... that is close to be a “approximated linear system” in the context of Fourier analysis where the limitation of linearity and superposition principle are used. If the system is nonstationary and nonlinear, the instantaneous or transient spectrum is needed so as to identify system. Hilbert transformation of IMF...

... media heat transfer elasticity temperature distribution Hilbert transforms The influence of heat flow in an elastic medium is an important problem, especially for contact between two elastic bodies. The heat flow may come from a difference in temperature between the contacting solids...