Search results for " Statistical"

Predator population depending on lemming cycles

2016

In this paper, a Langevin equation for predator population with multiplicative correlated noise is analyzed. The noise source, which is a nonnegative random pulse noise with regulated periodicity, corresponds to the prey population cycling. The increase of periodicity of noise affects the average predator density at the stationary state.

Stochastic dynamics and mean field approach in a system of three interacting species

2008

The spatio-temporal dynamics of three interacting species, two preys and one predator, in the presence of two different kinds of noise sources is studied. To describe the spatial distributions of the species we use a model based on Lotka-Volterra equations. A correlated dichotomous noise acts on \beta, the interaction parameter between the two preys, and a multiplicative white noise affects directly the dynamics of each one of the three species. We study the time behaviour of the three species in single site for different values of the multiplicative noise intensity, finding noise-induced oscillations of the three species densities with an anticorrelated behaviour of the two preys. Afterwar…

Ac-locking of thermally-induced sine-Gordon breathers

2023

A complete framework for exciting and detecting thermally-induced, stabilized sine-Gordon breathers in ac-driven long Josephson junctions is developed. The formation of long-time stable breathers locked to the ac source occurs for a sufficiently high temperature. The latter emerges as a powerful control parameter, allowing for the remarkably stable localized modes to appear. Nonmonotonic behaviors of both the breather generation probability and the energy spatial correlations versus the thermal noise strength are found. The junction's resistive switching characteristics provides a clear experimental signature of the breather.

Role of the Colored Noise in Spatio-Temporal Behavior of Two Competing Species

2005

We study the spatial distributions of two randomly interacting species, in the presence of an external multiplicative colored noise. The dynamics of the ecosystem is described by a coupled map lattice model. We find a nonmonotonic behavior in the formation of large scale spatial correlations as a function of the multiplicative colored noise intensity. This behavior is shifted towards higher values of the noise intensity for increasing correlation time of the noise.

Multi-State Quantum Dissipative Dynamics in Sub-Ohmic Environment: The Strong Coupling Regime

2015

We study the dissipative quantum dynamics and the asymptotic behavior of a particle in a bistable potential interacting with a sub-Ohmic broadband environment. The reduced dynamics, in the intermediate to strong dissipation regime, is obtained beyond the two-level system approximation by using a real-time path integral approach. We find a crossover dynamic regime with damped intra-well oscillations and incoherent tunneling and a completely incoherent regime at strong damping. Moreover, a nonmonotonic behavior of the left/right well population difference is found as a function of the damping strength.

An intelligent way to predict the building thermal needs: ANNs and optimization

2022

The evaluation of the energy performance of existing or new buildings is a fundamental action to guarantee the feasibility of a project and the achievement of the minimum efficiency requirements. In general, the determination of the thermal loads of a building is carried out via software but their use requires adequate knowledge of physical phenomena and therefore the presence of an expert user. Furthermore, the resolution can be difficult to implement and can require high computational costs; all conditions that can influence the success of a project. Based on these considerations, this work proposes an alternative solution to traditional calculation tools, which in a simple and effective …

MODELLI DATA-DRIVEN VALORIZZAZIONE DELLE INFORMAZIONI DIGITALI A SUPPORTO DEI PROCESSI DECISIONALI DELLA SUPPLY CHAIN

2023

Misure di radioattività ambientale a Palermo: analisi statistica delle concentrazioni in aria di 7Be e 210Pb

2016

In questo lavoro sono presi in considerazione gli andamenti delle concentrazioni in aria di 7Be e, per un più limitato periodo di tempo di 210Pb, e si è proceduto ad una analisi statistica dei dati, prendendo in esame le serie temporali (integrandole per i dati mancanti) dei valori medi mensili e settimanali al fine di operare confronti omogenei con dati disponibili di altre zone geografiche. Sono state studiate le correlazioni fra le serie di dati per i due radionuclidi ed è stata effettuata l’analisi in frequenza al fine di evidenziare ciclicità stagionali. Le analisi effettuate mostrano l’importanza dei processi di trasporto in atmosfera e l’influenza dei parametri meteo-climatici (in pa…

Rateless Codes Performance Analysis in Correlated Channel Model for GEO Free Space Optics Downlinks

2012

A Psychometric Evaluation of the Group Environment Questionnaire in a Sample of Professional Basketball and Soccer Players

2013

Psychometric properties of the Group environment Questionnaire were investigated in a large sample of soccer (n = 222) and professional basketball players (n = 375). Confirmatory factor analysis was performed both on the total sample and on the two sub samples through a multi-group approach; associations between cohesion and the duration of belonging to the team were also explored. Results confirmed the four-factor structure proposed by Carron's original model even though some items with low loadings were eliminated. No signifcant associations were found between team cohesion and the duration of belonging to the team. © Perceptual & Motor Skills 2013.