Experimental observations of cohesive sediment dynamics in aquaculture recirculation tanks

se describe un modelo para velcocidad de caida de agregados validado experimentalmente.Cohesive sediments from non-used food and fish excreta are a main concern in aquaculture recirculation tank design. Excess concentrations of sediments can cause fish death or additional costs of energy for aeration. Flow dynamics in these tanks is represented as a multiphase flow with two disperse phases: one of solids (cohesive sediments) and one of gas (oxygen) because aeration is always needed. This research was carried out to understand the settling behavior of flocs when subjected to a liquid shear rate. A reduced scale model of an aquaculture recirculation tank was built in Plexiglas in order to use Particle Image Velocimetry and Particle Tracking Velocimetry techniques to measure fluid velocities, solid settling velocities, floc shape, and size. The optical techniques provided a description of how the phases organize in space and how this organization is related to the microphysics. Different flow rates and solid concentrations were used to develop varied configurations in the system. Models for floc settling velocity based on fractal theory were calibrated. Cohesive sediments from fish food were observed in long-term experiments at constant fluid shear rate and constant gas flow rates in the recirculation tank. Images were obtained each five minutes. Image analysis provided us with floc settling velocity data and floc size. Using floc settling velocity data, floc density data were obtained for different diameters at equilibrium conditions, after one hour or larger experiments. Statistical analysis of floc velocities for different floc sizes allowed us to obtain an expression for the drag coefficient as a function of floc particle Reynolds number (R*=ρwWsD/μ) where Ws is the floc settling velocity, D is floc diameter, ρw is the liquid mass density and μ is the liquid viscosity. The results are helpful to improve cohesive sediment removal in aquaculture recirculation tanks by providing a tool to obtain optimum sedimentation rates as a function of fluid shear ratesUAE

Methodology to reconstruc virtual cities from the past

Postprint (published version

Tweet my paper: Who handles dissemination on Twitter?

The communication of research results is a task that is not equally distributed among authors. This paper explores how researchers distribute dissemination tasks on Twitter, the main channel for scientific communication. The main goal is to determinate which authorship position is most associated with self-dissemination of papers on Twitter, and whether this pattern is homogeneous across research areas. For Twitter mentions to papers, a large-scale dataset was created by merging Web of Science and Altmetric.com data, while for the identification of scholars on Twitter, an open dataset was used. Our main finding shows that 27% of Twitter users who mention papers are scholars and that only 13% of their mentions were for self-promotion purposes. Likewise, the corresponding author is the main responsible for this dissemination, a role that is mainly carried out by the first author.Full paper available at: https://dapp.orvium.io/deposits/64de4a4995b02025f51d327d/vie

First steps of the FIBRESHIP project: Engineering, production and life cycle management for the complete construction of large length fibre-based ships.

The main objective of the FIBRESHIP project is to enable the building of the complete hull and superstructure of large-length seagoing and inland ships in FRP materials by overcoming few technical challenges. In order to achieve this objective, the project will develop, qualify and audit innovative FRP materials for marine applications, elaborate new design and production guidelines and procedures, generate efficient production and inspection methodologies, and develop new validated software analysis tools. Clear performance indicators will be designed and applied in the evaluation of the different solutions developed for three targeted vessels categories. Finally, the different technologies generated in FIBRESHIP will be first validated and then demonstrated by using advanced simulation techniques and experimental testing on real-scale structures. This paper is dealing with the presentation of the project scope and progress of the FIBRESHIP project over the first six months

Roca WC flapper

Treball desenvolupat dins el marc del programa 'European Project Semester' i l"International Design Project Semester".Toilet flushing is the single highest use of water in the average home. Toilets make up about 31% of overall household water consumption. Most WC bowls used in western countries are fitted with a water trap that uses a large amount of water for preventing odor from the sewers from traveling back into the room. The current market standards differ between 6/3 liters and 4,5/3 liters using this system, and latest developments have proven that the water flush cannot be reduced further. Because of this, finding a way to replace the current water trap with another mechanical solution is the main objective for this project. The basis of this project is to develop a mechanical flapper that would work automatically with the help of springs that would allow for a significant flush water reduction

Nuevos jóvenes, nuevas formas de violencia

El artículo incluye una serie imágenes que hacen referencia a las diferentes formas de violencia juvenil y a continuación, a través de cuadros elaborados por la Dirección General de Justicia Juvenil del Departamento de Justicia de la Generalitat de Catalunya, se exponen una serie de datos desde el 2000-2005 referidos a la criminalidad juvenil.[ES] Una parte significativa de los jóvenes comparten unos rasgos que trascienden más allá de las fronteras geográficas, sociales, religiosas y de género. Disfrutando de altos niveles de libertad personal, al mismo tiempo están sometidos a nuevas formas de control social extremas. Tras un breve repaso a la cuestión de la responsabilidad penal de los menores, se analizan las conductas delictivas de los jóvenes, a través de los diferentes enfoques sobre las concepciones da la criminalidad, para intentar aproximarse a la realidad del problema.[EU] Gazteen parte esanguratsu batek, muga geografiko, sozial, erlijioso eta generoen gainetik haratago dauden bereizgarri batzu konpartitzen ditu. Askatasun pertsonal handia eduki arren, era berean muturreko gizarte kontrol forma berriak pairatzen dituzte. Adingabeen erantzukizun penalaren gainekoa berrikusi eta gero, gazteen delituzko jokabideak aztertzen dira, horretarako kriminalitatearen gaineko ikusmoldeak kontutan izanda, era honetan arazoaren errealitatea hausnartzeko asmoz.[FR] Une partie significative des jeunes partagent des caractéristiques au-delà des frontières géographiques, sociales, religieuses et de genre. En profitant des hauts niveaux de liberté personnelle, en même temps ils sont soumis à de nouvelles formes de contrôle social extrêmes. Après un bref examen à la question de la responsabilité pénale des mineurs, on analyse les conduites délictueuses des jeunes, à travers les différentes approches sur les conceptions de la criminalité, pour essayer de connaître la réalité du problème.[EN] A significant portion of young people share some common characteristics beyond geographic, social, religious and gender frontiers. While enjoying high levels of personal freedom, they are submitted to extreme forms of social control. After a brief review of the criminal responsibility of Minors, youth criminal behaviour is analysed through different approaches to criminality conceptions, trying to come close to the reality of the problem