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Fast iterative reconstruction for photoacoustic tomography using learned physical model: Theoretical validation

PHOTOACOUSTICS 2023年 29卷 100452页

作者： Hsu, Ko-Tsung Guan, Steven Chitnis, Parag, V George Mason Univ Dept Bioengn Fairfax VA 22030 USA

iterative reconstruction has demonstrated superior performance in medical imaging under compressed, sparse, and limited-view sensing scenarios. However, iterative reconstruction algorithms are slow to converge and rely heavily on hand-crafted parameters to achieve good performance. Many iterations are usually required to reconstruct a high-quality image, which is computationally expensive due to repeated evaluations of the physical model. While learned iterative reconstruction approaches such as model-based learning (MBLr) can reduce the number of iterations through convolutional neural networks, it still requires repeated evaluations of the physical models at each iteration. Therefore, the goal of this study is to develop a Fast iterative Reconstruction (FIRe) algorithm that incorporates a learned physical model into the learned iterative reconstruction scheme to further reduce the reconstruction time while maintaining robust reconstruction performance. We also propose an effi-cient training scheme for FIRe, which releases the enormous memory footprint required by learned iterative reconstruction methods through the concept of recursive training. The results of our proposed method demon-strate comparable reconstruction performance to learned iterative reconstruction methods with a 9x reduction in computation time and a 620x reduction in computation time compared to variational reconstruction.

关键词： Photoacoustic tomography iterative algorithm Deep learning Image reconstruction Learned forward operator Neural operator

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Existence of Solution for Infinite System of Nonlinear Singular Integral Equations and Semi-Analytic Method to Solve it

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IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY TRANSACTION A-SCIENCE 2021年第1期45卷 235-245页

作者： Hazarika, Bipan Rabbani, Mohsen Agarwal, Ravi P. Das, Anupam Arab, Reza Gauhati Univ Dept Math Gauhati 781014 Assam India Islamic Azad Univ Dept Math Sari Branch Sari Iran Texas A&M Univ Dept Math Kingsville TX 78363 USA Rajiv Gandhi Univ Dept Math Rono Hills Doimukh 791112 Arunachal Prade India Cotton Univ Dept Math Gauhati 781001 Assam India

In this article, solvability of infinite system of nonlinear singular integral equations of two variables in Banach sequence spaces c(0) and l(1) is investigated. For this purpose, Hausdorff measure of noncompactness (in short, Hausdorff MNC) and Meir-Keeler condensing operators are employed. The guarantee of our results are given by some examples. Also to approach an approximation of semi-analytic solution, we introduce a coupled modified homotopy perturbation and Adomian decomposition method. Thus, an iterative algorithm is constructed to find the above solution. The numerical results show that the produced sequence to approximate the solution has a high accuracy.

关键词： Hausdorff measure of noncompactness (Hausdorff MNC) Infinite system of singular integral equation Meir-Keeler condensing operators Modified homotopy iterative algorithm

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Least squares solution of the quaternion Sylvester tensor equation

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LINEAR & MULTILINEAR ALGEBRA 2021年第1期69卷 104-130页

作者： Wang, Qing-Wen Xu, Xiangjian Duan, Xuefeng Shanghai Univ Dept Math Shanghai 200114 Peoples R China Nantong Univ Sch Sci Nantong Jiangsu Peoples R China Guilin Univ Elect Technol Sch Math & Computat Sci Guilin Peoples R China

This paper is concerned with the solution to the least squares problem for the quaternion Sylvester tensor equation. An iterative algorithm based on tensor format is presented to solve this problem. The convergence properties of the proposed iterative method are studied. We also consider the best approximate problem related to quaternion Sylvester tensor equation. Numerical examples are provided to confirm the theoretical results, which demonstrate that the proposed algorithm is effective and feasible for solving the least squares problem of the quaternion Sylvester tensor equation.

关键词： Quaternion tensor Sylvester tensor equation iterative algorithm least squares solution

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Reconsidering Herbert A. Simon's Major Themes in Economics: Towards an Experimentally Grounded Capital Structure Theory Drawing from His Methodological Conjectures (Apr, 10.1007/s10614-018-9808-7, 2020)

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COMPUTATIONAL ECONOMICS 2021年第3期57卷 825-826页

作者： Bucciarelli, Edgardo Mattoscio, Nicola Univ G dAnnunzio Dept Philosoph Pedag & Econ Quantitat Sci Sect Quantitat Methods & Econ Viale Pindaro 42 I-65127 Pescara Italy

This is an erratum to the article entitled "Reconsidering Herbert A. Simon's Major Themes in Economics: Towards an Experimentally Grounded Capital Structure Theory Drawing from His Methodological Conjectures&... 详细信息

关键词： Experimental economics Design research Abduction iterative algorithm Data-driven discovery Corporate finance JEL ClassificationC81 C91 D81 D91 G32

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Asymptotic pointwise error estimates for reconstructing shift-invariant signals with generators in a hybrid-norm space

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JOURNAL OF INEQUALITIES AND APPLICATIONS 2021年第1期2021卷 1-14页

