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Science Bulletin 2016年第24期61卷 1844-1854页

作者： Yang Hu Jijun Wang Chunbo Li Yin-Shan Wang Zhi Yang Xi-Nian Zuo Key Laboratory of Behavioral Science Laboratory for HumanConnectome and Development Magnetic Resonance ResearchCenter Institute of Psychology Chinese Academy of SciencesBeijing 100101 China University of Chinese Academy of Sciences Beijing 100049China Shanghai Key Laboratory of Psychotic Disorders Shanghai Mental Health Center Shanghai Jiao Tong University School of Medicine Shanghai 200030 China

Abstract A brain network consisting of two key parietal nodes, the precuneus and the posterior cingulate cortex, has emerged from recent fMRI studies. Though it is anatomically adjacent to and spatially overlaps with the default mode network （DMN）, its function has been associated with memory processing, and it has been referred to as the parietal memory network （PMN）. Independent component analysis （ICA） is the most common data-driven method used to extract PMN and DMN simultaneously. However, the effects of data preprocessing and parameter determi- nation in ICA on PMN-DMN segregation are completely unknown. Here, we employ three typical algorithms of group ICA to assess how spatial smoothing and model order influence the degree of PMN-DMN segregation. Our findings indicate that PMN and DMN can only be stably separated using a combination of low-level spatial smoothing and high model order across the three ICA algorithms. We thus argue for more considerations on parametric settings for interpreting DMN data.

关键词： Default mode network Parietal memory network Independent component analysis Model order Resting-state fMRI spatial smoothing

New targets number estimation method under colored noise background

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Journal of Systems Engineering and Electronics 2012年第6期23卷 831-837页

作者： Jing Wang Jianguo Huang Jing Han Zhenhua Xu College of Marine Engineering Northwestern Polytechnical University Xi'an 710072 E R. China

A multiple targets detection method based on spatial smoothing （MTDSS） is proposed to solve the problem of the source number estimation under the colored noise background. The forward and backward smoothing based on auxiliary vectors which are received data on some specific elements is computed. By the spatial smoothing with auxiliary vectors, the correlated signals are decorrelated, and the colored noise is partially alleviated. The correlation matrix formed from the cross correlations between subarray data and auxiliary vectors is computed. By exploring the second-order statistics property of the covariance matrix, a threshold based on Gerschgorin radii of the smoothing correlation matrix is set to estimate the number of sources. Simulations and experimental results validate that MTDSS has an effective performance under the condition of the colored noise background and coherent sources, and MTDSS is robust with the correlated factor of signals and noise.

关键词： colored noise auxiliary vector multiple targets detec-tion spatial smoothing Gerschgorin radii.

spatially smoothed quaternion-Capon beamforming in the presence of coherent interferences

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Journal of Beijing Institute of Technology 2016年第2期25卷 225-230页

作者：刘志文王亚昕章希睿徐友根 School of Information and Electronics Beijing Institute of Technology

The performance the quaternion-Capon（ Q-Capon） beamformer degraded when suppressing the interferences that are coherent with the signal of interest（ SOI）. To tackle the problem,the spatial smoothing technique is adopted in quaternion domain to decorrelate the interferences by using linearly and uniformly spaced two-component electromagnetic vector-sensors. By averaging several translational invariant subarray quaternion covariance matrices,the quaternion spatial smoothing is performed to prevent the SOI cancellation phenomena caused by the presence of coherent interferences. It is demonstrated that the quaternion spatial smoothing Q-Capon beamformer can suppress the coherent interferences remarkably while the computational cost is lower than the complex domain long vector spatial smoothing counterpart. Theoretical analyses and simulation results validate the efficacy of the spatially smoothed Q-Capon beamformer in terms of coherent interference suppression capability.

关键词： adaptive beamforming electromagnetic vector-sensor array spatial smoothing quaternion

Inferring seismic hazard in Sichuan-Yunnan region of China based on the modern earthquake catalogue (1980-2019)

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Earthquake Science 2020年第3期33卷 107-115页

作者： Ziyao Xiong Shiyong Zhou Jiancang Zhuang School of Earth and Space Sciences Peking UniversityBeijing100871China The Institute of Statistical Mathematics Tokyo 1908562Japan

Based on the modern earthquake catalogue,the incomplete centroidal voronoi tessellation(ICVT)method was used in this study to estimate the seismic hazard in Sichuan-Yunnan region of *** calculated spatial distributions of the total seismic hazard and background seismic hazard in this *** Bayesian delaunay tessellation smoothing method put forward by Ogata was used to calculate the spatial distributions of *** results show that seismic hazards in Sichuan-Yunan region are high,and areas with relatively high hazard values are distributed along the main faults,while seismic hazards in Sichuan basin are relatively low.

关键词： seismic hazard analysis Voronoi tessellation spatial smoothing b-value

Multipath Time Delay Estimation Based on MUSIC Algorithm Under Small Sample Conditions

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Instrumentation 2022年第4期9卷 58-66页

作者： CHEN Meng XING Hongyan WANG Haifeng WU Yeli School of Electronic and Information Engineering Nanjing University of Information Science and TechnologyNanjing 210044China

On account of the traditional multiple signal classification(MUSIC)algorithm has poor performance in time delay estimation under the condition of small sampling data and low *** this paper,the traditional MUSIC algorithm is *** algorithm combines the idea of spatial smoothing,constructs a new covariance matrix using the covariance information of the measurement data,and constructs a weighted value using the modified noise eigenvalues to weight the traditional estimation *** results show that the improved algorithm has steeper spectral peaks and better time delay resolution under the condition of inaccurate path number *** time delay estimation accuracy of this algorithm is higher than that of the traditional MUSIC algorithm and the improved SSMUSIC algorithm under the conditions of small sampling data and low SNR.

关键词： Multipath Time Delay Estimation MUSIC Algorithm spatial smoothing