131 research outputs found
The geometry and thermodynamics of dissipative quantum systems
Dirac's method of classical analogy is employed to incorporate quantum
degrees of freedom into modern nonequilibrium thermodynamics. The proposed
formulation of dissipative quantum mechanics builds entirely upon the geometric
structures implied by commutators and canonical correlations. A lucid
formulation of a nonlinear quantum master equation follows from the
thermodynamic structure. Complex classical environments with internal structure
can be handled readily.Comment: 4 pages, definitely no figure
Stochastic process behind nonlinear thermodynamic quantum master equation
We propose a piecewise deterministic Markovian jump process in Hilbert space
such that the covariance matrix of this stochastic process solves the
thermodynamic quantum master equation. The proposed stochastic process is
particularly simple because the normalization of the vectors in Hilbert space
is preserved only on average. As a consequence of the nonlinearity of the
thermodynamic master equation, the construction of stochastic trajectories
involves the density matrix as a running ensemble average. We identify a
principle of detailed balance and a fluctuation-dissipation relation for our
Markovian jump process.Comment: 4 page
Thermodynamically admissible form for discrete hydrodynamics
We construct a discrete model of fluid particles according to the GENERIC
formalism. The model has the form of Smoothed Particle Hydrodynamics including
correct thermal fluctuations. A slight variation of the model reproduces the
Dissipative Particle Dynamics model with any desired thermodynamic behavior.
The resulting algorithm has the following properties: mass, momentum and energy
are conserved, entropy is a non-decreasing function of time and the thermal
fluctuations produce the correct Einstein distribution function at equilibrium.Comment: 4 page
Entropy production in phase field theories
Allen-Cahn (Ginzburg-Landau) dynamics for scalar fields with heat conduction
is treated in rigid bodies using a non-equilibrium thermodynamic framework with
weakly nonlocal internal variables. The entropy production and entropy flux is
calculated with the classical method of irreversible thermodynamics by
separating full divergences.Comment: 5 pages, no figure
Маркетинговые исследования рынка потребителей
Данная работа посвящена маркетинговым исследованиям рынка потребителей. В процессе работы были рассмотрены теоретические основы маркетинговых исследований, проводились маркетинговые исследования покупателей магазина «Меркус».
В результате исследования было проведено сегментирование рынка и выявлены постоянные и колеблющиеся потребители. С помощью опроса, в виде анкеты, было определенно отношение покупателей к магазину и их отношение к предложенному товарному ассортименту. С помощью сравнительного метода была определенна конкурентоспособность предприятия. Были разработаны рекомендации и предложения по улучшению маркетинговой деятельности на предприятии «Меркус».This work is dedicated to market research of the consumer market. In the process, the theoretical foundations of marketing research were reviewed, conducted market research magazine "Merkus" buyers.
The study was conducted market segmentation and revealed persistent and fluctuating consumers. With the survey, a questionnaire was definitely the attitude of buyers to the store and their relation to the proposed product portfolio. With the help of the comparative method was definitely the competitiveness of the enterprise. recommendations and suggestions for improvement of marketing activity at the enterprise "Merkus" have been developed
A First Principle Approach to Rescale the Dynamics of Simulated Coarse-Grained Macromolecular Liquids
We present a detailed derivation and testing of our approach to rescale the
dynamics of mesoscale simulations of coarse-grained polymer melts (I. Y.
Lyubimov et al. J. Chem. Phys. \textbf{132}, 11876, 2010). Starting from the
first-principle Liouville equation and applying the Mori-Zwanzig projection
operator technique, we derive the Generalized Langevin Equations (GLE) for the
coarse-grained representations of the liquid. The chosen slow variables in the
projection operators define the length scale of coarse graining. Each polymer
is represented at two levels of coarse-graining: monomeric as a bead-and-spring
model and molecular as a soft-colloid. In the long-time regime where the
center-of-mass follows Brownian motion and the internal dynamics is completely
relaxed, the two descriptions must be equivalent. By enforcing this formal
relation we derive from the GLEs the analytical rescaling factors to be applied
to dynamical data in the coarse-grained representation to recover the monomeric
description. Change in entropy and change in friction are the two corrections
to be accounted for to compensate the effects of coarse-graining on the polymer
dynamics. The solution of the memory functions in the coarse-grained
representations provides the dynamical rescaling of the friction coefficient.
The calculation of the internal degrees of freedom provides the correction of
the change in entropy due to coarse-graining. The resulting rescaling formalism
is a function of the coarse-grained model and thermodynamic parameters of the
system simulated. The rescaled dynamics obtained from mesoscale simulations of
polyethylene, represented as soft colloidal particles, by applying our
rescaling approach shows a good agreement with data of translational diffusion
measured experimentally and from simulations. The proposed method is used to
predict self-diffusion coefficients of new polyethylene samples.Comment: 21 pages, 6 figures, 6 tables. Submitted to Phys. Rev.
A thermodynamic approach to the relaxation of viscosity and thermal conductivity
A novel higher order theory of relaxation of heat and viscosity is proposed
based on corrections to the traditional treatment of the relativistic energy
density. In the framework of generalized Bjorken scaling solution to
accelerating longitudinal flow we point out that the energy flux can be
consequently set to zero in the stationary case, independently of the choice of
a specific local rest frame, like the Landau-Lifshitz or Eckart one. We
investigate and compare several cooling and re-heating scenarios for the Quark
Gluon Plasma (QGP) within this approach.Comment: 13 pages, 4 figure
Boltzmann equation and hydrodynamic fluctuations
We apply the method of invariant manifolds to derive equations of generalized
hydrodynamics from the linearized Boltzmann equation and determine exact
transport coefficients, obeying Green-Kubo formulas. Numerical calculations are
performed in the special case of Maxwell molecules. We investigate, through the
comparison with experimental data and former approaches, the spectrum of
density fluctuations and address the regime of finite Knudsen numbers and
finite frequencies hydrodynamics.Comment: This is a more detailed version of a related paper: I.V. Karlin, M.
Colangeli, M. Kroger, PRL 100 (2008) 214503, arXiv:0801.2932. It contains
comparison between predictions and experiment, in particular. 11 pages, 6
figures, 2 table
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