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6th International Conference on Simulation and Modeling Methodologies, Technologies and Applications, SIMULTECH 2016

作者： Clees, Tanja Hornung, Nils Nikitin, Igor Nikitina, Lialia Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven Sankt Augustin53754 Germany

ISBN: (纸本)9789897581991

We consider generalized resistive systems, comprising linear Kirchhoff equations and non-linear element equations, depending on the flow through the element and on two adjacent nodal variables. The derivatives of the element equation should possess a special signature. For such systems we prove the global non-degeneracy of the Jacobi matrix and the applicability of globally convergent solution tracing algorithms. We show that the stationary problems in gas transport networks belong to this generalized resistive type. We apply the tracing algorithm to several realistic networks and compare its performance with a generic Newton solver. © Copyright 2016 by SCITEPRESS - Science and Technology Publications, Lda. All rights reserved.

关键词： Linear systems

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MYNTS: Multi-physics network simulator 6

MYNTS: Multi-physics network simulator

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6th International Conference on Simulation and Modeling Methodologies, Technologies and Applications, SIMULTECH 2016

作者： Clees, Tanja Cassirer, Kläre Hornung, Nils Klaassen, Bernhard Nikitin, Igor Nikitina, Lialia Suter, Robin Torgovitskaia, Inna Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven Sankt Augustin53754 Germany

ISBN: (纸本)9789897581991

We present a generic approach for the simulation of transport networks, where the steps of physical modeling and numerical simulation are effectively separated. The model is described by a list of physical equations and inequalities as problem constraints for non-linear programming (NLP). This list is translated to the language of expression trees and is made accessible for the numerical solution by standard NLP solvers. Various problem types can be solved in this way, including stationary and transient network simulation, feasibility analysis and energy-saving optimization. The simulation is provided for different disciplines, such as gas transport, water supply and electric power networks. We demonstrate the implementation of this approach in our multiphysics network simulator. © Copyright 2016 by SCITEPRESS - Science and Technology Publications, Lda. All rights reserved.

关键词： Linear systems

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ATK-ForceField: A new generation molecular dynamics software package

arXiv

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arXiv 2017年

作者： Schneider, Julian Hamaekers, Jan Chill, Samuel T. Smidstrup, Søren Bulin, Johannes Thesen, Ralph Blom, Anders Stokbro, Kurt QuantumWise A/S Fruebjergvej 3 CopenhagenDK-2100 Denmark Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt Augustin53754 Germany

ATK-ForceField is a software package for atomistic simulations using classical interatomic potentials. It is implemented as a part of the Atomistix ToolKit (ATK), which is a Python programming environment that makes it easy to create and analyze both standard and highly customized simulations. This paper will focus on the atomic interaction potentials, molecular dynamics, and geometry optimization features of the software, however, many more advanced modeling features are available. The implementation details of these algorithms and their computational performance will be shown. We present three illustrative examples of the types of calculations that are possible with ATK-ForceField: modeling thermal transport properties in a silicon germanium crystal, vapor deposition of selenium molecules on a selenium surface, and a simulation of creep in a copper polycrystal. Copyright © 2017, The Authors. All rights reserved.

关键词： Software packages

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A representer theorem for deep kernel learning

arXiv

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arXiv 2017年

作者： Bohn, Bastian Griebel, Michael Rieger, Christian Institute for Numerical Simulation University of Bonn Wegelerstr. 6 Bonn53115 Germany Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt Augustin53754 Germany

In this paper we provide a finite-sample and an infinite-sample representer theorem for the concatenation of (linear combinations of) kernel functions of reproducing kernel Hilbert spaces. These results serve as mathematical foundation for the analysis of machine learning algorithms based on compositions of functions. As a direct consequence in the finite-sample case, the corresponding infinite-dimensional minimization problems can be recast into (nonlinear) finite-dimensional minimization problems, which can be tackled with nonlinear optimization algorithms. Moreover, we show how concatenated machine learning problems can be reformulated as neural networks and how our representer theorem applies to a broad class of state-of-the-art deep learning methods. Copyright © 2017, The Authors. All rights reserved.

