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Research on monopulse forward-looking high-resolution imaging algorithm based on adaptive iteration

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Defence Technology（防务技术） 2020年第1期16卷 158-171页

作者： Cheng Cheng Xiao-dong Zhou Min Gao Zhu-lin Zong Yong-xiang Ji Bo Yu Department of Missile Engineering Army Engineering UniversityNo.97 Westroad HepingShijiazhuangChina Department of Ammunition Engineering Army Engineering UniversityNo.97 Westroad HepingShijiazhuangChina Research Institute of Electronic Science and Technology University of Electronic Science and TechnologyNo.4Section 2Jianbei RoadChengduChina China Huayin Weapon Test Center No.450 Yuemiao StreetHuayinShaanxiChina North Automatic Control Technology Institute No.351 Tiyu RoadTaiyuanChina

In this paper,we proposed a monopulse forward-looking high-resolution imaging algorithm based on adaptive iteration for missile-borne detector.Through iteration,the proposed algorithm automatically selects the echo signal of isolated strong-scattering points from the receiving echo signal data to accurately estimate the actual optimal monopulse response curve(MRC) of the same distance range,and we applied optimal MRC to realize the azimuth self-focusing in the process of imaging.We use real-time echo data to perform error correction for obtaining the optimal MRC,and the azimuth angulation accuracy may reach the optimum at a certain distance dimension.We experimentally demonstrate the validity,reliability and high performance of the proposed algorithm.The azimuth angulation accuracy may reach up to ten times of the detection beam-width.The simulation experiments have verified the feasibility of this strategy,with the average height measurement error being 7.8%.In the out-field unmanned aerial vehicle(UAV) tests,the height measurement error is less than 25 m,and the whole response time can satisfy the requirements of a missile-borne detector.

关键词： Monopulse imaging High-resolution Adaptive iteration Missile-borne detector

A Unification of the Concepts of the Variational iteration, Adomian Decomposition and Picard iteration Methods;and a Local Variational iteration Method

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Computer Modeling in Engineering & Sciences 2016年第6期111卷 567-585页

作者： Xuechuan Wang Satya N.Atluri Texas Tech University Center for Advanced Research in the Engineering Sciences Northwestern Polytechnical University China

This paper compares the variational iteration method(VIM),the Adomian decomposition method(ADM)and the Picard iteration method(PIM)for solving a system of first o rder n onlinear o rdinary d ifferential e quations(ODEs).A unification of the concepts underlying these three methods is attempted by considering a very general iterative algorithm for VIM.It is found that all the three methods can be regarded as special cases of using a very general matrix of Lagrange multipliers in the iterative algorithm of VIM.The global variational iteration method is briefly reviewed,and further recast into a Local VIM,which is much more convenient and capable of predicting long term complex dynamic responses of nonlinear systems even if they are chaotic.

关键词： Variational iteration method Adomian decomposition method Picard iteration method asymptotic technique nonlinear dynamical system

Efficient Orbit Propagation of Orbital Elements Using Modified Chebyshev Picard iteration Method

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Computer Modeling in Engineering & Sciences 2016年第1期111卷 65-81页

作者： J.L.Read A.Bani Younes J.L.Junkins Graduate Research Assistant Texas A&M UniversityCollege StationTXUSA. Assistant Professor Khalifa UniversityAbu DhabiUAE. Distinguished Professor Texas A&M UniversityCollege StationTXUSA.

This paper focuses on propagating perturbed two-body motion using orbital elements combined with a novel integration technique.While previous studies show that Modified Chebyshev Picard iteration(MCPI)is a powerful tool used to propagate position and velocity,the present results show that using orbital elements to propagate the state vector reduces the number of MCPI iterations and nodes required,which is especially useful for reducing the computation time when including computationally-intensive calculations such as Spherical Harmonic gravity,and it also converges for>5.5x as many revolutions using a single segment when compared with cartesian propagation.Results for the Classical Orbital Elements and the Modified Equinoctial Orbital Elements(the latter provides singularity-free solutions)show that state propagation using these variables is inherently well-suited to the propagation method chosen.Additional benefits are achieved using a segmentation scheme,while future expansion to the two-point boundary value problem is expected to increase the domain of convergence compared with the cartesian case.MCPI is an iterative numerical method used to solve linear and nonlinear,ordinary differential equations(ODEs).It is a fusion of orthogonal Chebyshev function approximation with Picard iteration that approximates a long-arc trajectory at every iteration.Previous studies have shown that it outperforms the state of the practice numerical integrators of ODEs in a serial computing environment;since MCPI is inherently massively parallelizable,this capability is expected to increase the computational efficiency of the method presented.

关键词： Propagation Integration Orbital Mechanics Classical Elements Modified Equinoctial Chebyshev Picard iteration MCPI Polynomials Initial Value Problem IVP.

