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A new method, based on the simulated annealing algorithm and aimed at the inverse problem in the analysis of intergalactic (interstellar) complex spectra of hydrogen and metal lines, is presented. We consider the process of line formation…

Astrophysics · Physics 2007-05-23 Sergei A. Levshakov , Irina I. Agafonova , Wilhelm H. Kegel

Inverse rendering methods have achieved remarkable performance in reconstructing high-fidelity 3D objects with disentangled geometries, materials, and environmental light. However, they still face huge challenges in reflective surface…

Computer Vision and Pattern Recognition · Computer Science 2024-11-22 Tengjie Zhu , Zhuo Chen , Jingnan Gao , Yichao Yan , Xiaokang Yang

The deduction from solar flare X-ray photon spectroscopic data of the energy dependent model-independent spectral index is considered as an inverse problem. Using the well developed regularization approach we analyze the energy dependency…

Astrophysics · Physics 2009-11-11 Eduard P. Kontar , Alexander L. MacKinnon

Observations of the Sun in the visible spectral range belong to standard measurements obtained by instruments both on the ground and in the space. Nowadays, both nearly continuous full-disc observations with medium resolution and dedicated…

Solar and Stellar Astrophysics · Physics 2020-06-30 Michal Švanda , Jan Jurčák , David Korda , Jana Kašparová

This paper describes the X-ray and gamma-ray imaging spectroscopy capabilities of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). It also outlines RHESSI's major scientific accomplishments during the 16 years of operations from…

Solar and Stellar Astrophysics · Physics 2023-04-05 Brian R. Dennis , Albert Y. Shih , Gordon J. Hurford , Pascal Saint-Hilaire

Next-generation ground-based solar observations require good image quality metrics for post-facto processing techniques. Based on the assumption that texture features in solar images are multi-fractal which can be extracted by a trained…

Instrumentation and Methods for Astrophysics · Physics 2019-10-09 Yi Huang , Peng Jia , Dongmei Cai , Bojun Cai

We compare the photometric accuracy of spectra and images in flares observed with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI)}spacecraft. We test the accuracy of the photometry by comparing the photon fluxes obtained in…

We develop and implement a compressive reconstruction method for tomographic recovery of refractive index distribution for weakly attenuating objects in a microfocus X-ray system. This is achieved through the development of a discretized…

This review aims to introduce the x-ray emission spectroscopy (XES) and resonant inelastic x-ray scattering (RIXS) techniques to the materials scientist working with magnetic semiconductors (e.g. semiconductors doped with 3d transition…

Materials Science · Physics 2014-01-20 Mauro Rovezzi , Pieter Glatzel

Quantitative and analytical analysis of modulation process of the collimator is a great challenge, and is also of great value to the design and development of Fourier transform imaging telescopes. The Hard X-ray Imager (HXI), as one of the…

Instrumentation and Methods for Astrophysics · Physics 2023-02-01 Xian-Kai Jiang , Jian Wu , Deng-Yi Chen , Yi-Ming Hu , Hao-Xiang Wang , Wei Liu , Zhe Zhang

The modern Doppler Imaging (DI) technique allows the reconstruction of different stellar surface structures based on accurate calculation of spectra of specific intensity. New applications like the mapping of the magnetic field vector put…

Astrophysics · Physics 2007-05-23 N. Piskunov

Radar Cross Section measurement data is often analyzed using Inverse Synthetic Aperture Radar images. This paper compares backprojection and iterative smooth reweighted $\ell_1$-minimization as methods to analyze radar cross section…

Signal Processing · Electrical Eng. & Systems 2025-08-15 Christer Larsson

Methods for 3D reconstruction such as Photometric stereo recover the shape and reflectance properties using multiple images of an object taken with variable lighting conditions from a fixed viewpoint. Photometric stereo assumes that a scene…

Computer Vision and Pattern Recognition · Computer Science 2018-11-07 Anish R. Khadka , Paolo Remagnino , Vasileios Argyriou

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

We propose a novel multivariate Monte Carlo method as an efficient and flexible approach to analyzing extended X-ray sources with the Reflection Grating Spectrometer (RGS) on XMM Newton. A multi-dimensional interpolation method is used to…

Astrophysics · Physics 2009-11-10 J. R. Peterson , J. G. Jernigan , S. M. Kahn

Susceptibility tensor imaging (STI) is an emerging magnetic resonance imaging technique that characterizes the anisotropic tissue magnetic susceptibility with a second-order tensor model. STI has the potential to provide information for…

Image and Video Processing · Electrical Eng. & Systems 2022-09-13 Zhenghan Fang , Kuo-Wei Lai , Peter van Zijl , Xu Li , Jeremias Sulam

For reconstruction of the spatial structure of many-component objects, it is proposed to use multi-radiography with detection of X-ray by combined detector arrays using detectors of ``scintillator-photodiode'' type. A theoretical model has…

Instrumentation and Detectors · Physics 2007-05-23 S. V. Naydenov , V. D. Ryzhikov , B. V. Grinyov , E. K. Lisetskaya , A. D. Opolonin , D. N. Kozin

We discuss multivariate Monte Carlo methods appropriate for X-ray dispersive spectrometers. Dispersive spectrometers have many advantages for high resolution spectroscopy in the X-ray band. Analysis of data from these instruments is…

Astrophysics · Physics 2007-05-23 J. R. Peterson , J. G. Jernigan , S. M. Kahn

Large aperture ground based solar telescopes allow the solar atmosphere to be resolved in unprecedented detail. However, observations are limited by Earths turbulent atmosphere, requiring post image corrections. Current reconstruction…

Solar and Stellar Astrophysics · Physics 2025-06-06 Christoph Schirninger , Robert Jarolim , Astrid M. Veronig , Christoph Kuckein

Coded aperture snapshot spectral imaging (CASSI) is a promising technique to capture the three-dimensional hyperspectral image (HSI) using a single coded two-dimensional (2D) measurement, in which algorithms are used to perform the inverse…

Image and Video Processing · Electrical Eng. & Systems 2021-01-01 Wei He , Naoto Yokoya , Xin Yuan