关键词： Sampling

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Benchmark gas distribution network for cross-sectoral applications

Benchmark gas distribution network for cross-sectoral applic...

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International Energy and Sustainability Conference (IESC)

作者： Christian Brosig Silvan Fassbender Eberhard Waffenschmidt Sebastian Janocha Bernhard Klaassen Cologne Institute of Renewable Energy (ClRE) Cologne University of Applied Sciences Cologne Germany Rheinische NETZGesellschaft mbH (RNG) Cologne Germany Fraunhofer Institute for Algorithms and Scientific Computing SCAI Sankt Augustin Germany

Cross-sectoral coupling of energy systems could provide the necessary flexibility for future energy systems with a high share of renewable energies. The gas grid implies large storage capacities and thus promises an economically attractive balance for fluctuating energy sources. A benchmark gas distribution network, coupled to the CIGRE benchmark network for electricity is presented within this paper, to universally investigate the impacts on gas grid infrastructure. The network includes interconnected meshed and radial topologies for both low and medium pressure gas networks. They have been synthesized from existing real networks in cooperation with the Rheinische NETZGesellschaft mbH. Applications range from analyzing network impacts of widespread CHP or fuel cell implementation, over comparing the cost-effectiveness of different future pathways between expansion and decommissioning of the gas grid network, to analyzing the impacts of distributed injection of renewable gas. The overall aim is to build a complete network benchmark for an integral cross-sectoral energy system including also heat.

关键词： Steel Benchmark testing Fuel cells Hydrogen Cogeneration Regulators Couplings

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An efficient geosciences workflow on multi-core processors and GPUs:a case study for aerosol optical depth retrieval from MODIS satellite data

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International Journal of Digital Earth 2016年第8期9卷 748-765页

作者： Jia Liu Dustin Feld Yong Xue Jochen Garcke Thomas Soddemann Peiyuan Pan Key Laboratory of Digital Earth Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingChina Faculty of Life Sciences and Computing London Metropolitan UniversityLondonUK Fraunhofer Institute for Algorithms and Scientific Computing SCAI Sankt AugustinGermany Institute for Numerical Simulation University of BonnBonnGermany University of Chinese Academy of Sciences BeijingChina Department of Computer Science University of CologneCologneGermany

Quantitative remote sensing retrieval algorithms help understanding the dynamic aspects of Digital ***,the Big Data and complex models in Digital Earth pose grand challenges for computation *** this article,taking the aerosol optical depth(AOD)retrieval as a study case,we exploit parallel computing methods for high efficient geophysical parameter *** present an efficient geocomputation workflow for the AOD calculation from the Moderate Resolution Imaging Spectroradiometer(MODIS)satellite *** to their individual potential for parallelization,several procedures were adapted and implemented for a successful parallel execution on multicore processors and Graphics Processing Units(GPUs).The benchmarks in this paper validate the high parallel performance of the retrieval workflow with speedups of up to 5.x on a multi-core processor with 8 threads and 43.x on a *** specifically address the time-consuming model retrieval part,hybrid parallel patterns which combine the multicore processor’s and the GPU’s compute power were implemented with static and dynamic workload distributions and evaluated on two systems with different CPU–GPU *** is shown that only the dynamic hybrid implementation leads to a greatly enhanced overall exploitation of the heterogeneous hardware environment in varying circumstances.

关键词： Digital earth highperformance computing GPU multi-core hybrid parallel pattern aerosol optical depth retrieval workflow

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MYNTS: Multi-physics network simulator

MYNTS: Multi-physics network simulator

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International Conference on Simulation and Modeling Methodologies, Technologies and Applications (SIMULTECH)

作者： Tanja Clees Klare Cassirer Nils Hornung Bernhard Klaassen Igor Nikitin Lialia Nikitina Robin Suter Inna Torgovitskaia Fraunhofer Institute for Algorithms and Scientific Computing Sankt Augustin Germany

ISBN: (纸本)9781509058945

关键词： Mathematical model Optimization Computational modeling Numerical models Reactive power Software algorithms Compressors

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A Globally Convergent Method for Generalized Resistive Systems and its Application to Stationary Problems in Gas Transport Networks

A Globally Convergent Method for Generalized Resistive Syste...

