Analysis of Renewable Energy Policies Related to Repowering the Wind Energy Sector: the Spanish Case

In countries that started early with wind energy, the old wind turbines were located in places where the wind is often very good. Since the best places in which the wind is concerned are occupied by old wind turbines (with lower capacity than the more recent ones) the trend is to start replacing old turbines with new ones. With repowering, the first generation of wind turbines can be replaced by modern multi-megawatt wind turbines. The aim of this article is to analyze energy policies in the Spanish energy sector in the repowering of wind farms from the viewpoint of the current situation of the wind energy sector. The approach presented in this article is meant to explain what have been the policies related to the repowering sector making a brief analysis of the spectrum of different stimulii that are demanded by the market analyzing also the future perspectives of the repowering sector by establishing the new opportunities based on the new published regulations

Methanol dehydration on carbon-based acid catalysts

Methanol dehydration to produce dimethyl ether (DME) is an interesting process for the chemical industry since DME is an important intermediate and a promising clean alternative fuel for diesel engines. Pure or modified γ-aluminas (γ-Al2O3) and zeolites are often used as catalysts for this reaction. However, these materials usually yield non desirable hydrocarbons and undergo fast deactivation. In this work, we study the catalytic conversion of methanol over an acid carbon catalyst obtained by chemical activation of olive stone with H3PO4. A significant amount of phosphorus remains over the catalyst surface after the activation process, mostly in form of C-O-PO3 and C-PO3 groups, which provide the carbon a relatively high surface acidity and oxidation resistance. Methanol decomposition on this catalyst yields selectivities to DME higher than 82% at 623K and methanol conversion of 34%, under the operating conditions studied. The activated carbon catalytic activity and stability, under inert and oxidant atmospheres, as well as different regeneration procedures, were studied. In the absence of oxygen, the catalyst suffers a progressive deactivation by coke deposition on the active acid sites (Fig. 1). The presence of oxygen modifies the carbon surface chemistry, probably through oxygen spillover on the catalyst surface, where the availability of labile oxygen avoids catalyst deactivation. A reaction mechanism has been proposed where methanol dehydration seems to proceed through an Eley-Rideal mechanism, which assumes the adsorption of water and oxygen spillover on the acid active sites, avoiding coke deposition

Optimal Resource Allocation in Relay-Assisted Cellular Networks With Partial CSI

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Rendimientos de la mano de obra por horas-hombre en el área de construcción de viviendas para la empresa constructora MAVACON

Proyecto de Graduación (Licenciatura en Ingeniería en Construcción) Instituto Tecnológico de Costa Rica. Escuela de Ingeniería en Construcción, 2007.The following project measures labor work performance in house building for MAVACON Construction Company. The main objective is to obtain the performance of labor work per worker in an hour time, to apply as a tool in planning and budget for this kind of projects. MAVACON currently does not count with this sort of information and is currently working with monetary capacity per activity ratios, which has very small advantages and efficiency. As a first approach, a measure instrument was selected in the behavioral studies so that, later on, it would be possible to obtain variable measurements that are of interest in this study. Next, data was codified to proceed in comparing with other sources of information and data given by the company. Data for performance of labor work obtained in this project is reliable to apply as a base for calculation of budget in upcoming projects.Instituto Tecnológico de Costa Rica. Escuela Ingeniería en Construcción; Empresa constructora Mavacon

Dark Matter Halo Properties vs. Local Density and Cosmic Web Location

We study the effects of the local environmental density and the cosmic web environment (filaments, walls, and voids) on key properties of dark matter halos using the Bolshoi-Planck LCDM cosmological simulation. The z = 0 simulation is analysed into filaments, walls, and voids using the SpineWeb method and also the VIDE package of tools, both of which use the watershed transform. The key halo properties that we study are the specific mass accretion rate, spin parameter, concentration, prolateness, scale factor of the last major merger, and scale factor when the halo had half of its z = 0 mass. For all these properties, we find that there is no discernible difference between the halo properties in filaments, walls, or voids when compared at the same environmental density. As a result, we conclude that environmental density is the core attribute that affects these properties. This conclusion is in line with recent findings that properties of galaxies in redshift surveys are independent of their cosmic web environment at the same environmental density at z ~ 0. We also find that the local web environment of the Milky Way and the Andromeda galaxies near the centre of a cosmic wall does not appear to have any effect on the properties of these galaxies' dark matter halos except for their orientation, although we find that it is rather rare to have such massive halos near the centre of a relatively small cosmic wall.Comment: 23 page

