11,256 research outputs found

    Viewfinder/tracking system for Skylab

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    Basic component of system is infrared spectrometer designed for manual target acquisition, pointing and tracking, and data-take initiation. System incorporates three main subsystems which include: (1) viewfinder telescope, (2) control panel and electronics assembly, and (3) IR-spectrometer case assembly

    Chaos and Turbulent Nucleosynthesis Prior to a Supernova Explosion

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    Three-dimensional (3D), time dependent numerical simulations, of flow of matter in stars, now have sufficient resolution to be fully turbulent. The late stages of the evolution of massive stars, leading up to core collapse to a neutron star (or black hole), and often to supernova explosion and nucleosynthesis, are strongly convective because of vigorous neutrino cooling and nuclear heating. Unlike models based on current stellar evolutionary practice, these simulations show a chaotic dynamics characteristic of highly turbulent flow. Theoretical analysis of this flow, both in the Reynolds-averaged Navier-Stokes (RANS) framework and by simple dynamic models, show an encouraging consistency with the numerical results. It may now be possible to develop physically realistic and robust procedures for convection and mixing which (unlike 3D numerical simulation) may be applied throughout the long life times of stars. In addition, a new picture of the presupernova stages is emerging which is more dynamic and interesting (i.e., predictive of new and newly observed phenomena) than our previous one.Comment: 11 pages, 2 figures, Submitted to AIP Advances: Stardust, added figures and modest rewritin

    Dihadron Fragmentation Functions in the NJL-jet model

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    The NJL-jet model provides a framework for calculating fragmentation functions without introducing ad hoc parameters. Here the NJL-jet model is extended to investigate dihadron fragmentation functions.Comment: 4 pages, 5 figures, Proceedings of 8th Circum-Pan-Pacific Symposium on High Energy Spin Physic
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