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AR Young

Publications and source records attributed to AR Young.

9 recordsLinked to original sources

Novel techniques for characterizing complex water use patterns within a network based statistical hydrological model

Information on the magnitude and variability of flow regimes at the river reach scale is a central component of most aspects of water resource and water quality management. Within the UK, river stretches with permanent gauging stations represent less than one percent of the total number of river stretches mapped at a scale of 1:50,000 and fewer than 20% of gauged catchments can be regarded as having natural flow regimes. This paper is the second of two papers that describe the development and application of hydrological models for estimating the variability and magnitude of natural and artificially influenced flow regimes at ungauged sites. The development of the models for estimating statistical descriptions of both the natural and artificially influenced flow regimes at ungauged river reaches is described by Young et al. (Young AR, Gustard A, Bullock A, Sekulin AE, Croker KM. Sci Total Environ 2000: this issue). This paper describes a pragmatic approach for applying the model to a complex river basin and characterizing the impacts of water use in the basin through example. The basin selected for the application contains the Aire and the Calder catchments within south Yorkshire.

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A river network based hydrological model for predicting natural and influenced flow statistics at ungauged sites: Micro LOW FLOWS

Information on the magnitude and variability of flow regimes at the river reach scale is a central component of most aspects of water resource and water quality management. Within the UK the number of river reaches that are gauged represent less than 1% of the total number of river stretches mapped at a scale of 1:50,000. The paper is the first of two papers that describe the development and application of procedures within Micro LOW FLOWS for estimating the variability and magnitude of flow regimes at ungauged sites as represented by flow duration and mean flow statistics. This paper describes the development of the models whilst Young et al. (this volume) describes a pragmatic approach for applying the model to a river basin with complex water use patterns.

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High-gain wide-band gyrotron traveling wave amplifier with a helically corrugated waveguide

First bandwidth measurements of a novel gyrotron amplifier are presented. The coupling between the second harmonic cyclotron mode of a gyrating electron beam and the radiation field occurred in the region of near infinite phase velocity over a broad bandwidth by using a cylindrical waveguide with a helical corrugation on its internal surface. With a beam energy of 185 keV, the amplifier achieved a maximum output power of 1.1 MW, saturated gain of 37 dB, linear gain of 47 dB, saturated bandwidth of 8.4 to 10.4 GHz ( 21% relative bandwidth), and an efficiency of 29%, in good agreement with theory.

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Slow spin relaxation of Rb atoms confined in glass cells filled with dense 4He gas at 1.85 K

At temperatures below 2.1 K, long-lived gaseous Rb atoms in glass cells have been generated with a simple method: irradiating the cells, containing 4He gas and Rb metal, with a cw laser. The obtained atomic Rb density ( approximately 10(8) cm(-3)) decreases with a 1/e time constant of about 10 s at 1.85 K. We have performed optical pumping of the Rb atoms and measured the longitudinal electronic spin relaxation time at 1.85 K as well. For processes (such as Rb-He collisions) which do not remove the atomic Rb from the vapor, this relaxation time is found to be about 60+/-15 s.

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