371 resultados para Eucalyptus citriodora


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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Pós-graduação em Agronomia - FEIS

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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

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In 2010, the Brazilian forest sector is represented by about 30,000 companies producing US$ 21 billion annually and account for approximately 5% of the gross domestic product (GDP) in the country. The sanding process is highly demanded in various stages of industrialization of the wood, when there is a need for a better quality surface finishing. The objective of this work was to analyze the influence of cutting speed and sandpaper granulometry on both the surface finishing of pieces of Eucalyptus grandis processed through tubular sanding and on the sanding efforts (force and power of sanding). Four cutting speeds were used (19.5, 22.7, 26 and 28.1 m/s), one advance speed (16 m/min) and three sets of sandpaper (80-100, 80-120 and 100-120) being one for chipping and another for finishing, respectively. A central data acquisition system was set up to capture the variables (cutting power, acoustic emission and vibration) in real time. The cutting force was obtained indirectly, through a frequency inverter. The roughness of the parts was measured by a roughness meter before and after sanding. The highest cutting speed used (28.1 m/s) consumed more power and generated more acoustic emission among the four speeds tested. Regarding the vibration, the lower cutting speed (19.5 m/ s) generated the highest vibration in the sander machine. It is concluded that the range of 100-120 sandpapers resulted in values of average roughness (Ra) lower than the other sets of sandpaper used, as it resulted in better surface finishing.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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

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Vegetative propagation is considered the best choice for the rapid multiplication of plant species, however, rooting may still present difficulties. Substances, such as auxins, phenolic compounds and hydrogen peroxide, are recognized as able to improve this process. The aim of the present work was to determine if hydrogen peroxide in combination with quercetin or indole butyric acid, can modify some characteristics related to rooting and development in cuttings of Eucalyptus grandis x Eucalyptus urophylla. Cuttings were periodically evaluated at 30, 60 and 90 days according to the following criteria: height, diameter and survival percentage. After planting (90 days), a destructive evaluation was performed to determine rooting percentage, average size and number of roots. Polyamines content and polyamine oxidase activity, as biochemical markers of plant development, were determined. No statistically significant differences in height, diameter, survival and rooting percentage, root length and number of roots per cuttings were found. Treatments induced a decrease in putrescine levels and polyamine oxidase activity in roots. For absence of positive responses, the use of these substances as a treatment to improve cutting production is economically unviable.

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The objective of this study was evaluate the effects of retification® temperatures and times on thickness variation from Eucalyptus grandis timber. Boards from logs of 30-year-old Eucalyptus grandis trees, from São Paulo Forest Institute in Santa Barbara, Brazil, were thermally modified at 180ºC for 2.5 hours, at 200ºC for 3.0 hours and 200ºC for 4.0 hours. The results showed that: (1) the thermally modified wood at 200°C by 3.0 to 4.0 hours showed increased thickness between 0.698 mm and 0.874 mm due to the internal cracks, (2) the thermally modified wood at 180°C by 2.5 hours has a decreased from 0,177 mm in thickness and the absences of internal cracks.

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O objetivo deste estudo é obter um modelo matemático logístico que representa a vaporização de toras de Eucalyptus grandis, em função do diâmetro e do tempo de permanência das toras no tratamento térmico a vapor. Para tanto, foram coletadas toras nas classes diamétricas de 25 a 40 cm de três árvores de E. grandis provenientes do Horto Florestal de Mandurí, SP. Em cada uma das toras foram inseridos três termopares, com profundidades distintas, 1/3 do raio; 2/3 do raio e o terceiro, próximo ao seu centro. Posteriormente, as toras foram vaporizadas a 85ºC e 100% de umidade relativa, até que o último termopar atingisse uma temperatura de 80ºC. Um Datalogger CR10 registrou as temperaturas, no interior do material, durante o tratamento térmico. Conclui-se que o modelo matemático logístico foi bem ajustado, obtido no tratamento térmico com vapor, levando em consideração as três classes de diâmetro e a profundidade máxima de 50 mm de raio, o modelo gerado, apresenta-se uma viabilidade técnica na aplicação do processo de aquecimento de toras com vapor, promovendo um consumo ideal de energia.