检索结果-内蒙古大学图书馆

An inverse geometric problem: Position and shape identification of inclusions in a conductor domain

ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS 2013年第11期37卷 1392-1400页

作者： Peters, F. C. Barra, L. P. S. COPPE UFRJ Dept Civil Engn BR-21941972 Rio De Janeiro RJ Brazil Univ Fed Juiz de Fora BR-36036330 Juiz De Fora MG Brazil

This work presents a methodology for identifying inclusions in a conductor domain. The methodology is based on electrical potential measurements on the external boundary of a conductor body subjected to a prescribed set of electrical current injections. The boundary of each inclusion is approximated by a special kind of spline, whose control points have an extra parameter related to the distance between the control point and the curve. Such special feature allows identification of smooth or sharp inclusions with the same initial guess. The identification is an inverse problem that, in this work, is solved by the Levenberg-Marquardt Method. This iterative method tries to locate the minimum of an objective function, the square of the norm of a residual vector function, given by the differences between electrical potential measurements and the computed ones. The computation of the electrical potential is called forward problem and it is solved by an implementation of the direct formulation of the Boundary Element Method (BEM). The present paper addresses two approaches for computing the derivatives of the residual function with respect to the minimization parameters, required by the Levenberg-Marquardt Method. The first one is based on finite differences and the second one is based on the direct differentiation of the integral equation of the BEM for potential problems. Performance comparisons of these two approaches are presented, based on numerical experiments of identification of inclusions with noisy datasets computationally obtained. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Inverse problems Boundary elements optimization algorithms Sensitivity equations

来源：评论

学校读者我要写书评

暂无评论

Spherical Mesh Adaptive Direct Search for Separating Quasi-Uncorrelated Sources by Range-Based Independent Component Analysis

引用

NEURAL COMPUTATION 2013年第9期25卷 2486-2522页

作者： Selvan, S. Easter Borckmans, Pierre B. Chattopadhyay, A. Absil, P. -A. Catholic Univ Louvain ICTEAM Inst Dept Engn Math B-1348 Louvain Belgium Univ Leeds Sch Comp Leeds LS2 9JT W Yorkshire England

It is seemingly paradoxical to the classical definition of the independent component analysis (ICA), that in reality, the true sources are often not strictly uncorrelated. With this in mind, this letter concerns a framework to extract quasi-uncorrelated sources with finite supports by optimizing a range-based contrast function under unit-norm constraints (to handle the inherent scaling indeterminacy of ICA) but without orthogonality constraints. Albeit the appealing contrast properties of the range-based function (e.g., the absence of mixing local optima), the function is not differentiable everywhere. Unfortunately, there is a dearth of literature on derivative-free optimizers that effectively handle such a nonsmooth yet promising contrast function. This is the compelling reason for the design of a nonsmooth optimization algorithm on a manifold of matrices having unit-norm columns with the following objectives: to ascertain convergence to a Clarke stationary point of the contrast function and adhere to the necessary unit-norm constraints more naturally. The proposed nonsmooth optimization algorithm crucially relies on the design and analysis of an extension of the mesh adaptive direct search (MADS) method to handle locally Lipschitz objective functions defined on the sphere. The applicability of the algorithm in the ICA domain is demonstrated with simulations involving natural, face, aerial, and texture images.

关键词： Spherical Adaptive Quasi-Uncorrelated direct search GRAIN PATTERN Sphericity Independent component analysis CONTRAST FUNCTION islet cell antibody Handles optimization algorithms Self tuning

来源：评论

学校读者我要写书评

暂无评论

A geometric inverse problem identification procedure for detection of cavities

引用

ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS 2013年第11期37卷 1401-1407页

作者： Barra, L. P. S. Telles, J. C. F. Univ Fed Juiz de Fora BR-36036330 Juiz De Fora MG Brazil COPPE UFRJ Dept Civil Engn BR-21941972 Rio De Janeiro RJ Brazil

In this paper the inverse problem of electrical impedance tomography (ELT) in a three dimensional environment is considered. In this technique, electrodes are placed on the external boundary of the body and electrical current is injected by sequentially activating pairs of them while the corresponding potentials are measured. Usually such measures are used in order to solve the nonlinear inverse problem of achieving a two-dimensional image of the conductivity distribution over the cross section of the body. In the problem studied here the goal is to determine the size and position of an existing cavity within a homogeneous medium. The geometrical parameters that describe the cavities are the unknowns of the resulting 3D inverse problem, which is solved by the Levenberg-Marquardt method. Two shapes of geometrical cavities are here considered: spherical and spheroidal. Due to its accuracy and simplicity of mesh generation, the Boundary Element Method (BEM) is used in the solution of the direct problem. In order to evaluate the proposed strategy, numerical experiments are presented varying the position and the shape of the cavity and also the injection-measure protocol used. Since measured data are not currently available, boundary potential measurements have been obtained computationally also using BEM. The sensitivity of the present method in the presence of measurement noise has also been estimated through numerical experiments. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Inverse problems Boundary elements optimization algorithms

来源：评论

学校读者我要写书评

暂无评论

Synthesis of EBG Surfaces Using Evolutionary optimization algorithms

Synthesis of EBG Surfaces Using Evolutionary Optimization Al...

