8,358 research outputs found

    General Electric 20-ampere hour nickel-cadmium battery

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    The interaction, effect, and controllability of the performance parameters of the General Electric 20-ampere-hour, 24-cell nickel cadmium battery are investigated. The battery was cycled under simulated orbit conditions. The acquired data was analyzed and evaluated in terms of battery parameters and performance characteristics. Conclusions and tests results are presented along with recommendations for further study

    Approach to Equilibrium for a Forced Burgers Equation

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    We show that approach to equilibrium in certain forced Burgers equations is implied by a decay estimate on a suitable intrinsic semigroup estimate, and we verify this estimate in a variety of cases including a periodic force.Comment: To appear in Journal of Evolution Equation

    Nickel-cadium batteries for Apollo telescope mount

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    The operational testing and evaluation program is presented which was conducted on 20-ampere-hour nickel-cadmium (Ni-Cd) batteries for use on the Apollo telescope mount (ATM). The test program was initiated in 1967 to determine if the batteries could meet ATM mission requirements and to determine operating characteristics and methods. The ATM system power and charging power for the Ni-Cd secondary batteries is provided by a solar array during the 58-minute daylight portion of the orbit; during the 36-minute night portion of the orbit, the Ni-Cd secondary batteries will supply ATM system power. The test results reflect battery operating characteristics and parameters relative to simulated ATM orbital test conditions. Maximum voltage, charge requirements, capacity, temperature, and cyclic characteristics are presented

    Transport in the random Kronig-Penney model

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    The Kronig-Penney model with random Dirac potentials on the lattice \ZM has critical energies at which the Lyapunov exponent vanishes and the density of states has a van Hove singularity. This leads to a non-trivial quantum diffusion even though the spectrum is known to be pure-point

    Positivity of Lyapunov exponents for a continuous matrix-valued Anderson model

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    We study a continuous matrix-valued Anderson-type model. Both leading Lyapunov exponents of this model are proved to be positive and distinct for all ernergies in (2,+)(2,+\infty) except those in a discrete set, which leads to absence of absolutely continuous spectrum in (2,+)(2,+\infty). This result is an improvement of a previous result with Stolz. The methods, based upon a result by Breuillard and Gelander on dense subgroups in semisimple Lie groups, and a criterion by Goldsheid and Margulis, allow for singular Bernoulli distributions

    On a class of random Schrödinger operators

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    AbstractConsidered are random Schrödinger operators on L2(Rd) that are stationary and metrically transitive with respect to a lattice e.g., H = H0 + Vω with Vω(x) = Σiϵzdqi(ω)ƒ(x − xi), {qi} independent identically distributed. A method of carrying over results from the case of potentials metrically transitive with respect to Rd is presented. Among these results are the Thouless formula and Kotani's theory

    Experimental investigation and model development of the Skylab ATM secondary nickel-cadmium batteries

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    The performance of a Ni-Cd battery was evaluated and the cyclic battery controls to be used on the ATM batteries were determined. Cell and battery performance models were developed which to predict the performance of the secondary Ni-Cd batteries on the ATM. Capacity degradation and charge acceptance characteristics were considered. Mathematical models for each of these operating areas were developed based on data from two separate test programs. The capacity degradation model describes the expected usable battery capacity as a function of time, temperature, and depth-of-discharge. The charge acceptance model describes the cell charge acceptance as a function of charge rate, temperature, and state of charge. The models were designed for computer use and to facilitate possible battery modification. They can be used to predict expected performance or to compare real time performance during flight

    Lifshitz Tails in Constant Magnetic Fields

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    We consider the 2D Landau Hamiltonian HH perturbed by a random alloy-type potential, and investigate the Lifshitz tails, i.e. the asymptotic behavior of the corresponding integrated density of states (IDS) near the edges in the spectrum of HH. If a given edge coincides with a Landau level, we obtain different asymptotic formulae for power-like, exponential sub-Gaussian, and super-Gaussian decay of the one-site potential. If the edge is away from the Landau levels, we impose a rational-flux assumption on the magnetic field, consider compactly supported one-site potentials, and formulate a theorem which is analogous to a result obtained in the case of a vanishing magnetic field

    Lifshitz tails for alloy type models in a constant magnetic field

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    In this note, we study Lifshitz tails for a 2D Landau Hamiltonian perturbed by a random alloy-type potential constructed with single site potentials decaying at least at a Gaussian speed. We prove that, if the Landau level stays preserved as a band edge for the perturbed Hamiltonian, at the Landau levels, the integrated density of states has a Lifshitz behavior of the type elog2E2bqe^{-\log^2|E-2bq|}
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