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Existence and iterative algorithm of solutions for a system of generalized set-valued strongly nonlinear mixed variational-like inequalities problems in Banach spaces

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JOURNAL OF APPLIED MATHEMATICS AND COMPUTING 2010年第1-2期33卷 209-225页

作者： Wang, Zhong Bao Ding, Xie Ping Sichuan Univ Coll Math Chengdu 610064 Sichuan Peoples R China Sichuan Normal Univ Coll Math & Software Sci Chengdu 610066 Sichuan Peoples R China

In this paper, we introduce and study a new system of generalized set-valued strongly nonlinear mixed variational-like inequalities problems and its related auxiliary problems in reflexive Banach spaces. The auxiliary principle technique is applied to study the existence and iterative algorithm of solutions for the system of generalized set-valued strongly nonlinear mixed variational-like inequalities problems. Firstly, we prove the existence and uniqueness of solutions of the auxiliary problems for the system of generalized set-valued strongly nonlinear mixed variational-like inequalities problems. Secondly, an iterative algorithm for solving the system of generalized set-valued strongly nonlinear mixed variational-like inequalities problems is constructed by using this existence and uniqueness result. Finally, we show the existence of solutions of the system of generalized set-valued strongly nonlinear mixed variational-like inequalities problems and discuss the convergence analysis of this algorithm. These results improve, unify and generalize many corresponding known results given in literatures.

关键词： System of generalized set-valued strongly nonlinear mixed variational-like inequalities problems Auxiliary principle iterative algorithm Reflexive Banach spaces

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An iterative algorithm for a least squares solution of a matrix equation

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INTERNATIONAL JOURNAL OF COMPUTER MATHEMATICS 2010年第6期87卷 1289-1298页

作者： Wang, Minghui Wei, Musheng Feng, Yan Qufu Normal Univ Dept Math Qufu 273165 Shandong Peoples R China Shanghai Normal Univ Sci Comp Key Lab Shanghai Univ Dept Math Shanghai 200234 Peoples R China Qingdao Univ Sci & Technol Coll Informat Qingdao 266061 Peoples R China

In this article, we propose an iterative algorithm to compute the minimum norm least-squares solution of AXB + CYD = E, based on a matrix form of the algorithm LSQR for solving the least squares problem. We then apply this algorithm to compute the minimum norm least-squares centrosymmetric solution of min(X) parallel to AXB - E parallel to(F). Numerical results are provided to verify the efficiency of the proposed method.

关键词： matrix equation centrosymmetric matrix least squares problem LSQR 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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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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algorithm-enabled exploration of image-quality potential of cone-beam CT in image-guided radiation therapy

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PHYSICS IN MEDICINE AND BIOLOGY 2015年第12期60卷 4601-4633页

作者： Han, Xiao Pearson, Erik Pelizzari, Charles Al-Hallaq, Hania Sidky, Emil Y. Bian, Junguo Pan, Xiaochuan Univ Chicago Dept Radiol Chicago IL 60637 USA Univ Chicago Dept Radiat & Cellular Oncol Chicago IL 60637 USA Massachusetts Gen Hosp Dept Radiol Boston MA 02114 USA

Kilo-voltage (KV) cone-beam computed tomography (CBCT) unit mounted onto a linear accelerator treatment system, often referred to as on-board imager (OBI), plays an increasingly important role in image-guided radiation therapy. While the FDK algorithm is currently used for reconstructing images from clinical OBI data, optimization-based reconstruction has also been investigated for OBI CBCT. An optimization-based reconstruction involves numerous parameters, which can significantly impact reconstruction properties (or utility). The success of an optimization-based reconstruction for a particular class of practical applications thus relies strongly on appropriate selection of parameter values. In the work, we focus on tailoring the constrained-TVminimization- based reconstruction, an optimization-based reconstruction previously shown of some potential for CBCT imaging conditions of practical interest, to OBI imaging through appropriate selection of parameter values. In particular, for given real data of phantoms and patient collected with OBI CBCT, we first devise utility metrics specific to OBI-quality-assurance tasks and then apply them to guiding the selection of parameter values in constrained-TV-minimization-based reconstruction. The study results show that the reconstructions are with improvement, relative to clinical FDK reconstruction, in both visualization and quantitative assessments in terms of the devised utility metrics.

关键词： cone-beam CT image reconstruction optimization iterative algorithm

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Sparse-view proton computed tomography using modulated proton beams

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MEDICAL PHYSICS 2015年第2期42卷 1129-1137页

作者： Lee, Jiseoc Kim, Changhwan Min, Byungjun Kwak, Jungwon Park, Seyjoon Lee, Se Byeong Park, Sungyong Cho, Seungryong Korea Adv Inst Sci & Technol Dept Nucl & Quantum Engn Taejon 305701 South Korea Kangbuk Samsung Hosp Dept Radiat Oncol Seoul 110746 South Korea Asan Med Ctr Dept Radiat Oncol Asan 138736 South Korea Natl Canc Ctr Proton Therapy Ctr Seoul 410769 South Korea McLaren Canc Inst Proton Therapy Ctr Flint MI 48532 USA

