Concepção e simulação de uma chaminé solar

The present work intends to study some fluid dynamic and heat transfer aspects of a solar chimney, aiming at a preliminary design of a facility. Some definitions and concepts of this system are presented. The simulation was performed based on a theoretical model validated with measurements of a prototype in Manzanares, Spain. Using the same theoretical model and some considerations, dimensions on a small scale are applied, making the model more interesting from its constructive aspect. The results show the behavior of the air velocity inside the chimney and illustrate some values of two preselected turbines. This technology looks promising in Brazilian territory due to high levels of solar radiation

Estimativa da Radiação Solar em Presidente Prudente – SP nos anos de 1999-2007

The wide territorial extension of Brazil derails the installation and maintenance of instruments for measuring solar radiation, which makes necessary the development and application of models that are able to estimate reliable and sufficient data for many different activities that use such data. And these, in most cases, are estimated from the Ångström equation. Based on this model, this project aimed to estimate the global solar radiation at Presidente Prudente-SP, Brazil, using daily data from 1999 to 2007. The solar radiation data have been extracted from the paper tapes of actinograph bi-metallic (Robitsch) daily records at the meteorological station in the Faculty of Science and Technology, UNESP. These tapes were scanned, resulting in digital images with x and y coordinates pairs (x = time; y = solar radiation, cal/min.cm²). The daily global solar radiation is the area under the curve of the image. This value has been calculated by computer algorithms. After the acquisition and calculation of the values needed to develop the Ångström equation have been determined the constants a and b, using linear regression between the values of Rg/R0 (solar radiation/solar radiation on a horizontal surface at the top of atmosphere), as ordered, and n/N (number of hours of sunshine/day length in hours) as abscissa. The slope of the line will be the constant b and the linear coefficient, the constant a. The estimated results were compared to the observed using the Kolmogorov-Smirnov test, realizing that the models can be accepted. So, the equation to aim the solar global radiation is: Rg = R0 (0,2662+0,3592 n/N)

Analysis of hourly global, direct and diffuse solar radiations attenuation as a function of optical air mass

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise numérica de uma geometria de coletor solar para sistemas de aquecimento de água

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise diferencial da potência máxima gerada por um sistema solar fotovoltaico

The Earth receives annually 1,5.1018 kWh of solar energy, which corresponds to 1000 times the world energy consumption in this period. This fact comes out that, besides being responsible for the maintenance of life on Earth, the solar radiation is in an inexhaustible energy source, with an enormous potential for use by systems capture and conversion into another form of energy. In many applications of low power systems that convert light directly into electricity, called photovoltaic advantageously replace other means of production processes, where its distribution is very significant. The determination of the power generated by such a system is of paramount importance for the design energy of its implementation and evaluation of the system itself. This study aims to determine a relationship between the maximum power generated by solar photovoltaic and characteristic parameters of the generator. This relationship allows to evaluate the performance of such a system. For simulations of the developed equations were used 3 photovoltaic modules with an output of 100 Wp each, and data collection was performed during one year by enrolling in addition to meteorological data, solar irradiance incident on the modules.

Estimativa da radiação solar global em estufa de polietileno a partir do brilho solar

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estimativa da irradiação solar global pelo método de Angstrom-Prescott e técnicas de aprendizado de máquinas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Regiões de estabilidade no ambiente de um sistema de asteroide triplo

This work was developed from the study by Araujo, R.A.N. et al. Stability regions around the components of the triple system 2001 SN263. (Monthly Notices Of The Royal Astronomical Society, 2012, v. 423(4), 3058-3073 p.) where it was studied the stable and unstable regions system (2001 SN263), which is a triple asteroid system, and these are celestial orbiting our sun. Being close to the Earth is characterized as NEA (Near-Earth Asteroids), asteroids and which periodically approach the Earth's orbit, given that there is great interest in the study and exploitation of these objects, it is the key can carry features that contribute to better understand the process of formation of our solar system. Study the dynamics of bodies that govern those systems proves to be greatly attractive because of the mutual gravitational perturbation of bodies and also by external disturbances. Recently, NEA 2001 SN263 was chosen as a target of Aster mission where a probe is sent for this triple system, appearing therefore the need for obtaining information for characterizing stable regions internal and external to the system, with respect to the effects of radiation pressure. First, this study demonstrated that the integrator used showed satisfactory results of the orbital evolution of bodies in accordance with previous studies and also the characterization of stable and unstable regions brought similar results to the study by Araujo et al. (2012). From these results it was possible to carry out the implementation of the radiation pressure in the system in 2001 SN263, in a region close to the central body, where the simulations were carried out, which brought as a result that the regions before being characterized as stable in unstable true for small particles size from 1 to 5 micrometers. So the next orbital region to the central body and the ... ( Complete abstract click electronic access below)

