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This paper investigates the possibility of improving radio interferometric images using an algorithm inspired by an optical method known as "lucky imaging", which would give more weight to the best-calibrated visibilities used to make a…

Instrumentation and Methods for Astrophysics · Physics 2018-07-18 Etienne Bonnassieux , Cyril Tasse , Oleg Smirnov , Philippe Zarka

This work deals with an inverse source problem for the biharmonic wave equation. A two-stage numerical method is proposed to identify the unknown source from the multi-frequency phaseless data. In the first stage, we introduce some…

Numerical Analysis · Mathematics 2024-01-08 Yan Chang , Yukun Guo , Yue Zhao

Phase diversity is a widefield aberration correction method that uses multiple images to estimate the phase aberration at the pupil plane of an imaging system by solving an optimization problem. This estimated aberration can then be used to…

Image and Video Processing · Electrical Eng. & Systems 2023-08-03 Nikolaj Reiser , Min Guo , Hari Shroff , Patrick J. La Riviere

Wavefront sensing involves estimating the phase and intensity of light, enabling a wide range of imaging applications, from adaptive optics and astronomy to biomedical imaging. Since conventional image sensors can only measure the spatial…

Image and Video Processing · Electrical Eng. & Systems 2026-04-07 Nebiyou Yismaw , Vishwanath Saragadam , Aswin C. Sankaranarayanan , M. Salman Asif

Context. Very Long Baseline Interferometry (VLBI) data are extremely sensitive to the phase stability of the VLBI array. This is especially important when we reach {\mu}Jy r.m.s. sensitivities. Calibration using standard phase referencing…

Instrumentation and Methods for Astrophysics · Physics 2016-02-24 Jack F. Radcliffe , Michael A. Garrett , Rob J. Beswick , Tom W. B. Muxlow , Peter Barthel , Adam T. Deller , Enno Middelberg

The abundance of data produced daily from large variety of sources has boosted the need of novel approaches on causal inference analysis from observational data. Observational data often contain noisy or missing entries. Moreover, causal…

Methodology · Statistics 2017-03-14 Fani Tsapeli , Peter Tino , Mirco Musolesi

We introduce a simple, intuitive and yet powerful algorithm for clustering analysis. This algorithm is an iterative process on the sample space, which arises as an extension of the iteratively generated correlation matrices. It allows for…

Methodology · Statistics 2015-08-21 Shang-Ying Shiu , Ting-Li Chen

Current cosmological analyses which use Type Ia supernova (SN Ia) observations combine SN samples to expand the redshift range beyond that of a single sample and increase the overall sample size. The inhomogeneous photometric calibration…

This paper introduces an amendment to radio interferometric calibration of sources below the noise level. The main idea is to employ the information of the stronger sources' measured signals as a plug-in criterion to solve for the weaker…

Instrumentation and Methods for Astrophysics · Physics 2016-11-15 Sanaz Kazemi , Sarod Yatawatta , Saleem Zaroubi

Long duration noisy-looking waveforms such as those obtained in randomly multiply scattering and reverberant media are complex; they resist direct interpretation. Nevertheless, such waveforms are sensitive to small changes in the source of…

Geophysics · Physics 2015-05-27 Richard L Weaver , Céline Hadziioannou , Eric Larose , Michel Campillo

Interferometric calibration always yields non unique solutions. It is therefore essential to remove these ambiguities before the solutions could be used in any further modeling of the sky, the instrument or propagation effects such as the…

Instrumentation and Methods for Astrophysics · Physics 2013-07-19 Sarod Yatawatta

The phase retrieval from multi-frequency intensity (power) observations is considered. The object to be reconstructed is complex-valued. A novel algorithm is presented that accomplishes both the object phase (absolute phase) retrieval and…

Signal Processing · Electrical Eng. & Systems 2018-02-07 Vladimir Katkovnik , Karen Egiazarian

Phase retrieval consists in the recovery of an unknown signal from phaseless measurements of its usually complex-valued Fourier transform. Without further assumptions, this problem is notorious to be severe ill posed such that the recovery…

Information Theory · Computer Science 2023-01-19 Robert Beinert , Saghar Rezaei

Radio interferometric gain calibration can be biased by incomplete sky models and radio frequency interference, resulting in calibration artefacts that can restrict the dynamic range of the resulting images. It has been suggested that…

Instrumentation and Methods for Astrophysics · Physics 2019-10-21 Ulrich Armel Mbou Sob , Hertzog Landman Bester , Oleg Smirnov , Jonathan Kenyon , Trienko Grobler

Interferometric visibilities, reflecting the complex correlations between signals recorded at antennas in an interferometric array, carry information about the angular structure of a distant source. While unknown antenna gains in both…

Instrumentation and Methods for Astrophysics · Physics 2020-05-04 Lindy Blackburn , Dominic W. Pesce , Michael D. Johnson , Maciek Wielgus , Andrew A. Chael , Pierre Christian , Sheperd S. Doeleman

Fourier ptychographic microscopy is a computational imaging technique that provides quantitative phase information and high resolution over a large field-of-view. Although the technique presents numerous advantages over conventional…

Optics · Physics 2021-09-16 Eric Li , Stuart Sherwin , Gautam Gunjala , Laura Waller

In many areas of imaging science, it is difficult to measure the phase of linear measurements. As such, one often wishes to reconstruct a signal from intensity measurements, that is, perform phase retrieval. In this paper, we provide a…

Information Theory · Computer Science 2013-09-13 Boris Alexeev , Afonso S. Bandeira , Matthew Fickus , Dustin G. Mixon

We consider the problem of analyzing the structure of spectroscopic cubes using unsupervised machine learning techniques. We propose representing the target's signal as a homogeneous set of volumes through an iterative algorithm that…

Instrumentation and Methods for Astrophysics · Physics 2018-06-15 Mauricio Araya , Marcelo Mendoza , Mauricio Solar , Diego Mardones , Amelia Bayo

This article is devoted to the detection of parameters in anomalous diffusion from a single passive measurement. More precisely, we consider the simultaneous identification of coefficients as well as a time-dependent source term appearing…

Analysis of PDEs · Mathematics 2026-03-10 Maolin Deng , Ali Feizmohammadi , Bangti Jin , Yavar Kian

Current optical interferometers are affected by unknown turbulent phases on each telescope. In the field of radio-interferometry, the self-calibration technique is a powerful tool to process interferometric data with missing phase…

Optics · Physics 2009-11-13 Serge Meimon , Laurent M. Mugnier , Guy Le Besnerais