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第十二届国际混凝土碱集料反应会议

作者： Rogério Carrazedo Luiz Alkimin de Lacerda Department of Civil Engineering Graduate Program in Numerical Methods in Engineering Federal University of Parana Curitiba Brazil.LACTEC-Institute of Technology for Development Curitiba Brazil Department of Civil Engineering Graduate Program in Numerical Methods in Engineering Federal University of Paraná Curitiba Brazil. LACTEC-Institute of Technology for Development Curitiba Brazil

Concrete strength and durability reduction are two of the major consequences of the long-term chemical reaction evolution between the cement alkali and certain minerals from the aggregate. This reaction is known as alkali-aggregate reaction. It provokes a heterogeneous expansion of the concrete causing geometry changes and eventually, loss of functionality. In concrete dams these effects can be very costly and the development of numerical tools to diagnose and correct the problem should be welcome. In this work, a parametric model to simulate concrete expansion is proposed, which uses the main AAR influence factors to form its basis. The employed methodology consists on obtaining the spatial distribution of these influence factors, parameters normalization and the use of a constitutive relationship to retrieve the expansive AAR rate of deformation. An optimization technique is also employed to adjust the computed parameters to existing field measurements. The methodology was developed in a commercial finite element package and tested in a for simple three-dimensional finite element model.

关键词： Alkali-aggregate reaction, finite element method, parametric model, influence factors.

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Empirical investigation of the effect of the door's state on received signal strength in indoor environments at 2.4 GHz

Empirical investigation of the effect of the door's state on...

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IEEE Conference on ALocal Computer Networks Workshops (LCN Workshops)

作者： Alaa Alhamoud Michael Kreger Haitham Afifi Christian Gottron Daniel Burgstahler Frank Englert Doreen Böhnstedt Ralf Steinmetz Multimedia Communications Lab Technische Universität Darmstadt Darmstadt Germany Institute of Numerical Methods and Informatics in Civil Engineering Technische Universität Darmstadt Darmstadt Germany Information of Engineering and Technology German University in Cairo Cairo Egypt

ISBN: (纸本)9781479937851

Due to the wide deployment of indoor wireless local area networks (WLANs), the indoor planning became a research of interest for IT as well as networking researchers. As a result of this wide deployment, many IT applications and services started relying on the ready implemented WLAN infrastructure. Therefore, there is a need for reliable propagation models which are able to predict the WLAN signal strength in indoor environments before starting the real world deployment which leads to an efficient and cost aware deployment process. In this paper we develop an empirical propagation model which focuses mainly on the effect of the door state on the propagated WLAN signal in indoor environments. The measurements were compared to other simulated results in literature. A new empirical parameter based on empirical measurements was introduced for a better estimation of the received signal strength (RSS).

关键词： Computational modeling Indoor environments Mathematical model Receivers Propagation losses Predictive models Transmitters

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An Educational GUI-Based Software for Dynamic Analysis of Framed Structural Models

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Journal of Software engineering and Applications 2023年第7期16卷 265-286页

作者： Claudio H. B. Resende Pedro C. Lopes Rafael L. Rangel Luis F. Paullo Muñoz Luiz F. Martha Department of Civil and Environmental Engineering Pontifical Catholic University of Rio de Janeiro Rio de Janeiro Brazil Institute of Computing Fluminense Federal University Niter&#243i Brazil International Centre for Numerical Methods in Engineering (CIMNE) Universitat Politècnica de Catalunya Barcelona Spain

This paper introduces a new version of the open-source educational software, LESM (Linear Elements Structure Model), developed in MATLAB for structural analysis of one-dimensional models such as frames, trusses, and grillages. The updated program includes dynamic analysis, which incorporates inertial and damping effects, time-dependent load conditions, and a transient solver with multiple time integration schemes. The software assumes small displacements and linear-elastic material behavior. The paper briefly explains the theoretical basis for these developments and the reorganization of the source code using Object-Oriented Programming (OOP). The updated Graphical User Interface (GUI) allows interactive use of dynamic analysis features and displays new results such as animations, envelope diagrams of internal forces, phase portraits, and the response of degrees-of-freedom in time and frequency domain. The new version was used in a structural dynamics course, and new assignments were elaborated to improve students’ understanding of the subject.

