10,315 research outputs found

    EVALUATION OF THE APPLICABILITY OF A TURBULENT WAKE INLET BOUNDARY CONDITION

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    With the objective of reducing the computational cost of the iterative processes of aerodynamic components design, tests were carried out to study under what conditions, and with what difference, only part of the calculation domain can be solved using as input information obtained from complete simulations already solved. An experimental study of an airfoil exposed to the wake interference of an upstream airfoil at a Reynolds number of 150,000 was used to verify the solutions of the Reynolds-Averaged Navier-Stokes equations solved applying the k-ω Shear Stress Transport model for turbulence closure. A Grid Convergence Index study was performed to verify if the solution of the equations for the adopted discretization leads to results within the asymptotic range. With the physical coherence of the numerical methodology verified, comparisons between the simulations with the domain comprising the two airfoils and the domain comprising only the downstream airfoil were performed. Computational time reductions in the order of 40% are observed. The differences in the aerodynamic coefficients for the two types of simulation are presented as a function of distances non-dimensionalized by the characteristic length of the body that disturbs the flow forming the wake, showing that the difference between the two methods was inversely proportional to the distance between the two bodies. Behavior that was maintained until a point where the simulation diverges, equivalent to 25% of the characteristic length of the body that generates the wake

    Hadrons in AdS/QCD models

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    We discuss applications of gauge/gravity duality to describe the spectrum of light hadrons. We compare two particular 5-dimensional approaches: a model with an infrared deformed Anti-de Sitter metric and another one based on a dynamical AdS/QCD framework with back-reacted geometry in a dilaton/gravity background. The models break softly the scale invariance in the infrared region and allow mass gap for the field excitations in the gravity description, while keeping the conformal property of the metric close to the four-dimensional boundary. The models provide linear Regge trajectories for light mesons, associated with specially designed infrared gravity properties. We also review the results for the decay widths of the f0's into two pions, as overlap integrals between mesonic string amplitudes, which are in qualitative agreement with data

    Classificação e seleção de matéria-prima: atividades vitais para alavancar a competitividade da cadeia produtiva da amêndoa de castanha de caju brasileira.

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    Apesar de a castanha de caju ter influência decisiva no resultado da cadeia produtiva da amêndoa de castanha de caju brasileira, os métodos de classificação e seleção utilizados atualmente não conseguem distinguir com precisão as suas diferenças qualitativas.bitstream/item/35389/1/Bd-014.pd

    Modelos de regressão para determinar a estabilização da variabilidade de dados de energia metabolizábel em aves.

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    O objetivo do presente foi demonstrar o uso do modelo de platô com resposta linear como ferramenta para a tomada de decisão em experimentos biológicos. Foram utilizados dados de um experimento conduzido na Embrapa Suínos e Aves Concórdia/SC, cujo objetivo era determinar o tempo mínimo de coleta total de excretas para determinação da energia metabolizável com pintos de corte. A avaliação dos dados foi baseada no coeficiente de variação (como medida de variabilidade) em função do tempo de coleta, ajustando-se um modelo de platô com resposta linear, de forma que em certo tempo de coleta ocorreria a estabilização da variabilidade dos dados. Esse modelo permitiu identificar e recomendar que quatro dias de coleta total de excretas já seriam suficientes para estabilizar o coeficiente de variação da energia metabolizável aparente

    Fatores condicionantes a eficiência técnica e econômica da cajucultura nordestina.

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    Com base em dados levantados pelo CNPCa/EMBRAPA, relativos a safra 1988/89, testou-se a hipotese de que a baixa eficiencia tecnica e economica da cajucultura nordestina esta condicionada a fatores economicos, sociais e agronomicos. No Estado do Ceara, constatou-se que, dentro as variaveis com maior influencia positiva sobre a eficiencia tecnica e economica, destacaram-se o valor da terra ou qualidade dos solos, mao-de-obra empregada, educacao e montante de credito de custeio. No piaui, as variaveis da maior importancia na explicacao da eficiencia tecnica e economica foram idade do plantio, numero de plantas por hectare, assistencia tecnica e mao-de-obra empregada.bitstream/item/33715/1/Bp-003.pd

    Recombinants from the crosses between amphidiploid and cultivated peanut (Arachis hypogaea) for pest-resistance breeding programs.

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    Peanut is a major oilseed crop worldwide. In the Brazilian peanut production, silvering thrips and red necked peanut worm are the most threatening pests. Resistant varieties are considered an alternative to pest control. Many wild diploid Arachis species have shown resistance to these pests, and these can be used in peanut breeding by obtaining hybrid of A and B genomes and subsequent polyploidization with colchicine, resulting in an AABB amphidiploid. This amphidiploid can be crossed with cultivated peanut (AABB) to provide genes of interest to the cultivar. In this study, the sterile diploid hybrids from A. magna V 13751 and A. kempff-mercadoi V 13250 were treated with colchicine for polyploidization, and the amphidiploids were crossed with A. hypogaea cv. IAC OL 4 to initiate the introgression of the wild genes into the cultivated peanut. The confirmation of the hybridity of the progenies was obtained by: (1) reproductive characterization through viability of pollen, (2) molecular characterization using microsatellite markers and (3) morphological characterization using 61 morphological traits with principal component analysis. The diploid hybrid individual was polyploidized, generating the amphidiploid An 13 (A. magna V 13751 x A. kempff-mercadoi V 13250)4x. Four F1 hybrid plants were obtained from IAC OL 4 × An 13, and 51 F2 seeds were obtained from these F1 plants. Using reproductive, molecular and morphological characterizations, it was possible to distinguish hybrid plants from selfed plants. In the cross between A. hypogaea and the amphidiploid, as the two parents are polyploid, the hybrid progeny and selves had the viability of the pollen grains as high as the parents. This fact turns the use of reproductive characteristics impossible for discriminating, in this case, the hybrid individuals from selfing. The hybrids between A. hypogaea and An 13 will be used in breeding programs seeking pest resistance, being subjected to successive backcrosses until recovering all traits of interest of A. hypogaea, keeping the pest resistance
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