Search

Through theoretical analysis and numerical simulation, we investigate ratchet effect of active particles in biased velocity potential in the presence of cross-correlated noises. For a single active particle, the mean velocity and mobility suggest that cross-correlated noises can lead to the ratchet effect. The finding is interpreted by the time series, the rectified potential, mean square displacement, and the diffusion coefficient. The diffusion displays hyperdiffusion, superdiffusion, and normal diffusion for different conditions and time intervals. The crossover times that separates these stages can be controlled by cross-correlated noises and static force. For interacting active particles, we find through time series and average velocity that the weak interaction between particles, which leads to weak collective motion, can enhance the ratchet effect. However, the strong interaction, which results in strong collective motion, can weaken, even eliminate it. Our results may provide a valuable way to control the transport of active particles through the ratchet effect. [ABSTRACT FROM AUTHOR]

The phenomenon of stochastic resonance (SR) in a tumor growth model under the presence of immune surveillance is investigated. Time delay and cross-correlation between multiplicative and additive noises are considered in the system. The signal-to-noise ratio (SNR) is calculated when periodic signal is introduced multiplicatively. Our results show that: (i) the time delay can accelerate the transition from the state of stable tumor to that of extinction, however the correlation between two noises can accelerate the transition from the state of extinction to that of stable tumor; (ii) the time delay and correlation between two noises can lead to a transition between SR and double SR in the curve of SNR as a function of additive noise intensity, however for the curve of SNR as a function of multiplicative noise intensity, the time delay can cause the SR phenomenon to disappear, and the cross-correlation between two noises can lead to a transition from SR to stochastic reverse-resonance. Finally, we compare the SR phenomenon for the multiplicative periodic signal with that for additive periodic signal in the tumor growth model with immune surveillance. [ABSTRACT FROM AUTHOR]

Abstract: The effects of noise and time-delayed feedback in the dimer–monomer (DM) surface reaction model are investigated. Applying small delay approximation, we construct a stochastic delayed differential equation and its Fokker–Planck equation to describe the state evolution of the DM reaction model. We show that the noise can only induce first-order irreversible phase transition (IPT) characteristic of the DM model, however the combination of the noise and time-delayed feedback can simultaneously induce first- and second-order IPT characteristics of the DM model. Therefore, it is shown that the well-known first- and second-order IPT characteristics of the DM model may be viewed as noise-and delay-induced phase transitions. [Copyright &y& Elsevier]

Transport and diffusion of Brownian particles in a symmetrical periodic potential were investigated for both overdamped and underdamped cases, where the ratchet potential is driven by an external unbiased time periodic force and correlation between thermal and potential fluctuations. It is shown that the correlation between two noises breaks the symmetry of the potential to generate motion of the Brownian particles in particular direction, and the current can reverse its direction by changing the sign of the noise correlation. For the overdamped case, the systemic parameters only induce the directed current, and the noise correlation suppresses the diffusion of the overdamped Brownian particles. However for the underdamped case, the current reverses its direction multiple times with increasing the systemic parameters, i.e., the multiple current reversal is observed, and the noise negative correlation suppresses the diffusion of the underdamped Brownian particles, while the noise positive correlation enhances it. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the role of correlated multiplicative ( κ 1 ) and additive ( κ 2 ) noises in a modified energy conversion depot model, at which it is added a linear term in the conversion of internal energy of active Brownian particles (ABPs). The linear term ( a 1 ≠ 0 . 0 ) in energy conversion model breaks the symmetry of the potential to generate motion of the ABPs with a net transport velocity. Adopt a nonlinear Langevin approach, the transport properties of the ABPs have been discussed, and our results show that: (i) the transport velocity 〈 υ 1 〉 of the ABPs are always positive whether the correlation intensity λ = 0 . 0 or not; (ii) for a small value of the multiplicative noise intensity κ 1 , the variation of 〈 υ 1 〉 with λ shows a minimum, there exists an optimal value of the correlation intensity λ at which the 〈 υ 1 〉 of the ABPs is minimized. But for a large value of κ 1 , the 〈 υ 1 〉 monotonically decreases; (iii) the transport velocity 〈 υ 1 〉 increases with the increase of the κ 1 or κ 2 , i.e., the multiplicative or additive noise can facilitate the transport of the ABPs; and (iv) the effective diffusion increases with the increase of a 1 , namely, the linear term in modified energy conversion model of the ABPs can enhance the diffusion of the ABPs. [ABSTRACT FROM AUTHOR]

We investigate the transport properties of active Brownian particle (ABP) in the Schweitzer–Ebeling–Tilch (SET) model, driven by cross-correlation between multiplicative and additive noises and a bias force. It is shown that (i) the cross-correlated noises and bias force can lead to a transition from bimodal to unimodal, and the numerical simulations are in good agreement with the theoretical results; (ii) the cross-correlated noises and bias force can enhance the transport and weaken the diffusion of the ABP; (iii) the multiplicative noise can facilitate the transport and enhance the diffusion of the ABP, and a giant diffusion by a larger multiplicative noise, whereas the additive noise can weaken the transport of the ABP. A physical mechanism for the transport and diffusion of the ABP is derived from the effective velocity potential for the above findings; and (iv) the cross-correlated noises and bias force can enhance the collective motion of coupled active Brownian particles (ABPs), i.e., better synchronization between N coupled ABPs. It can provide a possible strategy for controlling active motion. • Cross-correlated noise and bias force can lead to a transition from bimodal to unimodal. • Cross-correlated noises and bias force can enhance the transport and weaken the diffusion of the ABP. • Multiplicative noise can facilitate transport and enhance diffusion of the ABP, whereas the additive noise can weaken the transport of the ABP. • Cross-correlated noises and bias force can enhance the collective motion of coupled ABPs. [ABSTRACT FROM AUTHOR]