6,645 research outputs found

    Future techniques for tracking of synchronous satellites

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    A tracking system error analysis computer program is reported to study the feasibility of using range sum and range-rate sum measurements through a synchronous satellite to a user satellite, and range sum and range-rate sum measurements through a synchronous satellite to a ground based transponder for tracking of synchronous satellites. Error analysis transformed noise, bias, ground station location and orbit uncertainties into expected uncertainties in each of the orbits after tracking. Results show that both of the proposed measurement methods are feasible for determining and refining the orbits of future synchronous satellites

    A study of the blistering of metal surfaces by solar system ions First quarterly progress report, period ending 14 Jul. 1965

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    Pure aluminum single crystals irradiated in vacuum to define optimum parameters for oxide film removal with no residual blistering of surfac

    On the feasibility of radiation sterilization of planetary spacecraft Final report

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    Feasibility study for X-ray or gamma ray sterilization of spacecraft - radiation effect

    Varying-Parameter Supply Functions and the Sources of Economic Distress in American Agriculture, 1866-1914

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    The agrarian unrest in the United States at the end of the nineteenth century is examined. This unrest is often viewed as stemming from the inability of farmers to adapt to changing conditions in world agriculture. This hypothesis is tested in the context of a distributed lag supply function. Varying parameter estimation methods are used to trace the history of the parameters in the supply function and to decompose observed prices into permanent and transitory components over time. The patterns of variation are tested for conformity with a model of rational price-expectation formation. The conclusion is that farmers behaved as economic theory would predict, but that neither theory nor practice gave them relief from the troubles which plagued them.

    Nonlinear techniques for forecasting solar activity directly from its time series

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    This paper presents numerical techniques for constructing nonlinear predictive models to forecast solar flux directly from its time series. This approach makes it possible to extract dynamical in variants of our system without reference to any underlying solar physics. We consider the dynamical evolution of solar activity in a reconstructed phase space that captures the attractor (strange), give a procedure for constructing a predictor of future solar activity, and discuss extraction of dynamical invariants such as Lyapunov exponents and attractor dimension

    Handbook of space environmental effects on solar cell power systems

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    Space environmental effects on solar cell power systems for earth satellite

    Role of internal gases and creep of Ag in controlling the critical current density of Ag-sheathed Bi2Sr2CaCu2Ox wires

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    High engineering critical current density JE of >500 A/mm2 at 20 T and 4.2 K can be regularly achieved in Ag-sheathed multifilamentary Bi2Sr2CaCu2Ox (Bi-2212) round wire when the sample length is several centimeters. However, JE(20 T) in Bi-2212 wires of several meters length, as well as longer pieces wound in coils, rarely exceeds 200 A/mm2. Moreover, long-length wires often exhibit signs of Bi-2212 leakage after melt processing that are rarely found in short, open-end samples. We studied the length dependence of JE of state-of-the-art powder-in-tube (PIT) Bi-2212 wires and gases released by them during melt processing using mass spectroscopy, confirming that JE degradation with length is due to wire swelling produced by high internal gas pressures at elevated temperatures [1,2]. We further modeled the gas transport in Bi-2212 wires and examined the wire expansion at critical stages of the melt processing of as-drawn PIT wires and the wires that received a degassing treatment or a cold-densification treatment before melt processing. These investigations showed that internal gas pressure in long-length wires drives creep of the Ag sheath during the heat treatment, causing wire to expand, lowering the density of Bi-2212 filaments, and therefore degrading the wire JE; the creep rupture of silver sheath naturally leads to the leakage of Bi-2212 liquid. Our work shows that proper control of such creep is the key to preventing Bi-2212 leakage and achieving high JE in long-length Bi-2212 conductors and coils

    Effects of Enamel Paint on the Behavior and Survival of the Periodical Cicada, \u3ci\u3eMagicicada Septendecim\u3c/i\u3e (Homoptera) and the Lesser Migratory Grasshopper, \u3ci\u3eMelanoplus Sanguinipes (Orthoptera).

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    We present information compiled from several studies on the effects of methods for marking individual arthropods on their longevity and behavior. Results from our own research on effects of enamel paint marking on two in- sect species, the periodical cicada, Magicicada septendecim, and the lesser migratory grasshopper, Melanoplus sanguinipes, are also presented. Neither species showed any adverse survivorship or behavioral effects from marking
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