共查询到20条相似文献,搜索用时 31 毫秒
1.
In order to describe quantum fluctuations a general method is developed, which also may be applied to nonstationary systems as well as to states far from thermodynamic equilibrium. After a concise derivation of the master equation quantum mechanically determined dissipation and fluctuation coefficients are introduced, for which several theorems and relations are given. By using these coefficients there is set up a general Fokker-Planck equation for the diffusion of the statistical operator due to quantum fluctuations. 相似文献
2.
Robert J. Deissler 《Journal of statistical physics》1985,40(3-4):371-395
The time-dependent generalized Ginzburg-Landau equation is an equation that is related to many physical systems. Solutions of this equation in the presence of low-level external noise are studied. Numerical solutions of this equation in thestationary frame of reference and with anonzero group velocity that is greater than a critical velocity exhibit a selective spatial amplification of noise resulting in spatially growing waves. These waves in turn result in the formation of a dynamic structure. It is found that themicroscopic noise plays an important role in themacroscopic dynamics of the system. For certain parameter values the system exhibits intermittent turbulent behavior in which the random nature of the external noise plays a crucial role. A mechanism which may be responsible for the intermittent turbulence occurring in some fluid systems is suggested. 相似文献
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We derive asymptotically an order parameter equation in the limit where nascent bistability and long-wavelength modulation instabilities coalesce. This equation is a variant of the Swift-Hohenberg equation that generally contains nonvariational terms of the form psinabla(2)psi and /nablapsi/(2). We briefly review some of the properties already derived for this equation and derive it on three examples taken from chemical, biological, and optical contexts. Finally, we derive the equation on a general class of partial differential systems. 相似文献
5.
D. Bedeaux 《Physics letters. A》1977,62(1):10-12
It is shown that the random force in the Langevin equation for a nonlinear system may be chosen in such a way that the resulting equation is mathematically equivalent to the master equation. 相似文献
6.
Lee MH 《Physical review letters》2000,85(12):2422-2425
Fick's law is important in transport theory and nonequilibrium statistical mechanics. The Heisenberg equation of motion for density is examined to see how it could be reduced to the diffusion equation, which is exactly equivalent to Fick's law. Conditions that are required have been noted and their implications explored. 相似文献
7.
V. M. Kenkre 《Journal of statistical physics》1983,30(2):293-303
Techniques developed recently for the study of exciton dynamics in molecular solids are discussed. They include master equation methods for the analysis of prerelaxation energy transfer, the generalized master equation approach to coherence in exciton motion, and the defect technique as applied to exciton trapping and annihilation. 相似文献
8.
Willi-Hans Steeb 《Physica A》1979,95(1):181-190
The relation between the generalized Liouville equation, entropy production rates and autonomous systems of differential equations containing limit cycles is investigated. Moreover, the connection between the generalized Liouville equation and the Lie derivative of a differential form with respect to a vector field is discussed. 相似文献
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The matrix Ernst equation (a reduced form of the self-dual Yang-Mills equation) is written as the compatibility condition for solution of a linear “inverse scattering” system. This system is used to construct infinite sequences of nonlocal conserved charges, as well as an infinitesimal hidden symmetry transformation, for the Ernst equation. 相似文献
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Collective field theory for the Calogero model represents particles with fractional statistics in terms of hydrodynamic modes--density and velocity fields. We show that the quantum hydrodynamics of this model can be written as a single evolution equation on a real holomorphic Bose field--the quantum integrable Benjamin-Ono equation. It renders tools of integrable systems to studies of nonlinear dynamics of 1D quantum liquids. 相似文献
13.
The metric connection on a space-time manifoldM defines on its tangent bundleTM a distribution of subspaces complementary to the vertical subspaces and therefore called horizontal. We give a formula for the Lie derivative with respect to the geodesic spray of the tensor field onTM which defines projection onto the vertical subspace along the horizontal subspace; and we show that this formula is a universal version of the equation, for a geodesic local vector field onM, whose trace is Raychaudhuri's equation. 相似文献
14.
New exact solitary wave solutions to generalized mKdV equation and generalized Zakharov--Kuzentsov equation 总被引:2,自引:0,他引:2 下载免费PDF全文
In this paper,
based on hyperbolic tanh-function method and homogeneous balance
method, and auxiliary equation method, some new exact solitary
solutions to the generalized mKdV equation and generalized
Zakharov--Kuzentsov equation are constructed by the method of
auxiliary equation with function transformation with aid of
symbolic computation system Mathematica. The method is of important
significance in seeking new exact solutions to the evolution
equation with arbitrary nonlinear term. 相似文献
15.
In this paper, we deal with the complete algebra of Lie point symmetries for the generalized model of an irrigation system of fractional order. By means of Lie symmetry method, the vector fields has been investigated which are utilized for obtaining the conservation laws of equation. In addition, through the sub-equation method, we construct some exact solutions for the considered equation by reducing the fractional partial differential equation to a ordinary fractional differential equation. 相似文献
16.
Saroj K Majumdar 《Pramana》1973,1(3):129-134
An attempt is made to derive a simple form of the collision integral of the kinetic equation for a plasma, by using Rostoker’s
equation which expresses the pair correlation function in terms of the distribution functions of the particles, and the conditional
probability of one particle shielding the other. The conditional probability function is assumed to be given by its equilibrium
value. By taking first order velocity-moment of the resulting kinetic equation, the equation of momentum transfer has been
obtained. 相似文献
17.
Hu Gang 《Zeitschrift für Physik B Condensed Matter》1986,64(2):247-252
The master equation and the Fokker-Planck equation are compared thoroughly in both of the stationary and the time-dependent cases for a one-dimensional system. The comparison includes the master equation without detailed balance. 相似文献
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H. Grabert 《Zeitschrift für Physik B Condensed Matter》1977,26(1):79-83
It is shown that the generalized Langevin equation derived by Mori is equivalent to the generalized master equation of Nakajima and Zwanzig. Both equations of motion are related, just in the same way as Heisenberg and Schrödinger picture are related. 相似文献