44,918 research outputs found

    Circuit minimizes current drain caused by neon indicator lamps

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    Circuit lights neon lamp by back leakage current of the driving transistor, rather than by the transistors saturation or ''on-state'' current, thereby eliminating lowering of the voltage necessary for indication. Circuit has operating speed greater than indication circuit using a saturation principle and aids in power rationing

    Variations in propagation delay times for line ten (TV) based time transfers

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    Variation in the propagation delay for a 30 km TV (Line Ten) radio link was evaluated for a series of 30 independent measurements. Time marks from TV Channel 5 WTTG in Washington, D.C. were simultaneously measured at the Johns Hopkins University Applied Physics Laboratory and at the United States Naval Observatory against each stations' local cesium standard clocks. Differences in the stations' cesium clocks were determined by portable cesium clock transfers. Thirty independent timing determinations were made. The root mean square deviation in the propagation delay calculated from the timing determinations was 11 ns. The variations seen in the propagation delays are believed to be caused by environmental factors and by errors in the portable clock timing measurements. In correlating the propagation delay variations with local weather conditions, only a moderate dependence on air temperature and absolute humidity was found

    Depositing spacing layers on magnetic film with liquid phase epitaxy

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    Liquid phase epitaxy spacing layer is compatible with systems which are hard-bubble proofed by use of second magnetic garnet film as capping layer. Composite is superior in that: circuit fabrication time is reduced; adherence is superior; visibility is better; and, good match of thermal expansion coefficients is provided

    Resolving discrete pulsar spin-down states with current and future instrumentation

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    An understanding of pulsar timing noise offers the potential to improve the timing precision of a large number of pulsars as well as facilitating our understanding of pulsar magnetospheres. For some sources, timing noise is attributable to a pulsar switching between two different spin-down rates (ν˙)(\dot{\nu}). Such transitions may be common but difficult to resolve using current techniques. In this work, we use simulations of ν˙\dot{\nu}-variable pulsars to investigate the likelihood of resolving individual ν˙\dot{\nu} transitions. We inject step-changes in the value of ν˙\dot{\nu} with a wide range of amplitudes and switching timescales. We then attempt to redetect these transitions using standard pulsar timing techniques. The pulse arrival-time precision and the observing cadence are varied. Limits on ν˙\dot{\nu} detectability based on the effects such transitions have on the timing residuals are derived. With the typical cadences and timing precision of current timing programs, we find we are insensitive to a large region of Δν˙\Delta \dot{\nu} parameter space which encompasses small, short timescale switches. We find, where the rotation and emission states are correlated, that using changes to the pulse shape to estimate ν˙\dot{\nu} transition epochs, can improve detectability in certain scenarios. The effects of cadence on Δν˙\Delta \dot{\nu} detectability are discussed and we make comparisons with a known population of intermittent and mode-switching pulsars. We conclude that for short timescale, small switches, cadence should not be compromised when new generations of ultra-sensitive radio telescopes are online.Comment: 19 pages, 11 figure

    HURDLE COUNT-DATA MODELS IN RECREATION DEMAND ANALYSIS

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    When a sample of recreators is drawn from the general population using a survey, many in the sample will not recreate at a recreation site of interest. This study focuses on nonparticipation in recreation demand modeling and the use of modified count-data models. We clarify the meaning of the single-hurdle Poisson (SHP) model and derive the double-hurdle Poisson (DHP) model. The latter is contrasted with the SHP and we show the DHP is consistent with Johnson and Kotz's zero-modified Poisson model.Resource /Energy Economics and Policy,

    PERCEIVED HAZARD AND PRODUCT CHOICE: AN APPLICATION TO RECREATIONAL SITE CHOICE

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    This study improves upon the standard "dummy variable" approach to modeling fish consumption advisories by jointly estimating a "perceived hazard" model and a site choice model. The perceived hazard model overcomes the shortcomings of the dummy variable model, namely that all anglers respond equally to advisories and that all anglers know of and believe the advisories. We find that anglers' perceived hazards associated with consumption advisories do affect product (recreational site) choice. Anglers' perceptions also affect welfare measures, where the benefits of contaminant removal follow a more reasonable pattern than that of the dummy variable approach. The joint perceived hazard/product choice model is applicable to a wide variety of risky choices with which consumers are faced.Resource /Energy Economics and Policy,

    Software for the grouped optimal aggregation technique

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    The grouped optimal aggregation technique produces minimum variance, unbiased estimates of acreage and production for countries, zones (states), or any designated collection of acreage strata. It uses yield predictions, historical acreage information, and direct acreage estimate from satellite data. The acreage strata are grouped in such a way that the ratio model over historical acreage provides a smaller variance than if the model were applied to each individual stratum. An optimal weighting matrix based on historical acreages, provides the link between incomplete direct acreage estimates and the total, current acreage estimate

    OPTION WEALTH AND BEQUEST VALUES: THE VALUE OF PROTECTING FUTURE GENERATIONS FROM THE HEALTH RISKS OF NUCLEAR WASTE STORAGE

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    We devise a simple model of intergenerational altruism under uncertainty. We present an estimable form of the model that relies on a few, plausible, assumptions. We apply the model to data collected in a survey of Southern Nevadans concerning the proposed Yucca Mountain Nuclear Waste Repository in Nye County, NV. We find strong evidence of a bequest motive. Approximately one third of the option wealth lost by households near the repository can be attributed to costs to future generations.Resource /Energy Economics and Policy,

    AGRICULTURAL AND RECREATIONAL IMPACTS FROM SURFACE FLOW CHANGES DUE TO GOLD MINING OPERATIONS

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    Nevada ranks third in the world in gold production. In order to operate the massive open pit gold mines, the State of Nevada granted mining companies a temporary permit to pump groundwater from near the open pits and dispose of it. Certain instream flows have nearly doubled relative to average historical flows in recent years. Following pit closure, surface flows will likely decline from historical levels. This study measures the impacts of these changing water supplies on downstream agricultural and recreational users. We argue that the creation of temporary changes in water rights for the downstream users would likely mitigate future losses both groups are expected to experience.Resource /Energy Economics and Policy,
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