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In this paper we develop a framework for moment-based adaptive time integration of deterministic multifrequency thermal radiation transpot (TRT). We generalize our recent semi-implicit-explicit (IMEX) integration framework for gray TRT to…

Numerical Analysis · Mathematics 2026-02-11 Ben S. Southworth , Steven Walton , Steven B. Roberts , HyeongKae Park

The thermal radiative transfer (TRT) equations form an integro-differential system that describes the propagation and collisional interactions of photons. Computing accurate and efficient numerical solutions TRT are challenging for several…

Numerical Analysis · Mathematics 2021-11-09 Ryan G. McClarren , James A. Rossmanith , Minwoo Shin

We introduce the Weak-form Estimation of Nonlinear Dynamics (WENDy) method for estimating model parameters for non-linear systems of ODEs. Without relying on any numerical differential equation solvers, WENDy computes accurate estimates and…

Machine Learning · Computer Science 2023-11-27 David M. Bortz , Daniel A. Messenger , Vanja Dukic

We present a method that employs physics-informed deep learning techniques for parametrically solving partial differential equations. The focus is on the steady-state heat equations within heterogeneous solids exhibiting significant phase…

Machine Learning · Computer Science 2024-01-05 Shahed Rezaei , Ahmad Moeineddin , Michael Kaliske , Markus Apel

A new group of reduced-order models (ROMs) for nonlinear thermal radiative transfer (TRT) problems is presented. They are formulated by means of the nonlinear projective approach and data compression techniques. The nonlinear projection is…

Numerical Analysis · Mathematics 2024-03-12 Joseph M. Coale , Dmitriy Y. Anistratov

We outline a general approach to the computation of transport properties of interacting systems at low temperetures and frequencies. We show that if the fixed point and the irrelevant operators around it are known, then by studying the…

Strongly Correlated Electrons · Physics 2009-11-10 Natan Andrei , Efrat Shimshoni , Achim Rosch

Thermodynamics and transport properties of a dissipative particle in a tight-binding model are studied through specific heat and optical conductivity. A weak coupling theory is constituted to study the crossover behavior between the…

Statistical Mechanics · Physics 2009-10-30 Takeo Kato , Masatoshi Imada

The moment quantities associated with the nonlinear Schrodinger equation offer important insights towards the evolution dynamics of such dispersive wave partial differential equation (PDE) models. The effective dynamics of the moment…

Pattern Formation and Solitons · Physics 2024-06-10 Su Yang , Shaoxuan Chen , Wei Zhu , P. G. Kevrekidis

Quasiperiodic systems are an intermediate class of systems between periodic crystals and disordered systems, famously exhibiting metal-insulator transitions (MITs) even in one dimension. While their transport properties have been studied…

Disordered Systems and Neural Networks · Physics 2026-05-21 Raul Liquito , Miguel Gonçalves , Bruno Amorim , Eduardo V. Castro

We present a differentiable weak-form learning approach for accelerating finite element simulations. Rather than introducing black-box source terms in the strong form of the governing equations, we augment the momentum equation directly in…

Fluid Dynamics · Physics 2026-01-29 Junoh Jung , Emil Constantinescu

The Weak form Estimation of Nonlinear Dynamics (WENDy) method is a recently proposed class of parameter estimation algorithms that exhibits notable noise robustness and computational efficiency. This work examines the coverage and bias…

Methodology · Statistics 2025-10-07 Abhi Chawla , David M. Bortz , Vanja Dukic

The parametric greedy latent space dynamics identification (gLaSDI) framework has demonstrated promising potential for accurate and efficient modeling of high-dimensional nonlinear physical systems. However, it remains challenging to handle…

Computational Engineering, Finance, and Science · Computer Science 2025-06-11 Xiaolong He , April Tran , David M. Bortz , Youngsoo Choi

Colloidal quantum dots (QDs) and their thin-films are increasingly used in electronic and photonic devices replacing traditional bulk semiconductors. However, thermal properties of the QDs are comparatively underexplored relative to device…

We introduce the idea of weakly coherent collisional models, where the elements of an environment interacting with a system of interest are prepared in states that are approximately thermal, but have an amount of coherence proportional to a…

In the context of population dynamics, identifying effective model features, such as fecundity and mortality rates, is generally a complex and computationally intensive process, especially when the dynamics are heterogeneous across the…

Populations and Evolution · Quantitative Biology 2025-07-01 Rainey Lyons , Vanja Dukic , David M. Bortz

A simplified transient energy-transport system for semiconductors subject to mixed Dirichlet-Neumann boundary conditions is analyzed. The model is formally derived from the non-isothermal hydrodynamic equations in a particular vanishing…

Analysis of PDEs · Mathematics 2012-06-26 Ansgar Jüngel , René Pinnau , Elisa Röhrig

The sparse identification of nonlinear dynamics (SINDy) has been established as an effective method to learn interpretable models of dynamical systems from data. However, for high-dimensional slow-fast dynamical systems, the regression…

Dynamical Systems · Mathematics 2025-07-02 Diemen Delgado-Cano , Erick Kracht , Urban Fasel , Benjamin Herrmann

In this work, we define a practical identifiability criterion, (e, q)-identifiability, based on a parameter e, reflecting the noise in observed variables, and a parameter q, reflecting the mean-square error of the parameter estimator. This…

Methodology · Statistics 2026-03-13 Nora Heitzman-Breen , Vanja Dukic , David M. Bortz

The method of moments is widely used for the reduction of kinetic equations into fluid models. It consists in extracting the moments of the kinetic equation with respect to a velocity variable, but the resulting system is a priori…

Computational Physics · Physics 2023-04-05 Michael R. A. Abdelmalik , Zhenning Cai , Teddy Pichard

We introduce a machine learning framework for moment-equation modeling of rarefied gas flows, addressing strongly non-equilibrium conditions inaccessible to conventional computational fluid dynamics. Our approach utilizes high-order moments…

Fluid Dynamics · Physics 2025-11-04 Hang Song , Satyvir Singh , Manuel Torrilhon , Semih Cayci