共查询到20条相似文献,搜索用时 31 毫秒
1.
B. Spagnolo A. Dubkov 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):299-303
The one-dimensional overdamped Brownian motion in a symmetric
periodic potential modulated by external time-reversible noise is
analyzed. The calculation of the effective diffusion coefficient
is reduced to the mean first passage time problem. We derive
general equations to calculate the effective diffusion coefficient
of Brownian particles moving in arbitrary supersymmetric potential
modulated by: (i) an external white Gaussian noise and (ii) a
Markovian dichotomous noise. For both cases the exact expressions
for the effective diffusion coefficient are derived. We obtain
acceleration of diffusion in comparison with the free diffusion
case for fast fluctuating potentials with arbitrary profile and
for sawtooth potential in case (ii). In this case the parameter
region where this effect can be observed is given. We obtain also
a finite net diffusion in the absence of thermal noise. For
rectangular potential the diffusion slows down, for all parameters
of noise and of potential, in comparison with the case when
particles diffuse freely. 相似文献
2.
K. Mallick P. Marcq 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(4):553-561
We study analytically and numerically the problem of a nonlinear mechanical oscillator with additive noise in the absence
of damping. We show that the amplitude, the velocity and the energy of the oscillator grow algebraically with time. For Gaussian
white noise, an analytical expression for the probability distribution function of the energy is obtained in the long-time
limit. In the case of colored, Ornstein-Uhlenbeck noise, a self-consistent calculation leads to (different) anomalous diffusion
exponents. Dimensional analysis yields the qualitative behavior of the prefactors (generalized diffusion constants) as a function
of the correlation time.
Received 10 October 2002 Published online 6 March 2003
RID="a"
ID="a"e-mail: mallick@spht.saclay.cea.fr 相似文献
3.
G. Bonanno D. Valenti B. Spagnolo 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(3):405-409
We study a generalization of the Heston model, which consists of
two coupled stochastic differential equations, one for the stock
price and the other one for the volatility. We consider a cubic
nonlinearity in the first equation and a correlation between the
two Wiener processes, which model the two white noise sources.
This model can be useful to describe the market dynamics
characterized by different regimes corresponding to normal and
extreme days. We analyze the effect of the noise on the
statistical properties of the escape time with reference to the
noise enhanced stability (NES) phenomenon, that is the noise
induced enhancement of the lifetime of a metastable state. We
observe NES effect in our model with stochastic volatility. We
investigate the role of the correlation between the two noise
sources on the NES effect. 相似文献
4.
O.V. Gerashchenko S.L. Ginzburg M.A. Pustovoit 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(1):101-106
Recently we discovered the phenomenon of hypersensitivity to small time-dependent signals in a simple stochastic system, the
Kramers oscillator with multiplicative white noise. In the present work we study, theoretically and experimentally with analog
simulations, an influence of noise correlation time on hypersensitivity in a nonlinear oscillator with piecewise-linear current-voltage
characteristic and multiplicative colored dichotomous noise. We found that the region of hypersensitive behavior is defined
by universal scaling index, whereas the specifics of a particular system reveals itself only in the dependence of the above
index on system parameters. The dependence of gain factor on noise correlation time is of bell-shaped (resonant) type.
Received 27 April 2000 and Received in final form 2 November 2000 相似文献
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7.
The associated relaxation time and the intensity correlation function of a bistable system driven by an additive and a multiplicative
coloured noise with coloured cross-correlation are investigated. Using the Novikov theorem and the projection operator method,
the analytic expressions of the stationary probability distribution Pst(x), the relaxation time Tc, and the normalized correlation function C(s) of the system are obtained. The effects of the noise intensity, the cross-correlation
strength λ and the cross-correlation time τ are discussed. By numerical computation, it is found that the cross-correlation
strength |λ| and the quantum noise intensity D decrease the relaxation of the system from unstable points. The cross-correlation
time τ delays relaxation of the system from unstable points. The cross-correlation strength λ and the cross-correlation time
τ can alter the effects of the pump noise intensity Q. Thus, the relaxation time Tc is a stochastic resonant phenomenon, and distribution
curves exhibit a single-maximum structure. 相似文献
8.
C.W. Xie D.C. Mei L. Cao D.J. Wu 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(1):83-86
The relative escape rate (RER) for Brownian particles in an asymmetric bistable sawtooth potential driven by cross correlations
between multiplicative white noise and additive white noise is studied. A new expression of the mean first-passage time is
derived under the condition of piecewise linear potentials and discontinuous diffusion function. Based on the results of RER
numerically calculated, it is found that (i) under positively correlated noises action (i.e. λ > 0, and λ is the correlation strength), the escape rate exhibits the suppression platform as the intensity of multiplicative
noise varies. The effect of suppression becomes more pronounced with the growth of height of the deterministic potential barrier
for transition, and with the increase of λ. However, for the case of uncorrelated noises (λ = 0) and of negatively correlated
noises (λ < 0), the suppression platform disappears. (ii) The positive correlation between noises amplifies the change of
the escape rate with the height of barrier for transition, while the negative correlation between noises suppresses this change.
