82,223 research outputs found

    Lyapunov Instability for a hard-disk fluid in equilibrium and nonequilibrium thermostated by deterministic scattering

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    We compute the full Lyapunov spectra for a hard-disk fluid under temperature gradient and shear. The system is thermalized by deterministic and time-reversible scattering at the boundary. This thermostating mechanism allows for energy fluctuations around a mean value which is reflected by only two vanishing Lyapunov exponents in equilibrium and nonequilibrium. The Lyapunov exponents are calculated with a recently developed formalism for systems with elastic hard collisions. In a nonequilibrium steady state the average phase space volume is contracted onto a fractal attractor leading to a negative sum of Lyapunov exponents. Since the system is driven inhomogeneously we do not expect the conjugate pairing rule to hold which is confirmed numerically.Comment: 13 pages (revtex) with 8 figures (encapsulated postscript

    Rotating raster generator

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    A rotating raster generator is provided which enables display of a television raster at any arbitrary roll angle. The generator includes four integrator circuits each of which receives a first voltage input corresponding to the sine or cosine of the desired roll angle and a second input comprising conventional horizontal or vertical sync pulses. The integrator circuits each comprise an operational amplifier and a capacitor connected for producing a ramp output having a rate of change proportional to the roll angle input, an electronic switch responsive to the sync input for resetting the integrator, and a summer that adds the ramp output of the integrator to the roll angle input so as to provide a zero-centered deflection control voltage

    Secondary cadmium-air batteries

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    Sponge cadmium electrodes for secondary cadmium-air batterie

    Effect of resonance-oblateness coupling on a satellite orbit

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    Second order effects of the coupling between geopotential resonance and oblateness on a satellite orbit are calculated. Results show that: (1) these effects arise from the interaction of resonance with the secular changes of the orbit's node, perigee, and mean anomaly; (2) they have the same period and phase as first order resonance perturbations; and (3) their amplitudes are proportional to the square of the period and dominate the first order effects as the orbit becomes commensurate. A striking example of this coupling is seen in the 18 day resonance variation of the node of the orbit of the first earth resources technology satellite. Analysis of this one arc second (31m) variation yielded a strong 14th order constraint to the geopotential for odd degree terms. This constraint is poorly predicted by current models

    The restricted problem of three bodies /3/ Final report

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    Variations of limiting asymptotic orbits with mass ratio for restricted three body proble

    Secondary iron-air batteries

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    Self discharge, capacity maintenance, oxidation, and water loss problems in secondary iron-air batterie

    The geopotential at synchronous-orbit altitudes

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    The earth's gravity potential at synchronous orbit satellite altitudes is studied by analyzing the small effects of the resonant harmonic of gravity in tracking data from eight satellites during 21 distinct drift-free arcs. Results show: (1) absolute accuracy of second degree resonant geopotential coefficients better than three percent and coefficients through fourth degree better than 15 percent; (2) positions of equilibrium points for geostationary satellites better than 1/2 degree; and (3) accuracy in predicting orbits for 24-hour satellites better than 1 degree for periods greater than 2 years

    The geoid spectrum from altimetry

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    Satellite altimetry information from the world's major oceans was analyzed to arrive at a geoid power spectrum. Using the equivalent of about 7 revolutions of data (mostly from GEOS-3) the power spectrum of the sea surface generally follows the expected values from Kaula's rule applied to the geoid. Analysis of overlapping altimetry arcs (and oceanographic data) shows that the surface spectrum is dominated by the geoid to about 500 cycles (40 km half wavelength) but that sea state departures are significant starting at about 250 cycles (80 km). Estimates of geopotential variances from a derived (smooth) geoid spectrum show significantly less power than Kaula's rule to about 60 cycles, but somewhat more from there to about 400 cycles. At less than 40 km half wavelength, the total power in the marine geoid may be negligible

    The drift of an inclined-orbit 24-hour satellite in an earth gravity field through fourth order

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    Drift of inclined-orbit 24-hour satellite in earth gravity field through fourth orde
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