scholarly journals Detecting Criticality by Exploring the Acoustic Activity in Terms of the “Natural-Time” Concept

2021 ◽  
Vol 12 (1) ◽  
pp. 231
Author(s):  
Andronikos Loukidis ◽  
Dimos Triantis ◽  
Ilias Stavrakas ◽  
Ermioni D. Pasiou ◽  
Stavros K. Kourkoulis
Keyword(s):  
Power Law ◽  
Time Domain ◽  
Temporal Evolution ◽  
Critical Stage ◽  
Acoustic Activity ◽  
Natural Time ◽  
Self Consistent ◽  
Impending Fracture

The acoustic activity developed in marble specimens under various loading schemes is explored in terms of the recently introduced F-function. The novelty of the study is that instead of describing the temporal evolution of the F-function in terms of conventional time, the Natural Time concept is employed. Although completely different geometries and loading schemes were considered, the evolution of the F-function in the Natural Time domain exhibits a self-consistent motive: its values increase progressively with fluctuations of varying intensity, however, while the fracture is approaching, a power law appears to systematically govern the response of the specimen/structure loaded. The exponent of this law, somehow corresponding to the intensity of the acoustic activity within the loaded complex, varies within broad limits. The onset of validity of the power law designates that the system has entered into its critical stage, namely that of impending fracture, providing a useful pre-failure signal.

scholarly journals Collisional Evolution of Galaxy Clusters: Fokker–Planck and N-body models

2003 ◽  
Vol 208 ◽  
pp. 449-450
Author(s):  
Koji Takahashi ◽  
Tomohiro Sensui ◽  
Yoko Funato ◽  
Junichiro Makino
Keyword(s):  
Power Law ◽  
Dynamical Evolution ◽  
Cluster Center ◽  
Combined Effects ◽  
Clusters Of Galaxies ◽  
Relative Importance ◽  
Self Consistent ◽  
The Common ◽  
Good Agreement ◽  
Fokker Planck

We investigate the dynamical evolution of clusters of galaxies in virial equilibrium by using Fokker–Planck models and self-consistent N-body models. In particular we focus on the growth of the common halos and the development of the central density cusps in the clusters. We find good agreement between the Fokker–Planck and N-body models. At the cluster center the cusp approximated by a power law, ρ(r) ∝ r-α (α ∼ 1), develops. We conclude that this shallow cusp results from the combined effects of two-body relaxation and tidal stripping. The cusp steepness α weakly depends on the relative importance of tidal stripping.

scholarly journals Two optical emission components with different variability in V404 Cygni

2016 ◽  
Vol 12 (S324) ◽  
pp. 43-44
Author(s):  
Yutaro Tachibana ◽  
Taketoshi Yoshii ◽  
Nobuyuki Kawai
Keyword(s):  
Spectral Index ◽  
Power Law ◽  
Time Domain ◽  
Optical Emission ◽  
Time Domain Analysis ◽  
Blackbody Radiation ◽  
Light Curves ◽  
Variable Component ◽  
Single Temperature ◽  
The Time Domain

AbstractV404 Cygni went into an outburst again on June 15, 2015 after 26 years of quietness. Soon after the notifications, we started intense optical observation campaign of this source. The spectral index between RC and IC-band was stable over the outburst, whereas that between g′ and RC-band varied violently. With the time domain analysis of the multi-color optical light curves, we successfully decomposed optical variations into three components: highly-variable component (HVC), little-variable component (LVC). The loci of the LVC in the color-color diagram is consistent with that of a single temperature blackbody radiation or a multi-color blackbody radiation from a standard accretion disk, while those of the HVC trace that of power-law spectra.

scholarly journals Entropy in the natural time domain

2004 ◽  
Vol 70 (1) ◽  
Author(s):  
P. A. Varotsos ◽  
N. V. Sarlis ◽  
E. S. Skordas ◽  
M. S. Lazaridou
Keyword(s):  
Time Domain ◽  
Natural Time

scholarly journals Scaling analysis of COVID-19 spreading based on Belgian hospitalization data

2020 ◽  
Author(s):  
Bart Smeets ◽  
Rodrigo Watté ◽  
Herman Ramon
Keyword(s):  
Power Law ◽  
Temporal Evolution ◽  
Small World ◽  
Model Fit ◽  
Scaling Analysis ◽  
Reproduction Rate ◽  
Small World Network ◽  
Number Of Patients ◽  
Power Law Exponent ◽  
Kinetics Of

AbstractWe analyze the temporal evolution of accumulated hospitalization cases due to COVID-19 in Belgium. The increase of hospitalization cases is consistent with an initial exponential phase, and a subsequent power law growth. For the latter, we estimate a power law exponent of ≈ 2.2, which is consistent with growth kinetics of COVID-19 in China and indicative of the underlying small world network structure of the epidemic. Finally, we fit an SIR-X model to the experimental data and estimate the effect of containment policies in comparison to their effect in China. This model suggests that the base reproduction rate has been significantly reduced, but that the number of susceptible individuals that is isolated from infection is very small. Based on the SIR-X model fit, we analyze the COVID-19 mortality and the number of patients requiring ICU treatment over time.

scholarly journals Give Me a Few Hours: Exploring Short Timescales in Rubin Observatory Cadence Simulations

2022 ◽  
Vol 258 (1) ◽  
pp. 13
Author(s):  
Eric C. Bellm ◽  
Colin J. Burke ◽  
Michael W. Coughlin ◽  
Igor Andreoni ◽  
Claudia M. Raiteri ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Time Domain ◽  
Temporal Evolution ◽  
Transient Behavior ◽  
Wide Range ◽  
Pair Separation ◽  
Astrophysical Phenomena

Abstract The limiting temporal resolution of a time-domain survey in detecting transient behavior is set by the time between observations of the same sky area. We analyze the distribution of visit separations for a range of Vera C. Rubin Observatory cadence simulations. Simulations from families v1.5–v1.7.1 are strongly peaked at the 22 minute visit pair separation and provide effectively no constraint on temporal evolution within the night. This choice will necessarily prevent Rubin from discovering a wide range of astrophysical phenomena in time to trigger rapid follow-up. We present a science-agnostic metric to supplement detailed simulations of fast-evolving transients and variables and suggest potential approaches for improving the range of timescales explored.

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