to obtain minimal localization error and maximal reliability of the acoustic source localization. Simulation analysis confirms improved performance of the proposed localization algorithm.     

A non-competing hybrid optical burst switch architecture for QoS differentiation

In this paper, we present a new hybrid optical burst switch architecture (HOBS) that takes advantage of the pre-transmission idle time during lightpath establishment. In dynamic circuit switching (wavelength routing) networks, capacity is immediately hard-reserved upon the arrival of a setup message at a node, but it is used at least a round-trip time delay later. This waste of resources is significant in optical multi-gigabit networks and can be used to transmit traffic of a lower class of service in a non-competing way. The proposed hybrid OBS architecture, takes advantage of this idle time to transmit one-way optical bursts of a lower class of service, while high priority data explicitly requests and establishes end-to-end lightpaths. In the proposed scheme, the two control planes (two-way and one-way OBS reservation) are merged, in the sense that each SETUP message, used for the two-way lightpath establishment, is associated with one-way burst transmission and therefore it is modified to carry routing and overhead information for the one-way traffic as well. In this paper, we present the main architectural features of the proposed hybrid scheme and further we assess its performance by conducting simulation experiments on the NSF net backbone topology. The extensive network study revealed that the proposed hybrid architecture can achieve and sustain an adequate burst transmission rate with a finite worst case delay.     

Cooperative localization for next-generation converged networks with closed-form solution

In this article, a novel cooperative wireless localization scheme based on information fusion is proposed. The scheme combines large-scale arrival time and small-scale distance measurements obtained from the next-generation converged networks. The maximum likelihood (ML) estimate of the terminai's position is derived with closed-form solution, and the Cramtr-Rao lower bound (CRLB) of the estimate error is investigated. Both theoretical analysis and simulation results verify that the proposed localization scheme can significantly enhance the location precision. Moreover, the mean square error of position estimate approximates the CRLB when the number of reference stations increases, which indicates that the proposed ML estimator is asymptotically efficient.     

基于小波变换的网络流量异常监测仿真实验

为有效定位识别和提取网络流量序列的暂态性异常特征,针对网络异常流量特征扰动性和暂态性特点,提出一种基于小波分解的二叉分类回归决策树主分量特征优化跟踪特征提取算法。利用训练集建立决策树模型,采用二叉分类回归决策树模型进行主分量特征优化跟踪建模,利用双正交提升小波分解得到的各层细节信号对暂态性扰动特征的敏感性,通过小波分解得到各层细节信号,将提取的小波分层细节信号的奇异值分解特征再返回到决策树主分量特征优化跟踪模型中,实现网络流量异常特征的定位提取和识别。仿真实验表明,改进算法的抗干扰能力和分辨率提高显著,暂态性异常特征谱图分辨能力提高,异常特征分布谱清晰可见,展示了较好的特征提取和状态识别性能。     

A burst-mode word-serial address-event link-III: analysis and test results

We present results for a scalable multiple-access inter-chip link that communicates binary activity between two-dimensional arrays fabricated in deep submicrometer CMOS. Capacity scales with integration density because an entire row is read and written in parallel. Row activity is encoded in a burst: The row address followed by a column address for each active cell. We predict the distribution of burst lengths when transmission is initiated by active cells and access is arbitered using a two-level queuing model. Agreement with the experiment is excellent for loads over 50% but not for lighter loads, where our assumption that service time is exponentially distributed breaks down. We also quantify the throughput-latency tradeoff. The price of an n-fold increase in throughput is an n per N/sub col/ timing error in a cell's inter-event interval, where N/sub col/ is the number of cells per row. Links implemented in 0.6, 0.4, and 0.25 /spl mu/m are compared; the highest burst-rate achieved was 27.8 M events/s.