关键词： Structural Analysis Structural Dynamics Educational Software MATLAB Graphical User Interface

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Very High Order Finite Volume Solver for Multi Component Two-Phase Flow with Phase Change Using a Posteriori Multi Optimal Order Detection

SSRN

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SSRN 2024年

作者： Deligant, Michael Romero Casado, Carlos Nogeira, Xesus Ramirez, Luis Specklin, Mathieu Bakir, Farid Khelladi, Sofiane PIMM Arts et Métiers Institute of Technology CNAM LIFSE HESAM University ParisF-75013 France Group of Numerical Methods in Engineering-GMNI Center for Technological Innovation in Construction and Civil Engineering-CITEEC Universidade da Coruña Civil Engineering School Campus de Elviña A Coruña15071 Spain

This paper presents a very high order compressible multicomponent two-phase flow solver with phase transition. It is based on finite volume approach using moving least square reproducing kernels for high order reconstructions. It is also coupled with multi optimal order detection (MOOD) to get high accuracy low dissipation scheme while maintaining boundedness and preventing numerical oscillations at interfaces and strong gradient zones. The properties of the proposed framework are demonstrated on classical test problems starting with convergence order verification on simple scalar advection test cases. More complex shock and more stringent tubes tests with various water, steam and air concentration are then simulated and compared with available reference in the literature. Finally the ability of the proposed approach is illustrated with the simulation of a liquid oxygen jet in gaseous hydrogen. The results features vortices, mixing and evaporation at the liquid/vapor interface. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

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Shooting-projection method for a small object moving under the influence of a force 10

Shooting-projection method for a small object moving under t...

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202 10th International Conference on engineering Mathematics and Physics, ICEMP 2021

作者： Filipov, S.M. Faragó, I. Avdzhieva, A. Department of Computer Science Faculty of Chemical and System Engineering University of Chemical Technology and Metallurgy 8 St. Kliment Ohridski Blvd. Sofia1756 Bulgaria Department of Differential Equations Institute of Mathematics Budapest University of Technology and Economics MTA-ELTE Research Group Egry József u. 1 Budapest1111 Hungary Department of Numerical Methods Faculty of Mathematics and Informatics Sofia University St. Kliment Ohridski 5 James Bourchier Blvd. Sofia1164 Bulgaria

We consider a small object in 3D moving under the influence of a force that may depend explicitly on time, on the position of the object, and on its velocity. The equations of motion of classical mechanics are assumed to hold. If the position of the object is specified at some initial and some final time, obtaining the trajectory of the object requires the solution of a two-point boundary value problem. To solve the problem various numerical technics can be applied. This paper extends the recently proposed shooting-projection method to 3D. We introduce a Lagrangian from which, applying the principle of least action, the projection trajectory is derived. Analysis of the action reveals the meaning of the projection trajectory. Using the shooting-projection method, the considered two-point boundary value problem is solved for the case of a projectile motion in the presence of air resistance and wind. © 2021 institute of Physics Publishing. All rights reserved.

关键词： Trajectories

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Finite element analysis of the superplastic forming of thick sheet using the incremental flow formulation

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International Journal for numerical methods in engineering 1998年第17期40卷

作者： J. Bonet P. Bhargava R. D. Wood Institute for Numerical Methods in Engineering Department of Civil Engineering University of Wales Swansea SA2 8PP U.K.

The paper discusses the finite element analysis of the superplastic forming of thick sheet components. The incremental formulation proposed is based on a geometrical approximation of the flow type of constitutive equations that describe the behaviour of the alloy during forming. The spatial discretization is achieved using eight-noded finite elements. An algorithm capable of predicting the correct forming pressure is also presented in a form consistent with the incremental flow formulation. Some experimental validation of these techniques will be shown together with a number of more realistic applications which will illustrate the generality of these techniques and their ability to simulate the forming of complex components. Most of the material in this section is standard but has been included for the purpose of completeness and to introduce the reader to the notation used in the paper. © 1997 John Wiley & Sons, Ltd.

