12,253 research outputs found

    Experimental study of noise reduction for an unstiffened cylindrical model of an airplane fuselage

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    Noise reduction measurements were made for a simplified model of an airplane fuselage consisting of an unstiffened aluminum cylinder 0.5 m in diameter by 1.2 m long with a 1.6-mm-thick wall. Noise reduction was first measured with a reverberant field pink-noise load on the cylinder exterior. Next, noise reduction was measured by using a propeller to provide a more realistic noise load on the cylinder. Structural resonance frequencies and acoustic reverberation times for the cylinder interior volume were also measured. Comparison of data from the relatively simple test using reverberant-field noise with data from the more complex propeller-noise tests indicates some similarity in both the overall noise reduction and the spectral distribution. However, all of the test parameters investigated (propeller speed, blade pitch, and tip clearance) had some effect on the noise-reduction spectra. Thus, the amount of noise reduction achieved appears to be somewhat dependent upon the spectral and spatial characteristics of the flight conditions. Information is also presented on cyclinder resonance frequencies, damping, and characteristics of propeller-noise loads

    The role of the Initial Teacher Training Coordinator in the school based element of partnership: to what extent does the Co-ordinator undertake supervision of aspects of quality assurance?

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    Over the last 14 years, Universities and colleges have organised school placements and award qualifications whilst teachers, acting as mentors take the lead in guiding, supervising and assessing students on lengthy teaching placements. Partnership developed quickly in response to legislation and Sheffield Hallam University was among the first of the Universities to 'sign up' to the new partnership model in 1992. The Partnership Survey 2006 reported on in this paper has focussed on the Senior Liaison Tutor with a view to finding out their views on their role, and perceived contributions to the quality assurance of the partnership. The survey focussed on some of the key issues identified in previous studies and meetings of the Partnership Management Board.</p

    The role of the initial teacher training co-ordinator: secondary headteachers' and ITT co-ordinators' perspectives

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    The roles of ITT co-ordinator (ITTC) and CPD co-ordinator have become well established in secondary schools in England. However there is usually a separation of responsibilities for these areas within schools. The introduction of a new Standards Framework and other government policies such as the remodelling of the workforce in schools (DfES, 2003, TDA, 2007a) provide schools with opportunity to revisit these roles. A consequence of remodelling has been a rapid expansion of support staff in schools to assist teachers and one aspect of this contractual change is that support staff are taking on administrative tasks, formerly done by teachers. A further aspect is that CPD Coordinators now have responsibility for staff development cross the wider workforce. During 2007, Schools have used remodelling as an opportunity to review their management structures throughout the school including the organisation of staff development and how the school is contributing to the training of new teachers. In this paper we consider how the role of the ITTC is changing using data from interviews with Head Teachers and ITTCs from a sample of secondary schools that are in partnership with Sheffield Hallam University. Data collection took place in April and May 2007.</p

    Experiments on the Chemotherapy of Blackhead in Turkeys

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    Infectious enterohepatitis, or blackhead, is often regarded as the most important disease of turkeys since all ages and breeds are susceptible and mortality is high. The yearly financial losses resulting from blackhead have stimulated increasing interest and experimentation on chemotherapy of this disease. Many compounds have been tested, but at the present time no other group of compounds seems to offer as much promise as the organic arsenicals. Several members of this class of compounds as well as a few non-arsenicals have been found to have a limited effect against the blackhead organism; but none, whether arsenical or non-arsenical, has thus far found widespread practical use among turkey raisers

    First detection of phase-dependent colliding wind X-ray emission outside the Milky Way

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    After having reported the detection of X-rays emitted by the peculiar system HD5980, we assess here the origin of this high-energy emission from additional X-ray observations obtained with XMM-Newton. This research provides the first detection of apparently periodic X-ray emission from hot gas produced by the collision of winds in an evolved massive binary outside the Milky Way. It also provides the first X-ray monitoring of a Luminous Blue Variable only years after its eruption and shows that the dominant source of the X-rays is not associated with the ejecta.Comment: 13 pages, 3 figures and 1 table, accepted for publication in ApJ (letters

    Applications of ethylene vinyl acetate as an encapsulation material for terrestrial photovoltaic modules

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    Terrestrial photovoltaic modules must undergo substantial reductions in cost in order to become economically attractive as practical devices for large scale production of electricity. Part of the cost reductions must be realized by the encapsulation materials that are used to package, protect, and support the solar cells, electrical interconnects, and other ancillary components. As many of the encapsulation materials are polymeric, cost reductions necessitate the use of low cost polymers. The performance and status of ethylene vinyl acetate, a low cost polymer that is being investigated as an encapsulation material for terrestrial photovoltaic modules, are described

    Near-Threshold Production of omega Mesons in the pp -> pp omega Reaction

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    The total cross section for omega production in the pp -> pp omega reaction has been measured at five c.m. excess energies from 3.8 to 30 MeV. The energy dependence is easily understood in terms of a strong proton-proton final state interaction combined with a smearing over the width of the state. The ratio of near-threshold phi and omega production is consistent with the predictions of a one-pion-exchange model and the degree of violation of the OZI rule is similar to that found in the pi-p -> n omega/phi reactions.Comment: Report in LaTeX2e. 12 pages with 2 eps figure

    Identification of possible intense historical geomagnetic storms using combined sunspot and auroral observations from East Asia

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    Comprehensive catalogues of ancient sunspot and auroral observations from East Asia are used to identify possible intense historical geomagnetic storms in the interval 210 BC-AD 1918. There are about 270 entries in the sunspot catalogue and about 1150 entries in the auroral catalogue. Special databases have been constructed in which the scientific information in these two catalogues is placed in specified fields. For the purposes of this study, an historical geomagnetic storm is defined in terms of an auroral observation that is apparently associated with a particular sunspot observation, in the sense that the auroral observation occurred within several days of the sunspot observation. More precisely, a selection criterion is formulated for the automatic identification of such geomagnetic storms, using the oriental records stored in the sunspot and auroral databases. The selection criterion is based on specific assumptions about the duration of sunspot visibility with the unaided eye, the likely range of heliographic longitudes of an energetic solar feature, and the likely range of transit times for ejected solar plasma to travel from the Sun to the Earth. This selection criterion results in the identification of nineteen putative historical geomagnetic storms, although two of these storms are spurious in the sense that there are two examples of a single sunspot observation being associated with two different auroral observations separated by more than half a (synodic) solar rotation period. The literary and scientific reliabilities of the East Asian sunspot and auroral records that define the nineteen historical geomagnetic storms are discussed in detail in a set of appendices. A possible time sequence of events is presented for each geomagnetic storm, including possible dates for both the central meridian passage of the sunspot and the occurrence of the energetic solar feature, as well as likely transit times for the ejected solar plasma. European telescopic sunspot drawings from the seventeenth century are also used to assess the credibility of some of the later historical geomagnetic storms defined solely by the East Asian sunspot and auroral records. These drawings cast doubt on a few of the associations between sunspot and auroral observations based entirely on the oriental records, at least to the extent that the occidental drawings provide a more realistic date for central meridian passage of the sunspot actually associated with a particular auroral observation. Nevertheless, on those occasions for which European sunspot drawings are available, the dates of all the pertinent East Asian sunspot and auroral observations are corroborated, apart from just one Chinese sunspot observation. The ancient historical observations of sunspots and aurorae are discussed briefly in terms of modern observations of great geomagnetic storms
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