247 research outputs found

    Enhancing the effectiveness of student feedback and support in a distance learning context

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    This is an ESCalate development project led by Chris Kynch of St Martins College and completed in 2002. Distance learning is seen as a popular flexible solution to learning while maintaining a job and other commitments. Nevertheless the drop out rate is typically high. One view is that only highly self motivated students succeed. Another is that students may acclimatise to distance learning. Support and feedback could be important in this process, and especially salient for school placements. Understanding the nature of feedback and support and its impact on students has been identified as the key issue to be taken forward by this research project. The project was initiated by a team who are responsible for an innovative modular flexible distance learning course leading initially to the Post Graduate Certificate in Education (PGCE). The course has proved increasingly popular with students and, perhaps because it was innovative, generated interest from the media and the TTA as well as other educational institutions. Although successful courses leading to qualified teacher status for Secondary school teachers have long been offered by the Open University, primary courses have proved more challenging, and notably an Ofsted report led to programme closure. Because of the success of the Secondary courses, it is clearly possible to assure the quality of school placements. However there are distinctive challenges for smaller schools, schools which are geographically distant from the higher education provider, and schools which are thinly spread over remote rural areas. One or more of these characteristics tend to be typical of primary schools. One of the reasons for the successful launch, from Ambleside, of the distance learning course which was studied by the research project, was the innovative approaches of the college to ensure consistent, high quality primary school placements for student teachers in small, geographically dispersed schools which are typical of North Lancashire and Cumbria. The research project worked with the earliest cohorts, so that students experienced rapid developments in the shape, design and delivery of the programme and constituent parts, and also the very fast learning curve of tutors and programme leaders as they engaged with the emerging challenges of 'blended learning' at a distance. The interviews, especially of students from the first cohort, reflect this formation stage, and how at the start the programme was engaging with both distance and technology mediated learning. The experience of developing the course and the early challenges is likely to be of interest to others who are embarking 'from scratch' in this field. However, distance learning and technology mediated learning may take many forms, making it difficult to draw comparisons between different courses and contexts. It includes an interim and final project report

    A high resolution spectral element approximation of viscoelastic flows in axisymmetric geometries using a DEVSS-G/DG formulation

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    The discretisation of benchmark viscoelastic flow problems in axisymmetric geometries using the spectral element method is considered. The computations are stabilized using the DEVSS-G/DG formulation of the governing equations. A decoupled approach is employed in which the conservation equations are solved for velocity and pressure and the constitutive equation (Oldroyd-B and Giesekus) are solved for the polymeric component of the extra-stress tensor. The method is validated for the start-up of transient Poiseuille flow for which an analytical solution exists. A comprehensive set of results is presented for flow past a fixed sphere for the Oldroyd B and Giesekus models. Excellent agreement is found with results in the literature on the drag experienced by the sphere. Evidence is provided which shows the existence of a limiting Weissenberg number due to the inability to resolve the high gradients in axial stress in the wake of the sphere through polynomial enrichment. The shear-thinning property of the Giesekus model leads to a reduction in drag compared to the Oldroyd B model at equivalent values of the Weissenberg number and viscosity ratio. The numerical simulations eventually fail to converge for the Giesekus model which suggests that factors other than solely extensional properties are responsible for this behaviour. The influence of the Reynolds number and, for the Giesekus model, the mobility parameter on the drag coefficient is also investigated and discussed

    Numerical investigation of sedimentation in viscoelastic fluids using spectral element methods

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    In this thesis we consider the problem of a falling sphere within a fluid. We are primarily interested in incompressible fluids exhibiting so-called viscoelastic properties in which a range of phenomena have been observed experimentally. These phenomena are typically manifest in the presence of a negative wake, an overshoot of the velocity of the falling sphere and drag reduction as well as enhancement in some cases. We consider fluid models which have been designed to capture these effects and use them to simulate the flow numerically with the intention of gaining an insight into the observed phenomena. We begin with the most basic fluid models in order to validate our scheme, considering both Stokes and Newtonian fluids before progressing to viscoelastic fluid models in a range of problems to ensure the robustness of our solver. Our scheme ultimately utilises the Spectral Element Method(SEM) combined with a Discontinuous Galerkin(DG) treatment of the constituitive equation along with a DEVSS-G stabilisation term in the momentum equation. We employ an Arbitrary Lagrangian Eulerian(ALE) scheme when simulating a falling sphere. Our simulations successfully capture the drag reduction when moving fluid past a fixed sphere as well as velocity overshoot for the sedimenting sphere, although we have failed to capture the presence of a negative wake thus far. Excellent agreement with the literature is demonstrated for the benchmarks considered in both planar and axisymmetric geometries

    Resolving the sign conflict problem for hp–hexahedral Nédélec elements with application to eddy current problems

