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基于复Morlet小波的汽车主减速器故障特征提取 被引量:8
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作者 张志刚 周晓军 宫燃 《农业机械学报》 EI CAS CSCD 北大核心 2008年第11期192-196,共5页
提出了基于复Morlet小波的汽车主减速器故障特征提取方法。针对汽车主减速器故障振动信号的特点,结合复小波变换提供的幅值和相位信息构造了两组适合于机械故障特征提取的组合信息。仿真信号的分析结果表明,采用复小波变换的相位信息及... 提出了基于复Morlet小波的汽车主减速器故障特征提取方法。针对汽车主减速器故障振动信号的特点,结合复小波变换提供的幅值和相位信息构造了两组适合于机械故障特征提取的组合信息。仿真信号的分析结果表明,采用复小波变换的相位信息及所构造的组合信息对信号突变点具有更好的敏感特性,从而可以更好地对信号突变点进行提取和定位。分别采用实小波变换和复小波变换及其组合信息对汽车主减速器故障信号进行分析。分析结果表明,利用所构造的组合信息能够对主减速器故障特征点精确定位;而且只需一尺度小波分解即可得到较好的效果,从而大大减小了故障特征提取的计算量。 展开更多
关键词 汽车 主减速器 故障诊断 特征提取 复Morlet小波 组合信息
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周期聚焦磁场中束晕-混沌的实Morlet小波函数控制(英文) 被引量:4
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作者 余海军 白龙 +2 位作者 翁甲强 罗晓曙 方锦清 《强激光与粒子束》 EI CAS CSCD 北大核心 2008年第6期1017-1021,共5页
基于束晕-混沌的非线性控制策略,对周期性聚焦磁场中初始分布满足K-V分布的粒子束进行模拟研究,提出了控制其束晕-混沌的实Morlet小波函数控制器,并给出具体的实施方案。数值模拟研究表明,在适当的参数条件下,运用这种方法不仅可以消除... 基于束晕-混沌的非线性控制策略,对周期性聚焦磁场中初始分布满足K-V分布的粒子束进行模拟研究,提出了控制其束晕-混沌的实Morlet小波函数控制器,并给出具体的实施方案。数值模拟研究表明,在适当的参数条件下,运用这种方法不仅可以消除束晕及其再生现象,达到对束晕-混沌的有效控制,而且可以控制束流到均匀分布。 展开更多
关键词 强流粒子束 束晕-混沌 周期聚焦磁场 实Morlet小波函数
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The changes of renewable water resources in China during 1956 –2010 被引量:5
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作者 LI YuanYuan CAO JianTing +1 位作者 SHEN FuXin XIA Jun 《Science China Earth Sciences》 SCIE EI CAS 2014年第8期1825-1833,共9页
Water is a critical natural resource upon which all social and economic activities and ecosystem functions depend. With a surprising social and economic development in the past decades, water has become an important c... Water is a critical natural resource upon which all social and economic activities and ecosystem functions depend. With a surprising social and economic development in the past decades, water has become an important constraint for China's sustainable development, and a matter concerning economic security, ecological security and national security of the country. Understanding the changes of water resources is greatly helpful in analyzing the impacts of climatic change, formulating plans for utilization and protection of water resources, and making water resource decisions. Based on China's national water resources assessment, the Mann-Kendall's test, and Morlet wavelet, we analyzed the changing trends and periods of China's renewable water resources during 1956–2010. The results as following:(1) There is no significant change trend of water resources on the countrywide scale during the period 1956–2010, the total water resources show a slight increasing trend, and the national annual average water resources during the period 1991–2010 increased by 1% relative to that of the period 1961–1990.(2) The changes of water resources in different level-I water resource regions vary significantly. Annual average water resources of the Haihe River and Yellow River regions in the northern China decreased 19% and 17% respectively in the past 20 years. Water resource increased in Southern and Northwestern rivers regions, particularly in the Northwest rivers region, with the increasing amplitude by nearly 10% in the past 20 years.(3) The inter-annual variation of national water resource became larger in the past 20 years, as compared with that of the period 1961–1990. The coefficients of water resource variation increased in Northwestern and Southwestern rivers regions, while the inter-annual variation tended to decrease in the Haihe and the Yellow River regions where significant decline of water resources happened.(4) A 14-year quasi-periodicity of the national water resource variation was detected, overlapping with various periodicities of water resources of different level-I water resource regions. Remarkable uniformity exists between the first or secondary primary periodicity of water resource variation in adjacent level-I water resource regions. 展开更多
关键词 water resources ANOMALY variation coefficient Mann-Kendall test morletwavelet
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