Scale effect removal and range migration correction for hypersonic target coherent detection

The detection of hypersonic targets usually confronts range migration(RM)issue before coherent integration(CI).The traditional methods aiming at correcting RM to obtain CI mainly considers the narrow-band radar condition.However,with the increasing requirement of far-range detection,the time bandwidth product,which is corresponding to radar’s mean power,should be promoted in actual application.Thus,the echo signal generates the scale effect(SE)at large time bandwidth product situation,influencing the intra and inter pulse integration performance.To eliminate SE and correct RM,this paper proposes an effective algorithm,i.e.,scaled location rotation transform(ScLRT).The ScLRT can remove SE to obtain the matching pulse compression(PC)as well as correct RM to complete CI via the location rotation transform,being implemented by seeking the actual rotation angle.Compared to the traditional coherent detection algorithms,Sc LRT can address the SE problem to achieve better detection/estimation capabilities.At last,this paper gives several simulations to assess the viability of ScLRT.

基于Attention-Inception网络集成的雷达HRRP序列目标识别方法

传统的雷达高分辨距离像(High Resolution Range Profile,HRRP)序列识别方法依赖于人工提取特征,并且在使用现有的经典深度学习方法识别小数据集时存在梯度消失和过拟合问题,导致收敛速度慢,识别率低。针对上述问题,提出了一种基于注意力机制的集成Inception网络模型,通过集成Attention-Inception单分支网络,实现了HRRP序列更深层次特征的提取;通过对模型的损失函数加入L2正则化,缓解小数据集在集成网络中的过拟合问题;利用Inception Ⅰ和Inception Ⅱ结构提取HRRP序列多尺度特征,并引入注意力机制计算特征序列的分配权重;加入残差结构,减缓了集成网络梯度消失问题。在预处理后的HRRP序列上进行实验结果表明,所提方法的目标识别率达到93.3%,并且与未去除噪声的HRRP序列相比目标识别率提高了14.67%。

ANALYSIS OF TARGET TRACKING BASED ON RANGE DIFFERENCE MEASUREMENT OF MULTISTATIC RADAR SYSTEM

An analysis is presented for target tracking with short range multistatic radar system in this paper. The velocity vector is introduced into the model to depict target motion more precisely. The system measurement equation is such constructed on the basis of range difference that make the tracking model independent of the transmitter position. Therefore the algorithm is very much suitable for the case that the transmitter is not fixed. Simulation results show that the algorithm has the advantages of fast tracking and small steady tracking errors, and can be used for tracking target in short range with multistatic radar system.

A NEW METHOD FOR DETERMINING THE LOCATION AND LENGTH OF A THIN CYLINDRICAL TARGET WITH RANGE DIFFERENCE OF A MULTISTATIC RADAR SYSTEM

This paper describes a short range target location system based on the range difference information of a T-R4 multistatic radar system with FMCW signal. A new method is proposed to determine the location and length of a thin cylindrical target making use of the high resolution of wide band FMCW signal and the spectrum characteristics of the target echo. Formulae are derived for target location and its length estimation being independent of the transmitter position. System performances are simulated with the proposed algorithm and the results are given for various situations.

Coordination of multiple mobile robots with limited communication range in pursuit of single mobile target in cluttered environment

This paper addresses the problem of coordinating multiple mobile robots in searching for and capturing a mobile target,with the aim of reducing the capture time.Compared with the previous algorithms,we assume that the target can be detected by any robot and captured successfully by two or more robots.In this paper,we assume that each robot has a limited communication range.We maintain the robots within a mobile network to guarantee the successful capture.In addition,the motion of the target is modeled and incorporated into directing the motion of the robots to reduce the capture time.A coordination algorithm considering both aspects is proposed.This algorithm can greatly reduce the expected time of capturing the mobile target.Finally,we validate the algorithm by the simulations and experiments.

OPTIMIZATION OF WEIGHTED HIGH-RESOLUTION RANGE PROFILE FOR RADAR TARGET RECOGNITION

For the recognition of high-resolution range profile （HRRP） in radar, the weighted HRRP can reduce the instability of range cells caused by the attitude change of targets. A novel approach is proposed to optimize the weighted HRRP. In the approach, the separability of weighted HRRPs in different targets is measured by de- signing an objective function, and the weighted coefficients are computed by using the gradient descent method, thus enhancing the influence of stable range cells. Simulation results based on five aircraft models show that the approach can effectively optimize the weighted HRRP and improve the recognition accuracy.

