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6th european Congress on Computational methods in Applied Sciences and engineering, ECCOMAS 2012

作者： Wang, W.D. Chang, L.Y. Xu, Z.H. Weng, Q.P. Department of Underground Structure and Geotechnical Engineering East China Architectural Design and Research Institute Co. LTD. 4F 220 Sichuan Road Shanghai 200002 China

ISBN: (纸本)9783950353709

the Shanghai 500kV World Expo Underground Transmission and Substation situated in the center district of Shanghai city. the project involved the construction of a four levels cylindrical underground structure with a diameter of 130 m. the excavation depth for the project was 34 m and it was constructed by top-down method in difficult soft soil condition. this paper presents the numerical analysis of the multi-propped deep excavation with undrained effective stress analysis method. Firstly, the geotechnical profile at the construction site and arrangement of the supporting system were introduced. Secondly, an axisymmetric finite element model was setup in the PLAXIS software package. the model included the diaphragm wall, the horizontal props, and the layered soils. the horizontal props were modeled by spring elements, the stiffness of which was obtained through three-dimensional finite element analysis of the horizontal props. the HS-small model was used to present the behavior of the Shanghai soft clays. At last, comparisons between the numerical prediction and the measured results were reported and discussed. It shows that the calculated lateral displacements of the diaphragm wall, the ground surface settlements, the circumferential axial forces in the wall, and the lateral pressure acting on the wall matched well with the measured results.

关键词： Finite element method

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Finite element simulation of dynamic pile penetration into a saturated porous medium

Finite element simulation of dynamic pile penetration into a...

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6th european Congress on Computational methods in Applied Sciences and engineering, ECCOMAS 2012

作者： Sabetamal, H. Nazem, M. Sloan, S.W. Carter, J.P. ARC Centre of Excellence for Geotechnical Science and Engineering University of Newcastle Newcastle NSW Australia

ISBN: (纸本)9783950353709

numerical modelling of dynamic penetration of objects into soil layers is one of the most challenging problems in computational geomechanics, mainly due to the extreme material nonlinearity, large deformations, and changing boundary conditions. numerical solution of such problems demands robust algorithms for time stepping as well as integration of the soil constitutive models. this paper presents the dynamic penetration of a pile into a nonlinear saturated porous medium, and addresses the pore water pressure distribution as well as the soil resistance mobilised during the installation phase. the finite element method, in conjunction with Biot's theory of consolidation, is used to model the coupled transient behaviour of the porous medium. the Arbitrary Lagrangian-Eulerian method is employed to avoid mesh distortion throughout the numerical simulation. the pile is treated as a rigid body and the interface between the soil and the pile is modelled using the so-called node-tosegment method of contact mechanics. the generalised-a method is employed to integrate the governing equations in the time domain. numerical results indicate that the proposed method is able to successfully solve these highly nonlinear problems of geomechanics in which either a saturated or unsaturated soil interacts with another structure.

关键词： Pore pressure

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Computational aspects for the accurate and efficient analysis of periodic planar leaky-wave antennas

Computational aspects for the accurate and efficient analysi...

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6th european conference on Antennas and Propagation, EuCAP 2012

作者： Valerio, G. Paulotto, S. Jackson, D.R. Wilton, D.R. Baccarelli, P. Galli, A. I.E.T.R. Institut D'Electronique et de Télécommunications de Rennes Université de Rennes 1 Rennes France Maxtena Antenna Innovation Company Bethesda MD United States Department of Electrical and Computer Engineering University of Houston Houston TX United States Department of Information Engineering Electronics and Telecommunications Sapienza University of Rome Rome Italy

ISBN: (纸本)9781457709180

Design techniques for leaky-wave antennas usually require complex analysis methods for the rigorous characterization of the radiating structures as a function of the various geometrical and physical parameters involved. An increasing number of such antenna topologies are based on planar stratified configurations with suitable inclusions of periodic metallic or dielectric perturbations. the prediction of the leaky-wave parameters (i.e., phase and leakage constants, etc.) is a difficult task to achieve in an accurate and efficient fashion. In this connection, the present contribution is focused on the computational aspects related to an integral-equation approach to the problem based on a mixed-potential formulation. By means of specific asymptotic extractions, powerful acceleration techniques for the relevant scalar and dyadic Green's functions are proposed and tested for different types and dimensions of periodicity. numerical results are provided and discussed for various significant types of periodic structures. © 2012 IEEE.

