3,101 research outputs found

    Multiple jet study data correlations

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    Correlations are presented which allow determination of penetration and mixing of multiple cold air jets injected normal to a ducted subsonic heated primary air stream. Correlations were obtained over jet-to-primary stream momentum flux ratios of 6 to 60 for locations from 1 to 30 jet diameters downstream of the injection plane. The range of geometric and operating variables makes the correlations relevant to gas turbine combustors. Correlations were obtained for the mixing efficiency between jets and primary stream using an energy exchange parameter. Also jet centerplane velocity and temperature trajectories were correlated and centerplane dimensionless temperature distributions defined. An assumption of a Gaussian vertical temperature distribution at all stations is shown to result in a reasonable temperature field model. Data are presented which allow comparison of predicted and measured values over the range of conditions specified above

    Conceptual design and analysis of orbital cryogenic liquid storage and supply systems

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    A wide variety of orbital cryogenic liquid storage and supply systems are defined in NASA and DOD long-range plans. These systems include small cooling applications, large chemical and electrical orbit transfer vehicles and supply tankers. All have the common requirements of low-g fluid management to accomplish gas-free liquid expulsion and efficient thermal control to manage heat leak and tank pressure. A preliminary design study was performed to evaluate tanks ranging from 0.6 to 37.4 cu m (22 to 1320 cu ft). Liquids of interest were hydrogen, oxygen, methane, argon and helium. Conceptual designs were generated for each tank system and fluid dynamic, thermal and structural analyses were performed for Shuttle compatible operations. Design trades considered the paradox of conservative support structure and minimum thermal input. Orbital performance and weight data were developed, and a technology evaluation was completed

    Technical Note: Evaluation of a Crucible Furnace Retort for Laboratory Torrefactions of Wood Chips

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    Torrefaction is a thermal process that improves biomass performance as a fuel by property enhancements such as decreased moisture uptake and increased carbon density. Most studies to date have used very small amounts of finely ground biomass. This study reports the testing of a crucible furnace retort that was fabricated to produce intermediate quantities of torrefied material and to allow processing of wood chips. Yields ranging from 51 to 96% were impacted to a greater extent by differences in temperature than time of treatment. Although temperature-control issues (gradients, slow heating) were experienced with the crucible furnace retort, this equipment proved to be useful for its intended purpose

    Real Springer fibers and odd arc algebras

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    We give a topological description of the two-row Springer fiber over the real numbers. We show its cohomology ring coincides with the oddification of the cohomology ring of the complex Springer fiber introduced by Lauda-Russell. We also realize Ozsv\'ath-Rasmussen-Szab\'o odd TQFT from pullbacks and exceptional pushforwards along inclusion and projection maps between hypertori. Using these results, we construct the odd arc algebra as a convolution algebra over components of the real Springer fiber, giving an odd analogue of a construction of Stroppel-Webster

    V2:Performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz

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    The performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz with a maximum peak energy of 10 MJ is described. The solid deuterium converter with a volume of V=160 cm3 (8 mol), which is exposed to a thermal neutron fluence of 4.5x10^13 n/cm2, delivers up to 550 000 UCN per pulse outside of the biological shield at the experimental area. UCN densities of ~ 10/cm3 are obtained in stainless steel bottles of V ~ 10 L resulting in a storage efficiency of ~20%. The measured UCN yields compare well with the predictions from a Monte Carlo simulation developed to model the source and to optimize its performance for the upcoming upgrade of the TRIGA Mainz into a user facility for UCN physics.Comment: 23 pages, 8 figure

    New Hampshire Volunteer Beach Profile Monitoring Program (VBPMP): Implementation, Field Methods, and Data Processing

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    The New Hampshire (NH) Volunteer Beach Profiling Monitoring Program (VBPMP) monitors beach elevation profiles at multiple stations along the NH Atlantic coast on a near-monthly basis using the Emery method. The program grew from three monitoring stations in 2016-2017 to thirteen stations across six beaches in 2018, with an additional station added in 2022. The overarching goal of the VBPMP is to assess the stability of New Hampshire’s Atlantic beaches over multiple years to determine seasonal changes and long-term trends using citizen science methods. Included in the assessment of beach stability are erosional or accretional trends, response to storms, and comparisons between beaches with differing morphology, sediments, and infrastructure (e.g., seawalls or dunes). Presented in this report are the methods used by the NH VBPMP for establishing profile stations, collecting beach elevation profiles based on the Emery method, recording, and uploading field data, and taking field photographs. The methods used for processing profile data after collection by volunteers is also described, including data review and quality assurance, datum corrections, plotting elevation profiles, sediment volume computation, and determination of mean profile elevations. Finally, examples of data products created for sharing with the public are presented

    Passive Retention/Expulsion Methods for Subcritical Storage of Cryogens

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    Development of passive retention/expulsion system for subcritical storage of cryogenic material during low gravity situation

    Impacto ambiental da cultura do arroz irrigado com uso de índice de qualidade de água (IQA).

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    O presente trabalho tem por objetivo avaliar o possível impacto da cultura do arroz irrigado sobre a qualidade das águas do Rio Camboriú (Camboriú/SC), através do estabelecimento de um índice de qualidade de água.bitstream/CNPMA/5829/1/comunicado_08.pd
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