29,240 research outputs found

    Study of cryogenic propellant systems for loading the space shuttle

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    Computer programs were written to model the liquid oxygen loading system for the space shuttle. The programs allow selection of input data through graphic displays which schematically depict the part of the system being modeled. The computed output is also displayed in the form of graphs and printed messages. Any one of six computation options may be selected. The first four of these pertain to thermal stresses, pressure surges, cooldown times, flow rates and pressures during cooldown. Options five and six deal with possible water hammer effects due to closing of valves, steady flow and transient response to changes in operating conditions after cooldown. Procedures are given for operation of the graphic display unit and minicomputer

    Perturbation expansions for a class of singular potentials

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    Harrell's modified perturbation theory [Ann. Phys. 105, 379-406 (1977)] is applied and extended to obtain non-power perturbation expansions for a class of singular Hamiltonians H = -D^2 + x^2 + A/x^2 + lambda/x^alpha, (A\geq 0, alpha > 2), known as generalized spiked harmonic oscillators. The perturbation expansions developed here are valid for small values of the coupling lambda > 0, and they extend the results which Harrell obtained for the spiked harmonic oscillator A = 0. Formulas for the the excited-states are also developed.Comment: 23 page

    An in situ instrument for planar O2 optode measurements at benthic interfaces

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    A new in situ instrument for two‐dimensional mapping of oxygen in coastal sediments is presented. The measuring principle is described, and potential mechanical disturbances, solute and particle smearing associated with the measurements, and calibration routines are evaluated. The first in situ measurements obtained in two different benthic communities are presented. In a shallow photosynthetic sediment (1 m of water depth), an extensive horizontal and temporal variation in the O2 distribution caused by benthic photosynthesis and irrigating fauna was resolved. Repetitive planar optode measurements performed along a transect in central Øresund, Denmark (17 m of water depth) revealed a positive correlation between the apparent O2 penetration depths (OP) measured with a lateral distance <5.0 mm, whereas OP measured with a larger horizontal distance (up to 50 m) were not correlated. Consequently, the OP varied in patches with a characteristic size of 5.0 mm. The instrument described is a powerful new tool for in situ characterization of spatiotemporal variations in O2 distributions within benthic communities. The instrument can be adapted for use at full ocean depths, e.g., on deep‐sea landers or remote operating vehicles

    Finding relevant free-text radiology reports at scale with IBM Watson Content Analytics: a feasibility study in the UK NHS

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    Background. Significant amounts of health data are stored as free-text within clinical reports, letters, discharge summaries and notes. Busy clinicians have limited time to read such large amounts of free-text and are at risk of information overload and consequently missing information vital to patient care. Automatically identifying relevant information at the point of care has the potential to reduce these risks but represents a considerable research challenge. One software solution that has been proposed in industry is the IBM Watson analytics suite which includes rule-based analytics capable of processing large document collections at scale. Results. In this paper we present an overview of IBM Watson Content Analytics and a feasibility study using Content Analytics with a large-scale corpus of clinical free-text reports within a UK National Health Service (NHS) context. We created dictionaries and rules for identifying positive incidence of hydronephrosis and brain metastasis from 5.6m radiology reports and were able to achieve 94% precision, 95% recall and 89% precision, 94% recall respectively on a sample of manually annotated reports. With minor changes for US English we applied the same rule set to an open access corpus of 0.5m radiology reports from a US hospital and achieved 93% precision, 94% recall and 84% precision, 88% recall respectively. Conclusions. We were able to implement IBM Watson within a UK NHS context and demonstrate effective results that could provide clinicians with an automatic safety net which highlights clinically important information within free-text documents. Our results suggest that currently available technologies such as IBM Watson Content Analytics already have the potential to address information overload and improve clinical safety and that solutions developed in one hospital and country may be transportable to different hospitals and countries. Our study was limited to exploring technical aspects of the feasibility of one industry solution and we recognise that healthcare text analytics research is a fast moving field. That said, we believe our study suggests that text analytics is sufficiently advanced to be implemented within industry solutions that can improve clinical safety

    d-Dimensional generalization of the point canonical transformation for a quantum particle with position-dependent mass

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    The d-dimensional generalization of the point canonical transformation for a quantum particle endowed with a position-dependent mass in Schrodinger equation is described. Illustrative examples including; the harmonic oscillator, Coulomb, spiked harmonic, Kratzer, Morse oscillator, Poschl-Teller and Hulthen potentials are used as reference potentials to obtain exact energy eigenvalues and eigenfunctions for target potentials at different position-dependent mass settings.Comment: 14 pages, no figures, to appear in J. Phys. A: Math. Ge

    Towards the development of safe and commercially viable nickel–iron batteries: improvements to Coulombic efficiency at high iron sulphide electrode formulations

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    NiFe batteries are emerging as an important energy storage technology but suffer from a hydrogen-producing side reaction which has safety implications and reduces coulombic efficiency. This manuscript describes a systematic improvement approach for the production of Fe/FeS-based anodes at high concentrations of iron sulphide. Electrodes were made by mixing varying amounts of iron sulphide in such a way that its concentration ranges from between 50 and 100 % (compositions expressed on a PTFE-free basis). Electrode performance was evaluated by cycling our in-house-produced anodes against commercially available nickel electrodes. The results show that anodes produced with larger concentrations outperform their lower concentration counterparts in terms of coulombic efficiency although a slight decrease in the overall cell performance was found when using pure FeS anodes. At high FeS concentrations a hydrogen-producing side reaction has been virtually eliminated resulting in coulombic efficiencies of over 95 %. This has important implications for the safety and commercial development of NiFe batteries

    A situational model development in hospitality retailing : the case of Irish pubs

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    Although importance of situational influences on consumer behaviour has been recognised for some time, little research has been conducted into their effects on hospitality retailing. Over the past decade the Irish theme pub sector has enjoyed extensive growth, which recent studies attribute to the situational components inherent within the environment. This study identities and evaluates the situational components that influence consumers within Irish theme pubs and gauges impact of each of the dimensions of an established situational model on customer behaviour using gender and age cohorts. A three phase, mixed method research design was used and respondents were selected from six Irish theme pubs in Melbourne. The study found that both physical and social situational components have a significant influence in attracting, serving and satisfying the needs of consumers.<br /

    Irish theme pubs : an evaluation of environmental cues

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    A major phenomenon in hospitality retailing in recent years has been the growth in Irish theme pubs. These pubs consist of a collection of both tangible and intangible attributes referred to as environmental cues or atmospherics. Although environmental cues have been found to have a significant influence on consumer behaviour, little research has been conducted into their effects within Irish theme pubs. Using an established research framework, the aims of this study were to identify and evaluate environmental cues within Irish theme pubs and to establish how the dimensions of this framework influenced customers of Irish theme pubs in Melbourne. Qualitative interviews were conducted with customers of six selected Irish theme pubs and with the owners of these establishments. Whilst confirming the impOliance of environmental cues to Irish theme pub customers, the study also provides information that has application for hospitality retailers.<br /
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