共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
3.
A. Bershadskii 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(4):691-693
It is shown that multifractal properties of some random and disordered systems can be simulated using thermodynamics of a
generalized ideal monoatomic gas in a fractal phase space.
Received 25 November 1998 and Received in final form 16 December 1998 相似文献
4.
M. A. Fuentes H. S. Wio 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(2):249-253
With the aim of studying stochastic resonance (SR) in a
double-well potential when the noise source has a spectral density
of the form f-κ (with varying κ), we have extended
a procedure introduced by Kaulakys et al. (Phys. Rev. E 70,
020101 (2004)). In order to achieve an analytical understanding of
the results, we have obtained an effective Markovian approximation
that allows us to make a systematic study of the effect of such
noise on the SR phenomenon. A comparison of the numerical and
analytical results shows an excellent qualitative agreement
indicating that the effective Markovian approximation is able to
correctly describe the general trends. 相似文献
5.
L. F. Matin A. Aghamohammadi M. Khorrami 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(3):243-246
The most general reaction-diffusion model on a Cayley
tree with nearest-neighbor interactions is introduced, which can
be solved exactly through the empty-interval method. The
stationary solutions of such models, as well as their dynamics,
are discussed. Concerning the dynamics, the spectrum of the
evolution Hamiltonian is found and shown to be discrete, hence
there is a finite relaxation time in the evolution of the system
towards its stationary state. 相似文献
6.
E. Scalas U. Garibaldi S. Donadio 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(2):271-272
This erratum corrects a mistake in reference [E. Scalas, U. Garibaldi, S. Donadio, Eur. Phys. J. B 53, 267 (2006)].
In that paper,
we needed an aperiodic version of the BDY game, but, in formula (1),
we incorrectly presented
a periodic transition matrix of period 2 in the special case of g = 2 agents.
Here, we present the right aperiodic version. 相似文献
7.
Stochastic multiresonance in a bistable sawtooth potential driven by correlated multiplicative and additive noise 总被引:1,自引:0,他引:1
J. Wang L. Cao D.J. Wu 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):123-128
We present an analytic investigation of the signal-to-noise ratio (SNR) by studying the bistable sawtooth system driven by correlated Gaussian white noises. The analytic expression of SNR is obtained. Based on it, we detect the phenomenon of stochastic multiresonance, which arises from the dependence of SNR upon the noises correlation coefficient. Furthermore, there exists not only resonance, but also suppression in the SNR∼D (the additive noise intensity) curve and the SNR∼Q (the multiplicative noise intensity) curve.
Received 26 February 2002 / Received in final form 12 July 2002 Published online 17 September 2002 相似文献
8.
M. Feito F. J. Cao 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):63-68
Closed-loop or feedback controlled ratchets are
Brownian motors that operate using information about the state of
the system. For these ratchets, we compute the power output and
we investigate its relation with the information used in the
feedback control. We get analytical expressions for one-particle
and few-particle flashing ratchets, and we find that the maximum
power output has an upper bound proportional to the information.
In addition, we show that the increase of the power output that
results from changing the optimal open-loop ratchet to a
closed-loop ratchet also has an upper bound that is linear in the
information. 相似文献
9.
S. Aumaître A. Alastuey S. Fauve 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(2):263-266
Using simple scaling arguments and two-dimensional numerical simulations of a granular gas excited by vibrating one of the
container boundaries, we study a double limit of small 1-r and large L, where r is the restitution coefficient and L the size
of the container. We show that if the particle density n0 and (1-r2)(n0 Ld) where d is the particle diameter, are kept constant and small enough, the granular temperature, i.e. the mean value of
the kinetic energy per particle, 〈E 〉/N, tends to a constant whereas the mean dissipated power per particle, 〈D 〉/N, decreases
like
when N increases, provided that (1-r2)(n0 Ld)2 < 1. The relative fluctuations of E, D and the power injected by the moving boundary, I, have simple properties in that regime.
In addition, the granular temperature can be determined from the fluctuations of the power I(t) injected by the moving boundary. 相似文献
10.
