10,207 research outputs found

    High pressure gas storage capacities. Example of a solution using filament windings

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    The use of epoxy resin fiber glass and economic factors affecting the choice of materials for gas storage are discussed. The physical nature of the filament windings are described together with the results obtained. It is demonstrated that a substantial reduction in mass and an enhanced level of safety can be assured at a competitive cost by storing gases in this way

    A kinetic study of the photolysis of tris(2,4-pentanedionato)cobalt(III) and bis(2,4-pentanedionato)cobalt(II) in chloroform

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    Under 254nm irradiation in chloroform, Co(acac)3 (Hacac = 2,4-pentanedione) is converted to Co(acac)2 and then to CoCl2. The metal complex is the primary photoactive species in the photoreduction of Co(acac)3, but the photosubstitution of Co(acac)2 appears to occur primarily through absorption of light by the solvent, followed by a chain reaction in which chlorine atoms displace pentanedionyl radicals. The photosubstitution rate law is complex, and the apparent quantum yield (based on total light absorbed) varies with incident light intensity and Co(acac)2 concentration, reaching values as high as 16 under the conditions of this study. Referred only to the light absorbed by CHCL3, the highest quantum yield measured was 150. An observed partial inverse dependence of the photosubstitution rate on the initial concentration of Co(acac)2 is explained in terms of a mechanism in which the pentanedione product competes with Co(acac)2 for an intermediate

    The Orientation of the Reconnection X-line

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    We propose a criterion for identifying the orientation of the X-line when two regions of plasma with arbitrary densities, temperatures, and magnetic fields undergo reconnection. The X-line points in the direction that maximizes the (suitably-defined) Alfv\'en speed characterizing the reconnection outflow. For many situations a good approximation is that the X-line bisects the angle formed by the magnetic fields

    Ion temperature anisotropy across a magnetotail reconnection jet

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    A significant fraction of the energy released by magnetotail reconnection appears to go into ion heating, but this heating is generally anisotropic. We examine ARTEMIS dual-spacecraft observations of a long-duration magnetotail exhaust generated by anti-parallel reconnection in conjunction with Particle-In-Cell simulations, showing spatial variations in the anisotropy across the outflow far (> 100di) downstream of the X-line. A consistent pattern is found in both the spacecraft data and the simulations: Whilst the total temperature across the exhaust is rather constant, near the boundaries Ti,|| dominates. The plasma is well-above the firehose threshold within patchy spatial regions at |BX| ∈ [0.1, 0.5]B0, suggesting that the drive for the instability is strong and the instability is too weak to relax the anisotropy. At the mid-plane (|BX|0.1 B0), Ti,⊥ > Ti,|| and ions undergo Speiser-like motion despite the large distance from the X-line

    Solar generation and storage of O2 (a 1 delta g)

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    An investigation was performed of the technical steps required to design a solar powered oxygen-iodine laser. Singlet delta oxygen is formed upon transfer of energy from selected photoexcited dye molecules to ground state molecular oxygen and then is concentrated and stored as an endoperoxide by reaction with an aromatic hydrocarbon. The endoperoxide, when heated, releases singlet oxygen in high yield thus providing a regenerable source of laser fuel. Energy transfer from dye molecules to molecular oxygen was investigated. When dye molecules were adsorbed to polymer substrates it was observed that the dye became embedded in the polymer matrix. Porphin dyes were incorporated into films of 1,4-dimethyl-2-poly(vinylnaphthalene), 2PVN. An endoperoxide was formed when porphin-doped 2PVN was exposed to visible radiation. This demonstrates the possibility of generating singlet oxygen using solar energy and concentrating and storing it in one simple step. Transport of energy by exciton migration in polycrystalline dye films was also investigated

    On the 3-D structure and dissipation of reconnection-driven flow-bursts

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    The structure of magnetic reconnection-driven outflows and their dissipation are explored with large-scale, 3-D particle-in-cell (PIC) simulations. Outflow jets resulting from 3-D reconnection with a finite length x-line form fronts as they propagate into the downstream medium. A large pressure increase ahead of this ``reconnection jet front'' (RJF), due to reflected and transmitted ions, slows the front so that its velocity is well below the velocity of the ambient ions in the core of the jet. As a result, the RJF slows and diverts the high-speed flow into the direction perpendicular to the reconnection plane. The consequence is that the RJF acts as a thermalization site for the ion bulk flow and contributes significantly to the dissipation of magnetic energy during reconnection even though the outflow jet is subsonic. This behavior has no counterpart in 2-D reconnection. A simple analytic model predicts the front velocity and the fraction of the ion bulk flow energy that is dissipated
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