Wavelet­analysis

A comparation of wavelets and empirical modes concepts is performed that represent the most perspective tools to study the structure of nonstationary multimode processes. Their advantages over the classical methods for time series analysis and restrictions of both approaches are discussed that needs to be known for correct interpretation of the obtained results. New possibilities in the study of signals structure at the presence of noise are illuctrated for digital single­channel experimental data of prospecting seismology.

Based on the analysis of experimental data we study the collective dynamics of ensembles from several tens nephrons located on a kidney surface. Using wavelet­analysis, the phenomenon of locking of instantaneous frequencies and phases is studied that is caused by the tubulo­glomerular feedback. It is shown that structural units of the kidney related to distinct nephron trees participate in clusters formation. The entrainment of frequencies and phases of oscillations for large groups of nephrons occurs only for some fragments of experimental data.

Theoretical bases of empirical mode decomposition being one of the new methods of time­frequency analysis of processes with time­varying characteristics are discussed. It is shown that application of this approach together with wavelet­filtering allows one to study in details the structure of multicomponent registered signals recorded in prospecting seismology.