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One classical canon of statistics is that large models are prone to overfitting, and model selection procedures are necessary for high dimensional data. However, many overparameterized models, such as neural networks, perform very well in…

Machine Learning · Statistics 2021-01-05 Xi Chen , Qiang Liu , Xin T. Tong

Diffusion models are able to generate photorealistic images in arbitrary scenes. However, when applying diffusion models to image translation, there exists a trade-off between maintaining spatial structure and high-quality content. Besides,…

Computer Vision and Pattern Recognition · Computer Science 2023-02-07 Shiqi Sun , Shancheng Fang , Qian He , Wei Liu

Discrete diffusion has become a leading framework for generative modeling in various applications including language, vision, and biology. Existing convergence theory, however, exhibits fundamental limitations. KL-based analyses diverge…

Machine Learning · Computer Science 2026-05-19 Kelvin Kan , Xingjian Li , Benjamin J. Zhang , Tuhin Sahai , Stanley Osher , Markos A. Katsoulakis

We aim at understanding transport in porous materials including regions with both high and low diffusivities. For such scenarios, the transport becomes structured (here: {\em micro-macro}). The geometry we have in mind includes regions of…

Mathematical Physics · Physics 2010-03-23 T. van Noorden , A. Muntean

In this work I show how a diffusion-advection equation in three space-dimensions may have its advection term weakly limited to a velocity field localized to a moving curve. This is rigorously accomplished through the technique of…

Analysis of PDEs · Mathematics 2021-06-24 Colin Klaus

In this work we develop a theory of Vessels. This object arises in the study of overdetermined 2D systems invariant in one of the variables, which are usually called time invariant. To each overdetermined time invariant 2D systems there is…

Functional Analysis · Mathematics 2008-12-22 Andrey Melnikov , Victor Vinnikov

We concern with the global existence and large time behavior of compressible fluids (including the inviscid gases, viscid gases, and Boltzmann gases) in an infinitely expanding ball. Such a problem is one of the interesting models in…

Analysis of PDEs · Mathematics 2018-09-26 Gang Xu , Huicheng Yin

We consider the initial-boundary value problem for the incompressible two-dimensional micropolar fluid model with angular viscosity in the upper half-plane. This model describes the motion of viscous fluids with microstructure. The global…

Analysis of PDEs · Mathematics 2025-08-27 Yinghui Wang , Weihao Zhang

We describe traveling waves in a basic model for three-dimensional water-wave dynamics in the weakly nonlinear long-wave regime. Small solutions that are periodic in the direction of translation (or orthogonal to it) form an…

Pattern Formation and Solitons · Physics 2015-06-26 Robert L. Pego , Jose Raul Quintero

Ion transport in biological tissues is crucial in the study of many biological and pathological problems. Some multi-cellular structures, like smooth muscles on the vessel walls, could be treated as periodic bi-domain structures, which…

Analysis of PDEs · Mathematics 2021-03-11 Chun Xiao , Xingye Yue , Huaxiong Huang , Shixin Xu

A fluid, with broken time-reversal symmetry, would exhibit odd transport coefficients, such as odd viscosity, thermal conductivity and diffusion coefficient, which may fundamentally alter the fluid properties and significantly influence the…

Soft Condensed Matter · Physics 2026-05-07 Yuxing Jiao , Mingcheng Yang

This article introduces a representation of dynamic meshes, adapted to some numerical simulations that require controlling the volume of objects with free boundaries, such as incompressible fluid simulation, some astrophysical simulations…

Fluid Dynamics · Physics 2022-01-26 Bruno Lévy

We study network properties of networks evolving in time based on optimal transport principles. These evolve from a structure covering uniformly a continuous space towards an optimal design in terms of optimal transport theory. At…

Physics and Society · Physics 2023-10-25 Diego Baptista , Caterina De Bacco

It is shown: 1) that in two-dimensional, incompressible, viscous flows the vorticity-area distribution evolves according to an advection-diffusion equation with a negative, time dependent diffusion coefficient and 2) how to use the…

chao-dyn · Physics 2009-10-31 H. W. Capel , R. A. Pasmanter

Obtaining system parameters and reconstructing the full flow state from limited velocity observations using conventional fluid dynamics solvers can be prohibitively expensive. Here we employ machine learning algorithms to overcome the…

Fluid Dynamics · Physics 2024-10-17 Vladimir Parfenyev , Mark Blumenau , Ilia Nikitin

We consider a class of convex optimization problems modelling temporal mass transport and mass change between two given mass distributions (the so-called dynamic formulation of unbalanced transport), where we focus on those models for which…

Optimization and Control · Mathematics 2018-03-13 Bernhard Schmitzer , Benedikt Wirth

The Boltzmann equation for d-dimensional inelastic Maxwell models is considered to analyze transport properties in spatially inhomogeneous states close to the simple shear flow. A normal solution is obtained via a Chapman--Enskog--like…

Statistical Mechanics · Physics 2009-11-13 Vicente Garzo

The diffusion model has shown success in generating high-quality and diverse solutions to trajectory optimization problems. However, diffusion models with neural networks inevitably make prediction errors, which leads to constraint…

Machine Learning · Computer Science 2024-06-04 Anjian Li , Zihan Ding , Adji Bousso Dieng , Ryne Beeson

Transport networks are crucial for the functioning of natural and technological systems. We study a mathematical model of vascular network adaptation, where the network structure dynamically adjusts to changes in blood flow and pressure.…

Adaptation and Self-Organizing Systems · Physics 2023-06-01 Konstantin Klemm , Erik Andreas Martens

We develop robust and scalable fully implicit nonlinear finite element solvers for the simulations of biological transportation networks driven by the gradient flow minimization of a non-convex energy cost functional. Our approach employs a…

Computational Engineering, Finance, and Science · Computer Science 2025-04-08 Jan Haskovec , Peter Markowich , Simone Portaro , Stefano Zampini