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作者： Kraus, Jiri Förster, Malte Brandes, Thomas Soddemann, Thomas Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven 53754 Sankt Augustin Germany

In this paper, we describe the implementation of an AMG solver for a hybrid cluster that exploits distributed and shared memory parallelization and uses the available GPU accelerators on each node. This solver has been written by using LAMA (Library for Accelerated Math Applications). This library does not only provide an easy-to-use framework for solvers that might run on different devices with different matrix formats, but also comes with features to optimize and hide communication and memory transfers between CPUs and GPUs. These features are explained and their impact on the efficiency of the AMG solver is shown in this paper. The benchmark results show that an efficient use of hybrid clusters is even possible for multi-level methods like AMG where fast solutions are needed on all levels for multiple problem sizes. © 2012 Springer-Verlag.

关键词： Program processors

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Preconditioning for efficiently applying algebraic multigrid in fully implicit reservoir simulations

Preconditioning for efficiently applying algebraic multigrid...

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SPE Reservoir Simulation Symposium 2013

作者： Gries, Sebastian Stüben, Klaus Brown, Geoffrey L. Chen, Dingjun Collins, David A. Fraunhofer Institute for Algorithms and Scientific Computing SCAI Germany Computer Modelling Group Ltd. Canada

ISBN: (纸本)9781627480246

Fully implicit petroleum reservoir simulations result in huge, often very ill-conditioned linear systems of equations to solve for different unknowns, for example, pressure and saturations. It is well known that the full system matrix contains both hyperbolic as well as nearly elliptic sub-systems. Since the solution of the coupled system is mainly determined by the solution of their elliptic (typically pressure) components, (CPR-type) two-stage preconditioning methods still belong to the most popular approaches to tackle such coupled systems. After a suitable extraction and decoupling, the numerically most costly step in such two-stage methods consists in solving these elliptic sub-systems. It is known that algebraic multigrid (AMG) provides a technique to solve elliptic linear equations very efficiently. The main advantage of AMG-based solvers - their numerical scalability - makes them particularly efficient for solving huge linear systems. Depending on the application, the system's properties range from simple to highly indefinite. Unfortunately decoupling pressure and saturation related parts may introduce further difficulties. Consequently, in complex industrial simulations, the application of AMG to elliptic sub-systems might not be straightforward. In fact, an important goal in defining an efficient two-stage preconditioning strategy consists in extracting elliptic sub-systems that are suitable for an efficient AMG solution and, at the same time, ensure a fast overall convergence of the two-stage approach. The importance of this will be demonstrated for several industrial cases. In particular, some of these cases are very hard to solve by AMG if applied in a standard way. Preliminary results for a CPR-type coupling of SAMG to CMG's PARASOL, a variable degree variable ordering ILU preconditioner using FGMRES, are compared to using PARASOL by itself. Alternative preconditioning operators will be presented giving elliptic sub-systems which are not only more suit

关键词： Iterative methods

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Multiscale simulation of ion migration for battery systems

Multiscale simulation of ion migration for battery systems

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21st International Materials Research Congress, IMRC 2012

作者： Neuen, Christian Griebel, Michael Hamaekers, Jan Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven 53754 Sankt Augustin Germany Institute for Numerical Simulation Bonn University Wegelerstr. 6 53115 Bonn Germany

ISBN: (纸本)9781632661258

In this paper we describe a multi-scale approach to ion migration processes, which involves a bridging from the atomic scale to the macroscopic scale. To this end, the diffusion coefficient of a material i.e. a macroscopic physical quantity, will be appropriately determined from molecular dynamics simulations on the microscale. This way, performance predictions become possible prior to material synthesis. However, standard methods produce in general wrong results for ensemble setups which correspond to battery or capacitor applications. We introduce a novel method to derive correct values also for such problems. These values are then used in a macroscopic system of partial differential equation (Poisson-Nernst-Planck system) for the numerical simulation of ion migration in a battery. © 2013 Materials Research Society.

关键词： Molecular dynamics

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Analysis of bulky crash simulation results: Deterministic and stochastic aspects

Advances in Intelligent Systems and Computing

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Advances in Intelligent Systems and computing 2013年 197卷 225-237页

作者： Clees, Tanja Nikitin, Igor Nikitina, Lialia Thole, Clemens-August Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven Sankt Augustin53754 Germany

ISBN: (纸本)9783642343353

Crash simulation results show both deterministic and stochastic behavior. For optimization in automotive design it is very important to distinguish between effects caused by variation of simulation parameters and effects triggered, for example, by buckling phenomena. We propose novel methods for the exploration of a simulation database featuring non-linear multidimensional interpolation, tolerance prediction, sensitivity analysis, robust multiobjective optimization as well as reliability and causal analysis. The methods are highly optimized for handling bulky data produced by modern crash simulators. The efficiency of these methods is demonstrated for industrially relevant benchmark cases. © Springer-Verlag Berlin Heidelberg 2013.

关键词： Multiobjective optimization

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From integrative disease modeling to predictive, preventive, personalized and participatory (P4) medicine

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EPMA Journal 2014年第1期5卷 1-1页

作者： Erfan Younesi Martin Hofmann-Apitius Department of Bioinformatics Fraunhofer Institute for Algorithms and Scientific Computing (SCAI) Schloss Birlinghoven Sankt Augustin Germany Rheinische Friedrich-Wilhelms-Universität Bonn Bonn-Aachen International Center for IT Bonn Germany

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Multiscale Simulation of Ion Migration for Battery Systems

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MRS Online Proceedings Library (OPL) 2013年第1期1535卷 mmm2012-a-0099-mmm2012-a-0099页

作者： Christian Neuen Michael Griebel Jan Hamaekers Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven 53754 Sankt Augustin Germany Institute for Numerical Simulation Bonn University Wegelerstr. 6 53115 Bonn Germany

In this paper we describe a multi-scale approach to ion migration processes, which involves a bridging from the atomic scale to the macroscopic scale. To this end, the diffusion coefficient of a material i.e. a macroscopic physical quantity, will be appropriately determined from molecular dynamics simulations on the microscale. This way, performance predictions become possible prior to material synthesis. However, standard methods produce in general wrong results for ensemble setups which correspond to battery or capacitor *** introduce a novel method to derive correct values also for such problems. These values are then used in a macroscopic system of partial differential equation (Poisson-Nernst-Planck system) for the numerical simulation of ion migration in a battery.

