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Separable Synchronous Multi-Innovation Gradient-Based iterative Signal Modeling From On-Line Measurements

IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2022年 71卷

作者： Xu, Ling Ding, Feng Zhu, Quanmin Jiangnan Univ Sch Internet Things Engn Minist Educ Key Lab Adv Proc Control Light Ind Wuxi 214122 Jiangsu Peoples R China Wuxi Vocat Inst Commerce Sch Internet Things Technol Wuxi 214153 Jiangsu Peoples R China Univ West England Dept Engn Design & Math Bristol BS16 1QY Avon England

This article is aimed to study the modeling problems of combinational signals or periodic signals. To overcome the computation complexity of modeling the signals with plenty of characteristic parameters, a parameter separation scheme is developed based on the different characteristic of the signals to be modeled. For the purpose of achieving high-accuracy performance and reducing complexity, two multi-innovation gradient-based iterative (MIGI) subalgorithms are presented by means of gradient search. In terms of the phenomenon that the coupling parameters lead to the inability of algorithms, a separable synchronous (SS) interactive estimation method is proposed to eliminate the coupling parameters and perform the signal modeling algorithm in accordance with the hierarchical principle. By means of simulation experiments, the proposed SS iterative signal modeling algorithm based on the moving batch data is used for estimating a power signal with three sine waves and a periodic square wave signal. The results demonstrate the effectiveness of the proposed method for modeling the combinational signals with multiple frequencies and other periodic signals. Since the proposed method combines real-time data sampling and iterative estimation, it can be used for on-line identification.

关键词： Computational modeling Estimation Data models Technological innovation Frequency estimation Real-time systems iterative algorithms Gradient search hierarchical identification iterative algorithm multi-innovation identification parameter estimation signal modeling

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Analysis on the stiffness iteration of segmental joints in segmental linings: Method and sensitivity analysis

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TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY 2021年 115卷 104043-104043页

作者： Feng, Kun Zhang, Li Guo, Wenqi Yang, Renjie He, Chuan Zhang, Jingxuan Southwest Jiaotong Univ Key Lab Transportat Tunnel Engn Minist Educ Chengdu 610031 Peoples R China Southwest Jiaotong Univ China Japan RSC Struct Res Ctr Chengdu 610031 Peoples R China

In current structural analyses on segmental linings, the bending stiffness of segmental joints is usually treated as a constant, which results in a deviation in the calculated internal forces and deformation. In view of this, a finite element model of segmental linings is established using one ring and two half rings. An iterative algorithm is designed with a 3D curved surface of bending stiffness for the segmental joint, obtained from a series of full-scale tests under different axial force and bending moment cases. The rational convergence criteria for the iterative algorithm are recommended by evaluating the convergence efficiency of the iterative algorithm. Moreover, the influence of load magnitude and initial value of bending stiffness, as well as the changing laws of structural internal forces and deformation with the assembly angles, are presented and analyzed. The results show that with the same load, the convergence of the iterative algorithm in staggered-jointed assembly structures (STGS) is better than that of straight-jointed assembly structures (STRS), owing to its greater overall stiffness. The initial input value of bending stiffness has no effect on the convergence of the proposed iterative algorithm, and generally the convergence performance in STGS is better than that in STRS. In STRS, the bending moment is most sensitive to the changes of assembly angles, while in STGS the assembly angles have great influence on both the bending moment and structural displacement. Without the stiffness iteration, the maximum differences for maximum axial force, bending moment, and displacement under different assembly angle in STRS are 11.7%, 31.9% and 22.3%, respectively, and that differences in STGS are 10.4%, 59.3% and 35.1%, respectively. With the stiffness iterative method, the increase amplitude of the maximum axial force, the maximum bending moment, and the maximum displacement in STRS and STGS are 50.0%, 317.4%, 77.1% and 41.9%, 459.3%, 156.5%, respectivel

关键词： Shield tunnel Segmental joint Bending stiffness iterative algorithm Convergence performance

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Fictitious time integration method for seeking periodic orbits of nonlinear dynamical systems

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INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS 2023年 152卷

作者： Liu, Chein-Shan Atluri, Satya N. Dai, Honghua Natl Taiwan Ocean Univ Ctr Excellence Ocean Engn Keelung 202301 Taiwan Texas Tech Univ Ctr Adv Res Engn Sci Lubbock TX USA Northwestern Polytech Univ Coll Astronaut Xian 710072 Peoples R China

