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111.
A lunar occultation (LO) technique in the near-infrared (NIR) provides angular resolution down to milliarcseconds for an occulted source, even with ground- based 1 m class telescopes. LO observations are limited to brighter objects because they require a high signal-to-noise ratio (S/N ~40) for proper extraction of angular diameter values. Hence, methods to improve the S/N ratio by reducing noise using Fourier and wavelet transforms have been explored in this study. A sample of 54 NIR LO light curves observed with the IR camera at Mt Abu Observatory has been used. It is seen that both Fourier and wavelet methods have shown an improvement in S/N compared to the original data. However, the application of wavelet transforms causes a slight smoothing of the fringes and results in a higher value for angular diameter. Fourier transforms which reduce discrete noise frequencies do not distort the fringe. The Fourier transform method seems to be effective in improving the S/N, as well as improving the model fit, particularly in the fainter regime of our sample. These methods also provide a better model fit for brighter sources in some cases, though there may not be a significant imorovement in S/N. 相似文献
112.
Yang Zhang Fei Chai Joseph Zhang Yang Ding Min Bao Yunwei Yan Hong Li Wei Yu Liang Chang 《海洋学报(英文版)》2022,41(2):127-138
During the northeast monsoon season, Zhe-Min Coastal Current(ZMCC) travels along the Chinese mainland coast and carries fresh, cold, and eutrophic water. ZMCC is significantly important for the hydrodynamic processes and marine ecosystems along its path. Thus, this bottom-trapped plume deserves to be further discussed in terms of the major driving factor, for which different opinions exist. For this purpose, in this study, a high resolution Semi-implicit Cross-scale Hydroscience Integrated Syste... 相似文献
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The value of the Earth's rotational angular velocity determined from observations is given in the GCRS (geocentric celestial
reference system) defined by Resolution B1 of the 2000 IAU General Assembly. The same quantity derived from dynamical theories
of the Earth's rotation, such as SMART97, is referred to the␣DGRSC (dynamically non-rotating ecliptical reference system).
The relativistic theory of reference systems (RSs) enables unambiguous general-relativity relations between these quantities
to be derived.
Received: 9 November 2000 / Accepted: 9 July 2001 相似文献
118.
卫星遥感结合地面资料对区域表面动量粗糙度的估算 总被引:10,自引:0,他引:10
利用地面湍流观测资料估算了黑河实验区几个典型下垫面的局地地表动量粗糙度,与卫星观测Landsat TM资料相结合得到了由标准化差值植被指数(NDVI)计算地表动量粗糙度的经验关系式,进而估算了实验区夏季和近冬季的地表粗糙度的区域分布,并对所得关系式进行了合理性检验。 相似文献
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