782 research outputs found

    Development and fabrication of an advanced liquid cooling garment

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    The elastomeric film fin/tube concept which was developed is a composite of polyurethane film, fine expanded silver mesh, a serpentine pattern polyurethane transport tubing and an integral comfort liner, all bonded via adhesive application and vacuum-bagged for final cure. As demonstrated by thermal analysis, the composite garment material is capable of removing a 293 watt (1000 BTU/hr) metabolic load through a head and torso cooling area of .46 sq m (5 sq ft) with tube spacing of slightly under one inch. A total of 60 test elements, each .15m x .15m (6 in. x 6 in.) were fabricated in support of the liquid cooling garment concept development. In parallel with the fabrication of these elements a continuing series of laboratory tests to support the fabrication techniques was carried out. The elements and supporting tests are described

    On Increasing the Accuracy of MacCormack Schemes for Aeroacoustic Applications

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    Due to their inherent dissipation and stability, the MacCormack scheme and its variants have been widely used in the computation of unsteady flow and acoustic problems. However, these schemes require many points per wavelength in order to propagate waves with a reasonable amount of accuracy. In this work, the linear wave propagation characteristics of MacCormack-type schemes are investigated, and methods for greatly improving their performance are described and demonstrated

    Nonlinear Comparison of High-Order and Optimized Finite-Difference Schemes

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    The effect of reducing the formal order of accuracy of a finite-difference scheme in order to optimize its high-frequency performance is investigated using the I-D nonlinear unsteady inviscid Burgers'equation. It is found that the benefits of optimization do carry over into nonlinear applications. Both explicit and compact schemes are compared to Tam and Webb's explicit 7-point Dispersion Relation Preserving scheme as well as a Spectral-like compact scheme derived following Lele's work. Results are given for the absolute and L2 errors as a function of time

    Evaluation of a High-Accuracy MacCormack-Type Scheme Using Benchmark Problems

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    Due to their inherent dissipation and stability, the MacCormack scheme and its variants have been widely used in the computation of unsteady flow and acoustic problems. However, these schemes require many points per wavelength in order to propagate waves with a reasonable amount of accuracy. In this work, the linear wave propagation characteristics of MacCormack-type schemes are shown by solving several of the CAA Benchmark Problems

    ATP allosterically activates the human 5-lipoxygenase molecular mechanism of arachidonic acid and 5(S)-hydroperoxy-6(E),8(Z),11(Z),14(Z)-eicosatetraenoic acid.

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    5-Lipoxygenase (5-LOX) reacts with arachidonic acid (AA) to first generate 5(S)-hydroperoxy-6(E),8(Z),11(Z),14(Z)-eicosatetraenoic acid [5(S)-HpETE] and then an epoxide from 5(S)-HpETE to form leukotriene A4, from a single polyunsaturated fatty acid. This work investigates the kinetic mechanism of these two processes and the role of ATP in their activation. Specifically, it was determined that epoxidation of 5(S)-HpETE (dehydration of the hydroperoxide) has a rate of substrate capture (Vmax/Km) significantly lower than that of AA hydroperoxidation (oxidation of AA to form the hydroperoxide); however, hyperbolic kinetic parameters for ATP activation indicate a similar activation for AA and 5(S)-HpETE. Solvent isotope effect results for both hydroperoxidation and epoxidation indicate that a specific step in its molecular mechanism is changed, possibly because of a lowering of the dependence of the rate-limiting step on hydrogen atom abstraction and an increase in the dependency on hydrogen bond rearrangement. Therefore, changes in ATP concentration in the cell could affect the production of 5-LOX products, such as leukotrienes and lipoxins, and thus have wide implications for the regulation of cellular inflammation

    Ultra-fast mission analysis routine for Apollo Block 2 environmental control system radiators Final report

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    Computer program for rapid mission analysis of Apollo Block 2 environmental control system radiator

    High-Accuracy Compact MacCormack-Type Schemes for Computational Aeroacoustics

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    Using MacCormack-type methods, a new class of highly accurate compact MacCormack-type schemes is derived which does not require a tridiagonal matrix inversion to obtain the spatial derivatives. Two examples are shown, and results of these schemes for three linear and nonlinear CAA Benchmark Problems are presented

    Reduction of Furan and the Preparation of Tetramethylene Derivatives

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    During the study of the nitrogen heterocyclics, a convenient method of preparing δ-chlorovaleronitrile was desired. The synthesis developed involved the procedure of Gilman and Louisinian for decarboxylation of furoic acid. The furan obtained was reduced in the presence of palladous oxide palladium black giving a 95 per cent yield of tetrahydrofuran which was split with hydrogen chloride yielding 55 per cent of the theoretical tetramethylene chlorohydrin. Treatment of the chlorohydrin with phosphorus tribromide gave a 98 per cent yield of tetramethylene chlorobromide which gave a 52 per cent yield of δ-chlorovalero nitrile when reacted with sodium cyanide. The chemicals required and the operations involved lend themselves to the preparation of appreciable quantities

    Waxy Corn a New Crop

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    When Japan took the Netherland East Indies, we not only lost our main supply of rubber and tin, but also our tapioca starch
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