检索结果-内蒙古大学图书馆

Bragg Gratings, Photosensitivity and Poling in Glass Waveguides and Materials, BGPPM 2018

作者： Brehler, Marius Schirwon, Malte Göddeke, Dominik Krummrich, Peter M. TU Dortmund Chair for High Frequency Technology Dortmund44227 Germany University of Stuttgart Institute for Applied Analysis and Numerical Simulation Stuttgart70569 Germany

We discuss the GPU-acceleration of MDM transmission system simulations and how the required memory can be drastically reduced to simulate a high number of modes. Furthermore, we show how to reduce the runtime. © ... 详细信息

ISBN: (纸本)9781943580439

关键词： Program processors

来源：评论

学校读者我要写书评

暂无评论

Minisymposium 5: Feti, balancing, and related hybrid domain decomposition methods

引用

17th International Conference on Domain Decomposition Methods

作者： Klawonn, Axel Widlund, Olof B. Wohlmuth, Barbara University of Duisburg-Essen Department of Mathematics Germany Courant Institute New York University United States University of Stuttgart Institute for Applied Analysis and Numerical Simulation Germany

来源：评论

学校读者我要写书评

暂无评论

A particle-based multiscale solver for compressible liquid-vapor flow

arXiv

引用

arXiv 2018年

作者： Magiera, Jim Rohde, Christian University of Stuttgart Institute for Applied Analysis and Numerical Simulation

To describe complex flow systems accurately, it is in many cases important to account for the properties of fluid flows on a microscopic scale. In this work, we focus on the description of liquid-vapor flow with a sharp interface between the phases. The local phase dynamics at the interface can be interpreted as a Riemann problem for which we develop a multiscale solver in the spirit of the heterogeneous multiscale method (HMM) [7], using a particle-based microscale model to augment the macroscopic two-phase flow system. The application of a microscale model makes it possible to use the intrinsic properties of the fluid at the microscale, instead of formulating (ad-hoc) constitutive relations. Copyright © 2018, The Authors. All rights reserved.

关键词： Partial differential equations

来源：评论

学校读者我要写书评

暂无评论

Greedy kernel methods for accelerating implicit integrators for parametric ODEs

arXiv

引用

arXiv 2018年

作者： Brunnette, .T. Santin, .G. Haasdonk, .B. Institute for Applied Analysis and Numerical Simulation University of Stuttgart

We present a novel acceleration method for the solution of para-metric ODEs by single-step implicit solvers by means of greedy kernel-based surrogate models. In an offline phase, a set of trajectories is precomputed with a high-Accuracy ODE solver for a selected set of parameter samples, and used to train a kernel model which predicts the next point in the trajectory as a function of the last one. This model is cheap to evaluate, and it is used in an online phase for new parameter samples to provide a good initialization point for the non-linear solver of the implicit integrator. The accuracy of the surrogate reflects into a reduction of the number of iterations until convergence of the solver, thus providing an overall speedup of the full simulation. Interestingly, in addition to providing an acceleration, the accuracy of the solution is maintained, since the ODE solver is still used to guar-antee the required precision. Although the method can be applied to a large variety of solvers and different ODEs, we will present in details its use with the Implicit Euler method for the solution of the Burgers equation, which results to be a meaningful test case to demonstrate the methods features. Copyright © 2018, The Authors. All rights reserved.

关键词： Ordinary differential equations

来源：评论

学校读者我要写书评

暂无评论

Robust and Efficient Preconditioners for Stokes–Darcy Problems 10th

Robust and Efficient Preconditioners for Stokes–Darcy Pro...

