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Numerical simulation based on a combination of finite-element method and proper orthogonal decomposition to prevent the groundwater contamination

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ENGINEERING WITH COMPUTERS 2022年第SUPPL 4期38卷 3445-3461页

作者： Dehghan, Mehdi Hooshyarfarzin, Baharak Abbaszadeh, Mostafa Amirkabir Univ Technol Fac Math & Comp Sci Dept Appl Math 424 Hafez Ave Tehran 15914 Iran

In this paper, the coupled advection-dominated diffusion-reaction equations which arise in the prevention of groundwater contamination problem are approximated by usual finite element method (FEM). It is clear that by increasing the number of elements to improve computational accuracy, we have to incur a lot of costs. The main presented idea is to reduce the used CPU time for employing the finite-element method by combining that with a technique which reduces the dimension of the problem. To this end, we apply the proper orthogonal decomposition (POD) technique to the usual FEM for the prevention of groundwater contamination problem to reduce CPU time with acceptable accuracy. Numerical examples are provided to illustrate efficiency and validity of the proposed method.

关键词： finite-element method Proper orthogonal decomposition Coupled non-linear advection-diffusion-reaction system Prevention of groundwater contamination model

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Buckling analysis of circular functionally graded material plate having variable thickness under uniform compression by finite-element method

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE 2007年第11期221卷 1241-1247页

作者： Naei, M. H. Masoumi, A. Shamekhi, A. Univ Tehran Dept Mech Engn Tehran Iran

The current study presents the buckling analysis of radially-loaded circular plate with variable thickness made of functionally graded material. The boundary conditions of the plate is either simply supported or clamped. The stability equations were obtained using energy method based on Love-Kichhoff hypothesis and Sander's non-linear strain-displacement relation for thin plates. The finite-element method is used to determine the critical buckling load. The results obtained show good agreement with known analytical and numerical data. The effects of thickness variation and Poisson's ratio are investigated by calculating the buckling load. These effects are found not to be the same for simply supported and clamped plates.

关键词： buckling functionally graded materials finite-element method circular plate

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Digital image processing for physical basis analysis of electrical failure forecasting in XLPE power cables based on field simulation using finite-element method

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IET GENERATION TRANSMISSION & DISTRIBUTION 2020年第26期14卷 6703-6714页

作者： Talaat, M. Tayseer, M. El-Zein, A. Zagazig Univ Fac Engn Elect Power & Machines Dept Zagazig Egypt Shaqra Univ Coll Engn Elect Dept Dawadmi Ar Riyadh Saudi Arabia

In this research, digital image processing method (DIPM) is used as an innovative approach to predict precisely the shape of electrical tree (ET) in cross-linked polyethylene (XLPE) power cables in the presence of air voids based on the field calculation using finite-element method (FEM). With the help of DIPM, two case studies are held to detect the accurate parameters of either the first initiated major branch or the tips of the major branches of ET. A hyperbolic needle-to-plane simulation model is proposed to illustrate the ET inception and propagation stages. The non-uniform electric fields thatare accompanied with the electrical treeing phenomenon are calculated using FEM as one of the most effective numerical methods to deal with non-uniform shapes. The predicted shapes of ET initiation and growth are provided in an innovative manner with the implemented hybrid connection between FEM and DIPM for the two proposed case studies. Direction branching approach and deviation angle branching approach are provided in this work to predict the shape and the direction of ET branched voids. The validity of the proposed model is assessed with the help of available previous experimental and simulation data.

关键词： power cables power cable insulation XLPE insulation trees (electrical) finite element analysis voids (solid) finite-element method digital image processing method DIPM electrical tree cross-linked polyethylene power cables air voids field calculation FEM accurate parameters initiated major branch hyperbolic needle-to-plane simulation model propagation stages nonuniform electric fields electrical treeing phenomenon effective numerical methods nonuniform shapes innovative manner deviation angle branching approach available previous experimental simulation data physical basis analysis electrical failure forecasting XLPE power cables field simulation

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A robust a posteriori error estimate for the Fortin-Soulie finite-element method

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COMPUTERS & MATHEMATICS WITH APPLICATIONS 2004年第12期48卷 1863-1876页

作者： Blacker, DJ Univ Strathclyde Dept Math Glasgow G1 1XH Lanark Scotland

The subject of a posteriori error estimation is widely studied, and a variety of such error estimates have been used for elasticity problems in recent years. Of particular interest is the work carried out in [1,2]. In this paper, we derive a new a posteriori error estimator for the quadratic nonconforming Fortin-Soulie element for the error in an energy-like norm. Then, we illustrate the new error bound by presenting some numerical examples, and show an example of a sequence of adaptively refined meshes. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： finite-element method Fortin-Soulie finite element a posteriori error estimation

