Higher-order spectral analysis of Ueda's circuit

In this paper, the time series integrated from periodically excited Ueda's circuit are studied utilizing bispectral and trispectral techniques. calculations of bicoherence and tricoherence are performed on a route (P1-P3-P9-transient chaos) which the Ueda's circuit follows to chaos. Both bicoherence and tricoherence spectra indicate that for the nonchaotic (limit cycles) motions, the quadratic and cubic nonlinear interactions are strong and both are important to the dynamics? however, the quadratic and cubic nonlinearity becomes weak when the Ueda's circuit is in the chaotic states.