Ajustes de funções de distribuição de probabilidade à radiação solar global no Estado do Rio Grande do Sul

O objetivo deste trabalho foi verificar o ajuste das séries de dados de radiação solar global média decendial, de 22 municípios do Estado do Rio Grande do Sul, às funções de distribuições de probabilidade normal, log-normal, gama, gumbel e weibull. Aplicou-se o teste de aderência de Kolmogorov-Smirnov, nas 792 séries de dados (22 municípios x 36 decêndios) de radiação solar global média decendial, para verificar o ajuste dos dados às distribuições normal, log-normal, gama, gumbel e weibull, totalizando 3.960 testes. Os dados decendiais de radiação solar global média se ajustam às funções de distribuições de probabilidade normal, log-normal, gama, gumbel e weibull, e apresentam melhor ajuste à função de distribuição de probabilidade normal.

Development and evaluation of neural network models to estimate daily solar radiation at Córdoba, Argentina

The objective of this work was to develop neural network models of backpropagation type to estimate solar radiation based on extraterrestrial radiation data, daily temperature range, precipitation, cloudiness and relative sunshine duration. Data from Córdoba, Argentina, were used for development and validation. The behaviour and adjustment between values observed and estimates obtained by neural networks for different combinations of input were assessed. These estimations showed root mean square error between 3.15 and 3.88 MJ m-2 d-1 . The latter corresponds to the model that calculates radiation using only precipitation and daily temperature range. In all models, results show good adjustment to seasonal solar radiation. These results allow inferring the adequate performance and pertinence of this methodology to estimate complex phenomena, such as solar radiation.

Coeficientes médios da equação de Angström-Prescott, radiação solar e evapotranspiração de referência em Brasília

O objetivo deste trabalho foi estimar os coeficientes médios a e b da equação de Angström-Prescott, em Brasília, e seus efeitos sobre o cálculo da radiação solar global (Rs) e da evapotranspiração de referência (ETo). Foram utilizados dados da estação meteorológica da Embrapa Hortaliças, do período de 1978 a 2003. Os coeficientes médios foram determinados por análise de regressão linear, no período todo e em períodos mensais e anuais. Utilizando-se o coeficiente calculado e os propostos pela FAO (0,25 e 0,50) estimaram-se Rs e ETo, e avaliaram-se os seus desempenhos. Os coeficientes médios mensais a variaram de 0,241 a 0,345, e b de 0,430 a 0,515. Os coeficientes médios anuais a e b foram 0,278 e 0,498, e os do período geral foram 0,282 e 0,490, respectivamente. A performance entre esses coeficientes na estimativa da radiação não diferiu. No mês de julho, foram verificados as piores estimativas e os piores desempenhos. Com as estimativas de Rs e os coeficientes médios calculados, as estimativas de ETo não diferiram dos observados, tendo-se constatado um ótimo desempenho, independentemente do coeficiente utilizado. Dependendo do tipo de aplicação final dos dados, recomenda-se utilizar, por sua simplicidade, os coeficientes médios obtidos para o período geral.

L'ocupació altimperial del solar del mercat de Santa Caterina. Un possible centre productor ceràmic

En aquest article es presenta la fase de la intervenció realitzada al mercat de Santa Caterina que es desenvolupa en l’època altimperial romana i està relacionada amb els inicis de la ciutat de Barcino. En funció de les estructures recuperades i la gran quantitat de material d’escòries ceràmiques recollides, les restes documentades s’han identificat amb una zona de producció ceràmica suburbial, on podrien produir-se tant ceràmiques comunes com recipients amfòrics. Aquests últims són els que han aportat més informació, tant per la quantitat com per la diversitat de marques recollides, que han permès ampliar el coneixement sobre les possibles produccions a la ciutat i els circuits del vi a la zona.

