9,229 research outputs found

    Comparisons of wing pressure distribution from flight tests of flush and external orifices for Mach numbers from 0.50 to 0.97

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    Wing pressure distributions obtained in flight with flush orifice and external tubing orifice installations for Mach numbers from 0.50 to 0.97 are compared. The procedure used to install the external tubing orifice is discussed. The results indicate that external tubing orifice installations can give useful results

    Effect of an alternate winglet on the pressure and spanwise load distributions of a first generation jet transport wing

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    Pressure and spanwise load distributions on a first-generation jet transport semispan model at subsonic speeds are presented. The wind tunnel data were measured for the wing with and without an alternate winglet. The results show that the winglet affected outboard wing pressure distributions and increased the spanwise loads near the tip

    Effect of winglets on a first-generation jet transport wing. 1: Longitudinal aerodynamic characteristics of a semispan model at subsonic speeds

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    The effects of winglets and a simple wing-tip extension on the aerodynamic forces and moments and the flow-field cross flow velocity vectors behind the wing tip of a first generation jet transport wing were investigated in the Langley 8-foot transonic pressure tunnel using a semi-span model. The test was conducted at Mach numbers of 0.30, 0.70, 0.75, 0.78, and 0.80. At a Mach number of 0.30, the configurations were tested with combinations of leading- and trailing-edge flaps

    Effect of Winglets on a First-Generation Jet Transport Wing. 2: Pressure and Spanwise Load Distributions for a Semispan Model at High Subsonic Speeds

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    Pressure and spanwise load distributions on a first-generation jet transport semispan model at high subsonic speeds are presented for the basic wing and for configurations with an upper winglet only, upper and lower winglets, and a simple wing-tip extension. Selected data are discussed to show the general trends and effects of the various configurations

    Amazon River infl uence on nitrogen fi xation in the western tropical North Atlantic

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    We measured rates of N- and C-fixation with a direct tracer method in regions of the western tropical North Atlantic influenced by the Amazon River plume during the high flow period of 2010 (May–June 2010). We found distinct regional variations in N-fixation activity, with the lowest rates in the plume proper and the highest rates in the plume margins and in offshore waters. A comparison of our N- and C-fixation measurements showed that the relative contribution of N-fixation to total primary production increased from the plume core toward oceanic waters, and that most of the C-fixation in this system was supported by sources of nitrogen other than those derived from biological N-fixation, or diazotrophy. We complemented these rate experiments with measurements of the δ15N of suspended particles (δ15PN), which documented the important and often dominant role of diazotrophs in supplying nitrogen to particulate organic matter in the water column. These coupled measurements revealed that small phytoplankton contributed more new nitrogen to the particulate nitrogen pool than larger phytoplankton. We used a habitat classification method to assess the fac- tors that control diazotrophic activity and contribution to the suspended particle pool, both of which increased from the plume toward oceanic waters. Our findings provide an important constraint on the role of the Amazon plume in creating distinct niches and roles for diazotrophs in the nutrient and carbon budgets of the western tropical North Atlantic

    Evaluación de las condiciones de mezcla y su influencia sobre el cloro residual entanques de compensación de un sistema de distribución de agua potable

