5,044 research outputs found

    Adaptive data acquisition multiplexing system and method

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    A reconfigurable telemetry multiplexer is described which includes a monitor-terminal and a plurality of remote terminals. The remote terminals each include signal conditioning for a plurality of sensors for measuring parameters which are converted by an analog to digital converter. CPU's in the remote terminals store instructions for prompting system configuration and reconfiguration commands. The measurements, instructions, and the terminal's present configuration and status data are transmitted to the monitor-terminal and displayed. In response to menu-driven prompts generated and displayed at the monitor-terminal, data generation request commands, status and health commands, and the like are input at the monitor-terminal and transmitted to the remote terminals. The CPU in each remote terminal receives the various commands, stores them in electrically alterable memory, and reacts in accordance with the commands to reconfigure a plurality of aspects of the system. The CPU in each terminal also generates parameter measurements, status and health signals, and transmits these signals of the respective terminals to the monitor-terminal for low data rate operator viewing and to higher rate external transmission/monitor equipment. Reconfiguration may be in real time during the general period of parameter measurement acquisition, and may include alteration of the gain, automatic gain rescaling, bias, and or sampling rates associated with one or more of the parameter measurements made by the remote terminals

    An assessment of the efficacy of deep drains constructed in the wheatbelt of Western Australia Part 1 A discussion on drainage implmentation in the wheatbelt : a case study review, summary, conclusions and recommendations

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    Australia has undertaken a strategic review of current and historical deep drainage projects. A \u27rapid appraisal\u27 methodology was utilised, based principally on existing hydrological investigations and interpretation and anecdotal evidence provided by landholders to clarify the role of drainage in managing water in dry land rural landscapes. The objectives of this discussion paper are to: 1. Review the current status of groundwater drainage practice 2. Provide an assessment of deep drains in the landscape and 3. Propose recommendations on the development of drainage policy to enable the application of best management practice in groundwater drainage.https://researchlibrary.agric.wa.gov.au/bulletins/1012/thumbnail.jp

    CHANG-ES V: Nuclear Radio Outflow in a Virgo Cluster Spiral after a Tidal Disruption Event

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    We have observed the Virgo Cluster spiral galaxy, NGC~4845, at 1.6 and 6 GHz using the Karl G. Jansky Very Large Array, as part of the `Continuum Halos in Nearby Galaxies -- an EVLA Survey' (CHANG-ES). The source consists of a bright unresolved core with a surrounding weak central disk (1.8 kpc diameter). The core is variable over the 6 month time scale of the CHANG-ES data and has increased by a factor of ≈\approx 6 since 1995. The wide bandwidths of CHANG-ES have allowed us to determine the spectral evolution of this core which peaks {\it between} 1.6 and 6 GHz (it is a GigaHertz-peaked spectrum source).We show that the spectral turnover is dominated by synchrotron self-absorption and that the spectral evolution can be explained by adiabatic expansion (outflow), likely in the form of a jet or cone. The CHANG-ES observations serendipitously overlap in time with the hard X-ray light curve obtained by Nikolajuk \& Walter (2013) which they interpret as due to a tidal disruption event (TDE) of a super-Jupiter mass object around a 105 M⊙10^5\, M_\odot black hole. We outline a standard jet model, provide an explanation for the observed circular polarization, and quantitatively suggest a link between the peak radio and peak X-ray emission via inverse Compton upscattering of the photons emitted by the relativistic electrons. We predict that it should be possible to resolve a young radio jet via VLBI as a result of this nearby TDE.Comment: 45 pages, 10 figures, accepted July 2, 2015 to the Astrophysical Journa

    Corn cutworm control for 1983

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    "This guide recommends management practices and insecticides for reduction of injury caused by the various cutworms attacking com in Missouri. It also discusses the life cycles of the more common species which feed at and below ground and those species which are primarily above ground foliage feeders."--First page.George W. Thomas, Armon J. Keasler, Richard N. Story and Judy A. Grundler (Department of Entomology, College of Agriculture)Revised 2/83/8

    Detecting the stochastic gravitational wave background using pulsar timing

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    The direct detection of gravitational waves is a major goal of current astrophysics. We provide details of a new method for detecting a stochastic background of gravitational waves using pulsar timing data. Our results show that regular timing observations of 40 pulsars each with a timing accuracy of 100 nano-seconds will be able to make a direct detection of the predicted stochastic background from coalescing black holes within five years. With an improved pre-whitening algorithm, or if the background is at the upper end of the predicted range, a significant detection should be possible with only 20 pulsars.Comment: Accepted by ApJ Letter

    Mapping High-velocity H-alpha and Lyman-alpha Emission from Supernova 1987A

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    We present new {\it Hubble Space Telescope} images of high-velocity H-α\alpha and Lyman-α\alpha emission in the outer debris of SN~1987A. The H-α\alpha images are dominated by emission from hydrogen atoms crossing the reverse shock. For the first time we observe emission from the reverse shock surface well above and below the equatorial ring, suggesting a bipolar or conical structure perpendicular to the ring plane. Using the Hα\alpha imaging, we measure the mass flux of hydrogen atoms crossing the reverse shock front, in the velocity intervals (−-7,500~<<~VobsV_{obs}~<<~−-2,800 km s−1^{-1}) and (1,000~<<~VobsV_{obs}~<<~7,500 km s−1^{-1}), MH˙\dot{M_{H}} = 1.2~×\times~10−3^{-3} M⊙_{\odot} yr−1^{-1}. We also present the first Lyman-α\alpha imaging of the whole remnant and new ChandraChandra X-ray observations. Comparing the spatial distribution of the Lyman-α\alpha and X-ray emission, we observe that the majority of the high-velocity Lyman-α\alpha emission originates interior to the equatorial ring. The observed Lyman-α\alpha/H-α\alpha photon ratio, ⟨\langleR(Lα/Hα)R(L\alpha / H\alpha)⟩\rangle ≈\approx~17, is significantly higher than the theoretically predicted ratio of ≈\approx 5 for neutral atoms crossing the reverse shock front. We attribute this excess to Lyman-α\alpha emission produced by X-ray heating of the outer debris. The spatial orientation of the Lyman-α\alpha and X-ray emission suggests that X-ray heating of the outer debris is the dominant Lyman-α\alpha production mechanism in SN 1987A at this phase in its evolution.Comment: 6 pages, 5 figures. ApJL - accepte
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