1,721,153 research outputs found
Stochastic resonance in complex systems
No full textIn this paper we discuss the mechanism of stochastic resonance in a complex system. We develop a new theory aimed at predicting the renormalization of external forcing due to the 'complexity' of the systems. We also introduce a simple computational method for investigating the dynamics of the system using the spectral properties of the connectivity matrix
A short review on drag reduction by polymers in wall bounded turbulence
No full textIn this paper we review some recent progress in understanding the phenomenon of drag reduction with polymers in wall bounded turbulence
Stochastic resonance: from climate to biology
Full text linkIn this lecture, I will review some basic aspects of the mechanism of stochastic resonance, first introduced as a possible mechanism to explain long term climatic variation. Since then, there have been many applications of stochastic resonance in physical and biological systems. I will show that in complex system, stochastic resonance can substantially change as a function of the "system complexity". Also, I will briefly mention how to apply stochastic resonance for the case of Brownian motors
Characterization of temperature and precipitation fields over Sardinia with Principal Component Analysis and Singular Spectrum Analysis
No full textMultifractal modeling of anomalous scaling laws in rainfall
No full textThe coupling of hydrological distributed models to numerical weather prediction outputs is an important issue for hydrological applications such as forecasting of flood events. Downscaling meteorological predictions to the hydrological scales requires the resolution of two fundamental issues regarding precipitation, namely, (1) understanding the statistical properties and scaling laws of rainfall fields and (2) validation of downscaling models that are able to preserve statistical characteristics observed in real precipitation. In this paper we discuss the first issue by introducing a new multifractal model that appears particularly suitable for random generation of synthetic rainfall. We argue that the results presented in this paper may be also useful for the solution of the second question. Statistical behavior of rainfall in time is investigated through a high-resolution time series recorded in Genova (Italy). The multifractal analysis shows the presence of a temporal threshold, localized around 15-20 hours, which separates two ranges of anomalous scaling laws. Synthetic time series, characterized by very similar scaling laws to the observed one, are generated with the multifractal model. The potential of the model for extreme rainfall event distributions is also discussed. The multifractal analysis of Global Atmospheric Research Program (GARP) Atlantic Tropical Experiment (GATE) radar fields have shown that statistical properties of rainfall in space depend on time durations over which precipitation is accumulated. Further analysis of some rainfall fields produced with a meteorological limited area model exhibited the same anomalous scaling as the GATE fields
Intermittency in turbulence: Multiplicative random process in space and time
No full textWe present a simple stochastic algorithm for generating multiplicative processes with multiscaling both in space and in time. With this algorithm we are able to reproduce a synthetic signal with the same space and time correlation as the one coming from shell models for turbulence and the one coming from a turbulent velocity field in a quasi-Lagrangian reference frame
Homogeneous and Isotropic Turbulence: A Short Survey on Recent Developments
No full textWe present a detailed review of some of the most recent developments on Eulerian and Lagrangian turbulence in homogeneous and isotropic statistics. In particular, we review phenomenological and numerical results concerning the issue of universality with respect to the large scale forcing and the viscous dissipative physics. We discuss the state-of-the-art of numerical versus experimental comparisons and we discuss the dicotomy between phenomenology based on coherent structures or on statistical approaches. A detailed discussion of finite Reynolds effects is also presented
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