According to the design ideology of softswitched extended-period quasi-resonant two-level Boost converter circuit,a soft switching cell of extend-period quasi-resonant had been added to the three-level Boost converter for power factor correction(PFC) applications,then a fully and simple soft-switched extended-period quasi-resonant three-level Boost converter for PFC circuit can be obtained.

For the barotropic potential vorticity equation (named the barotropic model) on a β-plane channel its solution is a stationary, wave-like pattern under a certain thermal forcing, while a quasi-periodic oscillation between two essential flow patterns appears if north-south thermal heating and wave-like topography are added as the .