61 research outputs found

    Conceptual Design and Analysis of No-Insulation High-Temperature Superconductor Tubular Wave Energy Converter

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    So far, a number of wave energy converters (WEC) have been proposed to increase efficiency and economic feasibility. Particularly, tubular WEC with permanent magnets and coil winding packs is mostly used to convert the wave energy. Due to the demand for high magnetic flux density in WEC, research has been conducted on high-temperature superconductors (HTS) WEC. In this paper, the conceptual design of no-insulation (NI) HTS tubular WEC and its optimization process are proposed. Using NI technology, it has become possible to design WEC with high volumetric efficiency and cost-effectiveness. Furthermore, the design is analyzed in the aspect of electromagnetism, mechanical force, and cryogen. The performance of the proposed WEC is evaluated as a response to various waveforms and their amplitudes. A rectifying circuit of WEC connected in parallel with load resistance is used for the output power study

    Update on BDνB\to D^\ast \ell \nu form factor at zero-recoil using the Oktay-Kronfeld action

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    We present an update on the calculation of BˉDνˉ\bar{B}\to D^\ast \ell \bar{\nu} semileptonic form factor at zero recoil using the Oktay-Kronfeld bottom and charm quarks on Nf=2+1+1N_f=2+1+1 flavor HISQ ensembles generated by the MILC collaboration. Preliminary results are given for two ensembles with a0.12a\approx 0.12 and 0.090.09 fm and Mπ310M_\pi\approx 310 MeV. Calculations have been done with a number of valence quark masses, and the dependence of the form factor on them is investigated on the a0.12a\approx 0.12 fm ensemble. The excited state is controlled by using multistate fits to the three-point correlators measured at 4--6 source-sink separations.Comment: 7 pages and 4 figures. Talk at The 36th Annual International Symposium on Lattice Field Theory - LATTICE201

    Calculation of BSM Kaon B-parameters using Staggered Quarks

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    We present updated results for kaon B-parameters for operators arising in models of new physics. We use HYP-smeared staggered quarks on the Nf=2+1N_f = 2+1 MILC asqtad lattices. During the last year we have added new ensembles, which has necessitated chiral-continuum fitting with more elaborate fitting functions. We have also corrected an error in a two-loop anomalous dimension used to evolve results between different scales. Our results for the beyond-the-Standard-Model B-parameters have total errors of 5105-10\%. We find that the discrepancy observed last year between our results and those of the RBC/UKQCD and ETM collaborations for some of the B-parameters has been reduced from 4 ⁣ ⁣5σ4\!-\!5\,\sigma to 2 ⁣ ⁣3σ2\!-\!3\,\sigma.Comment: 7 pages, 8 figures, Lattice 2014 proceedin

    Denitrifying Bacteria Active in Woodchip Bioreactors at Low-Temperature Conditions

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    Woodchip bioreactor technology removes nitrate from agricultural subsurface drainage by using denitrifying microorganisms. Although woodchip bioreactors have demonstrated success in many field locations, low water temperature can significantly limit bioreactor efficiency and performance. To improve bioreactor performance, it is important to identify the microbes responsible for nitrate removal at low temperature conditions. Therefore, in this study, we identified and characterized denitrifiers active at low-temperature conditions by using culture-independent and -dependent approaches. By comparative 16S rRNA (gene) analysis and culture isolation technique, Pseudomonas spp., Polaromonas spp., and Cellulomonas spp. were identified as being important bacteria responsible for denitrification in woodchip bioreactor microcosms at relatively low temperature conditions (15°C). Genome analysis of Cellulomonas sp. strain WB94 confirmed the presence of nitrite reductase gene nirK. Transcription levels of this nirK were significantly higher in the denitrifying microcosms than in the non-denitrifying microcosms. Strain WB94 was also capable of degrading cellulose and other complex polysaccharides. Taken together, our results suggest that Cellulomonas sp. denitrifiers could degrade woodchips to provide carbon source and electron donors to themselves and other denitrifiers in woodchip bioreactors at low-temperature conditions. By inoculating these denitrifiers (i.e., bioaugmentation), it might be possible to increase the nitrate removal rate of woodchip bioreactors at low-temperature conditions
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