49,072 research outputs found

    Alternatives to formic acid as a grass silage additive under two contrasting ensilability conditions

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    peer-reviewedThe effects of formic acid and four alternative additives on silage fermentation, in-silo DM losses and aerobic stability were compared in an experiment using both difficultto- ensile (DIFF) and easier-to-ensile (EASI) herbages. Both were ensiled in laboratory silos with either no additive or following the application of formic acid (FA; 850 g/kg) at 3 mL/kg herbage, Add-SaFeR® (ATF1) and GrasAAT® (ATF2), both based on ammonium tetraformate, at 4 mL/kg herbage, an antimicrobial mixture (MIX; potassium formate, sodium disulfite and sodium benzoate) at 3 g/kg herbage, or Ecosyl (LAB; Lactobacillus plantarum) at 3 mL/kg herbage. There were four replicates per treatment and the silos were stored for 132 days. DIFF silage made without additive was poorly fermented. All additives increased the extent and improved the direction of DIFF silage fermentation, and reduced in-silo losses. However, MIX did not reduce butyric acid concentration and increased the extent of aerobic deterioration. LAB had a smaller effect on fermentation and in-silo losses than FA. With EASI silages, all additives restricted the extent of fermentation and improved fermentation quality, with the latter effect being smaller than for DIFF silages. LAB promoted a particularly homolactic fermentation but subsequently increased aerobic deterioration. In both DIFF and EASI silages additive treatment improved in vitro digestibility. It is concluded that only ATF1, ATF2 and MIX were as effective as FA at improving silage preservation and reducing in-silo losses with both DIFF and EASI herbages. However, ATF1 and ATF2 were superior in reducing the apparent extent of proteolysis and MIX was slightly less effective at reducing the activity of saccharolytic Clostridia

    Effects of percentage of blockage and flameholder downstream counterbores on lean combustion limits of premixed, prevaporized propane-air mixture

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    Lean combustion limits were determined for a premixed prevaporized propane air mixture with flat plate flame stabilizers. Experiments were conducted in a constant area flame tube combustor utilizing flameholders of varying percentages of blockage and downstream counterbores. Combustor inlet air velocity at ambient conditions was varied from 4 to 9 meters per second. Flameholders with a center hole and four half holes surrounding it were tested with 63, 73, and 85 percent blockage and counterbore diameters of 112 and 125 percent of the thru hole diameter, in addition to the no counterbore configuration. Improved stability was obtained by using counterbore flameholders and higher percentages of blockage. Increases in mixture velocity caused the equivalence ratio at blowout to increase in all cases

    Multiple path prediction for traffic scenes using LSTMs and mixture density models

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    This work presents an analysis of predicting multiple future paths of moving objects in traffic scenes by leveraging Long Short-Term Memory architectures (LSTMs) and Mixture Density Networks (MDNs) in a single-shot manner. Path prediction allows estimating the future positions of objects. This is useful in important applications such as security monitoring systems, Autonomous Driver Assistance Systems and assistive technologies. Normal approaches use observed positions (tracklets) of objects in video frames to predict their future paths as a sequence of position values. This can be treated as a time series. LSTMs have achieved good performance when dealing with time series. However, LSTMs have the limitation of only predicting a single path per tracklet. Path prediction is not a deterministic task and requires predicting with a level of uncertainty. Predicting multiple paths instead of a single one is therefore a more realistic manner of approaching this task. In this work, predicting a set of future paths with associated uncertainty was archived by combining LSTMs and MDNs. The evaluation was made on the KITTI and the CityFlow datasets on three type of objects, four prediction horizons and two different points of view (image coordinates and birds-eye vie

    Tetraquark bound states in a constituent quark model and the nature of the a_0(980) and f_0(980)

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    In this work we study tetraquark bound states in the framework of the constituent quark model of Ref. [2], which has been used for the description of non-strange two- and three-baryon systems and later on applied to the hadron spectra.Comment: Contribution to the MESON 2002 Workshop. Krakow 24-28 May 200

    Dual regimes of ion migration in high repetition rate femtosecond laser inscribed waveguides

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    Ion migration in high repetition rate femtosecond laser inscribed waveguides is currently being reported in different optical glasses. For the first time we discuss and experimentally demonstrate the presence of two regimes of ion migration found in laser written waveguides. Regime-I, corresponds to the initial waveguide formation mainly via light element migration (in our case atomic weight < 31u), whereas regime-II majorly corresponds to the movement of heavy elements. This behavior brings attention to a problem which has never been analyzed before and that affects laser written active waveguides in which active ions migrate changing their local spectroscopic properties. The migration of active ions may in fact detune the pre-designed optimal values of active photonic devices. This paper experimentally evidences this problem and provides solutions to avert it.Comment: 4 pages, 5 figure