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The inversion of two-dimensional NMR data is an ill-posed problem related to the numerical computation of the inverse Laplace transform. In this paper we present the 2DUPEN algorithm that extends the Uniform Penalty (UPEN) algorithm…

Numerical Analysis · Mathematics 2016-12-21 V. Bortolotti , R. J. S. Brown , P. Fantazzini , G. Landi , F. Zama

This study examines, in the framework of variational regularization methods, a multi-penalty regularization approach which builds upon the Uniform PENalty (UPEN) method, previously proposed by the authors for Nuclear Magnetic Resonance…

Numerical Analysis · Mathematics 2025-02-20 Villiam Bortolotti , Germana Landi , Fabiana Zama

Translating machine learning algorithms into clinical applications requires addressing challenges related to interpretability, such as accounting for the effect of confounding variables (or metadata). Confounding variables affect the…

Machine Learning · Computer Science 2022-07-12 Anthony Vento , Qingyu Zhao , Robert Paul , Kilian M. Pohl , Ehsan Adeli

For many algorithms, parameter tuning remains a challenging and critical task, which becomes tedious and infeasible in a multi-parameter setting. Multi-penalty regularization, successfully used for solving undetermined sparse regression of…

Machine Learning · Statistics 2017-10-12 Markus Grasmair , Timo Klock , Valeriya Naumova

Inspired by several recent developments in regularization theory, optimization, and signal processing, we present and analyze a numerical approach to multi-penalty regularization in spaces of sparsely represented functions. The sparsity…

Numerical Analysis · Mathematics 2014-11-25 Valeriya Naumova , Steffen Peter

The low-rank matrix reconstruction (LRMR) approach is widely used in direction-of-arrival (DOA) estimation. As the rank norm penalty in an LRMR is NP-hard to compute, the nuclear norm (or the trace norm for a positive semidefinite (PSD)…

Information Theory · Computer Science 2017-12-07 Xiaohuan Wu , Wei-Ping Zhu , Jun Yan

Owing to the edge preserving ability and low computational cost of the total variation (TV), variational models with the TV regularization have been widely investigated in the field of multiplicative noise removal. The key points of the…

Computer Vision and Pattern Recognition · Computer Science 2015-03-18 Dai-Qiang Chen , Li-Zhi Cheng

In this work we consider numerical efficiency and convergence rates for solvers of non-convex multi-penalty formulations when reconstructing sparse signals from noisy linear measurements. We extend an existing approach, based on reduction…

Information Theory · Computer Science 2021-01-15 Zeljko Kereta , Johannes Maly , Valeriya Naumova

Fitting a matrix of a given rank to data in a least squares sense can be done very effectively using 2nd order methods such as Levenberg-Marquardt by explicitly optimizing over a bilinear parameterization of the matrix. In contrast, when…

Computer Vision and Pattern Recognition · Computer Science 2020-07-10 José Pedro Iglesias , Carl Olsson , Marcus Valtonen Örnhag

In this work, we describe a new approach that uses deep neural networks (DNN) to obtain regularization parameters for solving inverse problems. We consider a supervised learning approach, where a network is trained to approximate the…

Numerical Analysis · Mathematics 2021-04-15 Babak Maboudi Afkham , Julianne Chung , Matthias Chung

We tackle the problem of penalty selection of regularization on the basis of the minimum description length (MDL) principle. In particular, we consider that the design space of the penalty function is high-dimensional. In this situation,…

Machine Learning · Statistics 2018-04-27 Kohei Miyaguchi , Kenji Yamanishi

Inspired by several real-life applications in audio processing and medical image analysis, where the quantity of interest is generated by several sources to be accurately modeled and separated, as well as by recent advances in…

Numerical Analysis · Mathematics 2016-09-21 Markus Grasmair , Valeriya Naumova

Rank minimization (RM) is a wildly investigated task of finding solutions by exploiting low-rank structure of parameter matrices. Recently, solving RM problem by leveraging non-convex relaxations has received significant attention. It has…

Machine Learning · Computer Science 2018-09-17 Zaiyi Chen

Regularization methods improve the stability of ill-posed inverse problems by introducing some a priori characteristics for the solution such as smoothness or sharpness. In this contribution, we propose a multidimensional, scale-dependent…

Geophysics · Physics 2023-01-27 Wouter Deleersnyder , Benjamin Maveau , David Dudal , Thomas Hermans

We propose a loop optimization algorithm based on nuclear norm regularization for tensor network. The key ingredient of this scheme is to introduce a rank penalty term proposed in the context of data processing. Compared to standard…

Statistical Mechanics · Physics 2024-11-07 Kenji Homma , Tsuyoshi Okubo , Naoki Kawashima

This paper is concerned with a novel regularisation technique for solving linear ill-posed operator equations in Hilbert spaces from data that is corrupted by white noise. We combine convex penalty functionals with extreme-value statistics…

Statistics Theory · Mathematics 2012-04-03 Klaus Frick , Philipp Marnitz , Axel Munk

In this work, we investigate data fitting problems with random noises. A randomized progressive iterative regularization method is proposed. It works well for large-scale matrix computations and converges in expectation to the least-squares…

Numerical Analysis · Mathematics 2025-06-05 Dakang Cen , Wenlong Zhang , Junbin Zhong

The L1 norm regularized least squares method is often used for finding sparse approximate solutions and is widely used in 1-D signal restoration. Basis pursuit denoising (BPD) performs noise reduction in this way. However, the shortcoming…

Computer Vision and Pattern Recognition · Computer Science 2020-01-30 Nantheera Anantrasirichai , Rencheng Zheng , Ivan Selesnick , Alin Achim

For an ill-posed inverse problem, particularly with incomplete and limited measurement data, regularization is an essential tool for stabilizing the inverse problem. Among various forms of regularization, the lp penalty term provides a…

Numerical Analysis · Mathematics 2021-12-23 Jihun Han , Yoonsang Lee

In this work, we consider a constrained convex problem with linear inequalities and provide an inexact penalty re-formulation of the problem. The novelty is in the choice of the penalty functions, which are smooth and can induce a non-zero…

Optimization and Control · Mathematics 2020-05-04 Tatiana Tatarenko , Angelia Nedich
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