检索结果-内蒙古大学图书馆

The octet rule in chemical space: generating virtual molecules

2016年

作者： Workshop on Sparse Grids and Applications

来源：内蒙古大学图书馆图书评论

学校读者我要写书评

暂无评论

arXiv 2017年

作者： Hamaekers, Rafel Maaß, Astrid Hamaekers, Jan Fraunhofer Institute Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt AugustinD-53754 Germany

We present a generator of virtual molecules that selects valid chem- istry on the basis of the octet rule. Also, we introduce a mesomer group key that allows a fast detection of duplicates in the generated *** to existing approaches, our model is simpler and faster, generates new chemistry and avoids invalid chemistry. Its versatility is illustrated by the correct generation of molecules containing third-row elements and a surprisingly adept handling of complex boron chem- *** any empirical parameters, our model is designed to be valid also in unexplored regions of chemical space. One first unex- pected finding is the high prevalence of dipolar structures among gen- erated molecules. Copyright © 2017, The Authors. All rights reserved.

关键词： Molecules

A knowledge-based surrogate modeling approach for cup drawing with limited data

学校读者我要写书评

暂无评论

IOP Conference Series: Materials Science and Engineering 2019年第1期651卷

作者： L Morand D Helm R Iza-Teran J Garcke Fraunhofer Institute for Mechanics of Materials IWM Wöhlerstraße 11 Freiburg 79108 Germany Fraunhofer Center for Machine Learning and Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt Augustin 53754 Germany Institute for Numerical Simulations University of Bonn Endenicher Allee 19b Bonn 53115 Germany

To predict the quality of a process outcome with given process parameters in real-time, surrogate models are often adopted. A surrogate model is a statistical model that interpolates between data points obtained either by process measurements or deterministic models of the process. However, in manufacturing processes the amount of useful data is often limited, and therefore setting up a sufficiently accurate surrogate model is challenging. The present contribution shows how to handle limited data in a surrogate modeling approach using the example of a cup drawing process. The purpose of the surrogate model is to classify the quality of the drawn cup and to predict its final geometry. These classification and regression tasks are solved via machine learning methods. The training data is sampled on a relatively wide range varying three parameters of a finite element simulation, namely sheet metal thickness, blank holder force, and friction. The geometrical features of the cup are extracted using domain knowledge. Besides this knowledge-based approach, an outlook is given for a data-driven surrogate modeling approach.

关键词：

Kernel-based stochastic collocation for the random two-phase navier-stokes equations

学校读者我要写书评

暂无评论

arXiv 2018年

作者： Griebel, M. Rieger, C. Zaspel, P. Institute for Numerical Simulation Bonn University Endenicher Allee 19b BonnD-53115 Fraunhofer Institute for Algorithms and Scientific Computing Scai Schloss Birlinghoven Sankt AugustinD-53754 Department of Mathematics Rwth Aachen University Schinkelstr. 2 AachenD-52062 Department of Mathematics and Computer Science University of Basel Spiegelgasse 1 Basel4051

In this work, we apply stochastic collocation methods with radial kernel basis functions for an uncertainty quantification of the random incompressible two-phase Navier-Stokes equations. Our approach is non-intrusive and we use the existing fluid dynamics solver NaSt3DGPF to solve the incompressible two-phase Navier-Stokes equation for each given realization. We are able to empirically show that the resulting kernel-based stochastic collocation is highly competitive in this setting and even outperforms some other standard methods. Copyright © 2018, The Authors. All rights reserved.

关键词： Viscous flow

Sparse Grids and Applications - Munich 2012

学校读者我要写书评

暂无评论

2016年

作者： Jochen Garcke Dirk Pflger

ISBN: (纸本)9783319381534

Sparse grids have gained increasing interest in recent years for the numerical treatment of high-dimensional problems. Whereas classical numerical discretization schemes fail in more than three or four dimensions, sparse grids make it possible to overcome the curse of dimensionality to some degree, extending the number of dimensions that can be dealt with. This volume of LNCSE collects the papers from the proceedings of the second workshop on sparse grids and applications, demonstrating once again the importance of this numerical discretization scheme. The selected articles present recent advances on the numerical analysis of sparse grids as well as efficient data structures, and the range of applications extends to uncertainty quantification settings and clustering, to name but a few examples.

关键词：

Orbital-enriched flat-top partition of unity method for the Schrödinger eigenproblem

学校读者我要写书评

暂无评论

arXiv 2018年

作者： Albrecht, Clelia Klaar, Constanze Pask, John Ernest Schweitzer, Marc Alexander Sukumar, N. Ziegenhagel, Albert Fraunhofer Institute for Algorithms and Scientific Computing SCAI Schloss Birlinghoven Sankt Augustin53757 Germany Physics Division Lawrence Livermore National Laboratory 7000 East Avenue LivermoreCA94550 United States Institute for Numerical Simulation Rheinische Friedrich-Wilhelms-Universität Wegelerstr. 6 Bonn53115 Germany Department of Civil and Environmental Engineering University of California DavisCA95616 United States

Quantum mechanical calculations require the repeated solution of a Schrödinger equation for the wavefunctions of the system, from which materials properties follow. Recent work has shown the effectiveness of enriched finite element type Galerkin methods at significantly reducing the degrees of freedom required to obtain accurate solutions. However, time to solution has been adversely affected by the need to solve a generalized rather than standard eigenvalue problem and the ill-conditioning of associated systems matrices. In this work, we address both issues by proposing a stable and efficient orbital-enriched partition of unity method to solve the Schrödinger boundary-value problem in a parallelepiped unit cell subject to Bloch-periodic boundary conditions. In the proposed partition of unity method, the three-dimensional domain is covered by overlapping patches, with a compactly-supported weight function associated with each patch. A key ingredient in our approach is the use of non-negative weight functions that possess the flat-top property, i.e., each weight function is identically equal to unity over some finite subset of its support. This flattop property provides a pathway to devise a stable approximation over the whole domain. On each patch, we use p-th degree orthogonal (Legendre) polynomials that ensure p-th order completeness, and in addition include eigenfunctions of the radial Schrödinger equation. Furthermore, we adopt a variational lumping approach to construct a (block-)diagonal overlap matrix that yields a standard eigenvalue problem for which there exist efficient eigensolvers. The accuracy, stability, and efficiency of the proposed method is demonstrated for the Schrödinger equation with a harmonic potential as well as a localized Gaussian potential. We show that the proposed approach delivers optimal rates of convergence in the energy, and the use of orbital enrichment significantly reduces the number of degrees of freedom for a given desired accu

关键词： Eigenvalues and eigenfunctions

ATK-ForceField: A new generation molecular dynamics software package

学校读者我要写书评

暂无评论

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

A representer theorem for deep kernel learning

学校读者我要写书评

暂无评论

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

Benchmark gas distribution network for cross-sectoral applications

学校读者我要写书评

暂无评论

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

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

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

学校读者我要写书评

暂无评论

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