UWB TEM HORN ANTENNA FOR THE ASPHALT PAVEMENT INVESTIGATION简

A simple Ultra-WideBand （UWB） exponentially-tapered Transverse ElectroMagnetic （TEM） horn antenna is presented for the asphalt detection based on Ground Penetrating Radar （GPR） In order to reduce the reflections from the antenna aperture, some absorbing material is loaded on the outer surface of the conductor. Comparing with the traditional TEM horn antenna, the proposed antenna has a small size and a large impedance bandwidth. Simulated and measured results show that the proposed TEM horn antenna has a low Voltage Standing Wave Ratio （VSWR） below 2 over the whole band from 0.35 GHz to 12 GHz, good radiation characteristics, and small late-time ringing, which can perfectly meet the requirements of the GPR application.     

PARAMETERS DETERMINATION METHOD OF PHASE-SPACE RECONSTRUCTION BASED ON DIFFERENTIAL ENTROPY RATIO AND RBF NEURAL NETWORK简

Phase space reconstruction is the first step of recognizing the chaotic time series. On the basis of differential entropy ratio method, the embedding dimension mopt and time delay τ are op- ritual for the state space reconstruction could be determined. But they are not the optimal parameters accepted for prediction. This study proposes an improved method based on the differential entropy ratio and Radial Basis Function （RBF） neural network to estimate the embedding dimension rn and the time delay τ, which have both optimal characteristics of the state space reconstruction and the prediction. Simulating experiments of Lorenz system and Doffing system show that the original phase space could be reconstructed from the time series effectively, and both the prediction accuracy and prediction length are improved greatly.     

DEVELOPMENT OF NEW PILL-BOX WINDOW FOR S-BAND HIGH POWER KLYSTRON简

In this paper, a new pill-box window with arc groove disk is studied for S-band high power klystron. Its main characteristics are long pill-box and periodic grooved window disk. The long pill-box window can decrease the normal field and relieve the radio frequency loss in high power transmission, and periodic grooved window disk can suppress tangential field multipactor. The Monte Carlo （MC） method is used to build up the simulation model and analyze the increasing tendency of electrons. The simulation results indicate that long-box window with periodic are grooved window disk can restrain multipactor effectively. Homocentric circular half-camber arc slot is put forward to overcome the disadvantages of periodic straight triangle and strait rectangular. The long pill-box with groove disk window prototype is tested in high power Travelling Wave Resonant Ring （TWRR） and the experi- mental results show an excellent character of this window.     

EFFICIENT STRIP-MODE SAR RAW SIGNAL SIMULATION OF MIXED TARGETS BASED ON ACCURATE 2-D SPECTRUM简

An accurate and efficient Synthetic Aperture Radar （SAR） raw data generator is of con- siderable value for testing system parameters and verifying imaging algorithms. Nevertheless, the ex- isting simulator cannot exactly handle the case of the fast moving targets in high squint geometry. As for the issue, the analytical expression for the two Dimensional （2-D） signal spectrum of moving targets is derived and a fast raw echo simulation method is proposed in this study. The proposed simulator can accommodate the moving targets in tile high squint geometry, whose processing steps of the simulation are given in detail and its computational complexity is analyzed. The simulation data for static and moving targets are processed and analyzed, and the results are given to validate the effectiveness of the proposed approach.     

WIDE SWATH FMCW SAR DATA PROCESSING IN SQUINT MODE简

This paper concentrates on the data processing of Frequency Modulation Continuous Wave （FMCW）, Synthetic Aperture Radar （SAR） in the case of wide swath and squint mode. In the mode, the Doppler centroid dramatically varies along slant range compared to conventional pulsed-SAR. This poses a challenge for system design and signal processing since a very large azimuth bandwidth would be introduced. In the paper, we accommodate the Doppler centroid variations with range by an im- proved spectral-length extension method, where a bulk range shift and updated Doppler centroid variations are introduced to greatly reduce the azimuth aliasing with respective to the existing methods Moreover, an image formation approach that integrates wave number domain algorithm is presented to focus the raw data of FMCW SAR in the case of wide swath and squint mode. Point target simulation experiment demonstrates the advantages of the presented method.     

