相机阵列中无视场重合图像时间配准方法研究

多路商业相机组阵在进行信息融合与视场拼接之前需要对采集的多路图像进行时间配准。为保证通用性,需要研究一种与系统相对独立的多路图像时间配准方法。提出一种利用多路图像序列内变换关系的算法,首先提取多路图像中与时间相关的共同特征,然后通过改进的奇异值分解方法判定共同特征的相似度完成时间配准。本文算法不需要提前对相机进行标定,对序列内图像配准精度要求较低,且能够在多路图像之间没有视场重合的情况下完成时间配准。经实验验证,配准精度达到了亚帧级。     

High-speed ground moving target detection research using triangular modulation FMCW

The frequency modulated continuous wave (FMCW) radar has the characteristics of low probability of interception, good hidden property and the ability to counter anti-radiation missiles. This paper proposes a new method for high-speed ground moving target detection (GMTD) using triangular modulation FMCW. According to the characteristic of the opposite range shift induced by the upslope and downslope modulation FMCW, the upslope and downslope are imaged, respectively. After compensation of continuous motion of the platform and time difference between upslope and downslope signals for imaging, the moving target can be detected through displaced phase center antenna (DPCA) technology. When the moving target is detected, the moving target image is extracted, and correlation processing is used to obtain the range shift, which can be used to estimate the target radial velocity, and further to find the real position of the target. The effectiveness of this method is verified by the result of computer simulation. __________ Translated from Journal of Xidian University, 2008, 35(4): 586–591 [译自: 西安电子科技大学学报(自然科学版)]     

Computers detecting inferior printing quality and errors

As observed, the described approach to computer-aided error detection in printed matter proves itself to be exact and reliable. Our prototype printing error detection computer program has also undergone extreme testing in an industrial environment. The problem of excessive detection duration will have to be solved by an optimization of the registration and interpolation procedures. When considering the coarse image registration, a solution in the frequency domain seems appealing, where the translational and rotational information can be extracted from the phase and amplitude spectra, respectively. Fine image registration must be optimized even more. One of the ways we are presently researching tries to minimize the quantity of data included in the computation, at each iteration. We can do this by using images with lower resolution or taking into registration only an image's segment. Afterwards, the obtained registration parameters would be applied to the original-size images. For the time being, a second optimization attempt with partial images seems the most promising.     

CFAR detection of weak target in clutter using chaos synchronization

In this paper, a novel constant false alarm rate (CFAR) approach for detecting weak targets in sea clutter spectrum based on chaos synchronization is proposed. The weak target signal is detected when the synchronization between two identical chaotic systems is realized, even if the target spectrum lies inside the clutter spectrum. The threshold for the proposed CFAR detection is derived theoretically. The proposed chaos‐synchronization‐based CFAR technique is shown to be able to enhance the detectability of the target when the signal‐to‐clutter ratio and signal‐to‐noise ratio are low. Numerical experiments based on real radar sea clutter data confirm the effectiveness of the proposed chaos‐synchronization‐based CFAR detection method. The performance is superior to those of the standard autoregressive estimation‐based and the cell‐averaging CFAR detectors. Copyright © 2007 John Wiley & Sons, Ltd.     

DBS imaging and GMTI in a wideband airborne mechanic scanning radar

A principle for choosing the coherent integration number and an improved Doppler beam sharpening (DBS) imaging algorithm for mechanic scanning radar are presented in this paper. By compensating the range migration in wideband airborne mechanic scanning radar, the proposed DBS imaging algorithm can efficiently improve the resolution of a DBS image. In addition, based on the characteristic that the echo from the moving target will be modulated by the antenna pattern, a novel method used to locate the moving target is also presented, which begins with the sub-aperture moving target detection followed by the sliding window detection. Proper location can be achieved by using this method. Finally, the results on real radar data are provided to demonstrate the effectiveness of these proposed methods. __________ Translated from Journal of Xidian University (Nature Science), 2006, 33(1): 116–120 (in Chinese)     

