785 research outputs found

    CFD investigation of a complete floating offshore wind turbine

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    This chapter presents numerical computations for floating offshore wind turbines for a machine of 10-MW rated power. The rotors were computed using the Helicopter Multi-Block flow solver of the University of Glasgow that solves the Navier-Stokes equations in integral form using the arbitrary Lagrangian-Eulerian formulation for time-dependent domains with moving boundaries. Hydrodynamic loads on the support platform were computed using the Smoothed Particle Hydrodynamics method. This method is mesh-free, and represents the fluid by a set of discrete particles. The motion of the floating offshore wind turbine is computed using a Multi-Body Dynamic Model of rigid bodies and frictionless joints. Mooring cables are modelled as a set of springs and dampers. All solvers were validated separately before coupling, and the loosely coupled algorithm used is described in detail alongside the obtained results

    Synthesis and Functionalization of Monodisperse Near-ultraviolet and Visible Excitable Multifunctional Eu3+, Bi3+:REVO4 Nanophosphors for Bioimaging and Biosensing Applications

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    Near-ultraviolet and visible excitable Eu- and Bi-doped NPs based on rare earth vanadates (REVO4, RE = Y, Gd) have been synthesized by a facile route from appropriate RE precursors, europium and bismuth nitrate, and sodium orthovanadate, by homogeneous precipitation in an ethylene glycol/water mixture at 120 °C. The NPs can be functionalized either by a one-pot synthesis with polyacrylic acid (PAA) or by a Layer-by-Layer approach with poly(allylamine hydrochloride) (PAH) and PAA. In the first case, the particle size can also be tuned by adjusting the amount of PAA. The Eu- Bi-doped REVO4 based nanophosphors show the typical red luminescence of Eu(III), which can be excited through an energy transfer process from the vanadate anions, resulting in a much higher luminescence intensity in comparison to the direct excitation of the europium cations. The incorporation of Bi into the REVO4 structure shifts the original absorption band of the vanadate anions towards longer wavelengths, giving rise to nanophosphors with an excitation maximum at 342 nm, which can also be excited in the visible range. The suitability of such nanophosphors for bioimaging and biosensing applications, as well as their colloidal stability in different buffer media of biological interest, their cytotoxicity, their degradability at low pH, and their uptake by HeLa cells have been evaluated. Their suitability for bioimaging and biosensing applications is also demonstrated.European Union 267226Ministerio de Economía y Competitividad MAT2014-54852-

    Influence of air velocity and temperature on ultrasonically assisted low temperature drying of eggplant

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    [EN] The aim of this work was to evaluate the feasibility of power ultrasound (US) application during the low temperature drying (LTD) of eggplant, analyzing the influence of the process variables linked to the air flow (velocity and temperature) on the drying kinetics and different quality aspects of the dehydrated product. For that purpose, eggplant (Solanum melongena var. Black Enorma) cubes (8.6 mm side) were dried at different air velocities (1, 2, 4 and 6 m/s) and temperatures (10, 0 and −10 ◦C) without (AIR) and with (AIR + US) US application. The rise in the air velocity and temperature led to an increase in the drying rate in AIR experiments. US application accelerated the drying process under every experimental condition tested, shortening the drying time by up to 87%. As for the quality parameters, no remarkable influence of the process variables (US application, air velocity and temperature) on the rehydration, reconstitution in olive oil or hardness of the rehydrated product was observed.The authors acknowledge the financial support of the Spanish Ministerio de Economia y Competitividad (MINECO) and the European Regional Development Fund (ERDF) through project DPI2012-37466-CO3-03 and the FPI fellowship (BES-2010-033460) granted to J.V. Santacatalina and the Generalitat Valenciana through the project PROMETE0II/2014/005.Santacatalina, JV.; Soriano, J.; Cárcel Carrión, JA.; García Pérez, JV. (2016). Influence of air velocity and temperature on ultrasonically assisted low temperature drying of eggplant. Food and Bioproducts Processing. 100:282-291. https://doi.org/10.1016/j.fbp.2016.07.010S28229110

