This paper focuses on the adaptive detection of range and Doppler dual-spread targets in non-homogeneous and nonGaussian sea clutter.The sea clutter from two polarimetric channels is modeled as a compound-Gaussian mod...This paper focuses on the adaptive detection of range and Doppler dual-spread targets in non-homogeneous and nonGaussian sea clutter.The sea clutter from two polarimetric channels is modeled as a compound-Gaussian model with different parameters,and the target is modeled as a subspace rangespread target model.The persymmetric structure is used to model the clutter covariance matrix,in order to reduce the reliance on secondary data of the designed detectors.Three adaptive polarimetric persymmetric detectors are designed based on the generalized likelihood ratio test(GLRT),Rao test,and Wald test.All the proposed detectors have constant falsealarm rate property with respect to the clutter texture,the speckle covariance matrix.Experimental results on simulated and measured data show that three adaptive detectors outperform the competitors in different clutter environments,and the proposed GLRT detector has the best detection performance under different parameters.展开更多
The problem of adaptive radar detection in compound-Gaussian clutter without secondary data is considered in this paper.In most practical applications,the number of training data is limited.To overcome the lack of tra...The problem of adaptive radar detection in compound-Gaussian clutter without secondary data is considered in this paper.In most practical applications,the number of training data is limited.To overcome the lack of training data,an autoregressive(AR)-process-based covariance matrix estimator is proposed.Then,with the estimated covariance matrix the one-step generalized likelihood ratio test(GLRT)detector is designed without training data.Finally,detection performance of our proposed detector is assessed.展开更多
针对柴油发动机推进特性下的中高负荷工况出现的NO_(x)排放峰值现象,以及燃油价格日益上涨带来降低油耗率的迫切需求,本研究通过调节柴油/甲醇组合燃烧(diesel/methanol compound combustion,DMCC)发动机多种控制参数,在保证动力性前提...针对柴油发动机推进特性下的中高负荷工况出现的NO_(x)排放峰值现象,以及燃油价格日益上涨带来降低油耗率的迫切需求,本研究通过调节柴油/甲醇组合燃烧(diesel/methanol compound combustion,DMCC)发动机多种控制参数,在保证动力性前提下,实现NO_(x)排放和有效燃油消耗率(brake specific fuel consumption,BSFC)的同步下降。为避免大规模试验带来的成本增加,首先基于高斯过程回归建立DMCC发动机排放的NO_(x)体积分数、BSFC和指示功率预测模型;然后将所建模型与第二代非支配排序遗传算法(non-dominated sorting genetic algorithm-Ⅱ,NSGA-Ⅱ)结合,对NO_(x)的体积分数和BSFC进行优化,并将Pareto前沿解集代入逼近理想解排序法(the technique for order preference by similarity to an ideal solution,TOPSIS)寻找最优控制参数组合;最后将最优控制参数组合标定至电子控制单元,与原机数据进行对比分析。结果表明:基于高斯过程回归建立的预测模型的拟合优度大于0.95,均方根误差小于1,具有良好的一致性和准确性;使用NSGA-Ⅱ获取的最佳控制参数与优化前(原机工况)的相比,NO_(x)的排放量下降74.5%,仅为3.47 g/(kW·h),BSFC平均下降6.7%,仅为203.5 g/(kW·h)。展开更多
该文在复合高斯海杂波背景下,以逆Gamma分布作为纹理分量的先验分布模型,研究了1阶高斯(First Order Gaussian,FOG)和2阶高斯(Second Order Gaussian,SOG)两类子空间目标的自适应检测问题。采用两步广义似然比(Generalized Likelihood R...该文在复合高斯海杂波背景下,以逆Gamma分布作为纹理分量的先验分布模型,研究了1阶高斯(First Order Gaussian,FOG)和2阶高斯(Second Order Gaussian,SOG)两类子空间目标的自适应检测问题。采用两步广义似然比(Generalized Likelihood Ratio Test,GLRT)推导了检测统计量,并分别采用采样协方差矩阵(Sample Covariance Matrix,SCM)、归一化采样协方差矩阵(Normalized Sample Covariance Matrix,NSCM)和定点估计(Function Point Estimation,FPE)作为协方差矩阵估计值,与GLRT相结合,构造出新的自适应检测器。由于该文检测器在设计阶段考虑了海杂波的先验分布模型,且在检测阶段采用了与工作环境相匹配的模型参数,经性能分析与验证,其在检测性能上优于已有匹配滤波(Adaptive Matched Filter,AMF)和归一化匹配滤波(Adaptive Normalized Matched Filter,ANMF)检测器。展开更多
广义似然比检测(Generalized Likelihood Ratio Test,GLRT)是解决复合高斯杂波下扩展目标检测问题的一种有效方法,而当目标速度未知时,经典的GLRT失效。该文针对目标速度未知的情形,提出了一种基于广义特征值分解的扩展目标多普勒频率...广义似然比检测(Generalized Likelihood Ratio Test,GLRT)是解决复合高斯杂波下扩展目标检测问题的一种有效方法,而当目标速度未知时,经典的GLRT失效。该文针对目标速度未知的情形,提出了一种基于广义特征值分解的扩展目标多普勒频率估计算法,可有效估计多普勒频率,并以此为基础设计了一种R-GLRT(Robust GLRT)检测器。仿真结果表明了这种检测器的有效性。展开更多
基金supported by the National Natural Science Foundation of China(62371382,62071346)the Science,Technology&Innovation Project of Xiong’an New Area(2022XAGG0181)the Special Funds for Creative Research(2022C61540)。
文摘This paper focuses on the adaptive detection of range and Doppler dual-spread targets in non-homogeneous and nonGaussian sea clutter.The sea clutter from two polarimetric channels is modeled as a compound-Gaussian model with different parameters,and the target is modeled as a subspace rangespread target model.The persymmetric structure is used to model the clutter covariance matrix,in order to reduce the reliance on secondary data of the designed detectors.Three adaptive polarimetric persymmetric detectors are designed based on the generalized likelihood ratio test(GLRT),Rao test,and Wald test.All the proposed detectors have constant falsealarm rate property with respect to the clutter texture,the speckle covariance matrix.Experimental results on simulated and measured data show that three adaptive detectors outperform the competitors in different clutter environments,and the proposed GLRT detector has the best detection performance under different parameters.
