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We introduce a novel method, called Dispersion Entropy for Graph Signals, $DE_G$, as a powerful tool for analysing the irregularity of signals defined on graphs. We demonstrate the effectiveness of $DE_G$ in detecting changes in the…

Combinatorics · Mathematics 2023-04-03 John Stewart Fabila-Carrasco , Chao Tan , Javier Escudero

We address the problem of detecting non-stationary effects in time series (in particular fractal time series) by means of the Diffusion Entropy Method (DEM). This means that the experimental sequence under study, of size $N$, is explored…

Statistical Mechanics · Physics 2016-11-23 P. Allegrini , P. Grigolini , P. Hamilton , L. Palatella , G. Raffaelli , M. Virgilio

Aims. An attempt to classify gamma-ray bursts (GRBs) with a low level of supervision using the state-of-the-start approaches stemming from graph theory was undertaken. Methods. Graph-based classification methods, relying on different…

High Energy Astrophysical Phenomena · Physics 2021-09-28 Mariusz Tarnopolski

It is usual, in gamma-ray burst (GRB) studies, to compare the average properties of bright and faint GRBs, with the assumption that brightness classes reflect distance classes. When brightness is intented to reflect the distance to the…

Astrophysics · Physics 2008-02-03 J-L. Atteia

The aim of this paper is to shed light on the analysis of non-stationary time series by means of the method of diffusion entropy. For this purpose, we first study the case when infinitely many time series, as different realizations of the…

Statistical Mechanics · Physics 2007-05-23 M. Virgilio , P. Grigolini

Crosscorrelation of the outputs of two Gravitational Wave (GW) detectors has recently been proposed [1] as a method for detecting statistical association between GWs and Gamma Ray Bursts (GRBs). Unfortunately, the method can be effectively…

Astrophysics · Physics 2009-11-07 G. Modestino , A. Moleti

The sky distribution of Gamma-Ray Bursts (GRBs) has been intensively studied by various groups for more than two decades. Most of these studies test the isotropy of GRBs based on their sky number density distribution. In this work we…

High Energy Astrophysical Phenomena · Physics 2017-12-25 Jakub Ripa , Arman Shafieloo

The statistical tests - done by the authors - are surveyed, which verify the null-hypothesis of the intrinsic randomness in the angular distribution of gamma-ray bursts collected at BATSE Catalog. The tests use the counts-in-cells method,…

High Energy Astrophysical Phenomena · Physics 2015-05-14 A. Meszaros , Z. Bagoly , L. G. Balazs , I. Horvath , R. Vavrek

We have laid down the formalism and techniques necessary for computing the multipole components in a spherical harmonic expansion for bursting sources given any specific power spectrum of density perturbations. Using this formalism we have…

Astrophysics · Physics 2009-10-28 Tsvi Piran , Anupam Singh

Gamma ray burst (GRB) time series is a non-stationary time series with all its statistical properties varying with time. Considering that each GRB is a different manifestation of the same stochastic process we studied the time dependent as…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Nilay Bhatt , Subir Bhattacharyya

The entropy computation of Gaussian mixture distributions with a large number of components has a prohibitive computational complexity. In this paper, we propose a novel approach exploiting the sphere decoding concept to bound and…

Information Theory · Computer Science 2015-10-28 Su Min Kim , Tan Tai Do , Tobias J. Oechtering , Gunnar Peters

Graph spectral techniques for measuring graph similarity, or for learning the cluster number, require kernel smoothing. The choice of kernel function and bandwidth are typically chosen in an ad-hoc manner and heavily affect the resulting…

Machine Learning · Statistics 2019-12-20 Diego Granziol , Robin Ru , Stefan Zohren , Xiaowen Dong , Michael Osborne , Stephen Roberts

Clustering methods are an important tool to enumerate and describe the different coherent kinds of Gamma Ray Bursts (GRBs). But their performance can be affected by a number of factors such as the choice of clustering algorithm and inherent…

High Energy Astrophysical Phenomena · Physics 2017-06-13 Souradeep Chattopadhyay , Ranjan Maitra

Gamma-ray bursts (GRBs) are spectacularly energetic events, with the potential to inform on the early universe and its evolution, once their redshifts are known. Unfortunately, determining redshifts is a painstaking procedure requiring…

NMR is a tool of choice for the measure of diffusion coefficients of species in solution. The DOSY experiment, a 2D implementation of this measure, has proven to be particularly useful for the study of complex mixtures, molecular…

Data Analysis, Statistics and Probability · Physics 2017-04-12 Afef Cherni , Emilie Chouzenoux , Marc-André Delsuc

The cosmological principle, asserting large-scale homogeneity and isotropy, underpins the standard model of cosmology. Testing its validity using independent astronomical probes remains crucial for understanding the global structure of the…

High Energy Astrophysical Phenomena · Physics 2026-02-13 Debosi Mondal , Biswajit Pandey , Amit Mondal

This paper deals with the problem of outliers in high frequency observation data from diffusion processes. Robust estimation methods are needed because the inclusion of outliers can lead to incorrect statistical inference even in the…

Methodology · Statistics 2026-03-06 Tomoyuki Nakagawa , Yusuke Shimizu

A gravitationally lensed gamma-ray burst (GRB) would appear as multiple bursts with identical light curves, separated in time and differing only by the scaling of their amplitudes. However, noise may make them difficult to identify as…

Astrophysics · Physics 2009-10-22 M. A. Nowak , S. A. Grossman

Gamma-ray bursts are a complex, non-linear system that evolves very rapidly through stages of vastly different conditions. They evolve from scales of few hundred kilometers where they are very dense and hot to cold and tenuous on scales of…

High Energy Astrophysical Phenomena · Physics 2015-04-10 Davide Lazzati , Brian J. Morsony , Diego López-Cámara

Gamma-ray bursts (GRBs) are challenging to identify due to their transient nature, complex temporal profiles, and limited observational datasets. We address this with a one-dimensional convolutional neural network integrated with an…

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