共查询到20条相似文献,搜索用时 648 毫秒
1.
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
2.
We consider the colored-noise-driven archetypal bistability dynamics of the Ginzburg-Landau type. The focus is on the stationary behavior and the problem of escape from metastable states. The deterministic flow of the underlyingtwo-variable Fokker-Planck process is studied as a function of the noise correlation time . As a main result we find that the separatrix exhibits a cusp at asymptotically large noise color. The stationary probability is evaluated approximately (unified colored noise approximation) and compared with numerical exact results. The stationary probability forms the key input in the evaluation of the rate of escape. At very strong noise color, the escape path closely follows a nodal line, passing through the corresponding stable node. The asymptotic result for the escape rate at large is compared with exact calculations for the lowest, nonvanishing eigenvalue. 相似文献
3.
In the case of T >> hω/k, by expanding the quasiparticle current power spectrum up to the third order term of hω/2kT, two noises are obtained: one is a white noise, the other is an O-U noise. We find that the two noises are the negative correlated noises, and correlation parameter λ is equal to -√6/3. Effects of the correlated noises on voltage-current characteristics curve are studied. The numerical computations show that the correlation parameter λ has very large effects on the voltage-current characteristics, but the correlation time τ of the O-U noise has a little effect. 相似文献
4.
研究了非高斯噪声激励下含周期信号的FHN模型的动力学行为. 通过计算神经元的平均响应时间、观察神经元的共振活化和噪声增强稳定现象,分析了非高斯噪声对神经元动力学行为的影响. 发现通过改变非高斯噪声的相关时间可以有效地改变共振活化和噪声增强稳定现象. 观察到在强相关噪声下不同强度的非高斯噪声抑制了神经元的噪声增强稳定现象而共振活化现象几乎不变,也就是非高斯噪声有效地增强了神经响应的效率. 观察了平均响应时间与非高斯噪声参数q之间的关系,当q为一个有限的小于1的值时,平均响应时间取得最小值. 最后表明在一定条件下,非高斯噪声出现重尺度现象,即非高斯噪声产生的效果可以由高斯白噪声来估计.
关键词:
FHN神经系统
非高斯噪声
平均响应时间
共振活化现象 相似文献
5.
Bernardo Spagnolo Angelo Carollo Davide Valenti 《The European physical journal. Special topics》2018,227(3-4):379-420
In this tutorial paper we present a comprehensive review of the escape dynamics from quantum metastable states in dissipative systems and related noise-induced effects. We analyze the role of dissipation and driving in the escape process from quantum metastable states with and without an external driving force, starting from a nonequilibrium initial condition. We use the Caldeira–Leggett model and a non-perturbative theoretical technique within the Feynman–Vernon influence functional approach in strong dissipation regime. In the absence of driving, we find that the escape time from the metastable region has a nonmonotonic behavior versus the system-bath coupling and the temperature, producing a stabilizing effect in the quantum metastable system. In the presence of an external driving, the escape time from the metastable region has a nonmonotonic behavior as a function of the frequency of the driving, the thermal-bath coupling and the temperature. The quantum noise enhanced stability phenomenon is observed in both systems investigated. Finally, we analyze the resonantly activated escape from a quantum metastable state in the spin-boson model. We find quantum stochastic resonant activation, that is the presence of a minimum in the escape time as a function of the driving frequency. Background and introductory material has been added in the first three sections of the paper to make this tutorial review reasonably self-contained and readable for graduate students and non-specialists from related areas. 相似文献
6.
