This study was supported by the National Natural Science Foundation of China(Nos.12072203,11872253,12032017);the Hundred Excellent Innovative Talents in Hebei Province(No.SLRC2019037);the“333 talent project”in Hebei Province(No.A202005007);the Natural Science Foundation in Hebei Province of China(Nos.A2019421005,A2019402043,E2019210278);the Hebei Provincial Department of Education Project(Nos.ZD2020328,QN2019149,QN2018237);the Graduate Student Innovation Ability Training Project of Hebei Education Department(CXZZSS2021080).
The periodic-phase-diagram similarity method is proposed to identify the frequency of weak harmonic signals.The key technology is to find a set of optimal coefficients for Duffing system,which leads to the periodic mo...