Purpose: Proton imaging that uses a modulated proton beam and an intensity detector allows a relatively fast image acquisition compared to the imaging approach based on a trajectory tracking detector. In addition, it requires a relatively simple implementation in a conventional proton therapy equipment. The model of geometric straight ray assumed in conventional computed tomography (CT) image reconstruction is however challenged by multiple-Coulomb scattering and energy straggling in the proton imaging. Radiation dose to the patient is another important issue that has to be taken care of for practical applications. In this work, the authors have investigated iterative image reconstructions after a deconvolution of the sparsely view-sampled data to address these issues in proton CT. Methods: Proton projection images were acquired using the modulated proton beams and the EBT2 film as an intensity detector. Four electron-density cylinders representing normal soft tissues and bone were used as imaged object and scanned at 40 views that are equally separated over 360 degrees. Digitized film images were converted to water-equivalent thickness by use of an empirically derived conversion curve. For improving the image quality, a deconvolution-based image deblurring with an empirically acquired point spread function was employed. They have implemented iterative image reconstruction algorithms such as adaptive steepest descent-projection onto convex sets (ASD-POCS), superiorization method-projection onto convex sets (SM-POCS), superiorization method-expectation maximization (SM-EM), and expectation maximization-total variation minimization (EM-TV). Performance of the four image reconstruction algorithms was analyzed and compared quantitatively via contrast-to- noise ratio (CNR) and root-mean-square-error (RMSE). Results: Objects of higher electron density have been reconstructed more accurately than those of lower density objects. The bone, for example, has been reconstructed

关键词： proton computed tomography modulated proton beam image reconstruction iterative algorithm

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Incremental Path Repair in Hierarchical Motion-Planning with Dynamical Feasibility Guarantees for Mobile Robotic Vehicles

Incremental Path Repair in Hierarchical Motion-Planning with...

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European Control Conference (ECC)

作者： Zhang, Zetian Cowlagi, Raghvendra V. Worcester Polytech Inst Aerosp Engn Program Worcester MA 01609 USA

ISBN: (纸本)9783952426937

New requirements of autonomous mobile vehicles necessitate hierarchical motion-planning techniques that not only find a plan to satisfy high-level specifications, but also guarantee that this plan is suitable for execution under vehicle dynamical constraints. In this context, the H-cost motion planning technique has been reported in the recent literature. We propose an incremental motion-planning algorithm based on this technique. The proposed algorithm retains the benefits of the original technique, while significantly reducing the associated computational time. In particular, the proposed iterative algorithm presents during intermediate iterations feasible solutions, with the guarantee that the algorithm eventually converges to an optimal solution. The costs of solutions at intermediate iterations are almost always nonincreasing. Therefore, the proposed algorithm is suitable for real-time implementations, where hard bounds on the available computation time are imposed, and where the original H-cost optimization algorithm may not have sufficient time to converge to a solution at all. We illustrate the proposed algorithm with numerical simulation examples.

关键词： iterative methods mobile robots optimisation path planning H-cost motion-planning technique H-cost optimization algorithm autonomous mobile vehicles dynamical feasibility guarantees hierarchical motion-planning incremental motion-planning algorithm incremental path repair iterative algorithm mobile robotic vehicles vehicle dynamical constraints Atmospheric modeling Cost function History Planning Real-time systems Trajectory Vehicles

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Terahertz Phase Image Reconstruction Using an iterative algorithm

Terahertz Phase Image Reconstruction Using an Iterative Algo...

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35th International Conference on Infrared, Millimeter and Terahertz Waves

作者： Wang, Yingxin Chen, Zhiqiang Zhao, Ziran Zhang, Li Kang, Kejun Deng, Jingkang Tsinghua Univ Dept Phys Beijing 100084 Peoples R China Tsinghua Univ Minist Educ Key Lab Particle & Radiat Imaging Beijing Peoples R China Tsinghua Univ Dept Engn Phys Beijing Peoples R China

ISBN: (纸本)9781424466573

We present a terahertz phase contrast imaging technique based on the iterative phase retrieval method which can be realized readily on the conventional terahertz intensity measurement system. The complex wave field of terahertz radiation in the object plane (i.e., the terahertz phase image) is reconstructed from its measured Fourier transform magnitude using the Gerchberg-Saxton-Fienup algorithm with a known object support constraint. Preliminary experimental tests for a nearly transparent sample are performed to demonstrate the feasibility of this new imaging concept.

关键词： Fourier transform magnitude Gerchberg-Saxton-Fienup algorithm image reconstruction intensity measurement iterative algorithm iterative methods iterative phase retrieval method terahertz intensity measurement system terahertz phase contrast imaging technique terahertz phase image reconstruction terahertz wave imaging

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Improvement of the iterative algorithm for Numerical Simulation of Springback in Sheet Metal Forming

Improvement of the Iterative Algorithm for Numerical Simulat...

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Global Conference on Digital Design and Manufacturing Technology

作者： Han, Jun Shi, Fazhong Shao, Likang Beijing Univ Aeronaut & Astronaut Beijing 100083 Peoples R China Artillery Acad PLA Hefei 230031 Peoples R China

ISBN: (纸本)087849278X

Springback is an inevitable process of sheet metal forming phenomenon. Numerical simulation is an effective way to solve the springback problem, and more and more attention to industry and academia. This paper describes the implicit springback analysis of the BFGS equilibrium iteration method, and proposes a strategy for optimizing the calculation, reducing the computation and avoiding the potential problem of instability in the calculation. At last, the use of self-developed software gives numerical examples.

关键词： Sheet metal forming Numerical simulation Springback iterative algorithm

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AN algorithm FOR DESIGNING A DOE TO FORM OPTICAL TRAPS OF A PRESET CONFIGURATION

COMPUTER OPTICS

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COMPUTER OPTICS 2015年第2期39卷 181-186页

作者： Skidanov, R. V. Ganchevskaya, S. V. Samara State Aerosp Univ Russian Acad Sci Image Proc Syst Inst Samara Russia

We proposed an algorithm for calculating a DOE forming vortex beams with a preset distribution of minima and maxima. We discussed several versions of this algorithm. We presented the calculation of some configurations... 详细信息

关键词： calculation of the phase function optical trap iterative algorithm vortex axicon

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