“…Fourier transforms were studied first, but more modern approaches examine combined time-frequency domain signals. These include wavelet transforms, Empirical Mode Decomposition, short-term Fourier transforms, Hilbert transforms, singular value decomposition, Park's Vector Analysis, and the Wigner-Ville distribution, among others [16,24]. Some faults are easily detected and diagnosed in the frequency domain, but more commonly, the time-frequency band coefficients are passed as features to a classifier algorithm in the usual inferential-sensing approach [16,24].…”