关键词： Periodic structures

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Static and dynamic analysis of journal bearing

Static and dynamic analysis of journal bearing

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6th european Congress on Computational methods in Applied Sciences and engineering, ECCOMAS 2012

作者： Shi, Dongyan Shi, Xianjie Han, Jiashan College of Mechanical and Electrical Engineering Harbin Engineering University Harbin 150001 China

ISBN: (纸本)9783950353709

In this paper, a numerical method is presented to predict the static and dynamic characteristic of journal bearing taking the bearing load direction and oil groove into consideration. Based on numerical difference method, oil film pressure distribution on journal bearing is obtained with point-by-point relaxation iteration method. then, the dynamic characters are calculated by numerical integral algorithm. Finally, the calculation program of dynamic characteristics of journal bearing is developed. the computation method provides a useful guide for the numerical simulation of rotary machines.

关键词： Journal bearings

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numerical flow simulations used in industrial problems

Numerical flow simulations used in industrial problems

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6th european Congress on Computational methods in Applied Sciences and engineering, ECCOMAS 2012

作者： Adámek, Karel Kolář, Jan VÚTS Liberec A.s. U Jezu 525/4 CZ-46119 Liberec Czech Republic

ISBN: (纸本)9783950353709

the paper presents and describes some results of numerical flow simulations, used for description or solution of various industrial problems. Sometimes, it seems that the substance of the problem should be found in the area of the flow mechanics, but after some discussion of results of numerical flow simulations it is clear that the substance of the problem could be another - either pure mechanical or else.

关键词： Textile finishing

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Effects of numerical models on internalblasting simulation of a tube-tunnel

Effects of numerical models on internalblasting simulation o...

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6th european Congress on Computational methods in Applied Sciences and engineering, ECCOMAS 2012

作者： Wang, Zhengbo Yuan, Y. Department of Geotechnical Engineering TongJi University 1239 Siping Road Shanghai 200092 China

ISBN: (纸本)9783950353709

Simulating behavior of a tunnel subjected to internal blasting should consider related soil, structural concrete, air, and explosive. 3D finite element model is built in this paper, and explicit dynamical analysis software LS-DYNA is applied. Air and explosive form the multi-material fluid with equation of state (EOS) to describe blast load. Penalty coupling method is used to simulate fluid-structure coupling, in which tunnel structure is meshed as Lagrange element and multi-material fluid is meshed as arbitrary Lagrange-Euler (ALE) element. Tunnel models with different burial depth, explosive charge and explosion sites are considered. Soil-structure constraint condition is of great importance in the simulation, and the necessity to set contact between soil and structure is verified, which illustrates that perfect bonding method is improper. the results of contact parameter sensitivity analysis(PSA) show that friction coefficient and decay parameters DC and VDC are essential but not sensible in contact setting. the soil-structure contact pressure remained after internal explosion is in direct proportion to soil shear stiffness, which affects the dynamic response of tunnel.

关键词： Dynamic response

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Multiscale numerical modeling of composite material: A combined FE-ANN approach

Multiscale numerical modeling of composite material: A combi...

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6th european Congress on Computational methods in Applied Sciences and engineering, ECCOMAS 2012

作者： Boso, Daniela P. Lefik, Marek Schrefler, Bernhard A. Dipartimento di Ingegneria Civile Edile Ed Ambientale Università di Padova Via Francesco Marzolo 9 35131 Padova Italy Department of Geotechnical Engineering and Engineering Structures Technical University of Lódz Al.Politechniki 6 93-590 Lódz Poland

ISBN: (纸本)9783950353709

In this paper we present a combined finite element (FE) - artificial neural network (ANN) approach for the analysis of the behavior of non linear composites and hierarchical structures. Different aspects of ANN use in multiscale numerical homogenization are shown. First, the possibility to model via ANNs the effective material starting from a relatively small set of suitable virtual or real experiments performed on a unit cell is discussed. ANN based procedures can also be exploited in a multiscale analysis as a tool for the stress-strain recovery at lower levels of a hierarchical structure. In many situations a map of the strain and stress state at the lowest level is needed. To this aim, it is necessary to calculate the strain state in the most strained point for each material of the repetitive cell. In other cases, it is of interest to know if and when at least one of the non linear composite material is e.g. yielding, checking all the gauss points of all the elements. these two post-processing procedures, together with the unsmearing itself, are numerically very costly. An ANN, acting in recall mode during the execution of the homogenization loops, allows for a considerably improved computational efficiency. Finally, a significant application for the design of composites is shown. ANN can be used for the identification of the effective material coefficients of a system characterized by a cell of periodicity with a variable geometry.

