845 resultados para distâncias de Mahalanobis


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV

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The present study aimed to compare the planimetric survey data of an area equivalent to a small rural property, through values of longitudes e latitudes obtained by a GPS navigation with a conventional survey data. The value of the area obtained with the navigation receiver showed a small difference when compared with the conventional system. Points located under large vegetal cover had impaired reading of coordinates. The navigation receiver can be used to get measurements inside the property for planning purposes and also for measuring he land perimeter, but not for legal purposes. The Google planimeter result in the same area as the one from the conventional survey data.

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The aim of this study was to build and validate a low cost reduced-scale wind tunnel for drift evaluation on pesticide application technology. The work was carried out at the NEMPA - Núcleo de Ensaio de Máquinas e Pneus Agroflorestais (NEMPA), FCA/UNESP, Departamento de Engenharia Rural, Botucatu/SP, Brazil. The wind tunnel main characteristics were an open circuit and a closed working section with a fan blowing air into the tunnel. Screens were fitted downstream after the fan in order to stabilize the air flow on the working section. The tunnel was built with 3.0 mm eucalyptus hardboard, with a total length of 4.8 m and a squared section of 0.56 m. The air flow was provided by a 180 W axial fan. The system was adjusted and calibrated to provide a laminar and stable flow at 2.0 m s-1. Validation studies were carried out by using a Teejet XR 8003 flat fan nozzle at 200 kPa (medium droplets) to apply a spray solutions containing water plus a food dye (Blue FDC) at 0,6% m v-1 mixed with two adjuvants: a polymer based anti drift formulation at 0,06% m v-1 and a sodium lauryl ether sulfate based surfactant at 0,2% v v-1. After a 10-second application the drift was collected on nylon strips transversally fixed along the tunnel at different distances from the nozzle and different high from the bottom part of the tunnel. Drift deposits were evaluated by spectrophotometry. The wind tunnel had low levels of turbulence and high repeatability of the data, which means that the flow was uniform and able to be used for carrying out measures to estimate drift. The validation results showed that the tunnel was effective to enable comparative drift measurements on the spray solution used in this work making possible the evaluation of drift risk potential under those spray technologies. The use of an adjuvant based on a polymer reduced the amount of drift from the nozzle compared to the surfactant.

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The aim of this work was to evaluate the effect of the addition of different surfactants in physical and chemical properties of spray solutions, droplets spectra and drift potential on agricultural spraying. The surfactants and concentrations (v v-1) were: Haiten (0.1%), Antideriva and Intec (0.05% and 0.1%). The following characteristics were analyzed: surface tension, viscosity, density and electric conductivity. The droplet size spectrum was determined by a laser particle analyzer (Mastersizer S®, version 2.15) including measurements of volume medium diameter (VMD), the percent of droplets below 50 and 100 μm (V50 e V100) and index span. In order to estimate the drift potential, a series of wind tunnel tests were performed with a Teejet XR 8003 flat fan nozzle at 200 kPa (medium droplets) used to apply the spray solutions containing water, the adjuvants and a food color dye (Brilliant blue FD & C no 1) at 0,6% m v-1. The drift was collected on nylon strips transversally fixed along the tunnel at different distances from the nozzle and different high from the bottom part of the tunnel. Drift deposits were evaluated by spectrophotometry. The results showed that the addition of adjuvants changed physical and chemical properties of spray solutions in different magnitudes according to the surfactant. Surfactants changed the droplet spectrum and drift potential, indicating that higher VMD and smaller V100 induced higher percentage of drift.

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Over the past few years, the area of planted forests has expanded considerably in Brazil, reaching a level of 6.3 million hectares, which represents approximately 0.7% of the country, mainly with some species of the Eucalyptus genus. However, due to the global concern with biological invasions by exotic species, risk assessment is necessary to evaluate the potential of Eucalyptus species escaping cultivated stands and invading surrounding native ecosystems. Seedlings by natural regeneration from Eucalyptus grandis and E. urophylla, pure and hybrids between the two species were evaluated, by assessing natural regeneration of Eucalyptus in 18 sites located in Brazilian states with plantation forest tradition (Minas Gerais, São Paulo, Rio Grande do Sul and Espírito Santo). Sample plots were installed in the planted stands, along forest roads and in a nearby pasture or native vegetation.,at different distances from the Eucalyptus stands. Regeneration of Eucalyptus was not recorded in 90% of the plots installed outside the eucalipt stands. However, seedlings of eucalypts were observed in 29% of the plots within the commercial stands (mean density of 37 seedlings per hectare) and 40% of the plots located along forest roads (157 seedlings per hectare on average), but no adult plants by natural regeneration were found. The seedlings of eucalypt species studied rarely were found beyond the limits of the cultivated areas. In the planted stands or along forest roads, eucalypts can germinate, but the seedlings apparently do not establish. So the potential for invasion by seeds produced in commercial plantations of Eucalyptus is low.

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Pós-graduação em Ciência e Tecnologia Animal - FEIS

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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

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

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Pós-graduação em Agronomia (Horticultura) - FCA