3,281 research outputs found

    Generalized Newton-Raphson trajectory optimization-generator 1

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    Computer program constructs a sequence of optimal solutions to dynamically-approximate linear equations. Specification of the number and type of subarcs in the optimal solution allows simultaneous satisfaction of all switching criteria

    Absolute Calibration of a Large-diameter Light Source

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    A method of absolute calibration for large aperture optical systems is presented, using the example of the Pierre Auger Observatory fluorescence detectors. A 2.5 m diameter light source illuminated by an ultra--violet light emitting diode is calibrated with an overall uncertainty of 2.1 % at a wavelength of 365 nm.Comment: 15 pages, 8 figures. Submitted to JINS

    Generation of folk song melodies using Bayes transforms

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    The paper introduces the `Bayes transform', a mathematical procedure for putting data into a hierarchical representation. Applicable to any type of data, the procedure yields interesting results when applied to sequences. In this case, the representation obtained implicitly models the repetition hierarchy of the source. There are then natural applications to music. Derivation of Bayes transforms can be the means of determining the repetition hierarchy of note sequences (melodies) in an empirical and domain-general way. The paper investigates application of this approach to Folk Song, examining the results that can be obtained by treating such transforms as generative models

    Impacts Of The Aggregate Economic And Financial Conditions On Output In An Emerging Economy

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    This study formulates the theoretical model based on the money market equilibrium, the goods market equilibrium, and an augmented aggregate supply function. The sample ranges from 1996.Q1 to 2009.Q3 and has 55 observations. Applying the generalized autoregressive conditional heteroskedasticity (GARCH) model, this paper finds that Brazilā€™s real GDP is positively impacted by real M2 money supply, the real stock price, world output and the expected inflation rate and is negatively influenced by the government deficit as a percent of GDP, the real BRL/USD exchange rate and the U.S. Treasury bill rate. The first and third quarters exhibit seasonal effects. Therefore, expansionary monetary policy is more effective than deficit-financed expansionary fiscal policy, and pursuing real appreciation, promoting a robust stock market, and maintaining a strong world economy will benefit the Brazilian economy

    3D virtual worlds as environments for literacy learning

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    Background: Although much has been written about the ways in which new technology might transform educational practice, particularly in the area of literacy learning, there is relatively little empirical work that explores the possibilities and problems - or even what such a transformation might look like in the classroom. 3D virtual worlds offer a range of opportunities for children to use digital literacies in school, and suggest one way in which we might explore changing literacy practices in a playful, yet meaningful context. Purpose: This paper identifies some of the key issues that emerged in designing and implementing virtual world work in a small number of primary schools in the UK. It examines the tensions between different discourses about literacy and literacy learning and shows how these were played out by teachers and pupils in classroom settings.Sources of evidence: Case study data are used as a basis for exploring and illustrating key aspects of design and implementation. The case study material includes views from a number of perspectives including classroom observations, chatlogs, in-world avatar interviews with teachers and also pupils, as well as the authorā€™s field notes of the planning process with accompanying minutes and meeting documents.Main argument: From a Foucauldian perspective, the article suggests that social control of pedagogical practice through the regulation of curriculum time, the normalisation of teaching routines and the regimes of individual assessment restricts teachersā€™ and pupilsā€™ conceptions of what constitutes literacy. The counternarrative, found in recent work in new litearcies (Lankshear & Knobel, 2006) provides an attractive alternative, but a movement in this direction requires a fundamental shift of emphasis and a re-conceptualisation of what counts as learning.Conclusions: This work on 3D virtual worlds questions the notion of how transformative practice can be achieved with the use of new technologies. It suggests that changes in teacher preparation, continuing professional development as well as wider educational reform may be needed

    Numerical validation of scaling laws for stratified turbulence

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    This is the final version. Available from Cambridge University Press via the DOI in this record.ā€ÆRecent theoretical progress using multiscale asymptotic analysis has revealed various possible regimes of stratified turbulence. Notably, buoyancy transport can either be dominated by advection or diffusion, depending on the effective PĆ©clet number of the flow. Two types of asymptotic models have been proposed, which yield measurably different predictions for the characteristic vertical velocity and length scale of the turbulent eddies in both diffusive and non-diffusive regimes. The first, termed a ā€˜single-scale modelā€™, is designed to describe flow structures having large horizontal and small vertical scales, while the second, termed a ā€˜multiscale modelā€™, additionally incorporates flow features with small horizontal scales, and reduces to the single-scale model in their absence. By comparing predicted vertical velocity scaling laws with direct numerical simulation data, we show that the multiscale model correctly captures the properties of strongly stratified turbulence within regions dominated by small-scale isotropic motions, whose volume fraction decreases as the stratification increases. Meanwhile its single-scale reduction accurately describes the more orderly, layer-like, quiescent flow outside those regions.U.S. Department of EnergyJ.S. McDonnell Foundatio

    Robust Estimators in Generalized Pareto Models

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    This paper deals with optimally-robust parameter estimation in generalized Pareto distributions (GPDs). These arise naturally in many situations where one is interested in the behavior of extreme events as motivated by the Pickands-Balkema-de Haan extreme value theorem (PBHT). The application we have in mind is calculation of the regulatory capital required by Basel II for a bank to cover operational risk. In this context the tail behavior of the underlying distribution is crucial. This is where extreme value theory enters, suggesting to estimate these high quantiles parameterically using, e.g. GPDs. Robust statistics in this context offers procedures bounding the influence of single observations, so provides reliable inference in the presence of moderate deviations from the distributional model assumptions, respectively from the mechanisms underlying the PBHT.Comment: 26pages, 6 figure

    ā€˜That eccentric use of land at the top of the hillā€™: Cemeteries and stories of the city

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    Most contemporary research accounts for conflict within cemetery space, but does not consider the potentially contested and poorly understood role of cemeteries within their broader cityscape. This study draws on stories from cemetery managers across England and Wales to narrate this multifunctionality, as they hold the pivotal role which oversees both the day-to-day running of the cemetery, and its strategic role within a given municipality. The study outlines how cemeteries hold multiple functions in the cities in which they are located, specifically contributing to greenspace or green infrastructure, civic identity and local place attachment. These varying city level roles in turn impact on what is deemed (il)legitimate behaviour within the cemetery. Moreover, they raise important considerations for urban planners and policymakers who currently have little guidance on planning for new or existing cemeteries but are critical in the ongoing successful development of cities
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