Browsing Statistical Physics by Author "Pagnini, G."
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Centreofmass like superposition of OrnsteinUhlenbeck processes: A pathway to nonautonomous stochastic differential equations and to fractional diffusion
D’Ovidio, M.; Vitali, S.; Sposini, V.; Sliusarenko, O.; Paradisi, P.; Castellani, G.; Pagnini, G. (20181025)We consider an ensemble of Ornstein–Uhlenbeck processes featuring a population of relaxation times and a population of noise amplitudes that characterize the heterogeneity of the ensemble. We show that the centreofmass ... 
Concurent multiscale physical parametrization of firespotting: A study on the role of macro and mesoscale characteristics of the system
Egorova, V.; Trucchia, A.; Pagnini, G. (2018)The strong impact of wildfires in terms of lives and homes lost and of damage to ecosystems, calls for an urgent improvement in the risk management. The aim of the present research is the improvement of these software ... 
Crossover from anomalous to normal diffusion: truncated powerlaw noise correlations and applications to dynamics in lipid bilayers
MolinaGarcia, D.; Sandev, T.; Safdari, H.; Pagnini, G.; Chechkin, A.V.; Metzler, R. (20181018)The emerging diffusive dynamics in many complex systems shows a characteristic crossover behaviour from anomalous to normal diffusion which is otherwise fitted by two independent powerlaws. A prominent example for a ... 
DarrieusLandau instabilities in the framework of the Gequation
Pagnini, G.; Trucchia, A. (201704)We consider a model formulation of the flame front propagation in turbulent premixed combustion based on stochastic fluctuations imposed to the mean flame position. In particular, the mean flame motion is described by ... 
Discretizations of the spectral fractional Laplacian on general domains with Dirichlet, Neumann, and Robin boundary conditions
Cusimano, N.; Del Teso, F.; GerardoGiorda, L.; Pagnini, G. (20170428)In this work, we propose novel discretisations of the spectral fractional Laplacian on bounded domains based on the integral formulation of the operator via the heatsemigroup formalism. Specifically, we combine suitable ... 
Effective selfsimilar expansion for the GrossPitaevskii equation
Modugno, M.; Pagnini, G.; ValleBasagoiti, M.A. (201804)We consider an effective scaling approach for the free expansion of a onedimensional quantum wave packet, consisting in a selfsimilar evolution to be satisfied on average, i.e., by integrating over the coordinates. A ... 
Finiteenergy Lévytype motion through heterogeneous ensemble of Brownian particles
Sliusarenko, O.; Vitali, S.; Sposini, V.; Paradisi, P.; Chechkin, A.V.; Castellani, G.; Pagnini, G. (20190201)Complex systems are known to display anomalous diffusion, whose signature is a space/time scaling $x \sim t^\delta$ with $\delta \neq 1/2$ in the probability density function (PDF). Anomalous diffusion can emerge jointly ... 
Firespotting generated fires. Part I: The role of atmospheric stability
Egorova, V.; Trucchia, A.; Pagnini, G. (201902)This is the first part of two papers concerning firespotting generated fires. In this part we deal with the impact of macroscale factors, such as the atmospheric stability, and in the second part we deal with mesoscale ... 
Fractional Brownian motion in a finite interval: correlations effect depletion or accretion zones of particles near boundaries
Guggenberger, T.; Pagnini, G.; Vojta, T.; Metzler, R. (201902)Fractional Brownian motion (FBM) is a Gaussian stochastic process with stationary, longtime correlated increments and is frequently used to model anomalous diffusion processes. We study numerically FBM confined to a finite ... 
Fractional Diffusion and Medium Heterogeneity: The Case of the Continuos Time Random Walk
Sposini, V.; Vitali, S.; Paradisi, P.; Pagnini, G. (20210724)In this contribution we show that fractional diffusion emerges from a simple Markovian Gaussian random walk when the medium displays a powerlaw heterogeneity. Within the framework of the continuous time random walk, the ... 
Fractional kinetics emerging from ergodicity breaking in random media
MolinaGarcia, D.; Minh Pham, T.; Paradisi, P.; Manzo, C.; Pagnini, G. (2016)We present a modelling approach for diffusion in a complex medium characterized by a random lengthscale. The resulting stochastic process shows subdiffusion with a behavior in qualitative agreement with single particle ... 
Fractional kinetics in random/complex media
Pagnini, G. (2019)In this chapter, we consider a randomlyscaled Gaussian process and discuss a number of applications to model fractional diffusion. Actually, this approach can be understood as a Gaussian diffusion in a medium characterized ... 
Fractional relaxation with timevarying coefficient
Garra, R.; Giusti, A.; Mainardi, F.; Pagnini, G. (20141231)From the point of view of the general theory of the hyperBessel operators, we consider a particular operator that is suitable to generalize the standard process of relaxation by taking into account both memory effects of ... 
From G  Equation to Michelson  Sivashinsky Equation in Turbulent Premixed Combustion Modelling
Pagnini, G. (20170620)It is well known that the MichelsonSivashinky equation describes hydrodynamic instabilities in turbulent premixed combustion. Here a formulation of the flame front propagation based on the Gequation and on stochastic ... 
Front Curvature Evolution and Hydrodynamics Instabilities
Pagnini, G.; Trucchia, A. (20170607)It is known that hydrodynamic instabilities in turbulent premixed combustion are described by the MichelsonSivashinsky (MS) equation. A model of the flame front propagation based on the Gequation and on stochastic ... 
Front propagation in anomalous diffusive media governed by timefractional diffusion
Mentrelli, A.; Pagnini, G. (20141231)In this paper, a multidimensional model is proposed to study the propagation of random fronts in media in which anomalous diffusion takes place. The front position is obtained as the weighted mean of fronts calculated by ... 
Gaussian processes in complex media: new vistas on anomalous diffusion
Di Tullio, F.; Paradisi, P.; Spigler, R.; Pagnini, G. (201909)Normal or Brownian diffusion is historically identified by the linear growth in time of the variance and by a Gaussian shape of the displacement distribution. Processes departing from the at least one of the above conditions ... 
A generalized Stefan model accounting for system memory and nonlocality
Garra, R.; Falcini, F.; Voller, V.R.; Pagnini, G. (202005)The Stefan problem, involving the tracking of an evolving phasechange front, is the prototypical example of a moving boundary problem. In basic one dimensional problems it is well known that the front advances as the ... 
Langevin equation in complex media and anomalous diffusion
Vitali, S.; Sposini, V.; Sliusarenko, O.; Paradisi, P.; Castellani, G.; Pagnini, G. (20180730)The problem of biological motion is a very intriguing and topical issue. Many efforts are being focused on the development of novel modelling approaches for the description of anomalous diffusion in biological systems, such ... 
The MWright function as a generalization of the Gaussian density for fractional diffusion processes
Pagnini, G. (20131231)The leading role of a special function of the Wrighttype, referred to as MWright or Mainardi function, within a parametric class of selfsimilar stochastic processes with stationary increments, is surveyed. This class ...