Extracting and Stabilizing the Unstable State of Hysteresis Loop

A novel perturbation method for the stabilization of unstable intermediate states of hysteresis loop (i.e. S-shaped curve) is proposed. This method only needs output signals of the system to construct the perturbation form without delay-coordinate embedding technique, it is more practical for real-world systems. Stabilizing and tracking the unstable intermediate branch are demonstrated through the examples of a bistable laser system and delay feedback system. All the numerical results are obtained by simulating each of the real experimential conditions.Comment: 6 pages, REVTEX, 4 ps figure

Ab initio study of shock compressed oxygen

Quantum molecular dynamic simulations are introduced to study the shock compressed oxygen. The principal Hugoniot points derived from the equation of state agree well with the available experimental data. With the increase of pressure, molecular dissociation is observed. Electron spin polarization determines the electronic structure of the system under low pressure, while it is suppressed around 30 $\sim$ 50 GPa. Particularly, nonmetal-metal transition is taken into account, which also occurs at about 30 $\sim$ 50 GPa. In addition, the optical properties of shock compressed oxygen are also discussed.Comment: 5 pages, 5 figure