156 research outputs found

    Efeito da assepsia na germinação de sementes de Caatingueira-verdadeira.

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    Objetivou-se com este trabalho avaliar a influência da assepsia na germinação de sementes de catingueira-verdadeira (poincianella pyramidalis (Tu!.) L.P. Queiroz).Edição dos Resumos do V Workshop de Tecnologia e Fisiologia de Sementes e Mudas, Petrolina, dez. 2014

    TRANSIENT HEAT TRANSFER ANALYSIS UP TO DRYOUT IN 3D FUEL RODS UNDER UNIDEAL CONDITIONS THROUGH THE DEVELOPMENT OF A COMPUTER CODE

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    In this paper we analyze a conjugated transient heat transfer problem consisting of a nuclear reactor’s fuel rod and its intrinsic coolant channel. Our analysis is made possible through a computer code being developed at the Instituto de Engenharia Nuclear (IEN/CNEN). This code is meant to study the temperature behavior in fuel rods which exhibit deviation from their ideal conditions, that is, rods in which the cladding is deformed or the fuel is dislocated. It is also designed to avoid the use of the computationally expensive Navier-Stokes equations. For these reasons, its physical model has as basis a three-dimensional fuel rod coupled to a one-dimensional coolant channel, which are discretized using the finite element method. Intending to study accidental conditions in which the coolant (light water) transcends its saturation temperature, turning into vapor, a homogeneous mixture is used to represent the two-phase flow, and so the coolant channel’s energy equation is described using enthalpy. Owing to the fact that temperature and enthalpy are used in the physical model, it became impractical to generate a fully coupled method for solving the pertinent equations. Thus, the conjugated heat transfer problem is solved in a segregated manner through the implementation of an iterative method. Finally, as study cases for this paper we present analyses concerning the behavior of the hottest fuel rod in a Pressurized Water Reactor during a shutdown wherein the residual heat removal system is lost (loss of the reactor’s coolant pumps). These studies contemplate cases in which the fuel rod’s geometry is ideal or curved. Analyses are also performed for two circumstances of positioning of the fuel inside the rod: concentric and eccentric.In this paper we analyze a conjugated transient heat transfer problem consisting of a nuclear reactor’s fuel rod and its intrinsic coolant channel. Our analysis is made possible through a computer code being developed at the Instituto de Engenharia Nuclear (IEN/CNEN). This code is meant to study the temperature behavior in fuel rods which exhibit deviation from their ideal conditions, that is, rods in which the cladding is deformed or the fuel is dislocated. It is also designed to avoid the use of the computationally expensive Navier-Stokes equations. For these reasons, its physical model has as basis a three-dimensional fuel rod coupled to a one-dimensional coolant channel, which are discretized using the finite element method. Intending to study accidental conditions in which the coolant (light water) transcends its saturation temperature, turning into vapor, a homogeneous mixture is used to represent the two-phase flow, and so the coolant channel’s energy equation is described using enthalpy. Owing to the fact that temperature and enthalpy are used in the physical model, it became impractical to generate a fully coupled method for solving the pertinent equations. Thus, the conjugated heat transfer problem is solved in a segregated manner through the implementation of an iterative method. Finally, as study cases for this paper we present analyses concerning the behavior of the hottest fuel rod in a Pressurized Water Reactor during a shutdown wherein the residual heat removal system is lost (loss of the reactor’s coolant pumps). These studies contemplate cases in which the fuel rod’s geometry is ideal or curved. Analyses are also performed for two circumstances of positioning of the fuel inside the rod: concentric and eccentric.In this paper we analyze a conjugated transient heat transfer problem consisting of a nuclear reactor’s fuel rod and its intrinsic coolant channel. Our analysis is made possible through a computer code being developed at the Instituto de Engenharia Nuclear (IEN/CNEN). This code is meant to study the temperature behavior in fuel rods which exhibit deviation from their ideal conditions, that is, rods in which the cladding is deformed or the fuel is dislocated. It is also designed to avoid the use of the computationally expensive Navier-Stokes equations. For these reasons, its physical model has as basis a three-dimensional fuel rod coupled to a one-dimensional coolant channel, which are discretized using the finite element method. Intending to study accidental conditions in which the coolant (light water) transcends its saturation temperature, turning into vapor, a homogeneous mixture is used to represent the two-phase flow, and so the coolant channel’s energy equation is described using enthalpy. Owing to the fact that temperature and enthalpy are used in the physical model, it became impractical to generate a fully coupled method for solving the pertinent equations. Thus, the conjugated heat transfer problem is solved in a segregated manner through the implementation of an iterative method. Finally, as study cases for this paper we present analyses concerning the behavior of the hottest fuel rod in a Pressurized Water Reactor during a shutdown wherein the residual heat removal system is lost (loss of the reactor’s coolant pumps). These studies contemplate cases in which the fuel rod’s geometry is ideal or curved. Analyses are also performed for two circumstances of positioning of the fuel inside the rod: concentric and eccentric

