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We consider the problem of Active Source Identification (ASI) in steady-state Advection-Diffusion (AD) transport systems. Unlike existing bio-inspired heuristic methods, we propose a model-based method that employs the AD-PDE to capture the…

Robotics · Computer Science 2019-02-18 Reza Khodayi-mehr , Wilkins Aquino , Michael M. Zavlanos

Self-similar solutions of the coherent diffusion equation are derived and measured. The set of real similarity solutions is generalized by the introduction of a nonuniform phase surface, based on the elegant Gaussian modes of optical…

Quantum Physics · Physics 2015-05-19 O. Firstenberg , P. London , D. Yankelev , R. Pugatch , M. Shuker , N. Davidson

Diffusion models are a class of probabilistic generative models that have been widely used as a prior for image processing tasks like text conditional generation and inpainting. We demonstrate that these models can be adapted to make…

Machine Learning · Computer Science 2023-06-14 Marc Finzi , Anudhyan Boral , Andrew Gordon Wilson , Fei Sha , Leonardo Zepeda-Núñez

Modeling complex spatiotemporal dynamical systems, such as the reaction-diffusion processes, have largely relied on partial differential equations (PDEs). However, due to insufficient prior knowledge on some under-explored dynamical…

Machine Learning · Computer Science 2023-05-23 Chengping Rao , Pu Ren , Qi Wang , Oral Buyukozturk , Hao Sun , Yang Liu

Fractional diffusion has become a fundamental tool for the modeling of multiscale and heterogeneous phenomena. However, due to its nonlocal nature, its accurate numerical approximation is delicate. We survey our research program on the…

Numerical Analysis · Mathematics 2015-08-19 Ricardo H. Nochetto , Enrique Otarola , Abner J. Salgado

The release of a gas limited by surface desorption, or by diffusion from the bulk of spherical pebbles is revisited. A method is proposed to identify the release limiting process, by comparing a partial temperature ramp, up to slightly…

Other Condensed Matter · Physics 2009-11-13 Ricardo E. Avila

In the present work, we investigate the potential of fractional derivatives to model atmospheric dispersion of pollutants. We propose simple fractional differential equation models for the steady state spatial distribution of concentration…

Atmospheric and Oceanic Physics · Physics 2017-02-22 A. G. O. Goulart , M. J. Lazo , J. M. S. Suarez , D. M. Moreira

The well-posedness of a non-local advection-selection-mutation problem deriving from adaptive dynamics models is shown for a wide family of initial data. A particle method is then developed, in order to approximate the solution of such…

Numerical Analysis · Mathematics 2023-04-28 Frank Ernesto Alvarez , Jules Guilberteau

Physics-informed methods have gained a great success in analyzing data with partial differential equation (PDE) constraints, which are ubiquitous when modeling dynamical systems. Different from the common penalty-based approach, this work…

Methodology · Statistics 2024-10-08 Tongyu Li , Fang Yao

In many real-world settings, agents must learn from an offline dataset gathered by some prior behavior policy. Such a setting naturally leads to distribution shift between the behavior policy and the target policy being trained - requiring…

Machine Learning · Computer Science 2024-04-10 Matthew Thomas Jackson , Michael Tryfan Matthews , Cong Lu , Benjamin Ellis , Shimon Whiteson , Jakob Foerster

In this paper, a thermal-dynamical consistent model for mass transfer across permeable moving interfaces is proposed by using the energy variation method. We consider a restricted diffusion problem where the flux across the interface…

Numerical Analysis · Mathematics 2022-06-15 Yuzhe Qin , Huaxiong Huang , Yi Zhu , Chun Liu , Shixin Xu

This paper considers particle propagation in a cylindrical molecular communication channel, e.g. a simplified model of a blood vessel. Emitted particles are influenced by diffusion, flow, and a vertical force induced e.g. by gravity or…

Computational Physics · Physics 2019-02-26 Maximilian Schäfer , Wayan Wicke , Rudolf Rabenstein , Robert Schober

In recent years, research and development in nanoscale science and technology have grown significantly, with electrical transport playing a key role. A natural challenge for its description is to shed light on anomalous behaviours observed…

Populations and Evolution · Quantitative Biology 2025-04-10 Sara Bernardi , Paolo Begnamino , Marco Pizzi , Lamberto Rondoni

Predicting counterfactual distributions in complex dynamical systems is essential for scientific modeling and decision-making in domains such as public health and medicine. However, existing methods often rely on point estimates or purely…

Machine Learning · Computer Science 2025-09-15 Wenhao Mu , Zhi Cao , Mehmed Uludag , Alexander Rodríguez

We extend the energetic variational approach so it can be applied to a chemical reaction system with general mass action kinetics. Our approach starts with an energy-dissipation law. We show that the chemical equilibrium is determined by…

Chemical Physics · Physics 2021-01-04 Yiwei Wang , Chun Liu , Pei Liu , Bob Eisenberg

We propose a general framework for conditional sampling in PDE-based inverse problems, targeting the recovery of whole solutions from extremely sparse or noisy measurements. This is accomplished by a function-space diffusion model and…

Machine Learning · Computer Science 2026-02-06 Jiachen Yao , Abbas Mammadov , Julius Berner , Gavin Kerrigan , Jong Chul Ye , Kamyar Azizzadenesheli , Anima Anandkumar

In this paper, we show that unbalanced optimal transport provides a convenient framework to handle reaction and diffusion processes in a unified metric framework. We use a constructive method, alternating minimizing movements for the…

Analysis of PDEs · Mathematics 2017-04-18 Thomas Gallouët , Maxime Laborde , Léonard Monsaingeon

Fractional kinetic equations employ non-integer calculus to model anomalous relaxation and diffusion in many systems. While this approach is well explored, it so far failed to describe an important class of transport in disordered systems.…

Statistical Mechanics · Physics 2021-01-04 Wanli Wang , Eli Barkai

The diffusion of a bulk absorbed gas species out of spherical pebbles is studied analytically, stressing the usefulness of the time integral of the diffusion coefficient for analysis of arbitrary temperature schedule experiments. Highly…

Materials Science · Physics 2009-11-13 Ricardo E. Avila

In this paper, we present a novel numerical framework for solving a specific biological reaction-diffusion-advection system of cancer growth in three dimensions (3D) using particles of variable mass. We adopt empirical particle measures to…

Numerical Analysis · Mathematics 2026-05-20 Jingyuan Hu , Zhongjian Wang , Jack Xin , Zhiwen Zhang