M. Khorrami A. Aghamohammadi 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(3):223-227
A system of particles is studied in which the stochastic
processes are one-particle type-change (or one-particle diffusion)
and multi-particle annihilation. It is shown that, if the
annihilation rate tends to zero but the initial values of the
average number of the particles tend to infinity, so that the
annihilation rate times a certain power of the initial values of
the average number of the particles remain constant (the double
scaling) then if the initial state of the system is a
multi-Poisson distribution, the system always remains in a state
of multi-Poisson distribution, but with evolving parameters. The
large time behavior of the system is also investigated. The system
exhibits a dynamical phase transition. It is seen that for a
k-particle annihilation, if k is larger than a critical value
kc, which is determined by the type-change rates,
then annihilation does not enter the relaxation exponent of the
system; while for k < kc, it is the annihilation (in
fact k itself) which determines the relaxation exponent. 相似文献
11.
Solomon Fekade Mulugeta Bekele 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):369-374
We analyze the relaxation behavior of a bistable system when the background temperature profile is inhomogeneous due to the
presence of a localized hot region (blowtorch) on one side of the potential barrier. Since the diffusion equation for inhomogeneous
medium is model-dependent, we consider two physical models to study the kinetics of such system. Using a conventional stochastic
method, we obtain the escape and equilibration rates of the system for the two physical models. For both models, we find that
the hot region enhances the escape rate from the well where it is placed while it retards the escape rate from the other well. However, the value of the escape rate from the well where the hot region is placed differs
for the two models while that of the escape rate from the other well is identical for both. This work, for the first time,
gives a detailed report of the similarities and differences of the escape rates and, hence, exposes the common and distinct
features of the two known physical models in determining the way the bistable system relaxes.
Received 25 September 2001 相似文献
12.
S. Z. Ke D. J. Wu L. Cao 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(1):119-122
The colored noise problem is studied from the point of view of consistent Markovian approximations through extending unified
colored-noise approximation to the case of two-colored-noise driving systems. A bistable system simultaneously driven by multiplicative
and additive colored noise is investigated by means of the extended unified colored-noise approximation. It is found that,
for weak strength and color of the additive noise, the form of the stationary probability distribution changes from a unimodal
to a bimodal structure via a three modal one as the correlation time of the multiplicative colored noise increases, showing
the system undergoes a first order phase transition from a monostable to a bistable state. Numerical simulations support our
results.
Received 10 August 1998 and Received in final form 23 April 1999 相似文献
13.
D. Martila R. Mankin R. Tammelo A. Sauga E. Reiter 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(3):375-383
The influence of noise-flatness on overdamped motion of
Brownian particles in a 1D periodic system with a simple sawtooth
potential subjected to both unbiased thermal noise and
three-level telegraph noise is considered. The exact formula for
the stationary probability flux (current) is presented. The
phenomenon of multiple current reversals and some topological
properties of the hypersurface of zero current in the parameter
space of noises are investigated and illustrated by phase
diagrams. The conditions for the existence of four current
reversals versus the switching rate of nonequilibrium noise are
given. An alternative interpretation of the results in terms of
cross-correlation between two dichotomous noises is presented. 相似文献
14.
X. Gu S. Zhu D. Wu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):461-466
The steady state properties of a noise-driven bistable system are
investigated when there are two different kinds of time delays
existed in the deterministic and fluctuating forces respectively.
Using the approximation of the probability density approach, the
delayed Fokker-Planck equation is obtained. The stationary
probability distribution (SPD) and the variance of the system are
derived. It is found that the time delay τ in the deterministic
force can reduce the fluctuations while the time delay β in
the fluctuating force can enhance the fluctuations. Numerical
simulations are presented and are in good agreement with the
approximate theoretical results. 相似文献
15.
M. Ozer L. J. Graham 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):499-503
In a Hodgkin-Huxley neuron model driven just above threshold, external noise can increase both jitter and latency of the first
spike, an effect called “noise delayed decay” (NDD). This phenomenon is important when considering how neuronal information
is represented, thus by the precise timing of spikes or by their rate. We examine how NDD can be affected by network activity
by varying the model's membrane time constant, τm. We show that NDD is significant for small τm or high network activity, and decreases for large τm, or low network activity. Our results suggest that for inputs just above threshold, the activity of the network constrains
the neuronal coding strategy due to, at least in part, the NDD effect. 相似文献
16.
