27,905 research outputs found

    Exchange of information about physical education to support the transition of pupils from primary and secondary school

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    The purpose of this study was to identify how information about physical education is exchanged between secondary schools and their respective feeder primary schools, what information is exchanged and how this information is used. A secondary purpose was to look at whether there is any relationship between schools engaging in liaison activities and exchanging information about physical education, and between exchanging information and the number of associated secondary schools to which pupils are sent or feeder primary schools from which pupils are received. Questionnaires were sent to 177 secondary and 538 feeder primary schools. Responses from 80 secondary schools and 299 primary schools showed that the highest percentage of teachers exchanged information through written documentation, followed by discussion at cross phase liaison meetings. The type of information exchanged by the highest percentage of teachers was identified as generic information about key stage 2 and 3 of the National Curriculum for Physical Education (NCPE) areas of activity and schemes of work, rather than information about the specific physical education content covered or information about individual pupils, such as levels of attainment or ability. Further, results suggest that information may be used for pastoral purposes and that only a small percentage of teachers used the information exchanged to plan for continuity and progression in the physical education curriculum. There was a significant positive relationship between engagement in liaison activities and information received about the physical education curriculum followed by pupils, but a significant negative relationship for primary teachers between the number of different secondary schools to which pupils' progress and knowledge about the key stage 3 schemes of work that Year 6 pupils will follow in their associated secondary schools. These results are discussed in relation to continuity and progression in physical education in the transfer of pupils from primary to secondary schools

    A study of current practice in liaison between primary and secondary schools in physical education

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    The purpose of this study was to investigate current practice in liaison between primary and secondary schools to promote continuity and progression in physical education during the transfer of pupils from Key Stage 2 to Key Stage 3 and to identify constraints to engaging in liaison activities. A questionnaire was completed by the head of the physical education department in secondary schools in five local education authorities in England that received pupils from primary schools in year 7 (n = 80) and by the physical education coordinator of the primary feeder schools of those secondary schools that responded to the questionnaire (n = 299). Results showed that 32 (43.8%) secondary teachers and 157 (53.4%) primary teachers identified that they had established contacts with their primary feeder schools or associated secondary schools respectively; and 49 (64.5%) secondary teachers but 114 (39.6%) primary teachers identified that currently they were engaged in liaison activities. There was a discrepancy between the percentages of teachers who indicated they had contacts with their primary feeder schools or associated secondary schools respectively, and who indicated they were engaged in liaison activities with them. These results suggested that contacts with and/or engagement in liaison activities between primary and secondary schools were not consistent across schools. A range of constraints for developing effective contacts/liaison activities were identified, with time being identified as the major constraint by both primary and secondary teachers. A range of suggestions for overcoming the constraints were also identified. These results are discussed in relation to findings from studies looking at liaison in other subjects and also in relation to the implications for schools

    Towards obtaining robust boundary condition parameters to aid accuracy in FEA thermal error predictions

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    Finite Element Analysis (FEA) is used as a design tool within engineering industries due to the capability for rapid summative analysis accompanied by the visual aid. However, to represent realistic behaviour, FEA relies heavily on input parameters which must ideally be based on true figures such as data from experimental testing which sometimes requires time-consuming testing regimes. In the case of machine tool assemblies where complex structural joints and linkages are present, access to those areas can be a primary constraint to obtaining related boundary parameters such as heat flow across joints, for which, assumptions are incorporated to the FEA model which in effect increase the uncertainty in the FEA predictions. Similarly, in the case of thermal error modelling, simplifications are made when representing thermal boundary conditions such as the application of a uniform convection parameter to an assembly with parts assembled in both horizontal and vertical orientations. This research work aims to reduce the number of assumptions by providing experimentally obtained thermal boundary condition parameters. This work acknowledges experimental regimes that focus on obtaining thermal parameters related to the conduction across assembly joints (Thermal Contact Conductance-TCC) and measures the convection around areas such as belt drives and rotating parts to obtain convection parameters as inputs to the FEA. It provides TCC parameters for variable interfacial behaviour based on the varying contact pressure and the heat flow through dry and oiled contacts such as the conduction from spindle bearings to the surrounding housing and conduction from guideways into the associated assembly through carriages and contact bearings. It provides convection parameters across the test mandrel rotating at different speeds and around stationary structures such as convection parameters observed during TCC tests. It also provide details on the methods used to obtain all these parameters such as the use of thermal imaging, sensors placements and methods to obtain these boundary condition parameters. The significance of this work is to improve dramatically FEA thermal predictions, which are a critical part of engineering design. Although the focus is on machine tool design, the process and parameters can equally be applied to other areas of thermodynamic behaviour

    Efficient estimation by FEA of machine tool distortion due to environmental temperature perturbations

