共查询到20条相似文献,搜索用时 15 毫秒
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Both coherence resonance (CR) and stochastic resonance (SR) in a delayed bistable system driven by additive and multiplicative white noises and a weak harmonic excitation are studied by using the theory of two-state model. For the weak noise intensity and delayed feedback, the analytic expressions of power-spectrum and linear-spectrum amplification are derived to quantify the CR and the SR, respectively. The study shows that the peak in the power spectrum at the frequency corresponding to the time delay attains the maximum for an appropriate amount of additive noise intensity and the CR manifests. The feedback gain plays an important role in the SR. For example, the positive feedback gain enhances the SR, but the negative feedback gain suppresses the system output and makes the SR disappear. Moreover, the system also exhibits the frequency SR. 相似文献
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研究了基于关联噪声的带时滞项的非对称双稳系统的随机共振,在小时滞量及绝热近似理论下得到了信噪比的精确解析表达式,表明由于时滞量的存在系统出现了随机共振.讨论了系统的时滞量、噪声相关系数及系统的非对称性对系统的信噪比的影响. 相似文献
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The phenomenon of stochastic resonance is investigated in an asymmetric bistable system with coloured noises.The approximate Fokker-Planck equation is derived based on the Novikov theorem and the Fox approach.By applying the two-state theory,the expression of the signal-to-noise ratio is obtained in the adiabatic limit.The effects of the noise parameters on signal-to-ratio are discussed.It is found that the stochastic resonance phenomena appear in most cases and disappear in some special cases. 相似文献
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Stochastic resonance in with additive noises a stochastic bistable system and square-wave signal 下载免费PDF全文
<正>This paper considers the stochastic resonance in a stochastic bistable system driven by a periodic square-wave signal and a static force as well as by additive white noise and dichotomous noise from the viewpoint of signal-to-noise ratio.It finds that the signal-to-noise ratio appears as stochastic resonance behaviour when it is plotted as a function of the noise strength of the white noise and dichotomous noise,as a function of the system parameters,or as a function of the static force.Moreover,the influence of the strength of the stochastic potential force and the correlation rate of the dichotomous noise on the signal-to-noise ratio is investigated. 相似文献
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Lu-Chun Du 《Physica A》2010,389(6):1189-1933
A time-delayed tumor cell growth model with correlated noises is investigated. In the condition of small delay time, the stationary probability distribution is derived and the stationary mean value (〈x〉st) and normalized varianceλ2 of the tumor cell population and state transition rate (κ) between two steady states are numerically calculated. The results indicate that: (i) The delay time (τ) enhances the coherence resonance in 〈x〉st as a function of the multiplicative noise intensity (D) and increases 〈x〉st as a function of the additive noise intensity (α), i.e., τ enhances fluctuation of the system, however, the strength (λ) of correlations between multiplicative and additive noise plays a contrary role to τ on these; (ii) τ enhances the coherence resonance in κ as a function of D and increases κ as a function of α, i.e., τ speeds up the rate of state transition, however, λ also plays a contrary role to τ on these. 相似文献
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ZHANG HuiQing XU Wei XU Yong & ZHOU BingChang Department of Applied Mathematics Northwestern Polytechnical University Xi’an China 《中国科学:物理学 力学 天文学(英文版)》2010,(4)
The delay Fokker-Planck equation is given for an asymmetry bistable system with correlated Gaussian white noises. The small delay approximation based on the probability density approach is used and the approximate stationary probability density function is obtained. The phenomenon of delay induced transitions is found. When a weak periodic signal is added, the phenomenon of stochastic resonance is investigated. Expression of the signal-to-noise ratio (SNR) is obtained by using the two-state theory. It is sh... 相似文献
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Simulation study of the effects of time delay on the correlation function of a bistable system with correlated noises 下载免费PDF全文
<正>The effects of time delay on the fluctuation properties of a bistable system are investigated by simulating its normalised correlation function C(s).Three cases including linear delay,cubic delay and global delay in the system are considered respectively.The simulation results indicate that the linear delay enhances the fluctuation of the system (reduces the stability of the system) while the cubic delay and global delay weaken it(enforce the stability of the system),and the effect of cubic delay is more pronounced than the linear delay and global delay. 相似文献
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研究了乘性色噪声和加性白噪声驱动的光学双稳系统中噪声对系统两个方向平均首通时间T+(xs1→xs2)和T-(xs2→xs1)的影响(平均首通时间是指从一稳态出发越过势垒到另一稳态所用时间的平均值).通过Novikov定理和Fox近似方法得到相应的Fokker-Planck方程,利用最速下降法得到T+(xs1→xs2)和T-(xs2→xs1)的表达式.研究发现:乘性噪声强度Q和加性噪声强度D对T+(xs1→xs2)的影响相同,对T-(xs2→xs1)的影响不同;T+(xs1→xs2)随乘性色噪声自关联时间τ的增大而增大,但随噪声间的交叉关联强度λ的增大而减小;T-(xs2→xs1)随τ的增大而减小,随λ的增大而增大.
