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In a broad and fundamental type of ''inverse problems'' in science, one infers a spatially distributed physical attribute based on observations of processes that are controlled by the spatial attribute in question. The data-generating field…

Methodology · Statistics 2014-09-09 Zepu Zhang

Using mean-field theory, we compute the evolution of the magnetic field in a cylinder with outer perfectly conducting boundaries, an imposed axial magnetic and electric field. The thus injected magnetic helicity in the system can be…

Plasma Physics · Physics 2012-03-27 Koen Kemel , Axel Brandenburg , Hantao Ji

This paper introduces a Bayesian framework that combines Markov chain Monte Carlo (MCMC) sampling, dimensionality reduction, and neural density estimation to efficiently handle inverse problems that (i) must be solved multiple times, and…

Computational Engineering, Finance, and Science · Computer Science 2026-02-24 Giacomo Bottacini , Matteo Torzoni , Andrea Manzoni

We generalize the factorization method for inverse medium scattering using a particular factorization of the difference of two far field operators. Whilst the factorization method been used so far mainly to identify the shape of a…

Analysis of PDEs · Mathematics 2016-08-05 Evgeny Lakshtanov , Armin Lechleiter

The determination of Parton Distribution Functions from a finite set of data is a typical example of an inverse problem. Inverse problems are notoriously difficult to solve, in particular when a robust determination of the uncertainty in…

High Energy Physics - Lattice · Physics 2023-03-01 Alessandro Candido , Luigi Del Debbio , Tommaso Giani , Giacomo Petrillo

We consider boundary measurements for the wave equation on a bounded domain $M \subset \R^2$ or on a compact Riemannian surface, and introduce a method to locate a discontinuity in the wave speed. Assuming that the wave speed consist of an…

Analysis of PDEs · Mathematics 2011-06-17 Lauri Oksanen

We study image inverse problems with a normalizing flow prior. Our formulation views the solution as the maximum a posteriori estimate of the image conditioned on the measurements. This formulation allows us to use noise models with…

Machine Learning · Computer Science 2021-07-02 Jay Whang , Qi Lei , Alexandros G. Dimakis

A stochastic inverse heat transfer problem is formulated to infer the transient heat flux, treated as an unknown Neumann boundary condition. Therefore, an Ensemble-based Simultaneous Input and State Filtering as a Data Assimilation…

Numerical Analysis · Mathematics 2024-03-01 Kabir Bakhshaei , Umberto Emil Morelli , Giovanni Stabile , Gianluigi Rozza

Stochastic process models for spatiotemporal data underlying random fields find substantial utility in a range of scientific disciplines. Subsequent to predictive inference on the values of the random field (or spatial surface indexed…

Methodology · Statistics 2024-07-26 Aritra Halder , Didong Li , Sudipto Banerjee

One of the major challenges in the Bayesian solution of inverse problems governed by partial differential equations (PDEs) is the computational cost of repeatedly evaluating numerical PDE models, as required by Markov chain Monte Carlo…

Computation · Statistics 2016-05-03 Tiangang Cui , Youssef M. Marzouk , Karen E. Willcox

Estimating the magnetic field strength in the solar corona is crucial for understanding different physical processes happening over diverse spatio-temporal scales. However, the high temperatures and low density of the solar corona make this…

Solar and Stellar Astrophysics · Physics 2024-03-07 Upasna Baweja , Vaibhav Pant , Iñigo Arregui

[abridged] Inversion techniques are the most powerful methods to obtain information about the thermodynamical and magnetic properties of solar and stellar atmospheres. In the last years, we have witnessed the development of highly…

Astrophysics · Physics 2009-11-13 A. Asensio Ramos , M. J. Martinez Gonzalez , J. A. Rubino-Martin

A well known identifiability issue in factor analytic models is the invariance with respect to orthogonal transformations. This problem burdens the inference under a Bayesian setup, where Markov chain Monte Carlo (MCMC) methods are used to…

Methodology · Statistics 2022-03-17 Panagiotis Papastamoulis , Ioannis Ntzoufras

This paper addresses the problem of axisymetric rotating flows bounded by a fixed horizontal plate and subject to a permanent, uniform, vertical magnetic field (the so-called B\"odewadt-Hartmann problem). The aim is to find out which one of…

Fluid Dynamics · Physics 2020-06-11 Peter A. Davidson , Alban Pothérat

In this work, we are interested in the determination of the shape of the scatterer for the two dimensional time harmonic inverse medium scattering problems in acoustics. The scatterer is assumed to be a piecewise constant function with a…

Numerical Analysis · Mathematics 2021-01-12 J. Huang , Z. Deng , L. Xu

We report on an analytical and numerical study of the dynamics of a three-dimensional array of identical magnetic flux tubes in the reduced-magnetohydrodynamic description of the plasma. We propose that the long-time evolution of this…

High Energy Astrophysical Phenomena · Physics 2020-07-15 Muni Zhou , Nuno F. Loureiro , Dmitri A. Uzdensky

In inverse problems, we often have access to data consisting of paired samples $(x,y)\sim p_{X,Y}(x,y)$ where $y$ are partial observations of a physical system, and $x$ represents the unknowns of the problem. Under these circumstances, we…

Machine Learning · Statistics 2020-07-17 Ali Siahkoohi , Gabrio Rizzuti , Philipp A. Witte , Felix J. Herrmann

Inverse analysis has been utilized to understand unknown underground geological properties by matching the observational data with simulators. To overcome the underconstrained nature of inverse problems and achieve good performance, an…

Computational Physics · Physics 2022-08-10 Hao Wu , Sarah Greer , Daniel O'Malley

The amount and spatial pattern of heat extracted from cores of terrestrial planets is ultimately controlled by the thermal structure of the lower rocky mantle. Using the most common model to tackle this problem, a rapidly rotating and…

Earth and Planetary Astrophysics · Physics 2016-01-26 Wieland Dietrich , Kumiko Hori , Johannes Wicht

We are concerned with the inverse problem of identifying magnetic anomalies with varing parameters beneath the Earth using geomagnetic monitoring. Observations of the change in Earth's magnetic field--the secular variation--provide…

Analysis of PDEs · Mathematics 2019-04-19 Youjun Deng , Hongyu Liu , Wing-Yan Tsui