杂波先验知识未确知场景下 MIMO雷达收发联合优化

针对杂波初始估计误差导致多输入多输出(MIMO)雷达检测稳健性较差的问题,提出了发射波形与接收权联合优化方法以改善MIMO雷达检测稳健性。杂波误差凸集、波形恒模特性和相似约束下,基于最大化输出信干噪比准则,首先构建了改善最差情况下MIMO雷达检测性能的极大极小联合优化问题;而后,为求解所得NP-hard问题,将其分解为内外层子问题,并交替迭代求解。与不相关信号、非稳健及现有稳健方法相比,数值仿真验证了所提方法的有效性。     

Optimized placement of nodes for target detection in sensor networks

In order to improve the precision of the target detection in wireless sensor networks, a new approach based on genetic algorithm (GA) was proposed to optimize the placement of the sensor. The target location problem was transformed into locating a target at a grid point through modeling the sensor field as a grid of points. Moreover, the sensor placement problem was formulated as a combinatorial optimization problem, which is aimed at minimizing the maximum discrimination error under the restraints of limited cost and complete coverage. The GA approach uses binary coding to represent the location, and both single parent cross-over operator and single parent mutation operator are used to improve its speed and efficiency. Experimental results have shown that a global optimal solution can be quickly obtained using the proposed method and the precision requirement for target location is satisfied. Translated from Journal of Xi’an Jiaotong University, 2006, 40(8): 906–910 [译自: 西安交通大学学报]     

基于隐马尔可夫模型的MIMO雷达目标检测

MIMO雷达是一种新体制雷达,相对于传统雷达在目标检测及参数估计性能都有很大提高。本文针对MIMO雷达的发射信号特点及天线阵元布置特点,分析了雷达目标和杂波的散射特点。目标回波的各向异性比杂波更强。因此可以用隐马尔可夫模型（HMM）对目标和杂波分别建模,实现目标和杂波的分离。在检测过程中,首先用样本模型对HMM进行训练,得出它的参数。然后用训练好的HMMs分别对待检测信号进行归类,分别计算它属于杂波和目标的概率,计算概率比值,大于门限判断有目标。仿真实验表明,本文方法的检测性能优于传统的检测方法。本方法在检测时候的计算量很小,有利于信号的实时处理。     

Novel anomaly detection approach for telecommunication network proactive performance monitoring

The mode of telecommunication network management is changing from “network oriented” to “subscriber oriented”. Aimed at enhancing subscribers’ feeling, proactive performance monitoring (PPM) can enable a fast fault correction by detecting anomalies designating performance degradation. In this paper, a novel anomaly detection approach is the proposed taking advantage of time series prediction and the associated confidence interval based on multiplicative autoregressive integrated moving average (ARIMA). Furthermore, under the assumption that the training residual is a white noise process following a normal distribution, the associated confidence interval of prediction can be figured out under any given confidence degree 1 - α by constructing random variables satisfying t distribution. Experimental results verify the method’s effectiveness.     

基于STAP的机载雷达弱目标检测前跟踪

针对载机运动及地杂波场景下的弱目标检测跟踪问题,提出了一种基于空时自适应处理的检测前跟踪算法.在目标检测跟踪处理之前,首先利用空时自适应处理抑制杂波和噪声;接着采用脉冲压缩进行距离处理;最后在原始观测数据基础上,采用Viterbi算法进行目标检测与航迹恢复.仿真结果表明此算法可以提高弱目标的检测概率及跟踪概率.     

动态杂波条件下非合作辐射源目标检测研究

针对非合作雷达辐射源采用不可控的第三方辐射源导致杂波趋于复杂的问题,提出了根据杂波协方差矩阵特点进行杂波动态化的方法,设计了对杂波动态化处理的非合作雷达辐射源目标检测系统。结果显示：所设置的辐射源与目标信息在杂波动态化处理后,可以通过非合作雷达辐射源目标检测系统提取到准确的辐射源、目标的位置、速度、角度信息。结果表明该动态化杂波不会轻易淹没功率较大的目标,该目标检测系统可以对目标进行数据采集处理,且位置速度误差均不超过1%,对目标跟踪、实际情况下的雷达信号处理有参考作用。     