Uso da radiação solar pelo milho sob diferentes preparos do solo, espaçamento e disponibilidade hídrica

O objetivo deste trabalho foi avaliar a eficiência de interceptação e de uso da radiação fotossinteticamente ativa (RFA) pela cultura do milho em diferentes sistemas de manejo do solo, arranjos de plantas e disponibilidade hídrica. O milho foi cultivado em plantio direto e preparo convencional, na combinação com duas disponibilidades hídricas (irrigado e sequeiro) e espaçamentos de 40 e 80 cm entre fileiras de plantas. Em cada tratamento, foram instalados sensores para medida da RFA transmitida pela cultura, na superfície do solo, ao passo que a RFA incidente foi medida acima da cultura. A redução da distância entre fileiras aumentou a eficiência de interceptação em todos os tratamentos. Sob plantio direto, a cultura apresentou maior eficiência de interceptação em relação ao preparo convencional. O deficit hídrico diminuiu a eficiência de interceptação devido ao enrolamento foliar, e esse efeito foi mais pronunciado em preparo convencional, em ambos espaçamentos estudados. Embora a eficiência de interceptação tenha sido maior no espaçamento de 40 cm, a eficiência de uso não diferiu entre espaçamentos, mas diminuiu em condições de deficit hídrico.

Solar radiation use efficiency by soybean under field conditions in the Amazon region

The objective of this work was to evaluate the efficiency of soybean (Glycine max) in intercepting and using solar radiation under natural field conditions, in the Amazon region, Brazil. The meteorological data and the values of soybean growth and leaf area were obtained from an agrometeorological experiment carried out in Paragominas, Pará state, during 2007 and 2008. The radiation use efficiency (RUE) was obtained from the ratio between the above-ground biomass production and the intercepted photosynthetically active radiation (PAR) accumulated to 99 and 95 days after sowing, in 2007 and 2008, respectively. Climatic conditions during the experiment were very distinct, with reduction in rainfall in 2007, which began during the soybean mid-cycle, due to the El Niño phenomenon. An important reduction in the leaf area index and biomass production was observed during 2007. Under natural field conditions in the Amazon region, the values of RUE were 1.46 and 1.99 g MJ-1 PAR in the 2007 and 2008 experiments, respectively. The probable reason for the differences found between these years might be associated to the water restriction in 2007 coupled with the higher air temperature and vapor pressure deficit, and also to the increase in the fraction of diffuse radiation that reached the land surface in 2008.

Forecasting the Earth"s radiation belts and modeling solar energetic particle events: Recent results from SPACECAST

High-energy charged particles in the van Allen radiation belts and in solar energetic particle events can damage satellites on orbit leading to malfunctions and loss of satellite service. Here we describe some recent results from the SPACECAST project on modelling and forecasting the radiation belts, and modelling solar energetic particle events. We describe the SPACECAST forecasting system that uses physical models that include wave-particle interactions to forecast the electron radiation belts up to 3 h ahead. We show that the forecasts were able to reproduce the >2 MeV electron flux at GOES 13 during the moderate storm of 7-8 October 2012, and the period following a fast solar wind stream on 25-26 October 2012 to within a factor of 5 or so. At lower energies of 10- a few 100 keV we show that the electron flux at geostationary orbit depends sensitively on the high-energy tail of the source distribution near 10 RE on the nightside of the Earth, and that the source is best represented by a kappa distribution. We present a new model of whistler mode chorus determined from multiple satellite measurements which shows that the effects of wave-particle interactions beyond geostationary orbit are likely to be very significant. We also present radial diffusion coefficients calculated from satellite data at geostationary orbit which vary with Kp by over four orders of magnitude. We describe a new automated method to determine the position at the shock that is magnetically connected to the Earth for modelling solar energetic particle events and which takes into account entropy, and predict the form of the mean free path in the foreshock, and particle injection efficiency at the shock from analytical theory which can be tested in simulations.

Irradiação gama para mutagênese in vitro em bananeira 'Terra Maranhão'

O objetivo deste trabalho foi avaliar a sobrevivência de plantas e brotos bem como a redução no porte de bananeira da cultivar Terra Maranhão sob doses crescentes de radiação gama. Plantas in vitro foram irradiadas com diferentes doses de raios gama - 0, 20, 30, 40 e 60 kGy - e posteriormente avaliadas quanto à taxa de multiplicação. As doses de 20 e 30 kGy foram as mais indicadas para uso na cultivar Terra Maranhão, pois essas intensidades de irradiação proporcionaram os maiores valores do número de brotos e do índice de sobrevivência.

