Agricultura: a pequena produ????o, tecnologia e meio-ambiente

Trata-se do desenvolvimento de alternativas tecnol??gicas e sistemas agr??colas sustent??veis, capazes de fixar os pequenos produtores dos tr??picos ??midos em suas terras, que ?? um dos pontos fundamentais para se reduzir o ritmo de desmatamento e para se promover uma estrat??gia de desenvolvimento rural mais balanceada nessas regi??es. Algumas das experi??ncias que ocorreram em diversas regi??es da Am??rica Latina tropical ??mida s??o aqui resgatadas e avaliadas com o intuito de embasar as discuss??es relativas ?? quest??o tecnol??gica da pequena produ????o nessas ??reas. Discute-se em particular a relev??ncia e a viabilidade da implementa????o nessas regi??es de Farming Systems Research (FSR), uma metodologia alternativa para a Pesquisa agr??cola e, em particular, para a gera????o de tecnologia apropriada para pequenos produtores

Agricultura: a pequena produção, tecnologia e meio-ambiente

Trata-se do desenvolvimento de alternativas tecnológicas e sistemas agrícolas sustentáveis, capazes de fixar os pequenos produtores dos trópicos úmidos em suas terras, que é um dos pontos fundamentais para se reduzir o ritmo de desmatamento e para se promover uma estratégia de desenvolvimento rural mais balanceada nessas regiões. Algumas das experiências que ocorreram em diversas regiões da América Latina tropical úmida são aqui resgatadas e avaliadas com o intuito de embasar as discussões relativas à questão tecnológica da pequena produção nessas áreas. Discute-se em particular a relevância e a viabilidade da implementação nessas regiões de Farming Systems Research (FSR), uma metodologia alternativa para a Pesquisa agrícola e, em particular, para a geração de tecnologia apropriada para pequenos produtores

Eficiência da redução da dose e do volume de calda de aplicação de herbicidas de pós-emergência de ação total no controle de plantas daninhas na cultura de soja [Glycine max (L.) Merrill].

bitstream/item/134542/1/ID12973-1993-1994sojaresultados-p94-96.pdfTrabalho apresentado na XXII Reunião de Pesquisa de Soja da Região SSul, Cruz Alta, 1994

Study of effect of flow parameters on base pressure in a suddenly expanded duct at supersonic mach number regimes using CFD and design of experiments

Effectiveness of active control of micro jets has been examined by conducting experiments through an abruptly expanded axi-symmetric duct in a view to control base pressure. For this purpose, 1mm orifice diameter micro jets have been deployed at an interval of 900 along the exit diameter of the nozzle. The experiments have been conducted by considering three flow parameters at three levels. Mach number (M), length to diameter (L/D) ratio and area ratio (AR) are the three parameters used to conduct and analyze the flow experiments. Base pressure is considered to be the response variable. The experimentation has been carried out for two cases, i) without active control; ii) with active control. An L9 orthogonal array has been implemented to plan the experiments. It is observed that the control becomes effective for lower area ratios when compared to the higher ones. In addition to this, at high area ratios suction at the base decreases and hence base pressure continuous to diminish with increasing L/D until it reaches a value of L/D=6. The obtained experimental results are subjected to multiple linear regression analysis and Analysis of variance (ANOVA). The performances of the two linear regression models were tested for their prediction accuracy with the help of 15 random test cases. It is observed that, both linear regression models for base pressure without and with control are statistically adequate and capable of making accurate predictions. Furthermore, this work also concludes that, Mach number is the most significant factor affecting base pressure followed by area ratio and L/D ratio for both cases of experimentation. The obtained experimental results are further validated by CFD analysis and are found to be in good concurrence with each other

Base pressure behaviour in a suddenly expanded duct at supersonic mach number regimes using Taguchi design of experiments

Experimental investigations are carried out to study the control of base pressure without and with the use of micro-jets through suddenly expanded axi-symmetric passage in the supersonic regime. Four micro jets having an orifice diameter of 1mm were located at 90◦ intervals. In the base area, active controls jets have been placed on a pitch of a circle diameter that is 1.3 times the exit diameter of the nozzle. The jets were dispensed abruptly into the axi-symmetric tube maintained at a cross-sectional area of 4.84 times the exit nozzle area. The variation of base pressure as a function of flow control parameters namely Mach number, nozzle pressure ratio (NPR) and length to diameter) ratio (L/D) are evaluated experimentally. This study also assesses the impact of flow control variables on base pressure for two cases viz. with control and without control respectively. An L9 orthogonal array of Taguchi and the analysis of variance were employed to investigate the percentage of contribution of these parameters and their interactions affecting the base pressure. The correlations between the various factors affecting the base pressure were obtained by using multiple linear regression equations. Confirmation tests were conducted in order to test the developed linear regression equations for their practical significance. Both the regression models were found to be significant and reliable with a percentage deviation lying in the range of −6.12% to 10.26% for base pressure without control and −13.92% to 6.58% for base pressure with control. Analysis of variance was also performed in order to determine the statistical significance of each parameter on the total variability of base pressure. The study concluded that Mach number is the most influential parameter affecting base pressure followed by NPR and L/D

Desinfestação de erva-mate in vitro.

EVINCI. Resumo 016