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In this paper, we consider the adaptive Eulerian--Lagrangian method (ELM) for linear convection-diffusion problems. Unlike the classical a posteriori error estimations, we estimate the temporal error along the characteristics and derive a…

Numerical Analysis · Mathematics 2012-09-07 Xiaozhe Hu , Young-Ju Lee , Jinchao Xu , Chensong Zhang

In this paper, we develop a space-time upscaling framework that can be used for many challenging porous media applications without scale separation and high contrast. Our main focus is on nonlinear differential equations with multiscale…

Numerical Analysis · Mathematics 2019-09-04 Wing T. Leung , Eric T. Chung , Yalchin Efendiev , Maria Vasilyeva , Mary Wheeler

A upscaled lattice Boltzmann method (LBM) for flow simulations in heterogeneous porous media, at both pore and Darcy scales, is proposed in this paper. In the micro-scale simulations, we model flows using LBM with the modified Guo et al.…

Computational Physics · Physics 2013-12-03 Jun Li , Donald Brown

Thermal fluctuations play an increasingly important role in micromagnetic research relevant for various biomedical and other technological applications. Until now, it was deemed necessary to use a time stepping algorithm with a fixed time…

Mesoscale and Nanoscale Physics · Physics 2020-12-24 J. Leliaert , J. Mulkers , J. De Clercq , A. Coene , M. Dvornik , B. Van Waeyenberge

We are interested in numerically solving a transitional model derived from the Bloch model. The Bloch equation describes the time evolution of the density matrix of a quantum system forced by an electromagnetic wave. In a high frequency and…

Analysis of PDEs · Mathematics 2023-08-02 Brigitte Bidégaray-Fesquet , Clément Jourdana , Léopold Trémant

In this paper, we propose a rigorous and accurate non-local (in the oversampled region) upscaling framework based on some recently developed multiscale methods [10]. Our proposed method consists of identifying multi-continua parameters via…

Numerical Analysis · Mathematics 2018-08-01 Eric T. Chung , Yalchin Efendiev , Wing Tat Leung , Yating Wang , Maria Vasilyeva

The numerical approximation of an inverse problem subject to the convection--diffusion equation when diffusion dominates is studied. We derive Carleman estimates that are on a form suitable for use in numerical analysis and with explicit…

Numerical Analysis · Mathematics 2020-06-25 Erik Burman , Mihai Nechita , Lauri Oksanen

A formulation for thermal noise in the stochastic form of the Landau Lifshitz Bloch equation used for modeling the magnetization dynamics at elevated temperatures is presented. The diffusion coefficients for thermal fluctuations are…

Statistical Mechanics · Physics 2021-09-16 Marco Menarini , Vitaliy Lomakin

How heterogeneous multiscale methods (HMM) handle fluctuations acting on the slow variables in fast-slow systems is investigated. In particular, it is shown via analysis of central limit theorems (CLT) and large deviation principles (LDP)…

Probability · Mathematics 2016-01-12 David Kelly , Eric Vanden-Eijnden

The dynamic behaviour of periodic thermodiffusive multi-layered media excited by harmonic oscillations is studied. In the framework of linear thermodiffusive elasticity, periodic laminates, whose elementary cell is composed by an arbitrary…

Computational Engineering, Finance, and Science · Computer Science 2021-10-06 Francesca Fantoni , Lorenzo Morini , Andrea Bacigalupo , Marco Paggi

We propose and analyse a hybrid numerical-asymptotic $hp$ boundary element method for time-harmonic scattering of an incident plane wave by an arbitrary collinear array of sound-soft two-dimensional screens. Our method uses an approximation…

Numerical Analysis · Mathematics 2014-08-12 David P. Hewett , Stephen Langdon , Simon N. Chandler-Wilde

Dispersive and Strichartz estimates for solutions to general strictly hyperbolic partial differential equations with constant coefficients are considered. The global time decay estimates of $L^p-L^q$ norms of propagators are obtained, and…

Analysis of PDEs · Mathematics 2010-04-27 Michael Ruzhansky , James Smith

We proceed here with our systematic study, initiated in [3], of multiscale problems with defects, within the context of homogenization theory. The case under consideration here is that of a diffusion equation with a diffusion coefficient of…

Analysis of PDEs · Mathematics 2019-01-29 Xavier Blanc , Marc Josien , Claude Le Bris

Boundary integral methods are attractive for solving homogeneous linear constant coefficient elliptic partial differential equations on complex geometries, since they can offer accurate solutions with a computational cost that is linear or…

Numerical Analysis · Mathematics 2023-01-25 Fredrik Fryklund , Sara Pålsson , Anna-Karin Tornberg

The paper starts by giving a motivation for this research and justifying the considered stochastic diffusion models for cosmic microwave background radiation studies. Then it derives the exact solution in terms of a series expansion to a…

Applications · Statistics 2019-11-05 Phil Broadbridge , Alexander D. Kolesnik , Nikolai Leonenko , Andriy Olenko

Riemannian diffusion models draw inspiration from standard Euclidean space diffusion models to learn distributions on general manifolds. Unfortunately, the additional geometric complexity renders the diffusion transition term inexpressible…

Machine Learning · Computer Science 2023-11-01 Aaron Lou , Minkai Xu , Stefano Ermon

We propose a new randomized optimization method for high-dimensional problems which can be seen as a generalization of coordinate descent to random subspaces. We show that an adaptive sampling strategy for the random subspace significantly…

Optimization and Control · Mathematics 2019-12-19 Jonathan Lacotte , Mert Pilanci , Marco Pavone

This paper presents a homogenization framework for elastomeric metamaterials exhibiting long-range correlated fluctuation fields. Based on full-scale numerical simulations on a class of such materials, an ansatz is proposed that allows to…

Soft Condensed Matter · Physics 2018-10-29 O. Rokoš , M. M. Ameen , R. H. J. Peerlings , M. G. D. Geers

We consider deterministic and stochastic perturbations of dynamical systems with conservation laws in $\R^3$. The Landau-Lifshitz equation for the magnetization dynamics in ferromagnetics is a special case of our system. The averaging…

Probability · Mathematics 2012-08-31 Mark Freidlin , Wenqing Hu

Metasurfaces, consisting of large arrays of interacting subwavelength scatterers, pose significant challenges for general-purpose computational methods due to their large electric dimensions and multiscale nature. This paper introduces an…

Computational Physics · Physics 2024-10-07 Emanuele Corsaro , Giovanni Miano , Antonello Tamburrino , Salvatore Ventre , Carlo Forestiere