Articolo in rivista

Wavelet simultaneous approximation from samples affected by noise

A system of degenerate parablic nonlinear PDE's: a new free boundary problem

We prove existence of solutions of a new free boundary problem described by a system of degenerate parabolic equations. The problem arises in petroleum engineering and concerns fluid flows in diatomite rocks. The unknown functions represent the pressure of the fluid and a damage parameter of the…

A Bayesian method for multispectral image data classification

The problem of classifying multispectral image data is studied here. We propose a new Bayesian method for this. The method uses "a priori" spatial information modeled by means of a suitable Markov random field. The image data for each class are assumed to be i.i.d. following a multivariate Gaussian…

Effects of Thermal Control and of Passive Solar Elements on the Dynamical Behaviour of a Building

A stable and convergent algorithm to evaluate the Hilbert transform

We deal with the numerical evaluation of the Hilbert transform on the real line by a Gauss type quadrature rule. The convergence and the stability of the method are investigated. The goodness of the numerical results for practical applications is examined.

Efficient Algebraic Multigrid Preconditioners on Clusters of GPUs

Many scientific applications require the solution of large and sparse linear systems of equations using Krylov subspace methods; in this case, the choice of an effective preconditioner may be crucial for the convergence of the Krylov solver. Algebraic MultiGrid (AMG) methods are widely used as…

Flow of a shear thinning fluid between intersecting planes

The non-inertial flow of a shear thinning fluid between intersecting planes is studied using a multi-parameter continuation technique. Unlike the classical linearly viscous fluid, it is found that boundary layers develop even in the case of non-inertial flows in both converging and diverging flow.…

Optimal testing for additivity in multiple nonparametric regression

We consider the problem of testing for additivity in the standard multiple nonparametric regression model. We derive optimal (in the minimax sense) non- adaptive and adaptive hypothesis testing procedures for additivity against the composite nonparametric alternative that the response function…

Jetting to dripping transition: Critical aspect ratio in step emulsifiers

Fully three-dimensional, time-dependent, direct simulations of the non-ideal Navier-Stokes equations for a two-component fluid shed light into the mechanism which inhibits droplet breakup in step emulsifiers below a critical threshold of the width-to-height (w/h) ratio of the microfluidic nozzle.…

Refraction index analysis of light propagation in a colliding gravitational wave spacetime

The optical medium analogy of a given spacetime was developed decades ago and has since then been widely applied to different gravitational contexts. Here we consider the case of a colliding gravitational wave spacetime, generalizing previous results concerning single gravitational pulses. Given…