引用

European Conference on Antennas and Propagation

作者： L. Deias G. Mazzarella N. Sirena DIEE - Department of Electrical and Electronic Engineering University of Cagliari DIEE and Consorzio COSMOLAB

In this paper evolutionary computation is applied to the synthesis of planar periodic EBG. We constrained our evolutionary design to the unit cell geometry and used a full-wave MoM to evaluate all individuals. Results... 详细信息

ISBN: (纸本)9781424447534

关键词： optimization algorithms synthesis unit cell design by evolution resonant frequencies Bandwidth Evolutionary evolutionary algorithm full-wave METHOD OF MOMENTS Surfaces

来源：评论

学校读者我要写书评

暂无评论

A RELATIVE MAPPING ALGORITHM

A RELATIVE MAPPING ALGORITHM

引用

26th IEEE Annual Canadian Conference on Electrical and Computer Engineering (CCECE)

作者： Kraut, Jay Univ Manitoba Winnipeg MB R3T 2N2 Canada

ISBN: (纸本)9781479900336;9781479900312

This paper introduces a Relative Mapping Algorithm. This algorithm presents a new way of looking at the SLAM problem that does not use Probability, Iterative Closest Point, or Scan Matching techniques. A map of landmarks is generated by using the average relative location difference between landmarks. This means the algorithm does not use any known, estimated or predicted movement or position data. In addition, the Relative Mapping Algorithm has the capability to identify dynamic landmarks using a binning algorithm. The algorithm is shown to have a fast constant time O(n(a)logn(a)) computation complexity where n(a) is the average quantity of points that are visible. In limiting testing the accuracy of the Relative Mapping Algorithm is shown to be comparable to the Extended Kalman Filter.

关键词： Robot Mapping SLAM optimization algorithms

来源：评论

学校读者我要写书评

暂无评论

A Quantized Consensus Algorithm for a Multi-Agent Assignment Problem

A Quantized Consensus Algorithm for a Multi-Agent Assignment...

引用

IEEE International Conference on Systems, Man, and Cybernetics (SMC)

作者： Fanti, Maria Pia Mangini, Agostino Marcello Pedroncelli, Giovanni Ukovich, Walter Politecn Bari Dept Elect & Informat Engn Bari Italy Univ Trieste Dept Engn Architecture Trieste Italy

ISBN: (纸本)9781479906529

This paper improves a previous result on the multi-agent assignment problem, in which a group of agents has to reach a consensus on an optimal distribution of tasks, under communication and assignment constraints. However, the drawback of the proposed distributed algorithm was that the initial feasible assignment state is given. In this paper we develop a start-up algorithm to find an initial feasible assignment state based on synchronous communications among agents. Moreover, the agents exchange the messages and update autonomously and iteratively the task assignment. Some simulation results prove that the proposed consensus algorithm not only is able to reach a feasible solution but such a solution is close to the optimal one.

关键词： Agents and autonomous systems optimization algorithms Sensor networks

来源：评论

学校读者我要写书评

暂无评论

STRUCTURAL CHANGE QUANTIFICATION IN ROTOR SYSTEMS BASED ON MEASURED RESONANCE AND ANTIRESONANCE FREQUENCIES

STRUCTURAL CHANGE QUANTIFICATION IN ROTOR SYSTEMS BASED ON M...

引用

ASME Turbo Expo: Turbine Technical Conference and Exposition

作者： Wroblewski, Adam C. Pesch, Alexander H. Sawicki, Jerzy T. Cleveland State Univ Ctr Rotating Machinery Dynam & Control RoMaDyC Cleveland OH 44115 USA

ISBN: (纸本)9780791855263

A structural change quantification methodology is proposed in which the magnitude and location of a structural alteration is identified experimentally in a rotor system. The resonance and antiresonance frequencies are captured from multiple frequency response functions and are compared with baseline data to extract frequency shifts due to these features. The resulting expression contains sufficient information to identify the dynamic characteristics of the rotor in both the frequency and spatial domains. A finite element model with carefully selected tunable parameters is iteratively adjusted using a numerical optimization algorithm to determine the source of the structural change. The methodology is experimentally demonstrated on a test rig with a laterally damaged rotor and the frequency response functions are acquired through utilization of magnetic actuators positioned near the ball bearings.