The overdamped motion of a Brownian particle in randomly switching piece-wise metastable linear potential shows noise enhanced stability (NES): the noise stabilizes the metastable system and the system remains in this state for a longer time than in the absence of white noise. The mean first passage time (MFPT) has a maximum at a finite value of white noise intensity. The analytical expression of MFPT in terms of the white noise intensity, the parameters of the potential barrier, and of the dichotomous noise is derived. The conditions for the NES phenomenon and the parameter region where the effect can be observed are obtained. The mean first passage time behaviors as a function of the mean flipping rate of the potential for unstable and metastable initial configurations are also analyzed. We observe the resonant activation phenomenon for initial metastable configuration of the potential profile.Received: 16 June 2004, Published online: 31 August 2004PACS:
05.40.-a Fluctuation phenomena, random processes, noise, and Brownian motion - 02.50.-r Probability theory, stochastic processes, and statistics - 05.10.Gg Stochastic analysis methods (Fokker-Planck, Langevin, etc.) 相似文献
7.
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
8.
The mean first-passage time of a bistable system with time-delayed feedback driven by multiplicative non-Gaussian noise and additive Gaussian white noise is investigated. Firstly, the non-Markov process is reduced to the Markov process through a path-integral approach; Secondly, the approximate Fokker-Planck equation is obtained by applying the unified coloured noise approximation, the small time delay approximation and the Novikov Theorem. The functional analysis and simplification are employed
to obtain the approximate expressions of MFPT. The effects of non-Gaussian
parameter (measures deviation from Gaussian character) r, the delay
time τ, the noise correlation time
τ0, the intensities D and α of noise on the MFPT are discussed. It is found
that the escape time could be reduced by increasing the delay time τ,
the noise correlation time τ0, or by reducing the
intensities D and α. As far as we know, this is the first time to
consider the effect of delay time on the mean first-passage time in the
stochastic dynamical system. 相似文献
9.
本文研究了时间延迟对Logistic系统从亚稳态跃迁到稳定态的跃迁率的影响. 假设在细胞演化过程中细胞衰减存在时间延迟,利用小延迟时间条件下一阶近似方法和最陡下降法导出了系统的跃迁率解析式. 数值计算结果表明,内噪声,外噪声和内外噪声之间的关联促使系统从亚稳态跃迁到稳定态, 而时间延迟阻碍了系统从亚稳态到稳定态的跃迁, 即时间延迟增强了系统亚稳态的稳定性.
关键词:
Logistic模型
跃迁率
时间延迟
噪声 相似文献
10.
11.
G. Augello D. Valenti A. L. Pankratov B. Spagnolo 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(1):145-151
We study the transient statistical properties of short and long Josephson junctions under the influence of thermal and correlated
fluctuations. In particular, we investigate the lifetime
of the superconductive metastable state finding the presence of noise induced phenomena. For short Josephson junctions we
investigate the lifetime as a function both of the frequency of the current driving signal and the noise intensity and we
find how these noise-induced effects are modified by the presence of a correlated noise source. For long Josephson junctions
we integrate numerically
the sine-Gordon equation calculating the lifetime as a function of the length of the junction both for inhomogeneous and homogeneous
bias current distributions. We obtain a non-monotonic behavior of the lifetime as a function of the frequency of the current
driving signal and the correlation time of the noise. Moreover we find two maxima in the non-monotonic behaviour of the mean
escape time as a
function of the correlated noise intensity. 相似文献
12.
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
13.
The Hamilton-Jacobi theory in nonpotential systems developed by Maier and Stein is applied to colored noise-driven systems. The behavior of the most probable escape path (MPEP) is discussed. Singularity occurs for the MPEP in the large correlation time τ limit, which is closely related to the well-known probability hole problem. The solution along the MPEP is derived. The behavior near the fixed point is analyzed, and a critical value τc, is found, which is in agreement with that obtained by other authors. 相似文献
14.
Iwaniszewski J Kaufman IK McClintock PV McKane AJ 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(2):1170-1175
Electronic analog experiments on escape over a fluctuating potential barrier are performed for the case when the fluctuations are caused by Ornstein-Uhlenbeck noise (OUN). In its dependence on the relation between the two OUN parameters (the correlation time tau and noise strength Q) the nonmonotonic variation of the mean escape time T as a function of tau can exhibit either a minimum (resonant activation), or a maximum (inhibition of activation), or both these effects. The possible resonant nature of these features is discussed. We claim that T is not a good quantity to describe the resonancelike character of the problem. Independently of the specific relation between the OUN parameters, the resonance manifests itself as a maximal lowering of the potential barrier during the escape event, and it appears for tau of the order of the relaxation time toward the metastable state. 相似文献
15.
