Articolo in rivista

Energy Dissipation measures in Three-Dimensional Porous Media

Reflection of internal gravity waves in the form of quasi-axisymmetric beams

Preservation of the angle of reflection when an internal gravity wave hits a sloping boundary generates a focusing mechanism if the angle between the direction of propagation of the incident wave and the horizontal is close to the slope inclination (near-critical reflection). This paper provides an…

Intermittency in the velocity distribution of heavy particles in turbulence

The statistics of velocity differences between pairs of heavy inertial point particles suspended in an incompressible turbulent flow is studied and found to be extremely intermittent. The problem is particularly relevant to the estimation of the efficiency of collisions among heavy particles in…

Generation of Persistent Scatterers in Non-Urban Areas: The Role of Microwave Scattering Parameters

In this work, we study the capability of the ground surface to generate Persistent Scatterers (PS) based on the lithology, slope and aspect angles. These properties affect the scattering behavior of the Synthetic Aperture Radar (SAR) signal, the interferometric phase stability and, as a consequence…

Convergence of numerical schemes for viscosity solutions to integro-differential degenerate parabolic problems arising in financial theory

We study the numerical approximation of viscosity solutions for Parabolic Integro-Differential Equations (PIDE). Similar models arise in option pricing, to generalize the Black-Scholes equation, when the processes which generate the underlying stock returns may contain both a continuous part and…

A numerical method for a class of non-linear integro-differential equations on the half line

Twisted gravitational waves of Petrov type D

Twisted gravitational waves (TGWs) are nonplanar unidirectional Ricci-flat solutions of general relativity. Thus far only TGWs of Petrov type II are implicitly known that depend on a solution of a partial differential equation and have wave fronts with negative Gaussian curvature. A special Petrov…

Fractal Encoding

Spacetime Splitting, Admissible Coordinates and Causality

To confront relativity theory with observation, it is necessary to split spacetime into its temporal and spatial components. The timelike threading approach involves fundamental observers that are at rest in space; indeed, this (1+3) splitting implies restrictions on the gravitational potentials $(…

Sondaggio su Archimede: la parola ai lettori (e non)

Risultati di un sondaggio sulla rivista Archimede