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Cross-sectional photoacoustic tomography image reconstruction with a multi-curve integration model

COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020年 197卷 105731-105731页

作者： Qi, Li Huang, Shixian Li, Xipan Zhang, Shuangyang Lu, Lijun Feng, Qianjin Chen, Wufan Southern Med Univ Guangdong Prov Key Lab Med Image Proc 1023 Shatai Rd Guangzhou 510900 Guangdong Peoples R China Southern Med Univ Sch Biomed Engn 1023 Shatai Rd Guangzhou 510900 Guangdong Peoples R China

Background and objective: In acoustic inversion of photoacoustic tomography (PAT), an imaging model that precisely describes both the ultrasonic wave propagation and the detector properties is of crucial importance. Inspired by the multi-stripe integration model in clinical X-ray computed tomography systems, in this work, we introduce the Multi-Curve-Integration-based acoustic inversion for cross-sectional Photoacoustic Tomography (MCI-PAT). Methods: We assumed that in cross-sectional PAT system, the three-dimensional (3-D) wave propagation problem could be reduced to a two-dimensional (2-D) problem in a limited, yet sufficient field of view. Under such condition, the MCI-PAT imaging model is generated by integrating several circular acoustic curves, the centers of which are points evenly distributed on the finite-size ultrasonic transducer surface. In this way, the spatial detector response is taken into account, while its computational burden does not largely increase because the integration process is performed only on a 2-D plane. Results: As proven by simulation, phantom and in vivo small animal experiments, the MCI-PAT method leads to promising improvement in PAT image quality. Comparing to traditional imaging models that considered only a single acoustic curve, our proposed method successfully improved the visibility of small structures and achieved evident enhancement on signal-to-noise ratio. Conclusions: The performance of the MCI-PAT method demonstrates that for cross-sectional PAT, a 2-D simplification of the propagation of multiple photoacoustic waves is feasible. Due to its simplicity, our method can be used as an add-on to current system models considering only a single acoustic curve. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Photoacoustic tomography Image reconstruction iterative algorithm

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Bumpless H∞ control for periodic piecewise linear systems

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AUTOMATICA 2022年 135卷 109941-109941页

作者： Song, Xiaoqi Lam, James Univ Hong Kong Dept Mech Engn Pokfulam Rd Hong Kong Peoples R China HKU Shenzhen Inst Res & Innovat HKU SIRI Shenzhen 518057 Peoples R China

This paper investigates the bumpless H-infinity control problem based on exponential stability and L-2-gain analyses for a class of periodic piecewise linear systems. A novel characterization of bumpless transfer among a variety of subsystem controllers satisfying some interpolation constraints is introduced. By utilizing adjustable interpolation functions and multiple Lyapunov functions, more flexibility is provided so as to guarantee a desirable closed-loop performance and trajectory smoothness. Since the problem formulated boils down to a feasibility problem involving nonlinear matrix inequalities, an iterative algorithm which solves a series of convex optimization problems is developed. Numerical examples are presented to show the validity of the proposed methods. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Bumpless transfer H-infinity performance Interpolative controllers iterative algorithm Periodic piecewise systems

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Measure of noncompactness of a new space of tempered sequences and its application on fractional differential equations

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CHAOS SOLITONS & FRACTALS 2020年 140卷 110221-110221页

作者： Rabbani, Mohsen Das, Anupam Hazarika, Bipan Arab, Reza Islamic Azad Univ Sari Branch Dept Math Sari Iran Rajiv Gandhi Univ Dept Math Rono Hills Doimukh 791112 Arunachal Prade India Cotton Univ Dept Math Gauhati 781001 Assam India Gauhati Univ Dept Math Gauhati 781014 Assam India

The purpose of this article is to introduce a new tempered sequence space and obtain the measure of noncompactness in this space. Using the measure of noncompactness and generalized Darbo fixed point theorem, we discuss the existence of solutions of an infinite system of fractional differential equations. Also we provide an example to highlight and establish the importance of our main result. Finally, we approach the solution of the example with high accuracy, by a convergent iterative algorithm with the help of modified homotopy perturbation method. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Measure of noncompactness Tempered space Fractional differential equations Darbo fixed point theorem iterative algorithm Modified homotopy perturbation

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Coupling prediction model and influencing factors analysis of injection and production gas flow rate and wellhead pressure for compressed air energy storage in salt cavern

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JOURNAL OF ENERGY STORAGE 2024年 100卷

作者： Ren, Qianyu Wang, Jiangshuai Fu, Pan Changzhou Univ Sch Petr & Nat Gas Engn Changzhou Jiangsu Peoples R China CNPC Engn Technol R&D Co Ltd Beijing Peoples R China Natl Engn Res Ctr Oil & Gas Drilling & Complet Tec Beijing Peoples R China

