Sistemas eólicos de energia mais leves que o ar

Os produtores associados às energias eólicas tem nos últimos anos procurado novas formas de produção de energia elétrica mais eficientes e menos dispendiosas que as tecnologias atuais. As soluções atuais apresentam ainda elevados custos de instalação e manutenção para além de terem associadas a si o traço intermitente e irregular do seu recurso natural – o vento. Entre muitas alternativas em estudo, as tecnologias (LTA - Lighter than Air) tem merecido particular interesse devido aos anos de experiência e saber acumulado na área e muito em parte devido ás potencialidades económicas que estas deixam em aberto. A prova chega-nos por mão da Altaeros Energies, start-up fundada no MIT que já tem em fase de testes o seu primeiro protótipo BAT - Buoyant Airborne Turbine (Turbina aerogeradora flutuante). Este artigo ambiciona apresentar esta tecnologia e os seus princípios de funcionamento destas tecnologias, utilizando como exemplo o protótipo da Altaeros que será alvo de um estudo ao nível das suas características aerodinâmicas, bem como ao nível da sua viabilidade económica

Solving motion planning problems

This work considers a family of motion planning problems with movable blocks. Such problem is de ned by a maze grid occupied by immovable blocks (walls) and free squares. There are k movable blocks (stones) and k fixed goal squares. The man is a movable block that can traverse free squares and move stones between them. The problem goal is to move the stones from their initial positions to the goal squares with the minimum number of stone moves. (Párrafo extraído del texto a modo de resumen)Sociedad Argentina de Informática e Investigación Operativa (SADIO

Can Heart Rate Variability Predict the Second Metabolic Threshold in Young Soccer Players?

International Journal of Exercise Science 11(2): 1105-1111, 2018. Heart rate variability (HRV) is an effective method to assess the influence of the autonomic nervous system, which may be directly linked to metabolic demand. The aim of the study was to determine if the second metabolic threshold can be identified by HRV. Thirteen athletes were assessed in cardiopulmonary exercise test with concomitant gas analysis. The RR intervals (RRi) were plotted in a spreadsheet for graphics analysis and the point at which there was a shift in the RRi curve was determined as RRiT2. The second ventilatory threshold (VT2) was used as the gold standard technique. A positive correlation was found in the test time (r = 0.84), heart rate (r = 0.97) and VO2 (r = 0.97) between the VT2 and HRV second threshold (RRiT2). All parameters identified by RRiT2 were lower than predicted by VT2 (p \u3c 0.05)

EN EL VALLE DE SORRAIA (CORUCHE, PORTUGAL): DINÁMICA DEL ASENTAMIENTO DE SOCIEDADES CAMPESINAS ANTIGUAS EN LA MARGEN IZQUIERDA DEL BAJO TAJO (5500 A 1800 A.N.E.)

This article is the result of archaeological and paleoenvironmental investigations carried out within the scope of the ANSOR project in the Sorraia valley (Coruche), on the left bank of the Lower Tagus. In the analysis of settlement dynamics between 5500 and 1800 a.n.e. we considered four moments: 1) The first peasant societies of the ancient Neolithic; 2) The Middle and Late Neolithic; 3) Chalcolithic; 4) The Early Bronze Age. The Sorraia valley was also framed in the framework of the Center and South of Portugal during the period under analysis. Interpretative models are presented for changes in the implantation patterns in the four stages under study, oscillating between paleoenvironmental factors and the socio-economic changes registered in the old peasant societies. Este artículo es el resultado de las investigaciones arqueológicas y paleoambientales realizadas en el ámbito del proyecto ANSOR en el valle de Sorraia (Coruche), en la margen izquierda del Bajo Tajo. En el análisis de la dinámica de asentamiento entre el 5500 y el 1800 a.n.e. consideramos cuatro momentos: 1) Las primeras sociedades campesinas del Neolítico Antiguo; 2) El Neolítico Medio y Reciente; 3) El Calcolítico; 4) La primera Edad del Bronce. El valle de Sorraia se sitúa también en el marco del Centro y Sur de Portugal durante el periodo analizado. Se presentan modelos interpretativos de los cambios en los patrones de implantación en las cuatro etapas estudiadas, dependiendo de los factores paleoambientales y de los cambios socioeconómicos registrados en las antiguas sociedades campesinas. O presente artigo resulta das investigações arqueológicas e paleoambientais realizadas no âmbito do projecto ANSOR no vale do Sorraia (Coruche), margem esquerda do Baixo Tejo. Na análise das dinâmicas de povoamento entre 5500 e 1800 a.n.e. considerámos quatro momentos: 1) As primeiras sociedades camponesas do Neolítico antigo; 2) O Neolítico médio e final; 3) O Calcolítico; 4) A antiga Idade do Bronze. O vale do Sorraia foi igualmente enquadrado no quadro físico do Centro e Sul de Portugal, especialmente entre a Estremadura portuguesa e a margem esquerda do Baixo Tejo, analisando ainda as alterações paleoambientais registadas nesta região durante o período em análise. Apresentam-se modelos interpretativos para as alterações dos padrões de implantação nas quatro etapas em estudo, oscilando-se entre factores paleoambientais e as mudanças socio-económicas registadas nas antigas sociedades camponesas

Enhancement of optical absorption by modulation of the oxygen flow of TiO2 films deposited by reactive sputtering

