24,940 research outputs found

    Spaceborne scanner imaging system errors

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    The individual sensor system design elements which are the priori components in the registration and rectification process, and the potential impact of error budgets on multitemporal registration and side-lap registration are analyzed. The properties of scanner, MLA, and SAR imaging systems are reviewed. Each sensor displays internal distortion properties which to varying degrees make it difficult to generate on orthophoto projection of the data acceptable for multiple pass registration or meeting national map accuracy standards and is also affected to varying degrees by relief displacements in moderate to hilly terrain. Nonsensor related distortions, associated with the accuracy of ephemeris determination and platform stability, have a major impact on local geometric distortions. Platform stability improvements expected from the new multi mission spacecraft series and improved ephemeris and ground control point determination from the NAVSTAR/global positioning satellite systems are reviewed

    Bulk Viscosity of Interacting Hadrons

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    We show that first approximations to the bulk viscosity ηv\eta_v are expressible in terms of factors that depend on the sound speed vsv_s, the enthalpy, and the interaction (elastic and inelastic) cross section. The explicit dependence of ηv\eta_v on the factor (13vs2)(\frac 13 - v_s^2) is demonstrated in the Chapman-Enskog approximation as well as the variational and relaxation time approaches. The interesting feature of bulk viscosity is that the dominant contributions at a given temperature arise from particles which are neither extremely nonrelativistic nor extremely relativistic. Numerical results for a model binary mixture are reported.Comment: 4 pages, 1 figure, Contribution to Quark Matter 2009, Knoxville, Tennessee, US

    Current status of models of Jupiter's magnetosphere in the light of Pioneer data

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    The salient features of the various models of Jupiter's magnetosphere are compared with each other and with the major findings of Pioneer 10 and 11. No single model explains all the major phenomena detected by the Pioneers. A unified model of Jupiter's magnetosphere is proposed

    The SST Fully-Synchronous Multi-GHz Analog Waveform Recorder with Nyquist-Rate Bandwidth and Flexible Trigger Capabilities

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    The design and performance of a fully-synchronous multi-GHz analog transient waveform recorder I.C. ("SST") with fast and flexible trigger capabilities is presented. The SST's objective is to provide multi-GHz sample rates with intrinsically-stable timing, Nyquist-rate sampling and high trigger bandwidth, wide dynamic range and simple operation. Containing 4 channels of 256 samples per channel, the SST is fabricated in an inexpensive 0.25 micrometer CMOS process and uses a high-performance package that is 8 mm on a side. It has a 1.9V input range on a 2.5V supply, exceeds 12 bits of dynamic range, and uses ~128 mW while operating at 2 G-samples/s and full trigger rates. With a standard 50 Ohm input source, the SST exceeds ~1.5 GHz -3 dB bandwidth. The SST's internal sample clocks are generated synchronously via a shift register driven by an external LVDS oscillator running at half the sample rate (e.g., a 1 GHz oscillator yields 2 G-samples/s). Because of its purely-digital synchronous nature, the SST has ps-level timing uniformity that is independent of sample frequencies spanning over 6 orders of magnitude: from under 2 kHz to over 2 GHz. Only three active control lines are necessary for operation: Reset, Start/Stop and Read-Clock. When operating as common-stop device, the time of the stop, modulo 256 relative to the start, is read out along with the sampled signal values. Each of the four channels integrates dual-threshold trigger circuitry with windowed coincidence features. Channels can discriminate signals with ~1mV RMS resolution at >600 MHz bandwidth.Comment: 3 pages, 6 figures, 1 table, submitted for publication in the Conference Record of the 2014 IEEE Nuclear Science Symposium, Seattle, WA, November 201

    Comparison of a model of Jupiter's magnetosphere with Pioneer data

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    A model of Jupiter's magnetosphere in which there is a circum-Jovian outflow of plasma from an inner corotating magnetodisc is compared with the observations of the Pioneer flybys
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