11,699 research outputs found

    Measured noise of a scale model high speed propeller at simulated takeoff/approach conditions

    Get PDF
    A model high-speed advanced propeller, SR-7A, was tested in the NASA Lewis 9x15 foot anechoic wind tunnel at simulated takeoff/approach conditions of 0.2 Mach number. These tests were in support of the full-scale Propfan Text Assessment (PTA) flight program. Acoustic measurements were taken with fixed microphone arrays and with an axially translating microphone probe. Limited aerodynamic measurements were also taken to establish the propeller operating conditions. Tests were conducted with the propeller alone and with three down-stream wing configurations. The propeller was run over a range of blade setting angles from 32.0 deg. to 43.6 deg., tip speeds from 183 to 290 m/sec (600 to 950 ft/sec), and angles of attack from -10 deg. to +15 deg. The propeller alone BPF tone noise was found to increase 10 dB in the flyover plane at 15 deg. propeller axis angle of attack. The installation of the straight wing at minimum spacing of 0.54 wing chord increased the tone noise 5 dB under the wing of 10 deg. propeller axis angle of attack, while a similarly spaced inboard upswept wing only increased the tone noise 2 dB

    Noise of a simulated installed model counterrotation propeller at angle-of-attack and takeoff/approach conditions

    Get PDF
    Two modern high-speed advanced counterrotation propellers, F7/A7 and F7/A3 were tested in the NASA Lewis Research Center's 9- by 15-Foot Anechoic Wind Tunnel at simulated takeoff/approach conditions of 0.2 Mach. Both rotors were of similar diameter on the F7/A7 propeller, while the aft diameter of the F7/A3 propeller was 85 percent of the forward propeller to reduce tip vortex-aft rotor interaction. The two propellers were designed for similar performance. The propellers were tested in both the baseline configuration and installed configuration consisting of a simulated upstream nacelle support pylon and fuselage section. Acoustic measurements were made with a polar microphone probe which recorded sideline directivities at various azimuthal locations. Aerodynamic measurements were also made to establish propeller operating conditions. The propellers were run at initial blade setting angles adjusted to achieve equal forward/aft torque ratios at angle of attack with the pylon and fuselage simulation in place. Data are presented for propeller operation at 80 and 90 percent of design speed (the forward rotor design tip speed was 238 m/sec (780 ft/sec). Both propellers were tested at the maximum rotor-rotor spacing of 14.99 cm (5.90 in.) based on the pitch change axis separation

    Captain William Coit

    Get PDF
    This is a brief biography of Captain William Coit. It serves as an introduction to the Orderly Book of Moses Fargos for the use of William Coit\u27s company which is the 4th Company and 6th Regiment under Colonel Samuel Holden Parsons

    Stable gauged maps

    Get PDF
    We give an introduction to moduli stacks of gauged maps satisfying a stability conditition introduced by Mundet and Schmitt, and the associated integrals giving rise to gauged Gromov-Witten invariants. We survey various applications to cohomological and K-theoretic Gromov-Witten invariants.Comment: Survey for the 2015 AMS Summer Institute on Algebraic Geometry. Split off from the more technical paper "Properness for scaled gauged maps" [arXiv:1606.01383]. There is still substantial overlap between the two papers. This version has minor correction

    Geochemical support for a climbing habit within the Paleozoic seed fern genus Medullosa

    Get PDF
    A long-standing problem in paleobotany is the accurate identification of the growth habits and statures of fossil plants. Tissue-specific analysis of stable carbon isotope ratios in plant fossils can provide an independent perspective on this issue. Lignin, a fundamental biopolymer providing structural support in plant tissues and the second most abundant organic material in plants, is ^(13)C depleted by several parts per thousand, averaging 4.1‰, relative to other plant constructional materials (e.g. cellulose). With this isotopic difference, the biochemical structural composition of ancient plants (and inferred stature) can be interrogated using microscale in situ isotope analysis between different tissues in fossils. We applied this technique to a well-preserved specimen of the Late Paleozoic seed plant Medullosa, an extinct genus with a variety of growth habits that includes several enigmatic yet abundant small-stemmed species widely found in calcium carbonate concretions (“coal balls”) in the Pennsylvanian coal beds of Iowa, USA. It remains unclear which of the medullosans were freestanding, and recent analysis of the medullosan vascular system has shown that this system provided little structural support to the whole plant. The leading hypothesis for small-stemmed medullosan specimens predicts that cortical tissues could have provided additional structural support, but only if they were lignified. The expected isotopic difference between lignified tissue and unlignified tissue is smaller than that expected from pure extracts, for the simple reason that even woody tissues maximally contain 40% lignin (by mass). This reduces the expected maximum difference between weakly and heavily lignified tissues by 60%, down to ~0.5‰–2‰. Analysis of the medullosan stem reveals a consistent difference in isotope ratios of 0.7‰–1.0‰ between lignified xylem and cortical tissues. This implies low abundances of lignin (between 0% and 11%) within the cortex. This inferred structural biochemistry supports hypotheses that the peripheral portions of these medullosan stems were not biomechanically reinforced to permit the plants to grow as freestanding, arborescent trees. A number of climbing or scandent medullosans have been identified in the fossil record, and this mode of growth has been suggested to be common within the group on the basis of observations from comparative biomechanics, hydraulics, and development. Finally, this mode of growth is common in several clades of stem group seed plants, including Lyginopteris and Callistophyton, along with Medullosa. This study provides further support for ideas that place a great portion of early seed plant diversity under the canopy, rather than forming it

    Leeds Free School Meals Research Project (Phase 2 Report: Findings from the pilot phase Leeds Metropolitan University)

    Get PDF
    Free school meals aim to provide a “nutritional safety net” for the poorest UK children. Yet it is estimated that up to 30% of those entitled do not take up this entitlement. In Leeds approximately 6,000 children do not take the free school meals that they are entitled to. National and local targets are for 100% take up. Phase 2 of the Leeds Free School Meal Research Project aimed to develop, implement and evaluate a series of interventions to increase the uptake of free school meals. The interventions were tested in ten Leeds schools between December 2007 and October 2008. The research was undertaken by the Department of Nutrition & Dietetics within The Centre of Food Nutrition and Health at Leeds Metropolitan University on behalf of Education Leeds

    Literature Review - Health behaviour change models and approaches for families and young people to support HEAT 3: Child Healthy Weight Programmes

    Get PDF
    The literature review has been commissioned by NHS Health Scotland to review the health behaviour change models and approaches for families, children and young people to support the development and delivery of effective child healthy weight programmes. Despite the consistent recommendations from NICE and SIGN for the inclusion of behavioural components in child healthy weight programmes, there is little information on effectiveness of specific techniques and which to incorporate. The aim was therefore to provide information on which specific behavioural treatment components, behaviour change models and approaches should underpin clinical guidelines and childhood obesity treatment programmes. Secondly, in light of recommendations for programmes to be delivered by appropriately trained professionals, the review aimed to identify the skills and competencies required and resources and training available for effective delivery of the behavioural components. The outcomes of the literature review will be applied in enhancing the guidance for practitioners involved in the development and delivery of effective child healthy weight programmes; and thereby support achievement of the Scottish Government’s HEAT 3 target aimed at monitoring the attendance and completion of approved ’child healthy weight intervention programmes’. The report includes the background, aims, and objectives, sets out the scope of the review, presents a brief description of the methods and main findings. The methods and stakeholder views are then presented followed by a discussion of the implications for applying the evidence in practice and further research recommendations
    corecore