A circular zone counting method of identifying a Duffing oscillator state transition and determining the critical value in weak signal detection*
Li Meng-Ping, Xu Xue-Mei†, Yang Bing-Chu, Ding Jia-Feng
       
Sample explanations for the circular zone line. (a) f = 0.82, radius of the circular zone is R = 0.8. (b) f = 0.825, radius of the circular zone is R = 0.8. (c) f = 0.83, radius of the circular zone is R = 0.8. (d) f = 0.825, radii of the circular zones from inside to outside are 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1.