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7th European Conference on e-Learning

作者： Daniunas, Valentas Gontis, Vygintas Acus, Arturas Fokas, Vytautas Vallauga, Gintaras Vilnius Univ Inst Theoret Phys & Astron Vilnius Lithuania

ISBN: (纸本)9781906638221

For the distance learning and scientific cooperation the possibility to run software by Internet is essential. WebMathematica represents technically the most complex part of the website mokslasplius. It (***), where a number of sophisticated interactive experiments from diverse areas of physics is realized. Enhanced by specially designed php-webMathematica module, it enables the realization of step-by-step training style pages where many of the intermediate steps can be evaluated and stored with the intention for later reuse in the process of presentation. AnyLogic software package allows one to develop interactive models of various physical systems of different nature: continuous, discrete or hybrid, and publish these models as java applets directly into Internet. We do present examples of web based interactive models collected under the title 'Physics of Risk" - the new field of the applications of physics in social sciences and complexity. The article also analyses integration of various software packages, as open source content management system Drupal, server-side software (Tomcat server, webMatematica), java applets, specialized computer modelling tools for purposes of e-Learning, science popularisation and dissemination of educational information, paying particular attention to the easiness of access to the content of portal, its usability for practical educational processes, and visual appeal.

关键词： e-Learning computer modelling and simulation educational web environment

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Influence of yttrium on the interface valence electron density of thermal barrier coatings

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MATERIALS CHEMISTRY AND PHYSICS 2007年第2-3期105卷 278-285页

作者： Li, Zhilin Liu, Wei Wu, Yuanqi Beijing Univ Chem Technol Coll Mat Sci & Engn Beijing 100029 Peoples R China Beijing Univ Chem Technol Coll Chem Engn Beijing 100029 Peoples R China

Most of the bonding layers of thermal barrier coatings contain some yttrium to improve the physical consistency of the substrate and the ceramics layer. But the reason of the improvement and the proper yttrium content are not clear. In this paper, the valence electron densities P-hk1 and P-uvw of the two sides and their difference Delta p(min) of the bonding layer/ceramic layer interface of thermal barrier coatings are calculated with the empirical electron theory in solids and molecules at various bonding layer yttrium content. The results show the following. The addition of yttrium has beneficial effect on the decrease of the interface stress because it decreases the The addition of yttrium can also increase the valence electron density P-hk1 or p(uvw) of the interface and so increase the interface cohesion force. The most effective yttrium content is at 0.4 wt% or so. The deductions accord with the actual coating, so the method can be applied to design the composition of the bonding layer of thermal barrier coatings. Furthermore. the calculation and the analysis methods of the interface valence electron densities can also be extended to other crystal coatings or composites with special orientation relationship, no matter the interface is a alloy/alloy one, a ceramics/alloy one or a ceramics/ceramics one. (c) 2007 Elsevier B.V. All fights reserved.

关键词： alloys coatings interfaces computer modelling and simulation

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Effect of backbone on the biaxial retardation of polyimide films in uniaxial stretch

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MATERIALS CHEMISTRY AND PHYSICS 2007年第1期103卷 35-40页

作者： King, Jinn-Shing Whang, Wha-Tzong Lee, Wen-Chin Chang, Li-Ming Natl Chiao Tung Univ Dept Mat Sci & Engn Hsinchu 300 Taiwan Ind Technol Res Inst Mat & Chem Res Labs Hsinchu 310 Taiwan

A biaxial-retardation film prepared from the uniaxial-stretched polyimide (PI) film was developed for compensating the viewing angle of liquid-crystal displays. Good uniformity of in-plane bireffingence in well-stretched PI films was observed visually with two crossed polarizers. The prism coupling method was used to measure the n(x), n(y), n(z), and thickness of the stretched PI films. The birefringence variations of n, - n, (difference of refractive indices between x- and y-axes) and n(x) - n(z) during the stretching process were highly affected by PI structure. The polarizability tensors and intrinsic birefringences of the PI repeat units were estimated by Gaussian 98W. It was found that the stretch-induced birefringence is more related to the average polarizability per volume at the low elongation period. (C) 2006 Elsevier B.V. All rights reserved.

