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The goal of this work is to improve focusing of high-intensity ultrasound by modifying the geometry of acoustic lenses through shape optimization. The shape optimization problem is formulated by introducing a tracking-type cost functional…

Optimization and Control · Mathematics 2017-12-15 Markus Muhr , Vanja Nikolić , Barbara Wohlmuth , Linus Wunderlich

This work deals with the convergence analysis of parabolic perturbations to quasilinear wave equations on smooth bounded domains. In particular, we consider wave equations with nonlinearities of quadratic type, which cover the two classical…

Analysis of PDEs · Mathematics 2021-09-29 Barbara Kaltenbacher , Vanja Nikolić

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

We are interested in shape sensitivity analysis for an optimization problem arising in medical applications of high intensity focused ultrasound. The goal is to find the optimal shape of a focusing acoustic lens so that the desired acoustic…

Optimization and Control · Mathematics 2015-06-10 Vanja Nikolic , Barbara Kaltenbacher

Accurate simulation of nonlinear acoustic waves is essential for the continued development of a wide range of (high-intensity) focused ultrasound applications. This article explores mixed finite element formulations of classical strongly…

Numerical Analysis · Mathematics 2022-09-08 Mostafa Meliani , Vanja Nikolić

Solutions of nonlinear acoustic equations describing propagation of strong sound pulses with account of curvature of wave fronts in multi-dimensional geometry are obtained from simple physical considerations. The form of these solutions…

Pattern Formation and Solitons · Physics 2016-02-25 A. M. Kamchatnov , M. V. Pavlov

This work is concerned with the study of fundamental models from nonlinear acoustics. In Part~I, a hierarchy of nonlinear damped wave equations arising in the description of sound propagation in thermoviscous fluids is deduced. In…

Analysis of PDEs · Mathematics 2017-08-22 Barbara Kaltenbacher , Mechthild Thalhammer

Heating generated by high-intensity focused ultrasound waves is central to many emerging medical applications, including non-invasive cancer therapy and targeted drug delivery. In this study, we aim to gain a fundamental understanding of…

Numerical Analysis · Mathematics 2025-10-03 Julio Careaga , Benjamin Dörich , Vanja Nikolić

A gradient-based method for shape optimization problems constrained by the acoustic wave equation is presented. The method makes use of high-order accurate finite differences with summation-by-parts properties on multiblock curvilinear…

Numerical Analysis · Mathematics 2024-05-09 Gustav Eriksson , Vidar Stiernström

We consider an undetermined coefficient inverse problem for a nonlinear partial differential equation describing high intensity ultrasound propagation as widely used in medical imaging and therapy. The usual nonlinear term in the standard…

Numerical Analysis · Mathematics 2022-04-13 Barbara Kaltenbacher , William Rundell

In this paper, we consider an inverse problem for a nonlinear wave equation with a damping term and a general nonlinear term. This problem arises in nonlinear acoustic imaging and has applications in medical imaging and other fields. The…

Analysis of PDEs · Mathematics 2023-03-01 Yang Zhang

The derivation of different models of non linear acoustic in thermo-ellastic media as the Kuznetsov equation, the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation and the Nonlinear Progressive wave Equation (NPE) from an isentropic…

Analysis of PDEs · Mathematics 2018-11-28 Adrien Dekkers , Vladimir Khodygo , Anna Rozanova-Pierrat

We investigate a quasilinear initial-boundary value problem for Kuznetsov's equation with non-homogeneous Dirichlet boundary conditions. This is a model in nonlinear acoustics which describes the propagation of sound in fluidic media with…

Analysis of PDEs · Mathematics 2012-09-10 Stefan Meyer , Mathias Wilke

Optimal control of nonlinear acoustic waves is relevant in many medical ultrasound technologies, ranging from cancer therapy to targeted drug delivery, where it can help guide the precise deposition of acoustic energy. In this work, we…

Optimization and Control · Mathematics 2025-11-20 Vanja Nikolić , Belkacem Said-Houari

We consider an inverse problem arising in nonlinear ultrasound imaging. The propagation of ultrasound waves is modeled by a quasilinear wave equation. We make measurements at the boundary of the medium encoded in the Dirichlet-to-Neumann…

Analysis of PDEs · Mathematics 2022-03-08 Gunther Uhlmann , Yang Zhang

In ultrasonics, nonlocal quasilinear wave equations arise when taking into account a class of heat flux laws of Gurtin--Pipkin type within the system of governing equations of sound motion. The present study extends previous work by the…

Analysis of PDEs · Mathematics 2023-08-22 B. Kaltenbacher , M. Meliani , V. Nikolić

We investigate models for nonlinear ultrasound propagation in soft biological tissue based on the one that serves as the core for the software package k-Wave. The systems are solved for the acoustic particle velocity, mass density, and…

Analysis of PDEs · Mathematics 2024-06-03 Ben Cox , Barbara Kaltenbacher , Vanja Nikolić , Felix Lucka

In this paper, we propose a level set-based shape optimization method for acoustic wave propagation problems with a deformable structure. First, we propose a mathematical model for acoustic wave propagation with a deformed structure based…

Computational Engineering, Finance, and Science · Computer Science 2023-04-04 Yuki Noguchi , Takayuki Yamada

When high-frequency sound waves travel through media with anomalous diffusion, such as biological tissues, their motion can be described by nonlinear wave equations of fractional higher order. These can be understood as nonlocal…

Analysis of PDEs · Mathematics 2023-10-31 Vanja Nikolić

We propose and study several inverse problems associated with the nonlinear progressive waves that arise in infrasonic inversions. The nonlinear progressive equation (NPE) is of a quasilinear form $\partial_t^2 u=\Delta f(x, u)$ with $f(x,…

Analysis of PDEs · Mathematics 2023-08-16 Yan Jiang , Hongyu Liu , Tianhao Ni , Kai Zhang
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