In the paper, we compute the period and periodic orbit of an n-dimensional nonlinear dynamical system by developing two iterative algorithms based on the fictitious time integration method (FTIM). Periodicity condition, also known as the Poincare map, is a necessary condition for the existence of a periodic motion in the state space, which consists of n implicit nonlinear algebraic equations (NAEs). Instead of solving the NAEs by the Newton-Raphson method, we derive an equivalent nonlinear scalar equation to determine unknown period by using the FTIM. The resulting sequence of the iterated periods monotonically converges to a desired period, wherein the unknown initial point on the periodic orbit is determined simultaneously. We find that the second iterative algorithm using the matrix shape function to convert the periodic problem into a corresponding initial value problem is convergent faster than the first iterative algorithm. A key point is that the periodicity condition is satisfied automatically by the second iterative algorithm when the terminal values of the new variables are convergent. Numerical examples exhibit some major advantages of these two iterative algorithms.

关键词： Nonlinear dynamical system Periodic orbit Matrix shape function Fictitious time integration method iterative algorithm

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Static output feedback negative imaginary controller synthesis with an H_∞ norm bound

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AUTOMATICA 2021年 126卷 109157-109157页

作者： Ren, Dingchao Xiong, Junlin Ho, Daniel W. C. Univ Sci & Technol China Dept Automat Hefei 230026 Peoples R China City Univ Hong Kong Dept Math Kowloon Hong Kong Peoples R China

A large number of practical systems can be modeled as negative imaginary (NI) systems. In this paper, we investigate the problem of static output feedback (SOF) NI controller design with H-infinity performance. Motivated by the two-stage framework for SOF stabilization, a sufficient condition is derived for the SOF controller synthesis. An iterative LMI-based algorithm is suggested to find an SOF controller. The algorithm consists of two stages: (1) finding an initial output injection controller;(2) computing a desired SOF controller. In addition, a numerical example is provided to verify the proposed method. (C) 2020 Published by Elsevier Ltd.

关键词： H-infinity control iterative algorithm Linear matrix inequality Negative imaginary system Static output feedback

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Adaptive Sampling by Information Maximization

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Physical Review Letters 2002年第22期88卷 228104-228104页

作者： Christian K. Machens Innovationskolleg Theoretische Biologie Invalidenstrasse 43 Humboldt-University Berlin 10115 Berlin Germany

The investigation of input-output systems often requires a sophisticated choice of test inputs to make the best use of limited experimental time. Here we present an iterative algorithm that continuously adjusts an ensemble of test inputs on-line, subject to the data already acquired about the system under study. The algorithm focuses the input ensemble by maximizing the mutual information between input and output. We apply the algorithm to simulated neurophysiological experiments and show that it serves to extract the ensemble of stimuli that a given neural system “expects” as a result of its natural history.

关键词： .assume outputs Input-Output input and output iterative algorithm test inputs input distribution

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Combination of voxel-based and projection-based methods in terms of convergence for CT reconstruction

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MEDICAL PHYSICS 2016年第6期43卷 2828-2834页

作者： Chukanov, Viacheslav Bergner, Frank SPbPU St Petersburg 195251 Russia Philips GmbH Res Labs D-22335 Hamburg Germany

Purpose: Recent applications of iterative image reconstruction algorithms to multislice helical CT have shown that iterative reconstruction can significantly improve image quality and reduce artifacts. In this paper, the authors introduce a combination of two different algorithms with different convergence properties: ordered subsets separable paraboloidal surrogates (OS-SPS) and iterative coordinate descent (ICD). The first one updates image voxels simultaneously, slightly changing attenuation values iteration by iteration. The second algorithm updates image voxel by voxel, each time performing full forward and backward projections of the voxel. It has been shown that ICD converges better at high-frequency areas and requires more iterations to reconstruct low-frequency components of the image. In contrast to ICD, SPS requires multiple iterations to reconstruct high-frequency areas. In this paper, the authors introduce an algorithm which leverages the benefits of both ICD and SPS. Methods: The idea is to update the entire image with SPS, determine high-frequency components, and focus ICD computations on it using nonhomogeneous ICD update. Results: The authors have successfully implemented OS-SPS, ICD, their hybrid approach, and few variations of ICD based on spatially nonuniform updates. Conclusions: The authors have examined the convergence of different algorithms and found that proposed algorithm converges better than OS-SPS, ICD, as well as various improved variants of ICD. (C) 2016 American Association of Physicists in Medicine.

