Articolo in rivista

Numerical Insights in the Solution of Euler Equations of the Variational Image Segmentation

Finding communities in directed networks by PageRank random walk induced network embedding

Community structure has been found to exist ubiquitously in many different kinds of real world complex networks. Most of the previous literature ignores edge directions and applies methods designed for community finding in undirected networks to find communities. Here, we address the problem of…

Dirichlet-to-Neumann mappings and finite-differences for anisotropic diffusion (Reprint from AN INTERNATIONAL JOURNAL COMPUTERS AND FLUIDS)

A general methodology, which consists in deriving two-dimensional finite-difference schemes which involve numerical fluxes based on Dirichlet-to-Neumann maps (or Steklov-Poincare operators), is first recalled. Then, it is applied to several types of diffusion equations, some being weakly…

Particle scattering by a test fluid on a Schwarzschild spacetime: the equation of state matters

The motion of a massive test particle in a Schwarzschild spacetime surrounded by a perfect fluid with equation of state $p_0= w \rho_0$ is investigated. Deviations from geodesic motion are analyzed as a function of the parameter $w$, ranging from $w=1$ which corresponds to the case of massive…

An approximation property of Pisot numbers

Let $q>1$. Initiated by P. Erd\H os et al. in \cite{ErdJooKom1}, several authors studied the numbers $l^m(q)=\inf \{y\ :\ y\in\Lambda_m,\ y\ne 0\}$, $m=1,2,\dots$, where $\Lambda_m$ denotes the set of all finite sums of the form $y=\eps_0 + \eps_1 q + \eps_2 q^2 + \dots + \eps_n q^n$ with…

The "Lost Guardians" of Dante's Inferno: Medium Wave Infrared Imaging Investigations of a XIV Century Illuminated Manuscript

On the occasion of the 700th centenary of the death of Dante Alighieri, medium wave infrared imaging analysis of illuminations of the XIV-century code of the Divina Commedia (MS. 1102), hosted in the Biblioteca Angelica in Rome, was performed and discussed. The investigation was carried out by…

Directional change of tracer trajectories in rotating Rayleigh-Benard convection

The angle of directional change of tracer trajectories in rotating Rayleigh-Benard convection is studied as a function of the time increment tau between two instants of time along the trajectories, both experimentally and with direct numerical simulations. Our aim is to explore the geometrical…

Convection in multiphase fluid flows using lattice Boltzmann methods

We present high-resolution numerical simulations of convection in multiphase flows (boiling) using a novel algorithm based on a lattice Boltzmann method. We first study the thermodynamical and kinematic properties of the algorithm. Then, we perform a series of 3D numerical simulations changing the…

Pointwise convergence of Fourier regularization for smoothing data

The classical smoothing data problem is analyzed in a Sobolev space under the assumption of white noise. A Fourier series method based on regularization endowed with Generalized Cross Validation is considered to approximate the unknown function. This approximation is globally optimal, i.e., the…

A hybrid modified-NSGA-II VNS algorithm for the Multi-Objective Critical Disruption Path Problem

This paper considers a Multiple Objective variant of the Critical Disruption Path problem to extend its suitability in a range of security operations relying on path-based network interdiction, including flight pattern optimisation for surveillance. Given a pair of nodes s and t from the network to…