26,628 research outputs found

    A new model for procuring e-books

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    This paper draws on a recent ground-breaking tender for e-books for higher education libraries in the UK. The strategy for the tender was informed by standard procurement practice and by the experience of acquiring other e-resources, particularly journals under the so-called big deal. Both are examined as background to the discussion of e-books in general and the tender in particular

    Formulas establish audio range inductance in beryllium coils

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    Mathematical modeling is used to determine the effects of resistance and capacitance upon the audio-inductance range of beryllium hammer coils and beryllium nylon-potted coils

    Factory Eco-Efficiency Modelling: Framework Development and Testing

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    Eco-efficiency is becoming an increasingly important organisational performance measure. Its indicators are regularly used alongside productivity, cost, quality, health and safety in operations and corporate social responsibility reporting. The purpose of this paper is to show an eco-efficiency modelling framework, and its application in the case of an automotive manufacturer. The framework composes, models and analyses resource and production data. Focus on energy, water distributions and material transformations in manufacturing, utility and facility assets are used to analyse eco-efficiency. Resources are examined in respect to three data granularity factors: subdivision, pulse, and magnitude. Models are linked with performance indicators to assess asset eco-efficiency. This work contributes to industrial sustainability literature by introducing a modelling framework that links with data granularity and eco-efficiency indicators

    Phased array-fed antenna configuration study

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    The scope of this contract entails a configuration study for a phased array fed transmit antenna operating in the frequency band of 17.7 to 20.2 GHz. This initial contract provides a basis for understanding the design limitations and advantages of advanced phased array and cluster feeds (both utilizing intergral MMIC modules) illuminating folded reflector optics (both near field and focused types). Design parametric analyses are performed utilizing as constraints the objective secondary performance requirements of the Advanced Communications Technology Satellite (Table 1.0). The output of the study provides design information which serves as a data base for future active phased array fed antenna studies such as detailed designs required to support the development of a ground tested breadboard. In general, this study is significant because it provides the antenna community with an understanding of the basic principles which govern near field phased scanned feed effects on secondary reflector system performance. Although several articles have been written on analysis procedures and results for these systems, the authors of this report have observed phenomenon of near field antenna systems not previously documented. Because the physical justification for the exhibited performance is provided herein, the findings of this study add a new dimension to the available knowledge of the subject matter

    Phased array-fed antenna configuration study: Technology assessment

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    Spacecraft array fed reflector antenna systems were assessed for particular application to a multiple fixed spot beam/multiple scanning spot beam system. Reflector optics systems are reviewed in addition to an investigation of the feasibility of the use of monolithic microwave integrated circuit power amplifiers and phase shifters in each element of the array feed

    Pore-blockade Times for Field-Driven Polymer Translocation

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    We study pore blockade times for a translocating polymer of length NN, driven by a field EE across the pore in three dimensions. The polymer performs Rouse dynamics, i.e., we consider polymer dynamics in the absence of hydrodynamical interactions. We find that the typical time the pore remains blocked during a translocation event scales as N(1+2ν)/(1+ν)/E\sim N^{(1+2\nu)/(1+\nu)}/E, where ν0.588\nu\simeq0.588 is the Flory exponent for the polymer. In line with our previous work, we show that this scaling behaviour stems from the polymer dynamics at the immediate vicinity of the pore -- in particular, the memory effects in the polymer chain tension imbalance across the pore. This result, along with the numerical results by several other groups, violates the lower bound N1+ν/E\sim N^{1+\nu}/E suggested earlier in the literature. We discuss why this lower bound is incorrect and show, based on conservation of energy, that the correct lower bound for the pore-blockade time for field-driven translocation is given by ηN2ν/E\eta N^{2\nu}/E, where η\eta is the viscosity of the medium surrounding the polymer.Comment: 14 pages, 6 figures, slightly shorter than the previous version; to appear in J. Phys.: Cond. Ma

    Singularity theory study of overdetermination in models for L-H transitions

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    Two dynamical models that have been proposed to describe transitions between low and high confinement states (L-H transitions) in confined plasmas are analysed using singularity theory and stability theory. It is shown that the stationary-state bifurcation sets have qualitative properties identical to standard normal forms for the pitchfork and transcritical bifurcations. The analysis yields the codimension of the highest-order singularities, from which we find that the unperturbed systems are overdetermined bifurcation problems and derive appropriate universal unfoldings. Questions of mutual equivalence and the character of the state transitions are addressed.Comment: Latex (Revtex) source + 13 small postscript figures. Revised versio

    The Legacy of ERA, Privatization and the Policy Ratchet

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    This article explores the ways in which the neo-liberal impetus toward the privatization of state schooling signalled in the Education Reform Act 1988 (ERA) has become embedded in the English school system. Four main points are made. First, that ERA itself was of huge strategic rather than substantive importance as far as privatization is concerned. Second, by tracing the lineage of privatization from ERA onwards a 'ratchet' effect of small and incremental policy moves can be identified, which have disseminated, embedded and naturalized privatization within public sector provision. Third, that while privatization has been taken up and taken much further by New Labour than it had been by the Conservatives there are differences between the two sets of governments in the role of privatization in education policy and the role of the state. Fourth, the participation of private providers in the planning and delivery of state services has put the private sector at the very heart of policy. At points the article draws upon interviews conducted with private sector providers. © 2008 Sage Publications
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