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We propose a high-order discontinuous Galerkin scheme for nonlinear acoustic waves on polytopic meshes. To model sound propagation with and without losses, we use Westervelt's nonlinear wave equation with and without strong damping.…

In this paper, we study the inverse boundary value problem for the wave equation with a view towards an explicit reconstruction procedure. We consider both the anisotropic problem where the unknown is a general Riemannian metric smoothly…

偏微分方程分析 · 数学 2017-10-10 Maarten de Hoop , Paul Kepley , Lauri Oksanen

We present a study of the numerical solution of the two dimensional electrical impedance tomography problem, with noisy measurements of the Dirichlet to Neumann map. The inversion uses parametrizations of the conductivity on optimal grids.…

数学物理 · 物理学 2015-06-03 Liliana Borcea , Fernando Guevara Vasquez , Alexander V. Mamonov

We study inverse boundary problems for third-order nonlinear tensorial perturbations of biharmonic operators on a bounded domain in $\mathbb{R}^n$, where $n\geq 3$. By imposing appropriate assumptions on the nonlinearity, we demonstrate…

偏微分方程分析 · 数学 2023-12-14 Sombuddha Bhattacharyya , Katya Krupchyk , Suman Kumar Sahoo , Gunther Uhlmann

We investigate the problem of recovering a partially observed high-rank matrix whose columns obey a nonlinear structure such as a union of subspaces, an algebraic variety or grouped in clusters. The recovery problem is formulated as the…

机器学习 · 统计学 2022-12-12 Florentin Goyens , Coralia Cartis , Armin Eftekhari

We study iterative signal reconstruction in computed tomography (CT), wherein measurements are produced by a linear transformation of the unknown signal followed by an exponential nonlinear map. Approaches based on pre-processing the data…

最优化与控制 · 数学 2024-07-19 Vasileios Charisopoulos , Rebecca Willett

We consider the identification of nonlinear diffusion coefficients of the form $a(t,u)$ or $a(u)$ in quasi-linear parabolic and elliptic equations. Uniqueness for this inverse problem is established under very general assumptions using…

偏微分方程分析 · 数学 2017-10-25 Herbert Egger , Jan-Frederik Pietschmann , Matthias Schlottbom

We consider a restricted Dirichlet-to-Neumann map associated to a wave type operator on a Riemannian manifold with boundary. The restriction corresponds to the case where the Dirichlet traces are supported on one subset of the boundary and…

偏微分方程分析 · 数学 2018-06-15 Yavar Kian , Yaroslav Kurylev , Matti Lassas , Lauri Oksanen

We consider a mathematical model of thermoacoustic tomography and other multi-wave imaging techniques with variable sound speed and attenuation. We find that a Neumann series reconstruction algorithm, previously studied under the assumption…

偏微分方程分析 · 数学 2012-12-21 Andrew Homan

In this paper we consider the inverse problem of determining on a compact Riemannian manifold the metric tensor in the wave equation with Dirichlet data from measured Neumann boundary observations. This information is enclosed in the…

偏微分方程分析 · 数学 2021-02-11 Mourad Bellassoued

We propose a self-adaptive absorbing technique for quasilinear ultrasound waves in two- and three-dimensional computational domains. As a model for the nonlinear ultrasound propagation in thermoviscous fluids, we employ Westervelt's wave…

数值分析 · 数学 2019-05-01 Markus Muhr , Vanja Nikolić , Barbara Wohlmuth

We consider the semilinear wave equation $\Box_g u+a u^4=0$, $a\neq 0$, on a Lorentzian manifold $(M,g)$ with timelike boundary. We show that from the knowledge of the Dirichlet-to-Neumann map one can recover the metric $g$ and the…

偏微分方程分析 · 数学 2021-03-16 Peter Hintz , Gunther Uhlmann , Jian Zhai

In this paper, we are interested in the classical problem of restoring data degraded by a convolution and the addition of a white Gaussian noise. The originality of the proposed approach is two-fold. Firstly, we formulate the restoration…

统计方法学 · 统计学 2015-05-13 Jean-Christophe Pesquet , Amel Benazza-Benyahia , Caroline Chaux

We study the inverse problem of unique recovery of a complex-valued scalar function $V:\mathcal M \times \mathbb C\to \mathbb C$, defined over a smooth compact Riemannian manifold $(\mathcal M,g)$ with smooth boundary, given the Dirichlet…

偏微分方程分析 · 数学 2023-05-10 Ali Feizmohammadi , Lauri Oksanen

The main goal of this article is to study a Calder\'on type inverse problem for certain viscous nonlocal wave equations. We show that the partial Dirichlet to Neumann map uniquely determines on the one hand linear perturbations and on the…

偏微分方程分析 · 数学 2026-01-06 Philipp Zimmermann

We propose a new numerical method to reconstruct the isotropic electrical conductivity from measured restricted Dirichlet-to-Neumann map data in electrical impedance tomography (EIT) model. "Restricted Dirichlet-to-Neumann (DtN) map data"…

数值分析 · 数学 2019-02-20 Michael V. Klibanov , Jingzhi Li , Wenlong Zhang

We consider an inverse boundary value problem for a semilinear wave equation on a time-dependent Lorentzian manifold with time-like boundary. The time-dependent coefficients of the nonlinear terms can be recovered in the interior from the…

偏微分方程分析 · 数学 2021-01-27 Peter Hintz , Gunther Uhlmann , Jian Zhai

We study the inverse boundary value problem for the Helmholtz equation using the Dirichlet-to-Neumann map at selected frequencies as the data. A conditional Lipschitz stability estimate for the inverse problem holds in the case of…

偏微分方程分析 · 数学 2019-06-05 Elena Beretta , Maarten V. de Hoop , Florian Faucher , Otmar Scherzer

In this paper, a methodology is investigated for signal recovery in the presence of non-Gaussian noise. In contrast with regularized minimization approaches often adopted in the literature, in our algorithm the regularization parameter is…

最优化与控制 · 数学 2017-01-23 Yosra Marnissi , Yuling Zheng , Emilie Chouzenoux , Jean-Christophe Pesquet

Ultrasound Tomography has seen a revival of interest in the past decade, especially for breast imaging, due to improvements in both ultrasound and computing hardware. In particular, three-dimensional ultrasound tomography, a fully…

计算物理 · 物理学 2020-05-27 Ashkan Javaherian , Felix Lucka , Ben Cox