Articolo in rivista

Rare mutations in evolutionary dynamics

In this paper we study the effect of rare mutations, driven by a marked point process, on the evolutionary behavior of a population. We derive a Kolmogorov equation describing the expected values of the different frequencies and prove some rigorous analytical results about their behavior. Finally,…

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…

Anomaly detection in multichannel data using sparse representation in radwt frames

We introduce a new methodology for anomaly detection (AD) in multichannel fast oscillating signals based on nonparametric penalized regression. Assuming the signals share similar shapes and characteristics, the estimation procedures are based on the use of the Rational-Dilation Wavelet Transform (…

Sub-ms dynamics of the instability onset of electrospinning

Electrospun polymer jets are imaged for the first time at an ultra-high rate of 10 000 frames per second, investigating the process dynamics, and the instability propagation velocity and displacement in space. The polymer concentration, applied voltage bias and needle-collector distance are…

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…

Diffusive limits of 2D well-balanced schemes for kinetic models of neutron transport

Two-dimensional dissipative and isotropic kinetic models, like the ones used in neutron transport theory, are considered. Especially, steady-states are expressed for constant opacity and damping, allowing to derive a scattering S-matrix and corresponding "truly 2D well-balanced" numerical schemes.…

Methane Clathrate Hydrate Nucleation Mechanism by Advanced Molecular Simulations

The nucleation mechanisms of methane hydrates are studied using well-tempered metadynamics and restrained molecular dynamics. The collective variables we used to follow the process are the methane-methane and methane-water coordination numbers, from which we computed the corresponding Landau free…

Flow of a viscoelastic fluid between two rotation circular cylinders subject to suction or injection