M. Dugic D. Rakovic 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(4):781-790
We investigate the quantum-mechanical tunneling between the “patterns" of the, so-called, associative neural networks. Being
the relatively stable minima of the “configuration-energy" space of the networks, the “patterns" represent the macroscopically
distinguishable states of the neural nets. Therefore, the tunneling represents a macroscopic quantum effect, but with some
special characteristics. Particularly, we investigate the tunneling between the minima of approximately equal depth, thus
requiring no energy exchange. If there are at least a few such minima, the tunneling represents a sort of the “random walk"
process, which implies the quantum fluctuations in the system, and therefore “malfunctioning" in the information processing
of the nets. Due to the finite number of the minima, the “random walk" reduces to a dynamics modeled by the, so-called, Pauli
master equation. With some plausible assumptions, the set(s) of the Pauli master equations can be analytically solved. This
way comes the main result of this paper: the quantum fluctuations due to the quantum-mechanical tunneling can be “minimized"
if the “pattern"-formation is such that there are mutually “distant" groups of the “patterns", thus providing the “zone" structure
of the “pattern" formation. This qualitative result can be considered as a basis of the efficient deterministic functioning
of the associative neural nets.
Received 15 July 1999 相似文献
17.
D.O. Kharchenko S.V. Kokhan 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):97-103
Within the power-law approach for noise amplitude dependence on stochastic variables, we present a picture of noise-induced
transitions in systems affected by coloured multiplicative noise. The governed equations for main statistical moments are
obtained and investigated in detail. We show that a reentrant noise-induced transition is realized within a window of the
control parameter.
Received 15 October 2001 / Received in final form 8 July 2002 Published online 17 September 2002 相似文献
18.
J.C. Gimel T. Nicolai D. Durand J.M. Teuler 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(1):91-97
Dynamic properties of Brownian particles immersed in a periodic potential with two barriers V1 and V2 (symmetric bistable potential) are studied by using the Fokker-Planck equation which we solve numerically by the matrix continued
fraction method. This study will therefore serve to demonstrate the influence of this form of potential, which is of great
interest for superionic conductors and for many other solid systems, on the diffusion process. Thus, we have calculated the
full width at half maximum (FWHM) ) of the quasi-elastic line of the dynamic structure factor, for a large range of values of the wave-vectors q. Our results show clearly that, by varying the ratio of the barriers strictly between and 1, the Fokker-Planck equation describes a diffusive process which has some characteristic of jump and
liquid-like regimes. While in the limit cases, i.e. when tends to or 1, the diffusion process can be described only by a simple jump motion. However, the jump-lengths corresponding
to each limit case are not equal. In general the change of the ratio is found to have a significant effect on the character
of the diffusive motion. We have also performed Fokker-Planck dynamics calculations of the diffusion coefficient in a bistable
potential. We have found a good agreement between numerical calculations and analytical approximation results obtained in
the high friction limit.
Received 25 May 1998 and Received in final form 15 November 1998 相似文献
19.
20.
R. M. D'Souza P. L. Krapivsky C. Moore 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(4):535-543
The “power of choice” has been shown to radically alter the behavior of a number of
randomized algorithms. Here we explore the effects of choice on models of random tree growth.
In our models each new node has k randomly chosen contacts, where k > 1 is a constant.
It then attaches to whichever one of these contacts is most desirable in some sense, such as its
distance from the root or its degree. Even when the new node has just two choices,
i.e., when k = 2, the resulting tree can be very different from a random graph or tree. For instance,
if the new node attaches to the contact which is closest to the root of the tree, the
distribution of depths changes from Poisson to a traveling wave solution.
If the new node attaches to the contact with the smallest degree, the degree distribution
is closer to uniform than in a random graph, so that with high probability there are no nodes in the
tree with degree greater than O(log log N). Finally, if the new node attaches to the contact
with the largest degree, we find that the degree distribution is a power law with exponent -1
up to degrees roughly equal to k, with an exponential cutoff beyond that; thus, in this case,
we need k ≫ 1 to see a power law over a wide range of degrees. 相似文献