Received 20 November 2002 / Received in final form 19 October 2003 Published online 23 May 2003
RID="a"
ID="a"e-mail: kmdcmei@public.km.yn.cn 相似文献
9.
L. Borland F. Pennini A.R. Plastino A. Plastino 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(2):285-297
Nonlinear Fokker-Planck equations (e.g., the diffusion equation for porous medium) are important candidates for describing anomalous diffusion in a variety of systems.
In this paper we introduce such nonlinear Fokker-Planck equations with general state-dependent diffusion, thus significantly
generalizing the case of constant diffusion which has been discussed previously. An approximate maximum entropy (MaxEnt) approach
based on the Tsallis nonextensive entropy is developed for the study of these equations. The MaxEnt solutions are shown to
preserve the functional relation between the time derivative of the entropy and the time dependent solution. In some particular
important cases of diffusion with power-law multiplicative noise, our MaxEnt scheme provides exact time dependent solutions. We also prove that the stationary solutions of the nonlinear Fokker-Planck equation with diffusion
of the (generalized) Stratonovich type exhibit the Tsallis MaxEnt form.
Received 26 February 1999 相似文献
10.
D. Valenti G. Augello B. Spagnolo 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(3):443-451
We analyze the dynamics of the FitzHugh-Nagumo (FHN) model in the presence of colored noise and a periodic signal. Two cases
are considered: (i) the dynamics of the membrane potential is affected by the noise, (ii) the slow dynamics of the recovery
variable is subject to noise. We investigate the role of the colored noise on the neuron dynamics by the mean response time
(MRT) of the neuron. We find meaningful modifications of the resonant activation (RA) and noise enhanced stability (NES) phenomena
due to the correlation time of the noise. For strongly correlated noise we observe suppression of NES effect and persistence
of RA phenomenon, with an efficiency enhancement of the neuronal response. Finally we show that the self-correlation of the
colored noise causes a reduction of the effective noise intensity, which appears as a rescaling of the fluctuations affecting
the FHN system. 相似文献
11.
M. L. Deng W. Q. Zhu 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(3):391-397
The energy diffusion controlled reaction rate of a reacting particle with linear weak damping and broad-band noise excitation
is studied by using the stochastic averaging method. First, the stochastic averaging method for strongly nonlinear oscillators
under broad-band noise excitation using generalized harmonic functions is briefly introduced. Then, the reaction rate of the
classical Kramers' reacting model with linear weak damping and broad-band noise excitation is investigated by using the stochastic
averaging method. The averaged It? stochastic differential equation describing the energy diffusion and the Pontryagin equation
governing the mean first-passage time (MFPT) are established. The energy diffusion controlled reaction rate is obtained as
the inverse of the MFPT by
solving the Pontryagin equation. The results of two special cases of
broad-band noises, i.e. the harmonic noise and the exponentially corrected noise, are discussed in details. It is demonstrated
that the general expression of reaction rate derived by the authors can be reduced to the classical ones via linear approximation
and high potential barrier approximation. The good agreement with the results of the Monte Carlo simulation verifies that
the reaction rate can be well predicted using the stochastic averaging method. 相似文献
12.
用n阶时间导数噪声作为内部热噪声驱动自由粒子运动时,若该噪声所对应的非各态历经强度b?=0,且系统初始处于热平衡,则此时系统的长时稳态速度可以作为非各态历经噪声使用.非各态历经噪声具有谱密度在零频处发散的特点,一维半无界耦合简谐振子链对与之相连的气体分子的作用具有非各态历经噪声的特点,是非各态历经噪声的实例.最后将非各态历经噪声作为外噪声驱动倾斜周期势中的粒子运动,系统出现扩散指数α2的超弹道扩散现象.同时发现系统的速度分布将呈现出迁移态和锁定态两种不同状态,并且处于迁移态的粒子的速度分布为双峰.迁移态中双峰的出现是一种比较新奇的现象. 相似文献
13.
We study the phenomenon of stochastic resonance on
small-world networks consisting of bistable genetic regulatory units,
whereby the external subthreshold periodic forcing is introduced as a
pacemaker trying to impose its rhythm on the whole network through the
single unit to which it is introduced. Without the addition of additive
spatiotemporal noise, however, the whole network remains forever trapped in
one of the two stable steady states of the local dynamics. We show that the
correlation between the frequency of subthreshold pacemaker activity and the
response of the network is resonantly dependent on the intensity of additive
noise. The reported pacemaker driven stochastic resonance depends
significantly on the asymmetry of the two potential wells characterizing the
bistable dynamics, which can be tuned via a single system parameter. In
particular, we show that the ratio between the clustering coefficient and
the characteristic path length is a suitable quantity defining the ability
of a small-world network to facilitate the outreach of the pacemaker-emitted
subthreshold rhythm, but only if the asymmetry between the potentials is
practically negligible. In case of substantially asymmetric potentials the
impact of the small-world topology is less profound and cannot warrant an
enhancement of stochastic resonance by units that are located far from the
pacemaker. 相似文献
14.
