10,291 research outputs found

    Zonal and tesseral harmonic coefficients for the geopotential function, from zero to 18th order

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    Zonal and tesseral harmonic coefficients for the geopotential function are usually tabulated in normalized form to provide immediate information as to the relative significance of the coefficients in the gravity model. The normalized form of the geopotential coefficients cannot be used for computational purposes unless the gravity model has been modified to receive them. This modification is usually not done because the absolute or unnormalized form of the coefficients can be obtained from the simple mathematical relationship that relates the two forms. This computation can be quite tedious for hand calculation, especially for the higher order terms, and can be costly in terms of storage and execution time for machine computation. In this report, zonal and tesseral harmonic coefficients for the geopotential function are tabulated in absolute or unnormalized form. The report is designed to be used as a ready reference for both hand and machine calculation to save the user time and effort

    Asymptotic solution of a model for bilayer organic diodes and solar cells

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    The current voltage characteristics of an organic semiconductor diode made by placing together two materials with dissimilar electron affinities and ionisation potentials is analysed using asymptotic methods. An intricate boundary layer structure is examined. We find that there are three regimes for the total current passing through the diode. For reverse bias and moderate forward bias the dependency of the voltage on the current is similar to the behaviour of conventional inorganic semiconductor diodes predicted by the Shockley equation and are governed by recombination at the interface of the materials. There is then a narrow range of currents where the behaviour undergoes a transition. Finally for large forward bias the behaviour is different with the current being linear in voltage and is primarily controlled by drift of charges in the organic layers. The size of the interfacial recombination rate is critical in determining the small range of current where there is rapid transition between the two main regimes. The extension of the theory to organic solar cells is discussed and the analogous current voltage curves derived in the regime of interest

    Evaluation of dry lubricants and bearings for spacecraft applications

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    Performance of dry film lubricated ball bearings in high vacuum environmen

    A comprehensive computer program for predicting solar cell performance

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    Comprehensive computer program for predicting solar cell performanc

    The Collapse of the Wien Tail in the Coldest Brown Dwarf? Hubble Space Telescope Near-Infrared Photometry of WISE J085510.83-071442.5

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    We present Hubble Space Telescope (HST) near-infrared photometry of the coldest known brown dwarf, WISE J085510.83-071442.5 (WISE 0855-0714). WISE 0855-0714 was observed with the Wide Field Camera 3 (WFC3) aboard HST using the F105W, F125W, and F160W filters, which approximate the YY, JJ, and HH near-infrared bands. WISE 0855-0714 is undetected at F105W with a corresponding 2σ\sigma magnitude limit of \sim26.9. We marginally detect WISE 0855-0714 in the F125W images (S/N \sim4), with a measured magnitude of 26.41 ±\pm 0.27, more than a magnitude fainter than the JJ-band magnitude reported by Faherty and coworkers. WISE J0855-0714 is clearly detected in the F160W band, with a magnitude of 23.90 ±\pm 0.02, the first secure detection of WISE 0855-0714 in the near-infrared. Based on these data, we find that WISE 0855-0714 has extremely red F105W-F125W and F125W-F160W colors relative to other known Y dwarfs. We find that when compared to the models of Saumon et al. and Morley et al., the F105W-F125W and F125W-F160W colors of WISE 0855-0714 cannot be accounted for simultaneously. These colors likely indicate that we are seeing the collapse of flux on the Wien tail for this extremely cold object.Comment: Accepted for publication in ApJ Letter

    Quantum critical behavior in disordered itinerant ferromagnets: Logarithmic corrections to scaling

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    The quantum critical behavior of disordered itinerant ferromagnets is determined exactly by solving a recently developed effective field theory. It is shown that there are logarithmic corrections to a previous calculation of the critical behavior, and that the exact critical behavior coincides with that found earlier for a phase transition of undetermined nature in disordered interacting electron systems. This confirms a previous suggestion that the unspecified transition should be identified with the ferromagnetic transition. The behavior of the conductivity, the tunneling density of states, and the phase and quasiparticle relaxation rates across the ferromagnetic transition is also calculated.Comment: 15pp., REVTeX, 8 eps figs, final version as publishe

    Anderson-Mott Transition in a Magnetic Field: Corrections to Scaling

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    It is shown that the Anderson-Mott metal-insulator transition of paramagnetic, interacting disordered electrons in an external magnetic field is in the same universality class as the transition from a ferromagnetic metal to a ferromagnetic insulator discussed recently. As a consequence, large corrections to scaling exist in the magnetic-field universality class, which have been neglected in previous theoretical descriptions. The nature and consequences of these corrections to scaling are discussed.Comment: 5pp., REVTeX, no figs, final version as publishe

    An exactly solvable toy model that mimics the mode coupling theory of supercooled liquid and glass transition

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    A toy model is proposed which incorporates the reversible mode coupling mechanism responsible for ergodic-nonergodic transition with trivial Hamiltonian in the mode coupling theory (MCT) of structural glass transition. The model can be analyzed without relying on uncontrolled approximations inevitable in the current MCT. The strength of hopping processes can be easily tuned and the ideal glass transition is reproduced only in a certain range of the strength. On the basis of the analyses of our model we discuss about a sharp ergodic-nonergodic transition and its smearing out by "hopping".Comment: 5 pages, 2 ps-figures, inappropriate terms replace

    Numerical study of a short-range p-spin glass model in three dimensions

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    In this work we study numerically a short range p-spin glass model in three dimensions. The behaviour of the model appears to be remarkably different from mean field predictions. In fact it shares some features typical of models with full replica-symmetry breaking (FRSB). Nevertheless, we believe that the transition that we study is intrinsically different from the FRSB and basically due to non-perturbative contributions. We study both the statics and the dynamics of the system which seem to confirm our conjectures.Comment: 20 pages, 15 figure
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