New technology of sealing unstable cracks and joints of concrete dams

Power Technology and Engineering -     

Water flow rate pulsations with a flicker power spectrum in a commercial sodium steam generator

The spectral characteristics of the water flow rate pulsations in the evaporation module of a steam generator with sodium heating in the BN-600 power-generating unit at nominal power are investigated. The results show that the power spectrum of the flow rate pulsations vary inversely as the frequency (flicker pulsations). The appearance of the high-energy low-frequency pulsations of the water flow rate is attributed to a critical heat transfer regime (nonequilibrium phase transition) which is realized in the evaporation module.__________Translated from Atomnaya Énergiya, Vol. 98, No. 2, pp. 105–110, February, 2005.     

On the problem of rarefied gas flow past blunt axisymmetric bodies

Shock layer separation in flows of rarefied gas past axisymmetric models is determined by interferometric methods. The form of the density jump is established.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 15, No. 5, pp. 843–846, November, 1968.     

1/fNoise under Conditions of Interaction between Phase Transitions

Vibrational modes of combustion under conditions of combustible liquid boiling before the reaction front are investigated experimentally. Fluctuations are observed with the spectral density inversely proportional to frequency (1/fnoise). This phenomenon is associated with the intersection and interaction of nonequilibrium phase transitions. A mathematical model is suggested of the emergence of fluctuations with a 1/fspectrum under conditions of interaction between subcritical and supercritical phase transitions in a distributed system.     

Stability of low-frequency pulsations in a transient heat transfer regime upon phase transitions

Using the principle of maximum entropy, we investigate the stability of stochastic processes with the 1/f power spectrum in the system of two nonlinear stochastic differential equations when modeling pulsations in crisis and transient heat-mass transfer regimes with intensive phase transitions. An analysis of the stability of the resultant process, which appears upon the interaction of the stochastic process and the 1/f spectrum of external deterministic impact, is performed. Under the action of harmonic force, stable resultant processes are divided into two types depending on the amplitude of the harmonic force. We have experimentally studied the influence of harmonic impact on the stability of pulsations with the 1/f spectrum upon the crisis of water boiling on a heated wire. The results are in qualitative agreement with theoretical estimations.     

Limiting resistance of an HMX-based explosive under shock-wave loading

The action of shock-wave loading on specimens of an OTK-90 explosive composition is studied. The limiting levels of loading that correspond to the initial stage of explosive conversion of the specimens impacted by steel plates of different thickness are determined. The limiting resistance of the specimens subjected to the gliding detonation of a TP-83 plastic explosive through a polyurethane-foam layer and also to the gliding and normal detonations of a NIL-1 low-density explosive is examined. It is shown that the boundaries of the transition from the purely mechanical failure of OTK-90 to a mechanochemical reaction that were obtained by different methods of shock-wave loading agree well. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 3, pp. 114–119, May–June 2000.     

Self-organization of critical fluctuations and 1/f spectra under conditions of critical boiling

The results are given of an experimental investigation of the dynamics of vaporization under conditions of changing modes of water boiling on a platinum wire heater and with local Joule heating of aqueous electrolytic solutions. It is found that thermal fluctuations with spectral characteristics inversely proportional to frequency (flicker or 1/f noise) are generated under conditions of film boiling on a vertically oriented heater in a wide range of loads. In the region of loss of stability of film boiling, frequency spectra vary in inverse proportion to the square of the frequency. In experiments in Joule heating of aqueous electrolytes, the flicker noise is observed in the region of changing modes of vapor generation. The experimental results are indicative of the self-organization of the critical behavior of the system in the case of nonequilibrium phase transitions.     

Flicker noise during transition to critical boiling on a nonlinear heater

Experimental results are given of studies into intense heat pulsations with a spectral density inversely proportional to frequency during transition to the local crisis of nitrogen boiling on the surface of current-carrying films of high-temperature superconductors. A theoretical model is suggested of the rise of fluctuations with 1/f spectrum during interaction of intersecting phase transitions in concentrated systems.     

Self-organization of a critical state and 1/f fluctuations caused by the interaction of phase transitions in a distributed system

A mathematical model is proposed that describes the appearance of fluctuations with a spectral density inversely proportional to the frequency as a result of the intersection of phase transitions in a spatially inhomogeneous system. The model is represented by a set of two nonlinear stochastic differential equations with mutually interacting order parameters. It is demonstrated that a random walk in the model potential field corresponding to the intersecting sub-and supercritical phase transitions may lead to the self-organization of a critical state and the appearance of fluctuations with a 1/f spectral density.