18,854 research outputs found

    Gravitational Radiation from a Spinning Ellipsoid of Uniform Density

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    Gravitational radiation calculation of spinning ellipsoid of uniform density for estimation of energy loss rate of collapsing neutron sta

    On the theory of polarization transfer in inhomogeneous magnetized plasmas

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    Polarization transfer theory in inhomogeneous magnetized plasmas with mode couplin

    Fourth Order Gradient Symplectic Integrator Methods for Solving the Time-Dependent Schr\"odinger Equation

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    We show that the method of splitting the operator eϵ(T+V){\rm e}^{\epsilon(T+V)} to fourth order with purely positive coefficients produces excellent algorithms for solving the time-dependent Schr\"odinger equation. These algorithms require knowing the potential and the gradient of the potential. One 4th order algorithm only requires four Fast Fourier Transformations per iteration. In a one dimensional scattering problem, the 4th order error coefficients of these new algorithms are roughly 500 times smaller than fourth order algorithms with negative coefficient, such as those based on the traditional Ruth-Forest symplectic integrator. These algorithms can produce converged results of conventional second or fourth order algorithms using time steps 5 to 10 times as large. Iterating these positive coefficient algorithms to 6th order also produced better converged algorithms than iterating the Ruth-Forest algorithm to 6th order or using Yoshida's 6th order algorithm A directly.Comment: 11 pages, 2 figures, submitted to J. Chem. Phy

    Calculation of symmetric and asymmetric vortex seperation on cones and tangent ogives based on discrete vortex models

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    An inviscid discrete vortex model, with newly derived expressions for the tangential velocity imposed at the separation points, is used to investigate the symmetric and asymmetric vortex separation on cones and tangent ogives. The circumferential locations of separation are taken from experimental data. Based on a slender body theory, the resulting simultaneous nonlinear algebraic equations in a cross-flow plane are solved with Broyden's modified Newton-Raphson method. Total force coefficients are obtained through momentum principle with new expressions for nonconical flow. It is shown through the method of function deflation that multiple solutions exist at large enough angles of attack, even with symmetric separation points. These additional solutions are asymmetric in vortex separation and produce side force coefficients which agree well with data for cones and tangent ogives

    A review on tribological behaviour of polymeric composites and future reinforcements

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    Many different families of polymers are used in industries and engineering applications. The demands for studying the tribological behaviour of polymers and their composites are recently increased. This article briefs the most recent studies on the tribological behaviour of polymeric materials based on synthetic fibres. It reviews several factors which control the wear and frictional characteristics of such materials, that is, additives, fibres, interfacial adhesion, tribology environment, operating parameters, and composite geometry. In addition to that, new bioreinforcement (fibre) is introduced associated with preliminary results. The results showed that there is high potential of replacing the conventional reinforcement with the bioones

    GEODYN system description, volume 1

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    A computer program for the estimation of orbit and geodetic parameters is presented. The areas in which the program is operational are defined. The specific uses of the program are given as: (1) determination of definitive orbits, (2) tracking instrument calibration, (3) satellite operational predictions, and (4) geodetic parameter estimation. The relationship between the various elements in the solution of the orbit and geodetic parameter estimation problem is analyzed. The solution of the problems corresponds to the orbit generation mode in the first case and to the data reduction mode in the second case

    NEUROLEPTIC MALIGNANT SYNDROME: A CASE REPORT

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    The neuroleptic malignant syndrome is a rare but potentially fatal complication of neuroleptic administration. Many clinicians may not be familiar with this complication. This case'report highlights the clinical features of neuroleptic malignant syndrome and its management. CASE HISTOR
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