31,317 research outputs found

    Transforming Learning Through Online Storytelling: : 'Making the News' Evaluation Report

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    This report presents the findings from an independent evaluation undertaken by the University of Hertfordshire of the ‘Making The News project’ as it functioned within the East of England Broadband Network region (E2BN). Making the News represents a set of simple tools that allow teachers and students to rapidly produce ‘news’ stories and publish them on line. It was developed by the Centre for New Media at the Open University in conjunction with E2BNFinal Published versio

    Effect of signal jitter on the spectrum of rotor impulsive noise

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    The effect of randomness or jitter of the acoustic waveform on the spectrum of rotor impulsive noise is studied because of its importance for data interpretation. An acoustic waveform train is modelled representing rotor impulsive noise. The amplitude, shape, and period between occurrences of individual pulses are allowed to be randomized assuming normal probability distributions. Results, in terms of the standard deviations of the variable quantities, are given for the autospectrum as well as special processed spectra designed to separate harmonic and broadband rotor noise components. Consideration is given to the effect of accuracy in triggering or keying to a rotor one per revolution signal. An example is given showing the resultant spectral smearing at the high frequencies due to the pulse signal period variability

    An experimental evaluation of the application of the Kirchhoff formulation for sound radiation from an oscillating airfoil

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    The Kirchhoff integral formulation is evaluated for its effectiveness in quantitatively predicting the sound radiated from an oscillating airfoil whose chord length is comparable with the acoustic wavelength. A rigid airfoil section was oscillated at samll amplitude in a medium at rest to produce the sound field. Simultaneous amplitude and phase measurements were made of surface pressure and surface velocity distributions and the acoustic free field. Measured surface pressure and motion are used in applying the theory, and airfoil thickness and contour are taken into account. The result was that the theory overpredicted the sound pressure level by 2 to 5, depending on direction. Differences are also noted in the sound field phase behavior


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    Agricultural and Food Policy,

    The LHC Discovery Potential of a Leptophilic Higgs

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    In this work, we examine a two-Higgs-doublet extension of the Standard Model in which one Higgs doublet is responsible for giving mass to both up- and down-type quarks, while a separate doublet is responsible for giving mass to leptons. We examine both the theoretical and experimental constraints on the model and show that large regions of parameter space are allowed by these constraints in which the effective couplings between the lightest neutral Higgs scalar and the Standard-Model leptons are substantially enhanced. We investigate the collider phenomenology of such a "leptophilic" two-Higgs-doublet model and show that in cases where the low-energy spectrum contains only one light, CP-even scalar, a variety of collider processes essentially irrelevant for the discovery of a Standard Model Higgs boson (specifically those in which the Higgs boson decays directly into a charged-lepton pair) can contribute significantly to the discovery potential of a light-to-intermediate-mass (m_h < 140 GeV) Higgs boson at the LHC.Comment: 25 pages, LaVTeX, 11 figures, 1 tabl

    Dynamic response and stability of a composite prop-fan model

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    Results are presented for blade response and stability during wind tunnel tests of a 62.2 cm diameter model of a prop-fan, advanced turboprop, with swept graphite/epoxy composite blades. Measurements of dynamic response were made with the rotor mounted on an isolated nacelle, with varying tilt for nonuniform inflow, at flow speeds from 0.36 to 0.9 Mach number. The blade displayed no instabilities over the operating range tested, up to 0.9 Mach number and 10,000 RPM. Measurements are compared with those for other prop-fan models of both solid metal and graphite composite construction. The swept composite blade had less response than an unswept composite blade. Composite blades had more response than metal blades. Measurements are compared with theoretically based predictions. The 1-P blade response was significantly overpredicted using unimproved methods and somewhat overpredicted using improved methods. Unexpectedly high 2-P strain levels were measured and suggest the presence of nonlinear effects on blade response

    Results of the 1986 NASA/FAA/DFVLR main rotor test entry in the German-Dutch wind tunnel (DNW)

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    An acoustics test of a 40%-scale MBB BO-105 helicopter main rotor was conducted in the Deutsch-Niederlandischer Windkanal (DNW). The research, directed by NASA Langley Research Center, concentrated on the generation and radiation of broadband noise and impulsive blade-vortex interaction (BVI) noise over ranges of pertinent rotor operational envelopes. Both the broadband and BVI experimental phases are reviewed, along with highlights of major technical results. For the broadband portion, significant advancement is the demonstration of the accuracy of prediction methods being developed for broadband self noise, due to boundary layer turbulence. Another key result is the discovery of rotor blade-wake interaction (BWI) as an important contributor to mid frequency noise. Also the DNW data are used to determine for full scale helicopters the relative importance of the different discrete and broadband noise sources. For the BVI test portion, a comprehensive data base documents the BVI impulsive noise character and directionality as functions of rotor flight conditions. The directional mapping of BVI noise emitted from the advancing side as well as the retreating side of the rotor constitutes a major advancement in the understanding of this dominant discrete mechanism

    Dynamic response of two composite prop-fan models on a nacelle/wing/fuselage half model

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    Results are presented for blade response wind tunnel tests of two 62.2 cm diameter Prop-Fan (advanced turboprop) models with swept and unswept graphite/epoxy composite blades. Measurements of dynamic response were made with the rotors mounted on a simulated nacelle/wing/fuselage model, with varying tilt, at flow speeds up to 0.85 Mach number. The presence of the wing, downstream of the rotor, induced 1-P responses that were about twice those previously measured for an isolated nacelle installation. The swept blade had less 1-P response than the unswept (straight) blade. The 2-P response was significant for both blades, and was closely correlated to wing lift. Higher order response was not important for the straight blade, but possibly important for the swept blade near critical speeds, due to the proximity of the blade tips to the wing leading edge. Measurements are compared with theoretically based prediction. Correlations between calculated and measured 1-P response were good for the straight blade, and fair for the swept blade. Improvements to the calculation method were identified and implemented

    Associations between physical activity in adolescence and health behaviours, well-being, family and social relations.

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    This is an Accepted Manuscript of an article published by Taylor & Francis Group in International Journal of Health Promotion and Education on 16 September 2014, available online at: https://doi.org/10.1080/14635240.2014.923287Across Europe and North America, few young people meet the recommended levels of physical activity (PA) of 1 hour of moderate to vigorous PA per day. However, the lives of young people cannot simply be polarised as either completely sedentary or active. Drawing on findings from the World Health Organization Health Behaviour in School-aged Children cross sectional international study, this paper examines the domains of adolescent life associated with young people's participation in overall PA, including health behaviours, social relationships and family activities. Consideration is also given to gender differences. Information in England was collected from 4404 students aged 11, 13 and 15 years, using anonymised self-completed questionnaires. Physical aspects of lifestyle were determined using internationally validated items for measuring PA that met international guidelines for activity and the frequency and duration of vigorous exercise undertaken during leisure activities. Separate analyses were conducted for boys and girls. Levels of PA and vigorous exercise were compared using the chi-squared test for trend. The findings draw attention to the value for the health and well-being of young people participating in some form of PA, even if they do not meet the recommended levels. Medium levels of PA appear to be associated with high levels of life satisfaction, self-rated health and an improved sense of body image. Significant health gains are likely to be made for adolescents in encouraging sedentary young people to undertake some form of PAPeer reviewedFinal Accepted Versio
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