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A new framework is introduced for constructing interpretable and truly reliable reduced models for multiscale problems in situations without scale separation. Hydrodynamic approximation to the kinetic equation is used as an example to…

Computational Physics · Physics 2019-10-31 Jiequn Han , Chao Ma , Zheng Ma , Weinan E

This paper presents a comprehensive review of the wave-function approach for derivation of the number-resolved Master equations, used for description of transport and measurement in mesoscopic systems. The review contains important…

Mesoscale and Nanoscale Physics · Physics 2017-06-20 Shmuel Gurvitz

We address the question of parameterizing the subgrid scales in simulations of geophysical flows by applying stochastic mode reduction to the one-dimensional stochastically forced shallow water equations. The problem is formulated in…

Fluid Dynamics · Physics 2018-08-17 Matthias Zacharuk , Stamen I. Dolaptchiev , Ulrich Achatz , Ilya Timofeyev

Atmospheric models used for weather and climate prediction are traditionally formulated in a deterministic manner. In other words, given a particular state of the resolved scale variables, the most likely forcing from the sub-grid scale…

Machine Learning · Computer Science 2024-02-16 Hannah M. Christensen , Salah Kouhen , Greta Miller , Raghul Parthipan

Given the growth in the variety and precision of astronomical datasets of interest for cosmology, the best cosmological constraints are invariably obtained by combining data from different experiments. At the likelihood level, one…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-04 Arrykrishna Mootoovaloo , Carlos García-García , David Alonso , Jaime Ruiz-Zapatero

In a previous paper [Adcock & Huybrechs, 2019] we described the numerical approximation of functions using redundant sets and frames. Redundancy in the function representation offers enormous flexibility compared to using a basis, but…

Numerical Analysis · Mathematics 2020-07-13 Ben Adcock , Daan Huybrechs

In this paper, we present a unified analysis of matrix completion under general low-dimensional structural constraints induced by {\em any} norm regularization. We consider two estimators for the general problem of structured matrix…

Machine Learning · Statistics 2018-11-26 Suriya Gunasekar , Arindam Banerjee , Joydeep Ghosh

The estimation of parameters from data is a common problem in many areas of the physical sciences, and frequently used algorithms rely on sets of simulated data which are fit to data. In this article, an analytic solution for…

Data Analysis, Statistics and Probability · Physics 2022-09-27 Daniel Britzger

The methods for studying the epoch of cosmic reionization vary from full radiative transfer simulations to purely analytical models. While numerical approaches are computationally expensive and are not suitable for generating many mock…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-15 Alexander A. Kaurov

The linearized Boltzmann equation is considered to describe small spatial perturbations of the homogeneous cooling state. The corresponding macroscopic balance equations for the density, temperature, and flow velocity are derived from it as…

Statistical Mechanics · Physics 2015-06-24 J. Javier Brey , James W. Dufty , M. J. Ruiz-Montero

In this work we propose reduced order methods as a reliable strategy to efficiently solve parametrized optimal control problems governed by shallow waters equations in a solution tracking setting. The physical parametrized model we deal…

Numerical Analysis · Mathematics 2023-08-08 Maria Strazzullo , Francesco Ballarin , Gianluigi Rozza

Simulation schemes that allow to change molecular representation in a subvolume of the simulation box while preserving the equilibrium with the surrounding introduce conceptual problems of thermodynamic consistency. In this work we present…

Statistical Mechanics · Physics 2010-03-31 Simon Poblete , Matej Praprotnik , Kurt Kremer , Luigi Delle Site

Due to the computational complexity of micro-swimmer models with fully resolved hydrodynamics, parameter estimation has been prohibitively expensive. Here, we describe a Bayesian uncertainty quantification framework that is highly…

Quantitative Methods · Quantitative Biology 2019-10-29 Karen Larson , Sarah Olson , Anastasios Matzavinos

Complex systems with many degrees of freedom are typically intractable, but some of their behaviors may admit simpler effective descriptions. The question of when such effective descriptions are possible remains open. The paradigmatic…

Statistical Mechanics · Physics 2020-11-26 Charlotte Strandkvist , Pavel Chvykov , Mikhail Tikhonov

The representation of nonlinear sub-grid processes, especially clouds, has been a major source of uncertainty in climate models for decades. Cloud-resolving models better represent many of these processes and can now be run globally but…

Atmospheric and Oceanic Physics · Physics 2022-06-08 Stephan Rasp , Michael S. Pritchard , Pierre Gentine

A new framework is proposed for the evaluation of stochastic subgrid-scale parameterizations in the context of MAOOAM, a coupled ocean-atmosphere model of intermediate complexity. Two physically-based parameterizations are investigated, the…

Atmospheric and Oceanic Physics · Physics 2018-09-26 Jonathan Demaeyer , Stéphane Vannitsem

In this work we consider a mathematical model of the water treatment process and determine the effective characteristics of this model. At the microscopic length scale we describe our model in terms of a lattice random walk in a…

Mathematical Physics · Physics 2022-04-27 A. Piatnitski , A. Shamaev , E. Zhizhina

Projecting climate change is a generalization problem: we extrapolate the recent past using physical models across past, present, and future climates. Current climate models require representations of processes that occur at scales smaller…

The minimalist approach in the study of perturbations in fluid dynamics and magnetohydrodynamics involves describing their evolution in the linear regime using a single first-order ordinary differential equation, dubbed principal equation.…

Fluid Dynamics · Physics 2025-02-18 Nektarios Vlahakis

Tidally locked terrestrial planets around low-mass stars are the prime targets of finding potentially habitable exoplanets. Several atmospheric general circulation models have been employed to simulate their possible climates, however,…

Earth and Planetary Astrophysics · Physics 2020-08-12 Mengyu Wei , Yixiao Zhang , Jun Yang