Poly[(R)-3-hydroxybutyrate] production under different salinity conditions by a novel Bacillus megaterium strain

Bacillus megaterium uyuni S29, isolated from the Bolivian salt lake Uyuni, displays a high capability to produce poly[(R)-hydroxybutyrate] (PHB) in industrial culture media. In order to analyze the influence of salt on biomass formation and PHB production, cultivations at different NaCl concentrations were carried out according to the salinity conditions of the habitats of the strain’s original isolation. In this preliminary report, the strain showed considerable adaptability to media of different salinity, obtaining the best results for both cellular growth and PHB production in media containing 45 g/L NaCl. The strain grew at 100 g/L NaCl and PHB production was observed even at high salt levels of 250 g/L without unwanted concurrent spore formation. Its tolerance to high salt concentrations together with auspicious PHB productivity makes this strain appealing not only for PHB production, but also for other biotechnological applications such as the treatment of salty wastewater; additional studies will be needed to further increase PHB productivity.Postprint (published version

Nivel de ansiedad estado-rasgo en estudiantes de una universidad privada en Lima Metropolitana en 2023

El objetivo de este estudio fue conocer el nivel de ansiedad estado rasgo de estudiantes de una universidad privada en lima metropolitana en 2023. En términos generales este trabajo tiene un diseño de investigación cuantitativa no experimental transversal. La población estuvo constituida por 272 estudiantes de último año de la carrera, teniendo una muestra de 131 estudiantes. El instrumento usado en esta investigacion fue el Inventario de ansiedad estado rasgo (IDARE), el cual fue utilizado para resolver la pregunta de investigación ¿Cuál es el nivel de ansiedad estado-rasgo en estudiantes de una universidad privada en Lima Metropolitana en 2023? Los resultados obtenidos son los siguientes: El nivel de ansiedad estado es alto 100 (76.34%), ansiedad estado medio 27 (20.61%), ansiedad estado bajo 4 (3.05%) y el nivel de ansiedad rasgo es alto 88 (67.17%), ansiedad rasgo medio 35 (26.72%), ansiedad rasgo bajo 8 (6.11%). Esto quiere decir que el último año de la carrera genera en ellos un cierto nivel de ansiedad estado alto por las diversas actividades que deben realizar, mientras que la ansiedad rasgo es menor, es decir, si bien algunos presentan en su personalidad como rasgo en ellos debido a eventos pasados, la mayoría es causada por acontecimientos estresantes recientes.The objective of this study was to determine the level of state-trait anxiety of students from a private university in metropolitan Lima in 2023. In general terms, this work has a cross-sectional, non-experimental, quantitative research design. The population consisted of 272 students in the last year of the career, having a sample of 131 students. The instrument used in this research was the State-Trait Anxiety Inventory (IDARE), which was used to solve the research question: What is the level of state-trait anxiety in students of a private university in Metropolitan Lima in 2023? The results obtained are the following: The level of state anxiety is high 100 (76.34%), medium state anxiety 27 (20.61%), low state anxiety 4 (3.05%) and the level of trait anxiety is high 88 (67.17%). , medium trait anxiety 35 (26.72%), low trait anxiety 8 (6.11%). This means that the last year of the degree generates in them a certain level of high state anxiety due to the various activities they must carry out, while trait anxiety is lower, that is, although some present in their personality as a trait in them. due to past events, most are caused by recent stressful events

A probabilistic fatigue crack growth life approach to the definition of inspection intervals for railway axles

Different options that rely on fracture mechanics are currently used in engineering during the design and assessment of components. One of the most important aspects is the time taken for a crack to extend to its critical size. If this time is long enough, a design concept based on inspection intervals can be applied, as is it the case of a railway axle component. To define inspection intervals that ensure the continuous and safe operation of a damage-tolerant railway axle, a reliable estimation of its fatigue crack growth life is required. Due to the uncertainties involved in the fatigue process, inspections must be devised not only considering the uncertainties in the performance of the inspection technique, but also based on a probabilistic lifespan prediction. From this premise, this paper presents a procedure for determination of inspection intervals that uses a conservative fatigue crack growth life estimation based on the lifespan probability distribution. A practical example to illustrate the reliability-based inspection planning methodology in a railway axle under random bending loading is given. The inspection intervals are further assessed in terms of overall probability of detecting cracks in successive inspections and in terms of probability of failure, considering the probability of detection curve of the non-destructive testing technique. The procedure developed provides recommendation for the definition of inspection intervals and associated inspection techniques