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Nonextensive perfect hydrodynamics - a model of dissipative relativistic hydrodynamics?

100%
Osada T., Wilk G.
Open Physics
|
2009
|
vol. 7
|
issue 3
432-443
EN
We demonstrate that nonextensive perfect relativistic hydrodynamics (q-hydrodynamics) can serve as a model of the usual relativistic dissipative hydrodynamics (d-hydrodynamics) therefore facilitating considerably its applications. As an illustration, we show how using q-hydrodynamics one gets the q-dependent expressions for the dissipative entropy current and the corresponding ratios of the bulk and shear viscosities to entropy density, ζ/s and η/srespectively.
2
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Fluctuation theorems from non-equilibrium Onsager-Machlup theory for a Brownian particle in a time-dependent harmonic potential

100%
Deza R., Izús G., Wio H.
Open Physics
|
2009
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vol. 7
|
issue 3
472-478
EN
We discuss the case of a Brownian particle which is harmonically bound and multiplicatively forced-namely bound by V(x,t)=1/2 a(t)x 2 where a(t)is externally controlled-as another instance that provides a generalization of Onsager-Machlup’s theory to non-equilibrium states, thus allowing establishment of several fluctuation theorems. In particular, we outline the derivation of a fluctuation theorem for work, through the calculation of the work probability distribution as a functional integral over stochastic trajectories.
3
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Exact and approximate statistical approaches for the exergy of blackbody radiation

100%
Badescu V.
Open Physics
|
2008
|
vol. 6
|
issue 2
344-350
EN
There is a long term debate in literature about the exergy of blackbody radiation (BBR). Most authors contributing to this dispute used classical thermodynamics arguments. The objective of this paper is to propose a statistical thermodynamics approach. This gives new perspectives to previous results. Four simple statistical microscopic models are used to derive BBR exergy. They consist of combinations of quantum and classical descriptions of the state occupation number and entropy, respectively. In all four cases the BBR exergy (or exergy flux density) is given by the internal energy (or energy flux density) times an efficiency-like factor containing the environment temperature and the blackbody radiation temperature. One shows that Petela-Landsberg-Press efficiency is the “exact” result while the Jeter (Carnot) efficiency corresponds to the classical approximation. Other two (new) approximate efficiency-like factors are also reported.
4
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Exergy of nuclear radiation - a quantum statistical thermodynamics approach

100%
Badescu V.
Open Physics
|
2009
|
vol. 7
|
issue 1
141-146
EN
The exergy of nuclear radiation is evaluated by using a simple quantum statistical thermodynamic approach. Only radiation particles with non-zero rest mass are considered (i.e. protons, neutrons, alpha and beta particles). The exergy and the exergy flux involve efficiency-like factors affecting the internal energy and the energy flux, respectively. These factors are generally different from both the usual Carnot factor and the Petela-Landsberg-Press factor that appears in the exergy of blackbody radiation. The efficiency-like factors are higher in the case of charged rather than neutral particles and in the case of enclosed rather than free radiation. The results are compared with those obtained previously by using a classical thermodynamic theory.
5
Content available remote

Instability transitions and ensemble equivalence in diffusive flow

84%
Ha M.
Open Physics
|
2009
|
vol. 7
|
issue 3
575-583
EN
We investigate the critical behavior of one-dimensional (1D) stochastic flow with competing nonlocal and local hopping events, in context of the totally asymmetric simple exclusion process (TASEP) with a defect site in a 1D closed chain. The defect site can effectively generate various boundary conditions, controlling the total number of particles in the system. Both open and periodic-like setups exhibit dynamic instability transitions from a populated finite density phase to an empty road (ER) phase as the nonlocal hopping rate increases. In the stationary populated phase, strong clustering promoted by nonlocal skids drives such transitions and determines their scaling properties. By static and dynamic simulations, we locate such transition points, and discuss their nature and scaling properties. In the open TASEP variant, we numerically establish that the instability transition into the ER phase is second order in the regime where the entry point reservoir controls the current, while it is first order in the regime where the bulk controls the current. Since it is well known that such transitions are absent in the periodic TASEP variant, we compare our results in the open setup with those in the periodic-like setup, and discuss the issue of the ensemble equivalence. Finally, the same discussion is extended to the symmetric cases.
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