In order to accurately predict the injection and production gas flow rate and wellhead pressure for compressed air energy storage in salt cavern, a coupled prediction model of injection and production gas flow rate and wellhead pressure based on gas pipe flow theory was established in this paper. And, a high-precision and highspeed iterative solution algorithm was proposed to achieve accurate and rapid prediction of injection and production gas flow rate, wellhead pressure, and total pressure loss. Furthermore, the influences of factors such as cavity connectivity, number of cavities, cavity pressure, depth of injection and production wells, number of injection and production columns, size of injection and production columns, and injection and production medium on injection and production gas flow rate, wellhead pressure, and total pressure loss were discussed. The research results indicate that: (1) There are good stability, fast convergence speed, and good consistency between the predicted results and on-site measured data for the model. (2) Under the condition that cavity is connected, the total injection-production flow will be equally distributed to each injection-production well, and the wellhead pressure and total pressure loss of each injection-production well are the same. When the cavity is not connected, the cavity with larger pressure has greater flow rate and total pressure loss under gas production condition, and the cavity with larger pressure has smaller flow rate and greater total pressure loss under gas injection condition. (3) With the increase in the number of chambers, the decrease in chamber pressure, the increase in injection production well depth, the increase in the number of injection production columns, and the decrease in the size of injection production columns, the single tube injection production gas flow rate decreases. However, the changes in wellhead pressure and total pressure loss are not only influenced by various factors, but al

关键词： Compressed air energy storage in salt cavern Gas injection and production flow distribution Wellhead pressure prediction Coupling model iterative algorithm

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Goos-Hänchen-like shifts in atom optics

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Physical Review A 2008年第6期77卷 063608-063608页

作者： Jianhua Huang Zhenglu Duan Hong Y. Ling Weiping Zhang State Key Laboratory of Precision Spectroscopy Department of Physics East China Normal University Shanghai 200062 People’s Republic of China Department of Physics and Astronomy Rowan University Glassboro New Jersey 08028-1700 USA

We consider the propagation of a matter wave packet of two-level atoms through a square potential created by a super-Gaussian laser beam. We explore the matter wave analog of Goos-Hänchen shift within the framework of atom optics where the roles of atom and light are exchanged with respect to conventional optics. Using a vector theory, where atoms are treated as particles possessing two internal spin components, we show that not only large negative but also large positive Goos-Hänchen shifts can occur in the reflected atomic beam.

关键词： ABSORBING MEDIA LATERAL SHIFT LIGHT-BEAM iterative algorithm TOTAL REFLECTION DIELECTRIC SLAB LASER-BEAM DISPLACEMENT METAMATERIALS CONFIGURATION

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Scanning error detection and compensation algorithm for white-light interferometry

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OPTICS AND LASERS IN ENGINEERING 2022年 148卷 106768-106768页

作者： Cui, Kaihua Liu, Qian Huang, Xiaojin Zhang, Hui Li, Lulu China Acad Engn Phys Inst Machinery Mfg Technol 64th Mianshan Rd Mianyang 621000 Sichuan Peoples R China

As the primary error source in white-light interferometry (WLI), the error of scanning steps directly affects coherence peak sensing and greatly lowers the measurement accuracy. Based on the least-squares iterative algorithm, we present an algorithm to detect and compensate for scanning error in WLI. The actual scanning step is calculated from the continuous moving fringes with an iterative algorithm, and the surface is reconstructed with the calculated scanning steps to make compensation. Both simulations and experiments indicate that the high-accuracy measurements can be implemented under disturbance over a wide frequency band. The proposed algorithm could relax the environment requirement of white-light interferometer application.

关键词： White-light interferometry Surface topography measurement Vibration resistance iterative algorithm

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Fast algorithm and Its Application in Construction Monitoring of Parallel Strand Cables

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JOURNAL OF BRIDGE ENGINEERING 2015年第9期20卷 04014100-04014100页

作者： Wang, Ronghui Zhang, Zhuojie Dong, Chunguang Huang, Yonghui S China Univ Technol Sch Civil Engn & Transportat State Key Lab Subtrop Bldg Sci Guangzhou 510640 Guangdong Peoples R China S China Univ Technol Sch Civil Engn & Transportat Guangzhou 510640 Guangdong Peoples R China Guangzhou Univ Guangzhou Univ Tamkang Univ Joint Res Ctr Engn St Guangzhou 510006 Guangdong Peoples R China

A fast algorithm for determining the installation force of parallel strand cables is proposed in this paper. Because cable-stayed bridges are flexible structures, the algorithm must consider the sag effect of cable stays as well as the prestressing loss caused by displacements of the deck and the pylon when erecting stay cables with a strand-by-strand method. Based on the principle of the isotension method for parallel strand cables, two basic problems involved in the stretching process and the corresponding numerical computing method are fully demonstrated in this paper. To consider the nonlinearity of cables, catenary theory is used for determining the cable shape and cable forces during the entire loading process. According to said method, a corresponding calculation program was compiled, followed by an additional error analysis. Case studies are provided to compare the results calculated by the program with data measured from an ongoing road-rail cable-stayed bridge and from other calculation methods. The results confirm that this computing method can ensure both efficiency and accuracy and is equally applicable to the problem of cable replacement. (C) 2014 American Society of Civil Engineers.

