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Multi-species BGK models describe the dynamics of rarefied gases with constituent particles of different elements or compounds with potentially non-trivial velocity distributions. In this paper, moment equations for the bulk velocities,…

Mathematical Physics · Physics 2023-10-20 Evan Habbershaw , Ryan S. Glasby , Jeffrey R. Haack , Cory D. Hauck , Steven M. Wise

Theory and methods to obtain parametric reduced-order models by moment matching are presented. The definition of the parametric moment is introduced, and methods (model-based and data-driven) for the approximation of the parametric moment…

Systems and Control · Electrical Eng. & Systems 2025-06-13 Hanqing Zhang , Junyu Mao , Mohammad Fahim Shakib , Giordano Scarciotti

Convection-diffusion equations provide the basis for describing heat and mass transfer phenomena as well as processes of continuum mechanics. To handle flows in porous media, the fundamental issue is to model correctly the convective…

Numerical Analysis · Computer Science 2012-08-29 A. Churbanov , P. Vabishchevich

In Moln\'ar et al. [Phys. Rev. D 93, 114025 (2016)] the equations of anisotropic dissipative fluid dynamics were obtained from the moments of the Boltzmann equation based on an expansion around an arbitrary anisotropic single-particle…

Nuclear Theory · Physics 2016-12-07 Etele Molnár , Harri Niemi , Dirk H. Rischke

In this paper we propose and analyse a new formulation and pointwise divergence-free mixed finite element methods for the numerical approximation of Darcy--Brinkman equations in vorticity--velocity--pressure form, coupled with a transport…

Numerical Analysis · Mathematics 2024-07-04 Russel Demos , Rashmi Dubey , Ricardo Ruiz-Baier , Segundo Villa-Fuentes

Moment dynamics in stochastic chemical kinetics often involve an infinite chain of coupled equations, where lower-order moments depend on higher-order ones, making them analytically intractable. Moment bounding via semidefinite programming…

Optimization and Control · Mathematics 2026-04-07 Tomoki Sadatoshi , Antonis Papachristodoulou , Yutaka Hori

The Chemical Master Equation (CME) is used to stochastically model biochemical reaction networks, under the Markovian assumption. The low-order statistical moments induced by the CME are often the key quantities that one is interested in.…

Systems and Control · Computer Science 2017-07-04 Mohammad Naghnaeian , Domitilla Del Vecchio

In this paper, the pressure correctionfinite element method is proposed for the 2D/3D time-dependent thermomicropolarfluid equations. Thefirst-order and second-order backward difference formulas (BDF) are adopted to approximate the time…

Numerical Analysis · Mathematics 2022-03-30 Yuhang Ren , Demin Liu

Here we introduce new coarse-grained variables for a turbulent flow in the form of moments of its Reynolds-averaged Boltzmann equation. With the exception of the collision moments, the transport equations for the new variables are identical…

Fluid Dynamics · Physics 2015-04-21 Rafail V. Abramov

A finite-element method dependant adjoint-based procedure to determine the temperature field of structures based on measured displacements or strains and a set of standard loads is developed and tested. Given a series of force and…

In this work we present a structure preserving discretization for turbidity currents based on a mass-, energy-, enstrophy-, and vorticity-conserving formulation for 2D incompressible flows. This discretization exploits a dual-field…

Numerical Analysis · Mathematics 2020-12-15 Gonzalo G. de Diego , Artur Palha , Marc Gerritsma

We study the mathematical character of the angular moment equations of radiative transfer in spherical symmetry and conclude that the system is hyperbolic for general forms of the closure relation found in the literature. Hyperbolicity and…

Astrophysics · Physics 2009-10-31 Jose A. Pons , J. Ma. Ibanez , Juan A. Miralles

A recent paper by Cordero-Erausquin and Klartag provides a characterization of the measures $\mu$ on $\R^d$ which can be expressed as the moment measures of suitable convex functions $u$, i.e. are of the form $(\nabla u)\_\\#e^{- u}$ for…

Functional Analysis · Mathematics 2015-07-16 Filippo Santambrogio

Particle distributions in weakly collisional environments such as the magnetosphere have been observed to show deviations from the Maxwellian distribution. These can often be reproduced in kinetic simulations, but fluid models, which are…

Space Physics · Physics 2018-08-24 Jonathan Ng , Ammar Hakim , Amitava Bhattacharjee

We propose MomentsNeRF, a novel framework for one- and few-shot neural rendering that predicts a neural representation of a 3D scene using Orthogonal Moments. Our architecture offers a new transfer learning method to train on multi-scenes…

Computer Vision and Pattern Recognition · Computer Science 2024-07-04 Ahmad AlMughrabi , Ricardo Marques , Petia Radeva

Different relativistic quantum mechanics approaches have recently been used to calculate properties of various systems, form factors in particular. It is known that predictions, which most often rely on a single-particle current…

Nuclear Theory · Physics 2008-11-26 Bertrand Desplanques , Yu Bing Dong

Extreme events play a crucial role in fluid turbulence. Inspired by methods from field theory, these extreme events, their evolution and probability can be computed with help of the instanton formalism as minimizers of a suitable action…

Fluid Dynamics · Physics 2015-10-28 Tobias Grafke , Rainer Grauer , Stephan Schindel

This paper explores some applications of a two-moment inequality for the integral of the $r$-th power of a function, where $0 < r< 1$. The first contribution is an upper bound on the R\'{e}nyi entropy of a random vector in terms of the two…

Information Theory · Computer Science 2017-02-24 Galen Reeves

The numerical solution of time-dependent radiative transfer problems is challenging, both, due to the high dimension as well as the anisotropic structure of the underlying integro-partial differential equation. In this paper we propose a…

Numerical Analysis · Mathematics 2015-12-04 Herbert Egger , Matthias Schlottbom

We consider radiation transport theory applied to non-dispersive but refractive media. This setting is used to discuss Minkowski's and Abraham's electromagnetic momentum, and to derive conservation equations independent of the choice of…

Astrophysics · Physics 2009-11-10 Mattias Marklund