5,003 research outputs found

    Enrich: improving integration between an institutional repository and a CRIS at the University of Glasgow

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    This paper provide details of the work and the lessons learned by the JISC funded Enrich project run by the University of Glasgow in the United Kingdom. Enrich provided a clear focus for the integration and enhancement of the University of Glasgow’s repository, Enlighten, with other institutional systems, including our Research System [CRIS] (for funder data) and our Data Vault (for staff records). The Enrich project has demonstrated that partnership between the University Library and the Research Office, in conjunction with researchers, administrators and IT Services is critical to ensuring the successful integration of a repository and a CRIS. Enrich is part of a wider JISC funded programme in the UK: “Information Environment 2009-11” which focuses on the management, discovery and use of information resources. It was completed at the end of March 2010

    Preliminary structural design of composite main rotor blades for minimum weight

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    A methodology is developed to perform minimum weight structural design for composite or metallic main rotor blades subject to aerodynamic performance, material strength, autorotation, and frequency constraints. The constraints and load cases are developed such that the final preliminary rotor design will satisfy U.S. Army military specifications, as well as take advantage of the versatility of composite materials. A minimum weight design is first developed subject to satisfying the aerodynamic performance, strength, and autorotation constraints for all static load cases. The minimum weight design is then dynamically tuned to avoid resonant frequencies occurring at the design rotor speed. With this methodology, three rotor blade designs were developed based on the geometry of the UH-60A Black Hawk titanium-spar rotor blade. The first design is of a single titanium-spar cross section, which is compared with the UH-60A Black Hawk rotor blade. The second and third designs use single and multiple graphite/epoxy-spar cross sections. These are compared with the titanium-spar design to demonstrate weight savings from use of this design methodology in conjunction with advanced composite materials

    Improvements to tilt rotor performance through passive blade twist control

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    A passive blade twist control is presented in which the twist distribution of a tilt rotor blade is elastically changed as a function of rotor speed. The elastic twist deformation is used to achieve two different blade twist distributions corresponding to the two rotor speeds used on conventional tilt rotors in hover and forward flight. By changing the blade twist distribution, the aerodynamic performance can be improved in both modes of flight. The concept presented obtains a change in twist distribution with extension-twist-coupled composite blade structure. This investigation first determines the linear twists which are optimum for each flight mode. Based on the optimum linear twist distributions, three extension-twist-coupled blade designs are developed using coupled-beam and laminate analyses integrated with an optimization analysis. The designs are optimized for maximum twist deformation subject to material strength limitations. The aerodynamic performances of the final designs are determined which show that the passive blade twist control concept is viable, and can enhance conventional tilt rotor performance

    RCUK Open Access Compliance Monitoring Report 2014

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    A preliminary investigation of finite-element modeling for composite rotor blades

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    The results from an initial phase of an in-house study aimed at improving the dynamic and aerodynamic characteristics of composite rotor blades through the use of elastic couplings are presented. Large degree of freedom shell finite element models of an extension twist coupled composite tube were developed and analyzed using MSC/NASTRAN. An analysis employing a simplified beam finite element representation of the specimen with the equivalent engineering stiffness was additionally performed. Results from the shell finite element normal modes and frequency analysis were compared to those obtained experimentally, showing an agreement within 13 percent. There was appreciable degradation in the frequency prediction for the torsional mode, which is elastically coupled. This was due to the absence of off-diagonal coupling terms in the formulation of the equivalent engineering stiffness. Parametric studies of frequency variation due to small changes in ply orientation angle and ply thickness were also performed. Results showed linear frequency variations less than 2 percent per 1 degree variation in the ply orientation angle, and 1 percent per 0.0001 inch variation in the ply thickness

    PRODUCER'S PREFERENCE FOR A COTTON FARMER OWNED RESERVE: AN APPLICATION OF SIMULATION AND STOCHASTIC DOMINANCE

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    The benefits to a typical High Plains cotton farmer from a cotton farmer owned reserve were estimated using a firm-level, income tax and farm policy simulation model. Eighteen farm programs were simulated including twelve variations of a farmer owned reserve using different entry prices and trigger prices. The after-tax net present value distributions for the different farm programs were compared using stochastic dominance. The results indicate that risk averse cotton producers should prefer the 1977 farm program to either a cotton farmer owned reserve or the farm program proposed by Secretary of Agriculture Block.Crop Production/Industries,

    An introduction to the Princeton sailwing windmill

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    Specifically discussed is the sailwing windmill. The aerodynamic characteristics of the sailwing itself are presented in condensed form and its natural application to the wind machine is discussed. Past and present sailwing windmill configurations are shown and their relative merits are compared. A section on a future promising configuration is presented and its compatibility to advanced technology electrical machinery is briefly discussed. Also included is a short bibliography

    On trust and privacy in context-aware systems

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    Recent advances in networking, handheld computing and sensors technologies have led to the emergence of context-aware systems. The vast amounts of personal information collected by such systems has led to growing concerns about the privacy of their users. Users concerned about their private information are likely to refuse participation in such systems. Therefore, it is quite clear that for any context-aware system to be acceptable by the users, mechanisms for controlling access to personal information are a necessity. According to Alan Westin "privacy is the claim of individuals, groups, or institutions to determine for themselves when, how and to what extent information is communicated to others"1. Within this context we can classify users as either information owners or information receivers. It is also acknowledged that information owners are willing to disclose personal information if this disclosure is potentially beneficial. So, the acceptance of any context-aware system depends on the provision of mechanisms for fine-grained control of the disclosure of personal information incorporating an explicit notion of benefit

    Privacy, security, and trust issues in smart environments

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    Recent advances in networking, handheld computing and sensor technologies have driven forward research towards the realisation of Mark Weiser's dream of calm and ubiquitous computing (variously called pervasive computing, ambient computing, active spaces, the disappearing computer or context-aware computing). In turn, this has led to the emergence of smart environments as one significant facet of research in this domain. A smart environment, or space, is a region of the real world that is extensively equipped with sensors, actuators and computing components [1]. In effect the smart space becomes a part of a larger information system: with all actions within the space potentially affecting the underlying computer applications, which may themselves affect the space through the actuators. Such smart environments have tremendous potential within many application areas to improve the utility of a space. Consider the potential offered by a smart environment that prolongs the time an elderly or infirm person can live an independent life or the potential offered by a smart environment that supports vicarious learning

    A FURTHER LOOK AT THE EFFECT OF FEDERAL TAX LAWS ON OPTIMAL MACHINERY REPLACEMENT

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    Self-employment taxes, "effective" marginal tax rates, and discounting schemes which allow for alternative purchase and disposal dates of machinery are incorporated into the traditional optimal replacement interval model. Empirical results indicate that these alterations decrease the optimal replacement intervals by up to three years from those obtained with traditional modeling assumptions. Inclusion of self-employment taxes decreases both the penalty attached to early replacement and the net present value (cost) of tractor ownership.Agricultural and Food Policy,
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