基于多重长PCR靶向捕获测序技术的高同源SNP鉴定

为建立一种高同源区段的单核苷酸多态性(SNP)基因分型技术,通过构建本地Blast对SNP所在的200和400 bp区段进行同源性评估,并筛选出高同源区段的SNP。利用第一轮多重长PCR(polymerase chain reaction)捕获329个样本的9个高同源区段SNP所在的长片段,使用纯化后的第一轮PCR产物作为模板进行扩增子建库测序,检测样本共得2 928个SNP位点信息,测序成功率高达98.885 6%。利用Hardy-Weinberg(HWE)法则计算试验研究的9个高同源区段SNP位点的基因频率(p值均大于0.05,符合HWE法则),并与NCBI(national center for biotechnology information)中千人基因组数据库中获取的基因频率相比对,发现二者单碱基基因频率一致(误差限<0.15)。研究表明,利用多重长PCR靶向捕获技术结合二代测序技术为高同源区段的SNP分型提供一个准确、快速、大样本检测方案。

Simulation of the RCS Range Resolution of Extremely Large Target

The high frequency hybrid technique based on an iterative Physical Optics(PC)) and the method of equivalent current (MEC) approach is developed for predicting rangeresolution of the Radar Cross Section (RCS) in the spatial domain. We introduce the hybrid highfrequency method to simulate range resolution of the extremely large target in the near zone. Thispaper applies this method to simulate the range resolution of the two 1 m X 1 m plates and the ship.The study improves the speed of simulatingthe range resolution of the extremely large target and isprepared for the application of the extrapolation and interpolation in the spatial domain.

RFD-Rao and RFD-Wald tests for distributed targets with range walking effect

Two novel adaptive distributed target detectors, the range frequency domain-Rao （RFD-Rao） and range frequency domain-Wald （RFD-Wald） tests are proposed in this work. The application methods for these tests consider a partially homogeneous disturbance environment and a target range walking effect in a coherent processing interval （CPI）. The asymptotic performance of the detectors is analyzed, and the constant false alarm rate （CFAR） properties with respect to the clutter covariance matrix and power level are shown. The performances of the proposed adaptive detectors are assessed through Monte-Carlo simulations, and the results are presented to demonstrate the effectiveness of the proposed detection algorithms compared to those of similar existing detectors.

Robust detector for range-spread targets in non-Gaussian background

Based on the target scatterer density, the range-spread target detection of high-resolution radar is addressed in additive non-Gaussian clutter, which is modeled as a spherically invariant random vector. Firstly, for sparse scatterer density, the detection of target scatterer in each range cell is derived, and then an M/K detector is proposed to detect the whole range-spread target. Se- condly, an integrating detector is devised to detect a range-spread target with dense scatterer density. Finally, to make the best of the advantages of M/K detector and integrating detector, a robust detector based on scatterer density （DBSD） is designed, which can reduce the probable collapsing loss or quantization error ef- fectively. Moreover, the density decision factor of DBSD is also determined. The formula of the false alarm probability is derived for DBSD. It is proved that the DBSD ensures a constant false alarm rate property. Furthermore, the computational results indi- cate that the DBSD is robust to different clutter one-lag correlations and target scatterer densities. It is also shown that the DBSD out- performs the existing scatterer-density-dependent detector.

Performance analysis of multi-channel order statistics detector for range-spread target

The problem of two order statistics detection schemes for the detection of a spatially distributed target in white Gaussian noise are studied.When the number of strong scattering cells is known,we first show an optimal detector,which requires many processing channels.The structure of such optimal detector is complex.Therefore,a simpler quasi-optimal detector is then introduced.The quasi-optimal detector,called the strong scattering cells’ number dependent order statistics（SND-OS） detector,takes the form of an average of maximum strong scattering cells with a known number.If the number of strong scattering cells is unknown in real situation,the multi-channel order statistics（MC-OS） detector is used.In each channel,a various number of maximums scattered from target are averaged.Then,the false alarm probability analysis and thresholds sets for each channel are given,following the detection results presented by means of Monte Carlo simulation strategy based on simulated target model and three measured targets.In particular,the theoretical analysis and simulation results highlight that the MC-OS detector can efficiently detect range-spread targets in white Gaussian noise.

