1,916 research outputs found

    Research Notes: Evaluation of some soybean isolines in irrigation culture

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    About 9% of the total soybean acreage and about 50% of the total corn acreage in Nebraska was irrigated at least once during the growing season in 1975. The 1975 state averages for irrigated soybeans and irrigated corn were 2220 and 7605 kg/ha respectively. Obviously, this yield differential (in relation to the price and production cost differentials) accounts for the reason most farmers utilize their irrigated acreage for corn rather than soybeans

    A nanoflare model for active region radiance: application of artificial neural networks

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    Context. Nanoflares are small impulsive bursts of energy that blend with and possibly make up much of the solar background emission. Determining their frequency and energy input is central to understanding the heating of the solar corona. One method is to extrapolate the energy frequency distribution of larger individually observed flares to lower energies. Only if the power law exponent is greater than 2, is it considered possible that nanoflares contribute significantly to the energy input. Aims. Time sequences of ultraviolet line radiances observed in the corona of an active region are modelled with the aim of determining the power law exponent of the nanoflare energy distribution. Methods. A simple nanoflare model based on three key parameters (the flare rate, the flare duration time, and the power law exponent of the flare energy frequency distribution) is used to simulate emission line radiances from the ions Fe XIX, Ca XIII, and Si iii, observed by SUMER in the corona of an active region as it rotates around the east limb of the Sun. Light curve pattern recognition by an Artificial Neural Network (ANN) scheme is used to determine the values. Results. The power law exponents, alpha 2.8, 2.8, and 2.6 for Fe XIX, Ca XIII, and Si iii respectively. Conclusions. The light curve simulations imply a power law exponent greater than the critical value of 2 for all ion species. This implies that if the energy of flare-like events is extrapolated to low energies, nanoflares could provide a significant contribution to the heating of active region coronae.Comment: 4 pages, 5 figure

    Designing Contextualized Learning

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    Specht, M. (2008). Designing Contextualized Learning. In H. H. Adelsberger, Kinshuk, J. M. Pawlowski & D. Sampson (Eds.), Handbook on Information Technologies for Education and Training (2th ed., pp. 101-111). Springer, Berlin Heidelberg 2008: International Handbook on Information Systems Series.Contextualized and ubiquitous learning are relatively new research areas that combine the latest developments in ubiquitous and context aware computing with pedagogical approaches relevant to structure more situated and context aware learning support. Searching for different backgrounds of mobile and contextualized learning authors have identified the relations between existing educational paradigms and new classes of mobile appli- cations for education (Naismith, Lonsdale, Vavoula, & Sharples, 2004). Furthermore best practices of mobile learning applications have been iden- tified and discussed in focused workshops (Stone, Alsop, Briggs, & Tomp- sett, 2002; Tatar, Roschelle, Vahey, & Peunel, 2002). Especially in the area of educational field trips (Equator Project, 2003; RAFT, 2003) in the last years innovative approaches for intuitive usage of contextualized mo- bile interfaces have been developed. The following paper describes the motivation and background for con- textualizing learning and illustrates the implementation of a service based and flexible learning toolkit developed in the RAFT project for supporting contextualized collaborative learning support

    Superconducting MgB(2) films via precursor post-processing approach

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    Superconducting MgB(2) films with Tc = 38.6 K were prepared using a precursor-deposition, ex-situ post-processing approach. Precursor films of boron, ~0.5 micrometer thick, were deposited onto Al(2)O(3) (102) substrates by e-beam evaporation; a post-anneal at 890 deg C in the presence of bulk MgB(2) and Mg metal produced highly crystalline MgB(2) films. X-ray diffraction indicated that the films exhibit some degree of c-axis alignment, but are randomly oriented in-plane. Transport current measurements of the superconducting properties show high values of the critical current density and yield an irreversibility line that exceeds that determined by magnetic measurements on bulk polycrystalline materials.Comment: PDF file with 10 pages total, including 4 figure

    Heat transport through the active layer of the moving bed in rotary drums

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    The heat transfer at the freeboard surface of the solid bed was experimentally investigated in a batch rotary drum with a diameter of 0.6 m and a length of 0.45 m. The change of temperature at the surface and inside the bed was measured with Type-K thermocouples and an infrared camera. The thermocouples are specifically arranged at different radial distances from the inner wall. Experiments have been done with a variation of the operational conditions rotational speed from 1 to 6 rpm and filling degree from 5% to 15%. As test materials glass beads, quartz sand, steel spheres and expanded clay were used, whereas the impact of particle size and thermo-physical properties on the heat transport through free bed surface was analyzed. A characteristic effective thermal conductivity was defined for the active layer to represent the heat transport from the free bed surface.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

    Experimental investigation of thermal bed mixing in rotary drums

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    Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.The transversal solid bed mixing was experimentally conducted in a batch rotary drum with a diameter of 0.6 m and a length of 0.45 m. The drum was filled with two fractions of granular material with different thermal conditions. The mixing temperature in the solid bed was measured with thermocouples located at different bed height. The mixing behavior was investigated for various rotational speeds, filling degrees, materials and particle sizes.The current study has been funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) within the project SPP 1679 SCHE 322/11-1. The authors would like to acknowledge the generous support.am201

    Study of dimuon production in Indium-Indium collisions with the NA60 experiment

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    The NA60 experiment at the CERN-SPS is devoted to the study of dimuon production in heavy-ion and proton-nucleus collisions. We present preliminary results from the analysis of Indium-Indium collisions at 158 GeV per nucleon. The topics covered are low mass vector meson production, J/psi production and suppression, and the feasibility of the open charm measurement from the dimuon continuum in the mass range below the J/psi peak.Comment: Contribution at XXXXth Rencontres de Moriond, "QCD and High Energy Hadronic Interactions
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