The asymmetric effects on the escape rates from the stable states x± in the bistable system are analyzed. The results indicate that the multiplicative noise and the additive noise always enhance the particle escape from stable states x± of bistable. However, the asymmetric parameter r enhances the
particle escape from stable state x+, and holds back the particle escape from stable state x-. 相似文献
16.
Zheng-Lin Jia 《Physica A》2008,387(25):6247-6251
The effects of time delay on the transient properties of a time-delayed metastable system subjected to cross-correlated noises are studied by means of a stochastic simulation method. It is found that: (i) Both additive noise and multiplicative noise can produce the noise enhanced stability (NES) effect; (ii) The time delay induces critical behavior on the NES, i.e., there is a critical value of the delay time τc1≈2.2, above which the time delay increases the stability of the system enhanced by the additive noise, and below which the NES effect induced by the additive noise disappears; (iii) There exists another critical value of the delay time τc2≈3.0, above which the time delay increases the stability of the system enhanced by the multiplicative noise and below which the time delay decreases it. 相似文献
17.
HAN Qing-Lin ZENG Jia-Kui YANG Tao ZHANG Chun LONG Fei FU Yun-Chang ZENG Chun-Hua 《理论物理通讯》2015,64(2):151-158
In this paper, we investigate the stationary probability distribution and mean first passage time in a vegetation ecological system, which is driven by cross-correlation between intrinsic and extrinsic colored noises as well as the nonzero cross-correlation in between. The impacts of the self-correlation time τ1 and τ2, the cross-correlation time τ3 and intensity k on the stationary probability distribution and mean first passage time are discussed, respectively. Our main results show that: (#em/em#) the self-correlation time τ1 can induce regime shifts from the desert state to the sustainable vegetation state, while the self-correlation time τ2, cross-correlation time τ3 and intensity k can induce regime shifts from the sustainable vegetation state to the desert state; and (ii) the self-correlation time τ1 or τ2 can enhance the stability of the sustainable vegetation biomass, while the cross-correlation time τ3 or strength k weakens the stability of the sustainable vegetation biomass. 相似文献
18.
19.
A stochastic differential equation driven by N-order nonlinear fluctuation is investigated by defining a novel stochastic process Г(t). The spectral densities of Г(t) for N = 1,2,3 and 4 are obtained. We compare the results of the linear fluctuation case with the nonlinear fluctuation case and find that the extremum of the spectral density for linear case is directly proportional to the noise intensity D and independent of the correlation time τ, the extremum of the spectral density for nonlinear case is determined by both D and τ. An approximate Fockker-Planck equation of the N-order nonlinear fluctuation is derived by Hanggi-like ansatz. The infl uences of nonlinear fluct uation on the transition of bistable system are studied. It is found that the area of unimodal region and bimodal region of the stationary probability is independent of D and τ for linear case, however, the area of two regions is related to D and τ for nonlinear case. 相似文献
20.
本文主要研究了关联乘性非高斯噪声和加性高斯白噪声共同激励的FHN(Fitz Hugh-Nagumo)神经元系统.利用路径积分法和统一色噪声近似,推导出该系统的定态概率密度函数表达式.通过研究发现,乘性噪声强度D、加性噪声强度Q、噪声自关联时间τ以及互关联系数λ均可以诱导系统产生非平衡相变现象,而非高斯参数q却不可以诱导系统产生非平衡相变现象.此外,我们还发现参数D和λ的增大有利于神经元系统从激发态向静息态转换,Q和τ的增大有利于神经元系统从静息态向激发态转换,q的增大会使得神经元系统停留在静息态的概率增加. 相似文献