Large Eddy Simulations of Wind Turbines

Over the past years the demand of energy from renewable sources has been increasing due to increased environmental awareness and foreseeable shortage of non-renewable energies. This has had a strong impact on wind energy powerplants. In fact in order to supply large quantities of energy high-density clusters of wind turbines have been designed. However, the actual production has been lower than the expected because of wake interactions, which are more severe as more densely the turbines are placed, and turbulent motion. It follows that in order to optimize the power extraction from wind a deep understanding of wakes features and dynamics is required. Historically employed engineering models do not provide such a detailed knowledge and their predictions on wakes characteristics may be quite erroneous due the simplifying assumptions they rely upon. Conversely Large-Eddy Simulations (LES) take into account the dynamics of wind turbine flows without making a priori hypotheses on airflow behaviour. Therfore LES results are expected to be more detailed and accurate. In the present thesis, LES of wind turbine flows have been performed. The results obtained have been discussed and compared to the predictions of the simplified engineering models. The impact of the subgrid-scale (SGS) model, which is a key feature of LES, has also been investigated within the framework of eddy-viscosity subgrid-scale models

ANDEAN CONDOR (VULTUR GRYPHUS) NESTING IN NORTHEASTERN COLOMBIA AND DIFFERENCES IN LAYING DATES ALONG THE ANDES

ABSTRACT Little is known about the breeding behavior of the Andean Condor in the wild, especially in the Northern Andes, where densities of this species are low and their nests are difficult to find. We describe an active Andean Condor nest found in March 2015 on the western slope of the eastern Colombian Andes, representing the first country nest record since 1972, and report observations on nesting behavior. We recorded behavior of the male and female attending the nest using direct observations and a camera trap during two months. Both parents attended the nest, but the female did so significantly longer than the male. We assume that the nesting attempt failed because our photographic observation showed no evidence of the adults, the egg, or any chick at the end of the observation period. In addition, we collated available information about the nesting and incubation periods of Andean Condors in the wild along the Andes range. We found latitudinal differences in laying dates. Egg laying occurs in the second half of the year in southern latitudes of the Andean Condor’s range (Chile, Argentina), and primarily in the first half of the year in northern latitudes (Colombia, Ecuador, Peru). RESUMEN ∙ Nidificación del Cóndor Andino (Vultur gryphus) en el norte de la cordillera oriental de Colombia y diferencias en las temporadas de incubación en los AndesEl comportamiento reproductivo del Cóndor Andino es poco conocido, especialmente en el norte de los Andes, en donde las poblaciones de la especie se encuentran reducidas en número y sus nidos son difíciles de encontrar. En éste artículo presentamos el hallazgo de un nido activo de Cóndor Andino en el páramo del Almorzadero, en la Cordillera Oriental colombiana en marzo de 2015. Este sería el primer registro de un nido de cóndores silvestres para Colombia desde 1972. Se presentan adicionalmente descripciones del comportamiento de los adultos en cuanto al cuidado del nido y atención del huevo realizadas mediante observaciones con binoculares y fotografías capturadas con una cámara trampa durante un periodo de dos meses. Mediante los dos métodos de registro (observación directa y fotografías de la cámara trampa), se encontró que, aunque los dos padres atendieron el nido y el huevo, la hembra lo hizo durante un tiempo significativamente mayor. Se consideró que el evento de reproducción fue fallido dado que no se obtuvieron registros de los adultos, el huevo o el polluelo al final de la temporada de observación. Debido a que las variaciones climáticas generadas por la latitud afectan la fisiología y biología reproductiva de las aves, se realizó una revisión de los artículos disponibles sobre las temporadas de anidación de la especie a lo largo de la Cordillera de los Andes. La información disponible sugiere que la latitud puede tener un efecto sobre las temporadas de incubación del Cóndor Andino, ocurriendo en el sur de los Andes (Chile, Argentina) en el segundo semestre del año y para la región norte (Colombia, Ecuador, Perú) durante el primer semestre

ANALISA POSTUR KERJA DENGAN NORDIC BODY MAP & REBA PADA TEKNISI PAINTING DI PT. JAKARTA TEKNOLOGI UTAMA MOTOR PEKANBARU

PT. Jakarta Teknologi Utama Motor Pekanbaru adalah perusahaan perbaikan body kendaraan. Dalam pelaksanaan pekerjaannya terdapat keluhan yang dirasakan teknisi khususnya bagian painting, yaitu keluhan rasa sakit pada punggung dan bagian tubuh lain yang disebabkan oleh kesalahan postur kerja atau ketidak ergonomisan fasilitas kerja yang dapat mempengaruhi kondisi kesehatan, produktivitas serta kualitas hasil kerja. Berdasarkan penilaian dengan metode REBA (Rapid Entire Body Assesment) menunjukkan bahwa aktivitas pengecatan (a) termasuk kategori high risk artinya perlu perbaikan segera. Aktivitas pengamplasan (b) termasuk kategori very high risk artinya perlu perbaikan sekarang. Sedangkan aktivitas pendempulan (c) termasuk dalam kategori medium risk yang berarti diperlukan perbaikan pada postur ini. Rekomendasi yang diberikan agar dapat mengurangi resiko cedera pada teknisi yaitu perlu ada perbaikan posisi kerja dan penambahan peralatan kerja