Intercepted solar radiation by maize crops subjected to different tillage systems and water availability levels

The objective of this work was to evaluate changes in the photosynthetic photon flux density (PPFD) interception efficiency and PPFD extinction coefficient for maize crop subjected to different soil tillage systems and water availability levels. Crops were subjected to no-tillage and conventional tillage systems combined with full irrigation and non-irrigation treatments. Continuous measurements of transmitted PPFD on the soil surface and incoming PPFD over the canopy were taken throughout the crop cycle. Leaf area index and soil water potential were also measured during the whole period. Considering a mean value over the maize cycle, intercepted PPFD was higher in the conventional tillage than in the no-tillage system. During the initial stages of plants, intercepted PPFD in the conventional tillage was double the PPFD interception in the no-tillage treatment. However, those differences were reduced up to the maximum leaf area index, close to tasseling stage. The lowest interception of PPFD occurred in the conventional tillage during the reproductive period, as leaf senescence progressed. Over the entire crop cycle, the interception of PPFD by the non-irrigated plants was about 20% lower than by the irrigated plants. The no-tillage system reduced the extinction coefficient for PPFD, which may have allowed a higher penetration of solar radiation into the canopy

A numeric model to simulate solar individual ultraviolet exposure.

Exposure to solar ultraviolet (UV) light is the main causative factor for skin cancer. UV exposure depends on environmental and individual factors. Individual exposure data remain scarce and development of alternative assessment methods is greatly needed. We developed a model simulating human exposure to solar UV. The model predicts the dose and distribution of UV exposure received on the basis of ground irradiation and morphological data. Standard 3D computer graphics techniques were adapted to develop a rendering engine that estimates the solar exposure of a virtual manikin depicted as a triangle mesh surface. The amount of solar energy received by each triangle was calculated, taking into account reflected, direct and diffuse radiation, and shading from other body parts. Dosimetric measurements (n = 54) were conducted in field conditions using a foam manikin as surrogate for an exposed individual. Dosimetric results were compared to the model predictions. The model predicted exposure to solar UV adequately. The symmetric mean absolute percentage error was 13%. Half of the predictions were within 17% range of the measurements. This model provides a tool to assess outdoor occupational and recreational UV exposures, without necessitating time-consuming individual dosimetry, with numerous potential uses in skin cancer prevention and research.

Centre d’Assistència Primària, Aparcament i Urbanització exterior al solar d'equipament Can Bruguera, Vilassar de Dalt

Award-winning

Forecasting the Earth"s radiation belts and modeling solar energetic particle events: Recent results from SPACECAST

High-energy charged particles in the van Allen radiation belts and in solar energetic particle events can damage satellites on orbit leading to malfunctions and loss of satellite service. Here we describe some recent results from the SPACECAST project on modelling and forecasting the radiation belts, and modelling solar energetic particle events. We describe the SPACECAST forecasting system that uses physical models that include wave-particle interactions to forecast the electron radiation belts up to 3 h ahead. We show that the forecasts were able to reproduce the >2 MeV electron flux at GOES 13 during the moderate storm of 7-8 October 2012, and the period following a fast solar wind stream on 25-26 October 2012 to within a factor of 5 or so. At lower energies of 10- a few 100 keV we show that the electron flux at geostationary orbit depends sensitively on the high-energy tail of the source distribution near 10 RE on the nightside of the Earth, and that the source is best represented by a kappa distribution. We present a new model of whistler mode chorus determined from multiple satellite measurements which shows that the effects of wave-particle interactions beyond geostationary orbit are likely to be very significant. We also present radial diffusion coefficients calculated from satellite data at geostationary orbit which vary with Kp by over four orders of magnitude. We describe a new automated method to determine the position at the shock that is magnetically connected to the Earth for modelling solar energetic particle events and which takes into account entropy, and predict the form of the mean free path in the foreshock, and particle injection efficiency at the shock from analytical theory which can be tested in simulations.

Fachada solar como pieza singular de arquitectura sostenible

Articulo sobre la importancia de las energias renovables y su integración arquitectónica en el camino hacia una arquitectura sostenible. Descripción y evaluación del proyecto Fachada Solar SCHOTT Iberica.