8,061 research outputs found

    Development of an Emulation-simulation Thermal Control Model for Space Station Application

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    Analysis techniques to evaluate the effects of changing thermal loads and the methods utilized to control temperature distributions in the orbital space station are essential. Analysis techniques including a user-friendly computer program, were developed which should prove useful in thermal design and system analysis of the the space station. The program uses a data base and user input to compute costs, sizes, and power requirements for individual components and complete systems. User input consists of selecting mission parameters, selecting thermal acquisition configurations, transport systems and distances, and thermal rejection configurations

    Modeling of transient heat pipe operation

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    The overall goal is to gain a better understanding of the transient behavior of heat pipes operating under both normal and adverse conditions. Normal operation refers to cases where the capillary structure remains fully wetted. Adverse operation occurs when drying, re-wetting, choking, noncontinuum flow, freezing, thawing etc., occur within the heat pipe. The work was redirected towards developing the capability to predict operational behavior of liquid metal heat pipes used for cooling aerodynamic structures. Of particular interest is the startup of such heat pipes from an initially frozen state such as might occur during re-entry of a space vehicle into the Earth's atmosphere or during flight of hypersonic aircraft

    Modeling of Transient Heat Pipe Operation

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    The major goal of this project is to develop mathematical models of heat pipes which can be used to predict transient behavior under normal and adverse conditions. The models and solution techniques are to be formulated so that they can be incorporated into existing NASA structural design codes. The major parameters of interest are heat flux distribution, temperature distribution, working fluid pressure distribution, fluid and containment thermal and mechanical properties and geometry. Normal transient operation is taken to be operating conditions where the capillary structure remains fully wetted. Adverse transient operation occurs when drying, re-wetting, choking, non-continuum flow, thawing, freezing, etc., occur in the internal heat pipe working fluid

    Uranium distribution as a proxy for basin-scale fluid flow in distributive fluvial systems

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    This work was supported by the Fluvial Systems Research Group sponsors BG Group, BP, Chevron, ConocoPhilips, and Total. We thank reviews from Martin Stokes, an anonymous reviewer and Editor Stuart Jones.Peer reviewedPostprin

    The Mass Assembly of Fossil Groups of Galaxies in the Millennium Simulation

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    The evolution of present-day fossil galaxy groups is studied in the Millennium Simulation. Using the corresponding Millennium gas simulation and semi-analytic galaxy catalogues, we select fossil groups at redshift zero according to the conventional observational criteria, and trace the haloes corresponding to these groups backwards in time, extracting the associated dark matter, gas and galaxy properties. The space density of the fossils from this study is remarkably close to the observed estimates and various possibilities for the remaining discrepancy are discussed. The fraction of X-ray bright systems which are fossils appears to be in reasonable agreement with observation, and the simulations predict that fossil systems will be found in significant numbers (3-4% of the population) even in quite rich clusters. We find that fossils assemble a higher fraction of their mass at high redshift, compared to non-fossil groups, with the ratio of the currently assembled halo mass to final mass, at any epoch, being about 10 to 20% higher for fossils. This supports the paradigm whereby fossils represent undisturbed, early-forming systems in which large galaxies have merged to form a single dominant elliptical.Comment: 11 pages, 8 figures, submitted to MNRA

    Feasibility analysis of reciprocating magnetic heat pumps

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    The conceptual design selected for detailed system analysis and optimization is the reciprocating gadolinium core in a regenerative fluid column within the bore of a superconducting magnet. The thermodynamic properties of gadolinium are given. A computerized literature search for relevant papers was conducted and is being analyzed. Contact was made with suppliers of superconducting magnets and accessories, magnetic materials, and various types of hardware. A description of the model for the thermal analysis of the core and regenerator fluids is included

    Perceptions of New Member Academic Engagement: A Mixed Methods Case Study

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    A mixed methods case study was conducted to triangulate a comprehensive assessment of the perceptions of fraternity/sorority life from three different stakeholders on a liberal arts campus. Three electronic surveys were sent to selected groups that asked respondents to provide perceptions of the academic engagement of affiliated students on the campus. In addition, affiliated studentā€™s grade point averages were monitored across three semesters to determine if there was a marked change in academic performance while going through the new member education process. Results showed that new member academic performance was similar across the semester prior to, during, and after the new member experience. Survey results showed differences in perception of affiliated studentsā€™ academic engagement by group surveyed, and provided sources of common interest to promote greater understanding between stakeholder groups

    Moving Forward 21st Century Pathways to Strengthen the Ocean Science Workforce Through Graduate Education and Professional Development

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    The scope of emerging national and international ocean-related issues facing society demands that we develop broad perspectives on graduate education and training in the ocean sciences. A multifaceted ocean workforce and new kinds of intellectual partnerships are needed to address ocean science research priorities, strengthen our understanding of coupled human-natural ocean systems, engage and inform public policy and management decision making, and increase ocean literacy. Alumni from graduate programs in ocean sciences are following diverse career paths in academia, government, nongovernmental organizations, and industry, and thus can inform us about the diverse skills needed to succeed. The ocean science academic community should build on its current strengths (e.g., multidisciplinary and multi-institutional research and education, international partnerships), and capitalize on what some might view as limitations (e.g., remote, yet inviting, coastal campuses, diversity of ocean science programs), to become an incubator of innovation that will advance the field and strengthen graduate education and training. Partnerships within and among institutions with ocean-related programs, and with professional societies, employers, and others, can help us provide cutting-edge, relevant academic options, facilitate professional development, and proactively position graduates for career paths that reflect and address important societal needs
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