28,975 research outputs found

    A study of optimum cowl shapes and flow port locations for minimum drag with effective engine cooling, volume 2

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    The listings, user's instructions, sample inputs, and sample outputs of two computer programs which are especially useful in obtaining an approximate solution of the viscous flow over an arbitrary nonlifting three dimensional body are provided. The first program performs a potential flow solution by a well known panel method and readjusts this initial solution to account for the effects of the boundary layer displacement thickness, a nonuniform but unidirectional onset flow field, and the presence of air intakes and exhausts. The second program is effectually a geometry package which allows the user to change or refine the shape of a body to satisfy particular needs without a significant amount of human intervention. An effort to reduce the cruise drag of light aircraft through an analytical study of the contributions to the drag arising from the engine cowl shape and the foward fuselage area and also that resulting from the cooling air mass flowing through intake and exhaust sites on the nacelle is presented. The programs may be effectively used to determine the appropriate body modifications or flow port locations to reduce the cruise drag as well as to provide sufficient air flow for cooling the engine

    Partition-dependent framing effects in lab and field prediction markets

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    Many psychology experiments show that individually judged probabilities of the same event can vary depending on the partition of the state space (a framing effect called "partition-dependence"). We show that these biases transfer to competitive prediction markets in which multiple informed traders are provided economic incentives to bet on their beliefs about events. We report results of a short controlled lab study, a longer field experiment (betting on the NBA playoffs and the FIFA World Cup), and naturally-occurring trading in macro-economic derivatives. The combined evidence suggests that partition-dependence can exist and persist in lab and field prediction markets

    Automated design of minimum drag light aircraft fuselages and nacelles

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    The constrained minimization algorithm of Vanderplaats is applied to the problem of designing minimum drag faired bodies such as fuselages and nacelles. Body drag is computed by a variation of the Hess-Smith code. This variation includes a boundary layer computation. The encased payload provides arbitrary geometric constraints, specified a priori by the designer, below which the fairing cannot shrink. The optimization may include engine cooling air flows entering and exhausting through specific port locations on the body

    Symmetry breaking in MAST plasma turbulence due to toroidal flow shear

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    The flow shear associated with the differential toroidal rotation of tokamak plasmas breaks an underlying symmetry of the turbulent fluctuations imposed by the up-down symmetry of the magnetic equilibrium. Using experimental Beam-Emission-Spectroscopy (BES) measurements and gyrokinetic simulations, this symmetry breaking in ion-scale turbulence in MAST is shown to manifest itself as a tilt of the spatial correlation function and a finite skew in the distribution of the fluctuating density field. The tilt is a statistical expression of the "shearing" of the turbulent structures by the mean flow. The skewness of the distribution is related to the emergence of long-lived density structures in sheared, near-marginal plasma turbulence. The extent to which these effects are pronounced is argued (with the aid of the simulations) to depend on the distance from the nonlinear stability threshold. Away from the threshold, the symmetry is effectively restored

    The effects of isometric work on heart rate, blood pressure, and net oxygen cost

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    Isometric exercise effects on heart rate, blood pressure, and net oxygen cos

    Changes in Biomedical and Physical Correlates in Behavioral Weight Loss with Retarded Youths

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    Seventeen trainable mentally retarded youths were assigned to either a behavior therapy (N = 6), an obese wait·list control group (N = 5) or a normal weight control group (N = 6). The behavior therapy subjects lost significantly more weight than the two control groups who gained weight. The behavior therapy subjects achieved significant reductions in tricep skin· fold thickness, abdominal circumferences, and diastolic blood pressure measures by the end of the 21·week treatment program. The advantages of using multiple dependent measures is discussed

    Geologic and tectonic setting of the MARK area

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