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modelling of an underground waste disposal site by upscaling and simulation with domain decomposition method

Lecture Notes in Computational Science and Engineering 2005年 40卷 521-528页

作者： Boursier, I. Bourgeat, A. Tromeur-Dervout, D. Modelling and Scientific Computing Laboratory University Lyon 1 France

ISBN: (纸本)3540225234

We derive an upscaled but accurate 2D model of the global behavior of an underground radioactive waste disposal. This kind of computation occurs in safety assessment process. Asymptotic development of the solution leads to solve terms of order 1 on more regular and steady-state auxiliary problems. Neumann-Dirichlet domain decomposition methods, with non matching spectral grids, are performed to solve those auxiliary problems. Fourier and Chebychev polynomials approximation of the solution are used depending on boundary conditions implemented on subdomains. Since spectral representation of the solution or its derivatives allows accurate mappings between the interfaces of the different grids, we speed up the convergence of the Neumann-Dirichlet method by the Aitken acceleration which is sensitive to the accuracy of the representation of the iterate solution on the artificial interfaces. In order to enforce regularity for the spectral approximation, some regular extensions and filtering techniques on the artificial interfaces for the right hand side of the problem and the iterate solution are implemented.

关键词： Domain decomposition methods

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On some probability results characterizing the distribution in micro-economic structures using the formula of Faà di Bruno 1

On some probability results characterizing the distribution ...

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1st International Conference of Computer Science and Renewable Energies, ICCSRE 2018

作者： Chaachoui, Ghizlane El Khomssi, Mohammed Modelling and Scientific Computing Laboratory Faculty of Science and Technology of Fez Box 2202 University S. M. Ben Abdellah Fez Morocco

ISBN: (纸本)9789897584312

In this article we will treat the distribution of individuals in micro-economic structures in two different cases. In the first one, no constraints on the types are imposed on individuals or structures, in the second one, three types of constraints are imposed. This work is finished by an application that combines between two techniques, one purely theoretical based on the formula of Faà Di Bruno and the other is very practical having an economic aspect, in order to help and to facilitate the management of the distributions of the individuals in micro-economic structures in the discrete frame. Copyright © 2020 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved

关键词： Probability distributions

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Simulations of particle transport inside bubbles using coupled interface and lagrangian tracking approaches 18

Simulations of particle transport inside bubbles using coupl...

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18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019

作者： Zhu, Min Dehbi, A. Sato, Y. Niceno, B. School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Laboratory for Scientific Computing and Modelling Paul Scherrer Institut Villigen5232 Switzerland

Fission product aerosols may be released from nuclear degraded cores. Analyzing the retention of these aerosols allows the quantification of the amount of radioactivity that could reach the environment. In most LWR severe accident scenarios, the transport paths of aerosols include transits through stagnant water pools. Hence, it is important to develop accurate tools to simulate aerosol removal inside these pools. Predicting particle retention by pools is today mostly done with 1-D models that are too simplified to be reliable. Recently however, CFD has become a reasonably mature tool for simulating simple bubble hydrodynamics using Interface Tracking (IT) approaches. In this study, we take the IT methodology one step further by combining it with a Lagrangian Particle Tracking (LPT) model to determine the trajectories and removal of solid particles entrained within the bubble. We use the in-house IT multiphase code "Parallel SImulator of BOILing phenomena" (PSI-BOIL) in which we implement the LPT model. Slow momentum particle-laden air is fed from the bottom of a water pool through an injector. Bubbles grow and detach periodically from the injector. Particles move inside the bubble due to drag as well as gravity. A fraction of particles with significant inertia drift all the way to the interface and are lost to the water pool, while the lightest particles circulate around the bubble until they leave computational domain. A quantitative correlation of the particle deposition fraction versus Stokes number is proposed. © 2019 American Nuclear Society. All rights reserved.

关键词： Aerosols

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Computational evaluation of natural compounds as potential inhibitors of human PEPCK-M: An alternative for lung cancer therapy

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Advances and Applications in Bioinformatics and Chemistry 2019年 12卷 15-32页

作者： Baptista, Luiz Phillippe R. Sinatti, Vanessa V. C. da Silva, Joao H. M. Dardenne, Laurent Emmanuel Guimarães, Ana Carolina Laboratory for Functional Genomics and Bioinformatics Fiocruz Oswaldo Cruz Institute Rio de Janeiro RJ Brazil Group for Computational Modelling Fiocruz Oswaldo Cruz Foundation Eusébio CE Brazil Group for Molecular Modelling of Biologic Systems National Laboratory of Scientific Computing Petrópolis RJ Brazil