引用

10th International Symposium on Finite Volumes for Complex Applications, FVCA10 2023

作者： Strohbeck, Paula Riethmüller, Cedric Göddeke, Dominik Rybak, Iryna Institute of Applied Analysis and Numerical Simulation University of Stuttgart Pfaffenwaldring 57 Stuttgart70569 Germany Stuttgart Centre for Simulation Science University of Stuttgart Allmandring 5b Stuttgart70569 Germany

ISBN: (纸本)9783031408632

Coupled systems of porous media and free flow can be modelled by the Stokes equations in the free-flow domain, Darcy’s law in the porous medium, and an appropriate set of coupling conditions on the fluid–porous interface. Discretisation of the coupled Stokes–Darcy problem leads to a large, sparse, ill-conditioned, and nonsymmetric linear system. We discretise the system using the MAC scheme, i.e., the finite volume method on staggered grids. To accelerate convergence of the GMRES method, efficient preconditioners are needed. We propose a block diagonal, a block triangular and a constraint preconditioner for the Stokes–Darcy problem with the classical set of coupling conditions based on the Beavers–Joseph condition and the generalised coupling conditions which were developed for arbitrary flow to the interface. We show the robustness and efficiency of the proposed preconditioners in numerical experiments. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Finite volume method

来源：评论

学校读者我要写书评

暂无评论

Biomechanical Surrogate Modelling Using Stabilized Vectorial Greedy Kernel Methods

Biomechanical Surrogate Modelling Using Stabilized Vectorial...

引用

European Conference on numerical Mathematics and Advanced Applications, ENUMATH 2019

作者： Haasdonk, Bernard Wenzel, Tizian Santin, Gabriele Schmitt, Syn Institute for Applied Analysis and Numerical Simulation University of Stuttgart Stuttgart Germany Center for Information and Communication Technology Fondazione Bruno Kessler Trento Italy Institute for Modelling and Simulation of Biomechanical Systems University of Stuttgart Stuttgart Germany

ISBN: (纸本)9783030558734

Greedy kernel approximation algorithms are successful techniques for sparse and accurate data-based modelling and function approximation. Based on a recent idea of stabilization (Wenzel et al., A novel class of stabilized greedy kernel approximation algorithms: convergence, stability & uniform point distribution. e-prints. arXiv:1911.04352, 2019) of such algorithms in the scalar output case, we here consider the vectorial extension built on VKOGA (Wirtz and Haasdonk, Dolomites Res Notes Approx 6:83–100, 2013. We introduce the so called γ-restricted VKOGA, comment on analytical properties and present numerical evaluation on data from a clinically relevant application, the modelling of the human spine. The experiments show that the new stabilized algorithms result in improved accuracy and stability over the non-stabilized algorithms. © 2021, Springer Nature Switzerland AG.

关键词： Approximation algorithms

来源：评论

学校读者我要写书评

暂无评论

Compressible multi-component flow in porous media with Maxwell-Stefan diffusion

arXiv

引用

arXiv 2019年

作者： Ostrowski, Lukas Rohde, Christian Institute of Applied Analysis and Numerical Simulation University of Stuttgart

We introduce a Darcy-scale model to describe compressible multi-component flow in a fully saturated porous medium. In order to capture cross-diffusive effects between the different species correctly, we make use of the Maxwell–Stefan theory in a thermodynamically consistent way. For inviscid flow the model turns out to be a nonlinear system of hyperbolic balance laws. We show that the dissipative structure of the Maxwell-Stefan operator permits to guarentee the existence of global classical solutions for initial data close to equilibria. Furthermore it is proven by relative entropy techniques that solutions of the Darcy-scale model tend in a certain long-time regime to solutions of a parabolic limit system.35L65, 76N10, 76S05 Copyright © 2019, The Authors. All rights reserved.

关键词： Entropy

来源：评论

学校读者我要写书评

暂无评论

Model reduction of parametrized evolution problems using the reduced basis method with adaptive time partitioning

Model reduction of parametrized evolution problems using the...

