1,721,089 research outputs found
Stochastic perturbations of the five-components Benard system
No full textThe authors study the effect of small stochastic perturbations on a simple dynamic system describing a Benard flow
Statistical properties of low-frequency variability in the Northern Hemisphere
No full textWe discuss some statistical properties of the observed tropospheric circulation in Northern Hemisphere mid-latitudes. The data used consist of the twice-daily 500 mb height NMC analyses for the period 1966–77. Our analysis is performed in the context of the quasi-unidimensional theory. Estimates of the probability distribution of wave amplitude in the low-frequency range (10–40 days) seem to reveal a bimodal character, while similar estimates for the zonal wind fail to show stable multiple peaks in the occupation frequency, although the process involved seems to be more complex than Gaussian. Possible dynamical interpretations of such statistical properties are discussed in the light of other properties resulting from different types of analysis. The emerging physical picture reveals an intermittent process, operating on planetary scales through a predominantly baroclinic conversion, in agreement with the theoretical considerations of Benzi et al
The mechanism of stochastic resonance
No full textIt is shown that a dynamical system subject to both periodic forcing and random
perturbation may show a resonance (peak in the power spectrum) which is absent when
either the forcing or the perturbation is absent
Random behaviour of nonlinear waves in a closed basin
No full textThis paper concerns the Hamiltonian formulation of non-linear waves in a closed basin. Using the spectral representation of the functional Hamiltonian, we transform our problem in continuous mechanics into a problem in classical mechanics. Truncating the new Hamiltonian at the first order in the slope of the surface elevation and considering only two degrees of freedom, we study the statistical behaviour of this system. We find that under a critical energy the motion in phase space appears to be ordered, whereas above the critical value we have a random behaviour. © 1979 Società Italiana di Fisica
STOCHASTIC RESONANCE IN THE LANDAU-GINZBURG EQUATION
No full textThe mechanism of stochastic resonance is studied in the case of the Landau-Ginzburg equation stochastically and periodically perturbed, by taking advantage of recent developments on the stochastic partial differential equations. Analytical expressions are given for computing the exit times of the system and to estimate the range of the noise for which the stochastic resonance is possible
Heat Transfer in Rayleigh-Bénard Systems
No full textIn this paper we discuss some theoretical aspects concerning the scaling laws of the Nusselt number versus the Rayleigh number in a Rayleigh-Bénard cell. We present a new set of numerical simulations, compare against the predictions of existing models and propose a new theory which relies on the hypothesis of Bolgiano scaling
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