126,880 research outputs found

    Dynamic Doppler simulator Patent

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    Equipment for testing of ground station ranging equipment and spacecraft transponder

    Improved elastomer for use with oxygen difluoride

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    Method improves resistance of CIS-1,4-poly(butadiene) elastomers to attack by oxygen difluoride at low temperatures by replacing silica reinforcement with less reactive substances. Improved elastomeric compound is utilized in bladders, diaphragms, valves, O-rings and seals

    On the Margulis constant for Kleinian groups, I curvature

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    The Margulis constant for Kleinian groups is the smallest constant cc such that for each discrete group GG and each point xx in the upper half space H3{\bold H}^3, the group generated by the elements in GG which move xx less than distance c is elementary. We take a first step towards determining this constant by proving that if ⟨f,g⟩\langle f,g \rangle is nonelementary and discrete with ff parabolic or elliptic of order n≥3n \geq 3, then every point xx in H3{\bold H}^3 is moved at least distance cc by ff or gg where c=.1829…c=.1829\ldots. This bound is sharp

    Segmented back-up bar Patent

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    Segmented back-up bar for butt welding large tubular structures such as rocket booster bodies or tank

    Extraction of black hole coalescence waveforms from noisy data

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    We describe an independent analysis of LIGO data for black hole coalescence events. Gravitational wave strain waveforms are extracted directly from the data using a filtering method that exploits the observed or expected time-dependent frequency content. Statistical analysis of residual noise, after filtering out spectral peaks (and considering finite bandwidth), shows no evidence of non-Gaussian behaviour. There is also no evidence of anomalous causal correlation between noise signals at the Hanford and Livingston sites. The extracted waveforms are consistent with black hole coalescence template waveforms provided by LIGO. Simulated events, with known signals injected into real noise, are used to determine uncertainties due to residual noise and demonstrate that our results are unbiased. Conceptual and numerical differences between our RMS signal-to-noise ratios (SNRs) and the published matched-filter detection SNRs are discussed.Comment: 15 pages, 11 figures. Version accepted for publicatio

    Communications link for SDS 900 series computers

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    High speed, self-clocking single channel control and data link apparatus interfaces between two computers. This combined system reduces data errors

    B747/JT9D flight loads and their effect on engine running clearances and performance deterioration; BCAC NAIL/P and WA JT9D engine diagnostics programs

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    Flight loads on the 747 propulsion system and resulting JT9D blade to outer airseal running clearances during representative acceptance flight and revenue flight sequences were measured. The resulting rub induced clearance changes, and engine performance changes were then analyzed to validate and refine the JT9D-7A short term performance deterioration model
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