NEW APPROACH TO EMULATE SEU FAULTS ON SRAM BASED FPGAS简

Field Programmable Gate Arrays （FPGAs） offer high capability in implementing of com- plex systems, and currently are an attractive solution for space system electronics. However, FPGAs are susceptible to radiation induced Single-Event Upsets （SEUs）. To insure reliable operation of FPGA based systems in a harsh radiation environment, various SEU mitigation techniques have been provided In this paper we propose a system based on dynamic partial reconfiguration capability of the modern devices to evaluate the SEU fault effect in FPGA. The proposed approach combines the fault injection controller with the host FPGA, and therefore the hardware complexity is minimized. All of the SEU injection and evaluation requirements are performed by a soft-core which realized inside the host FPGA Experimental results on some standard benchmark circuits reveal that the proposed system is able to speed up the fault injection campaign 50 times in compared to conventional method.     

IMAGING ANALYSIS OF FREQUENCY MODULATION CONTINUOUS WAVE SYNTHETIC APERTURE RADAR IN NEAR RANGE MODE简

Frequency-Modulation Continuous-Wave Synthetic Aperture Radar （FMCW SAR） has shown great potential in the applications of civil and military fields because of its easy deployment and low cost. However, most of these work and analysis are concentrated on airborne FMCW SAR, where the characteristics of the ilnaging geometry and signal are much similar to that of traditional pulsed-SAR. As a result, a series of test campaigns of automobile-based FMCW SAR were sponsored by Institute of Electronics, Chinese Academy of Sciences （IECAS） in the autumn of 2012. In this paper, we analyze the imaging issues of FMCW SAR in automobile mode （named as near range mode）, where a vehicle is used as moving platform and a large looking angle is configured. The imaging geometry and signal properties are analyzed in detail. We emphasize the difference of the near range mode from the traditional airborne SAR mode. Based on the analysis, a focusing approach is proposed in the paper to handle the data focusing in the case. Simulation experiment and real data of automobile FMCW SAR are used to validate the analysis.     

INPAINTING ALGORITHM FOR KINECT DEPTH MAP BASED ON FOREGROUND SEGMENTATION简

The depth information of the scene camera, and depth extraction is a key technology indicates the distance between the object and the in 3D video system. The emergence of Kinect makes the high resolution depth map capturing possible. However, the depth map captured by Kinect can not be directly used due to the existing holes and noises, which needs to be repaired. We propose a texture combined inpainting algorithm in this paper. Firstly, the foreground is segmented combined with the color characteristics of the texture image to repair the foreground of the depth map. Secondly, region growing is used to determine the match region of the hole in the depth map, and to accurately position the match region according to the texture information. Then the match region is weighted to fill the hole. Finally, a Gaussian filter is used to remove the noise in the depth map. Experimental results show that the proposed method can effectively repair the holes existing in the original depth map and get an accurate and smooth depth map, which can be used to render a virtual image with good quality.     

绝缘子表面裂纹激光超声检测简

为了实现在役绝缘子裂纹的带电检测,采用脉冲激光非接触方式在瓷瓶表面激励超声波,用宽带超声换能器接收声波,并用这种非接触发射-接触接收声波的方法,对含有人工刻槽的棕釉高压瓷质绝缘子表面裂纹进行了检测实验,通过可视化成像检测系统,对声波在被检样品中传播的动态波形进行了实时观察,获得缺陷最大振幅图。结果表明,该方法在绝缘子裂纹远程检测方面具有适用性,且检测不受绝缘子复杂曲面形状的影响。     

一种宽带全向圆极化天线简

 基于环天线-偶极子模型,本文提出一种宽带全向圆极化天线.天线包含四对围绕圆柱放置的倾斜振子和一个宽带馈电网络.每对振子包含一个主辐射振子和一个用以增加带宽的寄生振子.馈电网络包括四个宽带巴伦和一个阻抗匹配电路.实验结果表明,该天线15-dB回波损耗带宽和3-dB轴比带宽分别为31%（1.68-2.31GHz）和30%（1.7-2.3GHz）,水平面不圆度小于1dB.     