较粗空间分辨率影响下FMCW 激光雷达测距方法研究

由于环境中杂散光和电磁干扰等原因,以及不同路径的长度和反射特性的差异,FMCW激光雷达系统在接收目标回波信号时会受到多径干扰的影响,存在噪声干扰,使得目标测距结果准确性较低。为此,提出较粗空间分辨率影响下FMCW激光雷达测距方法。根据FMCWN激光雷达系统的发射信号与回波信号获取中频信号;采用EMD算法分解中频信号,计算信号IMF分量之间的互相关系数,确定并剔除存在噪声的IMF分量;采用SFFT算法对去噪后的中频信号频谱局部细化处理,获取其估计值,确定修正方向,修正频率估计值,利用中频信号修正后的频率确定被测目标的距离。实验结果表明,所提方法具有良好的去噪效果、频谱估计精度、测距精度高,测距效率高,测距均方根误差均在0.04以内,耗时最长仅为0.23 ms。

Analysis of the Flow Field and Impact Force in High-Pressure Water Descaling

This study aims to improve the performances of the high-pressure water descaling technology used in steel hot rolling processes.In particular,a 2050 mm hot rolling line is considered,and the problem is investigated by means of a fluid–structure interaction(FSI)method by which the descaling effect produced by rolling coils with different section sizes is examined.Assuming a flat fan-shaped nozzle at the entrance of the R1R2 roughing mill,the outflow field characteristics and the velocity distribution curve on the strike line(at a target distance of 30–120 mm)are determined.It is found that the velocity in the center region of the water jet with different target distances is higher than that in the boundary region.As the target distance increases,the velocity of the water jet in the central region decreases.Through comparison with experimental results,it is shown that the simulation model can accurately predict the impact position of the high-pressure water on the impact plate,thereby providing a computational scheme that can be used to optimize the nozzle space layout and improve the slabs’descent effect for different rolling specifications.

Ship recognition based on HRRP via multi-scale sparse preserving method

In order to extract the richer feature information of ship targets from sea clutter, and address the high dimensional data problem, a method termed as multi-scale fusion kernel sparse preserving projection(MSFKSPP) based on the maximum margin criterion(MMC) is proposed for recognizing the class of ship targets utilizing the high-resolution range profile(HRRP). Multi-scale fusion is introduced to capture the local and detailed information in small-scale features, and the global and contour information in large-scale features, offering help to extract the edge information from sea clutter and further improving the target recognition accuracy. The proposed method can maximally preserve the multi-scale fusion sparse of data and maximize the class separability in the reduced dimensionality by reproducing kernel Hilbert space. Experimental results on the measured radar data show that the proposed method can effectively extract the features of ship target from sea clutter, further reduce the feature dimensionality, and improve target recognition performance.

Self-sustained target waves in excitable media with only a long-range link

In this paper we investigate spatiotemporal pattern formation in excitable media with only a long-range link. Besides the trivial solutions of spiral patterns, we find the asymptotic self-sustained target waves in the autonomous tissues. The wave source supporting this kind of new pattern is the oscillatory one-dimensional Winfree-loop self- organized under the presence of a long-range link, which is explored by the dominant phase-advanced driving method. Based on this understanding we can effectively regulate the oscillations of excitable media by suitably arranging the long-range link, including construction of self-sustained target waves with controllable period and wave length, or manipulation of system states between different patterns.