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    We performed a real scale evaluation of mixing conditions and its influence on water quality in a compensation tank of drinking-water distribution system located in the city of Cali, Colombia. The hydrodynamic study with continuous injection of tracer, and temperature and free chlorine measurements for identifying the mixing regime in the tank’s interior, residence time, thermal stratification, and chlorine variations in the stored water showed the typical characteristics of a compensation tank. We concluded that water recirculation, inadequate water exchange, low moment fluxes associated with low velocity flows, and punctual thermal stratification could lead to high water age, high residence times in the tank, inadequate mixing, and important loss of free residual chlorine. The methodology developed is suitable for evaluation and optimization of compensation tanks of drinking water distribution systems.Realizamos una evaluación a escala real de las condiciones de mezcla y su influencia en la calidad del agua en un tanque de compensación del sistema de distribución de agua potable ubicado en la ciudad de Cali, Colombia. El estudio hidrodinámico con inyección continua de marcador y mediciones de temperatura y cloro libre para identificar el régimen de mezcla en el interior del tanque, el tiempo de residencia, la estratificación térmica y las variaciones de cloro en el agua almacenada mostraron las características típicas de un tanque de compensación. Llegamos a la conclusión de que la recirculación de agua, el intercambio de agua inadecuado, los flujos de momento bajos asociados con los flujos de baja velocidad y la estratificación térmica puntual podrían conducir a una alta edad del agua, tiempos de residencia elevados en el tanque, mezcla inadecuada y pérdida importante de cloro residual libre. La metodología desarrollada es adecuada para la evaluación y optimización de tanques de compensación de sistemas de distribución de agua potable

    Effect of winglets on a first-generation jet transport wing. 3: Pressure and spanwise load distributions for a semispan model at Mach 0.30

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    Pressure and spanwise load distributions on a first-generation jet transport semispan model at a Mach number of 0.30 are given for the basic wing and for configurations with an upper winglet only, upper and lower winglets, and a simple wing-tip extension. To simulate second-segment-climb lift conditions, leading- and/or trailing-edge flaps were added to some configurations

    Implicancias ambientales de la deslignificación de pulpas kraft de eucalipto utilizando perácidos

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    Because of great environmental pressures, the cellulose industry has studied the potential of use of new bleaching agents among which peroxymonosulfuric acid and peracetic acid stand out. This survey summarizes the results of various laboratory investigations using peracids to delignify eucalyptus kraft pulps. The effect of a step using peroxymonosulfuric acid followed by a D-Eo-D sequence [free of elemental chlorine] was studied and compared with the use of peracetic acid and mixtures of these two acids. It was shown that a mixture of peroxymonosulfuric acid and peracetic acid reduced more lignin (measured as kappa index) than the individual peracids, and reduced more hexenuronic acid than peracetic acid with less degradation of the cellulose than with peroxymonosulfuric acid. This was explained on the basis of the electrophilic and nucleophilic properties of these acids that improved the delignification of eucalyptus kraft pulp. The effluents generated in these steps involving the peracids had greater color, chemical oxygen demand (COD), and total phenols correlating with the amount of lignin removed and the analyses of bioassays did not show acute toxicity from effluents coming from a peroxymonosulfuric acid step. The delignification with peracids may possibly reduce the use of chlorine dioxide in a sequence involving bleaching with elemental free chlorine (ECF), in this way reducing the concentration of organic chlorides (AOX) in the bleaching effluent

    Reproductive outcomes after hysteroscopic metroplasty for women with dysmorphic uterus and recurrent implantation failure

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    The aim of this study was to assess the reproductive outcomes of women with recurrent implantation failure (RIF) after hysteroscopic metroplasty for dysmorphic uteri. Methods: This retrospective observational study included 190 women with a diagnosis of RIF. These patients were eligible for hysteroscopic metroplasty for dysmorphic uteri, including T-shaped uteri, between January 2008 and September 2015 at the Instituto Valenciano de Infertilidad (IVI) in Valencia, Spain. Results: The total clinical pregnancy rate, the live birth rate, and the abortion rate were 80.0% (152/190), 77.9% (147/190) and 8.9%, respectively. At 12 months, the clinical pregnancy rate was 76.3% (145/190) and at 6 months 50.5% (96/190). After the metroplasty, approximately 76% of all gravidities, were achieved during the first 12 months of follow-up. Within the first IVF cycle, pregnancy and live birth rates were 77.8% and 86.1%, respectively. The mean time to pregnancy was 6.5 months. Conclusions: This study demonstrates that hysteroscopic metroplasty improves pregnancy and live birth rates for women with a history of recurrent implantation failure and dysmorphic uterus. However, conclusions must be taken carefully as this is an observational study. A prospective, randomized and controlled study is necessary to support these results
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