Antonio Brasiello

A multiscale approach to triglycerides simulations: from atomistic to coarse-grained models and back

The aim of this paper is to provide a simulation strategy to study the liquid-solid transition of triglycerides. The strategy is based on a multiscale approach. A coarse-grained model, parameterized on the basis of reference atomistic simulations, has been used to model the liquid-solid transition. A reverse mapping procedure has been proposed to reconstruct atomistic models from coarse-grained configurations and validated against experimental structural properties. The nucleation and growth of the crystalline order have been analysed in terms of several properties.

Generalized Poisson-Kac Processes: Basic Properties and Implications in Extended Thermodynamics and Transport

Abstract We introduce a new class of stochastic processes in Rn,

Multi-Scale Modelling And Coarse-Grained Analysis Of Triglycerides Dynamics

{{\rm{\mathbb R}}^n},

On the influence of reflective boundary conditions on the statistics of Poisson–Kac diffusion processes

referred to as generalized Poisson–Kac (GPK) processes, that generalizes the Poisson–Kac telegrapher’s random motion in higher dimensions. These stochastic processes possess finite propagation velocity, almost everywhere smooth trajectories, and converge in the Kac limit to Brownian motion. GPK processes are defined by coupling the selection of a bounded velocity vector from a family of N distinct ones with a Markovian dynamics controlling probabilistically this selection. This model can be used as a probabilistic tool for a stochastically consistent formulation of extended thermodynamic theories far from equilibrium.

Ergodicity-breaking bifurcations and tunneling in hyperbolic transport models

In this paper, the effect of a pretreatment on an eggplant drying process is investigated by using a suitable developed mathematical model with shrinkage. The objective is to assess the role of volume variation due to changes in pore structures in the dehydration processes. Parameters assessing eggplant quality are also taken into account and collected both with and without pretreatment. The built model is used to analyze evolutions of dehydration processes carried out at two temperatures to provide evidences of the advantages of using pretreatment to assure high quality of end products.

Markovian nature, completeness, regularity and correlation properties of generalized Poisson-Kac processes

Abstract The paper is focused on Molecular Dynamics (MD) simulations of liquid triglycerides. Triglycerides are the major constituents of edible lipids and therefore represent a key topic in the field of medical science and food engineering. The main drawback of using MD for any practical application is the computational cost needed for long run simulations. Here we present a first effort to overcome this drawback by considering the synergy of two approaches: (a) a coarse-grained modelling of triglycerides molecules which allows the reduction of the equivalent simulation time for more than one order of magnitude with respect to the atomistic simulations; (b) the so-called coarse time-stepper approach (Kevrekidis et al., 2003), which can be used to accelerate the atomistic time evolution computations directly. We show how, using a coarse-grained model, one may reach simulation times of one order of magnitude lower with respect to the atomistic simulations. Moreover, applying the time stepper approach we are able to reduce the simulation time one more order of magnitude, giving an overall gain of two orders of magnitude.

Stochastic foundations of undulatory transport phenomena: generalized Poisson–Kac processes—part III extensions and applications to kinetic theory and transport

We consider the one-dimensional Cattaneo equation for transport of scalar fields such as solute concentration and temperature in mass and heat transport problems, respectively. Although the Cattaneo equation admits a stochastic interpretation–at least in the one-dimensional case–negative concentration values can occur in boundary-value problems on a finite interval. This phenomenon stems from the probabilistic nature of this model: the stochastic interpretation provides constraints on the admissible boundary conditions, as can be deduced from the wave formulation here presented. Moreover, as here shown, energetic inequalities and the dissipative nature of the equation provide an alternative way to derive the same constraints on the boundary conditions derived by enforcing positivity. The analysis reported is also extended to transport problems in the presence of a biasing velocity field. Several general conclusions are drawn from this analysis that could be extended to the higher-dimensional case.

Stochastic foundations of undulatory transport phenomena: generalized Poisson–Kac processes—part II Irreversibility, norms and entropies

We analyze the influence of reflective boundary conditions on the statistics of Poisson–Kac diffusion processes, and specifically how they modify the Poissonian switching-time statistics. After addressing simple cases such as diffusion in a channel, and the switching statistics in the presence of a polarization potential, we thoroughly study Poisson–Kac diffusion in fractal domains. Diffusion in fractal spaces highlights neatly how the modification in the switching-time statistics associated with reflections against a complex and fractal boundary induces new emergent features of Poisson–Kac diffusion leading to a transition from a regular behavior at shorter timescales to emerging anomalous diffusion properties controlled by walk dimensionality of the fractal set.