作者： Li, Haizhen Fan, Xiao Tang, Yan Guilin Univ Elect Technol Inst Informat Technol Guilin Peoples R China Sun Yat Sen Univ Sch Elect & Informat Technol Guangzhou Peoples R China Guilin Univ Elect Technol Sch Math & Computat Sci Guilin Peoples R China

Sampling and reconstruction of signals in a shift-invariant space are generally studied under the requirement that the generator is in a stronger Wiener amalgam space, and the error estimates are usually given in the sense of L-p,L-1/omega-norm. Since we often need to reflect the local characteristics of reconstructing error, the asymptotic pointwise error estimates for nonuniform and average sampling in a non-decaying shift-invariant space are discussed under the assumption that the generator is in a hybrid-norm space. Based on Lemma 2.1-Lemma 2.6, we first rewrite the iterative reconstruction algorithms for two kinds of average sampling functionals and prove their convergence. Then, the asymptotic pointwise error estimates are presented for two algorithms under the case that the average samples are corrupted by noise.

关键词： Hybrid-norm space Nonuniform average sampling Non-decaying signals iterative algorithm Asymptotic pointwise error estimate

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Multiple-sets split feasibility problem and split equality fixed point problem for firmly quasi-nonexpansive or nonexpansive mappings

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JOURNAL OF INEQUALITIES AND APPLICATIONS 2021年第1期2021卷 1-21页

作者： Xu, Tongxin Shi, Luoyi TianGong Univ Sch Math Sci Tianjin 300387 Peoples R China

In this paper, we propose a new iterative algorithm for solving the multiple-sets split feasibility problem (MSSFP for short) and the split equality fixed point problem (SEFPP for short) with firmly quasi-nonexpansive operators or nonexpansive operators in real Hilbert spaces. Under mild conditions, we prove strong convergence theorems for the algorithm by using the projection method and the properties of projection operators. The result improves and extends the corresponding ones announced by some others in the earlier and recent literature.

关键词： Mutiple-sets split feasibility problem Split equality fixed point problem Strong convergence Hilbert spaces iterative algorithm

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Estimation of Ground Subsidence Deformation Induced by Underground Coal Mining with GNSS-IR

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REMOTE SENSING 2023年第1期15卷 96页

作者： Bo, Huaizhi Li, Yunwei Tan, Xianfeng Dong, Zhoubin Zheng, Guodong Wang, Qi Yu, Kegen Lunan Geol & Explorat Inst Shandong Prov China Jining 272000 Peoples R China Minist Nat Resources China Technol Innovat Ctr Restorat & Reclamat Min induce Jining 272000 Peoples R China Shandong Univ Sch Space Sci & Phys Weihai 264200 Peoples R China Chengdu Inst Surveying & Mapping Survey Chengdu 610081 Peoples R China China Univ Min & Technol Sch Environm Sci & Spatial Informat Xuzhou 221116 Peoples R China

In this paper, GNSS interferometric reflectometry (GNSS-IR) is firstly proposed to estimate ground surface subsidence caused by underground coal mining. Ground subsidence on the main direction of a coal seam is described by using the probability integral model (PIM) with unknown parameters. Based on the laws of reflection in geometric optics, model of GNSS signal-to-noise (SNR) observation for the tilt surface, which results from differential subsidence of ground points, is derived. Semi-cycle SNR observations fitting method is used to determine the phase of the SNR series. Phase variation of the SNR series is used to calculate reflector height of ground specular reflection point. Based on the reflector height and ground tilt angle, an iterative algorithm is proposed to determine coefficients of PIM, and thus subsidence of the ground reflection point. By using the low-cost navigational GNSS receiver and antenna, an experimental campaign was conducted to validate the proposed method. The results show that, when the maximum subsidence is 3076 mm, the maximum relative error of the proposed method-based subsidence estimation is 5.5%. This study also suggests that, based on the proposed method, the navigational GNSS instrument can be treated as a new type of sensor for continuously measuring ground subsidence deformation in a cost-effective way.

关键词： ground subsidence probability integral model (PIM) GNSS-IR phase variation of SNR iterative algorithm

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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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A study on ultrasonic process tomography for dispersed small particle system visualisation

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INTERNATIONAL JOURNAL OF COMPUTER APPLICATIONS IN TECHNOLOGY 2021年第2-3期67卷 176-184页

作者： Meng, Zhiheng Gu, Jianfei Chou, Yongxin Changshu Inst Technol Sch Elect & Automat Engn Changshu Jiangsu Peoples R China

The present challenge in the ultrasonic process tomography on dispersed small particle systems is that it is hard to obtain the accurate algorithm for reconstruction. For more accurate reconstruction, this work proposes an improved GMRES (Generalised Minimal Residual) algorithm based on generalised minimal residual iteration and mean filtering method. To verify the feasibility of the algorithm for dispersed small particle system visualisation, a linear acoustic attenuation model is developed to obtain the projection data of ultrasonic array. Then, we compared it with the current mainstream reconstruction algorithms under the conditions of the less effective information by solving the underdetermined equations. It is shown that this method can present a high reconstruction precision in the cases of numerical simulations, and reasonably reflect the cross section of dispersed small particle distribution. In the numerical simulations, the imaging accuracy of improved GMRES algorithm can reach about 90%.

关键词： ultrasonic method dispersed particle particulate two-phase flow back projection 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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