关键词： optical materials polyimide computer modelling and simulation birefringence

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Neural computation to correlate HVOF thermal spraying parameters with the magnetic properties of FeNb alloy deposits

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MATERIALS CHEMISTRY AND PHYSICS 2005年第1期93卷 181-186页

作者： Cherigui, M Guessasma, S Fenineche, N Coddet, C UTBM LERMPS F-90010 Belfort France

The effect of the HVOF process parameters on coating porosity and magnetic properties of FeNb deposits was studied using artificial neural network methodology. A first artificial neural network was used and optimized to relate process parameters to the magnetic properties of the coating. The effect of process parameters on magnetic properties was quantified by a second network. Predicted magnetic properties correlated with coating porosity were obtained using these optimized network structures. It was then possible to identify the role of porosity with regards to improvement of coercivity and saturation magnetization. (c) 2005 Elsevier B.V. All rights reserved.

关键词： amorphous materials coatings magnetic properties computer modelling and simulation

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Ordering of fluoro-smectogen in a dielectric medium - a computational approach

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MATERIALS CHEMISTRY AND PHYSICS 2005年第1期90卷 159-165页

作者： Ojha, DP Pisipati, VGKM Nagarjuna Univ Fac Phys Sci Ctr Liquid Crystal Res & Educ Nagarjuna Nagar 522510 Andhra Pradesh India

A computational analysis of ordering in fluoro-smectogen, 4-propoyloxyphenyl 4-(4-trifluoromethylbenzoyloxy) benzoate (FLUORO), has been carried out with respect to translatory and orientational motions. The complete neglect differential overlap (CNDO/2) method has been employed to compute the net atomic charge and atomic dipole moment at each atomic centre. The modified Rayleigh-Schrodinger perturbation theory with the multi-centered-multipole expansion method has been employed to evaluate long-range intermolecular interactions, while a '6-exp' potential function has been assumed for short-range interactions. The interaction energy values obtained through these computations were used to calculate the probability of each configuration in a dielectric medium (i.e., non-interacting and non-mesogenic solvent, benzene) at room temperature (300 K), transition temperature (488 K) and above transition temperature (550 K). The flexibility of various configurations has been studied in terms of the variation of probability due to small departures from the most probable configuration. An attempt has been made to develop a new and interesting model of smectogen in a dielectric medium. The present investigation provides theoretical support to the experimental observations. (C) 2004 Elsevier B.V. All rights reserved.

关键词： liquid crystals computer modelling and simulation fluoro-smectogen

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Embryonic forms of nickel: a molecular-dynamics computer simulation

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JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM 2005年第1-3期716卷 165-174页

作者： El-Bayyari, Z Philadelphia Univ Fac Sci Dept Basic Sci Aein Albasha 19392 Jordan

An empirical many body potential energy function (PEF), incorporating two- plus three-body atomistic potential derived by fitting experimental data pertaining to bulk nickel, has been applied to study the structural stability and energetics of nickel microclusters containing 3-13 atoms, a growth towards the first fcc shell. A constant temperature molecular-dynamics (MD) technique is employed in the simulation. It is found that the energetically most stable structures of nickel microclusters are in three-dimensional distorted compact forms close to symmetric geometries. The theoretical predictions are compared to the available theoretical and experimental literature data for binding energies, bond lengths, and the most stable microcluster geometry. (c) 2004 Elsevier B.V. All rights reserved.

关键词： molecular-dynamics nanostructures computer modelling and simulation nickel clusters

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Studies of magnetic properties of iron-based coatings produced by a high-velocity oxy-fuel process

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MATERIALS CHEMISTRY AND PHYSICS 2005年第2-3期92卷 419-423页

作者： Cherigui, M Guessasma, S Fenineche, N Hamzaoui, R El-Kedim, O Coddet, C UTBM LERMPS F-90010 Belfort France UTBM CNRS UMR 5060 Nanomat Res Grp F-90010 Belfort France

The paper studies the effect of high-velocity oxy-fuel thermal spraying parameters, in particular spray distance and oxygen flow rate, on coating porosity and magnetic properties of FeSi and FeSiB deposits using the artificial neural network methodology. The magnetic properties correlated to coating porosity were obtained using an optimized network structure. The predicted results permitted to point out the role of porosity for varying the coercivity and saturation magnetization and the stability of magnetic properties with respect to the considered spray parameters. © 2005 Elsevier B.V. All rights reserved.