Fault detection for a class of Markov jump systems with unknown disturbances

An optimized fault detection observer is designed for a class of Markov jump systems with unknown disturbances. By reconstructing the system, the residual error dynamic characteristics of unknown input and fault signals, including unknown disturbances and modeling error are obtained. The energy norm indexes of disturbance and fault signals of the residual error are selected separately to reflect the restraint of disturbance and the sensitivity of faults, and the design of the fault detection observer is described as an optimization problem. By using the constructed Lyapunov function and linear matrix inequalities, a sufficient condition that the solution to the fault detection observer exists is given and proved, and an optimized design approach is presented. The designed observer makes the systems have stochastic stability and better capability of restraining disturbances, and the given norm index is satisfied. Simulation results demonstrate that the proposed observer can detect the faults sensitively, and the influence of unknown disturbance on residual error can be restrained to a given range. __________ Translated from Journal of Xi’an Jiaotong University, 2007, 41(4): 458–462 [译自 : 西安交通大学学报]     

一种图像确认目标的多目标跟踪方法

为了解决回波的复杂性和不确定性导致雷达多目标跟踪精度降低的问题,给出一种图像确认的多目标跟踪方法。该方法通过序列图像获取目标部分相关参数,从而剔除与参数不相符的虚假回波和杂波;然后根据保留的目标回波更新所跟踪目标的测量新计算,从而减少了多目标跟踪中由无关回波和杂波干扰所造成的测量更新误差,提高了目标跟踪的精度。仿真实验结果表明,本算法在去除部分或全部杂波后,能够减小多目标跟踪的误差,使跟踪精度得到较大改善。     

微多普勒通道间特性对SAR GMTI性能影响分析

现实环境中,地面目标在具有平动的同时常会叠加周期性的微动,如汽车的怠速抖动等.传统的合成孔径雷达地面运动目标检测技术(SAR-GMTI)主要集中于目标匀速、匀加速等平动形式,无法对微动造成的非线性相位历程进行处理.而目标微动产生的微多普勒会在SAR成像中使目标沿方位向出现等间隔的散焦点——"鬼影点".按照传统的GMTI理论,目标平动速度很小时,其多普勒很难与杂波区分,从而无法实现目标检测.通过对机载多通道SAR"一发多收"模式下地面振动目标运动建模,推衍出了地面振动目标在不同通道内的图像域回波表达式及通道间各鬼影点的干涉相位.通过仿真验证了该干涉相位的正确性,并量化分析了随载频、振动角频率、径向平动速度变化时,各鬼影点空域导向与杂波导向的正交区分度,从而证明即使目标的平动多普勒很小甚至为零时,利用微多普勒带来的空域信息检测地面运动目标仍具有充分的可靠性.     

Design and performance analysis of LMS algorithm based adaptive filter embedded with CFAR detector under non‐homogeneous clutter scenarios

The paper presents performance analysis of least‐mean‐square algorithm based adaptive filter embedded with constant false alarm rate (CFAR) detector for the purpose of better detection of target under non‐homogeneous clutter environment in radar application. The objective of this paper is to develop a method by redesigning the radar detector in such a way to emphasize the target response and de‐emphasize the clutter response. The hardware implementation using pipeline technique for the adaptive filter reveals its capability to support high sampling frequency, which is an ardent necessity for high performance radar. The moderate area‐delay‐product and low power consumption have made it suitable for hardware realization for such application. The extensive MATLAB simulation of proposed design shows remarkable improvement of detection performance in terms of signal‐to‐noise ratio of 17 dB considering probability of detection at 0.8 over the generic cell averaging CFAR (CA‐CFAR). Copyright © 2015 John Wiley & Sons, Ltd.     

