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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
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We study two models for Josephson junctions, i.e.,a Gaussian white noise model and a symmetric dichotomous noises model. In this study we find that the correlated symmetric noises can produce a net voltage. This phenomenon is due to the correlation between the additive and the multiplicative noises. We show some characteristic features for this phenomenon: the net voltage is always negative and has a peak value when the strength of the additive noises varies for the former model(or when the strengths of the noises vary for the latter model). The results provide a theoretical foundation for reducing the net voltage caused by the correlated symmetric noises. 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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噪音关联对单模激光光强定态几率分布的影响 总被引:1,自引:1,他引:0
从理论上对加性白噪音和乘性色噪音之间存在关联作用的单模激光立方模型进行了分析.通过数值计算得到;噪音关联时间和噪音关联强度参量对光强定态几率分布曲线有很大影响;特别地,当两噪音之间存在完全负关联时,光强被锁定在某一固定值处. 相似文献
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X.-M. Zhang B.-Q. Ai 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,73(3):433-437
We study the steady state properties of a genotype selection model in the presence of two time correlated Gaussian white noises.
Based on the corresponding Fokker-Planck equation the steady state solution of the probability distribution has been investigated.
The fluctuation of both the mutation factor and the genetic factor can break the balance of the gene selection. The fluctuation
of the genetic factor can facilitate the gene separation which allows us to select one gene-type haploid from a gene group
while the fluctuation of the mutation factor impedes the gene separation. Remarkably, the correlation time between the two
noises can induce the system to change from two states to one. 相似文献
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This paper deals with systems driven by correlated colored noises. The evolution equations for both the single and joint probability distribution functions are derived. It is shown that both the stationary and dynamical properties of the systems are affected by correlated colored noises. These results are obtained by means of the systematic use of the ordered cumulant-expansion technique. 相似文献
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An experiment was performed to study the interaction of two narrow-band noises having correlated temporal envelopes. The detection threshold of a 100-Hz-wide noise-band signal was measured at different center frequencies in the presence of a continuous 100-Hz-wide noise band having a center frequency of 1000 Hz. The two noise bands had either correlated or independent temporal envelopes. Measured signal detection thresholds are lower when the two noise bands are independent, but the magnitude of this difference is not a simple function of the frequency separation between the two noise bands. 相似文献
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Transport of an inertial Brownian motor moving in an asymmetric periodic potential driven by an external force and correlated noises is investigated. Using the numerical algorithm, the asymptotic mean velocity (AMV) for characterizing directed transport is obtained. The effects of the external driving force f and the correlation λ between the two noises on the AMV are discussed. The results manifest: (1) the external driving force and the correlation between the two noises can lead to the phenomena like current reversal. (2) The competitions among the external driving force and the correlation between the two noises are necessary for current reversal, i.e., fλ>0. (3) Different directions of transport are found for different masses of the Brownian particles under the condition fλ>0. Therefore a theoretical study is suggested for separating Brownian particles according to their different masses in the ratchet system. 相似文献
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B.-Q. Ai H. Zheng L.-G. Liu 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(3):373-376
We study the steady state properties of an absorptive
optical bistable model in the presence of correlated noises.
Based on the corresponding Fokker-Planck equation the steady state
solution of the probability distribution and the average value of
the transmitted light have been investigated. We have found that
fluctuations of the input light amplitude improve the transmitted
light and an optimized value exists for the fluctuations of the
population difference at which the transmitted light takes its
maximum value. The correlation between the two noises reduce the
transmitted light and the noises in the model can induce a phase transition. 相似文献
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研究了加性噪声和乘性噪声共同驱动的双稳态系统中的随机共振和相干共振现象. 针对加性噪声和乘性噪声之间不存在关联性和存在关联性两种情形, 引入一种适当的能同时表征随机共振和相干共振的指标, 应用一阶欧拉方法, 通过数值模拟对系统的随机共振和相干共振现象进行研究. 结果表明在弱噪声驱动下, 随着加性噪声强度的增加, 当系统出现相干共振时, 如果给系统外加一个弱周期驱动力, 几乎在同一时刻, 系统也出现了随机共振现象; 但随着乘性噪声强度的增加, 仅当加性噪声和乘性噪声之间相关时, 此结论成立. 并且系统参数对相干共振和随机共振的影响是一致的.
关键词:
双稳态系统
随机共振
相干共振 相似文献
16.
Current transport and mass separation for an asymmetric fluctuation system with correlated noises
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We discuss the transport of an underdamped particle driven by an external fluctuation force in a spatially periodic asymmetric potential with correlated noises. The corresponding mathematical model is established. The movement of the steady current of an underdamped particle is presented by the method of the numerical simulation. It is indicated that the value of the current may be negative, zero, or positive. The external fluctuation force and correlated noises can effect the current direction. Under the appropriate parameters, the correlated noises intensity may even raise a reversal of the current.Besides, we have noticed a phenomenon that particles with different weight have different directions during movement by the impact of the correlated noises and external fluctuation force. Therefore, the Brownian particles can be effectively separated according to their masses. 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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We have derived exact expressions for the correlation function, power spectrum and correlation time of a one-dimensional non-Markovian linear system driven by correlated noises with correlation forms of delta function and different-time-region exponential function, respectively. We find that these dynamic properties of system for delta form are much different from those for different-time-region exponential form. Especially, the power spectrum for the former only has one peak but for the latter can have one, two or three peaks. 相似文献
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We present a detailed study of the transport and the efficiency of a ratchet system in a periodic potential in the presence of correlated noises. The current and the efficiency of the system are investigated. It is found that, when the potential is spatially symmetric, the correlation between the two noises can induce a net transport. The efficiency shows many interesting features as a function of the applied force, the noise intensity, the external load, etc. The efficiency can be maximized as a function of noise intensity (or temperature), which shows that the thermal fluctuation can facilitate the efficiency of energy transformation. 相似文献
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The Stratonovich stochastic differential equation is used to analyze genotype selection in the presence ot correlatecl Gaussian white noises. We study the steady state properties of the genotype selection and discuss the effects of the correlated noises. It is found that the degree of correlation of the noises can be used to select one type of genes from another type of mixing genes. The strong selection of genes caused by a large value of multiplicative noise intensity can be weakened by the intensive negative correlation. 相似文献