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基于局部语义的网页净化算法
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作者 谢华 刘卫国 《计算机系统应用》 2007年第5期25-28,共4页
网页净化算法的目的是除去影响搜索引擎获取网页主题的噪音。本文提出一种基于局部语义的网页净化算法。算法遍历转化成DOM树后的网页,通过计算相邻节点的相似度,确定局部语义节点范围,然后提取局部语义信息,建立局部语义树模型,最后除... 网页净化算法的目的是除去影响搜索引擎获取网页主题的噪音。本文提出一种基于局部语义的网页净化算法。算法遍历转化成DOM树后的网页,通过计算相邻节点的相似度,确定局部语义节点范围,然后提取局部语义信息,建立局部语义树模型,最后除去与网页主体的相关性低于预定阈值的局部语义节点,达到网页净化的目的。实验表明算法是有效的。 展开更多
关键词 局部语义 网页净化 本地噪音 算法
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Impact of Phase Noise on TDMS Based Calibration for Spaceborne Multi-Beam Antennas 被引量:1
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作者 Yujie Lin Xiangyuan Bu +2 位作者 Shuai Wang Yuan Chai Jianping An 《China Communications》 SCIE CSCD 2018年第3期128-136,共9页
For spaceborne multi-beam antennas(MBAs), time division multiplexed switching(TDMS) based calibration receiver can reduce implementation costs effectively and is very suitable for large-scale applications. However, in... For spaceborne multi-beam antennas(MBAs), time division multiplexed switching(TDMS) based calibration receiver can reduce implementation costs effectively and is very suitable for large-scale applications. However, in practice, random phase noise imposed by noisy local oscillators can cause significant performance degradation in TDMS-based calibration systems. Characterization of phase noise effects is therefore crucial for practical applications. In this paper, we analyze the impact of phase noise on the calibration performance for a MBA system. Specifically, we derive the relationship between the probability of correct amplitude/phase estimation and various practical factors involving the signal-to-noise ratio(SNR), the standard deviation of phase noise, the given tolerance region, and the length of the spreading code. The results provide high efficiency for evaluating the calibration performance of the MBAs based on TDMS, especially for precisely anticipating the impact of phase noise. Finally, the accuracy of the derived results is assessed by simulations in different scenarios. 展开更多
关键词 multi-beam antenna CALIBRATION phase noise time division multiplexed switching
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