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Normal and anomalous diffusion are ubiquitous in many complex systems [1] . Here, we define a time and space generalized diffusion equation (GDE), which uses fractional-time derivatives and transformed d-path Laplacian operators on…

Physics and Society · Physics 2022-02-02 Fernando Diaz-Diaz , Ernesto Estrada

Adaptive or dynamic signal sampling in sensing systems can adapt subsequent sampling strategies based on acquired signals, thereby potentially improving image quality and speed. This paper proposes a Bayesian method for adaptive sampling…

Signal Processing · Electrical Eng. & Systems 2023-02-28 Guanhua Wang , Douglas C. Noll , Jeffrey A. Fessler

We study the problem of identifying the dynamics of a linear system when one has access to samples generated by a similar (but not identical) system, in addition to data from the true system. We use a weighted least squares approach and…

Systems and Control · Electrical Eng. & Systems 2022-04-13 Lei Xin , Lintao Ye , George Chiu , Shreyas Sundaram

The long-term evolution of astrophysical systems is driven by a Hamiltonian that is independent of the fast angle. As this Hamiltonian may contain explicitly time-dependent parameters, the conservation of mechanical energy is not guaranteed…

Earth and Planetary Astrophysics · Physics 2024-05-29 Barnabás Deme

I investigate the possibility that explicit solutions of stochastic reaction-diffusion equations can be found by multiplying the deterministic travelling waves with a stochastic exponent. This approach has become widespread in the…

Analysis of PDEs · Mathematics 2026-03-27 C. H. S. Hamster

Time series observations are ubiquitous in astronomy, and are generated to distinguish between different types of supernovae, to detect and characterize extrasolar planets and to classify variable stars. These time series are usually…

Instrumentation and Methods for Astrophysics · Physics 2018-09-13 Susana Eyheramendy , Felipe Elorrieta , Wilfredo Palma

Spatial-temporal forecasting has attracted tremendous attention in a wide range of applications, and traffic flow prediction is a canonical and typical example. The complex and long-range spatial-temporal correlations of traffic flow bring…

Machine Learning · Computer Science 2021-06-25 Zheng Fang , Qingqing Long , Guojie Song , Kunqing Xie

We propose a novel numerical approach for nonlocal diffusion equations [8] with integrable kernels, based on the relationship between the backward Kolmogorov equation and backward stochastic differential equations (BSDEs) driven by L\`{e}vy…

Numerical Analysis · Mathematics 2015-07-28 Guannan Zhang , Weidong Zhao , Clayton Webster , Max Gunzburger

Nonlinear time series analysis has been widely used to search for signatures of low-dimensional chaos in light curves emanating from astrophysical bodies. A particularly popular example is the microquasar GRS 1915+105, whose irregular but…

High Energy Astrophysical Phenomena · Physics 2016-12-20 Manu Mannattil , Himanshu Gupta , Sagar Chakraborty

One of the main science goals of the Large Synoptic Survey Telescope (LSST) is to uncover the nature of cosmic acceleration. In the base analysis, possible deviations from the Lambda-Cold-Dark-Matter ($\Lambda$CDM) background evolution will…

Experimental data is often affected by uncontrolled variables that make analysis and interpretation difficult. For spatiotemporal systems, this problem is further exacerbated by their intricate dynamics. Modern machine learning methods are…

Computational Physics · Physics 2020-09-16 Peter Y. Lu , Samuel Kim , Marin Soljačić

We demonstrate how, with a purely empirical analysis of the irregular lightcurve data, one can extract a great deal of information about the stellar pulsation mechanism. An application to R Sct thus shows that the irregular lightcurve is…

Astrophysics · Physics 2016-01-27 J. Robert Buchler , Zoltan Kollath

To understand the observational properties of cosmological models, in particular, the temperature of the cosmic microwave background radiation, it is necessary to study their null geodesics. Dynamical systems theory, in conjunction with the…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Ulf S Nilsson , C. Uggla , J. Wainwright

Stellar dynamics is almost unreasonably well suited for an implementation in terms of special-purpose hardware. Unlike the case of molecular dynamics, stellar dynamics deals exclusively with a long-range force, gravity, which leads to a…

Astrophysics · Physics 2007-05-23 Piet Hut

We describe a simple stochastic method, so-called Langevin approach, which enables one to extract evolution equations of stochastic variables from a set of measurements. Our method is parameter-free and it is based on the nonlinear Langevin…

Data Analysis, Statistics and Probability · Physics 2015-02-19 Nico Reinke , André Fuchs , Wided Medjroubi , Pedro G. Lind , Matthias Wächter , Joachim Peinke

In the era of rapidly increasing amounts of time series data, classification of variable objects has become the main objective of time-domain astronomy. Classification of irregularly sampled time series is particularly difficult because the…

Instrumentation and Methods for Astrophysics · Physics 2015-05-21 Sven Dennis Kügler , Nikos Gianniotis , Kai Lars Polsterer

Given nonstationary data from molecular dynamics simulations, a Markovian Langevin model is constructed that aims to reproduce the time evolution of the underlying process. While at equilibrium the free energy landscape is sampled,…

Computational Physics · Physics 2021-07-20 Benjamin Lickert , Steffen Wolf , Gerhard Stock

We explore the idea that non-equilibrium steady states breaking detailed balance are obtained by deforming trajectories (lines in space-time) that have been sampled in a reference system with stochastic dynamics obeying detailed balance,…

Statistical Mechanics · Physics 2018-04-17 Thomas Speck

Astronomical data are typically irregular in time, e.g. the space (HIPPARCOS/TYCHO, KEPLER, GAIA, WISE etc.) and ground-based CCD (NSVS, ASAS, CRTS, SuperWASP etc.) and photographic (Harvard, Sonneberg, Odessa etc.) photometrical surveys.…

Solar and Stellar Astrophysics · Physics 2019-02-05 Ivan L. Andronov

Understanding physical phenomena oftentimes means understanding the underlying dynamical system that governs observational measurements. While accurate prediction can be achieved with black box systems, they often lack interpretability and…

Machine Learning · Computer Science 2021-07-16 Juliane Weilbach , Sebastian Gerwinn , Christian Weilbach , Melih Kandemir