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Near field imaging of small isotropic and extended anisotropic scatterers

APPLICABLE ANALYSIS 2017年第10期96卷 1713-1736页

作者： Harris, I. Rome, S. Texas A&M Univ Dept Math College Stn TX 77843 USA

In this paper, we consider two time-harmonic inverse scattering problems of reconstructing penetrable inhomogeneous obstacles from near field measurements. First, we appeal to the Born approximation for reconstructing small isotropic scatterers via the music algorithm. Some numerical reconstructions using the music algorithm are provided for reconstructing the scatterer and piecewise constant refractive index using a Bayesian method. We then consider the reconstruction of an anisotropic extended scatterer by a modified linear sampling method and the factorization method applied to the near field operator. This provides a rigorous characterization of the support of the anisotropic obstacle in terms of a range test derived from the measured data. Under appropriate assumptions on the material parameters, the derived factorization can be used to determine the support of the medium without a priori knowledge of the material properties.

关键词： Inverse scattering music algorithm factorization method near field operator

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Application of the DOA algorithms in the Uniform Circular Array Antennas

Application of the DOA Algorithms in the Uniform Circular Ar...

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作者： Sun Cuizhen Ding Jun School of Electronics and Information Northwestern Polytechnical University Xi'an University of Science and Technology

The conventional DOA(Direction of Arrival)estimation methods of the uniform circular array antennas use the technology of beam scanning which needs a lot of array *** the finite array DOA estimation,the resolution ratio is affected by the Rayleigh ***,the music algorithm can solve this problem,it fully utilizes the orthogonality of noise subspace and signal *** the algorithm constructs the spatial spectrum function,it can achieve the DOA estimation through the spectrum peak *** on the uniform circular array antennas,the Bartlett beamforming method,the Capon minimum variance method and the music algorithm are analyzed and *** with the former two traditional algorithms,the simulation results show that the music algorithm has good precision and high computational efficiency.

关键词： Direction of Arrival Estimation Uniform Circular Array Antennas Capon Minimum Variance Method Bartlett Beamforming Method music algorithm

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Joint Estimation of Signal and Mutual Coupling Parameters Based on Spatially Spread Polarization Sensitive Array 9

Joint Estimation of Signal and Mutual Coupling Parameters Ba...

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9th Annual Summit and Conference of the Asia-Pacific-Signal-and-Information-Processing-Association (APSIPA ASC)

作者： Li, Huiyong Luo, Zihui Xie, Julan Li, Jun Univ Elect Sci & Technol China Chengdu Sichuan Peoples R China

ISBN: (纸本)9781538615423

A reduced-dimensional music (RD-music) algorithm is proposed to reduce the computation of blind joint direction-of-arrival (DOA), polarization and the mutual coupling parameters estimation algorithm based on spatially spread polarization sensitive uniform linear array (ULA). This algorithm works in two steps. In the first step, DOA parameter and polarization parameters are separated from the mutual coupling through matrix transformation, which are then estimated by RD-music algorithm. In the second step, the mutual coupling coefficients are estimated via eigen-decomposition with modulus constraint. Simulation results show the effectiveness of the proposed method for joint signal parameters and mutual coupling coefficients estimation.

关键词： polarization sensitive array mutual coupling joint parameter estimation music algorithm

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A Modified music algorithm for DOA Estimation

A Modified MUSIC Algorithm for DOA Estimation

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2012 International Conference on Materials and Manufacturing Research (ICMMR 2012)

作者： Su Shujing Zheng Wenqiang The State Key Laboratory of Instrumentation Science and Dynamic Measurement North University of China

In this paper, a method of being modified 2-D DOA estimation is presented. By reconstructing covariance matrix of the received array data, the correlativity of the incident signals is recreased, and mis-division between signal subspace and noise subspace is controlled, therefore the number of estimated signals would be equal to the number of actual incident signals. This method has good performance not only for DOA estimation of the correlation signals, but for DOA estimation of the non-correlation signals. In addition the computational complexity will not increase obviously. The simulation tests verify the validity of the presented algorithm.