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International Conference on Simulation and Modeling Methodologies, Technologies and Applications

作者： Tanja Clees Nils Hornung Igor Nikitin Lialia Nikitina Fraunhofer Institute for Algorithms and Scientific Computing Schloss Birlinghoven 53754 Sankt Augustin Germany

ISBN: (纸本)9781509058945

关键词： Non-linear Systems Globally Convergent Methods Gas Transport Networks

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ϵ-dimension in infinite dimensional hyperbolic cross approximation and application to parametric elliptic PDEs

arXiv

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arXiv 2017年

作者： Dũng, Dinh Griebel, Michael Huy, Vu Nhat Rieger, Christian Information Technology Institute Vietnam National University Hanoi 144 Xuan Thuy Cau Giay Hanoi Viet Nam Institute for Numerical Simulation Bonn University Wegelerstrasse 6 Bonn53115 Germany Fraunhofer Institute for Algorithms and Scientific Computing Scai Schloss Birlinghoven Sankt Augustin53754 Germany College of Science Vietnam National University Hanoi 334 Nguyen Trai Thanh Xuan Hanoi Viet Nam

In this article, we present a cost-benefit analysis of the approximation in tensor products of Hilbert spaces of Sobolev-analytic type. The Sobolev part is defined on a finite dimensional domain, whereas the analytical space is defined on an infinite dimensional domain. As main mathematical tool, we use the ϵ-dimension of a subset in a Hilbert space. The ϵ-dimension gives the lowest number of linear information that is needed to approximate an element from the set in the norm of the Hilbert space up to an accuracy ϵ > 0. From a practical point of view this means that we a priori fix an accuracy and ask for the amount of information to achieve this accuracy. Such an analysis usually requires sharp estimates on the cardinality of certain index sets which are in our case infinite-dimensional hyperbolic crosses. As main result, we obtain sharp bounds of the ϵ-dimension of the Sobolev-analytic-type function classes which depend only on the smoothness differences in the Sobolev spaces and the dimension of the finite dimensional domain where these spaces are defined. This implies in particular that, up to constants, the costs of the infinite dimensional (analytical) approximation problem is dominated by the finite-variate Sobolev approximation problem. We demonstrate this procedure with an examples of functions spaces stemming from the regularity theory of parametric partial differential equations. Copyright © 2017, The Authors. All rights reserved.

关键词： Stochastic systems

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Status of system-AMG for reservoir simulation applications

Status of system-AMG for reservoir simulation applications

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SPE Reservoir Simulation Symposium 2015

作者： Gries, Sebastian Plum, Hans-Joachim Fraunhofer Institute for Algorithms and Scientific Computing SCAI Germany

ISBN: (纸本)9781510800618

Algebraic multigrid (AMG) methods for directly solving coupled systems of partial differential equations (PDEs) have been extensively used in various types of numerical simulations in engineering. A necessary condition for its efficient applicability is the simulation process being driven by elliptic components. In reservoir simulation the pressure, described by Darcy's law, is known to drive the process and hence System-AMG should be applicable and outperform classical solvers. In the context of adaptive and fully implicit reservoir simulations, the linearization of balance equations results in linear systems of equations that can be challenging. This makes it crucial to exploit all physical information from the full system to construct a robust AMG strategy and to extend it to more complex simulations than Black-Oil. At the same time, the full set of information helps to get the best out of AMG. Just as with multigrid in general, System- AMG provides a framework for combining algorithmic modules rather than a fixed solution algorithm. The adaptation of the solution strategy to the concrete class of applications is the key to obtain the best performance. Finally, System-AMG does not only allow for choosing more efficient algorithmic strategies, but also for exploiting parallelism in an optimized way, regardless of the simulation code being parallelized or not. Because the linear solver time is typically far dominating, even serial simulators can immediately and substantially benefit from MPI parallelism. Copyright © 2015 Society of Petroleum Engineers.

关键词： Linear systems

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