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Simulation of the orthogonal metal cutting process using an arbitrary Lagrangian-Eulerian finite-element method

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JOURNAL OF MATERIALS PROCESSING TECHNOLOGY 2000年第2期103卷 267-275页

作者： Movahhedy, M Gadala, MS Altintas, Y Univ British Columbia Dept Mech Engn Vancouver BC V6T 1N5 Canada

Two different finite-element formulations, the Lagrangian and the Eulerian, have been used extensively in the modeling of the orthogonal metal cutting process. Each of these formulations has some disadvantages that make it inefficient for modeling the cutting process. In this paper, it is shown that a more general formulation, the arbitrary Lagrangian-Eulerian (ALE) method may be used to combine the advantages and avoid the shortcomings of both of the previous methods. It is also shown that due to the characteristics of the cutting process, this formulation offers the most efficient modeling approach. Some preliminary results of this approach are presented to demonstrate its capabilities and potential in simulating the cutting process. (C) 2000 Elsevier Science S.A. All rights reserved.

关键词： orthogonal metal cutting process ALE finite-element method

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A spline wavelet finite-element method in structural mechanics

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INTERNATIONAL JOURNAL FOR NUMERICAL methodS IN ENGINEERING 2006年第1期66卷 166-190页

作者： Han, JG Ren, WX Huang, Y Cent S Univ Dept Civil Engn Changsha 410075 Peoples R China Hainan Univ Dept Civil Engn Haikou 570228 Peoples R China Xian Univ Architecture & Technol Sch Sci Xian 710055 Peoples R China

The wavelet-based methods are powerful to analyse the field problems with changes in gradients and singularities due to the excellent multi-resolution properties of wavelet functions. Wavelet-based finite elements are often constructed in the wavelet space where field displacements are expressed as a product of wavelet functions and wavelet coefficients. When a complex structural problem is analysed, the interface between different elements and boundary conditions cannot be easily treated as in the case of conventional finite-element methods (FEMs). A new wavelet-based FEM in structural mechanics is proposed in the paper by using the spline wavelets, in which the formulation is developed in a similar way of conventional displacement-based FEM. The spline wavelet functions are used as the element displacement interpolation functions and the shape functions are expressed by wavelets. The detailed formulations of typical spline wavelet elements such as plane beam element, in-plane triangular element, in-plane rectangular element, tetrahedral solid element, and hexahedral solid element are derived. The numerical examples have illustrated that the proposed spline wavelet finite-element formulation achieves a high numerical accuracy and fast convergence rate. Copyright (c) 2005 John Wiley & Sons, Ltd.

关键词： wavelet spline finite-element method wavelet finite-element method interpolation structural mechanics

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Study of Dynamic Impacts on Transmission-Line Systems Attributable to Conductor Breakage Using the finite-element method

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JOURNAL OF PERFORMANCE OF CONSTRUCTED FACILITIES 2011年第2期25卷 130-137页

作者： Shen, Guo-hui Cai, C. S. Sun, Bing-nan Lou, Wen-juan Louisiana State Univ Dept Civil & Environm Engn Baton Rouge LA 70803 USA Zhejiang Univ Dept Civil Engn Hangzhou 310058 Zhejiang Peoples R China

The residual static load (RSL) is defined in the ASCE 74 standard as the loading criteria for a broken wire condition. However, a transmission line designed on the basis of the RSL may be unsafe because the RSL takes no account of the dynamic impact effect. This study develops a general finite-element analysis procedure to resolve the conductor breakage problem and to determine the broken wire load (BWL) for the transmission-line design. The developed procedure can account for the impinging and friction effects between the broken conductor and the ground. A three-span transmission line with the line configurations previously tested at full-scale was examined, and the results showed that the developed procedure could predict a realistic time history of responses. The developed procedure was then applied to a nine-span transmission line, and the results showed that the peak BWL was significantly greater than the RSL, indicating that the peak BWL instead of the RSL should be used to check the extreme load case for the conductor's breakage condition. DOI: 10.1061/(ASCE)CF.1943-5509.0000133. (C) 2011 American Society of Civil Engineers.

