检索结果-内蒙古大学图书馆

Image reconstruction technique of electrical capacitance tomography for low-contrast dielectrics using Calderon's method

引用

MEASUREMENT SCIENCE AND TECHNOLOGY 2009年第10期20卷 104027 (12-104027 (12页

作者： Cao, Zhang Xu, Lijun Wang, Huaxiang Beihang Univ Sch Instrumentat & Optoelect Engn Beijing 100191 Peoples R China Tianjin Univ Sch Elect Engn & Automat Tianjin 300072 Peoples R China

Calderon's method was introduced to electrical capacitance tomography in this paper. It is a direct algorithm of the image reconstruction for low-contrast dielectrics, as no matrix inversion or iterative process is needed. It was implemented through numerical integration. Since the Gauss-Legendre quadrature was applied and can be predetermined, the image reconstruction process was fast and resulted in images of high quality. Simulations were carried out to study the effect of different dielectric contrasts and different electrode numbers. Both simulated and experimental results validated the feasibility and effectiveness of Calderon's method in electrical capacitance tomography for low-contrast dielectrics.

关键词： Calderon's method electrical capacitance tomography direct algorithm

来源：评论

学校读者我要写书评

暂无评论

An efficient global optimization algorithm for multifactor dynamic systems

引用

JOURNAL OF THE CHINESE INSTITUTE OF ENGINEERS 2008年第6期31卷 933-941页

作者： Tsai, Chih-Ming Wang, Nenzi Chang Gung Univ Dept Mech Engn Tao Yuan 333 Taiwan

In this study we present an efficient global optimization method. DIviding RECTangle (direct) algorithm, for parametric analysis of dynamic systems. In a bounded constrained problem the direct algorithm explores multiple potentially optimal subspaces in one search. The algorithm also eliminates the need for derivative calculations which are required in some efficient gradient-based methods. In this Study the first optimization example is to find the dynamic parameters of a tennis racket. The second example is a biomechanical parametric study of a heel-toe running, model Governed by six factors. The effectiveness of the direct algorithm is compared with a genetic algorithm in an analysis of heel-toe running. The result shows that the direct algorithm obtains an improved result in 83% less execution time. It is demonstrated that the straightforward direct algorithm provides a general procedure for solving global optimization problems efficiently and confidently.

关键词： nonlinear least squares heel-toe running direct algorithm genetic algorithm

来源：评论

学校读者我要写书评

暂无评论

Multivariable Electromagnetic Optimization Design Exploiting Hybrid Kriging

引用

COMPUTING IN SCIENCE & ENGINEERING 2019年第5期21卷 46-54页

作者： Xiao, Song Zhang, Kunlun Liu, Guoqing Wang, Ying Duan, Jiaheng Kong, Lingxing Southwest Jiaotong Univ Sch Elect Engn Chengdu Sichuan Peoples R China Southwest Jiaotong Univ Chengdu Sichuan Peoples R China

Electromagnetic optimization utilizing finite element or similar numerical techniques always carries a heavy burden of computation;therefore, an efficient optimizer reducing the number of objective function calls to find the optimum accurately is essential. Kriging as a regression model is able to locate the optimum;meanwhile, it also can produce the response surface of objective function only based on the spatial correlation of limited information. However, the storage of correlation matrices generated by a kriging optimizer, along with the iterative optimization process, is an issue in the context of the electromagnetic optimization problems with many design variables and multiple optimal objectives. The proposed hybrid kriging methodology incorporating a direct algorithm is able to maintain memory occupation of the optimizer as a nearly constant level. It performs efficiently and reliably while coping with the large-scale multivariable optimization tasks. The feasibility and efficiency of the proposed hybrid kriging are verified via a classic analytic function and the multivariable benchmark TEAM Workshop problem 22.

关键词： Electromagnetic Devices Finite Element Analysis Iterative Methods Matrix Algebra Optimisation Regression Model Correlation Matrices Kriging Optimizer Iterative Optimization Process Electromagnetic Optimization Problems Hybrid Kriging Methodology Multivariable Benchmark TEAM Workshop Problem Multivariable Electromagnetic Optimization Design Large Scale Multivariable Optimization Finite Element Electromagnetics Optimization Magnetic Levitation Linear Programming Suspensions algorithm Design And Analysis Computational Modeling Kriging Correlation Matrices Hybrid Kriging direct algorithm Benchmark TEAM Workshop Problem 22