引用

5th International Conference on Adaptive Modeling and simulation, ADMOS 2011

作者： Dihlmann, Markus Drohmann, Martin Haasdonk, Bernard Institute of Applied Analysis and Numerical Simulation University of Stuttgart Pfaffenwaldring 57 70569 Stuttgart Germany Institute of Computational and Applied Mathematics University of Münster Einsteinstr. 62 48149 Münster Germany

ISBN: (纸本)9788493964030

Modern simulation scenarios require real-time or many query responses from a simulation model. This is the driving force for increased efforts in model order reduction for high dimensional dynamical systems or partial differential equations. This demand for fast simulation models is even more critical for parametrized problems. Several snapshot-based methods for basis construction exist for parametrized model order reduction, e.g. proper orthogonal decomposition (POD) or reduced basis (RB) methods. An often faced problem is that the produced reduced models for a given accuracy tolerance are still of too high dimension. This is especially the case for evolution problems where the model shows high variability during time evolution. We will present an approach to gain control over the online complexity of a reduced model by an adaptive time domain partitioning. Thereby we can prescribe simultaneously a desired error tolerance and a limiting size of the dimension of the reduced model. This leads to fast and accurate reduced models. The method will be applied to an advection problem.

关键词： Partial differential equations

来源：评论

学校读者我要写书评

暂无评论

Relativistic and electron-correlation effects in static dipole polarizabilities for main-group elements

引用

Physical Review A 2024年第4期110卷 042805页

作者： YingXing Cheng Numerical Mathematics for High Performance Computing Institute of Applied Analysis and Numerical Simulation University of Stuttgart Pfaffenwaldring 57 Stuttgart 70569 Germany

In this study, I compute the static dipole polarizability of main-group elements using the finite-field method combined with relativistic coupled-cluster and configuration-interaction simulations. The computational results closely align with the values recommended in the 2018 Table of static dipole polarizabilities of neutral elements [Mol. Phys. 117, 1200 (2019)]. Additionally, I investigate the influence of relativistic effects and electron correlation on atomic dipole polarizabilities. Specifically, three types of relativistic effects impacting dipole polarizabilities are studied: scalar-relativistic, spin-orbit coupling, and fully relativistic Dirac-Coulomb effects. The results indicate that scalar-relativistic effects are predominant for atoms in groups 1 and 2, with minimal influence from spin-orbit coupling effects. Conversely, for elements in groups 13–18, scalar-relativistic effects are less significant, while spin-orbit coupling significantly affects elements starting from the fourth row in groups 13 and 14 and from the fifth row in groups 15–18. In each category of relativistic effects, the impact of electron correlation is evaluated. The results show that electron correlation significantly influences dipole polarizability calculations, particularly for atoms from groups 1, 2, 13, and 14, but is less significant for atoms from groups 15–18. This study provides a comprehensive and consistent data set of dipole polarizabilities and contributes to a systematic understanding of the roles of relativistic and electron-correlation effects in atomic dipole polarizabilities, serving as a valuable reference for future research.

关键词： Electron correlation calculations for atoms & ions Electronic structure of atoms & molecules Relativistic & quantum electrodynamic effects in atoms, molecules,& ions Spin-orbit coupling

来源：评论

学校读者我要写书评

暂无评论

A-Posteriori Error Estimation for Parameterized Kernel-Based Systems

引用

IFAC Proceedings Volumes 2012年第2期45卷 763-768页

作者： Daniel Wirtz Bernard Haasdonk Institute for Applied Analysis and Numerical Simulation University of Stuttgart 70569 Stuttgart Pfaffenwaldegger 57 – Germany

Abstract This work is concerned with derivation of fully offline/online decomposable efficient a-posteriori error estimators for reduced parameterized nonlinear kernel-based systems. The dynamical systems under consideration consist of a nonlinear, time- and parameter-dependent kernel expansion representing the system's inner dynamics as well as time- and parameter-affine inputs, initial conditions and outputs. The estimators are established for a reduction technique originally proposed in Phillips et al. (2003) and are an extension of the estimators derived in Wirtz and Haasdonk (2012) to the fully time-dependent, parameterized setting. Key features for the efficient error estimation are to use local Lipschitz constants provided by a certain class of kernels and an iterative scheme to balance computation cost against estimation sharpness. Together with the affinely time/parameter-dependent system components a full offline/online decomposition for both the reduction process and the error estimators is possible. Some experimental results for synthetic systems illustrate the efficient evaluation of the derived error estimators for different parameters.

关键词： nonlinear parameterized dynamical systems model reduction kernel methods a-posteriori error estimates offline/online decomposition subspace projection

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：