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We consider the problem of detecting the locations of targets in the far field by sending probing signals from an antenna array and recording the reflected echoes. Drawing on key concepts from the area of compressive sensing, we use an…

Information Theory · Computer Science 2013-04-25 Max Hügel , Holger Rauhut , Thomas Strohmer

Multiple scattering of polarised electromagnetic waves in diffusive media is investigated by means of radiative transfer theory. The method becomes exact in several situations of interest, such as a thick-slab experiment (slab thickness L…

Condensed Matter · Physics 2009-10-28 E. Amic , J. M. Luck , Th. M. Nieuwenhuizen

This paper presents a fast high-order method for the solution of two-dimensional problems of scattering by penetrable inhomogeneous media, with application to high-frequency configurations containing (possibly) discontinuous refractivities.…

Numerical Analysis · Mathematics 2023-07-31 Oscar P. Bruno , Ambuj Pandey

While scattered light conveys most of the information we perceive, scattering may also distort that information before it reaches our detectors. The problem is acute in many applications, such as in high-resolution microscopy of biological…

This is the second part in a series of two papers that concern with the quantitative analysis of the electromagnetic field enhancement and anomalous diffraction by a periodic array of subwavelength slits. In this part, we explore the…

Analysis of PDEs · Mathematics 2017-06-08 Junshan Lin , Hai Zhang

The scattering of waves in a complex medium is perturbed by polarizability changes or motion of embedded targets. These perturbations could serve as perfectly non-invasive guidestars for focusing on the targets. In this Letter, we…

Optics · Physics 2024-01-30 Jérôme Sol , Luc Le Magoarou , Philipp del Hougne

Optical focusing through/inside scattering media, like multimode fiber and biological tissues, has significant impact in biomedicine yet considered challenging due to strong scattering nature of light. Previously, promising progress has…

In the context of providing a mathematical framework for the propagation of ultrasound waves in a random multiscale medium, we consider the scattering of classical waves (modeled by a divergence form scalar Helmholtz equation) by a bounded…

Analysis of PDEs · Mathematics 2023-09-15 Josselin Garnier , Laure Giovangigli , Quentin Goepfert , Pierre Millien

In this investigation, we propose several algorithms to recover the location and intensity of a radiation source located in a simulated 250 m x 180 m block in an urban center based on synthetic measurements. Radioactive decay and detection…

Applications · Statistics 2016-07-05 Razvan Stefanescu , Kathleen Schmidt , Jason Hite , Ralph Smith , John Mattingly

In this paper, a linear model based on multiple measurement vectors model is proposed to formulate the inverse scattering problem of highly conductive objects at one single frequency. Considering the induced currents which are mostly…

Signal Processing · Electrical Eng. & Systems 2019-06-27 Shilong Sun , Bert Jan Kooij , Alexander G. Yarovoy

We introduce a new variational method for the numerical homogenization of divergence form elliptic, parabolic and hyperbolic equations with arbitrary rough ($L^\infty$) coefficients. Our method does not rely on concepts of ergodicity or…

Numerical Analysis · Mathematics 2019-02-20 Houman Owhadi , Lei Zhang , Leonid Berlyand

With the increasing use of ultrashort laser pulses and nanoscale-materials, one is regularly confronted to situations in which the properties of the media supporting propagation are not varying slowly with time (or space). Hence, the usual…

Other Condensed Matter · Physics 2009-11-10 Guillaume Petite , Alexander Shvartsburg

Conventional algorithms for sparse signal recovery and sparse representation rely on $l_1$-norm regularized variational methods. However, when applied to the reconstruction of $\textit{sparse images}$, i.e., images where only a few pixels…

Computer Vision and Pattern Recognition · Computer Science 2016-05-09 Sohil Shah , Tom Goldstein , Christoph Studer

Problems in differentiable rendering often involve optimizing scene parameters that cause motion in image space. The gradients for such parameters tend to be sparse, leading to poor convergence. While existing methods address this sparsity…

Graphics · Computer Science 2025-03-31 Ishit Mehta , Manmohan Chandraker , Ravi Ramamoorthi

Several approaches have been proposed to solve the spectral unmixing problem in hyperspectral image analysis. Among them the use of sparse regression techniques aims to characterize the abundances in pixels based on a large library of…

Image and Video Processing · Electrical Eng. & Systems 2021-02-12 L. C. Ayres , S. J. M. de Almeida , J. C. M. Bermudez , R. A. Borsoi

We present a framework for smooth optimization of explicitly regularized objectives for (structured) sparsity. These non-smooth and possibly non-convex problems typically rely on solvers tailored to specific models and regularizers. In…

Machine Learning · Computer Science 2026-04-09 Chris Kolb , Christian L. Müller , Bernd Bischl , David Rügamer

In-network distributed estimation of sparse parameter vectors via diffusion LMS strategies has been studied and investigated in recent years. In all the existing works, some convex regularization approach has been used at each node of the…

Machine Learning · Computer Science 2016-11-15 Bijit Kumar Das , Mrityunjoy Chakraborty , Jerónimo Arenas-García

Motivated by distributed machine learning settings such as Federated Learning, we consider the problem of fitting a statistical model across a distributed collection of heterogeneous data sets whose similarity structure is encoded by a…

Statistics Theory · Mathematics 2021-11-30 Dominic Richards , Sahand N. Negahban , Patrick Rebeschini

Embeddings provide compact representations of signals in order to perform efficient inference in a wide variety of tasks. In particular, random projections are common tools to construct Euclidean distance-preserving embeddings, while…

Data Structures and Algorithms · Computer Science 2019-09-05 Diego Valsesia , Sophie Marie Fosson , Chiara Ravazzi , Tiziano Bianchi , Enrico Magli

Persistent scatterer interferometry and Synthetic Aperture Radar (SAR) Tomography are powerful tools for the detection and time monitoring of persistent scatterers. They have been proven to be effective in urban scenarios, especially for…

Signal Processing · Electrical Eng. & Systems 2026-02-05 Pia Addabbo , Diego Reale , Antonio Pauciullo , Gianfranco Fornaro , Danilo Orlando