Acta Physica Sinica (Overseas Edition)

The influence of the gravity and interface kinetics on interface shape and interfacial concentration distribution was numerically investigated by using Galerkin finite element method. A boundary mapping technique was used for dealing with free boundary problem. A two-dimensional steady-state model of TGS crystal growth was developed. The results show that with the increase of the gravity level, the growth rate becomes faster, the growth face becomes more curved and interfacial concentration distribution more non-uniform. The consideration of interface kinetics will cause the decrease of growth rate as compared with the pure transport model. It seems that the interface shape does not change very much within two cases of k = 5.7 cm⁴/(mol·s) and k = ∞, but its position does.

In this paper, with the aid of Lax pairs, a new Bäcklund transformation for the variable coefficient KdV equation is found. Based on the Bäcklund transformation, only if integration is needed, a series of exact solutions can be obtained. This method is important for finding more new and physical-signficant solutions.

Based on a general principle of physics that a physical system is in the most stable state if it is of the lowest energy state, a new method for chaos control is proposed. A calculable generalized energy function in a nonlinear system is suggested for measuring control process. The Henon map and Lorenz system are taken as two typical examples to demonstrate the method. A series of stabilized periodic orbits as well as inverse sequence of chaotic bands are obtained. At the same time, a unified mechanism of physics for several kinds of current chaos control methods is studied using the idea proposed in this paper.

We discuss the optical bistable behavior of a system of N V-type three-level atoms pumped by a coherent input field and coupled to a squeezed vacuum field by treating the optical bistability of such a system as an input-output problem. It is shown that bistability can be realized due to the squeezed vacuum input.

The general dispersion relation for toroidally coupled tearing mode including pressure and other O(²) order corrections is naturally derived based on the structure of ideal magnetohydrodynamic solutions in the outer region. It is found that the inclusion of the O(²) order terms in the diagonal element of E-matrix does not change physical properties of the toroidally coupled tearing mode and only make negligible contribution to the magnitude of growth rate.