Error-space estimate method for generalized synergic target tracking

To improve the tracking accuracy and stability of an optic-electronic target tracking system, the concept of generalized synergic target and an algorithm named error-space estimate method is presented. In this algorithm, the motion of target is described by guide data and guide errors, and then the maneuver of the target is separated into guide data and guide errors to reduce the maneuver level. Then state estimate is implemented in target state-space and error-space respectively, and the prediction data of target position are acquired by synthesizing the filtering data from target state-space according to kinematic model and the prediction data from errorspace according to guide error model. Differing from typical multi-model method, the kinematic and guide error models work concurrently rather than switch between models. Experiment results show that the performance of the algorithm is better than Kalman filter and strong tracking filter at the same maneuver level. __________ Translated from Journal of University of Electronic Science and Technology of China, 2007, 36(2): 217–219 [译自: 电子科技大学学报]     

YOLOv4 与 ORB 深度融合的绝缘子识别定位研究

为了解决复杂背景下铁路接触网绝缘子的快速准确识别及定位问题,提出了一种YOLOv4目标检测算法和ORB特征匹配算法深度融合的绝缘子识别定位方法。首先利用迁移学习的策略训练YOLOv4检测网络,解决了绝缘子数据集样本较少导致过拟合的问题;然后采用高斯金字塔提取图像多尺度特征,使原始ORB算法具备尺度不变性;最后将以上两种算法融合,在双目相机获取的图像上标出绝缘子识别框,并在左右图像识别框内提取特征点进行匹配,利用视差原理还原出绝缘子相对于相机的三维坐标。实验结果表明,该方法可以有效地避免复杂背景干扰,准确地定位出绝缘子的三维坐标,4 m内最大定位误差为2.1%,检测速度为35 fps,具有较高的精确性和实时性。     

Robust adaptive beamforming algorithm based on Bayesian approach

The performance of adaptive array beamforming algorithms substantially degrades in practice because of a slight mismatch between actual and presumed array responses to the desired signal. A novel robust adaptive beamforming algorithm based on Bayesian approach is therefore proposed. The algorithm responds to the current environment by estimating the direction of arrival (DOA) of the actual signal from observations. Computational complexity of the proposed algorithm can thus be reduced compared with other algorithms since the recursive method is used to obtain inverse matrix. In addition, it has strong robustness to the uncertainty of actual signal DOA and makes the mean output array signal-to-interference-plus-noise ratio (SINR) consistently approach the optimum. Simulation results show that the proposed algorithm is better in performance than conventional adaptive beamforming algorithms. __________ Translated from Journal of Northeastern University (Natural Science), 2007, 28(6): 793–796 [译自: 东北大学学报 (自然科学版)]     

Indoor and outdoor people detection and shadow suppression by exploiting HSV color information

An adaptive background model based on maximum statistical probability and a shadow suppression scheme for indoor and outdoor people detection by exploiting hue saturation value (HSV) color information is proposed. To obtain the initial background scene, the frequency of R, G, and B component values for each pixel at the same position in the learning sequence are respectively calculated; the R, G, and B component values with the biggest ratios are incorporated to model the initial background. The background maintenance, or the socalled background re-initiation, is also proposed to adapt to scene changes such as illumination changes and scene geometry changes. Moving cast shadows generally exhibit a challenge for accurate moving target detection. Based on the observation that a shadow cast on a background region lowers its brightness but does not change its chromaticity significantly, we address this problem in the article by exploiting HSV color information. In addition, quantitative metrics is introduced to evaluate the algorithm on a benchmark suite of indoor and outdoor video sequences. The experimental results are given to show the performance of the algorithm. __________ Translated from Journal of Huaqiao University (Natural Science), 2007, 28(1): 30–33 [译自: 华侨大学学报 (自然科学版)]     

基于天幕靶与声靶的入靶参数检测及性能分析

为了准确检测弹丸的入靶参数,提高精度靶检测性能,在分析弹丸定位算法的基础上,建立基于天幕靶与声靶的五元定位模型,进一步提出一种弹丸入靶参数检测算法。根据模型间各阵元的矢量关系,推导出弹丸入靶参数的计算公式,实现弹丸入靶参数检测。利用阵列参数,偏航角和弹丸入靶坐标点到阵元中心距离与定位性能关系,对测距测向精度进行分析。结果表明,该算法弹丸入靶坐标最大误差为1.41%,方位角最大误差为1.23%,具有较好的弹丸入靶参数检测效果。