967 resultados para mesh, fluidodinamica, computazionele, STARDUST, ITER, simulazioni


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The main length at first maturity of anchovy Engraulis encrasicolus in Ghanaian waters has been estimated using length-frequency and gonad data sampled between June 1983 and September 1986 off Accra and Tema, Ghana. The length at first maturity of these fish is around 5.7 cm (fork length). The minimum mesh size for rational exploitation of the resource in Ghanaian waters is put at about 20 mm (0.8 inch).

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Metal-framed traps covered with polyethylene mesh used in the fishery for the South African Cape rock lobster (Jasus lalandii) incidentally capture large numbers of undersize (<75 mm CL) specimens. Air-exposure, handling, and release procedures affect captured rock lobsters and reduce the productivity of the stock, which is heavily fished. Optimally, traps should retain legalsize rock lobsters and allow sublegal animals to escape before traps are hauled. Escapement, based on lobster morphometric measurements, through meshes of 62 mm, 75 mm, and 100 mm was investigated theoretically under controlled conditions in an aquarium, and during field trials. SELECT models were used to model escapement, wherever appropriate. Size-selectivity curves based on the logistic model fitted the aquarium and field data better than asymmetrical Richards curves. The lobster length at 50% retention (L50) on the escapement curve for 100-mm mesh in the aquarium (75.5 mm CL) approximated the minimum legal size (75 mm CL); however estimates of L50 increased to 77.4 mm in field trials where trapentrances were sealed, and to 82.2 mm where trap-entrances were open. Therfore, rock lobsters that cannot escape through the mesh of sealed field traps do so through the trap entrance of open traps. By contrast, the wider selection range and lower L25 of field, compared to aquarium, trials (SR = 8.2 mm vs. 2.6 mm; L25 =73.4 mm vs. 74.1 mm), indicate that small lobsters that should be able to escape from 100-mm mesh traps do not always do so. Escapement from 62-mm mesh traps with open entrance funnels increased by 40−60% over sealed traps. The findings of this study with a known size distribution, are related to those of a recent indirect (comparative) study for the same species, and implications for trap surveys, commercial catch rates, and ghost fishing are discussed.

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Catch rates and sizes of blue crabs, Callinectes sapidus, were compared in traps with 2.54 cm (1.0 inch), 3.81 cm (1.5 inches), and 5.08 cm (2.0 inches) square mesh, 2.54 by 5.08 cm rectangular mesh, and 3.81 cm hexagonal mesh. Catch of legal blue crabs by number was significantly greater in the traditional hexagonal mesh trap than in all other trap types. Sublegal catch by number was highest (34.1-63.3% of total) in the 2.54 cm and 3.81 cm square mesh and rectangular mesh traps and lowest in the 5.08 cm square mesh trap. The hexagonal mesh trap had significantly lower catch rates of sublegal blue crabs than all other trap types except the 5.08 cm square mesh. Mean size of blue crabs by trap type exhibited an inverse pattern to that shown by catch of sublegal crabs. The most effective trap to maximize legal catch and minimize sublegal catch was the 3.81 cm hexagonal mesh trap followed by the 5.08 cm square mesh trap.

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Catch and mesh selectivity of wire-meshed fish traps were tested for eleven different mesh sizes ranging from 13 X 13 mm (0.5 x 0.5") to 76 x 152 mm (3 X 6"). A total of 1,810 fish (757 kg) representing 85 species and 28 families were captured during 330 trap hauls off southeastern Florida from December 1986 to July 1988. Mesh size significantly affected catches. The 1.5" hexagonal mesh caught the most fish by number, weight, and value. Catches tended to decline as meshes got smaller or larger. Individual fish size increased with larger meshes. Laboratory mesh retention experiments showed relationships between mesh shape and size and individual retention for snapper (Lutjanidae), grouper (Serranidae), jack (Carangidae), porgy (Sparidae), and surgeonfish (Acanthuridae). These relationships may be used to predict the effect of mesh sizes on catch rates. Because mesh size and shape greatly influenced catchability, regulating mesh size may provide a useful basis for managing the commercial trap fishery.

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O presente estudo se debruça sobre a experiência realizada no município de Duque de Caxias, localizado no estado do Rio de Janeiro, com o Programa Mais Educação, cujo objetivo é promover a educação em tempo integral. A educação é um elemento cultural que serve de instrumento para a mediação entre as relações humanas. Por sua característica transdisciplinar, tem se representado como um dos fatores principais para o desenvolvimento da sociedade no século XXI. A sociedade do conhecimento, com o incremento das tecnologias digitais da informação, depende do estímulo do poder público para incorporar esses novos elementos na educação, ainda carente de organização administrativa e econômica. A presente dissertação tem como objetivo discutir a importância da interferência do poder público para o desenvolvimento dos processos de ensino-aprendizagem, a partir da temática da Educação Integral. A educação em tempo integral desenvolve aspectos, no processo de aprendizagem, que projetam nos alunos, principalmente da educação infantil, uma nova dimensão cultural. A educação institucionalizada e associada ao Estado, como no caso da localidade analisada no presente estudo, pode contribuir em muito para o desenvolvimento social da comunidade. Entre os objetivos específicos da pesquisa, encontram-se a análise da política administrativa do município escolhido e a interpretação da estrutura normativa do direito à educação, evidenciando-se, neste percurso, o histórico de sua implementação. A justificativa do presente trabalho é explicitada pela necessidade de embasamento teórico e conceitual sobre o Direito à Educação apresentada pelas ações dos administrados públicos. Tal carência reflete-se na prática educativa e no cotidiano escolar de comunidades que, pela ausência de ações políticas eficazes, continuam a ser socialmente negligenciadas.