The aspect sensitivity is the main problem in radar automatic target recognition using high resolution range profile (HRRP). In the traditional viewpoint,HRRPs are assumed to be highly similar if the aspect variation ...The aspect sensitivity is the main problem in radar automatic target recognition using high resolution range profile (HRRP). In the traditional viewpoint,HRRPs are assumed to be highly similar if the aspect variation is not enough to cause range migration. However,some experiments in anechoic chambers don’t agree with the assumption. Particularly,some abnormal HRRPs often occur in the measured data. Based on the scattering center model,this paper focuses on the reason of abnormal HRRP,which is named as the speckle. The theoretical model of speckle is established and the "spurious dual peaks" feature of the speckled HRRP is analyzed. Then the occurrence condition of speckle is concluded,and so is the relationship between the speckle probability in HRRP and radar carrier frequency. At last,the experiment in an anechoic chamber is used to verify all the analyses about the speckle.展开更多
在未发生散射点越距离单元走动(Moving Through Range Cell,MTRC)的角域内,闪烁现象是导致高分辨距离像(High Resolution Range Profile,HRRP)波动的主要原因。该文基于匹配度准则定量分析闪烁时HRRP常用谱特征(幅度谱、功率谱及高阶谱...在未发生散射点越距离单元走动(Moving Through Range Cell,MTRC)的角域内,闪烁现象是导致高分辨距离像(High Resolution Range Profile,HRRP)波动的主要原因。该文基于匹配度准则定量分析闪烁时HRRP常用谱特征(幅度谱、功率谱及高阶谱)的变化规律,比较各种谱特征受闪烁影响的强弱及原因,以获得定量的结论指导谱特征的选择。蒙特卡罗实验和暗室实测数据均表明:闪烁对HRRP谱特征的影响与闪烁散射点在目标能量中所占比重、闪烁区间的远近有关;除此之外,闪烁对高阶谱的影响还与高阶谱的阶数有关;常用谱特征中,功率谱受闪烁的影响最弱。展开更多
Template database is the key to radar automation target recognition based on High Resolution Range Profile (HRRP). From the traditional perspective, average HRRP is a valid template for it can represent each HRRP with...Template database is the key to radar automation target recognition based on High Resolution Range Profile (HRRP). From the traditional perspective, average HRRP is a valid template for it can represent each HRRP without scatterer Moving Through Range Cell (MTRC). However, template database based on this assumption is always challenged by measured data. One reason is that speckle happens in the frame without scatterer MTRC. Speckle makes HRRP fluctuate sharply and not match well with the average HRRP. We precisely introduce the formation mechanism of speckle. Then, we make an insight into the principle of matching score. Based on the conclusion, we study the properties of matching score between speckled HRRP and the average HRRP. The theoretical analysis and Monte Carlo experimental results demonstrate that speckle makes HRRP not to match well with the average HRRP according to the energy ratio of speckled scatterers. On the assumption of ideal scattering centre model, speckled HRRP has a matching score less than 85% with the average HRRP if speckled scatterers occupy more than 50% energy of the target.展开更多
The relationship between stiffness distribution and aeroelastic performance for a beam-frame model and a3-D model is investigated based on aeroelastic optimization of global stiffness design for high-aspect-ratio wing...The relationship between stiffness distribution and aeroelastic performance for a beam-frame model and a3-D model is investigated based on aeroelastic optimization of global stiffness design for high-aspect-ratio wings.The sensitivity information of wing spanwise stiffness distribution with respect to the twist angle at wing tip,the vertical displacement at wing tip,and the flutter speed are obtained using a sensitivity method for both models.Then the relationship between stiffness distribution and aeroelastic performance is summarized to guide the design procedure.By using the genetic/sensitivity-based hybrid algorithm,an optimal solution satisfying the strength,aeroelastic and manufacturing constraints is obtained.It is found that the summarized guidance is well consistent with the optimal solution,thus providing a valuable design advice with efficiency.The study also shows that the aeroelastic-optimization-based global stiffness design procedure can obtain the optimal solution under multiple constraints with high efficiency and precision,thereby having a strong application value in engineering.展开更多
太赫兹由于其穿透性强、大带宽等优势,在雷达信号处理领域受到了广泛的关注。同时,高分辨率距离像(High Resolution Range Profiles,HRRP)在目标检测、识别以及成像等领域具有很高的应用价值,但是,针对太赫兹频段目标HRRP特性的研究却...太赫兹由于其穿透性强、大带宽等优势,在雷达信号处理领域受到了广泛的关注。同时,高分辨率距离像(High Resolution Range Profiles,HRRP)在目标检测、识别以及成像等领域具有很高的应用价值,但是,针对太赫兹频段目标HRRP特性的研究却较少。本文首先从确定信号模型对太赫兹频段目标HRRP的方位角敏感性进行了研究,并利用协方差矩阵的主特征向量提取其平均HRRP,从而达到抑制目标HRRP方位角敏感性的目的。另外,根据距离单元中散射点的不同分布,对太赫兹雷达目标HRRP距离单元进行分类,并分别使用瑞利模型、赖斯模型以及混合分布模型进行统计建模。之后,使用对数积累量方法(Method of Log-Cumulants,Mo LC)和基于字典的随机最大期望(Dictionary-based Stochastic Expectation-Maximization,DSEM)算法对上述模型的参数进行估计。最后,利用研制的太赫兹高分辨率雷达系统开展了不同带宽下的复杂目标HRRP特性实验,实验结果表明,太赫兹频段下目标平均HRRP与HRRP帧内其他HRRP的相关系数高于单个HRRP,同时,对于高分辨率下的目标HRRP距离单元统计特性,可以使用混合分布模型对其进行建模。展开更多
文摘The aspect sensitivity is the main problem in radar automatic target recognition using high resolution range profile (HRRP). In the traditional viewpoint,HRRPs are assumed to be highly similar if the aspect variation is not enough to cause range migration. However,some experiments in anechoic chambers don’t agree with the assumption. Particularly,some abnormal HRRPs often occur in the measured data. Based on the scattering center model,this paper focuses on the reason of abnormal HRRP,which is named as the speckle. The theoretical model of speckle is established and the "spurious dual peaks" feature of the speckled HRRP is analyzed. Then the occurrence condition of speckle is concluded,and so is the relationship between the speckle probability in HRRP and radar carrier frequency. At last,the experiment in an anechoic chamber is used to verify all the analyses about the speckle.
