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We propose a stable and fast reconstruction technique for parallel-beam (PB) tomographic X-ray imaging, relying on the discrete pseudo-polar (PP) Radon transform. Our main contribution is a resampling method, based on modern sampling…

Numerical Analysis · Computer Science 2018-03-29 Shahar Tsiper , Yonina C. Eldar

This paper is concerned with a practical inverse problem of simultaneously reconstructing the surface heat flux and the thickness of a solid structure from the associated ultrasonic measurements. In a thermoacoustic coupling model, the…

Numerical Analysis · Mathematics 2020-12-01 Youjun Deng , Hongyu Liu , Xianchao Wang , Dong Wei , Liyan Zhu

Learned iterative reconstruction algorithms for inverse problems offer the flexibility to combine analytical knowledge about the problem with modules learned from data. This way, they achieve high reconstruction performance while ensuring…

Image and Video Processing · Electrical Eng. & Systems 2022-10-24 Mareike Thies , Fabian Wagner , Mingxuan Gu , Lukas Folle , Lina Felsner , Andreas Maier

We present a combined analysis of the X-ray emission of the Capella corona obtained with \textit{XMM-Newton} RGS, \textit{Chandra} HETGS, and LETGS. An improved atomic line database and a new differential emission measure (DEM)…

Astrophysics · Physics 2008-11-26 M. F. Gu , R. Gupta , J. R. Peterson , M. Sako , S. M. Kahn

A discrete tomography method has been developed that is able to reconstruct three-dimensional coronal mass ejection (CME) density structure. We test the method by producing synthetic coronagraph imagery for three events using the…

Solar tomography has progressed rapidly in recent years thanks to the development of robust algorithms and the availability of more powerful computers. It can today provide crucial insights in solving issues related to the line-of-sight…

Solar and Stellar Astrophysics · Physics 2015-05-27 Nicolas Barbey , Chloé Guennou , Frédéric Auchère

We reach a thermodynamic interpretation of CODET model and its prediction to electrons density and temperature grounded on the physics of hydro magnetism in global equilibrium. The thermodynamic interpretation finds consistency with the…

Solar and Stellar Astrophysics · Physics 2020-05-19 Daniel B. Berdichevsky , Jenny M. Rodríguez Gómez , Luis E. Vieira , Allison Dal Lago

Collimated beam ultrasound systems are a novel technology for imaging inside multi-layered structures such as geothermal wells. Such systems include a transmitter and multiple receivers to capture reflected signals. Common algorithms for…

Image and Video Processing · Electrical Eng. & Systems 2022-02-22 Abdulrahman Alanazi , Singanallur Venkatakrishnan , Hector Santos-Villalobos , Gregery Buzzard , Charles Bouman

We analyze the mathematical model of multiwave tomography with a variable speed with integrating measurements on planes tangent to a sphere surrounding the source. We prove sharp uniqueness and stability estimates with full and partial data…

Analysis of PDEs · Mathematics 2016-05-04 Plamen Stefanov , Yang Yang

Understanding the density structure of the solar corona is important for modeling both coronal heating and the solar wind. Direct measurements are difficult because of line-of-sight integration and possible unresolved structures. We present…

Solar and Stellar Astrophysics · Physics 2016-09-28 Michael Hahn , Daniel Wolf Savin

The use of Fourier methods in wave-front reconstruction can significantly reduce the computation time for large telescopes with a high number of degrees of freedom. However, Fourier algorithms for discrete data require a rectangular data…

Instrumentation and Methods for Astrophysics · Physics 2017-06-07 Charlotte Z. Bond , Carlos M. Correia , Jean-François Sauvage , Benoit Neichel , Thierry Fusco

Almost all known image reconstruction algorithms for photoacoustic and thermoacoustic tomography assume that the acoustic waves leave the region of interest after a finite time. This assumption is reasonable if the reflections from the…

Analysis of PDEs · Mathematics 2015-06-16 L. Kunyansky , B. Holman , B. T. Cox

The high dissipation of integrated circuits means serious problems for packaging and for the design of complex electronic systems. Another important area of research and development nowadays is the integration of sensors and micromechanical…

Materials Science · Physics 2007-09-13 L. Pohl , V. Szekely

In this paper, we presented an efficient algorithm to implement the regularization reconstruction of SPECT. Image reconstruction with priori assumptions is usually modeled as a constrained optimization problem. However, there is no…

Optimization and Control · Mathematics 2013-06-07 Shousheng Luo , Tie Zhou

In this work we develop and analyze an adaptive finite element method for efficiently solving electrical impedance tomography -- a severely ill-posed nonlinear inverse problem for recovering the conductivity from boundary voltage…

Numerical Analysis · Mathematics 2019-05-16 Bangti Jin , Yifeng Xu , Jun Zou

Gamma-ray astronomy from hundreds of GeV to PeV is confined to ground-based experiments that detect air showers induced by $\gamma$-rays entering Earth's atmosphere. While particle detector arrays feature huge detection areas, accurately…

Instrumentation and Methods for Astrophysics · Physics 2026-04-13 Markus Pirke , Youngwan Son , Jonas Glombitza , Martin Schneider , Ian James Watson , Christopher van Eldik

Ground-based solar observations enable unprecedented spatial, spectral, and temporal resolution of the lower solar atmosphere, yet Earths turbulent atmosphere imposes significant limitations, requiring advanced post-facto image…

Solar and Stellar Astrophysics · Physics 2026-03-06 Christoph Schirninger , Robert Jarolim , Astrid M. Veronig , Matthias Rempel , Friedrich Wöger

Magnetic loops are building blocks of the closed-field corona. While active region loops are readily seen in images taken at EUV and X-ray wavelengths, quiet Sun loops are seldom identifiable and therefore difficult to study on an…

Solar and Stellar Astrophysics · Physics 2015-06-05 Zhenguang Huang , Richard A. Frazin , Enrico Landi , Ward B. Manchester , Alberto M. Vásquez , Tamas I. Gombosi

The most popular method for determining coronal temperatures is the scale-height-method (shm). It is based on electron density profiles inferred from White Light (WL) brightness measurements of the corona during solar eclipses. This method…

Solar and Stellar Astrophysics · Physics 2012-01-19 J. F. Lemaire

The aim of electrical impedance tomography is to form an image of the conductivity distribution inside an unknown body using electric boundary measurements. The computation of the image from measurement data is a non-linear ill-posed…

Numerical Analysis · Mathematics 2011-09-28 Samuli Siltanen , Janne P. Tamminen