Stochastic resonance in coupled weakly-damped bistable oscillators subjected to additive and multiplicative noises

With coupled weakly-damped periodically driven bistable oscillators subjected to additive and multiplicative noises under concern, the objective of this paper is to check to what extent the resonant point predicted by the Gaussian distribution assumption can approximate the simulated one. The investigation based on the dynamical mean-field approx- imation and the direct simulation demonstrates that the pre- dicted resonant point and the simulated one are basically co- incident for the case of pure additive noise, but for the case including multiplicative noise the situation becomes some- what complex. Specifically speaking, when stochastic res- onance （SR） is observed by changing the additive noise in- tensity, the predicted resonant point is lower than the sim- ulated one; nevertheless, when SR is observed by chang- ing the multiplicative noise intensity, the predicted resonant point is higher than the simulated one. Our observations im- ply that the Gaussian distribution assumption can not exactly describe the actual situation, but it is useful to some extent in predicting the low-frequency stochastic resonance of the coupled weakly-damped bistable oscillator.

Confinement-induced modulation of elastic properties of nano-confined fluids in slit pore

Based on statistical mechanics for classical fluids, the general expressions for the elastic moduli of inhomogeneous fluid are derived and expressed as functionals of density functions. Within the framework of classical density functional theory, the bulk modulus of confined argon in slit pore is calculated under different conditions. The effects of vapor pressure, temperature, and pore width on modulus are calculated and investigated. Obvious confinement-induced effect has been observed in the confined argon. In addition, the solvation pressure dependence of the bulk modulus is also investigated,and the results suggest that the Tait–Murnaghan equation is still valid for the confined fluids.

Hydrodynamic Stress Tensor in Inhomogeneous Colloidal Suspensions: an Irving-Kirkwood Extension

Based on statistical mechanics for classical fluids,general expressions for hydrodynamic stress in inhomogeneous colloidal suspension are derived on a molecular level.The result is exactly an extension of the Iving-Kirkwood stress for atom fluids to colloidal suspensions where dynamic correlation emerges.It is found that besides the inter-particle distance,the obtained hydrodynamic stress depends closely on the velocity of the colloidal particles in the suspension,which is responsible for the appearance of the solvent-mediated hydrodynamic force.Compared to Brady’s stresslets for the bulk stress,our results are applicable to inhomogeneous suspension,where the inhomogeneity and anisotropy of the dynamic correlation should be taken into account.In the near-field regime where the packing fraction of colloidal particles is high,our results can reduce to those of Brady.Therefore,our results are applicable to the suspensions with low,moderate,or even high packing fraction of colloidal particles.