3,228 research outputs found

    LOX/GOX mechanical impact tester assessment

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    The performances of three existing high pressure oxygen mechanical impact test systems were tested at two different test sites. The systems from one test site were fabricated from the same design drawing, whereas the system tested at the other site was of different design. Energy delivered to the test sample for each test system was evaluated and compared. Results were compared to the reaction rates obtained

    Stylolites in the Burlington Limestone near Kinderhook, Illinois

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    Weil developed stylolites showing a peculiar relationship to chert occur in the Burlington limestone north of Kinderhook, Illinois. Specimens were studied by the preparation of insoluble residues of the limestone and clay cap, and by making thin sections of the chert nodules. Stockdale\u27s conclusion of origin by solution in an indurated rock is ascribed to for the stylolites in question because, (1) crinoid stems are fluted along the sides of prongs the same as the mass of the rock, (2) the suite of minerals occurring in the clay cap\u27\u27 represents nearly a true average of the suites of minerals from the residues above and below the stylolite, (3) the chert in every case examined was prior to the stylolite formation as shown by fluting along the sides and pitting of upper and lower surfaces, and (4) the presence of systems of subsidiary stylolites which crosscut the prongs of the earlier and larger system. The thickness of the clay cap has little relation to the amount of material removed, as it varied up to 75 per cent soluble

    A Robust 43-GHz VCO in CMOS for OC-768 SONET Applications

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    In this paper, we present a 43-GHz LC-VCO in 0.13-/spl mu/m CMOS for use in SONET OC-768 optical networks. A tuned output buffer is used to provide 1.3 V/sub p-p/ (single-ended) into a 90-fF capacitive load as is required when the VCO is used in typical clock and data recovery (CDR) circuits. Phase noise is -90 dBc/Hz at a 1-MHz offset from the carrier; this meets SONET jitter specifications. The design has a tune range of 4.2%. The VCO, including output buffers, consumes 14 mA from a 1-V supply and occupies 0.06 mm/sup 2/ of die area. Modern CMOS process characteristics and the high center frequency of this design mean that the tank loss is not dominated by the integrated inductor, but rather by the tank capacitance. An area-efficient inductor design that does not require any optimization is used

    Preliminary design study of a quiet, high flow fan (QHF) stage

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    Concepts selected to reduce fan generated noise in a turbofan are presented. Near-sonic flow at the fan inlet to reduce upstream propagated noise and the use of long-chord vanes to reduce downstream noise is discussed. The near-sonic condition at the rotor inlet plane was achieved by designing for high specific mass flow and by maintaining the high flow at reduced power by variable stators and variable fan exhaust nozzle. The long-chord vanes reduce response to unsteady flow. The acoustic design showed that long-chord stators would significantly reduce turbofan source noise and that other stator design parameters have no appreciable effect on noise for the spacing and chord length of the turbofan design. Four rig flow paths studied in the aerodynamic preliminary design are discussed. Noise prediction results indicate that a turbofan powered aircraft would be under federal air regulations levels without any acoustic treatment

    Effects of Tillage and Grass Filter Strips on Surface Runoff of Water, Nitrate, Sediment, and Atrazine

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    The contamination of streams and other natural bodies of water through agricultural runoff has become a very important environmental issue. Surface water runoff can contain heavy loads of sediment and/or agricultural chemicals, such as nitrogen and atrazine. Conservation tillage methods with vegetative filter strips downslope from cropped fields help· to combat this problem. Conservation tillage has proven effective in decreasing erosion by decreasing exposure of the soil surface to rainfall. Vegetative filter strips provide an area where sediment and agricultural chemicals from cropland can be deposited before the runoff reaches a body of water
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