211 resultados para Solar radiation pressure


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One approach to verify the adequacy of estimation methods of reference evapotranspiration is the comparison with the Penman-Monteith method, recommended by the United Nations of Food and Agriculture Organization - FAO, as the standard method for estimating ET0. This study aimed to compare methods for estimating ET0, Makkink (MK), Hargreaves (HG) and Solar Radiation (RS), with Penman-Monteith (PM). For this purpose, we used daily data of global solar radiation, air temperature, relative humidity and wind speed for the year 2010, obtained through the automatic meteorological station, with latitude 18° 91' 66 S, longitude 48° 25' 05 W and altitude of 869m, at the National Institute of Meteorology situated in the Campus of Federal University of Uberlandia - MG, Brazil. Analysis of results for the period were carried out in daily basis, using regression analysis and considering the linear model y = ax, where the dependent variable was the method of Penman-Monteith and the independent, the estimation of ET0 by evaluated methods. Methodology was used to check the influence of standard deviation of daily ET0 in comparison of methods. The evaluation indicated that methods of Solar Radiation and Penman-Monteith cannot be compared, yet the method of Hargreaves indicates the most efficient adjustment to estimate ETo.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Notwithstanding the solar radiation is recognized as a detrimental factor to the thermal balance and responses of animals on the range in tropical conditions, studies on the amount of thermal radiation absorbed by goats therein associated with data on their production and heat exchange are still lacking. Metabolic heat production and the heat exchange of goats in the sun and in the shade were measured simultaneously, aiming to observe its thermal equilibrium. The results showed that black goats absorb twice as much as the white goats under intense solar radiation (higher than 800 W m(-2)). This observation leads to a higher surface temperature of black goats, but it must not be seen as a disadvantage, because they increase their sensible heat flow in the coat-air interface, especially the convection heat flow at high wind speeds. In the shade, no difference between the coat colours was observed and both presented a lower absorption of heat and a lower sensible heat flow gain. When solar radiation levels increases from 300 to 1000 W m(-2), we observed an increase of the heat losses through latent flow in both respiratory and cutaneous surface. Cutaneous evaporation was responsible for almost 90 % of the latent heat losses, independently of the coat colour. Goats decrease the metabolic heat production under solar radiation levels up to 800 W m(-2), and increase in levels higher than this, because there is an increase of the respiratory rate and of the respiratory flow, but the fractions of consumed oxygen and produced carbon dioxide are maintained stable. The respiratory rate of black goats was higher than the white ones, under 300 W m(-2) (55 and 45 resp min(-1)) and 1000 W m(-2) (120 and 95 resp min(-1), respectively). It was concluded that shade or any protection against solar radiation levels above 800 Wm(-2) is critical to guarantee goat's thermal equilibrium. Strategies concerning the grazing period in accordance with the time of the day alone are not appropriate, because the levels of radiation depend on the latitude of the location.

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Introduction: much studies regarding risk factors associated with oral cancer. Factors such as smoking and alcohol and solar radiation are well established, but others, such as bacterial influence in the development or progression of a tumor still remain unexplained. Interest in the possible relationship between bacteria and different stages of cancer development has increased since the classification of H. pylori by the WHO as a definite carcinogen. Subsequently, links between infection and the onset of cancer in various sites in the body were discovered. Review of literature: this literature review attempts to show the influence of poor oral hygiene, with consequent bacterial accumulation as a possible important risk factor for the initiation and development of mouth cancer, and correlate the possible mechanisms by which bacteria can initiate or promote carcinogenesis. Conclusion: there is much evidence that bacteria in the oral cavity and periodontopathic are present in tumor tissue, however, still can not affirm that these bacteria initiate or promote carcinogenesis.

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Introduction: much studies regarding risk factors associated with oral cancer. Factors such as smoking and alcohol and solar radiation are well established, but others, such as bacterial influence in the development or progression of a tumor still remain unexplained. Interest in the possible relationship between bacteria and different stages of cancer development has increased since the classification of H. pylori by the WHO as a definite carcinogen. Subsequently, links between infection and the onset of cancer in various sites in the body were discovered. Review of literature: this literature review attempts to show the influence of poor oral hygiene, with consequent bacterial accumulation as a possible important risk factor for the initiation and development of mouth cancer, and correlate the possible mechanisms by which bacteria can initiate or promote carcinogenesis. Conclusion: there is much evidence that bacteria in the oral cavity and periodontopathic are present in tumor tissue, however, still can not affirm that these bacteria initiate or promote carcinogenesis.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This paper presents the results of a study on the thermal comfort in open urban spaces, undertaken in pedestrian streets located in the three towns, Campinas, Baurú, and Presidente Prudente, in the state of Sao Paulo. The study was developed as part of a more extensive project on thermal comfort in different kinds of open public spaces in Brazil. The methodology involved monitoring the microclimatic variables (air and globe temperature, humidity, air velocity and global solar radiation), and structured interviews, in order to assess the actual thermal comfort through the Actual Sensation Vote (ASV) and the personal users’ variables. The Physiological Equivalent Temperature (PET) was also calculated. The results show different limits for neutral temperature in each city: 20-29ºC for Campinas, 21-30 ºC for Bauru and 14-24 ºC for Presidente Prudente). However, 59.5% of the total sample (308 out of 519 individuals) indicated comfort limits ranging from 18 to 26 ºC, which is consistent with the limits proposed by Monteiro and Alucci for the city of Sao Paulo. These results can contribute to evaluate the thermal quality of other public spaces in the same towns.