    Curva de embebição de sementes Enterolobium contortisiliquum (Vell) Morong (FABACEAE).

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    Objetivou-se com este trabalho avaliar o padrão de embebição das sementes Enterolobium contortisiliquum submetida a diferentes concentrações polietilenoglicol.Edição dos Resumos do V Workshop de Tecnologia e Fisiologia de Sementes e Mudas, Petrolina, dez. 2014

    Crescimento inicial de mudas de Aspidosperma pyrifolium irrigadas com água com diferentes níveis de salinidade.

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    O objetivo do trabalho foi avaliar o efeito da salinidade no crescimento inicial de mudas de Aspidosperma pyrifolium.Edição dos Resumos do V Workshop de Tecnologia e Fisiologia de Sementes e Mudas, Petrolina, dez. 2014

    Comparative study on hematological parameters of farmed matrinxã, Brycon amazonicus Spix and Agassiz, 1829 (Characidae: Bryconinae) with others Bryconinae species.

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    O objetivo deste estudo foi determinar os parâmetros eritrocíticos, as contagens de trombócitos e de leucócitos de espécimes de Brycon amazonicus (matrinxã), criados em cativeiro e compará-los com aqueles descritos na literatura para outras espécies de Bryconinae. Além disso, foi ainda investigada a presença de células granulocíticas especiais nestes peixes. Os resultados dos parâmetros sangüíneos apresentados para B. amazonicus podem ajudar a entender melhor as características sangüíneas em população natural desta espécie de grande importância para a aqüicultura brasileira. Os parâmetros sangüíneos das espécies de Bryconinae investigadas apresentaram variação interespecíficas principalmente a contagem de eritrócitos, hemoglobina, hematócrito e volume corpuscular médio (VCM). A presença dos granulócitos sangüíneos, neutrófilos e heterófilos em matrinxã sugere que esta pode ser uma característica das espécies pertencentes à subfamília Bryconinae. Além disso, indica que a existência de células granulocíticas especiais no sangue de espécies de Bryconinae da literatura é um artefato, e isto foi aqui discutido

    Efeito do armazenamento em diferentes ambientes e embalagens na germinação de sementes de Aroeira-do-Sertão.

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    Objetivou-se com este trabalho avaliar o comportamento fisiológico das sementes de aroeira-do-sertão (Myracrodruon urundeuva Allemão) armazenadas em diferentes embalagens e ambientes.Edição dos Resumos do V Workshop de Tecnologia e Fisiologia de Sementes e Mudas, Petrolina, dez. 2014

    Desenvolvimento de mudas de pereiro (Aspidosperma pyrifolium Mart.) irrigadas com água salobra e biossalina

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    Objetivou-se com este trabalho avaliar o desenvolvimento de mudas de Aspidosperma pyrifolium Mart. sob diferentes níveis de salinidade da irrigação.Edição dos Resumos do V Workshop de Tecnologia e Fisiologia de Sementes e Mudas, Petrolina, dez. 2014
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