5,563 research outputs found

    Thermal fatigue and oxidation data on TAZ-8A, MAR-M 200, and Udimet 700 superalloys

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    The fluidized bed technique was used to determine the relative thermal fatigue and oxidation resistance of three superalloys: TAZ-8A, Mar-M 200, and Udimet 700. The alloys TAZ-8A and MAR-M 200 were also tested in the directionally-solidified form. For the 13 combinations of composition, solidification method, surface protection, and specimen geometry, the cycles to cracking varied from 1250 to 15,000. The alloy/coating having the best resistance to thermal fatigue cracking was coated directionally-solidified NASA TAZ-8A. This combination also had excellent oxidation resistance

    Loudness (annoyance), prediction procedure for steady sounds

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    Method has been devised to predict loudness level of any steady sound solely from its measured power spectrum level. Method is based on assumption that, with respect to loudness sensation, the human auditory system acts as open-loop transmission system with transmittance function determined from measured tone curves

    Analytical model for determining spacecraft impact velocity and orientation relative to an impact surface

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    Development of analytical model for determining spacecraft impact velocity and orientation relative to impact surface for variable dynamic condition

    Polarized Neutron Matter: A Lowest Order Constrained Variational Approach

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    In this paper, we calculate some of the polarized neutron matter properties, using the lowest order constrained variational method with the AV18AV_{18} potential and employing a microscopic point of view. A comparison is also made between our results and those of other many-body techniques.Comment: 23 pages, 8 figure

    Analysis of Magnetic Fields in Inertial Alfven Wave Collisions

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    Turbulence in astrophysical and space plasmas is dominated by the nonlinear interaction of counterpropagating Alfven waves. Most Alfven wave turbulence theories have been based on ideal plasma models, such as incompressible MHD, for Alfven waves at large scales. However, in the inertial Alfven wave regime (vA > vthe), relevant to magnetospheric plasmas, how the turbulent nonlinear interactions are modified by the dispersive nature of the waves remains to be explored. Here we present the first laboratory evidence of the nonlinear interaction in the inertial regime. A comparison is made with the theory for MHD Alfven waves.Comment: 2 pages, 1 figur

    Excitation Spectrum and Correlation Functions of the Z_3-Chiral Potts Quantum Spin Chain

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    We study the excitation spectrum and the correlation functions of the Z_3- chiral Potts model in the massive high-temperature phase using perturbation expansions and numerical diagonalization. We are mainly interested in results for general chiral angles but we consider also the superintegrable case. For the parameter values considered, we find that the band structure of the low- lying part of the excitation spectrum has the form expected from a quasiparticle picture with two fundamental particles. Studying the N-dependence of the spectrum, we confirm the stability of the second fundamental particle in a limited range of the momentum, even when its energy becomes so high that it lies very high up among the multiparticle scattering states. This is not a phenomenon restricted to the superintegrable line. Calculating a non-translationally invariant correlation function, we give evidence that it is oscillating. Within our numerical accuracy we find a relation between the oscillation length and the dip position of the momentum dispersion of the lightest particle which seems to be quite independent of the chiral angles.Comment: 19 pages + 6 PostScript figures (LaTeX); BONN-TH-94-2

    Concepts and procedures used to determine certain sea wave characteristics

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    A technique and its application are presented by which wave parameters, critical to spacecraft water impact load analysis, may be determined
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