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In this paper, we deal with nonparametric regression for circular data, meaning that observations are represented by points lying on the unit circle. We propose a kernel estimation procedure with data-driven selection of the bandwidth…

Statistics Theory · Mathematics 2023-07-03 Tien Dat Nguyen , Thanh Mai Pham Ngoc , Vincent Rivoirard

Determining the physical parameters of pulsating variable stars such as RR Lyrae is essential for understanding their internal structure, pulsation mechanisms, and evolutionary state. In this study, we present a machine learning framework…

Solar and Stellar Astrophysics · Physics 2025-07-08 Nitesh Kumar , Harinder P. Singh , Oleg Malkov , Santosh Joshi , Kefeng Tan , Philippe Prugniel , Anupam Bhardwaj

The throughout knowledge of a X-ray beam spectrum is mandatory to assess the quality of its source device. Since the techniques to directly measurement such spectra are expensive and laborious, the X-ray spectrum reconstruction using…

Computational Physics · Physics 2014-11-12 Olavo Henrique Menin , Alexandre Souto Martinez , Alessandro Martins da Costa

This paper presents a parametric solution to piecewise linear regression through the Adaptive Block Gradient Descent (ABGD) algorithm. The heart of the method is the parametrization of piecewise linear functions as the difference of…

Machine Learning · Statistics 2026-05-11 Haitham Kanj , Kiryung Lee

The X-ray emission from accreting black hole (BH) systems displays strong variability. Short reverberation lags are expected between the primary hard X-ray continuum and the reprocessed disc emission. These lags depend on light-travel…

High Energy Astrophysical Phenomena · Physics 2019-05-15 B. De Marco , G. Ponti

We introduce a continuous global optimization method to the field of surface reconstruction from discrete noisy cloud of points with weak information on orientation. The proposed method uses an energy functional combining flux-based…

Graphics · Computer Science 2017-08-01 Rongjiang Pan , Vaclav Skala

Probing properties of neutron stars from photometric observations of these objects helps us answer crucial questions at the forefront of multi-messenger astronomy, such as, what is behavior of highest density matter in extreme environments…

High Energy Astrophysical Phenomena · Physics 2025-10-22 Abu Bucker Siddik , Diane Oyen , Soumi De , Greg Olmschenk , Constantinos Kalapotharakos

We devise a theory of x-ray absorption by symmetric-top molecules which are aligned by an intense optical laser. Initially, the density matrix of the system is composed of the electronic ground state of the molecules and a thermal ensemble…

Chemical Physics · Physics 2008-02-23 Christian Buth , Robin Santra

The advent of new time domain surveys and the imminent increase in astronomical data expose the shortcomings in traditional time series analysis (such as power spectra analysis) in characterising the abundantly varied, complex and…

Astrophysics of Galaxies · Physics 2020-07-22 R. A. Phillipson , P. T. Boyd , A. P. Smale , M. S. Vogeley

Atomic norm methods have recently been proposed for spectral super-resolution with flexibility in dealing with missing data and miscellaneous noises. A notorious drawback of these convex optimization methods however is their lower…

Signal Processing · Electrical Eng. & Systems 2022-11-29 Zai Yang , Yi-Lin Mo , Gongguo Tang , Zongben Xu

We present an efficient method for joint optimization of topology, materials and lighting from multi-view image observations. Unlike recent multi-view reconstruction approaches, which typically produce entangled 3D representations encoded…

Computer Vision and Pattern Recognition · Computer Science 2023-04-12 Jacob Munkberg , Jon Hasselgren , Tianchang Shen , Jun Gao , Wenzheng Chen , Alex Evans , Thomas Müller , Sanja Fidler

We present new measurements of the evolution of the X-ray luminosity functions (XLFs) of unabsorbed and absorbed Active Galactic Nuclei (AGNs) out to z~5. We construct samples containing 2957 sources detected at hard (2-7 keV) X-ray…

High Energy Astrophysical Phenomena · Physics 2015-05-11 James Aird , Alison L. Coil , Antonis Georgakakis , Kirpal Nandra , Guillermo Barro , Pablo G. Perez-Gonzalez

We propose a compressive sensing algorithm that exploits geometric properties of images to recover images of high quality from few measurements. The image reconstruction is done by iterating the two following steps: 1) estimation of normal…

Computer Vision and Pattern Recognition · Computer Science 2015-06-11 Virginia Estellers , Jean-Philippe Thiran , Xavier Bresson

A two-dimensional tomographic problem is studied. The target is assumed to be a homogeneous object bounded by a smooth curve. A Non Uniform Rational Basis Splines (NURBS) curve is used as computational representation of the boundary. This…

Numerical Analysis · Mathematics 2017-08-08 Heikki Haario , Aki Kallonen , Marko Laine , Esa Niemi , Zenith Purisha , Samuli Siltanen

In this paper, we study regression problems over a separable Hilbert space with the square loss, covering non-parametric regression over a reproducing kernel Hilbert space. We investigate a class of spectral/regularized algorithms,…

Machine Learning · Statistics 2022-07-18 Junhong Lin , Alessandro Rudi , Lorenzo Rosasco , Volkan Cevher

In this work, we propose a novel ensemble of recurrent neural networks (RNNs) that considers the multiband and non-uniform cadence without having to compute complex features. Our proposed model consists of an ensemble of RNNs, which do not…

Instrumentation and Methods for Astrophysics · Physics 2025-01-27 I. Becker , P. Protopapas , M. Catelan , K. Pichara

The synthesis model for the cosmic X-ray background (XRB) -based on the integrated emission of Active Galactic Nuclei (AGNs)- is complemented with new observational results. We adopt the most recent estimates of the AGN X-ray luminosity…

Astrophysics · Physics 2007-05-23 R. Gilli , G. Risaliti , M. Salvati

Over the past decade, a significant amount of effort has been put into investigating the ultraviolet (UV) and optical variability of active galactic nuclei (AGNs). Comprehensive studies of intensive multi-wavelength monitoring and surveys…

High Energy Astrophysical Phenomena · Physics 2025-09-04 M. Papoutsis , I. E. Papadakis , C. Panagiotou , E. Kammoun , M. Dovciak

Anisotropic diffusion filtering for signal smoothing as a low-pass filter has the advantage of the edge-preserving, i.e., it does not affect the edges that contain more critical data than the other parts of the signal. In this paper, we…

Signal Processing · Electrical Eng. & Systems 2022-02-02 Arsham Gholamzadeh Khoee , Kimia Mohammadi Mohammadi , Mostafa Jani , Kourosh Parand

Quantum optimization methods use a continuous degree-of-freedom of quantum states to heuristically solve combinatorial problems, such as the MAX-CUT problem, which can be attributed to various NP-hard combinatorial problems. This paper…

Quantum Physics · Physics 2025-01-15 Ruho Kondo , Yuki Sato , Rudy Raymond , Naoki Yamamoto