In this study, we explore the far-zero behaviors of a scattered partially polarized spatially and spectrally partially coherent electromagnetic pulsed beam irradiating on a deterministic medium. The analytical formula...In this study, we explore the far-zero behaviors of a scattered partially polarized spatially and spectrally partially coherent electromagnetic pulsed beam irradiating on a deterministic medium. The analytical formula for the cross-spectral density matrix elements of this beam in the spherical coordinate system is derived. Within the framework of the first-order Born approximation, the effects of the scattering angle θ, the source parameters (i.e., the pulse duration T0 and the temporal coherence length Tcxx), and the scatterer parameter (i.e., the effective width of the medium σR) on the spectral density, the spectral shift, the spectral degree of polarization, and the degree of spectral coherence of the scattered source in the far-zero field are studied numerically and comparatively. Our work improves the scattering theory of stochastic electromagnetic beams and it may be useful for the applications involving the interaction between incident light waves and scattering media.展开更多
Soil organic matter(SOM) is an important parameter related to soil nutrient and miscellaneous ecosystem services. This paper attempts to improve the performance of traditional partial least square regression(PLSR) mod...Soil organic matter(SOM) is an important parameter related to soil nutrient and miscellaneous ecosystem services. This paper attempts to improve the performance of traditional partial least square regression(PLSR) model by considering the spatial autocorrelation and soil forming factors. Surface soil samples(n = 180) were collected from Honghu City located in the middle of Jianghan Plain, China. The visible and near infrared(VNIR) spectra and six environmental factors(elevation, land use types, roughness, relief amplitude, enhanced vegetation index, and land surface water index) were used as the auxiliary variables to construct the multiple linear regression(MLR), PLSR and geographically weighted regression(GWR) models. Results showed that: 1) the VNIR spectra can increase about 39.62% prediction accuracy than the environmental factors in predicting SOM; 2) the comprehensive variables of VNIR spectra and the environmental factors can improve about 5.78% and 44.90% relative to soil spectral models and soil environmental models, respectively; 3) the spatial model(GWR) can improve about 3.28% accuracy than MLR and PLSR. Our results suggest that the combination of spectral reflectance and the environmental variables can be used as the suitable auxiliary variables in predicting SOM, and GWR is a promising model for predicting soil properties.展开更多
在实际测向系统中,当弱信号和强干扰空间临近时,空间谱测向系统仅能对强干扰进行波达方向(Direction of Arrival,DOA)估计,弱信号DOA估计性能下降甚至失效。针对这一问题,研究了空间谱扩展噪声子空间算法结合通道幅相误差校正,在强干扰...在实际测向系统中,当弱信号和强干扰空间临近时,空间谱测向系统仅能对强干扰进行波达方向(Direction of Arrival,DOA)估计,弱信号DOA估计性能下降甚至失效。针对这一问题,研究了空间谱扩展噪声子空间算法结合通道幅相误差校正,在强干扰抑制条件下对弱信号进行DOA估计的方法。该方法对采样信号的噪声协方差进行去加权处理,并对空间谱扩展噪声子空间算法的空间谱导向矢量进行修正。基于通用软件无线电外设(Universal SoftwareRadioPeripheral,USRP)和印刷偶极子线形天线阵构建实验平台,实验结果证明空间谱扩展噪声子空间算法结合改进的通道幅相误差校正方法,能对临近干扰源进行空间谱抑制的同时,实现对弱信号的DOA估计。展开更多
针对高光谱遥感图像复杂农作物分类问题,提出了一种基于空谱融合和随机多图的高光谱遥感图像农作物分类方法。通过使用一种潜在特征融合和最优聚类(Latent Features Fusion and Optimal Clustering Framework,LFFOCF)的波段选择方法和...针对高光谱遥感图像复杂农作物分类问题,提出了一种基于空谱融合和随机多图的高光谱遥感图像农作物分类方法。通过使用一种潜在特征融合和最优聚类(Latent Features Fusion and Optimal Clustering Framework,LFFOCF)的波段选择方法和分段主成分分析(Segmented Principal Component Analysis,SPCA)进行光谱降维,采用多尺度二维奇异谱分析(2-D-Singular Spectrum Analysis,2-D-SSA)应用于降维图像,以提取不同尺度的空间特征。将多尺度空间特征与主成分分析(Principal Component Analysis,PCA)得到的全局光谱特征融合送到随机多图(Random Multi-Graphs,RMG)中进行分类。在印度松树、萨利纳斯和龙口数据集上,所提出的方法与一些现有的方法进行了对比实验。实验结果表明,该方法的类别精度(Class Accuracy,CA)、总体分类精度(Overall Accuracy,OA)、平均分类精度(Average Accuracy,AA)和Kappa系数优于这些方法。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 11504286)the Natural Science Basic Research Program of Shaanxi Province, China (Grant No. 2019JM-470)+1 种基金the Fund from the International Technology Collaborative Center for Advanced Optical Manufacturing and Optoelectronic Measurementthe Science Fund from the Shaanxi Provincial Key Laboratory of Photoelectric Measurement and Instrument Technology.