关键词： Parallel strand cables Cable force iterative algorithm Numerical method

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Numerical simulation for train-track-bridge dynamic interaction considering damage constitutive relation of concrete tracks

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ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING 2021年第3期21卷 116-116页

作者： Xu, Lei Yu, Zhiwu Shan, Zhi Cent South Univ Sch Civil Engn Shaoshan Rd 22 Changsha 410075 Peoples R China Natl Engn Lab High Speed Railway Construct Changsha 410075 Peoples R China

In this work, a novel and practical method is developed to depict the track slab damage and residual strain evolution, where the concrete damage constitutive relation of track slabs is considered within the train-track-bridge dynamics framework. A three-step strain method is presented to judge the load/unloading, compression/tension status of track slab elements ergodically, so that the damage condition and residual strain of track slabs can be determined. To improve the computational accuracy and efficiency, the combination of the matrix augment method and iterative solution algorithm is elucidated in detail. To validate the present model, the solutions among incremental solution, iterative solution, and non-iterative solution are firstly illustrated, and then experimental studies are performed to declare the effectiveness of this model in characterising strain/stress relation of concrete no matter in compression state or in tension state, and finally, other model results are also introduced to prove the effectiveness of this model. In the numerical studies, the damage distributions of track slabs in the longitudinal and lateral direction are presented, where the influence of track irregularities and track slab positions on the bridge is clarified, besides, the evolution of the damage and residual strain of a track slab subject to a moving train is revealed.

关键词： Train-track-bridge dynamic interaction Damage constitutive relation Stress strain status iterative algorithm

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Adaptive Box-Constrained Total Variation Image Restoration Using iterative Regularization Parameter Adjustment Method

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INTERNATIONAL JOURNAL OF PATTERN RECOGNITION AND ARTIFICIAL INTELLIGENCE 2015年第7期29卷 1554003-1554003页

作者： Zhu, Zhining Cai, Guangcheng Wen, You-Wei Kunming Univ Sci & Technol Dept Math Kunming Yunan Peoples R China

In this paper, we consider the problem of image restoration with box-constraints. Image restoration problem is ill-conditioned and the regularization approach has widely been used to stabilize the solution. The restored image highly depends on the choice of the regularization parameter. The regularization parameter is generally determined by trial-and-error method when no true original image is available. Obviously, it is time consuming. The main aim in this paper is to develop an algorithm to choose the regularization parameter automatically when the box-constraints are imposed. In the proposed algorithm, the regularization parameter is adaptively determined by the previous iterative solution. Numerical simulations are used to demonstrate the performance of the proposed method.

关键词： Regularization parameter box-constraints total variation iterative algorithm primal-dual

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INTEGRATED STRUCTURAL-ANALYSIS AND DESIGN USING 3-DIMENSIONAL FINITE-ELEMENTS

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AIAA JOURNAL 1991年第5期29卷 791-797页

作者： BARTHELEMY, B HAFTKA, RT MADAPUR, U SANKARANARAYANAN, S VIRGINIA POLYTECH INST & STATE UNIV DEPT AEROSP & OCEAN ENGNBLACKSBURGVA 24061

A design approach that combines iterative structural analysis with a traditional iterative optimization algorithm is applied to the optimum design of the shape of a hole in a plate in tension. The plate is modeled by three-dimensional finite elements, and an element-by-element preconditioned conjugate gradient iterative algorithm is used for solving the equations of equilibrium. Several parameterizations of the optimum shape are considered, and it is shown that a sine series can describe the optimum shape with only three design variables, whereas other series require seven variables for similar results. The optimum shape compares well with an experimental optimum obtained by A. J. Durelli. An investigation is performed to determine the best way of obtaining finite-difference derivatives of the stresses with respect to design variables. It is shown that a method based on modifying the equations of equilibrium for the perturbed problem performs best. The benefit of the integrated approach is determined by comparing convergence with different initial iterates for the displacement field. It is shown that using the final iterate of the previous solution can reduce the number of analysis iterations by about 40% compared to starting with a zero initial iterate.

关键词： Structural Analysis Optimization algorithm iterative algorithm Finite Element Modeling Gaussian Elimination iterative Solution Structural Optimization Sequential Linear Programming Interlaminar Stress Stress Concentration

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