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This paper studies adaptive least-squares finite element methods for convection-dominated diffusion-reaction problems. The least-squares methods are based on the first-order system of the primal and dual variables with various ways of…

Numerical Analysis · Mathematics 2023-01-30 Zhiqiang Cai , Binghe Chen , Jing Yang

This paper focuses on developing a reduction-based algebraic multigrid method that is suitable for solving general (non)symmetric linear systems and is naturally robust from pure advection to pure diffusion. Initial motivation comes from a…

Numerical Analysis · Mathematics 2024-05-16 Ahsan Ali , James Brannick , Karsten Kahl , Oliver A. Krzysik , Jacob B. Schroder , Ben S. Southworth

The efficient and reliable approximation of convection-dominated problems continues to remain a challenging task. To overcome the difficulties associated with the discretization of convection-dominated equations, stabilization techniques…

Numerical Analysis · Mathematics 2022-12-15 Marius Paul Bruchhäuser , Kristina Schwegler , Markus Bause

We propose an automated nonlinear model reduction and mesh adaptation framework for rapid and reliable solution of parameterized advection-dominated problems, with emphasis on compressible flows. The key features of our approach are…

Numerical Analysis · Mathematics 2023-08-04 Nicolas Barral , Tommaso Taddei , Ishak Tifouti

Many real-world systems modeled using partial differential equations (PDEs) involve unknown parameters that must be estimated from limited, noisy system observations. While typically assumed to be constants, some of these unobserved…

Methodology · Statistics 2025-08-19 Andrea Arnold

This paper introduces a novel variational Bayesian method that integrates Tucker decomposition for efficient high-dimensional inverse problem solving. The method reduces computational complexity by transforming variational inference from a…

Machine Learning · Computer Science 2026-03-18 Qing-Mei Yang , Da-Qing Zhang

The aim of this paper is to discuss potential advances in PET kinetic models and direct reconstruction of kinetic parameters. As a prominent example we focus on a typical task in perfusion imaging and derive a system of…

Optimization and Control · Mathematics 2014-11-20 Louise Reips , Martin Burger , Ralf Engbers

Problems with dominant advection, discontinuities, travelling features, or shape variations are widespread in computational mechanics. However, classical linear model reduction and interpolation methods typically fail to reproduce even…

Numerical Analysis · Mathematics 2025-01-03 Tobias Long , Robert Barnett , Richard Jefferson-Loveday , Giovanni Stabile , Matteo Icardi

Estimating and quantifying uncertainty in unknown system parameters from limited data remains a challenging inverse problem in a variety of real-world applications. While many approaches focus on estimating constant parameters, a subset of…

Methodology · Statistics 2023-05-09 Andrea Arnold

Blind super-resolution methods based on stable diffusion showcase formidable generative capabilities in reconstructing clear high-resolution images with intricate details from low-resolution inputs. However, their practical applicability is…

Computer Vision and Pattern Recognition · Computer Science 2024-12-30 Rui Xie , Chen Zhao , Kai Zhang , Zhenyu Zhang , Jun Zhou , Jian Yang , Ying Tai

We introduce the BIR-Adapter, a parameter-efficient diffusion adapter for blind image restoration. Diffusion-based restoration methods have demonstrated promising performance in addressing this fundamental problem in computer vision,…

Computer Vision and Pattern Recognition · Computer Science 2026-04-28 Cem Eteke , Alexander Griessel , Wolfgang Kellerer , Eckehard Steinbach

In this work, we propose viable and efficient strategies for stabilized parametrized advection dominated problems, with random inputs. In particular, we investigate the combination of wRB (weighted reduced basis) method for stochastic…

Numerical Analysis · Mathematics 2018-11-05 Davide Torlo , Francesco Ballarin , Gianluigi Rozza

The problem of the resolution of turbulent flows in adaptive mesh refinement (AMR) simulations is investigated by means of 3D hydrodynamical simulations in an idealised setup, representing a moving subcluster during a merger event. AMR…

Astrophysics · Physics 2009-11-13 L. Iapichino , J. Adamek , W. Schmidt , J. C. Niemeyer

We propose, analyze, and investigate numerically a novel feedback control strategy for high Reynolds number flows. For both the continuous and the discrete (finite element) settings, we prove that the new strategy yields accurate results…

Numerical Analysis · Mathematics 2025-07-11 Maria Strazzullo , Francesco Ballarin , Traian Iliescu , Claudio Canuto

We present a novel hyperviscosity formulation for stabilizing RBF-FD discretizations of the advection-diffusion equation. The amount of hyperviscosity is determined quasi-analytically for commonly-used explicit, implicit, and…

Numerical Analysis · Mathematics 2018-08-01 Varun Shankar , Aaron L. Fogelson

Solving inverse problems is central to a variety of important applications, such as biomedical image reconstruction and non-destructive testing. These problems are characterized by the sensitivity of direct solution methods with respect to…

Numerical Analysis · Mathematics 2023-05-17 Simon Göppel , Jürgen Frikel , Markus Haltmeier

This article provides next step towards solving speed bottleneck of any system that intensively uses convolutions operations (e.g. CNN). Method described in the article is applied on deformable part models (DPM) algorithm. Method described…

Computer Vision and Pattern Recognition · Computer Science 2017-07-12 D. V. Parkhomenko , I. L. Mazurenko

In image deconvolution problems, the diagonalization of the underlying operators by means of the FFT usually yields very large speedups. When there are incomplete observations (e.g., in the case of unknown boundaries), standard…

Computer Vision and Pattern Recognition · Computer Science 2016-08-31 Miguel Simões , Luis B. Almeida , José Bioucas-Dias , Jocelyn Chanussot

We propose a method to stabilise a solution to equations describing the interface of thin liquid films falling under gravity with a finite number of actuators and restricted observations. As for many complex systems, full observation of the…

Optimization and Control · Mathematics 2024-07-10 Oscar A. Holroyd , Radu Cimpeanu , Susana N. Gomes

We present a new hyperviscosity formulation for stabilizing radial basis function-finite difference (RBF-FD) discretizations of advection-diffusion-reaction equations on manifolds $\mathbb{M} \subset \mathbb{R}^3$ of co-dimension one. Our…

Numerical Analysis · Mathematics 2020-04-27 Varun Shankar , Grady B. Wright , Akil Narayan