Paula Cristina Natalino Rinaldi

Avaliação do custo energético de diferentes operações agrícolas mecanizadas

Com o proposito de aumentar a eficiencia de uso de insumos energeticos utilizados na agricultura tropical, procurou-se determinar o custo energetico (MJ ha-1) das principais operacoes agricolas mecanizadas em quatro sistemas de preparo do solo para a semeadura do milho e quantificar sua possivel reducao, utilizando os sistemas de preparo conservacionistas, em relacao ao sistema convencional. O experimento foi conduzido na Universidade Federal de Vicosa - UFV. O delineamento experimental foi em parcelas subdivididas com quatro tratamentos e nove repeticoes, totalizando 36 parcelas experimentais. Foram avaliadas a densidade do solo, teor de agua do solo e resistencia do solo a penetracao, o consumo de combustivel e o custo energetico. O plantio direto foi o sistema que proporcionou menor consumo de combustivel, seguido pelo sistema de cultivo minimo com grade de disco leve, preparo reduzido e preparo convencional, respectivamente. O plantio direto teve um custo energetico de 52,72% do custo do sistema convencional e o cultivo minimo foi de 77,52%, possibilitando economizar entre 1216,51 e 578,39 MJ ha-1, respectivamente, equivalente a 25,45 e 12,10 L de oleo diesel para cada hectare trabalhado.

Compactação de um solo de uso florestal submetido ao tráfego de arraste de madeira

The objective of this research was to evaluate compaction of a Red-Yellow Latosol subjected to forestry traffic including two types of skidder: a wheeled-clambunk skidder and a tracked one. This study tries to remedy the lack of information on this subject, considering that mechanized traffic can result in several impacts on the environment. These impacts are related to soil compaction and water resources quality, resulting in reduction of forestry productivity. The soil physical parameters analysed were: soil dry bulk density, total porosity and soil penetrometer resistance. A 2x3x3 factorial statistical design was used, including type of skidder, pattern operation and soil depth, using the Dunnet test at 5% significance level. The statistical analysis included the test of interaction between types of machines and the number of machine travels. Results showed that the loaded wheeled-clambunk skidder traveling once or twice caused effects of compaction on soil up to 15 cm depth. In the same condition, the tracked-skidder traveling twice also produced significant effect on soil compaction. In the 15-50 cm depth, only two travels of the wheeled-clambunk skidder caused soil compaction.

Avaliação ergonômica da cabine de um trator florestal

Studies conducted by anthropometric and ergonomic assessments contribute to aid for new projects based on the design of machines and equipment. The objective of the present work was to perform an anthropometric analysis of workers who operate forest harvest machines and an ergonomic assessment of the operator cabin of a Feller-Buncher, in order to gather information needed for future modifications. Analyses were performed at CENIBRA forestry company in Minas Gerais. The anthropometric evaluation of the operators was conducted by two sets of measures, while standing and sitting. During the ergonomic assessments and measurement of controls positioning and field of view, distances were determined from the seat reference point (ARP) in three dimensions (x, y and z). The results showed that there is need for ergonomic improvements in the seat, controls, control panel, symbology commands, dials and warning lights.

Efeito do aquecimento e resfriamento de pisos no desempenho de matrizes e leitões

O ambiente da criacao intensiva de suinos influencia diretamente as condicoes de conforto e bem-estar animal; ambiente estressante provoca varias respostas, dependendo da capacidade de adaptacao do animal, e as instalacoes tem como finalidade minimizar esses problemas. Objetivou-se, com este trabalho, avaliar o comportamento fisiologico e os indices zootecnicos das matrizes e dos leitoes, com a utilizacao dos sistemas de aquecimento e resfriamento do piso. O delineamento experimental utilizado foi o inteiramente casualizado, no esquema fatorial em parcelas subdivididas, com cinco repeticoes para os tratamentos: piso aquecido para os leitoes e resfriado para as matrizes (PCARA), piso sem aquecimento para os leitoes e resfriado para as matrizes (PRCA) e piso sem modificacao (PSMCA). Foram avaliados os parâmetros termicos e fisiologicos das matrizes dos tratamentos PRCA e PCARA. O tratamento PRCA apresentou o melhor resultado, proporcionando maior conforto termico para os animais, que atingiram em media um ganho 233 gramas por dia.

Traction conditions for agricultural tractors manufactured and marketed in Brazil

In Brazil today, beyond there is no mandatory testing center, there are few studies aiming to determine the performance of agricultural tractors. Performance tests of the specimens are made by manufacturers, and because the official reports disclosure is not required, consumers have information only from the own manufacturer. Thus, this study aimed to evaluate the performance the conditions tractor of the agricultural tractors with manufactured and/or sold tires in Brazil in relation to power ranges and type of traction. To do so, from 191 agricultural tractors, we calculated the following parameters maximum traction force at DB and relative traction force/weight. Some ofthese parameters were evaluated under different soil and ballast conditions. The results showed that the power range 147 kW and 4x2 TDA traction type present the best values for estimated maximum traction power. It can be concluded that the maximum traction force is higher for the range tractors 147 kW, power over and traction type 4x2 TDA backed.