共查询到20条相似文献,搜索用时 15 毫秒
1.
A. E. Patrick 《Journal of statistical physics》2007,128(5):1211-1235
We investigate the properties of the Gibbs states and thermodynamic observables of the spherical model in a random field.
We show that on the low-temperature critical line the magnetization of the model is not a self-averaging observable, but it
self-averages conditionally. We also show that an arbitrarily weak homogeneous boundary field dominates over fluctuations
of the random field once the model transits into a ferromagnetic phase. As a result, a homogeneous boundary field restores
the conventional self-averaging of thermodynamic observables, like the magnetization and the susceptibility. We also investigate
the effective field created at the sites of the lattice by the random field, and show that at the critical temperature of
the spherical model the effective field undergoes a transition into a phase with long-range correlations ∼r
4−d
. 相似文献
2.
3.
We study the spin glass system consisting of a Random Energy Model coupled with a random magnetic field. This system was investigated by de Oliveira Filho et al. (Phys Rev E 74:031117, 2006) who computed the free energy. In this paper, we recover their result rigorously using elementary large deviations arguments and a conditional second moment method. Our analysis extends at the level of fluctuations of the ground states. In particular, we prove that the joint distribution of the minimal energies has the law of a Poisson process with exponential density after a recentering, which is random as opposed to the standard REM. One consequence is that the Gibbs measure of the model exhibits a one-step replica symmetry breaking as argued by de Oliveira Filho et al. using the replica method. 相似文献
4.
Random field spin-S Ising model with a transverse field has been studied by making use of the pair approximation with the discretized path-integral representation, and an analytical expression of second-order phase transition is derived for all the symmetric probability distributions of (longitudinal) random fields. The phase diagrams at T = 0 are obtained, and the conditions for existence of tricritical points are examined for an arbitrary number of nearest-neighbor spins. 相似文献
5.
In the paper, we consider the transport of a two-dimensional random walk. The velocity and the dispersion of this two-dimensional random walk are derived. It mainly show that: (i) by controlling the values of the transition rates, the direction of the random walk can be reversed; (ii) for some suitably selected transition rates, our two-dimensional random walk can be efficient in comparison with the one-dimensional random walk. Our work is motivated in part by the challenge to explain the unidirectional transport of motor proteins. When the motor proteins move at the turn points of their tracks (i.e., the cytoskeleton filaments and the DNA molecular tubes), some of our results in this paper can be used to deal with the problem. 相似文献
6.
The operation of an acoustic transducer in a temperature-stratified medium is investigated. The formation of a response of piezoceramic transducers of pressure fluctuations under the action of temperature fluctuations in a working medium on the sensor element is considered. The attenuation of the temperature signal of a pressure transducer in a turbulent boundary layer is calculated numerically. The effect of distortions of the spectral levels of pressure fluctuations detected by a sound transducer in the field of temperature inhomogeneities is investigated for the example of measurements of turbulent pressure fluctuations in a boundary layer during vertical ascent of the device to the surface from a specified depth in a deep sea. 相似文献
7.
We consider the problem of phase fluctuations of radio waves behind a turbulent optically thin irregular layer (phase screen).
Expressions are derived for the main statistical characteristics of phase fluctuations in the case where modern direct methods
based on measurements of the complex field of the received radiation are used to obtain these characteristics. Regimes of
weak and saturated scintillations of signals are analyzed. It is shown that in the case of weak scintillations, such statistical
characteristics of phase fluctuations of the received radiation as the structure function and the fluctuation spectra for
single-point and interference reception almost coincide with those at the screen output. In the regime of saturated scintillations,
we obtain an information on the structure function of phase fluctuations of the received radiation in the cases of relatively
large and small spatial separations of the reception points. The results obtained allow one to correctly analyze the data
of modern experiments on remote sensing of the near-Earth and space plasmas with the help of direct phase methods for environmental
diagnostics.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 7, pp. 563–573, July 2005. 相似文献
8.
9.
LI Ke-Ping 《理论物理通讯》2006,45(1):113-116
In this paper, we propose a new cellular automaton model, which is
based on NaSch traffic model. In our method, when a car has a larger
velocity, if the gap between the car and its leading car is not enough
large, it will decrease. The aim is that the following car
has a buffer space to decrease its velocity at the next time, and then
avoid to decelerate too high. The simulation results show that using our
model, the car deceleration is realistic, and is closer
to the field measure than that of NaSch model. 相似文献
10.
We study the critical behavior of the surface on a semi-infinite simple cubic lattice Ising model with a bimodal random surface field by large cell mean-field renormaliza tion group method and Monte Carlo simulations. Our results show that the surface ferromagnetic phase exists in the weak random field range above the bulk critical temperature. The surface. specific heat is not divergence and the susceptibility show a cusp singularity at the surface ferromagnetic-paramagnetic transition for a relatively large and om field. 相似文献
11.
JETP Letters - The influence of a high (~1 V/nm) external electric field on biological soft matter systems has been widely studied for a long time. However, a detailed understanding of the behavior... 相似文献
12.