关键词： finite elements superplasticity incremental flow formulation thick sheet forming average deformation gradient element

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Correction to: Understanding the carbonation of concrete with supplementary cementitious materials: a critical review by RILEM TC 281-CCC

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Materials and Structures 2020年第1期54卷 1-2页

作者： von Greve-Dierfeld, Stefanie Lothenbach, Barbara Vollpracht, Anya Wu, Bei Huet, Bruno Andrade, Carmen Medina, César Thiel, Charlotte Gruyaert, Elke Vanoutrive, Hanne Saéz del Bosque, Isabel F. Ignjatovic, Ivan Elsen, Jan Provis, John L. Scrivener, Karen Thienel, Karl-Christian Sideris, Kosmas Zajac, Maciej Alderete, Natalia Cizer, Özlem Van den Heede, Philip Hooton, Robert Douglas Kamali-Bernard, Siham Bernal, Susan A. Zhao, Zengfeng Shi, Zhenguo De Belie, Nele TFB Technology and Research for Concrete Structures Wildegg Switzerland Swiss Federal Laboratories for Materials Science and Technology (Empa) Laboratory for Concrete and Construction Chemistry Dübendorf Switzerland Faculty of Civil Engineering Institute of Building Materials Research RWTH Aachen University Aachen Germany Microlab Faculty of Civil Engineering and Geosciences Delft University of Technology Delft The Netherlands LafargeHolcim Innovation Center Saint-Quentin-Fallavier Cedex France International Centre for Numerical Methods in Engineering (CIMNE) Barcelona Spain Department of Construction Institute for Sustainable Regional Development (INTERRA) University of Extremadura Cáceres Spain Technical University of Munich Center for Building Materials Munich Germany Department of Civil Engineering Structural Mechanics and Building Materials KU Leuven Ghent Belgium Department of Materials and Structures Faculty of Civil Engineering Institute of Materials and structures University of Belgrade Belgrade Serbia Department of Earth and Environmental Sciences KU Leuven Louvain Belgium Department of Materials Science and Engineering University of Sheffield Sheffield UK Construction Materials Laboratory École polytechnique fédérale de Lausanne Lausanne Switzerland Department of Civil Engineering and Environmental Sciences University of the Bundeswehr Munich Neubiberg Germany Department of Civil Engineering Democritus University of Thrace Xanthi Greece Global R&D HeidelbergCement AG Leimen Germany Department of Structural Engineering and Building Materials Ghent University Ghent Belgium Departement of Civil Engineering KU Leuven Louvain Belgium Department of Civil and Mineral Engineering University of Toronto Toronto Canada National Institute of Applied Sciences of Rennes Rennes France School of Civil Engineering University of Leeds Leeds UK Building Materials Urban and Environment Research University of Liège Liège Belgium

Dr. Isabel Martins was missing from the RILEM membership list that was published in the original article. The original article has been corrected.

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Correction to: Understanding the carbonation of concrete with supplementary cementitious materials: a critical review by RILEM TC 281-CCC

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Materials and Structures 2021年第2期54卷 1-2页