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    Machine tools are susceptible to exogenous influences, which mainly derive from varying environmental conditions such as the day and night or seasonal transitions during which large temperature swings can occur. Thermal gradients cause heat to flow through the machine structure and results in non-linear structural deformation whether the machine is in operation or in a static mode. These environmentally stimulated deformations combine with the effects of any internally generated heat and can result in significant error increase if a machine tool is operated for long term regimes. In most engineering industries, environmental testing is often avoided due to the associated extensive machine downtime required to map empirically the thermal relationship and the associated cost to production. This paper presents a novel offline thermal error modelling methodology using finite element analysis (FEA) which significantly reduces the machine downtime required to establish the thermal response. It also describes the strategies required to calibrate the model using efficient on-machine measurement strategies. The technique is to create an FEA model of the machine followed by the application of the proposed methodology in which initial thermal states of the real machine and the simulated machine model are matched. An added benefit is that the method determines the minimum experimental testing time required on a machine; production management is then fully informed of the cost-to-production of establishing this important accuracy parameter. The most significant contribution of this work is presented in a typical case study; thermal model calibration is reduced from a fortnight to a few hours. The validation work has been carried out over a period of over a year to establish robustness to overall seasonal changes and the distinctly different daily changes at varying times of year. Samples of this data are presented that show that the FEA-based method correlated well with the experimental results resulting in the residual errors of less than 12 ÎŒm

    FEA-based design study for optimising non-rigid error detection on machine tools

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    Non-rigid-body behaviour can have a considerable effect on the overall accuracy performance of machine tools. These errors originate from bending of the machine structure due to change in distribution of its own weight or from movement of the workpiece and fixture. These effects should be reduced by good mechanical design, but residual errors can still be problematic due to realistic material and cost limitations. One method of compensation is to measure the deformation directly with sensors embedded in a metrology frame. This paper presents an FEA-based design study which assesses finite stiffness effects in both the machine structure and its foundation to optimise the sensitivity of the frame to the resulting errors. The study results show how a reference artefact, optimised by the FEA study, can be used to detect the distortion

    Five-Axis Machine Tool Condition Monitoring Using dSPACE Real-Time System

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    This paper presents the design, development and SIMULINK implementation of the lumped parameter model of C-axis drive from GEISS five-axis CNC machine tool. The simulated results compare well with the experimental data measured from the actual machine. Also the paper describes the steps for data acquisition using ControlDesk and hardware-in-the-loop implementation of the drive models in dSPACE real-time system. The main components of the HIL system are: the drive model simulation and input – output (I/O) modules for receiving the real controller outputs. The paper explains how the experimental data obtained from the data acquisition process using dSPACE real-time system can be used for the development of machine tool diagnosis and prognosis systems that facilitate the improvement of maintenance activities

    Stability of Influence Maximization

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    The present article serves as an erratum to our paper of the same title, which was presented and published in the KDD 2014 conference. In that article, we claimed falsely that the objective function defined in Section 1.4 is non-monotone submodular. We are deeply indebted to Debmalya Mandal, Jean Pouget-Abadie and Yaron Singer for bringing to our attention a counter-example to that claim. Subsequent to becoming aware of the counter-example, we have shown that the objective function is in fact NP-hard to approximate to within a factor of O(n1−ϔ)O(n^{1-\epsilon}) for any Ï”>0\epsilon > 0. In an attempt to fix the record, the present article combines the problem motivation, models, and experimental results sections from the original incorrect article with the new hardness result. We would like readers to only cite and use this version (which will remain an unpublished note) instead of the incorrect conference version.Comment: Erratum of Paper "Stability of Influence Maximization" which was presented and published in the KDD1

    e+e−→H+H−e^+e^-\to H^+H^- signals at LEP2 energies in the Minimal Supersymmetric Standard Model

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    In this paper we compare H+H−H^+H^- and W+W−W^+W^- into four-fermion production at centre-of-mass energies typical of LEP2 and somewhat larger. The theoretical framework considered is the Minimal Supersymmetric Standard Model. The interest in exploiting the e+e−e^+e^- CERN collider at values of s\sqrt s greater than 192 GeV could come from the discovery of Supersymmetric signals during runs at lower energy. If these indicate that a charged Higgs boson exists in the mass range \MH\approx95-105 GeV, then a few years of running at s=205−215\sqrt s=205-215 GeV and nominal luminosity could make the detection of such scalars feasible, in the purely leptonic channel τΜττΜτ\tau\nu_\tau\tau\nu_\tau and, for small \tb's, also in the semi-hadronic(leptonic) one jjτΜτ{jj}\tau\nu_\tau. Charged Higgs bosons of the above nature cannot be produced by the beam energies approved at present for LEP2. However, if runs beyond the so-called `192 GeV cryogenic limit' will be approved by the CERN Council, our selection procedure will enable us to establish the presence, or otherwise, of charged Higgs bosons in the mentioned mass rangeComment: 30 pages, latex, epsfig, 12 postscript figures, complete paper available at ftp://axpa.hep.phy.cam.ac.uk/stefano/cavendish_9615 and at http://www.hep.phy.cam.ac.uk/theory/papers
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