24,844 research outputs found

    Design definition study of a lift/cruise fan technology V/STOL airplane: Summary

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    A two-engine three-fan V/STOL airplane was designed to fulfill naval operational requirements. A multimission airplane was developed from study of specific point designs. Based on the multimission concept, airplanes were designed to demonstrate and develop the technology and operational procedures for this class of aircraft. Use of interconnected variable pitch fans led to a good balance between high thrust with responsive control and efficient thrust at cruise speeds. The airplanes and their characteristics are presented

    Geometrical phase driven predissociation: Lifetimes of 2^2 A' levels of H_3

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    We discuss the role of the geometrical phase in predissociation dynamics of vibrational states near a conical intersection of two electronic potential surfaces of a D_{3h} molecule. For quantitative description of the predissociation driven by the coupling near a conical intersection, we developed a method for calculating lifetimes and positions of vibrational predissociated states (Feshbach resonances) for X_3 molecule. The method takes into account the two coupled three-body potential energy surfaces, which are degenerate at the intersection. As an example, we apply the method to obtain lifetimes and positions of resonances of predissociated vibrational levels of the 2^2 A' electronic state of the H_3 molecule. The three-body recombination rate coefficient for the H+H+H -> H_2+H process is estimated.Comment: 4 pages, 4 figure

    Walking on a fence: Brazil’s public-sector debt

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    Brazil is walking on a fence between sustainable and unsustainable public-debt dynamics. How it treads could affect not only its own economic prosperity but that of its neighbors, emerging markets in general, and U.S. financial institutions in particular. Relatively small improvements in Brazilian economic conditions and a continuation of that country’s recent fiscal improvements could push Brazil in the right direction, particularly if the dollar continues to depreciate.Debts, Public - Brazil ; Economic conditions - Brazil

    Wave packet dynamics of potassium dimers attached to helium nanodroplets

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    The dynamics of vibrational wave packets excited in K2_2 dimers attached to superfluid helium nanodroplets is investigated by means of femtosecond pump-probe spectroscopy. The employed resonant three-photon-ionization scheme is studied in a wide wavelength range and different pathways leading to K2+^+_2-formation are identified. While the wave packet dynamics of the electronic ground state is not influenced by the helium environment, perturbations of the electronically excited states are observed. The latter reveal a strong time dependence on the timescale 3-8 ps which directly reflects the dynamics of desorption of K2_2 off the helium droplets

    Exhaust jet wake and thrust characteristics of several nozzles designed for VTOL DOWNWASH suppression. Tests in and out of ground effect with 70 deg F and 1200 deg F nozzle discharge temperatures

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    Jet wake degradation and thrust characteristics of exhaust nozzles designed for VTOL downwash suppression and fuselage and ground effect

    Pseudohiponatrèmia

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    Effect of calf-starter protein solubility on calf performance

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    Three starters containing differently processed protein supplements were fed to Holstein heifer calves, using an early weaning program. One starter contained soybean meal. The other starters contained soybean grits processed through an extrusion cooker to reduce the protein solubility to an intermediate (PDI> 50%) or low (PDI < 15 %) level. Calf performance was similar on all three starters

    Fine Grain Photographic Development

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    The effect of different fine grain photographic developers upon the effective emulsion speed and grainines of photographic materials was studied quantitively. Fine grain developers were found to be more effective in reducing the graininess of fast coarse grain emulsions than of slow fine grain emulsions. The effective emulsion speed of slow fine grain emulsions when developed in a MQ Borax developer was found to be at least equal to that of a fast coarse grain emulsion when developed in an ultra fine grain developer which gave negatives of as low graininess on the fast emulsion as the .i\IQ Borax gave on the slow emulsion. Slight improvement in graininess can be obtained by using ultra fine grain developers on fine grain emulsions, but only at some sacrifice of effective emulsion speed
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