26,404 research outputs found

    Shake It Out

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    Molecular dynamics study of the glass transition in confined water

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    A molecular dynamics simulation of SPC/E water confined in a Silica pore is presented. The pore has been constructed to reproduce the average properties of a pore of Vycor glass. Due to the confinement and to the presence of a strong hydrophilic surface, the dynamic behaviour of the liquid appears to be strongly dependent on the hydration level. The approach to the glass transition of confined water is investigated on lowering hydration and on supercooling in the framework of Mode Coupling Theories. At higher hydrations two quite distinct subsets of water molecules are detectable. Those belonging to the first layer close to the substrate suffer a severe slowing down, while the remaining ones display a scenario typical of supercooled liquids approaching the kinetic glass transition.Comment: Talk presented at "International Workshop on Dynamics in Confinement", Grenoble January 2000, to be appear in J. Phys. Franc

    A New NASTRAN Capability for Data Reduction

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    A new module, MODB, for the data reduction of NASTRAN results is described. NASTRAN analysis results can be filtered and sorted for minimum/maximum values and the printed output resulting from large NASTRAN runs can be limited based on a number of available user options. The sorting is done on stresses, forces and vector quantities like displacements, velocity, and acceleration. The module can be accessed via DMAP alters to existing rigid formats, and has been used on a large number of statics and dynamics problems resulting in considerable savings in cost, time, and the amount of printing

    Out for Change: Racial and Economic Justice Issues in Lesbian, Gay, Bisexual and Transgender Communities

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    This research report identifies the range and complexity of issues faced by low-income LGBT people and LGBT people of color, including poverty and economic hardship, homelessness, the criminal justice system, violence and discrimination, and immigrant rights. The report concludes with a series of recommendations for grantmakers to support these issues

    Four New Capabilities in NASTRAN for Dynamic and Aeroelastic Analyses of Rotating Cyclic Structures

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    Static aerothermoelastic design/analysis of axial-flow compressors, modal flutter analysis of axial-flow turbomachines, forced vibration analysis of rotating cyclic structures and modal flutter analysis of advanced turbopropellers with highly swept blades are four new capabilities developed and implemented in NASTRAN Level 17.7. The contents, applicability and usefulness of these capabilities which were developed and documented under the sponsorship of NASA's Lewis Research Center are discussed. Overall flowcharts and selected examples are presented

    Explicit expressions for optical scalars in gravitational lensing from general matter sources

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    We present explicit expressions for the optical scalars and the deection angle in terms of the energymomentum tensor components of matter distributions. Our work generalizes standard references in the literature where normally stringent assumptions are made on the sources.Comment: Talk presented at the Conference I COSMOSUL (2011) (COSMOLOGY AND GRAVITATION IN THE SOUTHERN CONE

    A route to explain water anomalies from results on an aqueous solution of salt

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    In this paper we investigate the possibility to detect the hypothesized liquid-liquid critical point of water in supercooled aqueous solutions of salts. Molecular dynamics computer simulations are conducted on bulk TIP4P water and on an aqueous solution of sodium chloride in TIP4P water, with concentration c = 0.67 mol/kg. The liquid-liquid critical point is found both in the bulk and in the solution. Its position in the thermodynamic plane shifts to higher temperature and lower pressure for the solution. Comparison with available experimental data allowed us to produce the phase diagrams of both bulk water and the aqueous solution as measurable in experiments. Given the position of the liquid-liquid critical point in the solution as obtained from our simulations, the experimental determination of the hypothesized liquid-liquid critical point of water in aqueous solutions of salts appears possible.Comment: 5 pages, 6 figures. Accepted for publication on the Journal of Chemical Physics (2010)

    Evaluation of Safety of Reinforced Concrete Buildings to Earthquakes

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    National Science Foundation Grant GK-3637
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