来源：评论

学校读者我要写书评

暂无评论

Determination of heliostat canting errors via deterministic optimization

引用

SOLAR ENERGY 2017年 150卷 136-146页

作者： Sanchez-Gonzalez, Alberto Caliot, Cyril Ferriere, Alain Santana, Domingo Univ Carlos III Madrid Dept Thermal & Fluid Engn Av Univ 30 Madrid 28911 Spain PROMES CNRS Proc Mat & Solar Energy Lab 7 Rue Four Solaire F-66120 Font Romeu Odeillo Via France

This paper presents a novel methodology to find out canting errors in the facets, i.e. mirror modules, of heliostats. An optimization procedure is established to fit simulated heliostat flux distributions to those captured on a white target. On the basis of a convolution-projection optical model, a deterministic algorithm - named direct - has been successfully implemented, reaching correlation coefficients up to 95.8%. In this instance, the procedure has been applied to a THEMIS heliostat presenting canting errors of its, faceted modules. From the optimization results, the heliostat modules were accordingly readjusted. And the heliostat optical quality has been significantly increased, validating the proposed methodology. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： Solar power tower Heliostat optical quality Flux distribution direct algorithm

来源：评论

学校读者我要写书评

暂无评论

Electrical Capacitance Tomography for Sensors of Square Cross Sections Using Calderon's Method

引用

IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2011年第3期60卷 900-907页

作者： Cao, Zhang Xu, Lijun Fan, Wenru Wang, Huaxiang Beihang Univ Sch Instrumentat & Optoelect Engn Beijing 100191 Peoples R China Tianjin Univ Sch Elect Engn & Automat Tianjin 300072 Peoples R China

Calderon's method was generalized to electrical capacitance tomography (ECT) for sensors of square cross sections in this paper. It is a direct algorithm of image reconstruction, as neither matrix inversion nor an iterative process is required for image reconstruction. Since the major calculations are implemented in terms of a circular region, complicated calculations required by Calderon's method for a noncircular cross section are avoided. A unique conformal transformation was used to establish a map from a circular region to a square. Results were obtained for a sensor of square cross section by using the conformal transformation. Two approximations of the scattering transform used in Calderon's method were compared with simulated data. The Gauss-Legendre quadrature was applied to provide a fast-speed and high-quality image reconstruction. The reconstructed results validated the feasibility and effectiveness of the proposed treatment of Calderon's method in ECT with a sensor of noncircular cross section.

关键词： Calderon's method conformal transformation direct algorithm electrical capacitance tomography (ECT) square cross section

来源：评论

学校读者我要写书评

暂无评论

Analysis of the self-excited induction generator steady state performance using a new efficient algorithm

引用

ELECTRIC POWER SYSTEMS RESEARCH 2012年 86卷 61-67页

作者： Kheldoun, Aissa Refoufi, Larbi Khodja, Djalal Eddine Univ Boumerdes Inst Elect & Elect Engn Signals & Syst Lab Boumerdes Algeria

The paper presents the application of direct algorithm to analyse the performance of the Self-excited induction generator (SEIG). To the author best knowledge, this is the first attempt to apply it to such a problem. direct algorithm is used to minimize the induction generator's admittance without the need to separate it into its real and imaginary parts. No initial guess is required as it needs only the upper and lower values of the unknown variables which are easily determined. The obtained minimum admittance yields the adequate magnetizing reactance and the frequency. These two key parameters are then used to compute the self-excitation process requirements in terms of the prime mover speed, the capacitance and the load impedance on the one hand and to predict the generator steady state performance parameters on the other. Very good agreement between predicted results and experimental measurements is achieved. (C) 2011 Elsevier B.V. All rights reserved.

关键词： Induction generator Optimisation direct algorithm Self-excitation

来源：评论

学校读者我要写书评

暂无评论

Design of zero reference codes by means of a global optimization method

引用

OPTICS EXPRESS 2005年第1期13卷 195-201页

作者： Saez-Landete, J Alonso, J Bernabeu, E Univ Complutense Fac Ciencias Fis Dept Opt E-28040 Madrid Spain

The grating measurement systems can be used for displacement and angle measurements. They require of zero reference codes to obtain zero reference signals and absolute measures. The zero reference signals are obtained from the autocorrelation of two identical zero reference codes. The design of codes which generate optimum signals is rather complex, especially for larges codes. In this paper we present a global optimization method, a direct algorithm for the design of zero reference codes. This method proves to be a powerful tool for solving this inverse problem. (C) 2005 Optical Society of America.

