Data comparison between three acoustic doppler current profilers deployed in OBSEA platform in North-Western Mediterranean

Three different Acoustic Doppler Current Profilers (ADCP) have been deployed in OBSEA platform, a 20 meters depth underwater observatory cabled with a 4 km mixt cable to Vilanova i la Geltru’s coast. Two months of continuous data have been collected in order to confirm their proper operation and long term North current characteristic from the area.Peer Reviewe

Development of the second subsea node of obsea expandable observatory

Peer Reviewe

Data comparison between three acoustic doppler current profilers deployed in OBSEA platform in north-western Mediterranean

Three different Acoustic Doppler Current Profilers (ADCP) have been deployed in OBSEA platform, a 20 meters depth underwater observatory cabled with a 4 km mixt cable to Vilanova i la Geltru’s coast. Two months of continuous data have been collected in order to confirm their proper operation and long term North current characteristic from the areaPeer ReviewedPostprint (published version

Actualización de la electrónica de control de la boya oceanográfica del observatorio OBSEA

Peer Reviewe

Upgrade of the obsea expandable seafloor observatory

Peer Reviewe

Automatic panoramic image creation system from OBSEA PTZ underwater camera

This article is a description about how to take advantage of an underwater PTZ camera to obtain an immersive panoramic image of the seabed environment.Peer Reviewe

Underwater light estimation using the OBSEA camera

This is a description of the method used in the OBSEA observatory to obtain a value for the amount of light present in the seafoor using the existing video surveillance camera.Peer Reviewe

Synthesis and study of new piezoelectric (Bi0.5Na0.5)TiO3-BaTiO3 based materials

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2017, Tutor: Elena Cerdeiras MonteroPiezoelectric materials based on lead zirconate titanate (PZT) are widely used in a large number of electronic devices due to their excellent properties. This improvement occurs in a region of the phase diagram related to a morphotropic phase boundary (MPB). However, the major drawback is the environmental and health problems arising from the presence of lead due to its high toxicity. Therefore, nowadays and during last years, the scientific community has focused on the search for lead-free piezoelectric materials. (Bi0.5Na0.5)TiO3-BaTiO3 based ceramics (BNT-BT) has attracted considerable interest attributable to their similar characteristics to PZT. This system has a morphotropic phase boundary where a great piezoelectric response is obtained and, for this reason, BNT-BT system is considered a promising candidate to replace lead-based piezoelectric materials. However, even with the large number of studies carried out there is no exact composition around MPB where the best properties are obtained. So, it is necessary to continue doing research and try to improve the functional properties. Hence, the goal of this work has been the study of different aspects associated with (Bi0.5Na0.5)TiO3-BaTiO3 system based ceramic materials.In this work, the preparation of BNT-BT based ceramics has been made by solid state reaction and their characterization has been carried out with the different techniques used on solid state chemistry. The planetary ball mill has been stablished as an important part of the synthesis pathway and optimizing the sintering conditions has been done. High density ceramics have been obtained in all compositions with a relative density around 98%. In all cases, perovskite unique phase ceramics have been obtained with coexistence of rhombohedric and tetragonal phase, confirming that they are on the morphotropic phase boundary. Using Scanning Electron Microscopy, the presence of a BNT matrix with grains of BT on the obtained ceramics has been observed. In order to improve the functional properties of these materials, the effect of lanthanide donor dopants has been studied, focusing on the influence of different radius and their concentration. Through X-Ray Diffraction the introduction of dopants on the BNT-BT structure has been confirmed since the diffraction maximums have been shifted to higher angles, meaning the incorporation of lower radius cations and the creation of cationic vacancies. The introduction of Lanthanum has provoked a morphologic variation of the barium titanate grains, which leads us to believe that Lanthanum has been introduced on the BaTiO3 structure, as it was expected due to the stoichiometry of the compound. The dielectric properties of BNT-BT based ceramics have been studied on the morphotropic phase transition, obtaining high values of relative permittivity for the non-doped ceramic and low dielectric losses in all compositions. The Praseodymium doped BNT-BT shows a dielectric behavior dependent on frequency at room temperature, both related to relative permittivity and dielectric losses, better than the non-doped BNT-BT

Cabling, connectors and splices structure for the OBSEA. Expandable subsea observatory

The OBSEA observatory, for its construction, characteristics and location in the seafloor, needs a cabling and connections structure capable to satisfy its finality and to resist the adverse conditions of the sea environment.Peer ReviewedPostprint (published version

Power Supply control of the obsea seafloor

The aim of this paper is to present the design and construction process of the power supply needed for a remote data acquisition system. It is based on twelve AC to DC switching converters in a serial connection and a logic programmable controller (PLC). The energy is transmitted to the acquisition system, which is located several kilometers away, by means of a cable. The supply system has been designed with a higher capacity than the current requirements of the subsea station and the controller decides constantly the best configuration required at each moment.Peer ReviewedPostprint (published version