1,565 research outputs found

    CFD and aeroelastic analysis of the MEXICO wind turbine

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    This paper presents an aerodynamic and aeroelastic analysis of the MEXICO wind turbine, using the compressible HMB solver of Liverpool. The aeroelasticity of the blade, as well as the effect of a low-Mach scheme were studied for the zero-yaw 15m/s wind case and steady- state computations. The wake developed behind the rotor was also extracted and compared with the experimental data, using the compressible solver and a low-Mach scheme. It was found that the loads were not sensitive to the Mach number effects, although the low-Mach scheme improved the wake predictions. The sensitivity of the results to the blade structural properties was also highlighted

    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

    Monitoring of an aquatic environment in aquaculture using a MEWMA chart

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    Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.[EN] Monitoring an aquatic environment in aquaculture is usually carried out by controlling its physicochemical and biological parameters. The global state of the process is evaluated though the individual conditions shown in each parameter. However, the correlation structure in the data, caused by interdependence between these parameters, provides relevant information which must be controlled. Thus, the complex structure of the data requires a multivariate control method to explore both the individual and interactive effects of the environmental parameters. To achieve this goal, this paper presents a statistical method based on a Multivariate Exponentially Moving Average (MEWMA) chart to monitor the multivariate structure of an aquatic environment in aquaculture, especially in a crop of tilapia in Mozambique. The results show that the adjusted MEWMA chart is more consistent when controlling the conformity and stability of environmental parameters. Therefore, it can be considered an efficient statistical method to monitor an aquatic environment in aquaculture.Mulema, SA.; Carrión García, A. (2019). Monitoring of an aquatic environment in aquaculture using a MEWMA chart. Aquaculture. 504:275-280. https://doi.org/10.1016/j.aquaculture.2019.01.019S27528050

    Steppes, savannahs, forests and phytodiversity reservoirs during the Pleistocene in the Iberian Peninsula

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    A palaeobotanical analysis of the Pleistocene floras and vegetation in the Iberian Peninsula shows the existence of patched landscapes with Pinus woodlands, deciduous and mixed forests, parklands (savannah-like), shrublands, steppes and grasslands. Extinctions of Arctotertiary woody taxa are recorded during the Early and Middle Pleistocene, but glacial refugia facilitated the survival of a number of temperate, Mediterranean and Ibero-North African woody angiosperms. The responses of Iberian vegetation to climatic changes during the Pleistocene have been spatially and temporarily complex, including rapid changes of vegetation in parallel to orbital and suborbital variability, and situations of multi-centennial resilience or accommodation to climatic changes. Regional characteristics emerged as soon as for the Middle Pleistocene, if not earlier: Ericaceae in the Atlantic coast indicating wetter climate, thermo-mediterranean elements in the south as currently, and broad-leaf trees in the northeastern. Overall, steppe landscapes and open Pinus woodlands prevailed over many continental regions during the cold spells of the Late Pleistocene. The maintenance of a high phytodiversity during the glacials was linked to several refuge zones in the coastal shelves of the Mediterranean and intramountainous valleys. Northern Iberia, especially on coastal areas, was also patched with populations of tree species, and this is not only documented by palaeobotanical data (pollen, charcoal) but also postulated by phylogeographical models

    Palinología del paleolítico medio y superior de Cova Beneito (Muro, Alicante)

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    Es presenten els resultats pal.linológics de una secció estratigrafica que correspon al paleolltic superior de la Cova Beneito (Muro, Alacant), la qual completa la seqüencia paleolítica que ara inclou nivells musterians, aurinyacians, solutrians, gravetians i solutreo-gravetians. La secció pol.linífera s'hi tmba escassament a 1-2 m d'una altra estudiada anterionnent, la qual va resultar esteril. Els espectres pol.línics mostren que el paleolltic superior de la zona es va desenvolupar en condicions d’aridesa ambiental prou marcades, la qual cosa està en corrodància amb les dades que s'observen a altres diagrames pol.linics per a l'estadi isotbpic 2 en domini continental. Dins d'un context global, la seqüencia de la Cova Beneito dóna suport a la hipòtesi que durant l'intetpleniglacial wunnià es produrien expansions, no necessàriament, coetànies, de nuclis de vegetació mediterrània, l'amplitud i duració de les quals dependrien de les condicions locals.In this study, the palynology of an Upper Paleolithic stratigraphical section from Cova Beneito (Muro, Alicante) is presented. It completes all the Paleolithic record including Mousterian, Aurignacian, Solutrian, Gravettian and Solutreo Gravenian industries. The polliniferous section is placed 1-2 m apart from a former one which became sterile. According to the pollen spectra, the Upper Paleolithic environment could have been one of severe aridity. This agrees with the conventional palynology in continental domain for the isotopic stage 2. Overall, the Beneito pollen record supports the view that, during the middle last glacial stage, Mediterranean vegetation couM have been widespread, but with the response of vegetation to the climatic change largely depending on local conditions.Se presentan los resultados palinológicos de una sección estratigráfica correspondiente al Paleolítico superior de Cova Beneito (Muro, Alicante), completando así la secuencia paleolítica que ahora incluye niveles musterienses, auriñacienses. solutrenses, gravetienses y solutreo-gravetienses. La sección polinífera se halla apenas a 1-2 m de otra estudiada anteriormente, la cual resultó estéril. Los espectros polínicos muestran que el Paleolítico Superior de la zona se desarrolló en condiciones de aridez ambiental bastante marcadas, lo cual concuerda con los datos que se manejan en otros diagramas polínicos para el estadio isotópico 2 en dominio continental. En un contexto global, la secuencia de Cova Beneito sirve de apoyo a la hipótesis de que durante el interpleniglacial wurmiense se produjeron expansiones, no necesariamente coetáneas, de núcleos de vegetación mediterránea cuya amplitud y duración dependerían de las condiciones locales