作者： von Greve-Dierfeld, Stefanie Lothenbach, Barbara Vollpracht, Anya Wu, Bei Huet, Bruno Andrade, Carmen Medina, César Thiel, Charlotte Gruyaert, Elke Vanoutrive, Hanne del Bosque, Isabel F. Saéz Ignjatovic, Ivan Elsen, Jan Provis, John L. Scrivener, Karen Thienel, Karl-Christian Sideris, Kosmas Zajac, Maciej Alderete, Natalia Cizer, Özlem Van den Heede, Philip Hooton, Robert Douglas Kamali-Bernard, Siham Bernal, Susan A. Zhao, Zengfeng Shi, Zhenguo De Belie, Nele TFB Technology and Research for Concrete Structures Wildegg Switzerland Swiss Federal Laboratories for Materials Science and Technology (Empa) Laboratory for Concrete and Construction Chemistry Dübendorf Switzerland Faculty of Civil Engineering Institute of Building Materials Research RWTH Aachen University Aachen Germany Microlab Faculty of Civil Engineering and Geosciences Delft University of Technology Delft The Netherlands LafargeHolcim Innovation Center Saint-Quentin-Fallavier Cedex France International Centre for Numerical Methods in Engineering (CIMNE) Barcelona Spain Department of Construction Institute for Sustainable Regional Development (INTERRA) University of Extremadura Cáceres Spain Center for Building Materials Technical University of Munich Munich Germany Department of Civil Engineering Structural Mechanics and Building Materials KU Leuven Ghent Belgium Department of Materials and Structures Faculty of Civil Engineering Institute of Materials and Structures University of Belgrade Belgrade Serbia Department of Earth and Environmental Sciences KU Leuven Louvain Belgium Department of Materials Science and Engineering University of Sheffield Sheffield UK Construction Materials Laboratory École polytechnique fédérale de Lausanne Lausanne Switzerland Department of Civil Engineering and Environmental Sciences University of the Bundeswehr Munich Neubiberg Germany Department of Civil Engineering Democritus University of Thrace Xanthi Greece Global R&D HeidelbergCement AG Leimen Germany Department of Structural Engineering and Building Materials Ghent University Ghent Belgium Departement of Civil Engineering KU Leuven Louvain Belgium Department of Civil and Mineral Engineering University of Toronto Toronto Canada National Institute of Applied Sciences of Rennes Rennes France School of Civil Engineering University of Leeds Leeds UK Building Materials Urban and Environment Research University of Liège Liège Belgium

A correction to this paper has been published: https://***/10.1617/s11527-020-01558-w

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Finite element analysis of solidification using object-oriented and parallel techniques

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International Journal for numerical methods in engineering 1998年第15期40卷

作者： I. Masters A. S. Usmani J. T. Cross R. W. Lewis Institute for Numerical Methods in Engineering University of Wales Swansea Singleton Park Swansea SA2 8PP U.K. Department of Civil Engineering University of Edinburgh Edinburgh U.K.

This paper describes an implementation in C++ and in parallel of an explicit finite element formulation for the solution of transient heat conduction problems with phase change. The scheme requires a very small timestep because of its conditional stability, but, as no matrix inversion is required, the cost per timestep is an order of magnitude lower than for a conventional scheme. The principles of using object-oriented techniques for general finite element programming are briefly explained, while the advantages for parallel processing are described in detail, including the classes used to perform message passing. An example is given showing the performance of the scheme on two completely different parallel machines: a shared memory Silicon Graphics Power Challenge, and a distributed memory Cray T3D. The results indicate that the program scales efficiently for large meshes. © 1997 John Wiley & Sons, Ltd.

关键词： C++ object-oriented solidification parallel

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Aspects of shape an parameter sensitivity analysis in the theory of porous media

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PAMM 2008年第1期7卷

作者： Franz-Joseph Barthold Jörg Stieghan Department of Civil Engineering Chair of Numerical Methods and Information Processing Technical University of Dortmund D-44227 Dortmund Germany Department of Mechanical Engineering Institute for Particle Technology Technical University of Braunschweig D-38104 Braunschweig Germany

This contribution is concerned with the application of variational shape sensitivity analysis and parameter sensitivity analysis to the theory of porous media. Both areas contribute to structural optimization and other inverse problems like parameter identification. The correct and efficient derivation, implementation and computation of the sensitivities, that are the gradient values of objectives and constraints with respect to different kind of design variables, have a significant influence on the overall performance of the nonlinear programming algorithms applied to the numerical treatment of inverse problems. The theory of porous media is built upon the mixture of several phases and their interaction using the concept of volume fractions. Thus, a complex continuum mechanical description for each single phase as well as for the whole mixture is used in this approach. This proposal formulates a general viewpoint using an intrinsic formulation in local coordinates which permit a rigorous split of continuum mechanical functions into parts being either geometry or deformation depending. The variational approach to sensitivity analysis is built not only upon this separation but also upon material parameters and yields some general insight into the structure of porous media. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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