102,540 research outputs found

    An inviscid model of the solar wind

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    Inviscid, thermal conductive, spherically symmetric solar wind model - model solution by integration of mass, momentum, and energy conservation equation

    Resolving the wave-vector and the refractive index from the coefficient of reflectance

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    We resolve the existing controversy concerning the selection of the sign of the normal-to-the-interface component of the wave-vector kzk_z of an electromagnetic wave in an active (gain) medium. Our method exploits the fact that no ambiguity exists in the case of a {\em film} of the active medium since its coefficient of reflectance is invariant under the inversion of the sign of kzk_z. Then we show that the limit of the infinite film thickness determines a unique and physically consistent choice of the wave-vector and the refractive index. Practically important implications of the theory are identified and discussed.Comment: 6 pages, 4 figure

    SAR data compression: Application, requirements, and designs

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    The feasibility of reducing data volume and data rate is evaluated for the Earth Observing System (EOS) Synthetic Aperture Radar (SAR). All elements of data stream from the sensor downlink data stream to electronic delivery of browse data products are explored. The factors influencing design of a data compression system are analyzed, including the signal data characteristics, the image quality requirements, and the throughput requirements. The conclusion is that little or no reduction can be achieved in the raw signal data using traditional data compression techniques (e.g., vector quantization, adaptive discrete cosine transform) due to the induced phase errors in the output image. However, after image formation, a number of techniques are effective for data compression
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