关键词:
平均首通时间
光学双稳系统
乘性色噪声
加性白噪声 相似文献
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Stochastic resonance (SR) induced by the bounded noise in an asymmetric bistable system is investigated. Based on stochastic simulation, the signal power amplification SPA is derived for the case of the additive modulated signal. The simulation results indicate that: (1) the SR phenomenon is weakened by the asymmetry of the system; (2) increasing the frequency ω restricts the SR of the system; (3) there is an optimum value of amplitude A matching the strongest SR phenomenon. 相似文献
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Stochastic resonance in an asymmetric bistable system driven by coloured correlated multiplicative and additive noise 下载免费PDF全文
This paper investigates the stochastic resonance (SR) phenomenon in an asymmetric system with coupling between multiplicative and additive noise when the coupling between two noise terms is coloured. The approximate expression of signal-to-noise ratio has been obtained by applying the two-state theory and SR exhibits in the bistable system. Moreover, the potential asymmetry r and cross-correlation strength λ can weaken the SR phenomenon, while the cross-correlation time r can strengthen the SR phenomenon. 相似文献
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The nonequilibrium phase transition and the symmetry revival induced by time delay in an asymmetric bistable system with correlated noises 下载免费PDF全文
The nonequilibrium phase transition and the symmetry
revival induced by time delay in a bistable system are investigated.
The stationary probability distribution function (SPDF) of the
bistable system with time delay and correlated noises are calculated
by an analytical method and stochastic simulation respectively. The
analytical and simulative results indicate that: (1) There is a
certain value of λ (λ denotes the strength of
correlations between the multiplicative and additive noises) to make
the SPDF symmetric under some time delay; however, above or below
the given value, the symmetry will be broken; (2) With the
monotonic change of λ , the unimodal peak structure of SPDF
becomes bimodal at the beginning, then it becomes unimodal again; this
means that there is a reentrance phenomenon in the process; (3)
There is a critical value of delay time, which makes the lower peak
of SPDF equal to the higher one under the critical condition. This
means that the symmetry revival phenomenon emerges. 相似文献
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We study the effects of correlations between quantum and pump noises on fluctuations
of the laser intensity in a saturation laser model. An approximative Fokker--Planck
equation and analytic expressions of the steady-state probability distribution
function (SPD) of the laser system are derived. Based on the SPD, the normalized
mean, the normalized variance, and the normalized skewness of the steady-state laser
intensity are calculated numerically. The results indicate that (i) the correlation
strength \lambda of correlated noises always enhances the fluctuation of laser
intensity; (ii) the correlation time \tau of correlated noises strengthens the
fluctuation of laser intensity for the below-threshold case but \tau weakens it
for the above-threshold case. 相似文献
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The effects of correlation between additive and multiplicative noises on the symmetry of an asymmetric bistable system are investigated. The steady-state probability distribution function of the system was calculated by using analytical and numerical methods. Results indicate that i) for the case of positive correlation between noises, as the correlation strength between additive and multiplicative noises, λ, increases, the symmetry of the system is restored; ii) for the case of negative correlation between noises, as the absolute value of λ increases, the symmetry of the system is destroyed; and iii) the analytic prediction agrees well with the stochastic simulation result. 相似文献
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The stationary correlation function and the associated relaxation time for a general system driven by cross-correlated white noises are derived, by virtue of a Stratonovich-like ansatz. The effects of correlated noises on the relaxation time of a bistable kinetic model coupled to an additive and a multiplicative white noises are studied. It is proved that for small fluctuations the relaxation time T_c as a function of λ (the correlated intensity between noises) exhibits very different behaviours for αD (α and D, respectively, stand for the ntensities of additive and multiplicative noises). When α>D, T_c increases with increasing λ. But when α相似文献
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研究了具有时滞反馈的非对称双稳系统中的振动共振现象. 在绝热近似条件下, 应用快慢变量分离法得到系统响应振幅的解析表达式Q, 分析了时滞参数α和不对称参数r对振动共振现象的影响. 结果表明: 在Q-α平台上, α可以诱导响应幅值的极大值以输入高频信号和低频信号的周期出现. 不对称参数并不影响共振发生的位置, 但是能够增强响应幅值. 在Q-B (B为高频信号振幅)平台上, 共振发生的位置BVR随着α呈现两种不同的周期关系, 且周期分别为输入高频信号和低频信号的周期. 在Q-Ω (Ω高频信号频率)平台上, 随着时滞参数的增大, 当B较小时, 在Ω的小值区间内, Q呈现出多重共振现象, 在Ω的大值区间, Q趋于定值. 相似文献