Disseny d’un comportament en ROS per a mantenir la posició d’un vehicle autònom submarí a partir de referències visuals

En el Centre d'Investigació en Robòtica Submarina (CIRS) de la Universitat de Gironaes disposa de diferents robots submarins els quals utilitzen una arquitectura software anomenada Component Oriented Layered-based Architecture for Autonomy ( COLA2 ), la qual ha estat desenvolupada per estudiants i professors del mateix centre. Per tal de fer aquesta arquitectura més accessible per a professors i estudiant d’altres centres la COLA2 s’està adaptant al Robot Operative System (ROS) que és un framework genèricper al desenvolupament d’aplicacions amb robots. Aquest projecte pretén dissenyar un comportament per al robot Girona500 que estigui desenvolupat dins la versió ROS de l’arquitectura COLA2. El comportament haurà de fer mantenir una determinada posició al robot amb informació visual de la càmera del robot i amb dades de navegació. La tasca de mantenir la posició es de vital importància per a poder realitzar intervencions submarines que requereixen de precisió i, precisament, el medi on es treballa no ajuda

Effects of coastal submarine canyons on tsunami propagation and impact

We analyse the variations produced on tsunami propagation and impact over a straight coastline because of the presence of a submarine canyon incised in the continental margin. For ease of calculation we assume that the shoreline and the shelf edge are parallel and that the incident wave approaches them normally. A total of 512 synthetic scenarios have been computed by combining the bathymetry of a continental margin incised by a parameterised single canyon and the incident tsunami waves. The margin bathymetry, the canyon and the tsunami waves have been generated using mathematical functions (e.g. Gaussian). Canyon parameters analysed are: (i) incision length into the continental shelf, which for a constant shelf width relates directly to the distance from the canyon head to the coast, (ii) canyon width, and (iii) canyon orientation with respect to the shoreline. Tsunami wave parameters considered are period and sign. The COMCOT tsunami model from Cornell University was applied to propagate the waves across the synthetic bathymetric surfaces. Five simulations of tsunami propagation over a non-canyoned margin were also performed for reference. The analysis of the results reveals a strong variation of tsunami arrival times and amplitudes reaching the coastline when a tsunami wave travels over a submarine canyon, with changing maximum height location and alongshore extension. In general, the presence of a submarine canyon lowers the arrival time to the shoreline but prevents wave build-up just over the canyon axis. This leads to a decrease in tsunami amplitude at the coastal stretch located just shoreward of the canyon head, which results in a lower run-up in comparison with a non-canyoned margin. Contrarily, an increased wave build-up occurs on both sides of the canyon head, generating two coastal stretches with an enhanced run-up. These aggravated or reduced tsunami effects are modified with (i) proximity of the canyon tip to the coast, amplifying the wave height, (ii) canyon width, enlarging the areas with lower and higher maximum height wave along the coastline, and (iii) canyon obliquity with respect to the shoreline and shelf edge, increasing wave height shoreward of the leeward flank of the canyon. Moreover, the presence of a submarine canyon near the coast produces a variation of wave energy along the shore, eventually resulting in edge waves shoreward of the canyon head. Edge waves subsequently spread out alongshore reaching significant amplitudes especially when coupling with tsunami secondary waves occurs. Model results have been groundtruthed using the actual bathymetry of Blanes Canyon area in the North Catalan margin. This paper underlines the effects of the presence, morphology and orientation of submarine canyons as a determining factor on tsunami propagation and impact, which could prevail over other effects deriving from coastal configuration.

Estudio de alta resolución de las fallas activas y procesos sedimentarios asociados al Cañón de São Vicente, margen Sudoeste de Iberia

The Southwest Iberian Margin is caracterized by an intense and diffuse seismic activity due to the convergence between Eurasian and African plates...

The Role of Canyons in Strata Formation

This paper provides a spatial and temporal multi-scale approach of European submarine canyons. We fi rst present the long-term geologic view of European margins as related to controls on submarine canyon development. Then we discuss the extent to which submarine canyon systems resemble river systems because both essentially form drainage networks. Finally, we deal with the hortest-term, highestresolution scale to get a fl avor of the current functioning and health of modern submarine canyons in the northwestern Mediterranean Sea. Submarine canyons are unique features of the seafl oor whose existence was known by European fi shermen centuries ago, especially for those canyons that have their heads at short distance from shoreline. Popular names given to specifi c canyons in the different languages spoken in European coastal communities refer to the concepts of a"deep" or"trench." In the old times it was also common thinking that submarine canyons where so deep that nobody could measure their depth or even that they had no bottom. Submarine canyons are just one of the seven different types of seafl oor valleys identifi ed by Shepard (1973) in his pioneering morphogenetic classifi cation. Shepard (1973) defined submarine canyons as"steep-walled, sinuous valleys, with V-shaped cross sections, and relief comparable even to the largest of land canyons; tributaries are found in most of the canyons and rock outcrops abound on their walls." Canyons are features typical of continental slopes with their upper reaches and heads cut into the continental shelf.

Estudio de alta resolución de las fallas activas y procesos sedimentarios asociados al Cañón de São Vicente, margen Sudoeste de Iberia

The Southwest Iberian Margin is caracterized by an intense and diffuse seismic activity due to the convergence between Eurasian and African plates...