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In this paper, we propose a double iteratively reweighted algorithm to solve nonconvex and nonsmooth optimization problems, where both the objectives and constraint functions are formulated by concave compositions to promote group-sparse…

Optimization and Control · Mathematics 2025-11-25 Wanqin Nie , Kai Tu , Minglu Ye , Shuqin Sun

We propose a flexible yet interpretable model for high-dimensional data with time-varying second order statistics, motivated and applied to functional neuroimaging data. Motivated by the neuroscience literature, we factorize the covariances…

Machine Learning · Statistics 2021-07-20 Katherine Tsai , Mladen Kolar , Oluwasanmi Koyejo

Using convex combination and linesearch techniques, we introduce a novel primal-dual algorithm for solving structured convex-concave saddle point problems with a generic smooth nonbilinear coupling term. Our adaptive linesearch strategy…

Optimization and Control · Mathematics 2024-01-17 Xiaokai Chang , Junfeng Yang , Hongchao Zhang

We consider an inertial primal-dual fixed point algorithm (IPDFP) to compute the minimizations of the following Problem (1.1). This is a full splitting approach, in the sense that the nonsmooth functions are processed individually via their…

Optimization and Control · Mathematics 2016-04-20 Meng Wen , Yu-Chao Tang , Jigen Peng

In this work, we investigate the application of deep learning methods for computed tomography in the context of having a low-data regime. As motivation, we review some of the existing approaches and obtain quantitative results after…

Image and Video Processing · Electrical Eng. & Systems 2021-04-20 Daniel Otero Baguer , Johannes Leuschner , Maximilian Schmidt

In parallel magnetic resonance imaging (pMRI) reconstruction without using estimation of coil sensitivity functions, one group of algorithms reconstruct sensitivity encoded images of the coils first followed by the magnitude only image…

Medical Physics · Physics 2013-11-12 Cishen Zhang , Ifat Al Baqee

Digital breast tomosynthesis is rapidly replacing digital mammography as the basic x-ray technique for evaluation of the breasts. However, the sparse sampling and limited angular range gives rise to different artifacts, which manufacturers…

Medical Physics · Physics 2018-08-15 Nikita Moriakov , Koen Michielsen , Jonas Adler , Ritse Mann , Ioannis Sechopoulos , Jonas Teuwen

The Stochastic Primal-Dual Hybrid Gradient (SPDHG) was proposed by Chambolle et al. (2018) and is an efficient algorithm to solve some nonsmooth large-scale optimization problems. In this paper we prove its almost sure convergence for…

Optimization and Control · Mathematics 2021-04-02 Eric B. Gutierrez , Claire Delplancke , Matthias J. Ehrhardt

The inversion of linear systems is a fundamental step in many inverse problems. Computational challenges exist when trying to invert large linear systems, where limited computing resources mean that only part of the system can be kept in…

Distributed, Parallel, and Cluster Computing · Computer Science 2017-09-05 Yushan Gao , Thomas Blumensath

In this paper, we study communication efficient distributed algorithms for distributionally robust federated learning via periodic averaging with adaptive sampling. In contrast to standard empirical risk minimization, due to the minimax…

Machine Learning · Computer Science 2021-02-26 Yuyang Deng , Mohammad Mahdi Kamani , Mehrdad Mahdavi

Next-generation radio interferometers like the Square Kilometer Array have the potential to unlock scientific discoveries thanks to their unprecedented angular resolution and sensitivity. One key to unlocking their potential resides in…

Instrumentation and Methods for Astrophysics · Physics 2024-08-01 Tobías I. Liaudat , Matthijs Mars , Matthew A. Price , Marcelo Pereyra , Marta M. Betcke , Jason D. McEwen

The ability of widely distributed radar systems to capture diverse spatial scattering properties substantially improves radar imaging performance. Traditional imaging methods leverage regularized optimization techniques to reconstruct…

Signal Processing · Electrical Eng. & Systems 2023-07-18 Ahmed Murtada , Bhavani Shankar Mysore Rama Rao , Udo Schroeder

The 2-D phase unwrapping problem aims at retrieving a "phase" image from its modulo $2\pi$ observations. Many applications, such as interferometry or synthetic aperture radar imaging, are concerned by this problem since they proceed by…

Optimization and Control · Mathematics 2014-07-31 Adriana Gonzalez , Laurent Jacques

The advent of enhanced technologies in radio interferometry and the perspective of the SKA telescope bring new challenges in image reconstruction. One of these challenges is the spatio-spectral reconstruction of large (Terabytes) data cubes…

Instrumentation and Methods for Astrophysics · Physics 2016-03-07 Jérémy Deguignet , André Ferrari , David Mary , Chiara Ferrari

In this paper, we study the resource allocation for an orthogonal frequency division multiple access (OFDMA) radio system employing a full-duplex base station for serving multiple half-duplex downlink and uplink users simultaneously. The…

Information Theory · Computer Science 2017-05-08 Yan Sun , Derrick Wing Kwan Ng , Robert Schober

This paper investigates accelerating the convergence of distributed optimization algorithms on non-convex problems. We propose a distributed primal-dual stochastic gradient descent~(SGD) equipped with "powerball" method to accelerate. We…

Optimization and Control · Mathematics 2021-10-15 Shengjun Zhang , Colleen P. Bailey

This paper addresses the problem of nonconvex nonsmooth decentralised optimisation in multi-agent networks with undirected connected communication graphs. Our contribution lies in introducing an algorithmic framework designed for the…

Optimization and Control · Mathematics 2023-12-08 Behnam Mafakheri , Jonathan H. Manton , Iman Shames

Multidimensional imaging, capturing image data in more than two dimensions, has been an emerging field with diverse applications. Due to the limitation of two-dimensional detectors in obtaining the high-dimensional image data, computational…

Image and Video Processing · Electrical Eng. & Systems 2020-06-16 Didem Dogan , Figen S. Oktem

Distributed algorithms provide flexibility over centralized algorithms for resource allocation problems, e.g., cyber-physical systems. However, the distributed nature of these algorithms often makes the systems susceptible to…

Optimization and Control · Mathematics 2019-09-11 Cesar A. Uribe , Hoi-To Wai , Mahnoosh Alizadeh

This paper proposes a randomized optimization framework for constrained signal reconstruction, where the word "constrained" implies that data-fidelity is imposed as a hard constraint instead of adding a data-fidelity term to an objective…

Optimization and Control · Mathematics 2024-06-28 Shunsuke Ono