文摘In this study, we explore the far-zero behaviors of a scattered partially polarized spatially and spectrally partially coherent electromagnetic pulsed beam irradiating on a deterministic medium. The analytical formula for the cross-spectral density matrix elements of this beam in the spherical coordinate system is derived. Within the framework of the first-order Born approximation, the effects of the scattering angle θ, the source parameters (i.e., the pulse duration T0 and the temporal coherence length Tcxx), and the scatterer parameter (i.e., the effective width of the medium σR) on the spectral density, the spectral shift, the spectral degree of polarization, and the degree of spectral coherence of the scattered source in the far-zero field are studied numerically and comparatively. Our work improves the scattering theory of stochastic electromagnetic beams and it may be useful for the applications involving the interaction between incident light waves and scattering media.
基金Under the auspices of the Natural Science Foundation of Hubei(No.2018CFB372)the Fundamental Research Funds for the Central Universities(No.2662016QD032)+2 种基金the Key Laboratory of Aquatic Plants and Watershed Ecology of Chinese Academy of Sciences(No.Y852721s04)the Chinese National Natural Science Foundation(No.41371227)the National Undergraduate Innovation and Entrepreneurship Training Program(No.201810504023,201810504030)
文摘Soil organic matter(SOM) is an important parameter related to soil nutrient and miscellaneous ecosystem services. This paper attempts to improve the performance of traditional partial least square regression(PLSR) model by considering the spatial autocorrelation and soil forming factors. Surface soil samples(n = 180) were collected from Honghu City located in the middle of Jianghan Plain, China. The visible and near infrared(VNIR) spectra and six environmental factors(elevation, land use types, roughness, relief amplitude, enhanced vegetation index, and land surface water index) were used as the auxiliary variables to construct the multiple linear regression(MLR), PLSR and geographically weighted regression(GWR) models. Results showed that: 1) the VNIR spectra can increase about 39.62% prediction accuracy than the environmental factors in predicting SOM; 2) the comprehensive variables of VNIR spectra and the environmental factors can improve about 5.78% and 44.90% relative to soil spectral models and soil environmental models, respectively; 3) the spatial model(GWR) can improve about 3.28% accuracy than MLR and PLSR. Our results suggest that the combination of spectral reflectance and the environmental variables can be used as the suitable auxiliary variables in predicting SOM, and GWR is a promising model for predicting soil properties.
文摘在实际测向系统中,当弱信号和强干扰空间临近时,空间谱测向系统仅能对强干扰进行波达方向(Direction of Arrival,DOA)估计,弱信号DOA估计性能下降甚至失效。针对这一问题,研究了空间谱扩展噪声子空间算法结合通道幅相误差校正,在强干扰抑制条件下对弱信号进行DOA估计的方法。该方法对采样信号的噪声协方差进行去加权处理,并对空间谱扩展噪声子空间算法的空间谱导向矢量进行修正。基于通用软件无线电外设(Universal SoftwareRadioPeripheral,USRP)和印刷偶极子线形天线阵构建实验平台,实验结果证明空间谱扩展噪声子空间算法结合改进的通道幅相误差校正方法,能对临近干扰源进行空间谱抑制的同时,实现对弱信号的DOA估计。