关键词： .optimum autocorrelation Lipschitz Global Optimization reference codes direct algorithm

来源：评论

学校读者我要写书评

暂无评论

Structural damage identification using piezoelectric impedance measurement with sparse inverse analysis

引用

SMART MATERIALS AND STRUCTURES 2018年第3期27卷 035020-035020页

作者： Cao, Pei Qi, Shuai Tang, J. Univ Connecticut Dept Mech Engn Storrs CT 06269 USA Chongqing Univ Dept Automot Engn Chongqing 400044 Peoples R China

The impedance/admittance measurements of a piezoelectric transducer bonded to or embedded in a host structure can be used as damage indicator. When a credible model of the healthy structure, such as the finite element model, is available, using the impedance/admittance change information as input, it is possible to identify both the location and severity of damage. The inverse analysis, however, may be under-determined as the number of unknowns in high-frequency analysis is usually large while available input information is limited. The fundamental challenge thus is how to find a small set of solutions that cover the true damage scenario. In this research we cast the damage identification problem into a multi-objective optimization framework to tackle this challenge. With damage locations and severities as unknown variables, one of the objective functions is the difference between impedance-based model prediction in the parametric space and the actual measurements. Considering that damage occurrence generally affects only a small number of elements, we choose the sparsity of the unknown variables as another objective function, deliberately, the l(0) norm. Subsequently, a multi-objective Dividing RECTangles (direct) algorithm is developed to facilitate the inverse analysis where the sparsity is further emphasized by sigmoid transformation. As a deterministic technique, this approach yields results that are repeatable and conclusive. In addition, only one algorithmic parameter, the number of function evaluations, is needed. Numerical and experimental case studies demonstrate that the proposed framework is capable of obtaining high-quality damage identification solutions with limited measurement information.

关键词： damage identification piezoelectric impedance/admittance inverse analysis sparse regularization multi-objective optimization direct algorithm l(0) norm

来源：评论

学校读者我要写书评

暂无评论

Globally-biased DISIMPL algorithm for expensive global optimization

引用

JOURNAL OF GLOBAL OPTIMIZATION 2014年第2-3期59卷 545-567页

作者： Paulavicius, Remigijus Sergeyev, Yaroslav D. Kvasov, Dmitri E. Zilinskas, Julius Vilnius State Univ Inst Math & Informat LT-08663 Vilnius Lithuania Univ Calabria Dipartimento Ingn Informat Modellist Elettron & S Via P BucciCubo 42C I-87036 Arcavacata Di Rende CS Italy NI Lobachevsky State Univ Software Dept Nizhnii Novgorod Russia

direct-type global optimization algorithms often spend an excessive number of function evaluations on problems with many local optima exploring suboptimal local minima, thereby delaying discovery of the global minimum. In this paper, a globally-biased simplicial partition Disimpl algorithm for global optimization of expensive Lipschitz continuous functions with an unknown Lipschitz constant is proposed. A scheme for an adaptive balancing of local and global information during the search is introduced, implemented, experimentally investigated, and compared with the well-known direct and direct l methods. Extensive numerical experiments executed on 800 multidimensional multiextremal test functions show a promising performance of the new acceleration technique with respect to competitors.

关键词： Global optimization Lipschitz condition direct algorithm Two-phase approach Globally-biased DISIMPL algorithm

来源：评论

学校读者我要写书评

暂无评论

An approach to constrained global optimization based on exact penalty functions

引用

JOURNAL OF GLOBAL OPTIMIZATION 2012年第2期54卷 251-260页

作者： Di Pillo, G. Lucidi, S. Rinaldi, F. Univ Roma La Sapienza Dipartimento Informat & Sistemist I-00185 Rome Italy

In the field of global optimization many efforts have been devoted to solve unconstrained global optimization problems. The aim of this paper is to show that unconstrained global optimization methods can be used also for solving constrained optimization problems, by resorting to an exact penalty approach. In particular, we make use of a non-differentiable exact penalty function . We show that, under weak assumptions, there exists a threshold value of the penalty parameter such that, for any , any global minimizer of P (q) is a global solution of the related constrained problem and conversely. On these bases, we describe an algorithm that, by combining an unconstrained global minimization technique for minimizing P (q) for given values of the penalty parameter and an automatic updating of that occurs only a finite number of times, produces a sequence {x (k) } such that any limit point of the sequence is a global solution of the related constrained problem. In the algorithm any efficient unconstrained global minimization technique can be used. In particular, we adopt an improved version of the direct algorithm. Some numerical experimentation confirms the effectiveness of the approach.

关键词： Nonlinear programming Global optimization Exact penalty functions direct algorithm

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：