关键词： diffusion simulation kinetics

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Bel networks derived from qualitative translations of BioNLP shared task annotations

Bel networks derived from qualitative translations of BioNLP...

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2013 Workshop on Biomedical Natural Language Processing, BioNLP 2013 at the 51st Annual Meeting of the Association for Computational Linguistics, ACL 2013

作者： Fluck, Juliane Klenner, Alexander Madan, Sumit Ansari, Sam Bobic, Tamara Hoeng, Julia Hofmann-Apitius, Martin Peitsch, Manuel C. Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven Sankt Augustin Germany Philip Morris International RandD Philip Morris Products S.A. Quai Jeanrenaud 5 Neuchâtel2000 Switzerland Bonn-Aachen International Centre for Information Technology Dahlmannstr. 2 Bonn Germany

ISBN: (纸本)9781937284541

Interpreting the rapidly increasing amount of experimental data requires the availability and representation of biological knowledge in a computable form. The Biological expression language (BEL) encodes the data in form of causal relationships, which describe the association between biological events. BEL can successfully be applied to large data and support causal reasoning and hypothesis generation. With the rapid growth of biomedical literature, automated methods are a crucial prerequisite for handling and encoding the available knowledge. The BioNLP shared tasks support the development of such tools and provide a linguistically motivated format for the annotation of relations. On the other hand, BEL statements and the corresponding evidence sentences might be a valuable resource for future BioNLP shared task training data generation. In this paper, we briefly introduce BEL and investigate how far BioNLP-shared task annotations could be converted to BEL statements and in such a way directly support BEL statement generation. We present the first results of the automatic BEL statement generation and emphasize the need for more training data that captures the underlying biological meaning. © 2013 Association for Computational Linguistics

关键词： Encoding (symbols)

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Loewy Decomposition of Linear Differential Equations 1

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丛书名： Texts & Monographs in Symbolic Computation

2012年

作者： Fritz Schwarz

ISBN: (数字)9783709112861

ISBN: (纸本)3709112850

The central subject of the book is the generalization of Loewy's decomposition - originally introduced by him for linear ordinary differential equations - to linear partial differential equations. Equations for a single function in two independent variables of order two or three are comprehensively discussed. A complete list of possible solution types is given. Various ad hoc results available in the literature are obtained algorithmically. The border of decidability for generating a Loewy decomposition are explicitly stated. The methods applied may be generalized in an obvious way to equations of higher order, in more variables or systems of such equations.

关键词： Symbolic and Algebraic Manipulation Differential Equations Mathematical and Computational Engineering Applications

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Modern information technology: Information visualization, virtual environment, neo-geography, tangible images

Scientific Visualization

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scientific Visualization 2013年第4期5卷 1-17页

作者： Aleshin, A. Afanasiev, V. Brusentsev, P. Eremchenko, E. Klimenko, A. Klimenko, S. Nikitin, I. Nikitina, L. Pestrikov, V. Sourin, A. Sourina, O. Moscow Russia Barco Russia and CIS Moscow Russia Neo-geography Group Protvino Russia Institute of Computing for Physics and Technology Protvino Russia Fraunhofer Institute for Algorithms and Scientific Computing SCAI Germany Nanyang Technological University Singapore Singapore Fraunhofer Interactive Digital Media at NTU Singapore Singapore

The ever increasing complexity of the physical phenomena studied in scientific and engineering disciplines , requires the development of new approaches and powerful technique for processing and analysis of complex data. scientific Visualization developing methods and tools for understanding the problems to be solved by bringing in a person's ability to see and perceive the image. The article deals with the preconditions of occurrence of this scientific field, the stages of its formation as a scientific discipline and major achievements. Shows the transition from technology to render virtual environment. Currently, scientific visualization is quite complete scientific discipline. Purpose of virtual environments is to provide users with a virtual workspace, in which they can observe and investigate create the virtual real-time data, models and the scenes. Presents selected results of the development of scientific visualization and virtual environment from the Moscow institute of Physics and Technology and the institute of computing for Physics and Technology in cooperation with research centers in Germany and Singapore. In conclusion ascertained advantages of visualization technologies and virtual environments to improve the efficiency of fundamental research, to meet the challenges of science, education and industry. Promising areas of research in this subject area are information visualization , visual analytics, a new man-machine interfaces based on haptic devices and tangible images.

关键词： Data visualization

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Sparse Grids and Applications

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2012年

作者： Jochen Garcke Michael Griebel

ISBN: (纸本)9783642317026

In the recent decade, there has been a growing interest in the numerical treatment of high-dimensional problems. It is well known that classical numerical discretization schemes fail in more than three or four dimensions due to the curse of dimensionality. The technique of sparse grids helps overcome this problem to some extent under suitable regularity assumptions. This discretization approach is obtained from a multi-scale basis by a tensor product construction and subsequent truncation of the resulting multiresolution series expansion. This volume of LNCSE is a collection of the papers from the proceedings of the workshop on sparse grids and its applications held in Bonn in May 2011. The selected articles present recent advances in the mathematical understanding and analysis of sparse grid discretization. Aspects arising from applications are given particular attention.

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