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Learned Sparse Retrieval (LSR) is an effective IR approach that exploits pre-trained language models for encoding text into a learned bag of words. Several efforts in the literature have shown that sparsity is key to enabling a good…

Information Retrieval · Computer Science 2025-05-06 Franco Maria Nardini , Thong Nguyen , Cosimo Rulli , Rossano Venturini , Andrew Yates

Diffusion models have become a leading paradigm for image super-resolution (SR), but existing methods struggle to guarantee both the high-frequency perceptual quality and the low-frequency structural fidelity of generated images. Although…

Computer Vision and Pattern Recognition · Computer Science 2026-04-14 Hexin Zhang , Dong Li , Jie Huang , Bingzhou Wang , Xueyang Fu , Zhengjun Zha

Wave equation techniques have been an integral part of geophysical imaging workflows to investigate the Earth's subsurface. Least-squares reverse time migration (LSRTM) is a linearized inversion problem that iteratively minimizes a misfit…

Computational Physics · Physics 2019-12-11 Janaki Vamaraju , Jeremy Vila , Mauricio Araya-Polo , Debanjan Datta , Mohamed Sidahmed , Mrinal Sen

Estimation of a precision matrix (i.e., inverse covariance matrix) is widely used to exploit conditional independence among continuous variables. The influence of abnormal observations is exacerbated in a high dimensional setting as the…

Methodology · Statistics 2021-05-17 Peng Tang , Huijing Jiang , Heeyoung Kim , Xinwei Deng

The classical iteratively reweighted least-squares (IRLS) algorithm aims to recover an unknown signal from linear measurements by performing a sequence of weighted least squares problems, where the weights are recursively updated at each…

Machine Learning · Statistics 2024-06-06 Chiraag Kaushik , Justin Romberg , Vidya Muthukumar

Adaptive optics (AO) systems and image reconstruction algorithms are indispensable tools when it comes to high-precision astrometry. In this paper, we analyze the potential of combining both techniques, i.e. by applying image reconstruction…

Instrumentation and Methods for Astrophysics · Physics 2019-03-13 Felix Bosco , Jörg-Uwe Pott , Rainer Schödel

Nowadays, the field computed tomography (CT) encompasses a large variety of settings, ranging from nanoscale to meter-sized objects imaged by different kinds of radiation in various acquisition modes. This experimental diversity challenges…

Numerical Analysis · Mathematics 2019-01-11 Simon Maretzke

We propose a variation on wavefield reconstruction inversion for seismic inversion, which takes advantage of randomized linear algebra as a way to overcome the typical limitations of conventional inversion techniques. Consequently, we can…

Numerical Analysis · Mathematics 2021-12-21 Gabrio Rizzuti , Tristan van Leeuwen

Determining the mass of stars is crucial both to improving stellar evolution theory and to characterising exoplanetary systems. Asteroseismology offers a promising way to estimate stellar mean density. When combined with accurate radii…

Solar and Stellar Astrophysics · Physics 2015-06-03 D. R. Reese , J. P. Marques , M. J. Goupil , M. J. Thompson , S. Deheuvels

Inverse medium scattering is an ill-posed, nonlinear wave-based imaging problem arising in medical imaging, remote sensing, and non-destructive testing. Machine learning (ML) methods offer increased inference speed and flexibility in…

Computational Physics · Physics 2025-12-12 Olivia Tsang , Owen Melia , Vasileios Charisopoulos , Jeremy Hoskins , Yuehaw Khoo , Rebecca Willett

We consider the problem of supervised learning with convex loss functions and propose a new form of iterative regularization based on the subgradient method. Unlike other regularization approaches, in iterative regularization no constraint…

Machine Learning · Statistics 2015-04-02 Junhong Lin , Lorenzo Rosasco , Ding-Xuan Zhou

Interferometric Synthetic Aperture Radar (InSAR) Imaging methods are usually based on algorithms of match-filtering type, without considering the scene's characteristic, which causes limited imaging quality. Besides, post-processing steps…

Signal Processing · Electrical Eng. & Systems 2022-10-07 Xu Zhan , Xiaoling Zhang , Shunjun Wei , Jun Shi

In this article we study the problem of recovering the unknown solution of a linear ill-posed problem, via iterative regularization methods. We review the problem of projection-regularization from a statistical point of view. A basic…

Statistics Theory · Mathematics 2007-06-13 Ana K. Fermin , Carenne Ludena

We propose a new algorithm for the problem of recovering data that adheres to multiple, heterogeneous low-dimensional structures from linear observations. Focusing on data matrices that are simultaneously row-sparse and low-rank, we propose…

Machine Learning · Computer Science 2024-01-19 Christian Kümmerle , Johannes Maly

We present a detailed analysis of a new, iterative density reconstruction algorithm. This algorithm uses a decreasing smoothing scale to better reconstruct the density field in Lagrangian space. We implement this algorithm to run on the…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-19 Xinyi Chen , Nikhil Padmanabhan

This study concentrates on advancing mathematical and computational methodology for radar tomography imaging in which the unknown volumetric velocity distribution of a wave within a bounded domain is to be reconstructed. Our goal is to…

Instrumentation and Methods for Astrophysics · Physics 2018-04-04 Mika Takala , Defne Us , Sampsa Pursiainen

Helioseismic inversions, carried out for several years on various ground-based and spatial observations, have shown that the solar rotation rate presents two principal regimes: a quasi-rigid rotation in the radiative interior and a…

Astrophysics · Physics 2007-05-23 T. Corbard , G. Berthomieu , J. Provost , P. Morel

Seismic waves are the most sensitive probe of the Earth's interior we have. With the dense data sets available in exploration, images of subsurface structures can be obtained through processes such as migration. Unfortunately, relating…

Geophysics · Physics 2009-05-05 R. B. Schlottmann

In many applications of tomography, the acquired projections are either limited in number or contain a significant amount of noise. In these cases, standard reconstruction methods tend to produce artifacts that can make further analysis…

Numerical Analysis · Mathematics 2016-04-11 D. M. Pelt , K. J. Batenburg

An approach is introduced for the non-parametric reconstruction of the statistical properties of penetrable, isotropic randomly rough surfaces from in-plane, co-polarized light scattering data. Starting from expressions within the Kirchhoff…

Optics · Physics 2021-10-13 Verónica P. Simonsen , Dick Bedeaux , Ingve Simonsen