关键词： Direction of arrival estimation(DOA) music algorithm reconstructed covariance matrix

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Novel Weak Signal Detection Method Based on Noise Modulation Theory for music algorithm

Novel Weak Signal Detection Method Based on Noise Modulation...

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2012 International Conference on Intelligent System Design and Engineering Applications(2012年智能系统设计与工程应用国际会议 ISDEA 2012)

作者： Jiang Yi Ju Hui Dept of Automation CUlT of ChengDu610225

This paper analyses the noise modulation and noise restrain characteristic of music algorithm on the condition of signal number under-estimation，and proposes a novel weak signal detection method：first modulate... 详细信息

ISBN: (纸本)9781457721205

关键词： Noise Modulation music algorithm Signal dptpetion

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An Airborne/Missile-borne Array Radar Forward-looking Imaging algorithm Based on Super-resolution Method 10

An Airborne/Missile-borne Array Radar Forward-looking Imagin...

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10th International Congress on Image and Signal Processing, BioMedical Engineering and Informatics (CISP-BMEI)

作者： Zhang, Jie Wu, Di Zhu, Daiyin Jiang, Penghui Nanjing Univ Aeronaut & Astronaut Key Lab Radar Imaging & Microwave Photon Minist Educ Coll Elect & Commun Engn Nanjing 211106 Jiangsu Peoples R China

ISBN: (纸本)9781538619377

To overcome the deterioration of azimuth resolution in forward-looking imaging for airborne or missile-borne radar, this paper proposes an array radar forward-looking imaging algorithm based on super-resolution technique. In the novel proposed algorithm, the modified Multiple Signal Classification (music) algorithm is applied to estimate the azimuth positions of the observed targets, followed by the signal accumulation to generate the final image. As is verified by simulation and experimental results, this algorithm can effectively improve the azimuth resolution of radar image in forward-looking direction.

关键词： super-resolution algorithm forward-looking imaging linear array radar music algorithm

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Distributed Source DOA Estimation for More Sources than Sensors Using Sparse Circular Arrays

Distributed Source DOA Estimation for More Sources than Sens...

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International Symposium on Antennas and Propagation (ISAP)

作者： Basikolo, Thomas Ichige, Koichi Arai, Hiroyuki Yokohama Natl Univ Dept Elect & Comp Engn Hodogaya Ku 79-5 Tokiwadai Yokohama Kanagawa 2408501 Japan

ISBN: (纸本)9781538604656

In wireless communications, the signal that a base station receive cannot be regarded as a point source because of the multipath propagation. A distributed source model is more suitable for the realistic scenario due to some environmental phenomenon. This paper presents subspace based method for distributed source direction of arrival estimation. Using nested sparse circular arrays, we are capable of estimating more distributed sources than the number of sensors. Simulation results confirms the effectiveness of the proposed method.

关键词： distributed source music algorithm sparse circular arrays underdetermined DOA estimation

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music for single-snapshot spectral estimation: Stability and super-resolution

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APPLIED AND COMPUTATIONAL HARMONIC ANALYSIS 2016年第1期40卷 33-67页

作者： Liao, Wenjing Fannjiang, Albert Stat & Appl Math Sci Inst Durham NC USA Duke Univ Dept Math Durham NC 27706 USA Univ Calif Davis Dept Math Davis CA 95616 USA

This paper studies the problem of line spectral estimation in the continuum of a bounded interval with one snapshot of array measurement. The single-snapshot measurement data are turned into a Hankel data matrix which admits the Vandermonde decomposition and is suitable for the music algorithm. The music algorithm amounts to finding the null space (the noise space) of the adjoint of the Hankel matrix, forming the noise-space correlation function and identifying the s smallest local minima of the noise-space correlation as the frequency set. In the noise-free case exact reconstruction is guaranteed for any arbitrary set of frequencies as long as the number of measurement data is at least twice the number of distinct frequencies to be recovered. In the presence of noise the stability analysis shows that the perturbation of the noise-space correlation is proportional to the spectral norm of the noise matrix as long as the latter is smaller than the smallest (nonzero) singular value of the noiseless Hankel data matrix. Under the assumption that the true frequencies are separated by at least twice the Rayleigh Length (RL), the stability of the noise-space correlation is proved by means of novel discrete Ingham inequalities which provide bounds on the largest and smallest nonzero singular values of the noiseless Hankel data matrix. The numerical performance of music is tested in comparison with other algorithms such as BLO-OMP and SDP (TV-min). While BLO-OMP is the stablest algorithm for frequencies separated above 4 RL, music becomes the best performing one for frequencies separated between 2 RL and 3 RL. Also, music is more efficient than other methods. music truly shines when the frequency separation drops to 1 RL or below when all other methods fail. Indeed, the resolution length of music decreases to zero as noise decreases to zero as a power law with an exponent smaller than an upper bound established by Donoho. (C) 2014 Elsevier Inc. All rights reserved.

