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Thermo-acoustic tomography is a non-invasive medical imaging technique, constituting a precise and cheap alternative to X-imaging. The principle is to excite a body to reconstruct with a pulse inducing an inhomogeneous heating and therefore…

Analysis of PDEs · Mathematics 2019-07-24 Maïtine Bergounioux , Elie Bretin , Yannick Privat

In this work, we systematically investigate the quantum-information diagnostics of cosmological perturbations with a nontrivial sound speed, utilizing a normalized open two-mode squeezed-state framework. Rather than introducing new…

General Relativity and Quantum Cosmology · Physics 2026-04-24 Shi-Cheng Liu , Lei-Hua Liu , Bichu Li , Hai-Qing Zhang , Peng-Zhang He

Thermoacoustic tomography (TAT) is an imaging modality based on the thermoacoustic effect. In TAT, a short microwave or radio wave pulse is directed to the imaged target. The energy of the electromagnetic pulse is absorbed depending on the…

Computational Physics · Physics 2025-11-11 Teemu Sahlström , Tanja Tarvainen

The importance of ultrasound is well established in the imaging of human tissue. In order to enhance image quality by exploiting nonlinear effects, recently techniques such as harmonic imaging and nonlinearity parameter tomography have been…

Analysis of PDEs · Mathematics 2025-02-13 Barbara Kaltenbacher

A new dispersion equation is obtained for a non-equilibrium medium with an exponential relaxation model of a vibrationally excited gas. We have researched the dependencies of the pump source and the heat removal on the medium thermodynamic…

Fluid Dynamics · Physics 2018-05-10 S. S. Khrapov , A. V. Khoperskov

In recent years, several numerical methods for solving the unique continuation problem for the wave equation in a homogeneous medium with given data on the lateral boundary of the space-time cylinder have been proposed. This problem enjoys…

Numerical Analysis · Mathematics 2026-01-14 Erik Burman , Janosch Preuss , Tim van Beeck

Variable-amplitude oscillatory shear tests are emerging as powerful tools to investigate and quantify the nonlinear rheology of amorphous solids, complex fluids and biological materials. Quite a few recent experimental and atomistic…

Materials Science · Physics 2015-06-19 Nathan Perchikov , Eran Bouchbinder

We consider an inverse problem governed by the Westervelt equation with linear diffusivity and quadratic-type nonlinearity. The objective of this problem is to recover all the coefficients of this nonlinear partial differential equation. We…

Analysis of PDEs · Mathematics 2025-09-16 Sebastian Acosta , Benjamin Palacios

In the present article the diffusion equation is used to model the spatio-temporal dynamics of a tumor, taking into account the heterogeneous of the medium. This approach makes it possible to take into account the complex geometric shape of…

Biological Physics · Physics 2023-02-07 Maxim V. Polyakov , Valeria V. Ten

Ultrasound is an adjunct tool to mammography that can quickly and safely aid physicians with diagnosing breast abnormalities. Clinical ultrasound often assumes a constant sound speed to form B-mode images for diagnosis. However, the various…

Computer Vision and Pattern Recognition · Computer Science 2023-02-08 Walter A. Simson , Magdalini Paschali , Vasiliki Sideri-Lampretsa , Nassir Navab , Jeremy J. Dahl

Passive acoustic mapping enables the spatial mapping and temporal monitoring of cavitation activity, playing a crucial role in therapeutic ultrasound applications. Most conventional beamforming methods, whether implemented in the time or…

Signal Processing · Electrical Eng. & Systems 2025-11-26 Tatiana Gelvez-Barrera , Barbara Nicolas , Denis Kouamé , Bruno Gilles , Adrian Basarab

In this work, we consider the propagation of acoustic waves in unbounded domains characterized by a constant wavenumber, except possibly in a bounded region. The geometry of this inhomogeneity is assumed to be uncertain, and we are…

Numerical Analysis · Mathematics 2024-07-17 Fernando Henríquez , Ignacio Labarca-Figueroa

This article proposes an in-depth investigation into the emergence of thermoacoustic waves from a variational formalism rooted in non-equilibrium thermodynamics. Differing from traditional approaches based on linear simplifications, this…

Classical Physics · Physics 2025-07-14 Gabriel R. de Andrade Silva

In this paper, we consider Carleman estimates and inverse problems for the coupled quantitative thermoacoustic equations. In Part I, we establish Carleman estimates for the coupled quantitative thermoacoustic equations by assuming that the…

Analysis of PDEs · Mathematics 2020-05-06 Yunxia Shang , Shumin Li

Motivated by the propagation of nonlinear sound waves through relaxing hereditary media, we study a nonlocal third-order Jordan-Moore-Gibson-Thompson acoustic wave equation. Under the assumption that the relaxation kernel decays…

Analysis of PDEs · Mathematics 2020-10-06 Vanja Nikolić , Belkacem Said-Houari

Consider the wave propagation in a two-layered medium consisting of a homogeneous compressible air or fluid on top of a homogeneous isotropic elastic solid. The interface between the two layers is assumed to be an unbounded rough surface.…

Analysis of PDEs · Mathematics 2016-08-22 Yixian Gao , Peijun Li , Bo Zhang

In ultrasound tomography, the speed of sound inside an object is estimated based on acoustic measurements carried out by sensors surrounding the object. An accurate forward model is a prominent factor for high-quality image reconstruction,…

Image and Video Processing · Electrical Eng. & Systems 2021-11-24 Janne Koponen , Timo Lähivaara , Jari Kaipio , Marko Vauhkonen

Sound speed heterogeneities can create aberrations in B-mode ultrasound images by inducing tissue-dependent delays and diffractive effects that conventional beamforming does not incorporate. By using the Fourier split-step method to…

Medical Physics · Physics 2026-05-01 Rehman Ali , Trevor M. Mitcham , Marvin M. Doyley , Nebojsa Duric , Jeremy J. Dahl

This letter is concerned with solving continuous-discrete Gaussian smoothing problems by using the Taylor moment expansion (TME) scheme. In the proposed smoothing method, we apply the TME method to approximate the transition density of the…

Numerical Analysis · Mathematics 2021-11-05 Zheng Zhao , Simo Särkkä

We analyze diffusion processes with finite propagation speed in a non-homogeneous medium in terms of the heterogeneous telegrapher's equation. In the diffusion limit of infinite-velocity propagation we recover the results for the…

Statistical Mechanics · Physics 2022-11-18 Trifce Sandev , Ljupco Kocarev , Ralf Metzler , Aleksei Chechkin