Timo Seppäläinen 《Communications in Mathematical Physics》2002,229(1):141-182
We study central limit theorems for a totally asymmetric, one-dimensional interacting random system. The models we work with
are the Aldous–Diaconis–Hammersley process and the related stick model. The A-D-H process represents a particle configuration
on the line, or a 1-dimensional interface on the plane which moves in one fixed direction through random local jumps. The
stick model is the process of local slopes of the A-D-H process, and has a conserved quantity. The results describe the fluctuations
of these systems around the deterministic evolution to which the random system converges under hydrodynamic scaling. We look
at diffusive fluctuations, by which we mean fluctuations on the scale of the classical central limit theorem. In the scaling
limit these fluctuations obey deterministic equations with random initial conditions given by the initial fluctuations. Of
particular interest is the effect
of macroscopic shocks, which play a dominant role because dynamical noise is suppressed on the scale we are working.
Received: 4 October 2001 / Accepted: 12 March 2002 相似文献
13.
The circular and Jacobi ensembles of random matrices have their eigenvalue support on the unit circle of the complex plane and the interval (0,1) of the real line respectively. The averaged value of the modulus of the corresponding characteristic polynomial raised to the power 2 diverges, for 2 –1, at points approaching the eigenvalue support. Using the theory of generalized hypergeometric functions based on Jack polynomials, the functional form of the leading asymptotic behaviour is established rigorously. In the circular ensemble case this confirms a conjecture of Berry and Keating. 相似文献
14.
A comparison between the standard adiabatic piston dynamics and that of a perfectly conducting (diathermal) piston helps to
clarify their different behaviors and, in particular, the anomalously large random displacement of the adiabatic piston as
compared to the diathermal one. It is shown to be associated with a situation where the presence of a single massive “particle”
(the piston), acting as an internal constraint in a many-particle system, plays a somewhat unexpected relevant role. A significant
physical insight accounting for the above difference is gained by means of a simple analysis of the phase space available
to our system. 相似文献
15.
Alain-Sol Sznitman 《Communications in Mathematical Physics》1997,189(2):337-363
We investigate the principal Dirichlet eigenvalue of the Laplacian with soft Poissonian obstacles in large boxes of , d≥ 2. With the help of our recent version of the method of enlargement of obstacles [18], we derive quantitative confidence
intervals for these eigenvalues. We also provide less quantitative estimates, which however point out the correct size of
fluctuations, and indicate a stiffness in their behavior. In the two-dimensional case we derive geometric controls, which
relate these eigenvalues to certain empty circular droplets. Our results also have natural applications to the study of the
location of minima of certain intermittent random variational problems, motivated by [13, 17].
Received: 13 June 1996 / Accepted: 10 March 1997 相似文献
16.
We study the dynamics of a spin-flip model with a mean field interaction. The system is non reversible, spacially inhomogeneous,
and it is designed to model social interactions. We obtain the limiting behavior of the empirical averages in the limit of
infinitely many interacting individuals, and show that phase transition occurs. Then, after having obtained the dynamics of
normal fluctuations around this limit, we analyze long time fluctuations for critical values of the parameters. We show that
random inhomogeneities produce critical fluctuations at a shorter time scale compared to the homogeneous system. 相似文献
17.
We compare the spectral properties of long meteorological temperature records with laboratory measurements in small convection cells. Surprisingly, the atmospheric boundary layer sampled on a daily scale shares the statistical properties of temperature fluctuations in small-scale experiments. This fact can be explained by the hydrodynamical similarity between these seemingly very different systems. The results suggest that the dynamics of daily temperature fluctuations is determined by the soft turbulent state of the atmospheric boundary layer in the continental climate. 相似文献
18.
We study a model of mass-bearing coagulating-fragmenting planar Brownian particles. Coagulation occurs when two particles
are within a distance of order ε. Our model is macroscopically described by an inhomogeneous Smoluchowski’s equation in the low ε limit provided that the initial number of particles N is of order |log ε|. When a detailed balance condition is satisfied, we establish a central limit theorem by showing that in the low ε limit, the particle density fluctuation fields obey an Ornstein-Uhlenbeck stochastic differential equation. 相似文献
19.
V. V. Titov R. A. Stepanov D. D. Sokoloff 《Journal of Experimental and Theoretical Physics》2018,126(4):566-572
We consider the influence of fluctuations in a screw flow of a conducting liquid on the effect of magnetic field self-excitation; the solution of this problem is important for experimental realization of a turbulent dynamo. We propose a theoretical approach based on the solution of averaged equations obtained in the limit of a short correlation time. The applicability of this approach is confirmed by direct numerical simulation of the initial equations. We demonstrate the influence of the correlation of fluctuations on the dynamo effect threshold. It is shown that the solution of the mean-field equations differs from the solution based on direct numerical simulation for a finite correlation time. The advantages and disadvantages of the two approaches are estimates, as well as the importance of the discovered difference in the context of problems of magnetic field self-excitation. The influence of helicity and intermittency on the type of the solution is considered. 相似文献
20.
Thermodynamical Properties of Spin-3/2 Ising Model in a Longitudinal Random Field with Crystal Field
A theoretical study of a spin-3/2 Ising model in a
longitudinal random field with crystal field is studied by using of the
effective-field theory with correlations. The phase diagrams and the
behavior of the tricritical point are investigated numerically for the
honeycomb lattice when the random field is bimodal. In particular, the
specific heat and the internal energy are examined in detail for the system
with a crystal-field constant in the critical region where the ground-state
configuration may change from the spin-3/2 state to the
spin-1/2 state. We find many interesting phenomena in the
system. 相似文献