基于稀疏表示的SAR图像属性散射中心参数估计算法

考虑目标频率-方位2维观测数据在属性散射中心模型参数空间上的稀疏性,该文提出一种基于稀疏表示的属性散射中心提取与参数估计方法。由于模型参数维数较高,构造的高维联合字典将消耗较多系统资源。该算法通过分别构建包含位置信息与方位属性参数信息的两个低维字典代替高维的联合字典实现距离特性与方位特性的解耦合,以降低资源需求,并通过正交匹配追踪(OMP)-RELAX联合算法求解l0优化问题,从而实现在频率-方位角域上位置参数与方位属性参数的联合估计。根据提取的属性散射中心可以有效地估计目标或目标重要部件的几何尺寸。基于电磁计算数据和实测数据的实验结果验证了该算法的有效性。     

基于子空间的三阶多项式相位信号快速稀疏分解算法

针对稀疏分解冗余字典中原子数量庞大的缺点,该文提出一种三阶多项式相位信号的快速稀疏分解算法。该算法根据三阶多项式相位信号的特点,把原有信号变换成两个子空间信号,并根据这两个子空间信号构建相应的冗余字典,然后采用正交匹配追踪法来完成其稀疏分解,最后利用稀疏分解原理完成原有信号的稀疏分解。该算法把原有信号变换成两个不同子空间信号,构建了两个不同的冗余字典,对比采用一个冗余字典库,这种采用两个冗余字典的算法大大减少了原子数量,并且通过快速傅里叶变换,在一个冗余字典进行稀疏分解时,同时找到另一个冗余字典中的最匹配的原子。因此该算法通过减少原子数量和采用快速傅里叶变换大大加快了稀疏分解速度。实验结果表明,相比于采用Gabor原子构建的冗余字典,采用匹配追踪算法与遗传算法及最近提出的基于调制相关划分的快速稀疏分解,它的稀疏分解速度更快,并且具有更好的收敛性。     

基于优化的正交匹配追踪声音事件识别

针对各种环境声对声音事件识别的影响,该文提出一种基于优化的正交匹配追踪(Orthogonal Matching Pursuit, OMP)声音事件识别方法。首先,利用OMP稀疏分解并重构声音信号,保留声音信号的主体部分,减小噪声的影响。其中,使用粒子群(Particle Swarm Optimization, PSO)算法优化搜索最优原子,实现OMP的快速稀疏分解。接着,对重构声音信号提取Mel频率倒谱系数(Mel-Frequency Cepstral Coefficients, MFCCs),与OMP时-频特征和基频(PITCH)特征,组成优化OMP的复合特征。最后,通过优化OMP复合特征,使用随机森林(Random Forests, RF)对40种声音事件在不同环境不同信噪比下进行识别。实验结果表明,优化OMP复合特征结合RF的方法能有效地识别各种环境下的声音事件。     

基于自适应逼近残差的稀疏表示语音降噪方法

该文提出一种基于自适应逼近残差的稀疏表示语音降噪方法。在字典学习阶段基于K奇异值分解(K-Singular Value Decomposition, K-SVD)算法获得干净语音谱的过完备字典,在稀疏表示阶段基于权重因子调整后的噪声谱和估计的交叉项对逼近残差持续自适应地更新,并采用正交匹配追踪(Orthogonal Matching Pursuit, OMP)方法对干净语音谱进行稀疏重构。最后结合估计的干净语音谱与带噪语音相位,通过傅里叶逆变换获得重构的干净语音。实验结果表明所提方法在不同噪声和信噪比条件下相比标准的谱减法,稀疏表示语音降噪算法和基于自回归隐马尔可夫模型的降噪方法有更好的降噪效果。     