基金supported by the Fundamental Research Funds for the Central Universities under Grant No.E022050205
文摘The problem of adaptive radar detection in compound-Gaussian clutter without secondary data is considered in this paper.In most practical applications,the number of training data is limited.To overcome the lack of training data,an autoregressive(AR)-process-based covariance matrix estimator is proposed.Then,with the estimated covariance matrix the one-step generalized likelihood ratio test(GLRT)detector is designed without training data.Finally,detection performance of our proposed detector is assessed.
文摘为确保柴油/甲醇双燃料燃烧(Diesel/Methanol Compound Combustion,DMCC)发动机在稳定运行的前提下,突破爆震等因素的限制,进一步拓宽甲醇替代率边界,实现发动机性能的进一步提升。首先,在额定转速中高负荷下,分析了废气再循环(Exhaust Gas Recirculation, EGR)对DMCC发动机燃烧稳定性的影响。随后,基于仿真实验数据,建立用于预测燃烧稳定性参数的高斯过程回归(Gaussian Process Regression, GPR)模型。最后,以燃烧稳定性参数为限制条件,绘制拓宽后的甲醇替代率边界图。研究结果表明:EGR技术可显著提升高负荷下的燃烧稳定性,当EGR率从0%提升至20%,90%负荷下的最大压力升高率下降0.08MPa/°CA,爆发压力下降1.12 MPa,在80%~100%负荷区间内,甲醇替代率边界平均拓宽7.81%,特别是100%负荷下,从15.30%拓宽至20.02%。
文摘针对柴油发动机推进特性下的中高负荷工况出现的NO_(x)排放峰值现象,以及燃油价格日益上涨带来降低油耗率的迫切需求,本研究通过调节柴油/甲醇组合燃烧(diesel/methanol compound combustion,DMCC)发动机多种控制参数,在保证动力性前提下,实现NO_(x)排放和有效燃油消耗率(brake specific fuel consumption,BSFC)的同步下降。为避免大规模试验带来的成本增加,首先基于高斯过程回归建立DMCC发动机排放的NO_(x)体积分数、BSFC和指示功率预测模型;然后将所建模型与第二代非支配排序遗传算法(non-dominated sorting genetic algorithm-Ⅱ,NSGA-Ⅱ)结合,对NO_(x)的体积分数和BSFC进行优化,并将Pareto前沿解集代入逼近理想解排序法(the technique for order preference by similarity to an ideal solution,TOPSIS)寻找最优控制参数组合;最后将最优控制参数组合标定至电子控制单元,与原机数据进行对比分析。结果表明:基于高斯过程回归建立的预测模型的拟合优度大于0.95,均方根误差小于1,具有良好的一致性和准确性;使用NSGA-Ⅱ获取的最佳控制参数与优化前(原机工况)的相比,NO_(x)的排放量下降74.5%,仅为3.47 g/(kW·h),BSFC平均下降6.7%,仅为203.5 g/(kW·h)。
文摘该文在复合高斯海杂波背景下,以逆Gamma分布作为纹理分量的先验分布模型,研究了1阶高斯(First Order Gaussian,FOG)和2阶高斯(Second Order Gaussian,SOG)两类子空间目标的自适应检测问题。采用两步广义似然比(Generalized Likelihood Ratio Test,GLRT)推导了检测统计量,并分别采用采样协方差矩阵(Sample Covariance Matrix,SCM)、归一化采样协方差矩阵(Normalized Sample Covariance Matrix,NSCM)和定点估计(Function Point Estimation,FPE)作为协方差矩阵估计值,与GLRT相结合,构造出新的自适应检测器。由于该文检测器在设计阶段考虑了海杂波的先验分布模型,且在检测阶段采用了与工作环境相匹配的模型参数,经性能分析与验证,其在检测性能上优于已有匹配滤波(Adaptive Matched Filter,AMF)和归一化匹配滤波(Adaptive Normalized Matched Filter,ANMF)检测器。
文摘广义似然比检测(Generalized Likelihood Ratio Test,GLRT)是解决复合高斯杂波下扩展目标检测问题的一种有效方法,而当目标速度未知时,经典的GLRT失效。该文针对目标速度未知的情形,提出了一种基于广义特征值分解的扩展目标多普勒频率估计算法,可有效估计多普勒频率,并以此为基础设计了一种R-GLRT(Robust GLRT)检测器。仿真结果表明了这种检测器的有效性。