Evaluación de la composición y abundancia de residuos en las faenas de pesca de arrastre en el golfo de Valencia (Mediterráneo Español)

La investigación sobre residuos sólidos, principalmente plásticos, presentes en los fondos de pesca de arrastr del Golfo de Valencia (España), tuvo como objetivo general conocer su composición y abundancia. Se muestreó durante 21 días (1043 km recorridos en 160 horas de arrastre), en el transcurso de los ocho meses que duró el trabajo de campo. Tales áreas fueron designadas por el Patrón de Pesca de las faenas. La clasificación fue manual y, atendiendo a su composición, se incluyeron en seis categorías: plásticos, metales, vidrios, maderas, textiles y otros. Los envases de plástico, además de ser contados como unidades, fueron pesados con el resto de plásticos. Se obtuvieron 697 artículos diferentes, de los cuales: 33,4% fueron plásticos, 26.3% metales, 17% vidrios, 12.3% maderas, 9.4% textiles, 1.6% otros y 77.5 kg plásticos.ABSTRACTThe general purpose of the research on solid wastes, mainly plastics, existing in the trawling seabed of the Gulf of Valencia, is to find their composition and abundance. For 21 days during the eight months of field work, 1043 km were sampled during the 160 hours of trawling. The areas sampled were designated by the preexisting trawling pattern. The classification was done manually and according to its composition six fundamental kinds of residues were established: plastics, metals, glasses, woods, textiles and others. Plastic containers were counted as units and weighted with the rest of the plastics. 697 different items were obtained: 33.4% plastics, 26,3% metals, 17% glasses, 12,3% woods, 9.4% textiles, 1.6% others and a total of 77.5 kg of plastics.La investigación sobre residuos sólidos, principalmente plásticos, presentes en los fondos de pesca de arrastr del Golfo de Valencia (España), tuvo como objetivo general conocer su composición y abundancia. Se muestreó durante 21 días (1043 km recorridos en 160 horas de arrastre), en el transcurso de los ocho meses que duró el trabajo de campo. Tales áreas fueron designadas por el Patrón de Pesca de las faenas. La clasificación fue manual y, atendiendo a su composición, se incluyeron en seis categorías: plásticos, metales, vidrios, maderas, textiles y otros. Los envases de plástico, además de ser contados como unidades, fueron pesados con el resto de plásticos. Se obtuvieron 697 artículos diferentes, de los cuales: 33,4% fueron plásticos, 26.3% metales, 17% vidrios, 12.3% maderas, 9.4% textiles, 1.6% otros y 77.5 kg plásticos.ABSTRACTThe general purpose of the research on solid wastes, mainly plastics, existing in the trawling seabed of the Gulf of Valencia, is to find their composition and abundance. For 21 days during the eight months of field work, 1043 km were sampled during the 160 hours of trawling. The areas sampled were designated by the preexisting trawling pattern. The classification was done manually and according to its composition six fundamental kinds of residues were established: plastics, metals, glasses, woods, textiles and others. Plastic containers were counted as units and weighted with the rest of the plastics. 697 different items were obtained: 33.4% plastics, 26,3% metals, 17% glasses, 12,3% woods, 9.4% textiles, 1.6% others and a total of 77.5 kg of plastics

The visible environment of galaxies with counterrotation

In this paper we present a statistical study of the environments of 49 galaxies in which there is gas- or stellar- counterrotation. The number of possible companions in the field (to apparent magnitude 22), their size and concentration were considered. All the statistical parameters were analysed by means of Kolgomorov-Smirnov tests, using a control sample of 43 galaxies without counterrotation. From our data, no significant differences between the counter-rotating and control samples appear. This is different to Seyfert or radio-loud galaxies which lie in environments with a higher density of companions. On the contrary, if a weak tendency exists, for galaxies with gas counterrotation only, it is discovered in regions of space where the large scale density of galaxies is smaller. Our results tend to disprove the hypothesis that counterrotation and polar rings derive from a recent interaction with a small satellite or a galaxy of similar size. To a first approximation, they seem to follow the idea that all galaxies are born through a merger process of smaller objects occurring very early in their life, or that they derive from a continuous, non-traumatic infall of gas that formed stars later. Whatever the special machinery is which produces counterrotation or polar rings instead of a co-planar, co-rotating distribution of gas and stars, it seems not to be connected to the present galaxy density of their environments.Comment: 9 pages, 1 figure, accepted for publication in A&