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    The eddy current approximation of Maxwell’s equations is relevant for Magnetic Induction Tomography (MIT), which is a practical system for the detection of conducting inclusions from measurements of mutual inductance with both industrial and clinical applications. An MIT system produces a conductivity image from the measured fields by solving an inverse problem computationally. This is typically an iterative process, which requires the forward solution of a Maxwell’s equations for the electromagnetic fields in and around conducting bodies at each iteration. As the (conductivity) images are typically described by voxels, a hexahedral finite element grid is preferable for the forward solver. Low order Nédélec (edge element) discretisations are generally applied, but these require dense meshes to ensure that skin effects are properly captured. On the other hand, hp–Nédélec finite elements can ensure the skin effects in conducting components are accurately captured, without the need for dense meshes and, therefore, offer possible advantages for MIT. Unfortunately, the hierarchic nature of hp–Nédélec basis functions introduces edge and face parameterisations leading to sign conflict issues when enforcing tangential continuity between elements. This work describes a procedure for addressing this issue on general conforming hexahedral meshes and an implementation of a hierarchic hp–Nédélec finite element basis within the deal.II finite element library. The resulting software is used to simulate Maxwell forward problems, including those set on multiply connected domains, to demonstrate its potential as an MIT forward solver

    Accelerating magnetic induction tomography‐based imaging through heterogeneous parallel computing

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    Magnetic Induction Tomography (MIT) is a non‐invasive imaging technique, which has applications in both industrial and clinical settings. In essence, it is capable of reconstructing the electromagnetic parameters of an object from measurements made on its surface. With the exploitation of parallelism, it is possible to achieve high quality inexpensive MIT images for biomedical applications on clinically relevant time scales. In this paper we investigate the performance of different parallel implementations of the forward eddy current problem, which is the main computational component of the inverse problem through which measured voltages are converted into images. We show that a heterogeneous parallel method that exploits multiple CPUs and GPUs can provide a high level of parallel scaling, leading to considerably improved runtimes. We also show how multiple GPUs can be used in conjunction with deal.II, a widely‐used open source finite element library

    Survival Strategies and Power amongst the Poorest in a West Bengal Village

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    SUMMARY Focusing on ‘people's history’ challenges the assumption that poor people are passive, followers, or apolitical, by identifying ways in which poor people are makers of their own histories. By adapting a ‘people's history’ approach to the geographical study of one village in West Bengal, and concentrating particularly on survival strategies used by poorest women and children, this article shows that the rural poorest are active in an informal economy through which they operate much of their business, and that they have clear views on the characteristics of rich people. Survival strategies considered include the use of common property resources; changes in consumption patterns; share?rearing of livestock; and mutual support networks. Each is put in the context of a wider literature, and policy implications evaluated to determine the possibility of external support for such indigenous coping mechanisms. Resumé Stratégies de survie et pouvoir parmi les catégories sociales les plus démunies du Bengale de l'Ouest Prendre comme point de départ ‘l'histoire individuelle’ remet en question l'hypothèse que les pauvres sont passifs, soumis et sans conviction politique, lorsque l'on identifie les différentes manières dont ils ont construit leur propre destin. Par l'adaptation de l'approche qui prend en considération les données d'une ‘histoire personnelle’, et son utilisation dans l'analyse géographique d'un village du Bengale de l'Ouest qui se concentre tout particulièrement sur les stratégies développées par les femmes et les enfants les plus pauvres afin de survivre, cet article démontre que les pauvres dans l'environment rural sont actifs dans le secteur informal de l'économie dans lequel ils conduisent la plupart de leurs affaires, et qu'ils ont une perspective claire sur les caractéristiques des gens riches. Les stratégies de survie analysées comprennent l'exploitation des ressources des propriétés communales, les changements dans les rythmes de consommation, le partage des tâches dans le domaine de l'élevage, et des réseaux de support mutuel. Chacune de ces stratégies présentée dans le contexte d'une littérature plus élaborée, et dans celui des conséquences des mesures prises et réalisées, est évaluée de manière à déterminer les possibilités d'une aide externe à chacun de ces mécanismes de défense utilisés. Resumen Estrategias de sobrevivencia y poder entre los más pobres en una aldea de Bengala Occidental El enfoque “historia de la gente” desafía el supuesto de que los despodeídos son pasivos, sumisos y apolíticos, mediante la identificación de vías a través de las cuales estas personas hacen su propia historia. Este artículo adapta el enfoque “historia de la gente” a un estudio geográfico de una aldea de Bengala occidental, concentrándose especialmente en las estrategias de sobrevivencia usadas por mujeres y niños desposeídos demostrando que en el área rural los más pobres son activos en una economía informal a través de la cual operan la mayor parte de sus quehaceres y que tienen visiones claras sobre las características de los ricos. Las estrategias de sobrevivencia consideradas incluyen el uso de racursos de propiedad comunitaria, cambios en los patrones de consumo, crianza del ganado compartida y redes mutuales de apoyo. Cada una es colocada en el contexto de una literatura amplia e implicaciones políticas evaluadas para determinar la posibilidad de obtener apoyo externo para estos mecanismos de lucha nativos
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