关键词： Ball bearings Resonance optimization algorithms Finite element model Actuators Antiresonance Frequency response Rotors

来源：评论

学校读者我要写书评

暂无评论

Differential-algebraic Equations Model for Quadratic Programming

Differential-algebraic Equations Model for Quadratic Program...

引用

9th International Conference on Computational Intelligence and Security (CIS)

作者： Yang, Yajuan Zhang, Quanju Dongguan Univ Technol City Coll Financial Dept Dongguan Guangdong Peoples R China Dongguan Univ Technol City Coll Dept Management Dongguan Guangdong Peoples R China

ISBN: (纸本)9781479925483

A differential-algebraic equations (DAEs) model for solving convex quadratic programming (CQP) is studied in this paper. By using Frisch's logarithmic barrier function, the DAEs model is established and the corresponding relationships of the solutions to the proposed DAEs with the CQP problems is analyzed in details here. All the results shows that this new model is different from traditional optimization algorithms which tries to find optimal solutions by the classical discrete iterated sequence points as well as different from neural network method based on the ODEs which tries to find the optimal solutions by tracking trajectories of a set of ordinary differential equation systems. It is well-known that different numerical schemes to DAEs algorithm can lead to new algorithms or some classical iterated algorithms, for instance, the path-following interior point algorithm could be conducted by a scheme of the proposed DAEs algorithm. So, in this aspect, the conventional interior point method can be viewed as a special case of the new DAEs method. Hence, this DAEs model provides a promising alternative approach for solving convex quadratic programming problems

关键词： quadratic programming optimal solution differential algebraic equations optimization algorithms Interior point algorithm differential equation system Ordinary differential equation trees (mathematics) trajectory tracking

来源：评论

学校读者我要写书评

暂无评论

On Flow Level Modeling of Multi-Cell Wireless Networks

On Flow Level Modeling of Multi-Cell Wireless Networks

引用

11th International Symposium and Workshops on Modeling and optimization in Mobile, Ad Hoc and Wireless Networks (WiOpt)

作者： Fehske, Albrecht J. Fettweis, Gerhard P. Tech Univ Dresden Vodafone Stiftungslehrstuhl Dresden Germany

ISBN: (纸本)9781612848242

In order to meet increasing traffic demands, future generations of cellular networks are characterized by decreasing cell sizes at full frequency reuse. Due to inevitable inter-cell interference, load conditions in neighboring cells can no longer be considered independent. This paper provides a flow level modeling framework for cellular networks, where the coupling of flow level dynamics due to intercell interference is specifically taken into account. Since an adequate queueing model renders analytically intractable, we review different methods from the literature to bound and approximate the stationary behavior of network performance measures. Numerical investigations of a typical wireless scenario reveal, that in high and low load regimes first as well as second order bounds may be quite loose, depending on the type of bound. Especially for design of network optimization algorithms, bounds do not appear to suitably reflect network performance, and approximation techniques must be considered instead. In this regard, a suitable tradeoff between computational complexity and accuracy over the whole traffic range is provided by a model based on the notion of average interference.

关键词： Wireless networks Cellular networks inter-cell interference Bound optimization algorithms frequency reuse wireless multi-hop networks Network design complexity classes Modeling

来源：评论

学校读者我要写书评

暂无评论

COMPUTER-AIDED IDENTIFICATION OF AGRO-FOOD AND FOREST PRODUCT PROPERTIES FOR HEAT AND WATER TRANSPORT SIMULATIONS

COMPUTER-AIDED IDENTIFICATION OF AGRO-FOOD AND FOREST PRODUC...

引用

5th International Conference on Trends in Agricultural Engineering

作者： Weres, Jerzy Olek, Wieslaw Kujawa, Sebastian Siatkowski, Michal Poznan Univ Life Sci Dept Appl Informat Inst Biosyst Engn PL-60637 Poznan Poland

ISBN: (纸本)9788021323889

It is difficult to represent properties of agro-food and forest products in mathematical models to simulate heat and water transport processes. Geometry of such products is complex, material structure is non-homogeneous and anisotropic, and properties vary with temperature and moisture content. Heat and water transport processes affect the end-use quality of agro-food and forest products, so it is important to support design and management of advanced systems of processing and storage of such products with mathematical modelling and computer predictions. In the paper an integrated computer-aided approach to estimate geometric and physical properties of agro-food and forest products was developed. The method was effective and it resulted in more accurate predictions of heat and water transport processes in investigated products.

关键词： image analysis geometry measurement geometry modeling finite element algorithms optimization algorithms software development

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：