99,923 research outputs found

    Correction of the definition of mass-flow parameter in dynamic inflow modelling

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    Averages of shifted convolutions of d3(n)d_3(n)

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    We investigate the first and second moments of shifted convolutions of the generalised divisor function d3(n)d_3(n).Comment: 22 page

    Iterative Solutions for Low Lying Excited States of a Class of Schroedinger Equation

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    The convergent iterative procedure for solving the groundstate Schroedinger equation is extended to derive the excitation energy and the wave function of the low-lying excited states. The method is applied to the one-dimensional quartic potential problem. The results show that the iterative solution converges rapidly when the coupling gg is not too small.Comment: 14 pages, 4 figure

    Microscopic study of induced fission dynamics of 226^{226}Th with covariant energy density functionals

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    Static and dynamic aspects of the fission process of 226^{226}Th are analyzed in a self-consistent framework based on relativistic energy density functionals. Constrained relativistic mean-field (RMF) calculations in the collective space of axially symmetric quadrupole and octupole deformations, based on the energy density functional PC-PK1 and a δ\delta-force pairing, are performed to determine the potential energy surface of the fissioning nucleus, the scission line, the single-nucleon wave functions, energies and occupation probabilities, as functions of deformation parameters. Induced fission dynamics is described using the time-dependent generator coordinate method in the Gaussian overlap approximation. A collective Schr\"odinger equation, determined entirely by the microscopic single-nucleon degrees of freedom, propagates adiabatically in time the initial wave packet built by boosting the ground-state solution of the collective Hamiltonian for 226^{226}Th. The position of the scission line and the microscopic input for the collective Hamiltonian are analyzed as functions of the strength of the pairing interaction. The effect of static pairing correlations on the pre-neutron emission charge yields and total kinetic energy of fission fragments is examined in comparison with available data, and the distribution of fission fragments is analyzed for different values of the initial excitation energy.Comment: 25 pages, 14 figures, accepted for publication in Phys. Rev.

    Tracers of chromospheric structure. I. CaII H&\&K emission distribution of 13000 F, G and K stars in SDSS DR7 spectroscopic sample

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    We present chromospheric activity index SHKS\rm_{HK} measurements for over 13,000 F, G and K disk stars with high signal-to-noise ratio (>> 60) spectra in the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) spectroscopic sample. A parameter δ\deltaS is defined as the difference between SHKS\rm_{HK} and a `zero' emission line fitted by several of the most inactive stars. The SHKS\rm_{HK} indices of subgiant stars tend to be much lower than dwarfs, which provide a way to distinguish dwarfs and giants with relatively low resolution spectra. Cooler stars are generally more active and display a larger scatter than hotter stars. Stars associated with the thick disk are in general less active than those of the thin disk. The fraction of K dwarfs that are active drops with vertical distance from the Galactic plane. Metallicity affects SHKS\rm_{HK} measurements differently among F, G and K dwarfs in this sample. Using the open clusters NGC 2420, M67 and NGC6791 as calibrations, ages of most field stars in this SDSS sample range from 3-8 Gyr.Comment: 9 pages, 11 figures, AJ, 2013, 145, 14
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