关键词： Transmission line finite-element method Conductor breakage Longitudinal load Dynamic impact Broken wire load

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SEMIAUTOMATIC COMPUTER CONSTRUCTION OF 3-DIMENSIONAL SHAPES FOR THE finite-element method

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COMPUTER methodS AND PROGRAMS IN BIOMEDICINE 1993年第2期41卷 135-146页

作者： AHARON, S BERCOVIER, M HEBREW UNIV JERUSALEM INST COMP SCI JERUSALEM ISRAEL HEBREW UNIV JERUSALEM BERTOLD BADLER CHAIR COMP SCI JERUSALEM ISRAEL

Precise estimation of spatio-temporal distribution of ions (or other constitutives) in three-dimensional geometrical configuration plays a major role in biology. Since a direct experimental information regarding the free intracellular Ca2+ spatio-temporal distribution is not available to date, mathematical models have been developed. Most of the existing models are based on the classical numerical method of finite-difference (FD). Using this method one is limited when dealing with complicated geometry, general boundary conditions and variable or non-linear material properties. These difficulties are easily solved when the finite-element-method (FEM) is employed. The first step in the implementation of the FEM procedure is the mesh generation which is the single most tedious, time consuming task and vulnerable to mistake. In order to overcome these limitations we developed a new interface called AUTOMESH. This tool is used as a preprocessor program which generates two- and three-dimensional meshes for some known and often-used shapes in neurobiology. AUTOMESH creates an appropriate mesh by using the mesh generator commercial tool of FIDAP.

关键词： finite-element method FEM COMPUTER SIMULATION 3-DIMENSIONAL RECONSTRUCTION

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Calculation of effective diffusion coefficient in a colloidal crystal by the finite-element method

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RUSSIAN JOURNAL OF ELECTROCHEMISTRY 2012年第8期48卷 817-834页

作者： Volgin, V. M. Davydov, A. D. Kabanova, T. B. Tula State Univ Tula 300600 Russia Russian Acad Sci Frumkin Inst Phys Chem & Electrochem Moscow 119071 Russia

The work is devoted to the calculation of effective diffusion coefficient of ions from the bulk solution to the electrode through a mask and the calculation of the distribution of the limiting current density over the electrode surface. A colloidal crystal, which is formed by orderly arranged monodispersed spherical particles, serves as a mask. It is shown that the diffusion of electroactive ions in the pores between spherical particles can be simulated by unit cells with rhombic, rectangular, or triangular cross-section. In the latter case, the cell side surface has no periodical boundaries. This simplifies significantly the numerical solution of the Laplace's equation by the finite-element method. The effective diffusion coefficient in the bulk colloidal crystal is calculated at various values of its porosity. The calculated results agree well with the literature data. It is found that, for close-packed spherical particles, the relative effective diffusion coefficient in the bulk colloidal crystal is 0.16. The thicknesses of transient zones adjacent to the electrode surface and outer boundary of colloidal crystal and the effective diffusion coefficients for these zones are determined. The dependence of effective diffusion coefficient on the number of spherical particle layers in the colloidal crystal is obtained. The distribution of the limiting current density over the electrode surface is analyzed at various numbers of particle layers.

关键词： colloidal crystal effective diffusion coefficient limiting current distribution of current density numerical solution finite-element method

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THERMAL-ANALYSIS OF A DUAL-IN-LINE PACKAGE USING THE finite-element method

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IEE PROCEEDINGS-I COMMUNICATIONS SPEECH AND VISION 1987年第1期134卷 23-31页

作者： HARDISTY, H ABBOUD, J School of Mechanical Engineering University of Bath Bath UK

The thermal failure of electronic systems is becoming an increasingly difficult design problem, because of the trend to increase the packing density of components. This paper describes research in which the finite-element method (FEM) is used to investigate steady-state heat transfer in dual-in-line microelectronic package (DIP). Although the paper provides data for the specialist in package design, background information on heat transfer and the FEM has been included to demonstrate the broad applicability of the methods used. The stages in the development of finite-element models of first an 8-pin, and then a 16-pin, DIP are described. A systematic thermal analysis was carried out on the finite-element model of 16-pin DIP when cooled by air, first by natural and then by forced convection. The FEM revealed the complex 3-dimensional temperature field within the package. Computer runs over a range of power dissipation rates showed how both temperature distribution, and thermal resistance, changed in response to changes in external convection. As well as providing data for package cooling, the research highlights the difficulties inherent in providing a standard definition of thermal resistance for users.

关键词： natural air cooling forced convection thermal analysis 3-dimensional temperature field DIL type thermal resistance temperature distribution steady-state heat transfer finite-element method packaging Product packaging 8 pin type microelectronic package Packaging dual-in-line package thermal failure IC technology integrated circuit technology 16 pin type DIP Numerical analysis finite element analysis

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