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基于相关特性船舶辐射噪声DEMON谱信噪比增强算法 被引量:2
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作者 王森 邱家兴 王顺杰 《舰船科学技术》 北大核心 2013年第8期24-27,共4页
基于实测船舶辐射噪声信号的非均匀调制特性,通过时域延时和频域子带2种方式对同一船舶噪声信号进行不同DEMON谱函数的划分。定义不同DEMON谱函数间的平均相关系数和最优DEMON谱函数,提出一种基于不同DEMON谱函数的调制线谱与干扰的统... 基于实测船舶辐射噪声信号的非均匀调制特性,通过时域延时和频域子带2种方式对同一船舶噪声信号进行不同DEMON谱函数的划分。定义不同DEMON谱函数间的平均相关系数和最优DEMON谱函数,提出一种基于不同DEMON谱函数的调制线谱与干扰的统计学相关特性差异来提高所得信号信噪比的算法。实验结果表明,该算法可以提高DEMON谱信噪比,有利于对目标的特征提取和分类识别。 展开更多
关键词 信噪比 非均匀调制 最优谱函数 相关特性
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Theoretical Studies on Electronic Structures and Spectroscopy of Fluorescent Arylamino Fumaronitrile
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作者 Xiao-peng Chen Yu-qi Ding Qi-wen Teng 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 北大核心 2008年第2期105-110,共6页
A new series of fluorescent arylamino fumarinitrile derivatives was designed and optimized using density function theory at the B3LYP/6-31G^* level. Based on the optimized geometries, the electronic, fluorescent and ... A new series of fluorescent arylamino fumarinitrile derivatives was designed and optimized using density function theory at the B3LYP/6-31G^* level. Based on the optimized geometries, the electronic, fluorescent and 13C NMR spectra are calculated with INDO/CIS, CIS-ZINDO TD, and B3LYP/6-31G^* methods, respectively. Starting with the first of the series, the LUMO-HOMO energy gaps of the derivatives become wider and the fluorescent wavelengths and the main peaks in the electronic spectra are blue-shifted owing to the large steric effect of naphthyl rings. On the contrary, the energy gaps of the derivatives turn narrow, and the fluorescent wavelengths and the main peaks in the electronic spectra are red-shifted since hydroxyl groups improve the symmetry and extend the conjugation system. The chemical shifts of sp^2-C on the phenyl rings are moved upfield, while chemical shifts of carbon atoms on the cyano groups and those connected with the cyano groups are changed downfield in the presence of hydroxyl groups. 展开更多
关键词 Arylamino fumaronitrile FLUORESCENCE Energy gap B3LYP/6-31G^*
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