The Orthogonal Gaseous Kinematical Decoupling in the Sa Spiral NGC 2855

We present major and minor-axis kinematics of stars and ionized gas as well as narrow and broad-band surface photometry of the Sa spiral NGC 2855. In the nuclear regions of this unbarred and apparently undisturbed spiral galaxy the gas is rotating perpendicularly to the galaxy disk. We suggest that this kinematically-decoupled component is the signature of an acquisition process in the history of this galaxy.Comment: 7 pages, 4 PostScript figures. Accepted for pubblication in A&A. Figs. 1 and 3 at lower resolution. Data tables will be available at CD

Ionized gas and stellar kinematics of seventeen nearby spiral galaxies

Ionized gas and stellar kinematics have been measured along the major axes of seventeen nearby spiral galaxies of intermediate to late morphological type. We discuss the properties of each sample galaxy distinguishing between those characterized by regular or peculiar kinematics. In most of the observed galaxies ionized gas rotates more rapidly than stars and have a lower velocity dispersion, as is to be expected if the gas is confined in the disc and supported by rotation while the stars are mostly supported by dynamical pressure. In a few objects, gas and stars show almost the same rotational velocity and low velocity dispersion, suggesting that their motion is dominated by rotation. Incorporating the spiral galaxies studied by Bertola et al. (1996), Corsini et al. (1999, 2003) and Vega Beltran et al. (2001) we have compiled a sample of 50 S0/a-Scd galaxies, for which the major-axis kinematics of the ionized gas and stars have been obtained with the same spatial (~1'') and spectral (~50km/s) resolution, and measured with the same analysis techniques. This allowed us to address the frequency of counterrotation in spiral galaxies. It turns out that less than 12% and less than 8% (at the 95% confidence level) of the sample galaxies host a counterrotating gaseous and stellar disc, respectively. The comparison with S0 galaxies suggests that the retrograde acquisition of small amounts of external gas gives rise to counterrotating gaseous discs only in gas-poor S0s, while in gas-rich spirals the newly acquired gas is swept away by the pre-existing gas. Counterrotating gaseous and stellar discs in spirals are formed only from the retrograde acquisition of large amounts of gas exceeding that of pre-existing gas, and subsequent star formation, respectively.Comment: 14 pages, 33 figures, A&A accepte

Influenza Vaccination in Italian Healthcare Workers (2018-2019 Season): Strengths and Weaknesses. Results of a Cohort Study in Two Large Italian Hospitals

Background: Annual vaccination is the most effective way to combat influenza. As influenza viruses evolve, seasonal vaccines are updated annually. Within the European project Development of Robust and Innovative Vaccine Effectiveness (DRIVE), a cohort study involving Italian healthcare workers (HCWs) was carried out during the 2018-2019 season. Two aims were defined: to measure influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza cases and to conduct an awareness-raising campaign to increase vaccination coverage. Methods: Each subject enrolled was followed up from enrollment to the end of the study. Each HCW who developed ILI was swabbed for laboratory confirmation of influenza. Influenza viruses were identified by molecular assays. A Cox regression analysis, crude and adjusted for confounding variables, was performed to estimate the IVE. Results: Among the 4483 HCWs enrolled, vaccination coverage was 32.5%, and 308 ILI cases were collected: 23.4% were positive for influenza (54.2% A(H1N1) pdm09; 45.8% A(H3N2)). No influenza B viruses were detected. No overall IVE was observed. Analyzing the subtypes of influenza A viruses, the IVE was estimated as 45% (95% CI: -59 to 81) for A(H1N1) pdm09. Conclusions: Vaccination coverage among HCWs increased. Study difficulties and the circulation of drifted variants of A(H3N2) could partly explain the observed IVE

Structural and Luminescence Properties of Fe 3+ Doped Antimony Lead Borophosphate Glass

ABSTRACT Structural and luminescence properties of borophosphate glasses with different modifier doped with transition metal ions have been investigated in this stud

Tailoring residual stress profile of Selective Laser Melted parts byLaser Shock Peening

The paper describes a new approach in controlling and tailoring residual stress profile of parts made by Selective Laser Melting (SLM). SLM parts are well known for the high tensile stresses in the as – built state in the surface or subsurface region. These stresses have a detrimental effect on the mechanical properties and especially on the fatigue life. Laser Shock Peening (LSP) as a surface treatment method was applied on SLM parts and residual stress measurements with the hole – drilling method were performed. Two different grades of stainless steel were used: a martensitic 15-5 precipitation hardenable PH1 and an austenitic 316L. Different LSP parameters were used, varying laser energy, shot overlap, laser spot size and treatments with and without an ablative medium. For both materials the as-built (AB) residual stress state was changed to a more beneficial compressive state. The value and the depth of the compressive stress was analyzed and showed a clear dependence on the LSP processing parameters. Application of LSP on SLM parts showed promising results, and a novel method that would combine these two processes is proposed. The use of LSP during the building phase of SLM as a “3D LSP” method would possibly give the advantage of further increasing the depth and volume of compressive residual stresses, and selectively treating key areas of the part, thereby further increasing fatigue life