Seasonal ARIMA Models for Wind Speed Time Series

Wind Speed Forecasting by Box-Jenkins Models

The possibility of modelling observed wind speed time series and forecasting their future values is presented in this paper. Seasonal autoregressive integrated moving average (SARIMA) models are applied to time series formed by four years hourly average wind speed measurements in thirty sites of Sicily. Our approach is considerably different from the original one (the Box-Jenkins approach) since it is completely automatic. We use a peculiar feature of wind speed on a land area, its daily period, to identify a class of SARIMA models within which to find the best fitting model by information criteria (here we employ AICC). Here we report the results, concerning the fit and forecast accuracy, …

Wind Speed Forecasting

This paper aims at providing a general class of stochastic models for hourly average wind speed time series taking into account all the main features of wind speed data, namely autocorrelation, non-Gaussian distribution, seasonal and diurnal nonstationarity. It will be shown that the methodology developed in this study, tested using the data recorded in two sites of Italy, attains valuable results in terms both of modelling and forecasting.

Stochastic models for wind speed time series: a case study

Signature of Quantum Interferences in Above Threshold Detachment of Negative Ions by a Short Infrared Pulse

The effect of an intense external linearly polarized radiation field on the angular distributions and polarization states of the photons emitted during the radiative capture of a free electron by a bare nucleus into the ground state of the bound system is investigated. On symmetry grounds it is predicted that emission of elliptically polarized photons occurs when the momentum of the electron beam is not aligned to the direction of the oscillating field. The predictions are corroborated by numerical calculations of recombination rates carried out within a modified Keldysh-type treatment, in order to account for Coulomb effects. It is found that strong modifications to the angular distributio…

IMAGE PROCESSING IN POLLUTION VULNERABILITY ASSESSMENT OF SICILY AQUIFERS

It is generally acknowledged that vulnerability mapping represents an essential tool for territory management. Intrinsic vulnerability can be generally described as “the susceptibility of the aquifer systems, in their different components and in different geometric and hydrodynamics situations, to swallow and diffuse, also mitigating the effects, a fluid or water-transported pollutant, in such a way to produce impact on the groundwater quality, in space and time”. Assessment procedures of vulnerability consider a number of parameters, the estimation of which is usually difficult and very often insufficient to correctly represent aquifer’s features. As aquifers are closely influenced by nume…

Wind speed stochastic models: a case study for the mediterranean area

Experimental and Modeling Analyses of Human Motion Across the Static Magnetic Field of an MRI Scanner

It is established that human movements in the vicinity of a permanent static magnetic field, such as those in magnetic resonance imaging (MRI) scanners induce electric fields in the human body; this raises potential severe risks of health to radiographers and cleaners exposed routinely to these fields in MRI rooms. The relevant directives and parameters, however, are based on theoretical models, and accurate studies on the simulation of the effects based on human movement data obtained in real conditions are still lacking. Two radiographers and one cleaner, familiar with MRI room activities and these directives, were gait analyzed during the execution of routine job motor tasks at different…

statistical modeling of wind velocity: individual and collective perspective