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Based on climatological data and energy flow, this paper analyzes the behavior observed in microclimatic an important remnant of cerrado in the São Paulo State. The seasonal climate is well marked, in the study area, with two climatic periods (one dry and one wet). The vegetation presents physiology as a function of water availability and the local thermal conditions and can be seen marked changes in the landscape due to the more or less presence of solar radiation. It’s important to understand the ecosystems behave in the context of global change. It has gained the attention of many researchers in the world.

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Pós-graduação em Zootecnia - FCAV

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Brazil is a country of continental dimensions with a large heterogeneity of climates and massive mixing of the population. Almost the entire national territory is located between the Equator and the Tropic of Capricorn, and the Earth axial tilt to the south certainly makes Brazil one of the countries of the world with greater extent of land in proximity to the sun. The Brazilian coastline, where most of its population lives, is more than 8,500 km long. Due to geographic characteristics and cultural trends, Brazilians are among the peoples with the highest annual exposure to the sun. Epidemiological data show a continuing increase in the incidence of non-melanoma and melanoma skin cancers. Photoprotection can be understood as a set of measures aimed at reducing sun exposure and at preventing the development of acute and chronic actinic damage. Due to the peculiarities of Brazilian territory and culture, it would not be advisable to replicate the concepts of photoprotection from other developed countries, places with completely different climates and populations. Thus the Brazilian Society of Dermatology has developed the Brazilian Consensus on Photoprotection, the first official document on photoprotection developed in Brazil for Brazilians, with recommendations on matters involving photoprotection.

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This work presents an analysis of the pattern variation of the sky conditions in Botucatu/SP. The classification was based on the clarness index KT. It was used in the classification a database of global solar irradiance in the horizontal, measured at Radiometric Station of UNESP in Botucatu (latitude 22.85°S, longitude 48.43°W, altitude 786 m) from 1996 to 2005. We analyzed the variations in frequency, during the photoperiod and over the year, of the sky conditions: I - Cloudy (KT < 0.35); II - party cloudy with dominance for the diffuse (0.35 < 0.55 < KT)) III - party cloudy with dominance for the clear (0.55 < KT < 0.65) and IV - clear (KT > 0.65). The frequency of sky conditions I and II are higher during the rainy season of the year and in hours close to sunrise and sunset. And it is lower during the dry season an in hours near noon, in wich there is a predominance of sky conditions III and IV. The monthly hourly frequency of sky condition I ranged from 46,91% of the photoperiod in January to 25.27% in August. And the frequency monthly daily ranged from nine days in January to three days in August. To the sky condition IV, the frequency monthly hourly ranged from 38.81% of the photoperiod in August to 18.17% im January. And the frequency monthly daily ranged from 17 days in August to three days in January.

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This paper presents the application and use of a methodology based on fuzzy theory and simulates its use in intelligent control of a hybrid system for generating electricity, using solar energy, photovoltaic and wind. When using a fuzzy control system, it reached the point of maximum generation of energy, thus shifting all energy generated from the alternative sources-solar photovoltaic and wind, cargo and / or batteries when its use not immediately. The model uses three variables used for entry, which are: wind speed, solar radiation and loading the bank of batteries. For output variable has to choose which of the batteries of the battery bank is charged. For the simulations of this work is used MATLAB software. In this environment mathematical computational are analyzed and simulated all mathematical modeling, rules and other variables in the system described fuzzy. This model can be used in a system of control of hybrid systems for generating energy, providing the best use of energy sources, sun and wind, so we can extract the maximum energy possible these alternative sources without any prejudice to the environment.

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Evaluated statistical equations estimates (based on radiometric fractions) of the hourly diffuse radiation incident on inclined surfaces for the North to 12.85, 22.85 and 32.85°, the climate and geographical conditions of Botucatu, SP. The database was generated from April/1998 to December/2007, with measures in the three tilted surfaces in different periods, but concomitant to the horizontal plane. In the validation of the equations were used indicative statistics MBE (mean absolute error), RMSE (square root mean square error) and index adjustment (d) for three inclinations and conditions of sky coverage. The increased angle of inclination of the surface led to increased scattering of hourly values for the coefficient of atmospheric transmissivity of diffuse radiation for inclined and horizontal surfaces. Estimates of diffuse radiation on the basis of hourly tilted horizontal global radiation occur for quadratic polynomial models, which adjust K'Dβ maximum values of between 0.14 and 0.30 for winter and summer when KTH varies between 0.40 and 0.66, indicating that energy, the highest values of diffuse radiation occur in partly cloudy sky conditions and / or partially open. The increase in atmospheric transmissivity decreases the performance of annual and monthly equations at all inclinations.