关键词： Neural networks

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numerical homogenization of transfer properties of heterogeneous media by immersed interface method

Numerical homogenization of transfer properties of heterogen...

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6th european Congress on Computational methods in Applied Sciences and engineering, ECCOMAS 2012

作者： Do, Duc-Phi Hoxha, Dashnor Wu, Senjun Belayachi, Naima Polytech Orleans 8 rue Léonard de Vinci 45072 Orleans cedex 2 France

ISBN: (纸本)9783950353709

the purpose of the present work is to determine the effective transfer properties of heterogeneous media by using a numerical approach based on the Immersed Interface Method (IIM). For that, an extension of this numerical method is carried out in the framework of non linear behavior of medium containing inner boundary in form of perfect or imperfect interfaces between constituents. the evolution of the homogenized properties with respect to the properties of individual component, the volume fraction and size of inclusion is highlighted. the performance of developed tool is then proved through the studies of the temperature dependence of effective conductivity of heterogeneous media.

关键词： numerical methods

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Preliminary evaluation of the seismic response of the ELSY LFR

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NUCLEAR engineering AND DESIGN 2012年 242卷 361-368页

作者： Lo Frano, R. Forasassi, G. Univ Pisa Dept Mech Nucl & Prod Engn I-56126 Pisa Italy

the main goal of the present study is the preliminary evaluation of the seismic demand of a LFR with reference to european Lead System project (ELSY) considered one of the most promising innovative Generation IV reactor. the safety aspects of the ELSY reactor in the event of a Safe Shutdown Earthquake, taking into account also the effects of the possible fluid-structure interaction, have been analyzed. To the purpose to determine the seismic demand, in according with the international rules, a non-linear dynamic analysis method was used with rather refined 3-D model of LFR for the foreseen structural analyses and simulations of the plant and of the reactor internals behaviour. In this report numerical results are presented and discussed highlighting the relevance of the fluid-structure interaction in terms of structural integrity as well as the isolation technique effectiveness, which is expected to increase the safety margin of the reactor structures during a seismic event, if the isolators frequency is far from that of the reactor. the present work has been performed within the 6th european Framework Project. (C) 2011 Elsevier B.V. All rights reserved.

关键词： SEISMIC response (Structural analysis) NUCLEAR reactors -- Safety measures FLUID-structure interaction SIMULATION methods & models NONLINEAR mechanics MAthEMATICAL models

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Dual-tree complex wavelet transform based denoising for random spray image enahcement methods

Dual-tree complex wavelet transform based denoising for rand...

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6th european conference on Colour in Graphics, Imaging, and Vision 2012, CGIV 2012

作者： Fierro, Massimo Kyung, Wang-Jun Ha, Yeong-Ho School of Electrical Engineering and Computer Science Kyungpook National University Taegu Korea Republic of

ISBN: (纸本)9781622767014

this work introduces a novel way to reduce point-wise noise introduced or exacerbated by image enhancement methods leveraging the Random Spray sampling approach. Due to the nature of the spray, the sampling structure used, output images for such methods tend to exhibit noise with unknown distribution. the proposed noise reduction method is based on the assumption that the non-enhanced image is either free of noise or contaminated by non-perceivable levels of noise. the dual-tree complex wavelet transform is applied to the luma channel of both the non-enhanced and enhanced image. the standard deviation of the energy for the non-ehanced image across the six orientations is computed and normalized. the normalized map obtained is used to shrink the real coefficients of the enhanced image decomposition. A noise reduced version of the enhanced version can then be computed via the inverse transform. A thorough numerical analysis of the results has been performed in order to confirm the validity of the proposed approach.

关键词： Image enhancement

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