Dinâmica do sistema binário Plutão-Caronte

Pós-graduação em Física - FEG

Semi-analytical study of the rotational motion stability of artificial satellites using quaternions

This study at aims performing the stability analysis of the rotational motion to artificial satellites using quaternions to describe the satellite attitude (orientation on the space). In the system of rotational motion equations, which is composed by four kinematic equations of the quaternions and by the three Euler equations in terms of the rotational spin components. The influence of the gravity gradient and the direct solar radiation pressure torques have been considered. Equilibrium points were obtained through numerical simulations using the softwares Matlab and Octave, which are then analyzed by the Routh-Hurwitz Stability Criterion.

Comportamento térmico de coberturas em camadas duplas e estudo da substituição da cama por piso plástico na qualidade do ar, desempenho e índice de lesões em frangos de corte

Pós-graduação em Zootecnia - FCAV

Water use of Juniperus virginiana trees encroached into mesic prairies in Oklahoma, USA

Juniperus virginiana (eastern redcedar) is encroaching into mesic prairies of the southern Great Plains, USA, and is altering the hydrologic cycle. We used the thermal dissipation technique to quantify daily water use of J. virginiana into a mesic prairie by measuring 19 trees of different sizes from different density stands located in north-central Oklahoma during 2011. We took the additional step to calibrate our measurements by comparing thermal dissipation technique estimates to volumetric water use for a subset of trees. Except for days with maximum air temperature below -3 degrees C, J. virginiana trees used water year round, reached a peak in late May, and exhibited reduced water use in summer when soil water availability was low. Overall daily average water use was 24 l (+/- 21.81 s.d.) per tree. Trees in low density stands used more water than trees with similar diameters from denser stands. However, there was no difference in water use between trees in different density stands when expressed on a canopy area basis. Approximately 50% of variation in water use that remained after accounting for the factors site, tree, and day was explained using a physiologically-based model that included daily potential evapotranspiration, maximum vapour pressure deficit, maximum temperature, solar radiation, and soil water storage between 0 and 10 cm. Our model suggested that a J. virginiana woodland with a closed canopy is capable of transpiring almost all precipitation reaching the soil in years with normal precipitation, indicating the potential for encroachment to reduce water yield for streamflow and groundwater recharge. Copyright (C) 2013 John Wiley & Sons, Ltd.

On the effects of each term of the geopotential perturbation along the time I: Quasi-circular orbits

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Modelagem e simulação numérica de um sistema de refrigeração por absorção utilizando o par H2O-LiBr

The term refrigeration solar refers to any air conditioning system that uses solar energy as a primary energy source. The use of solar radiation for cooling purposes is divided according to their technological possibilities which are distinguished from one another as the way that energy is involved in the cycle, work or heat. The first case is related to vapor compression cycles, in which the work input is provided by the photovoltaic conversion of solar energy into electrical energy. In the second case, an absorption refrigeration cycle is used and the thermal energy collected from the solar radiation is provided at the generator of this cycle.. In this work a system with an absorption cycle using the pair BrLi-water, using solar energy as input is modeled. It is considered a simple refrigeration cycle whose the equations of mass and energy conservation in each component are developed in order to obtain an algebraic equation set and a simulation routine using the EES software. Although the simulation operates under certain specified thermal load it is possible to estimate the necessary areas of heat exchangers and solar collectors

Cidades sustentáveis: análise comparativa com cidades contemporâneas

Currently the world is under an energy revolution, every day more technologies are developed in order to better use the energy for having better energy efficiency of equipment and processes with minimal environmental degradation. Taking into account that thousands of people live in built environments in the context of cities and that the energy flow to this location is significant, it is important to study the built environment as a potential source of savings, energy recovery and regeneration, because cities are the major bottlenecks energetic. Therefore, this study aimed to examine and to list the most important and promising technologies to be used in the built environment to collect or save energy that would be wasted, such as clothes that generate energy through movement or solar incidence, facades of buildings that generate energy due to solar radiation, fitness centers that produce electricity due to the rotation used in fitness equipment for athletes, elevators that take advantage of the potential energy or use it more rationally, generators that take advantage of energy vibrational, and finally more sustainable vehicles with higher performance and less degrading the environment. The information and results obtained from this study show that the technologies used to harness energy before lost are increasingly evident and also is increased the progress relative to the energy use in a urban context. In the closure, a comparison of energy expenditure between a city that uses some of these sustainable technologies and another of the same size with conventional habits is presented

Análise da estabilidade do movimento rotacional de satélites artificiais com quatérnions e sob a influência de torques externos

The aim of this work is to analyze the stability of the rotational motion’s artificial satellite using the Routh Hurwitz Algorithm (CRH) and the quaternions to describe the satellite’s attitude. This algorithm allows the investigation of the stability of the motion using the coefficients of the characteristic equation associated with the equation of the rotational motion in the linear form. The equations of the rotational motion are given by the four cinematic equations for the quaternion and the three equations of Euler for the spin velocity’s components. In the Euler equations are included the components of the gravity gradient torque (TGG) and the solar radiation torque (TRS). The TGG is generated by the difference of the Earth gravity force direction and intensity actuating on each satellite mass element and it depends on the mass distribution and the form of the satellite. The TRS is created by changing of the linear momentum, which happens due to the interactions of solar photons with the satellite surface. The equilibrium points are gotten by the equation of rotational motion and the CRH is applied in the linear form of these equations. Simulations are developed for small and medium satellites, but the gotten equilibrium points are not stable by CRH. However, when some of the eigenvalues of the characteristic equation are analyzed, it is found some equilibrium points which can be pointed out as stables for an interval of the time, due to small magnitude of the real part of these eigenvalue

Avaliação da atividade antioxidante, fotoprotetora e antiglicação dos extratos de folhas e frutos de espécies da família Annonaceae

Pós-graduação em Biociências - FCLAS

Integridade dos dados meteorológicos obtidos por duas estações meteorológicas automatizadas

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

O assoalhamento em Bokermannohyla alvarengai (Anura, Hylidae): história natural e adaptações morfo-fisiológicas

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

Análise espacial e temporal da precipitação, do material particulado e da radiação global em municípios paulistas

Pós-graduação em Engenharia Mecânica - FEG

Estimation methods of reference evapotranspiration (ETo) for Uberlândia -MG

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.

Trichomes related to an unusual method of water retention and protection of the stem apex in an arid zone perennial species

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Study of some strategies for disposal of the gnss satellites

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)