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Stellarator optimization is a multi-objective, non-convex problem characterized by a complex objective landscape containing many local minima. The solution resulting from a single optimization is highly sensitive to factors such as the…

We designed and constructed a special instrument to enable the determination of the stellar's spin orientation. The Differential image rotator for Stellar Spin Orientation, DeSSpOt, allows the simultaneous observations of two anti-parallel…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 Anna-Lea Lesage , Magnus Schneide , Günter Wiedemann

We explore the sensitivity of several core-level spectroscopic methods to the underlying atomistic structure by using the water molecule as our test system. We first define a metric that measures the magnitude of spectral change as a…

Chemical Physics · Physics 2022-06-22 Johannes Niskanen , Anton Vladyka , Joonas Niemi , Christoph J. Sahle

The speckle noise inherent in Synthetic Aperture Radar (SAR) imagery significantly degrades image quality and complicates subsequent analysis. Given that SAR speckle is multiplicative and Gamma-distributed, effectively despeckling SAR…

Image and Video Processing · Electrical Eng. & Systems 2026-01-22 Junhyuk Heo

Principal Component Analysis (PCA) has been widely used for dimensionality reduction and feature extraction. Robust PCA (RPCA), under different robust distance metrics, such as l1-norm and l2, p-norm, can deal with noise or outliers to some…

Machine Learning · Computer Science 2021-06-29 Zhao Kang , Hongfei Liu , Jiangxin Li , Xiaofeng Zhu , Ling Tian

We propose a new smoothing method for obtaining surface densities from discrete particle positions from numerical simulations. This is an essential step for many applications in gravitational lensing. This method is based on the ``scatter''…

Astrophysics · Physics 2011-02-11 Guo-Liang Li , S. Mao , Y. P. Jing , X. Kang , M. Bartelmann

Aims. We provide an easy-to-use full-spectrum fitting package and explore its applications to (i) the determination of the stellar atmospheric parameters and (ii) the study of the history of stellar populations. Methods. We developed ULySS,…

Instrumentation and Methods for Astrophysics · Physics 2015-05-13 Mina Koleva , Philippe Prugniel , Antoine Bouchard , Yue Wu

We present an open source software package SpectroLab a Matlab-based tool developed in 2018 for the analysis of spectroscopic data. In this package, there are tools for derivative analysis, stacked energy contours, stacked plots for theory,…

Materials Science · Physics 2022-03-15 Christopher Sims

This paper presents a despeckling method for Sentinel-1 GRD images based on the recently proposed framework "SAR2SAR": a self-supervised training strategy. Training the deep neural network on collections of Sentinel 1 GRD images leads to a…

Image and Video Processing · Electrical Eng. & Systems 2021-10-28 Nicolas Gasnier , Emanuele Dalsasso , Loïc Denis , Florence Tupin

Information extraction from synthetic aperture radar (SAR) images is heavily impaired by speckle noise, hence despeckling is a crucial preliminary step in scene analysis algorithms. The recent success of deep learning envisions a new…

Image and Video Processing · Electrical Eng. & Systems 2020-07-07 Andrea Bordone Molini , Diego Valsesia , Giulia Fracastoro , Enrico Magli

The recent launch of the Kepler space telescope brings the opportunity to study oscillations systematically in large numbers of solar-like stars. In the framework of the asteroFLAG project, we have developed an automated pipeline to…

Sparse Principal Component Analysis (SPCA) is an important technique for high-dimensional data analysis, improving interpretability by imposing sparsity on principal components. However, existing methods often fail to simultaneously…

Machine Learning · Computer Science 2026-03-03 Difei Cheng , Qiao Hu

In recent years, dedicated extreme-precision radial velocity (EPRV) spectrographs have produced vast quantities of high-resolution, high-signal-to-noise time-series spectra for bright stars. These data contain valuable information for the…

Instrumentation and Methods for Astrophysics · Physics 2019-10-09 Megan Bedell , David W. Hogg , Daniel Foreman-Mackey , Benjamin T. Montet , Rodrigo Luger

Speckle suppression in synthetic aperture radar (SAR) images is a key processing step which continues to be a research topic. A wide variety of methods, using either spatially-based approaches or transform-based strategies, have been…

Computer Vision and Pattern Recognition · Computer Science 2024-08-30 Alejandro Mestre-Quereda , Juan M. Lopez-Sanchez

Aims. We present simulations of the perfomances of the future SPHERE IFS instrument designed for imaging extrasolar planets in the near infrared (Y, J, and H bands). Methods. We used the IDL package code for adaptive optics simulation…

Instrumentation and Methods for Astrophysics · Physics 2018-12-05 D. Mesa , R. Gratton , A. Berton , J. Antichi , C. Verinaud , A. Boccaletti , M. Kasper , R. U. Claudi , S. Desidera , E. Giro , J. -L. Beuzit , K. Dohlen , M. Feldt , D. Mouillet , G. Chauvin , A. Vigan

We present an algorithm that uses the distribution of photon arrival times to distinguish speckles from incoherent sources, like planets and disks, in high contrast images. Using simulated data, we show that our approach can overcome the…

Instrumentation and Methods for Astrophysics · Physics 2019-10-09 Alex B. Walter , Clinton Bockstiegel , Timothy D. Brandt , Benjamin A. Mazin

Many complex systems can be reduced to their key components through spectrally decomposing matrices that capture their dynamics. These matrices can in turn be constructed from data, often by least-squares fitting: examples of algorithms to…

Numerical Analysis · Mathematics 2026-05-18 Caroline Wormell

The study of astronomical phenomena through ground-based observations is always challenged by the distorting effects of Earth's atmosphere. Traditional methods of post-facto image correction, essential for correcting these distortions,…

Instrumentation and Methods for Astrophysics · Physics 2024-08-14 A. Asensio Ramos

SMART is a software package written in IDL to reduce and analyze Spitzer data from all four modules of the Infrared Spectrograph, including the peak-up arrays. The software is designed to make full use of the ancillary files generated in…

This paper tackles the problem of motion deblurring of dynamic scenes. Although end-to-end fully convolutional designs have recently advanced the state-of-the-art in non-uniform motion deblurring, their performance-complexity trade-off is…

Computer Vision and Pattern Recognition · Computer Science 2024-02-12 Maitreya Suin , Kuldeep Purohit , A. N. Rajagopalan