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Magnetic Resonance Imaging (MRI) has long been considered to be among "the gold standards" of diagnostic medical imaging. The long acquisition times, however, render MRI prone to motion artifacts, let alone their adverse contribution to the…

Image and Video Processing · Electrical Eng. & Systems 2021-04-14 Tomer Weiss , Ortal Senouf , Sanketh Vedula , Oleg Michailovich , Michael Zibulevsky , Alex Bronstein

Many problems in computational geometry are not stated in graph-theoretic terms, but can be solved efficiently by constructing an auxiliary graph and performing a graph-theoretic algorithm on it. Often, the efficiency of the algorithm…

Computational Geometry · Computer Science 2009-08-28 David Eppstein

Gradient-based algorithms, popular strategies to optimization problems, are essential for many modern machine-learning techniques. Theoretically, extreme points of certain cost functions can be found iteratively along the directions of the…

Quantum Physics · Physics 2021-04-07 Keren Li , Pan Gao , Shijie Wei , Jiancun Gao , Guilu Long

Gradient descent optimization algorithms, while increasingly popular, are often used as black-box optimizers, as practical explanations of their strengths and weaknesses are hard to come by. This article aims to provide the reader with…

Machine Learning · Computer Science 2017-06-16 Sebastian Ruder

In this paper, we consider a problem of learning supervised PageRank models, which can account for some properties not considered by classical approaches such as the classical PageRank algorithm. Due to huge hidden dimension of the…

Optimization and control of complex unsteady flows remains an important challenge due to the large cost of performing a function evaluation, i.e. a full computational fluid dynamics (CFD) simulation. Reducing the number of required function…

Fluid Dynamics · Physics 2023-01-31 A. Quirós Rodríguez , M. Fosas de Pando , T. Sayadi

Min-max optimization is emerging as a key framework for analyzing problems of robustness to strategically and adversarially generated data. We propose a random reshuffling-based gradient free Optimistic Gradient Descent-Ascent algorithm for…

Optimization and Control · Mathematics 2022-02-22 Chinmay Maheshwari , Chih-Yuan Chiu , Eric Mazumdar , S. Shankar Sastry , Lillian J. Ratliff

Learned iterative reconstruction algorithms for inverse problems offer the flexibility to combine analytical knowledge about the problem with modules learned from data. This way, they achieve high reconstruction performance while ensuring…

Image and Video Processing · Electrical Eng. & Systems 2022-10-24 Mareike Thies , Fabian Wagner , Mingxuan Gu , Lukas Folle , Lina Felsner , Andreas Maier

In this article we develop a gradient-based algorithm for the solution of multiobjective optimization problems with uncertainties. To this end, an additional condition is derived for the descent direction in order to account for…

Optimization and Control · Mathematics 2018-08-02 Sebastian Peitz , Michael Dellnitz

Motion artifacts can compromise the diagnostic value of computed tomography (CT) images. Motion correction approaches require a per-scan estimation of patient-specific motion patterns. In this work, we train a score-based model to act as a…

Computer Vision and Pattern Recognition · Computer Science 2024-04-24 Mareike Thies , Noah Maul , Siyuan Mei , Laura Pfaff , Nastassia Vysotskaya , Mingxuan Gu , Jonas Utz , Dennis Possart , Lukas Folle , Fabian Wagner , Andreas Maier

We present a practical approach to solving distance-based optimization problems using optical computing hardware. The objective is to minimize an energy function defined as the weighted sum of squared differences between measured distances…

Optics · Physics 2025-07-16 Guangyao Li , Richard Zhipeng Wang , Natalia G. Berloff

The need for fast and robust optimization algorithms are of critical importance in all areas of machine learning. This paper treats the task of designing optimization algorithms as an optimal control problem. Using regret as a metric for an…

Machine Learning · Computer Science 2021-01-21 Philippe Casgrain , Anastasis Kratsios

In this work, multi-variable derivative-free optimization algorithms for unconstrained optimization problems are developed. A novel procedure for approximating the gradient of multi-variable objective functions based on non-commutative maps…

Optimization and Control · Mathematics 2021-11-17 Jan Feiling , Mohamed-Ali Belabbas , Christian Ebenbauer

Incorporating a deep generative model as the prior distribution in inverse problems has established substantial success in reconstructing images from corrupted observations. Notwithstanding, the existing optimization approaches use gradient…

Machine Learning · Computer Science 2023-01-31 Tianci Liu , Tong Yang , Quan Zhang , Qi Lei

This work is concerned with applying iterative image reconstruction, based on constrained total-variation minimization, to low-intensity X-ray CT systems that have a high sampling rate. Such systems pose a challenge for iterative image…

Medical Physics · Physics 2016-11-17 Emil Y. Sidky , Rick Chartrand , Yuval Duchin , Christer Ullberg , Xiaochuan Pan

A challenge in high-dimensional inverse problems is developing iterative solvers to find the accurate solution of regularized optimization problems with low computational cost. An important example is computed tomography (CT) where both…

Numerical Analysis · Mathematics 2024-12-16 Alessandro Perelli , Carola-Bibiane Schonlieb , Matthias J. Ehrhardt

Much recent attention has been devoted to gradient descent algorithms where the steepest descent step size is replaced by a similar one from a previous iteration or gets updated only once every second step, thus forming a {\em faster…

Computer Vision and Pattern Recognition · Computer Science 2013-08-13 Hui Huang , Uri Ascher

Ptychography is a powerful computational imaging technique that transforms a collection of low-resolution images into a high-resolution sample reconstruction. Unfortunately, algorithms that are currently used to solve this reconstruction…

In this paper we present a new algorithmic realization of a projection-based scheme for general convex constrained optimization problem. The general idea is to transform the original optimization problem to a sequence of feasibility…

Optimization and Control · Mathematics 2019-11-12 Aviv Gibali , Karl-Heinz Küfer , Daniel Reem , Philipp Süss

This article presents a new and efficient alternative to well established algorithms for molecular geometry optimization. The new approach exploits the approximate decoupling of molecular energetics in a curvilinear internal coordinate…

Materials Science · Physics 2007-05-23 Károly Németh , Matt Challacombe
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