关键词： computed tomography iterative algorithm coordinate descent separable paraboloidal surrogate ordered subsets

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KACZMARZ algorithm AND FRAMES

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INTERNATIONAL JOURNAL OF WAVELETS MULTIRESOLUTION AND INFORMATION PROCESSING 2013年第5期11卷 1350036-1350036页

作者： Czaja, Wojciech Tanis, James H. Univ Maryland Dept Math College Pk MD 20742 USA Rice Univ Dept Math Houston TX 77251 USA

Sequences of unit vectors for which the Kaczmarz algorithm always converges in Hilbert space can be characterized in frame theory by tight frames with constant 1. We generalize this result to the context of frames and bases. In particular, we show that the only effective sequences which are Riesz bases are orthonormal bases. Moreover, we consider the infinite system of linear algebraic equations Ax = b and characterize the (bounded) matrices A for which the Kaczmarz algorithm always converges to a solution.

关键词： Kaczmarz algorithm frame theory iterative algorithm

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Minimum-norm reconstruction for sensitivity-encoded magnetic resonance spectroscopic imaging

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MAGNETIC RESONANCE IN MEDICINE 2006年第2期55卷 287-295页

作者： Sánchez-González, J Tsao, J Dydak, U Desco, M Boesiger, P Pruessmann, KP Hosp Gen Gregorio Maranon Lab Imagen Med Expt E-28007 Madrid Spain Swiss Fed Inst Technol Inst Biomed Engn Zurich Switzerland Univ Zurich Zurich Switzerland

In this work we propose minimum-norm reconstruction as a means to enhance the spatial response behavior in parallel spectroscopic MRI. By directly optimizing the shape of the spatial response function (SRF), the new method accounts for coil sensitivity variation across individual voxels and their side lobes. In this fashion, it mitigates the signal contamination and side-lobe aliasing, to which previous techniques are susceptible at low resolution. Although the computational burden is higher, minimum-norm reconstruction is shown to be feasible using an iterative algorithm. Benefits in terms of SRF shape and artifact suppression are demonstrated.

关键词： sensitivity encoding (SENSE) MR spectroscopic imaging (MRSI) minimum-norm reconstruction strong reconstruction iterative algorithm

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A Fast algorithm for Matching Remote Scene Images

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Geo-Spatial Information Science 2008年第3期11卷 197-200页

作者： LIU Jin YAN Li School of Geodesy and Geomatics Wuhan University 129 Luoyu Road Wuhan 430079 China State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University 129 Luoyu Road Wuhan 430079 China.

An iterative algorithm to calculate mutual correlation using hierarchical key points and the search space mark principle is proposed. An effective algorithm is designed to improve the matching speed. By hi-erarchical key point algorithm and mutual correlation coefficients of the matching images, the important points can be iteratively calculated in the images hierarchically, and the correlation coefficient can be ob-tained with satisfactory precision. Massive spots in the parameter space which are impossible to match can be removed by the search space mark principle. Two approximate continuities in the correlation image matching process, the image gray level distribution continuity and the correlation coefficient value in the parameter space continuity, are considered in the method. The experiments show that the new algorithm can greatly enhance matching speed and achieve accurate matching results.

关键词： image correlation matching fast algorithm iterative algorithm

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Alternative threshold-based channel estimation and message-passing-based symbol detection in MIMO-OTFS systems using superimposed pilots

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PHYSICAL COMMUNICATION 2023年第1期59卷

作者： Ouchikh, Rabah Aissa-El-Bey, Abdeldjalil Chonavel, Thierry Djeddou, Mustapha Ecole Mil Polytech Lab Telecommun Bordj El Bahri Algeria CNRS UMR 6285 IMT Atlantique Lab STICC F-29238 Brest France

In this work, we investigate the challenging problem of channel estimation in high-mobility environ-ments for advanced mobile communication systems (5G and beyond). First, we propose an iterative algorithm for channel estimation and symbol detection in the delay-Doppler domain for multiple-input multiple-output orthogonal time-frequency space (OTFS) system. The proposed algorithm is based on a superimposed pilot pattern to improve the spectral efficiency of the system. It iterates between data-aided channel estimation and message-passing-aided data detection. The channel estimation step is based on a threshold method. This step considers interference-plus-noise caused by the data symbols and the additive noise to adapt the threshold at each iteration. The data detection step is based on an adapted version of the message-passing algorithm proposed in the literature for uncoded OTFS. Then, to improve the channel estimation efficiency, we suggest an interference cancellation scheme executed at each iteration of the proposed algorithm. Finally, we compare the computational complexity and the achieved performance in terms of normalized mean square error of channel estimation, bit error rate, and spectral efficiency against five state-of the-art methods.(c) 2023 Elsevier B.V. All rights reserved.

关键词： MIMO OTFS Channel estimation iterative algorithm Superimposed pilot

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