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Low-Frequency Fluctuations with 1/f spectra in Critical Regimes with Phase Transitions

Experimental investigation of fluctuation dynamics in critical and transitional modes shows existence of irregular high-energy pulsations with power spectrum inversely proportional to the frequency – so called 1/f spectrum. Such regimes are characterized by the fact that an essential part of the pulsations en-ergy is connected with very slow processes and mean that large high-energy bursts are possible in the sys-tem. Another characteristic feature of such regimes is scale invariance of the fluctuations distribution func-tion. According to the theory, the 1/f fluctuations can emerge in physical systems due to simultaneous phase transitions in presence of sufficiently intensive white noise.
This paper is devoted to description of statisti-cal properties of 1/f fluctuations at non-equilibrium phase transitions in a system of two nonlinear sto-chastic differential equations. It is shown by numeri-cal methods that distributions of duration values of the low-frequency extreme bursts have the power-like form.
Experimental investigation results of statistical characteristics of fluctuation processes at ultrasonic cavitations and explosive boiling of superheated wa-ter jets are presented. Results of the experiments car-ried out fit conclusions of the theoretical model for interacting heterogeneous phase transitions.
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