Background: Lung cancer is the leading cause of cancer-related death worldwide. Among its subtypes, non-small cell lung cancer (NSCLC) is the most common. Recently, the mitochondrial isoform of the enzyme phosphoenolpyruvate carboxykinase (HsPEPCK-M) was identified as responsible for the metabolic adaptation in the NSCLC allowing tumor growth even under conditions of glucose deficiency. This adaptation is possible due to the role of HsPEPCK-M in gluconeogenesis, converting the oxaloacetate to phosphoenolpyruvate in the presence of GTP, which plays an important role in the energetic support of these tumors. In this context, it was shown that the inhibition or knockdown of this enzyme was able to induce apoptosis in NSCLC under low glucose conditions. Purpose: In this study, novel putative inhibitors were proposed for the human PEPCK-M (HsPEPCK-M) based on a computer-aided approach. Methods: Comparative modeling was used to generate 3D models for HsPEPCK-M. Subsequently, the set of natural compounds of the ZINC database was screened against HsPEPCK-M models using structure-based pharmacophore modeling and molecular docking approaches. The selected compounds were evaluated according to its chemical diversity and clustered based on chemical similarity. Results: The pharmacophore hypotheses, generated based on known PEPCK inhibitors, were able to select 7,124 candidate compounds. These compounds were submitted to molecular docking studies using three conformations of HsPEPCK-M generated by comparative modeling. The aim was to select compounds with high predicted binding affinity for at least one of the conformations of HsPEPCK-M. After molecular docking, 612 molecules were selected as potential inhibitors of HsPEPCK-M. These compounds were clustered according to their structural similarity. Chemical profiling and binding mode analyses of these compounds allowed the proposal of four promising compounds: ZINC01656421, ZINC895296, ZINC00895535 and ZINC02571340. Conclusion:

关键词： Lung cancer Molecular docking Natural products PEPCK-M Pharmacophore modeling Virtual screening

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Learning algorithm of kohonen network with selection phase

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WSEAS Transactions on Computers 2012年第11期11卷 387-396页

作者： Ettaouil, Mohamed Abdelatifi, Essafi Belhabib, Fatima El Moutaouakil, Karim UFR: Scientific Computing and Computer Sciences Engineering Sciences Modelling and Scientific Computing Laboratory University Sidi Mohamed Ben Abdelah Fez Morocco

The learning algorithm of kohonen network realized away from any notion of class. So, the labelling phase is necessary to find the class associated to data. Generally, the size of the topological map is randomly chosen. Such choice effect the performance of the Kohonen algorithm. Consequently, the labelling phase becomes difficult to realize. To overcome this problem, we add to learning Kohonen algorithm a phase called selection stage. This phase is based on a function called selection function;to construct, we use a sub-set of the data set. In addition, we divided the topological map on two parts: The first contains the used neurons;while the second one is formed by the unused ones. It should be noted that the size of the first and the second parts are modified by the use of the selection function. To compare our method with the classical one, some experiments results are performed.

关键词： Learning algorithms

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RKDG Methods with Multi-resolution WENO Limiters for Solving Steady-State Problems on Triangular Meshes

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Communications on Applied Mathematics and Computation 2024年第3期6卷 1575-1599页

作者： Jun Zhu Chi-Wang Shu Jianxian Qiu State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles(NUAA) MIITNanjing University of Aeronautics and AstronauticsNanjing 210016JiangsuChina Division of Applied Mathematics Brown UniversityProvidenceRI 02912USA School of Mathematical Sciences and Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific ComputingXiamen UniversityXiamen 361005FujianChina

In this paper, we design high-order Runge-Kutta discontinuous Galerkin (RKDG) methods with multi-resolution weighted essentially non-oscillatory (multi-resolution WENO) limiters to compute compressible steady-state problems on triangular meshes. A troubled cell indicator extended from structured meshes to unstructured meshes is constructed to identify triangular cells in which the application of the limiting procedures is required. In such troubled cells, the multi-resolution WENO limiting methods are used to the hierarchical L^(2) projection polynomial sequence of the DG solution. Through using the RKDG methods with multi-resolution WENO limiters, the optimal high-order accuracy can be gradually reduced to first-order in the triangular troubled cells, so that the shock wave oscillations can be well suppressed. In steady-state simulations on triangular meshes, the numerical residual converges to near machine zero. The proposed spatial reconstruction methods enhance the robustness of classical DG methods on triangular meshes. The good results of these RKDG methods with multi-resolution WENO limiters are verified by a series of two-dimensional steady-state problems.