文摘在未发生散射点越距离单元走动(Moving Through Range Cell,MTRC)的角域内,闪烁现象是导致高分辨距离像(High Resolution Range Profile,HRRP)波动的主要原因。该文基于匹配度准则定量分析闪烁时HRRP常用谱特征(幅度谱、功率谱及高阶谱)的变化规律,比较各种谱特征受闪烁影响的强弱及原因,以获得定量的结论指导谱特征的选择。蒙特卡罗实验和暗室实测数据均表明:闪烁对HRRP谱特征的影响与闪烁散射点在目标能量中所占比重、闪烁区间的远近有关;除此之外,闪烁对高阶谱的影响还与高阶谱的阶数有关;常用谱特征中,功率谱受闪烁的影响最弱。
文摘Template database is the key to radar automation target recognition based on High Resolution Range Profile (HRRP). From the traditional perspective, average HRRP is a valid template for it can represent each HRRP without scatterer Moving Through Range Cell (MTRC). However, template database based on this assumption is always challenged by measured data. One reason is that speckle happens in the frame without scatterer MTRC. Speckle makes HRRP fluctuate sharply and not match well with the average HRRP. We precisely introduce the formation mechanism of speckle. Then, we make an insight into the principle of matching score. Based on the conclusion, we study the properties of matching score between speckled HRRP and the average HRRP. The theoretical analysis and Monte Carlo experimental results demonstrate that speckle makes HRRP not to match well with the average HRRP according to the energy ratio of speckled scatterers. On the assumption of ideal scattering centre model, speckled HRRP has a matching score less than 85% with the average HRRP if speckled scatterers occupy more than 50% energy of the target.
基金supported by the National Natural Science Foundation of China (Nos.11302011,11372023, 11172025)
文摘The relationship between stiffness distribution and aeroelastic performance for a beam-frame model and a3-D model is investigated based on aeroelastic optimization of global stiffness design for high-aspect-ratio wings.The sensitivity information of wing spanwise stiffness distribution with respect to the twist angle at wing tip,the vertical displacement at wing tip,and the flutter speed are obtained using a sensitivity method for both models.Then the relationship between stiffness distribution and aeroelastic performance is summarized to guide the design procedure.By using the genetic/sensitivity-based hybrid algorithm,an optimal solution satisfying the strength,aeroelastic and manufacturing constraints is obtained.It is found that the summarized guidance is well consistent with the optimal solution,thus providing a valuable design advice with efficiency.The study also shows that the aeroelastic-optimization-based global stiffness design procedure can obtain the optimal solution under multiple constraints with high efficiency and precision,thereby having a strong application value in engineering.
文摘太赫兹由于其穿透性强、大带宽等优势,在雷达信号处理领域受到了广泛的关注。同时,高分辨率距离像(High Resolution Range Profiles,HRRP)在目标检测、识别以及成像等领域具有很高的应用价值,但是,针对太赫兹频段目标HRRP特性的研究却较少。本文首先从确定信号模型对太赫兹频段目标HRRP的方位角敏感性进行了研究,并利用协方差矩阵的主特征向量提取其平均HRRP,从而达到抑制目标HRRP方位角敏感性的目的。另外,根据距离单元中散射点的不同分布,对太赫兹雷达目标HRRP距离单元进行分类,并分别使用瑞利模型、赖斯模型以及混合分布模型进行统计建模。之后,使用对数积累量方法(Method of Log-Cumulants,Mo LC)和基于字典的随机最大期望(Dictionary-based Stochastic Expectation-Maximization,DSEM)算法对上述模型的参数进行估计。最后,利用研制的太赫兹高分辨率雷达系统开展了不同带宽下的复杂目标HRRP特性实验,实验结果表明,太赫兹频段下目标平均HRRP与HRRP帧内其他HRRP的相关系数高于单个HRRP,同时,对于高分辨率下的目标HRRP距离单元统计特性,可以使用混合分布模型对其进行建模。
