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G. F. Dionne J. F. Fitzgerald T-S. Chang M. M. Litvak H. R. Fetterman 《International Journal of Infrared and Millimeter Waves》1980,1(4):581-595
The intensity and lineshape of the Doppler-broadened 752.033-GHz (211 202) rotational transition of H2O has been studied passively using a high-resolution two-stage heterodyne radiometer with single-sideband system noise temperature of 45,000 K. The purpose of the experiments was to demonstrate the observability at submillimeter wavelengths of a high-altitude rocket plume simulated by a laboratory H2O jet in a vacuum chamber. First-stage mixing was accomplished by means of a GaAs Schottky diode with first local-oscillator power supplied by a CO2-laser pumped formic-acid laser (761.61 GHz), generating and X-band IF signal. Second localoscillator power was provided by a tunable C-band source. One-MHz resolution capability was obtained by means of a 3-GHz waveguide cavity filter with only 9-dB insertion loss. In the H2O jet experiments, the center frequency of the line was determined to within 1 MHz of the previously reported value. A rotational temperature 75 K, a linewidth 5 MHz, and a Doppler shift 3 MHz (from a 45-degree rotation of the flow direction) were measured with the line-of-sight intersecting the jet axis at a distance downstream of 30 nozzle diameters. These absorption data were ogtained against continuum background radiation sources at temperatures of 1175 and 300 K. 相似文献
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This Letter presents the results of a series of measurements of the Newtonian gravitational constant G using the compensated torsion balance developed at the Measurement Standards Laboratory. Since our last published result using the torsion balance in the compensated mode of operation [Meas. Sci. Technol. 10, 439 (1999)]], several improvements have been made to reduce the uncertainty in the final result. The new measurements have used both stainless steel and copper large masses. The values of G for the two sets of masses are in good agreement. After combining all of the measurements we get a value of G=6.673 87(0.000 27) x 10(-11) m3 kg(-1) s(-2). This new value is 5 parts in 10(5) smaller than our previous published values. 相似文献
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Robert W. Fitzgerald 《Finite Fields and Their Applications》2009,15(1):69-81
We determine the possible pairs of invariants of a trace form and construct forms with these invariants. We use this to construct new maximal Artin–Schreier curves. 相似文献
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Liang Zhang Jinghua Teng Soo Jin Chua Eugene A. Fitzgerald 《Applied Physics A: Materials Science & Processing》2011,103(3):827-830
Linearly polarized light from InGaN green light emitting diode grown on (0001) oriented sapphire is demonstrated by using
subwavelength metallic nanogratings. Polarization ratio can reach 7:1 (∼88%), the highest ever reported from a single light
emitting device. We discuss the design and fabrication of this device in detail. 相似文献