2,314 research outputs found
Stochastic thermodynamics for kinetic equations
Stochastic thermodynamics is formulated for variables that are odd under time
reversal. The invariance under spatial rotation of the collision rates due to
the isotropy of the heat bath is shown to be a crucial ingredient. An
alternative detailed fluctuation theorem is derived, expressed solely in terms
of forward statistics. It is illustrated for a linear kinetic equation with
kangaroo rates
Jarzynski equality for the Jepsen gas
We illustrate the Jarzynski equality on the exactly solvable model of a
one-dimensional ideal gas in uniform expansion or compression. The analytical
results for the probability density of the work performed by the gas
are compared with the results of molecular dynamics simulations for a
two-dimensional dilute gas of hard spheres.Comment: 7 pages, 4 figures, submitted to Europhys. Let
Stochastic energetics of a Brownian motor and refrigerator driven by non-uniform temperature
The energetics of a Brownian heat engine and heat pump driven by position
dependent temperature, known as the B\"uttiker-Landauer heat engine and heat
pump, is investigated by numerical simulations of the inertial Langevin
equation. We identify parameter values for optimal performance of the heat
engine and heat pump. Our results qualitatively differ from approaches based on
the overdamped model. The behavior of the heat engine and heat pump, in the
linear response regime is examined under finite time conditions and we find
that the efficiency is lower than that of an endoreversible engine working
under the same condition. Finally, we investigate the role of different
potential and temperature profiles to enhance the efficiency of the system. Our
simulations show that optimizing the potential and temperature profile leads
only to a marginal enhancement of the system performance due to the large
entropy production via the Brownian particle's kinetic energy.Comment: 14 pages, 15 figures (latest version with modified figures and text
Stochastic thermodynamics for Ising chain and symmetric exclusion process
We verify the finite time fluctuation theorem for a linear Ising chain at its
ends in contact with heat reservoirs. Analytic results are derived for a chain
consisting of only two spins. The system can be mapped onto a model for
particle transport, namely the symmetric exclusion process, in contact with
thermal and particle reservoirs. We modify the symmetric exclusion process to
represent a thermal engine and reproduce universal features of the efficiency
at maximum power
Universality of efficiency at maximum power
We investigate the efficiency of power generation by thermo-chemical engines.
For strong coupling between the particle and heat flows and in the presence of
a left-right symmetry in the system, we demonstrate that the efficiency at
maximum power displays universality up to quadratic order in the deviation from
equilibrium. A maser model is presented to illustrate our argument.Comment: 4 pages, 2 figure
Comprehensive study of phase transitions in relaxational systems with field-dependent coefficients
We present a comprehensive study of phase transitions in single-field systems
that relax to a non-equilibrium global steady state. The mechanism we focus on
is not the so-called Stratonovich drift combined with collective effects, but
is instead similar to the one associated with noise-induced transitions a la
Horsthemke-Lefever in zero-dimensional systems. As a consequence, the noise
interpretation (e.g., Ito vs Stratonvich) merely shifts the phase boundaries.
With the help of a mean-field approximation, we present a broad qualitative
picture of the various phase diagrams that can be found in these systems. To
complement the theoretical analysis we present numerical simulations that
confirm the findings of the mean-field theory
A heat pump at a molecular scale controlled by a mechanical force
We show that a mesoscopic system such as Feynman's ratchet may operate as a
heat pump, and clarify a underlying physical picture. We consider a system of a
particle moving along an asymmetric periodic structure . When put into a
contact with two distinct heat baths of equal temperature, the system transfers
heat between two baths as the particle is dragged. We examine Onsager relation
for the heat flow and the particle flow, and show that the reciprocity
coefficient is a product of the characteristic heat and the diffusion constant
of the particle. The characteristic heat is the heat transfer between the baths
associated with a barrier-overcoming process. Because of the correlation
between the heat flow and the particle flow, the system can work as a heat pump
when the particle is dragged. This pump is particularly effective at molecular
scales where the energy barrier is of the order of the thermal energy.Comment: 7 pages, 5 figures; revise
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