本文提出一种基于字典的在线自适应保结构 MOR 方法,通过状态、非线性项和 DEIM 点字典实现与全维无关的局部基调整,并在波动方程和 Sine-Gordon 模型上验证其效率。
摘要:
针对参数化问题的经典模型降阶(MOR)可能因所需投影基的规模过大而导致计算效率低下,尤其是对于 Kolmogorov n-width 衰减缓慢的问题。此外,动力系统可能具有哈密顿结构,并且在降阶过程中应予以保持。在本报告中,我们通过提出一种相应的基于字典的在线自适应 MOR 方法来解决这两个方面的问题。该方法需要状态变量、非线性项以及离散经验插值(DEIM)点的字典。在在线仿真过程中,以在线高效的方式执行局部基扩展/简化,即基修改和降阶模型在线仿真的运行时复杂度不依赖于完整状态维度。在线性波动方程和非线性 Sine-Gordon 算例上的实验证明了该方法的高效性。
英文摘要:
Classical model order reduction (MOR) for parametric problems may become computationally inefficient due to large sizes of the required projection bases, especially for problems with slowly decaying Kolmogorov n-widths. Additionally, Hamiltonian structure of dynamical systems may be available and should be preserved during the reduction. In the current presentation, we address these two aspects by proposing a corresponding dictionary-based, online-adaptive MOR approach. The method requires dictionaries for the state-variable, non-linearities and discrete empirical interpolation (DEIM) points. During the online simulation, local basis extensions/simplifications are performed in an online-efficient way, i.e. the runtime complexity of basis modifications and online simulation of the reduced models do not depend on the full state dimension. Experiments on a linear wave equation and a non-linear Sine-Gordon example demonstrate the efficiency of the approach.
A convexity-preserving and perimeter-decreasing parametric finite element method for the area-preserving curve shortening flow
提出并分析了一种求解保面积曲线缩短流的半离散参数有限元格式。该方案基于Dziuk的方法(SIAM J. Numer. Anal. 36(6):1808-1830,1999)。我们证明了该方案保持了两个基本的几何结构的流与一个初始凸曲线:(i)保凸性,(ii)周长减少的性质。据我们所知,第一次严格证明了近似流的数值格式的保凸性。此外,建立了半离散格式的误差估计,数值结果证明了格式的保结构性和精度。
A Structure-Preserving Graph Neural Solver for Parametric Hyperbolic Conservation Laws
School of Artificial Intelligence;Suzhou Institute for Advanced Research, University of Science;Suzhou Big Data \& AI Research;Engineering Center, China;School of Mathematical Sciences, University of Science;School of Mathematical Sciences
A parametric finite element method for a degenerate multi-phase Stefan problem with triple junctions
Université Claude Bernard Lyon 1, CNRS, Centrale Lyon, INSA Lyon, Université Jean Monnet, ICJ UMR5208(里昂第一大学、法国国家科学研究中心、中央里昂理工学院、里昂国立应用科学学院、让·莫内大学、ICJ联合研究实验室);Fakultät für Mathematik, Universität Regensburg(雷根斯堡大学数学学院);Dipartimento di Mathematica, Università di Trento(特伦托大学数学系)