6,100 research outputs found

    The dynamic behavior of rotor entry vehicle configurations. Volume 2 - Digital computer program manual

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    Digital computer program for evaluating aerodynamic performance of rotor in flight in proximity to reentry capsul

    Driving the Environmental Justice Movement Forward: The Need for a Paternalistic Approach

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    The oxidation and sublimation of graphite in simulated re-entry environments

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    Graphite oxidation and sublimation in simulated reentry environment

    On neutron number dependence of B(E1;0+ --> 1-) reduced transition probability

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    A neutron number dependence of the E1 0+ --> 1- reduced transition probability in spherical even--even nuclei is analysed within the Q--phonon approach in the fermionic space to describe the structure of collective states. Microscopic calculations of the E1 0+ --> 1- transition matrix elements are carried out for the Xe isotopes based on the RPA for the ground state wave function. A satisfactory description of the experimental data is obtained.Comment: 8 pages, 4 figure

    Relativistic Jets and Long-Duration Gamma-ray Bursts from the Birth of Magnetars

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    We present time-dependent axisymmetric magnetohydrodynamic simulations of the interaction of a relativistic magnetized wind produced by a proto-magnetar with a surrounding stellar envelope, in the first 10\sim 10 seconds after core collapse. We inject a super-magnetosonic wind with E˙=1051\dot E = 10^{51} ergs s1^{-1} into a cavity created by an outgoing supernova shock. A strong toroidal magnetic field builds up in the bubble of plasma and magnetic field that is at first inertially confined by the progenitor star. This drives a jet out along the polar axis of the star, even though the star and the magnetar wind are each spherically symmetric. The jet has the properties needed to produce a long-duration gamma-ray burst (GRB). At 5\sim 5 s after core bounce, the jet has escaped the host star and the Lorentz factor of the material in the jet at large radii 1011\sim 10^{11} cm is similar to that in the magnetar wind near the source. Most of the spindown power of the central magnetar escapes via the relativistic jet. There are fluctuations in the Lorentz factor and energy flux in the jet on 0.010.1\sim 0.01-0.1 second timescale. These may contribute to variability in GRB emission (e.g., via internal shocks).Comment: 5 pages, 3 figures, accepted in MNRAS letter, presented at the conference "Astrophysics of Compact Objects", 1-7 July, Huangshan, Chin

    El medio ambiente urbano en Quito

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    Algorithm based comparison between the integral method and harmonic analysis of the timing jitter of diode-based and solid-state pulsed laser sources

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    AbstractA comparison between two methods of timing jitter calculation is presented. The integral method utilizes spectral area of the single side-band (SSB) phase noise spectrum to calculate root mean square (rms) timing jitter. In contrast the harmonic analysis exploits the uppermost noise power in high harmonics to retrieve timing fluctuation. The results obtained show that a consistent timing jitter of 1.2ps is found by the integral method and harmonic analysis in gain-switched laser diodes with an external cavity scheme. A comparison of the two approaches in noise measurement of a diode-pumped Yb:KY(WO4)2 passively mode-locked laser is also shown in which both techniques give 2ps rms timing jitter
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