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We present two approximation methods for computing eigenfrequencies and eigenmodes of large-scale nonlinear eigenvalue problems resulting from boundary element method (BEM) solutions of some types of acoustic eigenvalue problems in…

Numerical Analysis · Mathematics 2024-09-23 Mohamed El-Guide , Agnieszka Miedlar , Yousef Saad

Numerically solving high-dimensional random parametric PDEs poses a challenging computational problem. It is well-known that numerical methods can greatly benefit from adaptive refinement algorithms, in particular when functional…

Numerical Analysis · Mathematics 2024-07-29 Martin Eigel , Nando Hegemann

Despite its wide use in medicine, ultrasound imaging faces several challenges related to its poor signal-to-noise ratio and several sources of noise and artefacts. Enhancing ultrasound image quality involves balancing concurrent factors…

Computer Vision and Pattern Recognition · Computer Science 2024-10-28 Yuxin Zhang , Clément Huneau , Jérôme Idier , Diana Mateus

This paper investigates the simultaneous identification of a spatially dependent potential and the initial condition in a subdiffusion model based on two terminal observations. The existence, uniqueness, and conditional stability of the…

Numerical Analysis · Mathematics 2025-10-28 Xu Wu , Jiang Yang , Zhi Zhou

Diffusion models have established new state of the art in a multitude of computer vision tasks, including image restoration. Diffusion-based inverse problem solvers generate reconstructions of exceptional visual quality from heavily…

Image and Video Processing · Electrical Eng. & Systems 2024-08-21 Zalan Fabian , Berk Tinaz , Mahdi Soltanolkotabi

The conditional diffusion model (CDM) enhances the standard diffusion model by providing more control, improving the quality and relevance of the outputs, and making the model adaptable to a wider range of complex tasks. However, inaccurate…

Machine Learning · Computer Science 2024-08-07 Weifeng Xu , Xiang Zhu , Xiaoyong Li

In this paper, we study both the direct and inverse random source problems associated with the multi-term time-fractional diffusion-wave equation driven by a fractional Brownian motion. Regarding the direct problem, the well-posedness is…

Analysis of PDEs · Mathematics 2023-11-03 Xiaoli Feng , Qiang Yao , Peijun Li , Xu Wang

The harmonic balance method is the most commonly used method for solving periodic solutions of nonlinear dynamic systems, but the high-order approximation of nonlinear terms requires sophisticated formula derivation, which limits its…

Numerical Analysis · Mathematics 2023-08-02 Dai Honghua , Wang Qisi , Yan Zipu , Yue Xiaokui

This paper investigates an inverse source problem for space-time fractional diffusion equations from a posteriori interior measurements. The uniqueness result is established by the memory effect of fractional derivatives and the unique…

Numerical Analysis · Mathematics 2025-10-24 Kai Yu , Zhiyuan Li , Yikan Liu

This paper develops and analyzes a general iterative framework for solving parameter-dependent and random convection-diffusion problems. It is inspired by the multi-modes method of [7,8] and the ensemble method of [20] and extends those…

Numerical Analysis · Mathematics 2021-10-22 Xiaobing Feng , Yan Luo , Liet Vo , Zhu Wang

This paper concerns the reconstruction of a diffusion coefficient in an elliptic equation from knowledge of several power densities. The power density is the product of the diffusion coefficient with the square of the modulus of the…

Analysis of PDEs · Mathematics 2012-03-07 Guillaume Bal , Eric Bonnetier , Francois Monard , Faouzi Triki

We discuss the identification of a time-dependent potential in a time-fractional diffusion model from a boundary measurement taken at a single point. Theoretically, we establish a conditional Lipschitz stability for this inverse problem.…

Numerical Analysis · Mathematics 2024-07-23 Siyu Cen , Kwancheol Shin , Zhi Zhou

We consider the problem of reconstruction of Cauchy data for the wave equation in $\mathbb{R}^1$ by the measurements of its solution on the boundary of the finite interval. This is a one-dimensional model for the multidimensional problem of…

Analysis of PDEs · Mathematics 2025-05-26 D. Langemann , A. S. Mikhaylov , V. S. Mikhaylov

Diffusion MRI is a well established imaging modality providing a powerful way to probe the structure of the white matter non-invasively. Despite its potential, the intrinsic long scan times of these sequences have hampered their use in…

Quantitative Methods · Quantitative Biology 2013-12-31 Alessandro Daducci , Dimitri Van De Ville , Jean-Philippe Thiran , Yves Wiaux

We propose regularization schemes for deformable registration and efficient algorithms for their numerical approximation. We treat image registration as a variational optimal control problem. The deformation map is parametrized by its…

Optimization and Control · Mathematics 2016-09-09 Andreas Mang , George Biros

This study aims to construct a stable, high-order compact finite difference method for solving Sobolev-type equations with Dirichlet boundary conditions in one-space dimension. Approximation of higher-order mixed derivatives in some…

Numerical Analysis · Mathematics 2025-06-05 Lavanya V Salian , Samala Rathan , Rakesh Kumar

The two promising methods for capturing high-speed flows are local artificial diffusivity (LAD) and centralised gradient-based reconstruction (C-GBR), the former being computationally economical and the latter being more robust and stable…

Fluid Dynamics · Physics 2025-11-25 R. R. Kumar , S. Saini , N. R. Vadlamani , A. S. Chamarthi

Despite its generality and powerful convergence properties, Milstein's method for functionals of spatially bounded stochastic differential equations is widely regarded as difficult to implement. This has likely prevented it from being…

Numerical Analysis · Mathematics 2018-11-22 Francisco Bernal

We present a recursive algorithm for multi-coefficient inversion in nonlinear Helmholtz equations with polynomial-type nonlinearities, utilizing the linearized Dirichlet-to-Neumann map as measurement data. To achieve effective recursive…

Analysis of PDEs · Mathematics 2025-09-09 Shuai Lu , Boxi Xu

We study the interplay between reversibility, geometry, and the choice of multiplicative noise (in particular It\^{o}, Stratonovich, Klimontovich) in stochastic differential equations (SDEs). Building on a unified geometric framework, we…

Probability · Mathematics 2025-11-06 Mario Ayala , Nicolas Dirr , Grigorios A. Pavliotis , Johannes Zimmer