关键词： magnetic materials coatings computer modelling and simulation magnetic properties

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modelling nonlinear systems by scale considerations

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MATHEMATICAL AND computer modelling 2004年第7-8期40卷 797-807页

作者： Pantelis, G Intercoll Dept Comp Sci CY-6500 Larnax Cyprus

The macroscopic scale equations which generate locally averaged or filtered variables for nonlinear applications are examined. Conditions of consistency are derived that describe how well the filtered variables satisfy the exact macroscopic scale equations given any model for the residual. An approximate model for the residual is constructed for general nonlinear systems. The theory is demonstrated for the Euler equations for compressible fluid flow and an assessment of the residual model based on global energy balance is made by a numerical experiment. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： nonlinear models partial differential equations computer modelling and simulation large-eddy simulation

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Relaxation of granular gas under gravity

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PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS 2003年第SUPP期323卷 155-170页

作者： Loguinova, NB van Heijst, GJF Schram, PPJM Trigger, SA Vlasov, YP Eindhoven Univ Technol NL-5600 MB Eindhoven Netherlands Moscow State Univ Transport Commun Moscow 101475 Russia Joint Inst High Temp RAS Moscow 127412 Russia

The granular gas dynamics under gravity is investigated by means of numerical simulation for the case of elastic collisions. Damped oscillations in the process of evolution to equilibrium are found and considered in detail. The nature of the oscillations is the deviation of the position of the centre-of-mass of the system from the equilibrium one when the particles' initial velocity distribution is isotropic. The influence of several parameters on the oscillation frequency and the damping rate are determined. (C) 2003 Elsevier Science B.V. All rights reserved.

关键词： granular systems granular models of complex systems computer modelling and simulation mechanics of discrete systems ED-algorithm HS simulation relaxation processes gravity

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Segregation and ordering at alloys surfaces: modelling and experiment confronted

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APPLIED SURFACE SCIENCE 2003年第1-2期219卷 11-27页

作者： Creemers, C Deurinck, P Helfensteyn, S Luyten, J Katholieke Univ Leuven Fys Chem Lab B-3001 Louvain Belgium

Model calculations combining the Monte Carlo (MC) method and a suitable energy model are proposed as fully complementary to experiments in order to gain insight in segregation and other surface phenomena, deployed by materials in order to minimise their surface free energy and hence their total Gibbs free energy. In the confrontation between experiments and modelling. it is basically assumed that the surface, as observed in the experiments, corresponds to the equilibrium situation of minimal Gibbs free energy. The entropy part is modelled by the stochastic nature of Monte Carlo simulations, while the energy part is taken into account by the (modified) embedded atom method ((M)EAM). Special attention is paid to the derivation of model parameters that are specific for the alloy under study. For it appears that in several cases the experimental data can only correctly be reproduced with these specific EAM parameters. This article further focuses on the determination of the degree of order in the bulk. simulations according to the Grand Canonical Ensemble require the difference in chemical potential between the components. A novel approach is presented for deriving this parameter both for slightly off-stoichiometric ordered alloys and for disordered alloys. Results of MC/(M)EAM simulations are presented for the surfaces of five catalytically important binary alloys: Au75Pd25(1 10), Cu75Pd25(1 1 0), Pt50Ni50(l 0 0), 0 10) and (I 1 1), Pt80Fe20(l 1 1) and Pt75Sn25(l 1 1). It can be concluded that these simulations yield excellent predictions for surface modifications and are a very powerful tool to model and understand surfaces at equilibrium. (C) 2003 Elsevier Science B.V. All rights reserved.

关键词： surface segregation surface thermodynamics computer modelling and simulation single crystal surfaces copper gold iron nickel palladium platinum tin

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