La invasió verda

Plantes protagonistes de transtorns ambientals al territori valenci&agrave

Una nova edició de l'Origen destinada al gran públic

Una nova edició de l'Origen destinada al gran públi

Reanalyses for dense shelf water cascading in the Cap de Creus Canyon and the atmospheric winter conditions

Màster de Meteorologia, Facultat de Física, Universitat de Barcelona. Curs: 2022-2023. Tutors: Jesús Peña Izquierdo, Ileana Bladé MendozaIn the Gulf of Lion (GoL), during cold winters, the local northerly winds cool the continental shelf water, increasing its density until it loses enough buoyancy to sink mainly through the submarine canyon of Cap de Creus. This process is known as shelf water cascading. To assess the interannual variability of the intensity of these events in the past decades, we use the reanalysis dataset Med MFC from the Mediterranean Sea, which has proved to correlate well with in-situ observations of cascading. This also provides a 3D view of the water properties and how they evolve in time. Then, we calculate the sea surface heat and buoyancy fluxes that modify the density of the shelf water using the atmospheric ERA5 and hydrological GloFAS reanalyses. The river freshwater input, the heat loss and the precipitation have been proved to influence the density of shelf water and the intensity of cascading. These fluxes are correlated with the modes of climate variability of the Atlantic Ridge (AR) and Scandinavian Blocking (SCAN): positive phases of AR together with negative phases of SCAN in winter create a larger buoyancy loss on the shelf water in the GoL, and vice versa

Modelling of thermal management by hybrid channeling

Friction Stir Welding was born as a technique to join dissimilar metals overcoming the different physical properties. The join is made in a solid state with non-consumable tools, becoming environmentally friendly. The microstructure of the new regions created during FSW shown enhanced properties too interesting for a new technique to appear, Friction Stir Processing. Based on same principles as FSW, FSP performs on metals proceeding to a microstructure refinement and so surface properties. Nevertheless, when the parameters during FSP are improperly settled, some defects emerge in the weld zone. Most outstanding one developed Friction Stir Channeling, a technique which manufactures internal closing channels by a developed tool. One step further, Hybrid Friction Stir Channeling combines, in a simultaneous action, the production of internal channels with the join of different components. This investigation is focused on the study of the parameters involved in the proper performance and functioning of HFSC prototypes for thermal management. The adequate knowledge of these parameters leads to an optimization of HFSC application for heat removal. This dissertation considers three parameters as most relevant ones: channel roughness, thermal bridge by the weld zone and coolant velocity and temperature. Acquired knowledge about the behavior in different configurations determined by these parameters is later applied in the simulation of prototypes proposed for thermal management. Each prototype differs from others in geometry, boundary conditions, heat sources, channel path and application. The influence of each parameter was simulated within different models. Results showed how the increase of the contact area and turbulence in the flow propitiated by roughness aid the heat transfer mechanism significantly improving heat removal. Contact surfaces are not fully contacted due to surface roughness and waviness, where the peaks leave gaps filled by air. Air low thermal conductivity act as a barrier for heat transfer. Weld zone, composed of a continuous material, avoids this resistance and aids the heat to flow through the weld zone. Easiness in heat flow means greater conduction to the coolant and lower maximum temperatures. Coolant velocity has limitations because of pump requirements and frictional losses. The higher the inlet velocity, the higher heat removal. Nonetheless, excessive velocities do not result in excellent efficiencies. There is a point from which the gain in heat removal is too deficient compared with the increase needed in the flow

The Lichen Genus Usnea On Quercus Suber In Iberian Cork-Oak Forests

Fifteen species of Usnea are recorded from Iberian cork-oak forests: U. ceratina, U. comma, U. dasaea, U. esperantiana, U. flammea, U. fulvoreagens, U. glabrata, U. hirta, U. mutabilis, U. rubicunda, U. subcornuta, U. subfloridana U. subscabrosa, U. substerilis and U. wasmuthii. A key for these species is provided. Details of morphology, chemistry, distribution, ecology and taxonomy are discussed. Usnea dasaea is reported as new to the Iberian Peninsula. New chemotypes of U. fulvoreagens (with squamatic acid) and U. wasmuthii (with psoromic acid) have been identified. Distribution maps of U. dasaeaand U. subcornuta in Europe are presented. A new combination, Usnea subfloridana subsp. praetervisa (Asahina) P. Clerc, is propose