219,027 research outputs found

    Some university students are more equal than others: Evidence from England

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    This paper estimates the efficiency of students in English universities using Data Envelopment Analysis (DEA) and a new dataset which is able to capture the behaviour of university students. Taking as the output the classification of a university degree, we use as inputs teaching hours and quality, entry qualifications, and the effort level. We find that university students differ in terms of the efficiency with which they use inputs in producing good degrees. In a second stage, we explore the determinants of the efficiency of university students using a truncated regression model. Higher student efficiency is found to be positively and significantly related to university size, and negatively and significantly related to the proportion of part-time students and the number of academic staff. The quality of a university has no significant impact on the efficiency of its students once endogeneity of university quality is controlled for.

    Towards Long-endurance Flight: Design and Implementation of a Variable-pitch Gasoline-engine Quadrotor

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    Majority of today's fixed-pitch, electric-power quadrotors have short flight endurance (<< 1 hour) which greatly limits their applications. This paper presents a design methodology for the construction of a long-endurance quadrotor using variable-pitch rotors and a gasoline-engine. The methodology consists of three aspects. Firstly, the rotor blades and gasoline engine are selected as a pair, so that sufficient lift can be comfortably provided by the engine. Secondly, drivetrain and airframe are designed. Major challenges include airframe vibration minimization and power transmission from one engine to four rotors while keeping alternate rotors contra-rotating. Lastly, a PD controller is tuned to facilitate preliminary flight tests. The methodology has been verified by the construction and successful flight of our gasoline quadrotor prototype, which is designed to have a flight time of 2 to 3 hours and a maximum take-off weight of 10 kg.Comment: 6 page

    Exploring relationships between touch perception and surface physical properties

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    This paper reports a study of materials for confectionery packaging. The aim was to explore the touch perceptions of textures and identify their relationships with the surfaces' physical properties. Thirty-seven tactile textures were tested including 22 cardboards, nine flexible materials and six laminate boards. Semantic differential questionnaires were administered to assess responses to touching the textures against six word pairs: warm-cold, slippery-sticky, smooth,-rough, hard-soft, bumpy-flat, and wet-dry. Four physical measurements were conducted to characterize the surfaces' roughness, compliance, friction, and the rate of cooling of an artificial finger when touching the surface. Correlation and regression analyses were carried out to identify the relationships between the people's responses and the physical measurements. Results show that touch perception is often associated with more than one physical property, and the strength and form of the combined contribution can be represented by a regression model. © 2009 Chen, Shao, Barnes, Childs, & Henson
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