关键词： RKDG method Steady-state problem Multi-resolution WENO limiter Triangular mesh Machine zero

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Genetic algorithm for neural network architecture optimization 3

Genetic algorithm for neural network architecture optimizati...

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3rd IEEE International Conference on Logistics Operations Management, GOL 2016

作者： Idrissi, Mohammed Amine Janati Ramchoun, Hassan Ghanou, Youssef Ettaouil, Mohamed Modelling and Scientific Computing Laboratory Faculty of Sciences and Technology Sidi Mohammed Ben Abdellah University Fez Morocco Team TIM High School of Technology Moulay Ismail University Meknes Morocco

ISBN: (纸本)9781467385718

The optimization of architecture of feed-forward neural networks is a complex task of high importance in supervised learning because it has a great impact on the convergence of learning methods. In this paper, we propose a multi-objective mathematical formulation in order to determine the optimal number of hidden layers, the number of neurons in each layer and good values of weights. We will solve our mathematical modeling using a hybridation of the famous genetic algorithm and the back-prop training algorithm. For evaluating our approach, we apply it to benchmark classification problems data-iris, seed, and wine. The obtained results demonstrated the effectiveness of the proposed approach. © 2016 IEEE.

关键词： Multiobjective optimization

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Implementing noncollective parallel I/O in cluster environments using Active Message communication

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Cluster computing 1999年第4期2卷 271-279页

作者： Nieplocha, Jarek Dachsel, Holger Foster, Ian Pacific Northwest National Laboratory Richland USA Scientific Computing & Modelling HV Amsterdam The Netherlands Argonne National Laboratory Argonne USA

A cost‐effective secondary storage architecture for parallel computers is to distribute storage across all processors, which then engage in either computation or I/O, depending on the demands of the moment. A difficulty associated with this architecture is that access to storage on another processor typically requires the cooperation of that processor, which can be hard to arrange if the processor is engaged in other computation. One partial solution to this problem is to require that remote I/O operations occur only via collective calls. In this paper, we describe an alternative approach based on the use of single‐sided communication operations such as Active Messages. We present an implementation of this basic approach called Distant I/O and present experimental results that quantify the low‐level performance of DIO mechanisms. This technique is exploited to support noncollective parallel shared file model for a large out‐of‐core scientific application with very high I/O bandwidth requirements. The achieved performance exceeds by a wide margin the performance of a well equipped PIOFS parallel filesystem on the IBM SP.

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DISCRETE ENERGY ANALYSIS OF THE THIRD-ORDER VARIABLE-STEP BDF TIME-STEPPING FOR DIFFUSION EQUATIONS

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Journal of Computational Mathematics 2023年第2期41卷 325-344页

作者： Hong-lin Liao Tao Tang Tao Zhou Department of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles(NUAA) MIITNanjing 211106China Division of Science and Technology BNU-HKBU United International CollegeZhuhai 519087China Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing100190China

This is one of our series works on discrete energy analysis of the variable-step BDF *** this part,we present stability and convergence analysis of the third-order BDF(BDF3)schemes with variable steps for linear diffusion equations,see,e.g.,[SIAM ***.,58:2294-2314]and[***.,90:1207-1226]for our previous works on the BDF2 *** this aim,we first build up a discrete gradient structure of the variable-step BDF3 formula under the condition that the adjacent step ratios are less than 1.4877,by which we can establish a discrete energy dissipation ***-robust stability and convergence analysis in the L^(2) norm are then *** the mesh robustness means that the solution errors are well controlled by the maximum time-step size but independent of the adjacent time-step *** also present numerical tests to support our theoretical results.

关键词： Diffusion equations Variable-step third-order BDF scheme Discrete gradient structure Discrete orthogonal convolution kernels Stability and convergence

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Impact of population balance model on subcooled flow boiling simulation 20

Impact of population balance model on subcooled flow boiling...

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20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023

作者： Vlček, Daniel Sato, Yohei Faculty of Nuclear Sciences and Physical Engineering Czech Technical University V Holesovickach 2 Prague180 00 Czech Republic Laboratory for Scientific Computing and Modelling Paul Scherrer Institut PSI Villigen5232 Switzerland

ISBN: (纸本)9780894487934

This paper presents two modifications of Eulerian CFD (Computational Fluid Dynamics) model to predict subcooled boiling flows in the DEBORA experiment, the conditions of Freon-R12 corresponding to those in PWRs (Pressurized Water Reactors). Literature study reveals that the experimental data, which were used for CFD validation, were limited to low void fraction cases ( © 2023 Proceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023. All rights reserved.

关键词： Pressurized water reactors

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