基于改进正交匹配追踪算法的压缩感知雷达成像方法

运算复杂度高是基于压缩感知(CS)的雷达成像方法走向实用亟待克服的难题。该文利用雷达目标散射率分布的稀疏性,研究了基于改进正交匹配追踪(OMP)算法的2维联合压缩成像方法。首先建立了步进频雷达回波的稀疏表示模型,根据稀疏字典和压缩测量的2维可分离特性,提出一种改进的OMP算法用于雷达图像形成,大大提高了计算效率,并很容易扩展到其他贪婪类算法中。从理论上对几种CS成像算法的性能及资源需求进行了分析比较,表明所提供的算法相比常规的CS算法在存储量和计算量上均具有显著的优势,仿真及暗室数据实验验证了所提成像算法的有效性。     

基于块A*正交匹配追踪的多传感器数据联合重构算法

针对A*正交匹配追踪(A*OMP)算法计算复杂高,且不能利用信号的结构稀疏性这一缺陷,该文提出了块A*OMP算法并将其用于解决分布式压缩感知中的信号联合重构问题。该算法用原子块取代单个原子作为搜索树中的节点,在计算路径代价时用搜索树中所有路径的最大长度取代信号的稀疏度。然后在块A*OMP算法的基础上,选择与残差矩阵投影误差最小的原子块作为新的节点,得到了一种用于解决MMV(Multiple Measurement Vector, MMV)问题的块A*OMP算法,并利用该算法对相邻区域内的多个传感器所测的温度信号进行了联合重构。实验结果表明,该算法的重构性能优于MMV正交匹配追踪(OMPMMV)算法。     

高速移动通信系统中OTFS信道估计算法研究

针对高速移动环境中双色散信道会出现信道估计可靠性下降的问题,该文在正交时频空(OTFS)调制系统的输入-输出模型中提出一种基于压缩感知的信道估计算法。该算法利用信道中最大多普勒频移和最大时延确定导频发送矩阵的大小,相比传统的正交匹配追踪(OMP)信道估计算法,能够在保证相似信道估计准确度的情况下节省导频资源;并在此基础上,对OTFS调制符号做相位旋转,增加差分矩阵的秩,理论分析和仿真结果表明,该方案能够提升OTFS系统的分集阶数进而降低噪声的干扰。     

基于扩展路径识别算法的水声OFDM系统低复杂度迭代稀疏信道估计

移动OFDM水声通信系统中,基于压缩感知的稀疏信道估计方法计算量较大,不适用于实时通信.针对这一问题,该文基于一致多普勒信道模型提出一种扩展路径识别(GPI)算法.该方法首先使用信道多普勒扩展矩阵构造等效发射序列,将多普勒信道转化为等效线性时不变信道.然后使用GPI算法估计信道多普勒及各路径的时延及幅度参数,实现低复杂...     

一种改进的水声正交频分复用稀疏信道时延估计算法

水声正交频分复用(OFDM)系统中,采用传统正交匹配追踪(OMP)方法估计离网格(off-grid)时延时,需要很高的过采样因子和高昂的计算开销.针对传统OMP方法估计离网格时延计算复杂度高的问题,该文借鉴多元线性拟合思想引入路径补偿的概念,提出了一种基于路径补偿的改进OMP时延估计算法,用以补偿从离网格路径向其周围网...     

基于改进压缩感知的缺损光纤Bragg光栅传感信号修复方法

光纤光栅传感在实际的应用中,存在采样信号数据丢失问题,该文提出一种改进重构算法的压缩感知信号修复方法。根据缺损信号特征,选取与之匹配的观测矩阵与稀疏字典。基于压缩感知重构算法,提出匹配光纤布拉格光栅(FBG)信号特征的自适应阈值函数,同时增设阈值判决条件。分析了信号修复与传感测量精度的关系,采用重建信号的寻峰误差来验证信号的修复效果。仿真结果显示,在FBG光谱数据缺失30%的情况下,恢复信号的平均相对误差为10-6;均方根误差为0.0707,比对比算法低0.0232~0.1159;且系统平均运行时间远低于对比算法,表明采用该文算法修复缺损的FBG传感信号具有较高的重构精度与较好的实用性。