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磁化分层等离子体中电磁波传播特性研究 被引量:3
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作者 李慧 刘江凡 +3 位作者 焦子涵 白光辉 高峰 席晓莉 《强激光与粒子束》 EI CAS CSCD 北大核心 2018年第11期74-79,共6页
采用混合矩阵法,分析了磁化分层等离子鞘套对斜入射电磁波传播特性的影响,分别计算了不同入射角以及外加磁场下电磁波透射系数和极化特性的变化。以GPS导航信号右旋圆极化波(RCP)为例,研究了磁场、电子密度对电磁波右旋圆极化特性的影... 采用混合矩阵法,分析了磁化分层等离子鞘套对斜入射电磁波传播特性的影响,分别计算了不同入射角以及外加磁场下电磁波透射系数和极化特性的变化。以GPS导航信号右旋圆极化波(RCP)为例,研究了磁场、电子密度对电磁波右旋圆极化特性的影响。结果表明,外加磁场能够使右旋圆极化波在等离子体中的阻带向高频方向移动,此外,外加磁场能在一定程度上改善斜入射是圆极化波的极化特性,有利于GPS信号接收。 展开更多
关键词 磁化等离子体 混合矩阵方法 极化特性 透射系数
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Underdetermined Blind Source Separation of Adjacent Satellite Interference Based on Sparseness 被引量:10
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作者 Chengjie Li Lidong Zhu Zhongqiang Luo 《China Communications》 SCIE CSCD 2017年第4期140-149,共10页
The problem of underdetermined blind source separation of adjacent satellite interference is proposed in this paper. Density Clustering algorithm(DC-algorithm) presented in this article is different from traditional m... The problem of underdetermined blind source separation of adjacent satellite interference is proposed in this paper. Density Clustering algorithm(DC-algorithm) presented in this article is different from traditional methods. Sparseness representation has been applied in underdetermined blind signal source separation. However, some difficulties have not been considered, such as the number of sources is unknown or the mixed matrix is ill-conditioned. In order to find out the number of the mixed signals, Short Time Fourier Transform(STFT) is employed to segment received mixtures. Then, we formulate the blind source signal as cluster problem. Furthermore, we construct Cost Function Pair and Decision Coordinate System by using density clustering. At the end of this paper, we discuss the performance of the proposed method and verify the novel method based on several simulations. We verify the proposed method on numerical experiments with real signal transmission, which demonstrates the validity of the proposed method. 展开更多
关键词 adjacent satellite interference Short Time Fourier Transform Decision Coordinate System real signal transmission
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Mixing matrix estimation of underdetermined blind source separation based on the linear aggregation characteristic of observation signals
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作者 温江涛 Zhao Qianyun Sun Jiedi 《High Technology Letters》 EI CAS 2016年第1期82-89,共8页
Under the underdetermined blind sources separation(UBSS) circumstance,it is difficult to estimate the mixing matrix with high-precision because of unknown sparsity of signals.The mixing matrix estimation is proposed b... Under the underdetermined blind sources separation(UBSS) circumstance,it is difficult to estimate the mixing matrix with high-precision because of unknown sparsity of signals.The mixing matrix estimation is proposed based on linear aggregation degree of signal scatter plot without knowing sparsity,and the linear aggregation degree evaluation of observed signals is presented which obeys generalized Gaussian distribution(GGD).Both the GGD shape parameter and the signals' correlation features affect the observation signals sparsity and further affected the directionality of time-frequency scatter plot.So a new mixing matrix estimation method is proposed for different sparsity degrees,which especially focuses on unclear directionality of scatter plot and weak linear aggregation degree.Firstly,the direction of coefficient scatter plot by time-frequency transform is improved and then the single source coefficients in the case of weak linear clustering is processed finally the improved K-means clustering is applied to achieve the estimation of mixing matrix.The proposed algorithm reduces the requirements of signals sparsity and independence,and the mixing matrix can be estimated with high accuracy.The simulation results show the feasibility and effectiveness of the algorithm. 展开更多
关键词 underdetermined blind source separation (UBSS) sparse component analysis(SCA) mixing matrix estimation generalized Gaussian distribution (GGD) linear aggregation
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