نتایج جستجو برای: fluctuation

تعداد نتایج: 26778  

2002
R. KUBO

The linear response theory has given a general proof of the fluctuationdissipation theorem which states that the linear response of a given system to an external perturbation is expressed in terms of fluctuation properties of the system in thermal equilibrium. This theorem may be represented by a stochastic equation describing the fluctuation, which is a generalization of the familiar Langevin ...

2015
Emil Mittag Debra J. Searles Denis J. Evans

2001
B. I. Ivlev

Two interaction mechanisms of particles in a fluid are proposed on base of forces, mediated by hydrodynamic thermal fluctuations. The first one is similar to the conventional van der Waals interaction, but instead of been mediated by electromagnetic fluctuations, it is mediated by fluctuations of hydrodynamic sound waves. The second one is due to a thermal drift of particles to the region with ...

2002
J M Lawrence

Valence fluctuation phenomena occur in rare-earth compounds in which the proximity of the 4f level to the Fermi energy leads to instabilities of the charge configuration (valence) and/or of the magnetic moment. We review the experimental results observed in the subset of such systems for which the 4f ions form a lattice with identical valence on each site. The discussion includes key thermodyna...

Liquid sloshing is a common phenomenon in the transporting of liquid tanks. Liquid waves lead to fluctuating forces on the tank wall. If these fluctuations are not predicted or controlled, they can lead to large forces and momentum. Baffles can control liquid sloshing fluctuations. One numerical method, widely used to model the liquid sloshing phenomena is Smoothed Particle Hydrodynamics (SPH)....

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2008
Peter Talkner Peter Hänggi Manuel Morillo

Previously derived expressions for the characteristic function of work performed on a quantum system by a classical external force are generalized to arbitrary initial states of the considered system and to Hamiltonians with degenerate spectra. In the particular case of microcanonical initial states, explicit expressions for the characteristic function and the corresponding probability density ...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2011
Thomas Butler Nigel Goldenfeld

Models of diffusion-driven pattern formation that rely on the Turing mechanism are utilized in many areas of science. However, many such models suffer from the defect of requiring fine tuning of parameters or an unrealistic separation of scales in the diffusivities of the constituents of the system in order to predict the formation of spatial patterns. In the context of a very generic model of ...

Journal: :Physical review letters 2010
Massimiliano Esposito Christian Van den Broeck

The total entropy production of a trajectory can be split into an adiabatic and a nonadiabatic contribution, deriving, respectively, from the breaking of detailed balance via nonequilibrium boundary conditions or by external driving. We show that each of them, the total, the adiabatic, and the nonadiabatic trajectory entropy, separately satisfies a detailed fluctuation theorem.

Journal: :J. Comput. Physics 2008
Matthew E. Hubbard

This paper describes a new numerical scheme for the approximation of steady state solutions to systems of hyperbolic conservation laws. It generalises the fluctuation distribution framework by allowing the underlying representation of the solution to be discontinuous. This leads to edge-based fluctuations in addition to the standard cell-based fluctuations, which are then distributed to the cel...

2012
R. M. Bryce K. B. Sprague

Half a century ago Hurst introduced Rescaled Range (R/S) Analysis to study fluctuations in time series. Thousands of works have investigated or applied the original methodology and similar techniques, with Detrended Fluctuation Analysis becoming preferred due to its purported ability to mitigate nonstationaries. We show Detrended Fluctuation Analysis introduces artifacts for nonlinear trends, i...

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