971 research outputs found
Energetics of Open Systems and Chemical Potential From Micro-Dynamics Viewpoints
We present the energetic aspect of open systems which may exchange particles
with their environments. Our attention shall be paid to the scale that the
motion of the particles is described by the classical Langevin dynamics. Along
a particular realization of the stochastic process, we study the energy
transfer into the open system from the environments. We are able to clarify how
much energy each particle carries when it enters or leaves the system. On the
other hand, the chemical potential should be considered as the concept in macro
scale, which is relevant to the free energy potential with respect to the
number of particles. Keywords: open systems, stochastic energetics, chemical
potentialComment: 7 pages, 1 figur
Equilibrium Chemical Engines
An equilibrium reversible cycle with a certain engine to transduce the energy
of any chemical reaction into mechanical energy is proposed. The efficiency for
chemical energy transduction is also defined so as to be compared with Carnot
efficiency. Relevance to the study of protein motors is discussed. KEYWORDS:
Chemical thermodynamics, Engine, Efficiency, Molecular machine.Comment: 5 pages, late
Fluctuation relations for a driven Brownian particle
We consider a driven Brownian particle, subject to both conservative and
non-conservative applied forces, whose probability evolves according to the
Kramers equation. We derive a general fluctuation relation, expressing the
ratio of the probability of a given Brownian path in phase space with that of
the time-reversed path, in terms of the entropy flux to the heat reservoir.
This fluctuation relation implies those of Seifert, Jarzynski and
Gallavotti-Cohen in different special cases
Jarzynski equality for the transitions between nonequilibrium steady states
Jarzynski equality [Phys. Rev. E {\bf 56}, 5018 (1997)] is found to be valid
with slight modefication for the transitions between nonequilibrium stationary
states, as well as the one between equilibrium states. Also numerical results
confirm its validity. Its relevance for nonequilibrium thermodynamics of the
operational formalism is discussed.Comment: 5 pages, 2 figures, revte
The Carnot Cycle for Small Systems: Irreversibility and the Cost of Operations
We employ the recently developed framework of the energetics of stochastic
processes (called `stochastic energetics'), to re-analyze the Carnot cycle in
detail, taking account of fluctuations, without taking the thermodynamic limit.
We find that both processes of connection to and disconnection from heat
baths and adiabatic processes that cause distortion of the energy distribution
are sources of inevitable irreversibility within the cycle. Also, the so-called
null-recurrence property of the cumulative efficiency of energy conversion over
many cycles and the irreversible property of isolated, purely mechanical
processes under external `macroscopic' operations are discussed in relation to
the impossibility of a perpetual machine, or Maxwell's demon.Comment: 11 pages with 3 figures. Resubmitted to Physical Review E. Many
paragraphs have been modifie
Microscopic heat from the energetics of stochastic phenomena
The energetics of the stochastic process has shown the balance of energy on
the mesoscopic level. The heat and the energy defined there are, however,
generally different from their macroscopic counterpart. We show that this
discrepancy can be removed by adding to these quantities the reversible heat
associated with the mesoscopic free energy.Comment: 4 pages, 0 figur
Brownian dynamics around the core of self-gravitating systems
We derive the non-Maxwellian distribution of self-gravitating -body
systems around the core by a model based on the random process with the
additive and the multiplicative noise. The number density can be obtained
through the steady state solution of the Fokker-Planck equation corresponding
to the random process. We exhibit that the number density becomes equal to that
of the King model around the core by adjusting the friction coefficient and the
intensity of the multiplicative noise. We also show that our model can be
applied in the system which has a heavier particle. Moreover, we confirm the
validity of our model by comparing with our numerical simulation.Comment: 11 pages, 4 figure
Brownian Motors driven by Particle Exchange
We extend the Langevin dynamics so that particles can be exchanged with a
particle reservoir. We show that grand canonical ensembles are realized at
equilibrium and derive the relations of thermodynamics for processes between
equilibrium states. As an application of the proposed evolution rule, we devise
a simple model of Brownian motors driven by particle exchange. KEYWORDS:
Langevin Dynamics, Thermodynamics, Open SystemsComment: 5 pages, late
Lithophile element characteristics of acapulcoite-lodranite.
第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月18日(金) 国立国語研究所 2階講
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