951 resultados para Flame spread
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Cover title.
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Literature cited: p. 59-60.
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On verso: Alice Hamilton in front row, fourth from left.
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Mode of access: Internet.
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Includes bibliographical references.
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Mode of access: Internet.
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Mode of access: Internet.
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O objetivo deste trabalho é avaliar os fatores que afetam a determinação dos spreads nas operações de Certificado de Recebível do Agronegócio (CRA). Foram selecionadas na amostra todas as emissões registradas na ANBIMA entre os anos de 2012 e maio de 2016. Verificou-se que a remuneração desse título é influenciada principalmente pela presença de reforço de crédito/garantias, pelo setor originador dos recebíveis e pela companhia securitizadora. Em uma segunda análise mais detalhada e acrescentando as variáveis uma a uma de forma a testar a aderência do modelo, encontraram-se evidências de que o tamanho da emissão e o percentual de subordinação são importantes variáveis de controle na determinação do spread. Ao incluirmos a variável rating, esta passa a ser relevante e da mesma forma acontece com a garantia, demonstrando que o percentual de subordinação reduz o spread do título, mas quando se acrescenta garantia, ele deixa de ser significativo. O sinal da variável garantia é positivo e demonstra que se há a necessidade de incluir garantias na emissão, é porque provavelmente é essencial para que a emissão ocorra. Por fim, a variável securitizadora mostrou-se relevante, indicando que o investidor leva em consideração a qualidade da mesma para a precificação do título.
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Delayed spread-F occurrence as recorded by ionograms, following geomagnetic activity (GA) has been investigated using data from 88 stations located around the world. The spread-F occurrence is delayed progressively from one to three days, from subauroral to midlatitude regions. The equatorial latitudes show suppressed activity. An examination of daily spread-F occurrence values relative to the AE index reveals not only a main delay of one day, but also delays of two and three days. These delays involve principally GA occurring around 0600 hrs LT.
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Epidemics of marine pathogens can spread at extremely rapid rates. For example, herpes virus spread through pilchard populations in Australia at a rate in excess of 10 000 km year(-1), and morbillivirus infections in seals and dolphins have spread at more than 3000 km year(-1). In terrestrial environments, only the epidemics of myxomatosis and calicivirus in Australian rabbits and West Nile Virus in birds in North America have rates of spread in excess of 1000 km year(-1). The rapid rates of spread of these epidemics has been attributed to flying insect vectors, but flying vectors have not been proposed for any marine pathogen. The most likely explanation for the relatively rapid spread of marine pathogens is the lack of barriers to dispersal in some parts of the ocean, and the potential for long-term survival of pathogens outside the host. These findings caution that pathogens may pose a particularly severe problem in the ocean. There is a need to develop epidemic models capable of generating these high rates of spread and obtain more estimates of disease spread rate.
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The development of near-resonant holographic interferometry techniques for use on flows seeded with atomic species is described. A theoretical model for the refractivity that is due to the seed species is outlined, and an approximation to this model is also described that is shown to be valid for practical regimes of interest and allows the number density of the species to be determined without knowledge of line-broadening effects. The details of quantitative number density experiments performed on an air-acetylene flame are given, and a comparison with an alternative absorption-based experiment is made. (C) 2004 Optical Society of America.