Oxygen-deficient TiO2 films with enhanced visible and near-infrared optical absorption have been deposited by reactive sputtering using a planar diode radio frequency magnetron configuration. It is observed that the increase in the absorption coefficient is more effective when the O2 gas supply is periodically interrupted rather than by a decrease of the partial O2 gas pressure in the deposition plasma. The optical absorption coefficient at 1.5 eV increases from about 1 102 cm 1 to more than 4 103 cm 1 as a result of the gas flow discontinuity. A red-shift of 0.24 eV in the optical absorption edge is also observed. High resolution transmission electron microscopy with composition analysis shows that the films present a dense columnar morphology, with estimated mean column width of 40 nm. Moreover, the interruptions of the O2 gas flow do not produce detectable variations in the film composition along its growing direction. X-ray diffraction and micro-Raman experiments indicate the presence of the TiO2 anatase, rutile, and brookite phases. The anatase phase is dominant, with a slight increment of the rutile and brookite phases in films deposited under discontinued O2 gas flow. The increase of optical absorption in the visible and near-infrared regions has been attributed to a high density of defects in the TiO2 films, which is consistent with density functional theory calculations that place oxygen-related vacancy states in the upper third of the optical bandgap. The electronic structure calculation results, along with the adopted deposition method and experimental data, have been used to propose a mechanism to explain the formation of the observed oxygen-related defects in TiO2 thin films. The observed increase in sub-bandgap absorption and the modeling of the corresponding changes in the electronic structure are potentially useful concerning the optimization of efficiency of the photocatalytic activity and the magnetic doping of TiO2 films

AN OPTIMIZATION OF A GPU-BASED PARALLEL WIND FIELD MODULE

Atmospheric radionuclide dispersion systems (ARDS) are important tools to predict the impact of radioactive releases from Nuclear Power Plants and guide people evacuation from affected areas. Four modules comprise ARDS: Source Term, Wind Field, Plume Dispersion and Doses Calculations. The slowest is the Wind Field Module that was previously parallelized using the CUDA C language. The statement purpose of this work is to show the speedup gain with the optimization of the already parallel code of the GPU-based Wind Field module, based in WEST model (Extrapolated from Stability and Terrain). Due to the parallelization done in the wind field module, it was observed that some CUDA processors became idle, thus contributing to a reduction in speedup. It was proposed in this work a way of allocating these idle CUDA processors in order to increase the speedup. An acceleration of about 4 times can be seen in the comparative case study between the regular CUDA code and the optimized CUDA code. These results are quite motivating and point out that even after a parallelization of code, a parallel code optimization should be taken into account

HOT WIRE METHOD FOR THE THERMAL CHARACTERIZATION OF MATERIALS: INVERSE PROBLEM APPLICATION

An experimental set-up of the hot wire method is presented. The present design allows the measurement of the temperatures at two different points on the heating wire with an acquisition system that performs measurements at a frequency of 1kHz with a 12 bit numerical converter. An analytical solution for the direct model for the time dependent problem of heat transfer is employed. It is based on the quadrupole method which basically consists in a transfer matrix approach which is possible through the use of Laplace transforms. It extends the electrical analogy of heat transfer problems using the notion of impedance, and allows to take into account the thermal behavior of the wire, as well as contact resistance and heat loss effects in a very simple straightforward way. In the identification process carried on the temperature experimental data relies on a sampling of the data that is logarithmically spaced in time. The initial guesses for the thermal conductivity values are obtained applying the well known and ideal model of the linear temperature evolution versus the logarithm of the time. These values are used to start up the algorithms that are applied in the minimization of the cost functional of the squared residues between measured and calculated temperatures. The precision of the estimates is assessed with the calculated confidence bounds obtained by the variance-covariance matrix at the converged solution

The multidimensionality of female mandrill sociality-A dynamic multiplex network approach

Funding: ASP received funding from the School of Biological Sciences, University of Aberdeen, https://www.abdn.ac.uk/sbs/, and was awarded the Watt Fund via the University of Aberdeen https://www.abdn.ac.uk. These funders do not provide grant numbers. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Data Availability: All relevant data are within the manuscript and its Supporting Information files.Peer reviewedPublisher PD

The dynamics of grooming interactions: maintenance of partner choice and the consequences of demographic variation for female mandrills

A large body of evidence suggests that female Old World monkeys maintain selective long-term grooming interactions with fitness benefits. The last two decades have produced evidence that the regulation of social interactions among primates can be, in part, explained by the Biological Markets theory, with grooming behaviour as the focus of these studies. Grooming facilitates bonding between individuals, constituting an essential part of the regulation of social relationships among female cercopithecids. In contrast to the well-studied baboons (Papio spp), knowledge about the nature of grooming interactions and their regulation is generally lacking for the large, terrestrial species of mandrills (Mandrillus sphinx). We used a combination of social network analysis tools and well-established methods for assessing partner diversity and reciprocity to characterise grooming networks, partner choice and patterns of trade (be groomed, give grooming) among females in a captive group of mandrills, both within and across two separate observation periods. Our results suggest that, even though the relatively stable conditions of captivity allowed the studied females to maintain selective grooming interactions across time, small scale demographic changes affected the grooming dynamics of the group in accordance with the expectations of the Biological Markets theory. In particular, the maturation and consequent integration of a high ranking female into the group’s grooming network from one period to the next resulted in a more pronounced effect of rank on the regulation of grooming interactions. In addition, the influence of the maturation of a dependent infant on the grooming interactions of his mother were evident between periods. Our results also demonstrate that grooming networks are dynamic and that high ranking individuals are not necessarily the most central in grooming networks. Finally, we discuss the potential of social network analysis to identify cases of social exclusion and its consequences for captive management