    Biomass-modulated fire dynamics during the last glacial-interglacial transition at the central pyrenees (Spain)

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    Understanding long-term fire ecology is essential for current day interpretation of ecosystem fire responses. However palaeoecology of fire is still poorly understood, especially at high-altitude mountain environments, despite the fact that these are fire-sensitive ecosystems and their resilience might be affected by changing fire regimes. We reconstruct wildfire occurrence since the Lateglacial (14.7. cal. ka BP) to the Mid-Holocene (6. cal. ka BP) and investigate the climate-fuel-fire relationships in a sedimentary sequence located at the treeline in the Central Spanish Pyrenees. Pollen, macro- and micro-charcoal were analysed for the identification of fire events (FE) in order to detect vegetation post-fire response and to define biomass-fire interactions. mean fire intervals (mfi) reduced since the Lateglacial, peaking at 9-7.7. cal. ka BP while from 7.7 to 6. cal. ka BP no fire is recorded. We hypothesise that Early Holocene maximum summer insolation, as climate forcing, and mesophyte forest expansion, as a fuel-creating factor, were responsible for accelerating fire occurrence in the Central Pyrenees treeline. We also found that fire had long-lasting negative effects on most of the treeline plant communities and that forest contraction from 7.7. cal. ka BP is likely linked to the ecosystem's threshold response to high fire frequencies.This research has been funded by the projects DINAMO (CGL2009-07992) (funding EGPF — grant ref. BES-2010-038593 and MSC), DINAMO2 (CGL2012-33063), ARAFIRE (2012 GA LC 064), GRACCIE-CONSOLIDER (CSD2007-00067). GGR was funded by the Juan de la Cierva Program (grant ref. JCI2009-04345) and JAE-Doc CSIC Program, LLM was supported by a postdoctoral MINT fellowship funded by the Institute for the Environment (Brunel University), AMC is a Ramón y Cajal fellow (ref: RYC-2008-02431), APS holds a grant funded by the Aragon Government (ref. 17030G/5423/480072/14003) and JAE holds a grant funded by the Basque Country Government (BFI-2010-5)

    Mountain strongholds for woody angiosperms during the Late Pleistocene in SE Iberia

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    Mediterranean mountains played an essential role during glacial periods as vegetation refugia. The SE Iberia Late Pleistocene woody angiosperm fossil and floristic evidences are reviewed in the context of phylogeographical studies aiming to identify (i) spatial patterns related to woody angiosperms glacial survival, (ii) structural and functional characteristics of montane refugia, and (iii) gaps in knowledge on the woody angiosperm patterns of survival in Mediterranean mountains. The distribution of palaeobotanical data for SE Iberia refugia has been found to be taphonomically biased due to the scarcity of available and/or studied high-altitude Late Pleistocene sites. However, Siles Lake data together with floristic inference provide evidences for woody angiosperms’ survival in a high-altitude Mediterranean area. The main features boosting survival at montane contexts are physiographic complexity and water availability. Phylogeography studies have mainly been conducted at a continental scale. Although they cohere with palaeobotanical data to a broad scale, a general lack of sampling of SE Iberian range-edge populations, as well as misconceptions about the origin of the populations sampled, impede to infer the proper location of woody angiosperms’ mountain refugia and their importance in the post-glacial European colonisation. We conclude that floristic, geobotanical, palaeobotanical, ethnographical and genetic evidence should be merged to gain a deeper understanding on the role played by Mediterranean mountains as glacial refugia in order to explain the current distribution of many plants and the large biodiversity levels encountered in Mediterranean mountain areas. This is hallmark for effective and efficient conservation and management

    Linear viscoelastic properties of high reclaimed asphalt content mixes with biobinders

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    The use of high Reclaimed Asphalt (RA) content mixtures together with binders produced from renewable resources (biobinders) is one of the current challenges in pavement engineering research. On one hand, RA has been used for decades but there are still some concerns about its performance, especially when high contents are used (>30%). On the other hand, biobinders are relatively new materials which have to be deeply characterised and studied in order to develop good-practices for their use. In this paper, linear viscoelastic properties of biobinders and bio-mixtures manufactured with high-RA content and biobinders are analysed and discussed. High-modulus mixtures with 50% RA were selected for the mix design. Binders and mixtures were tested over a wide range of asphalt service temperatures and frequencies by means of DSR and two-point bending tests respectively. Results show that biobinders have an important effect on mixtures behaviour. However, no direct links between their linear viscoelastic properties were found. Bio-asphalt mixtures still need further development for commercial exploitation; however the take-away fact of this investigation is that it is possible to manufacture asphalt-like mixtures with acceptable viscoelastic properties while being composed only of RA and non-petroleum based binders

    Cardiovascular risk protection from the Mediterranean diet and olive oil. A transcriptomic update in humans

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    This review highlights the human studies that explore the benefits of the Mediterranean diet and olive oil, based on gene expression analysis. We summarized consistent human transcriptomic studies on cardiovascular risk, based on TMD and olive oil interventions, with real life doses and conditions. A literature review was carried out leading up to February 2016. The results show that the TMD, specially supplemented with virgin olive oil, produces beneficial changes in the transcriptomic response of relevant genes in cardiovascular risk such as CAT, GPX1 and SIRT2. p65 and MCP-1, IL1B, IL6, CXCL1, INF-γ, ARHGAP15 and IL7R, which are involved in inflammation; and ABCA1, SR-B1, PPARBP, PPARα, PPARγ, PPARδ, CD-36 and COX-1, which play an important role in cholesterol efflux. The available data illustrate a transcriptomic effect on atherosclerosis, inflammation and oxidative stress pathways as well as the mentioned genes

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