基于Prewitt算子和Radon变换的雷达高速微弱目标检测

正交频分复用(OFDM)调制雷达中跨距离单元走动问题降低了高速微弱目标检测性能,为此,提出一种基于Prewitt算子和Radon变换的OFDM雷达高速微弱目标检测算法。首先分析了多脉冲积累出现的跨距离单元走动以及Radon变换受噪声干扰问题,然后采用Prewitt算子卷积运算抑制噪声并保留回波能量,采用Radon变换沿距离单元走动斜线进行能量积累。理论分析和仿真结果表明,该算法具有比Hough变换和动目标检测(MTD)更优的低信噪比背景下的高速微弱目标检测性能,并能有效实现多目标检测。

机载高分辨CSSAR地面加速运动目标成像方法

机载圆轨迹条带合成孔径雷达(circular stripmap synthetic aperture radar,CSSAR)的圆轨迹运动导致目标信号特性复杂、目标距离方程高阶分量显著等问题,给运动目标成像带来很多困难。考虑到高分辨是未来的发展趋势,针对机载高分辨CSSAR,提出一种地面加速运动目标成像方法。首先,针对目标距离方程高阶分量显著的问题,建立了四阶Taylor近似距离模型,以保证成像质量。接着,推导了目标二维频域信号模型,提出通过二维频域相位相乘来高效地实现目标聚焦,并利用差分进化算法高效地实现对距离模型各参数的精确搜索。最后,通过实验验证了所提方法的有效性。

Eigen-Range Profiles for Radar Target Classification

A new millimet er-wave radar target classification approach based on Eigen-Range Profiles is proposed. Comparing with the conventional matching score approach, it has better classification performance, lower storage and computational requirements owing to the reduction of the target class number in data base. The results have verified the validity of this approach.

探讨2型糖尿病患者血糖目标范围内时间与HbA1c变异系数及HVS的关系

目的 探讨2型糖尿病患者血糖目标范围内时间(Time In Range, TIR)与糖化血红蛋白(Glycosylated Hemoglobin A1c, HbA1c)变异系数及糖化血红蛋白变异性评分(HbA1c Variability Score, HVS)的关系。方法 选取2021年1月—2022年1月于泉州市光前医院行动态血糖监测(Continuous Glucose Monitoring, CGM)的82例2型糖尿病患者为研究对象,根据TIR水平分为低TIR组(TIR<85%)30例和高TIR组(TIR≥85%)52例,对所有患者随访观察1年,观察两组随访期间HbA1c变异系数和HVS;使用Spearman分析2型糖尿病患者TIR与HbA1c变异系数及HVS的关系。结果 低TIR组与高TIR组在性别、血压、服用二甲双胍、服用磺胺类药物、年龄、体质指数(Body Mass Index, BMI)、病程、使用胰岛素、空腹血糖(Fasting Plasma Glucose, FPG)、餐后2 h血糖(2 Hour Postprandial Plasma Glucose, 2 hPG)、HbA1c方面比较,差异无统计学意义(P均>0.05)。低TIR组的HbA1c变异系数及HVS均显著高于高TIR组,差异有统计学意义(P均<0.05)。Spearman相关性分析显示,TIR与HbA1c变异系数(r=-0.548,P<0.05)、HVS(r=-0.631,P<0.05)呈负相关。结论 2型糖尿病患者TIR与HbA1c变异系数、HVS呈负相关关系;2型糖尿病患者的TIR越低,其HbA1c变异系数、HVS越高,血糖变异性越明显。

基于ConvLSTM的空间进动锥体目标HRRP序列预测

宽带雷达对空间进动锥体目标进行持续探测能够形成高分辨距离像(high resolution range profile,HRRP)序列。HRRP序列携带空间进动锥体目标的空间几何信息和运动规律等信息,是进行目标关联跟踪和分类识别的重要依据,因此研究空间进动锥体目标的HRRP序列预测具有重要意义。卷积长短时记忆(ConvLSTM)网络将CNN和LSTM二者的特点有效结合,能够充分挖掘HRRP序列的空间和时间特性,完成对HRRP的预测。本文基于空间锥体目标的进动模型建立了多种尺寸、运动速度和运动方向等不同参数的HRRP序列数据集,并利用此数据集根据HRRP特性设计实现了适用于空间进动椎体目标HRRP预测的ConvLSTM网络模型。为了测试本文设计的ConvLSTM网络预测效果,将ConvLSTM网络与二维卷积神经网络模型进行预测效果对比分析。仿真实验结果表明,ConvLSTM网络预测结果与物理光学法计算得到的HRRP一致性高,皮尔逊相关系数高达0.9731,平均绝对误差低至0.0334,相较于二维卷积神经网络预测结果更加准确。证明本文设计的ConvLSTM网络模型能够有效提取HRRP序列的时间和空间特征,实现对HRRP序列的高精度预测。