A bistable system with noise and time delay is investigated. Theoretical analysis and stochastic simulation show that: (i) In the ease of a system driven only by multiplicative Gaussian white noise, the mean first-passage time for a particle to reach the other stable state from one stable state exhibits a minimum with respect to delay time, i.e., a resonant-like activation (RA) phenomenon. (ii) In the action of additive and multiplicative noise, as the additive noise intensity increases, no matter whether a correlation between the two types of noise exists or not, the RA gradually disappears. (iii) The correlation strength between the two types of noise does not influence the existence of the RA. 相似文献
15.
E. V. Pankratova V. N. Belykh E. Mosekilde 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(4):529-536
The present paper examines the influence of the forcing frequency on the
response of a randomly perturbed Hodgkin-Huxley system in the realm
of suprathreshold amplitudes. Our results show that, in the presence
of noise, the choice of driving frequency can seriously affect the
precision of the external information transmission. At the same
level of noise the precision can either decrease or increase
depending on the driving frequency. We demonstrate that the
destructive influence of noise on the interspike interval can be
effectively reduced. That is, with driving signals in certain
frequency ranges, the system can show stable periodic spiking even
for relatively large noise intensities. Here, the most accurate
transmission of an external signal occurs. Outside these frequency
ranges, noise of the same intensity destroys the regularity of the
spike trains by suppressing the generation of some spikes. On the
other hand, we show that noise can have a reconstructive role for
certain driving frequencies. Here, increasing noise intensity
enhances the coherence of the neuronal response. 相似文献
16.
Yong Woon Parc Duk-Su Koh Wokyung Sung 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(1):127-131
Stochastic resonance (SR) is a novel cooperative phenomenon occurring in
nonlinear systems due to coupling of an ambient noise and an external
signal. Biological systems may use SR mechanism to detect the signal
efficiently from an external environment. A number of studies have addressed
the SR in artificial ion channels considering external voltages as noises.
More important than these external noises is the internal, thermal noise
which changes the channel conformations essential for biological functions.
In this work, we consider that the channel gating rates follow a
non-Arrhenius temperature dependence derived from experimental data of a
real biological channel. Using the Monte-Carlo simulations, we find that in
this channel SR occurs near a physiological temperature in a very
distinctive manner compared with that for the Arrhenius gating model. 相似文献
17.
We present an analytical study of a nonlinear oscillator subject to an additive Ornstein–Uhlenbeck noise. Known results are mainly perturbative and are restricted to the large dissipation limit (obtained by neglecting the inertial term) or to a quasi-white noise (i.e., a noise with vanishingly small correlation time). Here, in contrast, we study the small dissipation case (we retain the inertial term) and consider a noise with finite correlation time. Our analysis is non perturbative and based on a recursive adiabatic elimination scheme a reduced effective Langevin dynamics for the slow action variable is obtained after averaging out the fast angular variable. In the conservative case, we show that the physical observables grow algebraically with time and calculate the associated anomalous scaling exponents and generalized diffusion constants. In the case of small dissipation, we derive an analytic expression of the stationary probability distribution function (PDF) which differs from the canonical Boltzmann–Gibbs distribution. Our results are in excellent agreement with numerical simulations. 相似文献
18.
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
19.
利用有和无外信号作用的脉孢菌生物钟体系,研究了与加性噪音相关或不相关的乘性噪音对加性噪音诱导出的内信号随机共振的影响作用.结果表明:无外信号的情况下,不论加性和乘性噪音相关与否,当乘性噪音强度小于临界值时,乘性噪音的加入使加性噪音诱导产生的内随机共振强度得到增强;当大于其临界值时,加性噪音的随机共振强度却得不到进一步增强,这说明脉孢菌生物钟体系能抵抗外噪音的干扰而维持自身的生理节奏.当加入外信号时,对于乘性和加性噪音不相关的情况,发现存在最佳频率(0.003 Hz)的外信号能使加性噪音诱导出的内信号随机共
关键词:
噪音
脉孢菌生物钟体系
内信号随机共振 相似文献
20.
S. I. Denisov W. Horsthemke P. H?nggi 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,68(4):567-575
We derive the generalized Fokker-Planck equation associated with the
Langevin equation (in the Ito sense) for an overdamped particle in an external
potential driven by multiplicative noise with an arbitrary distribution of the
increments of the noise generating process. We explicitly consider this
equation for various specific types of noises, including Poisson white noise
and Lévy stable noise, and show that it reproduces all Fokker-Planck
equations that are known for these noises. Exact analytical, time-dependent and
stationary solutions of the generalized Fokker-Planck equation are derived and
analyzed in detail for the cases of a linear, a quadratic, and a tailored
potential. 相似文献