Effect of environmental variables on buffaloes physiology

The objective of this work was to evaluate the effect of environmental variables on dairy buffaloes physiology in two different places after milking, shaded plus artificial ventilation and another one non-shaded, in Ribeira Valley, São Paulo State, Brazil. Data on the respiratory rate (RR) and the surface temperature (ST) at udder, neckmiddle, forehead, back middle and rump were collected in 12 dairy buffaloes at autumn. In the same way, it were recorded the black globe temperature in the sun (GTS) and in the shade (GTNS), air temperature and wind speed at padronized height of 1.60 meters. All data were collected at 10:30am and 1:30pm. The results showed statistical difference among black globe temperature, wind speed, RR and ST (P<0.01) in two treatments.The results showed the necessity of protection against the solar radiation in the buffaloes, even in periods of warm climates.

Mathematical analysis of maximum power generated by photovoltaic systems and fitting curves for standard test conditions

The rural electrification is characterized by geographical dispersion of the population, low consumption, high investment by consumers and high cost. Moreover, solar radiation constitutes an inexhaustible source of energy and in its conversion into electricity photovoltaic panels are used. In this study, equations were adjusted to field conditions presented by the manufacturer for current and power of small photovoltaic systems. The mathematical analysis was performed on the photovoltaic rural system I- 100 from ISOFOTON, with power 300 Wp, located at the Experimental Farm Lageado of FCA/UNESP. For the development of such equations, the circuitry of photovoltaic cells has been studied to apply iterative numerical methods for the determination of electrical parameters and possible errors in the appropriate equations in the literature to reality. Therefore, a simulation of a photovoltaic panel was proposed through mathematical equations that were adjusted according to the data of local radiation. The results have presented equations that provide real answers to the user and may assist in the design of these systems, once calculated that the maximum power limit ensures a supply of energy generated. This real sizing helps establishing the possible applications of solar energy to the rural producer and informing the real possibilities of generating electricity from the sun.

Curvas de crescimento do fruto de cafeeiro cv. Obatã IAC 1669-20 em diferentes alinhamentos de plantio

The growth of the coffee fruit is highly dependent on physiological and environmental factors. Environmental factors that most influence the yield of coffee during the critical growth stages are the minimum and maximum temperatures of air, which are affected by solar radiation and depend on the apparent path of the sun. This research work correlated dry mass versus fresh mass, and, fresh and dry mass as function of days after flowering of fruit coffee cv. Obata IAC 1669-20 planted in three different alignments based on the apparent trajectory of the sun, in Jaboticabal, SP. The planting was aligned according to the apparent path of the sun. There were three treatments with four replications, a total of twelve plots, each plot with one hundred plants of coffee, each treatment corresponded to an alignment of planting. The three alignments used showed no differences with respect the average fresh and dry mass. The growth rate of fruit, in fresh weight, was higher in the exponential phase, and in dry mass was higher in the linear stage. The dry weight (DW) can be estimated from the fresh weight (FW) using the model: DW = A1*exp(FW/t1). The sigmoidal model that represents the fruit growth in of coffee plants in fresh and/or dry mass in terms of days after flowering (DAF) was: FW(DW) = A2+[(A1-A2)/(1+exp(DAF-x0)/dx)].

Influência do alinhamento de plantio na severidade da mancha-preta-dos-citros, produção e qualidade do suco

