Ricerc@Sapienza

In this paper, we consider the problem of disturbance decoupling for a class of non-minimum-phase nonlinear systems. Based on the notion of partially minimum phaseness, we shall characterize all actions of disturbances which can be decoupled via a static state feedback while preserving stability of the internal residual dynamics. The proposed methodology is then extended to the sampled-data framework via multi-rate design to cope with the rising of the so-called sampling zero dynamics intrinsically induced by classical single-rate sampling.

In this paper, we present a Boussinesq type model which is able to simulate wave fields and nearshore currents in coastal regions characterized by morphologically complex coastal lines and irregular seabed and by the presence of coastal structures. The proposed model solves the integral contravariant form of the fully nonlinear Boussinesq equations, from deep water up to just seaward of the surf zones, and the non-linear shallow water equations, in the surf zone, on curvilinear boundary conforming grids.

This paper describes 2-D numerical simulations of velocity and pressure fields generated by non-breaking waves on a vertical breakwater with a recurved parapet wall. The influence of the geometrical characteristics of the parapet is investigated. An impulsive pressure force is identified and discussed with respect to the pure vertical wall case. This force is generated by the seaward flow confinement induced by the surging wave crest. We refer to this impulsive impact as "confined-crest impact".

This paper deals with the analysis of drifter campaigns realized in two different domains, the Gulf of Mexico and the Mar Grande Basin (Italy). Relative dispersion, diffusivity, and velocity variance were estimated, identifying different growth regimes. An exponential growth of the dispersion process was detected during the initial phase of deployment, and empirical laws for horizontal diffusivity were inferred.

Berms deployed at the toe of conventional breakwaters may be needed to reduce bottom settlements and to limit scour in front of the structure due to coastal currents. In the mean time, they may be effective in increasing the stability of the armor layer and also in minimizing the wave overtopping discharge compared to straight sloped conventional breakwaters without a berm. This research aims to provide a new design criterion for the armor layer of conventional breakwaters with submerged berms marked by small thickness compared to water depth.