    NON-PETROLEUM-BASED BINDERS FOR PAVING APPLICATIONS: RHEOLOGICAL AND CHEMICAL INVESTIGATION ON AGEING EFFECTS

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    The massive exploitation of non-renewable natural resources which has taken place in the last decade has led to significant global environmental concerns. In such a context, the use of non-petroleum-based binders for the construction of bound layers of flexible pavements can represent an effective solution to limit crude oil depletion. The research work presented in this paper focused on the effects of ageing on the rheological and chemical characteristics of a non-bituminous binder, indicated in the study as a “biobinder”, and a traditional neat bitumen selected as a reference material. Binders were analyzed in four ageing conditions obtained by making use of the Rolling Thin Film Oven and of the Pressure Ageing Vessel. Rheological behaviour of binders was investigated by means of oscillatory tests carried out in a wide range of temperatures and frequencies with a dynamic shear rheometer. Chemical structure was explored via Thin Layer Chromatographic analyses and Fourier Transform Infrared Spectroscopy. The experimental work demonstrated that mechanisms of ageing which are involved in biobinders completely differ from those experienced by petroleum-based binders. Concerns were expressed with respect to the applicability to non-conventional binders of currently available ageing techniques and of chemical characterization methods

    Measurement of radon-induced backgrounds in the NEXT double beta decay experiment

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    The measurement of the internal 222^{222}Rn activity in the NEXT-White detector during the so-called Run-II period with 136^{136}Xe-depleted xenon is discussed in detail, together with its implications for double beta decay searches in NEXT. The activity is measured through the alpha production rate induced in the fiducial volume by 222^{222}Rn and its alpha-emitting progeny. The specific activity is measured to be (38.1±2.2 (stat.)±5.9 (syst.))(38.1\pm 2.2~\mathrm{(stat.)}\pm 5.9~\mathrm{(syst.)})~mBq/m3^3. Radon-induced electrons have also been characterized from the decay of the 214^{214}Bi daughter ions plating out on the cathode of the time projection chamber. From our studies, we conclude that radon-induced backgrounds are sufficiently low to enable a successful NEXT-100 physics program, as the projected rate contribution should not exceed 0.1~counts/yr in the neutrinoless double beta decay sample.Comment: 28 pages, 10 figures, 6 tables. Version accepted for publication in JHE

    Au-delà du radiocarbone : analyse de taxons et contexte combinés pour la détection de problèmes taphonomiques. Un exemple dans les Grottes de Santa Maira (Alicante, Espagne)

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    Les datations par le radiocarbone permettent de dater une séquence, un niveau ou du matériel isolé, mais leur résultat numérique doit être confronté aux données archéostratigraphiques, bioarchéologiques et à la culture matérielle du contexte daté. Dans ce travail, nous allons présenter l’étude d’une intrusion de restes bioarchéologiques du Mésolithique dans un niveau solutréen sur le site des grottes de Santa Maira. Nous avons effectué l’analyse taphonomique en comparant la distribution spatiale et l’âge radiocarbone des restes anthracologiques et anthropologiques, identifiés au préalable au niveau taxonomique. Ce protocole a permis de délimiter aussi bien la zone affectée par l’intrusion que sa nature et son origine possible. Dans ce cas, l’identification du matériel daté a été primordiale pour son interprétation ultérieure, car l’identification des marqueurs typiques du Solutréen (Pinus tp. nigra), et l’association de certaines espèces (Quercus et Homo), ont été déterminantes pour en détecter le caractère intrusif dans le contexte du Solutréen.Radiocarbon dating makes it possible to date a sequence, level or isolated material, but the numerical result obtained must be compared with the archaeostratigraphic and bioarchaeological data and the material culture from the dated context. In this paper we present the study of an intrusion of Mesolithic bioarchaeological remains in a Solutrean level at the Santa Maira caves site. The taphonomic analysis has been carried out by comparing the spatial distribution and radiocarbon age of the anthracological and anthropological remains previously identified at a taxonomic level. This protocol has made it possible to define both the nature and possible origin of the intrusion and the area affected by it. In this case, the identification of the dated material has been crucial to its subsequent interpretation, as the identification of typical markers of the Solutrean (Pinus tp. nigra) and the association of certain species (Quercus and Homo) have been the key to detect the intrusive nature of the latter in a Solutrean context
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