The Study Of Asymmetric Effects In Stochastic System And The Relevant Issues Of Entropy Transport

In this thesis, asymmetric effects on the statistical properties and stochastic resonance phenomenon of bistable system were studied. Besides, we investigat-ed size effect of different particles diffusing over the entropic barrier. Firstly, the research meaning of asymmetric effect, the research background of stochastic res-onance and entropy transport were comprehensively reviewed. The related theory and research method were introduced in detail. Then, the symmetry restoration and stochastic resonance of the asymmetric bistable system were systematically and deeply. At the same time, we analyzed the size effect of particles based on the transition rate in the process of entropy transport. Main results are as follows:We concretely studied the statistical properties of the asymmetric system driven by correlated noises in the case of delayed system and non-delayed system. The results of calculation indicate that:(1) time delay could induce nonequilibrium phase transition occurring in system, the reentrance phenomenon emergences for that the structure of SPDF peak changes from bimodal to unimodal and becomes bimodal at last;(2) time delay could induce the symmetry restoration of the system; and (3) in the non-delayed system, a correlation between noises could induce the symmetry restoration of the system.The stochastic resonance (SR) phenomena induced by two kinds of noises in asymmetric bistable system were studied:(1) in the system driven by correlated noises, the asymmetric effects on SR phenomenon in the system induced by mul-tiplicative signal depend on initial conditions, i.e., the asymmetry of the system weakens SR for one initial condition and enhances SR for the other initial condi-tion. The asymmetric effects on SR phenomenon in the system induced by the additive signal are independent of initial conditions, i.e., the asymmetry of the system always enhance SR; and (2) in the system driven by bounded noises, both the asymmetry of system and signal frequency weaken SR phenomenon, and there is an optimum value of signal amplitude matching the strongest SR phenomenon.The size effect of Brownian particles diffusing over the entropic barrier in the process of entropy transport was considered. The results of calculation indicate that:(1) the non-Arrhenius behavior of the transition rate based on the entropy-dominated regime in the presence of an interplay of gravitational bias and thermal motion is observed;(2) in the Arrhenius region the escape rate exhibits negative correlation with the particle size under the combined action of variational size and relatively changed boundary.