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We investigate the standard deviation $\delta v(\tsamp)$ of the variance $v[\xbf]$ of time series $\xbf$ measured over a finite sampling time $\tsamp$ focusing on non-ergodic systems where independent "configurations" $c$ get trapped in…

Statistical Mechanics · Physics 2021-03-15 G. George , L. Klochko , A. N. Semenov , J. Baschnagel , J. P. Wittmer

We present technical results required for the description and understanding of correlations and fluctuations of the empirical density and current as well as diverse time-integrated and time-averaged thermodynamic currents of diffusion…

Statistical Mechanics · Physics 2023-01-09 Cai Dieball , Aljaž Godec

The absence of self averaging in mesoscopic systems is a consequence of long-range intensity correlation. Microwave measurements suggest and diagrammatic calculations confirm that the correlation function of the normalized intensity with…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 P. Sebbah , B. Hu , A. Z. Genack , R. Pnini , B. Shapiro

Hydrodynamic fluctuations in simple fluids under shear flow are demonstrated to be spatially correlated, in contrast to the fluctuations at equilibrium, using mesoscopic hydrodynamic simulations. The simulation results for the equal-time…

Soft Condensed Matter · Physics 2024-06-03 Anoop Varghese , Gerhard Gompper , Roland G. Winkler

Conventional practice of spatially resolved detection in diffusion-coupled thermal atomic vapors implicitly treat localized responses as mutually independent. However, in this study, it is shown that observable correlations are governed by…

Atomic Physics · Physics 2026-01-01 Zuoxian Wang , Yuhao Zhang , Gaopu Hou , Zihua Liang , Gen Hu , Lu Liu , Yuan Sun , Feilong Xu , Mao Ye

The variability of temporal (or spatial) fluctuations of any variable is represented in conventional statistical theory by the relative dispersion equal to the standard deviation divided by the mean . The Relative Dispersion decreases with…

chao-dyn · Physics 2007-05-23 A. M. Selvam , Suvarna Fadnavis , S. U. Athale

We examine fluctuations of vorticity inside the coherent vortex, appearing as a consequence of the inverse energy cascade in two-dimensional turbulence. Temporal and spacial correlations can be characterized by the pair correlation…

Fluid Dynamics · Physics 2024-03-07 Igor V. Kolokolov , Vladimir V. Lebedev , Mariya M. Tumakova

This paper reviews some of the principal uses, over almost seven decades, of correlations, in both Eulerian and Lagrangian frames of reference, of properties of turbulent flows at variable spatial locations and variable time instants.…

Fluid Dynamics · Physics 2015-08-07 James M. Wallace

Designing a covariance function that represents the underlying correlation is a crucial step in modeling complex natural systems, such as climate models. Geospatial datasets at a global scale usually suffer from non-stationarity and…

Machine Learning · Statistics 2015-07-10 Chintan A. Dalal , Vladimir Pavlovic , Robert E. Kopp

Spatio-temporal covariances are important for describing the spatio-temporal variability of underlying random processes in geostatistical data. For second-order stationary processes, there exist subclasses of covariance functions that…

Applications · Statistics 2017-05-05 Huang Huang , Ying Sun

In a first part the scope of classical thermodynamics and statistical mechanics is discussed in the broader context of formal dynamical systems, including computer programmes. In this context classical thermodynamics appears as a particular…

Statistical Mechanics · Physics 2009-11-11 Daniel Pfenniger

For non-equilibrium systems of interacting particles and for interacting diffusions in d dimensions, a novel fluctuation relation is derived. The theorem establishes a quantitative relation between the probabilities of observing two current…

Statistical Mechanics · Physics 2015-12-07 Carlos Pérez-Espigares , Frank Redig , Cristian Giardinà

Standard results for the fluctuations of thermodynamic quantities are derived under the assumption of sampling identical systems that are in different, not fully equilibrated states. These results apply to fluctuations with time in a…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 R. A. Serota

Atmospheric flows exhibit fluctuations of all scales (space -time) ranging from turbulence (millimeters-seconds) to climate (thousands of kilometers-years). The apparently random fluctuations however exhibit long-range spatio-temporal…

chao-dyn · Physics 2009-09-25 Suvarna Fadnavis , A. M. Selvam

Extending recent work on stress fluctuations in complex fluids and amorphous solids we describe in general terms the ensemble average $v(\Delta t)$ and the standard deviation $\delta v(\Delta t)$ of the variance $v[\mathbf{x}]$ of time…

Statistical Mechanics · Physics 2020-11-18 G. George , L. Klochko , A. N. Semenov , J. Baschnagel , J. P. Wittmer

In order to account for possible nonstatistical fluctuations in a hadronizing system (leading to the characteristic power-like behavior of the respective single particle spectra and to the broadening of the corresponding multiparticle…

High Energy Physics - Phenomenology · Physics 2012-02-21 Grzegorz Wilk , Zbigniew Wlodarczyk

We present simple classical dynamical models to illustrate the idea of introducing a stochasticity with non-locality into the time variable. For stochasticity in time, these models include noise in the time variable but not in the "space"…

General Physics · Physics 2007-05-23 Toru Ohira

We develop non-equilibrium theory by using averages in time and space as a generalized way to upscale thermodynamics in non-ergodic systems. The approach offers a classical perspective on the energy dynamics in fluctuating systems. The rate…

Soft Condensed Matter · Physics 2021-09-29 James E. McClure , Steffen Berg , Ryan T. Armstrong

Correlated fluctuations in the activity of neural populations reflect the network's dynamics and connectivity. The temporal and spatial dimensions of neural correlations are interdependent. However, prior theoretical work mainly analyzed…

Neurons and Cognition · Quantitative Biology 2022-07-19 Yan-Liang Shi , Roxana Zeraati , Anna Levina , Tatiana A. Engel

Time-averaged autocorrelation functions of a dichotomous random process switching between 1 and 0 and governed by wide power law sojourn time distribution are studied. Such a process, called a L\'evy walk, describes dynamical behaviors of…

Statistical Mechanics · Physics 2007-05-23 Gennady Margolin , Eli Barkai
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