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Diffeomorphic matching (only one of several names for this technique) is a technique for non-rigid registration of curves and surfaces in which the curve or surface is embedded in the flow of a time-series of vector fields. One seeks the…

Numerical Analysis · Mathematics 2009-11-13 C. J. Cotter

The study of uncertainty propagation is of fundamental importance in plasma physics simulations. To this end, in the present work we propose a novel stochastic Galerkin (sG) particle {method} for collisional kinetic models of plasmas under…

Numerical Analysis · Mathematics 2023-03-22 Andrea Medaglia , Lorenzo Pareschi , Mattia Zanella

In this work, we derive particle schemes, based on micro-macro decomposition, for linear kinetic equations in the diffusion limit. Due to the particle approximation of the micro part, a splitting between the transport and the collision part…

Numerical Analysis · Mathematics 2017-01-19 Anaïs Crestetto , Nicolas Crouseilles , Mohammed Lemou

We consider the problem of sampling from a distribution governed by a potential function. This work proposes an explicit score based MCMC method that is deterministic, resulting in a deterministic evolution for particles rather than a…

Machine Learning · Statistics 2023-10-03 Hong Ye Tan , Stanley Osher , Wuchen Li

In this paper, we consider nonlinear diffusion processes driven by space-time white noises, which have an interpretation in terms of partial differential equations. For a specific choice of coefficients, they correspond to the Landau…

Probability · Mathematics 2007-05-23 Joaquin Fontbona , Helene Guerin , Sylvie Meleard

We consider a system of N classical particles, interacting via a smooth, short- range potential, in a weak-coupling regime. This means that N tends to infinity when the interaction is suitably rescaled. The j-particle marginals, which obey…

Mathematical Physics · Physics 2014-01-29 Alexander V. Bobylev , Mario Pulvirenti , Chiara Saffirio

We describe the remapped particle-mesh method, a new mass-conserving method for solving the density equation which is suitable for combining with semi-Lagrangian methods for compressible flow applied to numerical weather prediction. In…

Atmospheric and Oceanic Physics · Physics 2009-11-13 Colin J. Cotter , Jason Frank , Sebastian Reich

A variational method is used to derive a self-consistent macro-particle model for relativistic electromagnetic kinetic plasma simulations. Extending earlier work [E. G. Evstatiev and B. A. Shadwick, J. Comput. Phys., vol. 245, pp. 376-398,…

Computational Physics · Physics 2014-04-22 A. B. Stamm , B. A. Shadwick , E. G. Evstatiev

We consider the problem of statistical inference for a class of partially-observed diffusion processes, with discretely-observed data and finite-dimensional parameters. We construct unbiased estimators of the score function, i.e. the…

Methodology · Statistics 2021-05-12 Jeremy Heng , Jeremie Houssineau , Ajay Jasra

The reconstruction of smooth density fields from scattered data points is a procedure that has multiple applications in a variety of disciplines, including Lagrangian (particle-based) models of solute transport in fluids. In random walk…

Computational Physics · Physics 2019-09-04 Guillem Sole-Mari , Diogo Bolster , Daniel Fernàndez-Garcia , Xavier Sanchez-Vila

The purpose of this paper is to propose a time-step-robust cell-to-cell integration of particle trajectories in 3-D unstructured meshes in particle/mesh Lagrangian stochastic methods. The main idea is to dynamically update the mean fields…

Computation · Statistics 2023-04-19 Guilhem Balvet , Jean-Pierre Minier , Christophe Henry , Yelva Roustan , Martin Ferrand

We develop a framework for analyzing the momentum balance of laminar particle-laden flows based on immersed boundary methods, which solve the Navier-Stokes equations and resolve the particle surfaces. This framework differs from previous…

Fluid Dynamics · Physics 2018-06-04 E. Biegert , B. Vowinckel , E. Meiburg

An innovative field-particle correlation technique is proposed that uses single-point measurements of the electromagnetic fields and particle velocity distribution functions to investigate the net transfer of energy from fields to particles…

Space Physics · Physics 2016-08-17 Kristopher G Klein , Gregory G Howes

We present a simple modification of the direct-forcing immersed boundary method (IBM) proposed by Uhlmann [J. Comput. Phys, 2005] in order to enable it to be applied to particulate flows with solid-to-fluid density ratios around unity. The…

Fluid Dynamics · Physics 2023-06-21 Manuel Garcia-Villalba , Blanca Fuentes , Jan Dusek , Manuel Moriche , Markus Uhlmann

We describe an experimental technique to measure the chemical potential, $\mu$, in atomically thin layered materials with high sensitivity and in the static limit. We apply the technique to a high quality graphene monolayer to map out the…

Mesoscale and Nanoscale Physics · Physics 2021-04-21 Fangyuan Yang , Alexander A. Zibrov , Ruiheng Bai , Takashi Taniguchi , Kenji Watanabe , Michael P. Zaletel , Andrea F. Young

Score estimation is the backbone of score-based generative models (SGMs), especially denoising diffusion probabilistic models (DDPMs). A key result in this area shows that with accurate score estimates, SGMs can efficiently generate samples…

Machine Learning · Statistics 2025-04-08 Sinho Chewi , Alkis Kalavasis , Anay Mehrotra , Omar Montasser

In this paper, we present a finite difference heterogeneous multiscale method for the Landau-Lifshitz equation with a highly oscillatory diffusion coefficient. The approach combines a higher order discretization and artificial damping in…

Numerical Analysis · Mathematics 2021-08-24 Lena Leitenmaier , Olof Runborg

Landau damping is the mechanism of plasma and beam stabilization; it arises through energy transfer from collective modes to the incoherent motion of resonant particles. Normally this resonance requires the resonant particle's frequency to…

Accelerator Physics · Physics 2018-01-31 Alexandru Macridin , Alexey Burov , Eric Stern , James Amundson , Panagiotis Spentzouris

A novel numerical formulation for solving fluid-structure interaction (FSI) problems is proposed where the fluid field is spatially discretized using smoothed particle hydrodynamics (SPH) and the structural field using the finite element…

Computational Engineering, Finance, and Science · Computer Science 2021-06-16 Sebastian L. Fuchs , Christoph Meier , Wolfgang A. Wall , Christian J. Cyron

A novel smooth immersed boundary method (IBM) based on a direct-forcing formulation is proposed to simulate incompressible dense particle-laden flows. This IBM relies on a regularization of the transfer function between the Eulerian grid…

Computational Physics · Physics 2023-04-24 Victor Chéron , Fabien Evrard , Berend van Wachem