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Stochastic resonance in dynamics and related disciplines
Náprstek, Jiří ; Fischer, Cyril
Stochastic resonance (SR) is a phenomenon which can be observed in some nonlinear dynamic systems under combined excitation including deterministic harmonic force and random noise. This phenomenon was observed the first in the early 1940s when investigating the Brownian motion. Later several disciplines in optics, plasma physics, biomedicine and social sciences encountered effects of this type. However, the actual discovery and start of intensive period of investigation is dated in early 1980s when the idea of SR initiated remarkable inter disciplinary interest including most areas of physics, chemistry and neuro-physiology with a significant overlap to engineering and industrial area. Promising opportunities to employ SR in mechanics emerged only recently to model certain post-critical effects in non-linear dynamics and simultaneously to develop new vibration damping devices, energy harvesting facilities, sophisticated measuring technics and others. The aim of the paper is to present information about a new challenging discipline offering a large field of basic research and possibilities for practical applications.
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Aeroelastic divergence modeled by means of the stochastic resonance
Náprstek, Jiří ; Pospíšil, Stanislav
The divergence is one of the most important and dangerous phenomenon of aeroelastic post-critical states occurring at a prismatic slender beam in a cross-flow. This phenomenon manifests by stable periodic hopping between two nearly constant limits perturbed by random noises. Experimental observation and numerical simulation motivates an idea to model this process as the effect of the stochastic resonance. Being observed and practically used in a number of disciplines in physics (optics, plasma physics, atd.) its mathematical basis follows in the most simple case from properties of the Duffing equation with negative linear part of the stiffness. The occurrence of this phenomenon depends on certain combinations of input parameters, which can be determined theoretically and verified experimentally in the wind tunnel.
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Stochastic resonance of cylinder induced wind flow
Pospíšil, Stanislav ; Kuznetsov, Sergeii ; Trush, Arsenii ; Král, Radomil
The response of a dynamic nonlinear single degree of freedom system to combination of addtive random Gaussian white noise and external deterministic periodic force applied to the aerodynamic phenomena is studied. It is coming to light that under certain circumstances the jumping between wells of the bistable elastic potential can occur leading to internal hopping. The frequency of this hopping can be for certain combination of input parameters nearly the constant and corresponding to external periodic force frequency. This state leads to high ratio of periodic component amplitude and intensity of the random component of the response proces. As the object was chosen in tubulent flow.
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Stochastic resonance in a simple duffing equation
Náprstek, Jiří
The response of a dynamic nonlinear single degree of freedom system with cubic characteristic to a combination of additive random Gaussian white noise and external deterministic periodic force is studied. It is coming to light that under certain circumstances the jumping between wells of the bistable elastic potential can occur leading to interwell hopping. The frequency of this hopping can be for certain combination of input parameters nearly constant and corresponding to external periodic force frequency. This state leads to high ratio of periodic component amplitude and intensity of the random component of the response process. In such a case the system can be used as a harmonic selective resonator detecting the useful weak harmonic signal in the high noisy background.
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