Low-Complexity Signal Detection Based on Relaxation iteration Method in Massive MIMO Systems

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China Communications 2015年第S1期12卷 1-8页

作者： GUO Ruohan LI Xiaohui FU Weihong HEI Yongqiang State Key Laboratory of Integrated Service Networks Xidian University

Minimum mean square error(MMSE) detection algorithm can achieve nearly optimal performance when the number of antennas at the base station(BS) is large enough compared to the number of users. But the traditional MMSE involves complicated matrix inversion. In this paper, we propose a modified MMSE algorithm which exploits the channel characteristics occurring in massive multiple-input multipleoutput(MIMO) channels and the relaxation iteration(RI) method to avoid the matrix inversion. A proper initial solution is given to accelerate the convergence speed. In addition, we point out that the channel estimation scheme used in channel hardening-exploiting message passing(CHEMP) receiver is very appropriate for our proposed detection algorithm. Simulation results verify that the proposed algorithm can achieve very close performance of the traditional MMSE algorithm with a small number of iterations.

关键词： massive MIMO detection minimum mean square error relaxation iteration channel estimation

On Minimization of Upper Bound for the Convergence Rate of the QHSS iteration Method

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Communications on Applied Mathematics and Computation 2019年第2期1卷 263-282页

作者： Wen-Ting Wu State Key Laboratory of Scientific/Engineering Computing Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of Sciences. P.O. Box 2719. Beijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

For an upper bound of the spectral radius of the QHSS (quasi Hermitian and skew-Hermitian splitting) iteration matrix which can also bound the contraction factor of the QHSS iteration method,we give its minimum point under the conditions which guarantee that the upper bound is strictly less than one. This provides a good choice of the involved iteration parameters,so that the convergence rate of the QHSS iteration method can be significantly improved.

关键词： System of linear equations Non-Hermitian matrix QHSS iteration method Convergence rate

Some geometrical iteration methods for nonlinear equations

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Applied Mathematics(A Journal of Chinese Universities) 2008年第1期23卷 25-30页

作者： LU Xing-jiang QIAN Chun Dept. of Math Zhejiang Univ. Hangzhou 310027 China. College of Statist. and Comput. Sci. Zhejiang Gongshang Univ. Hangzhou 310018China.

This paper describes geometrical essentials of some iteration methods （e.g. Newton iteration, secant line method, etc.） for solving nonlinear equations and advances some geometrical methods of iteration that are fle... 详细信息

关键词： nonlinear equation iteration geometric method.

Adaptive window iteration algorithm for enhancing 3D shape recovery from image focus

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Chinese Optics Letters 2019年第6期17卷 24-30页

作者：李龙潘志燕崔浩阳刘娇容杨守臣刘丽兰田应仲王文斌 School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200072China Shanghai Key Laboratory of Intelligent Manufacturing and Robotics Shanghai UniversityShanghai 200072China Mechanical and Electrical Engineering School Shenzhen PolytechnicShenzhen 518055China

Depth from focus(DFF)is a technique for estimating the depth and three-dimensional(3D)shape of an object from a multi-focus image sequence.At present,focus evaluation algorithms based on DFF technology will always cause inaccuracies in deep map recovery from image focus.There are two main reasons behind this issue.The first is that the window size of the focus evaluation operator has been fixed.Therefore,for some pixels,enough neighbor information cannot be covered in a fixed window and is easily disturbed by noise,which results in distortion of the model.For other pixels,the fixed window is too large,which increases the computational burden.The second is the level of difficulty to get the full focus pixels,even though the focus evaluation calculation in the actual calculation process has been completed.In order to overcome these problems,an adaptive window iteration algorithm is proposed to enhance image focus for accurate depth estimation.This algorithm will automatically adjust the window size based on gray differences in a window that aims to solve the fixed window problem.Besides that,it will also iterate evaluation values to enhance the focus evaluation of each pixel.Comparative analysis of the evaluation indicators and model quality has shown the effectiveness of the proposed adaptive window iteration algorithm.

关键词： Depth from focus(DFF) three-dimensional iteration algorithm

A distributed inverse iteration method for eigenvalue analysis of interconnected power systems

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Science China(Technological Sciences) 2007年第6期50卷 774-785页

作者： SHEN Chen CHEN Ying ZHANG Xu State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China

Since China power grids have a hierarchical architecture in operation and man- agement, centralized computation patterns are difficult to meet the demands of small-signal-stability analysis of the bulk interconnected power systems. A dis- tributed eigenvalue algorithm derived from the inverse iteration method is pro- posed. It can not only obtain eigenvalues and eigenvectors from power system state matrix but also provide participation factors of all generators. In the comput- ing process, the algorithm only requires exchanging data of boundary nodes and a small amount of other information of different regions. Therefore, it is very suitable to be deployed in a WAN (wide area network) based distributed environment. The algorithm has been tested on an IEEE39 system.

关键词： distributed computing, eigenvalue, small signal stability, inverse iteration method

A Fast iteration Method for Mixture Regression Problem

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Journal of Applied Mathematics and Physics 2015年第9期3卷 1100-1107页

作者： Dawei Lang Wanzhou Ye College of Sciences Shanghai University Shanghai China

In this paper, we propose a Fast iteration Method for solving mixture regression problem, which can be treated as a model-based clustering. Compared to the EM algorithm, the proposed method is faster, more flexible and can solve mixture regression problem with different error distributions (i.e. Laplace and t distribution). Extensive numeric experiments show that our proposed method has better performance on randomly simulations and real data.

关键词： Mixture Regression Problem Fast iteration Method Model-Based Clustering