62,135 research outputs found

    Considerations in the placement of phase calibration tones

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    In the use of tones to calibrate unwanted instrumental phases for very long baseline interferometry experiments, certain problems exist which are related to the placement of these phase calibrator tones. (1) A bias exists in an analytically generated stopping function used during correlation if its frequency satisfies the following condition; f = (f sub s)x(m)/n, where f sub s = sampling frequency, m = any integer, and n = any odd integer. (2) Due to the quantized representation of sine waves in the stopping function, odd harmonics of the fundamental frequencies are generated. Several mechanisms are available through which these harmonics can cause errors in the residual phase extracted from the recorded tones. (3) When multiple tones are injected into a pass band, intermodulation products can occur. The magnitude of these effects is discussed along with strategies designed to avoid them

    Status of wraparound contact solar cells and arrays

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    Solar cells with wraparound contacts provide the following advantages in array assembly: (1) eliminate the need for discretely formed, damage susceptible series tabs; (2) eliminate the n gap problem by allowing the use of uniform covers over the entire cell surface; (3) allow a higher packing factor by reducing the additional series spacing formly required for forming, and routing the series tab; and (4) allow the cell bonding to the interconnect system to be a single-side function wherein series contacts can be made at the same time parallel contracts are made

    Pacific Basin Communication Study, volume 2

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    Users' meeting summary report, chronology of visits, economic data for forum countries, techniques used in the study, communication choices, existing resources in the Pacific Basin, and warc 79 region 3 rules and regulations were presented in volume 2

    A Hidden Broad-Line Region in the Weak Seyfert 2 Galaxy NGC 788

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    We have detected a broad H alpha emission line in the polarized flux spectrum of the Seyfert 2 galaxy NGC 788, indicating that it contains an obscured Seyfert 1 nucleus. While such features have been observed in ~15 other Seyfert 2s, this example is unusual because it has a higher fraction of galaxy starlight in its spectrum, a lower average measured polarization, and a significantly lower radio luminosity than other hidden Seyfert 1s discovered to date. This demonstrates that polarized broad-line regions can be detected in relatively weak classical Seyfert 2s, and illustrates why well-defined, reasonably complete spectropolarimetric surveys at H alpha are necessary in order to assess whether or not all Seyfert 2s are obscured Seyfert 1s.Comment: 10 pages using (AASTEX) aaspp4.sty and 4 postscript figures. Publications of the Astronomical Society of the Pacific, Research Notes, in pres

    High-power, ultralow-mass solar arrays: FY-77 solar arrays technology readiness assessment report, volume 2

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    Development efforts are reported in detail for: (1) a lightweight solar array system for solar electric propulsion; (2) a high efficiency thin silicon solar cell; (3) conceptual design of 200 W/kg solar arrays; (4) fluorocarbon encapsulation for silicon solar cell array; and (5) technology assessment of concentrator solar arrays

    First Record of \u3ci\u3eOchlerotatus Japonicus\u3c/i\u3e (Diptera: Culicidae) in St. Joseph County, Indiana

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    A single female specimen of Ochlerotatus japonicus (Theobald)(formerly Aedes japonicus), the Asian bush mosquito, was captured in St. Joseph County, IN on 29 July 2004. This is the first report of that species in northern Indiana. Additional specimens were subsequently collected, indicating probable establishment throughout the county
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