Os níveis de incidência e severidade de sintomas das doenças resultam da interação hospedeiro-patógeno-ambiente. Nesse contexto, a favorabilidade do ambiente, em particular, depende do nível de umidade, intensidade de radiação solar, luminosidade e molhamento foliar, dentre outros fatores. Por outro lado, a magnitude de expressão desses fatores é dependente do ciclo e porte das plantas, e possivelmente, também, do alinhamento de plantio. No presente estudo, foi avaliada a influência dos alinhamentos de plantio N-S, L-O, NE-SO E NO-SE no desempenho agronômico de plantas de laranjas 'Natal'e 'Valência', assim como na severidade de sintomas da mancha-preta-dos-citros (MPC), causada por Guignardia citricarpa. Para tal, foram selecionadas cinco propriedades distribuídas ao longo do cinturão citrícola paulista, de talhões semelhantes, a partir das quais foram coletadas amostras de 50 frutos, em dez plantas de mesma linha, da região central dos mesmos. Tais frutos foram levados para laboratórios e analisados quanto aos níveis de severidade de sintomas da MPC, produção e qualidade do suco. Constatouse que os frutos oriundos de pomares implantados no alinhamento N-S apresentavam menores níveis de severidade da doença, enquanto no alinhamento NE-SO, os mais elevados. Propriedades localizadas mais ao sul do Estado de São Paulo apresentaram menores níveis de doença, provavelmente em consequência da ocorrência recente da doença em tais áreas. em relação à produção, os alinhamentos de plantio N-S e L-O proporcionaram maior número de frutos por planta, assim como quanto ao número de caixas por planta. Por outro lado, a menor produção foi verificada nos alinhamentos NO-SE. em relação à qualidade do suco, não foi possível estabelecer um padrão definido em termos de ratio e ºBrix e os respectivos alinhamentos de plantio. Foi verificado que os valores de ratio foram menores nos frutos de pomares localizados mais ao sul do Estado, de maiores latitudes.

Características do pelame de vacas Holandesas em ambiente tropical: um estudo genético e adaptativo

As características do pelame (espessura da capa, comprimento médio dos pêlos, número de pêlos por unidade de área, densidade de massa dos pêlos, ângulo de inclinação dos pêlos com respeito a superfície da epiderme e diâmetro médio do pêlos) foram avaliadas em 973 vacas da raça Holandesa, entre novembro de 2000 e abril de 2001, numa área localizada 20cm abaixo da coluna vertebral, no centro do tronco, tanto nas malhas brancas como nas negras. As amostras de pêlos foram obtidas com um alicate comum adaptado. O método da Máxima Verossimilhança Restrita (REML) foi usado para estimar os componentes de variância e covariância sob modelo animal, sendo empregado o sistema MTDFREML. Os resultados mostraram que as características do pelame preto são diferentes das do branco, quando os animais são criados em ambiente tropical. O pelame preto apresentou-se menos denso, com pêlos mais curtos e grossos devido à maior necessidade de perder calor, enquanto que, o pelame branco é mais denso e com pêlos mais compridos, oferecendo uma melhor proteção contra à radiação solar direta. A seleção de vacas predominantemente negras pode ser uma boa escolha para aumentar a resistência do gado Holandês às condições do ambiente tropical, principalmente à radiação solar, quando esses animais são criados a campo, devido a que a epiderme sob esse tipo de malhas é altamente pigmentada. Tal seleção pode ser facilmente realizada, considerando a alta herdabilidade (h²=0,75) para a proporção de malhas negras. Esta seleção deve ser realizada no sentido de um pelame menos denso, com pêlos curtos e grossos favorecendo as perdas de calor sensível e calor latente.

Florescimento em cana-de-açúcar

O florescimento da cana-de-açúcar é um processo fisiológico complexo formado por vários estádios de desenvolvimento, e cada estádio tem a sua própria necessidade ambiental e fisiológica. Os fatores externos relacionados com o florescimento são: fotoperíodo, temperatura, umidade e radiação solar, além da fertilidade do solo. Por outro lado, os fatores internos envolvem fitocromo, hormônios, florígeno, ácidos nucleicos, dentre outros. A intensidade do processo de florescimento e as consequências na qualidade da cana-de-açúcar variam com a variedade e com o clima. A redução do volume de caldo é o principal fator no qual o florescimento interfere, resultante do aumento do teor de fibras. Como as demais Poaceae, a cana-de-açúcar floresce, frutifica e morre, garantindo a perpetuação da espécie. Dessa forma, o homem procura interferir na natureza tentando evitar o florescimento da cana-de-açúcar, seja por meio de melhoramento genético ou por meio de reguladores vegetais. em áreas comerciais de produção de cana-de-açúcar, onde há condições ideais para o florescimento da cultura, é recomendado o uso de variedade com potencial menos florífero. E, quando não é possível esse manejo varietal, o uso de inibidores do florescimento é a melhor alternativa para evitar mais perdas no conteúdo de sacarose.

Improving photoprotection of Beauveria bassiana conidia for biological control of the cactus pest Dactylopius opuntiae in the semiarid region northeast of Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)