795 research outputs found

    Simulated hailstone fabrication and use in testing weatherability of structures

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    Equipment fabricates and uses simulated hailstones to test the weatherability of exposed structures. The equipment projects the hailstones at velocities experienced in hailstorms

    Low speed, long term tracking electric drive system has zero backlash

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    Electric drive system provides low speed, long term tracking of targets that move at a sidereal rate. It utilizes eddy-current energized actuators that are free from radio frequency interference generation and a solid state feedback amplifier with provisions for antibacklash biasing

    Reversible motion drive system Patent

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    Drive system for parabolic tracking antenna with reversible motion and minimal backlas

    The influence of transition metal solutes on dislocation core structure and values of Peierls stress and barrier in tungsten

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    Several transition metals were examined to evaluate their potential for improving the ductility of tungsten. The dislocation core structure and Peierls stress and barrier of 1/21/2 screw dislocations in binary tungsten-transition metal alloys (W1x_{1-x}TMx_{x}) were investigated using first principles electronic structure calculations. The periodic quadrupole approach was applied to model the structure of 1/21/2 dislocation. Alloying with transition metals was modeled using the virtual crystal approximation and the applicability of this approach was assessed by calculating the equilibrium lattice parameter and elastic constants of the tungsten alloys. Reasonable agreement was obtained with experimental data and with results obtained from the conventional supercell approach. Increasing the concentration of a transition metal from the VIIIA group, i.e. the elements in columns headed by Fe, Co and Ni, leads to reduction of the CC^\prime elastic constant and increase of elastic anisotropy A=C44/CC_{44}/C^\prime. Alloying W with a group VIIIA transition metal changes the structure of the dislocation core from symmetric to asymmetric, similar to results obtained for W1x_{1-x}Rex_{x} alloys in the earlier work of Romaner {\it et al} (Phys. Rev. Lett. 104, 195503 (2010))\comments{\cite{WRECORE}}. In addition to a change in the core symmetry, the values of the Peierls stress and barrier are reduced. The latter effect could lead to increased ductility in a tungsten-based alloy\comments{\cite{WRECORE}}. Our results demonstrate that alloying with any of the transition metals from the VIIIA group should have similar effect as alloying with Re.Comment: 12 pages, 8 figures, 3 table

    Ultrahigh Surface Area Three-Dimensional Porous Graphitic Carbon from Conjugated Polymeric Molecular Framework

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    Porous graphitic carbon is essential for many applications such as energy storage devices, catalysts, and sorbents. However, current graphitic carbons are limited by low conductivity, low surface area, and ineffective pore structure. Here we report a scalable synthesis of porous graphitic carbons using a conjugated polymeric molecular framework as precursor. The multivalent cross-linker and rigid conjugated framework help to maintain micro- and mesoporous structures, while promoting graphitization during carbonization and chemical activation. The above unique design results in a class of highly graphitic carbons at temperature as low as 800 ??C with record-high surface area (4073 m2 g-1), large pore volume (2.26 cm-3), and hierarchical pore architecture. Such carbons simultaneously exhibit electrical conductivity >3 times more than activated carbons, very high electrochemical activity at high mass loading, and high stability, as demonstrated by supercapacitors and lithium-sulfur batteries with excellent performance. Moreover, the synthesis can be readily tuned to make a broad range of graphitic carbons with desired structures and compositions for many applications.clos

    Relativistic Calculation of two-Electron one-Photon and Hypersatellite Transition Energies for 12Z3012\leq Z\leq30 Elements

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    Energies of two-electron one-photon transitions from initial double K-hole states were computed using the Dirac-Fock model. The transition energies of competing processes, the Kα\alpha hypersatellites, were also computed. The results are compared to experiment and to other theoretical calculations.Comment: accepted versio

    Evaluated displacement and gas production cross-sections for materials irradiated with intermediate energy nucleons

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    International Conference on Nuclear Data for Science and Technology (ND) -- SEP 11-16, 2016 -- Bruges, BELGIUMWOS: 000426429500034Atomic displacement and gas production cross-sections were obtained for a number of materials to calculate radiation damage and gas production rate in nuclear-and fusion reactors, and neutron spallation sources. An advanced atomistic modelling approach was applied for calculations of the number of stable displacements in materials.Fusion for Energy [F4E-GRT-168.01, F4E-GRT-168.02]The work leading to this publication has been funded partially by Fusion for Energy under the Specific Grant Agreements F4E-GRT-168.01 and F4E-GRT-168.02. This publication reflects the views only of the authors, and Fusion for Energy cannot be held responsible for any use which may be made of the information contained therein

    Use of mixed methods designs in substance research: a methodological necessity in Nigeria

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    The utility of mixed methods (qualitative and quantitative) is becoming increasingly accepted in health sciences, but substance studies are yet to substantially benefit from such utilities. While there is a growing number of mixed methods alcohol articles concerning developed countries, developing nations are yet to embrace this method. In the Nigerian context, the importance of mixed methods research is yet to be acknowledged. This article therefore, draws on alcohol studies to argue that mixed methods designs will better equip scholars to understand, explore, describe and explain why alcohol consumption and its related problems are increasing in Nigeria. It argues that as motives for consuming alcohol in contemporary Nigeria are multiple, complex and evolving, mixed method approaches that provide multiple pathways for proffering solutions to problems should be embraced

    A rebellious past : history, theatre and the England riots

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    Alain Badiou has argued that the England riots of 2011, in dialogue with societal upheavals around the world that same year, demonstrated fundamental crises in our governing social, economic and political discourses. Whilst institutional responses to the riots treated them as an aberration, Badiou believes them to be symptomatic of a broader rebirth of ‘history’ – the coalescing of past and present events into a congruent trajectory with powerful implications for the future. Using Badiou’s argument as a starting point, this article considers two theatrical responses to the riots – Nicholas Kent’s premiere of Gillian Slovo’s The Riots at the Tricycle, and Sean Holmes’ revival of Edward Bond’s Saved at the Lyric Hammersmith. By looking at the ways in which the productions sought to historicise the riots, I unpick both their interpretations of these events, and the contributions they were able to make to the urgent and ongoing discussions that the riots have generated.PostprintPeer reviewe
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