关键词： music algorithm Single-snapshot spectral estimation Stability Super-resolution Discrete Ingham inequalities

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Impact energy level assessment of composite structures using music-ANN approach

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STRUCTURAL CONTROL & HEALTH MONITORING 2016年第5期23卷 825-837页

作者： Zhong, Yongteng Xiang, Jiawei Gao, Haifeng Zhou, Yuqing Wenzhou Univ Coll Mech & Elect Engn Wenzhou 325035 Peoples R China

Impact damage effects on the residual mechanical properties of the structure can be quite detrimental, and failure patterns depend strongly on the impact energy levels. This paper presents impact energy level assessment method using 2D multiple signal classification (music) and artificial neural network (ANN) approach for composite structures. Because uniform linear array has the shortcoming of the half-plane mirror effect, 2D music algorithm using a plum blossom sensor array is firstly applied to locate the position of impact and extract impact energy feature. Secondly, the relation impact energy feature, impact position, and impact energy level at different measurement points are established using ANN approach. Through the trained ANN, the impact energy level can be predicted when the position and impact energy feature results of unknown impact are given as input. Finally, the proposed method is applied to a quasi-isotropic epoxy laminate plate and a large stiffened carbon fiber composite structure showing its successful performance on composite structure. Copyright (C) 2015 John Wiley & Sons, Ltd.

关键词： Impact energy level music algorithm ANN Plum blossom sensor array Composite structure

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DOA Convergence of Unstructured Distributed Arrays with Time-varying and Space-varying Morphologies

DOA Convergence of Unstructured Distributed Arrays with Time...

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作者： Chen, Zhong Texas A&M University

This thesis mainly focuses on the research of the factors that influence the accuracy and efficiency of a UAV-based radio frequency (RF) and microwave data collection system. Swarming UAVs can be utilized to create the unstructured morphing antenna arrays that reduce aliasing and improve convergence in sub-space direction of arrival techniques. This thesis first reports on the ramifications of using unstructured antenna arrays based on sub-space techniques. This work evaluates the classical music algorithm and root-music algorithm, and Fourier domain root-music algorithm (FD Root-music). Compared to the music algorithm, the root-music algorithm avoids the search of spatial spectrum, reduces the computational complexity and improves the ability of real world applications. Then, this thesis comes up with the data model for the UAV swarming system. Based on the data model, this work examines the impact of UAV swarm density and heterogeneity on synthetic aperture DOA convergence. The synthetic aperture is derived from the displacement of distributed UAVs operating in a sparse volumetric swarm. Heterogeneity arises from the changing orientation of a UAV’s antenna and receiving pattern function as it swarms in the distributed cluster of UAVs. This alters the UAVs’ antenna pattern functions over time and alters the convergence and overall performance properties of vector-space direction of arrival techniques. This work evaluates the impact of the swarm density and orientation in this framework and studies the convergence and error using music algorithm. This work also discusses the impact of different type of errors introduced from UAV swarming. Furthermore, this thesis examines the DOA convergence performance of location-varying volumetric random array using music algorithm. Simulation and measurements for up to sixteen elements on a thirty-two-location test platform are provided and comparisons are made to benchmark their performance with theoretical expectations.

关键词： Direction-of-arrival estimation Unmanned aerial vehicles Quaternions Swarming Aperiodic arrays music algorithm Thesis

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