Now showing items 1-20 of 36

• #### Centre-of-mass like superposition of Ornstein-Uhlenbeck processes: A pathway to non-autonomous stochastic differential equations and to fractional diffusion ﻿

(2018-10-25)
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 centre-of-mass ...
• #### Concurent multi-scale physical parametrization of fire-spotting: A study on the role of macro- and meso-scale characteristics of the system ﻿

(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 power-law noise correlations and applications to dynamics in lipid bilayers ﻿

(2018-10-18)
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 power-laws. A prominent example for a ...
• #### Darrieus-Landau instabilities in the framework of the G-equation ﻿

(2017-04)
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 ﻿

(2017-04-28)
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 heat-semigroup formalism. Specifically, we combine suitable ...
• #### Effective self-similar expansion for the Gross-Pitaevskii equation ﻿

(2018-04)
We consider an effective scaling approach for the free expansion of a one-dimensional quantum wave packet, consisting in a self-similar evolution to be satisfied on average, i.e., by integrating over the coordinates. A ...
• #### Finite-energy Lévy-type motion through heterogeneous ensemble of Brownian particles ﻿

(2019-02-01)
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 ...
• #### Fire-spotting generated fires. Part I: The role of atmospheric stability ﻿

(2019-02)
This is the first part of two papers concerning fire-spotting 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 ﻿

(2019-02)
Fractional Brownian motion (FBM) is a Gaussian stochastic process with stationary, long-time correlated increments and is frequently used to model anomalous diffusion processes. We study numerically FBM confined to a finite ...
• #### Fractional kinetics emerging from ergodicity breaking in random media ﻿

(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 ﻿

(2019)
In this chapter, we consider a randomly-scaled 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 time-varying coefficient ﻿

(2014-12-31)
From the point of view of the general theory of the hyper-Bessel 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 ﻿

(2017-06-20)
It is well known that the Michelson-Sivashinky equation describes hydrodynamic instabilities in turbulent premixed combustion. Here a formulation of the flame front propagation based on the G-equation and on stochastic ...
• #### Front Curvature Evolution and Hydrodynamics Instabilities ﻿

(2017-06-07)
It is known that hydrodynamic instabilities in turbulent premixed combustion are described by the Michelson-Sivashinsky (MS) equation. A model of the flame front propagation based on the G-equation and on stochastic ...
• #### Front propagation in anomalous diffusive media governed by time-fractional diffusion ﻿

(2014-12-31)
In this paper, a multi-dimensional 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 ﻿

(2019-09)
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 non-locality ﻿

(2020-05)
The Stefan problem, involving the tracking of an evolving phase-change 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 ﻿

(2018-07-30)
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 M-Wright function as a generalization of the Gaussian density for fractional diffusion processes ﻿

(2013-12-31)
The leading role of a special function of the Wright-type, referred to as M-Wright or Mainardi function, within a parametric class of self-similar stochastic processes with stationary increments, is surveyed. This class ...
• #### Modelling and simulation of wildland fire in the framework of the level set method ﻿

(2016-01-01)
Among the modelling approaches that have been proposed for the simulation of wildfire propagation, two have gained considerable attention in recent years: the one based on a reaction-diffusion equation, and the one based ...