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基于分数阶聚能带分析的微弱故障特征提取研究 被引量:1
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作者 梅检民 肖云魁 +2 位作者 曾锐利 李枫 任金成 《振动与冲击》 EI CSCD 北大核心 2013年第17期138-144,共7页
提出了一种分数阶聚能带时频累加谱方法,快速实现长数据的时频分析,突出目标分量,用于提取变速器急加速过程微弱故障特征。根据变速器输入轴转速信号及传动比确定分数阶傅里叶变换(Fractional Fourier Transform,FRFT)最佳阶次,对变速... 提出了一种分数阶聚能带时频累加谱方法,快速实现长数据的时频分析,突出目标分量,用于提取变速器急加速过程微弱故障特征。根据变速器输入轴转速信号及传动比确定分数阶傅里叶变换(Fractional Fourier Transform,FRFT)最佳阶次,对变速器急加速过程振动信号进行最佳阶次FRFT,根据FRFT模值谱确定聚能带,计算分数阶聚能带时频累加谱,通过对比多组正常和故障数据的分数阶聚能带时频累加谱结果和阶比谱结果,验证该方法的有效性。试验结果表明:根据转速信号能快速、准确确定FRFT最佳阶次;选取聚能带内的FRFT结果进行时频分析,计算量小,分辨率高,分数阶聚能带时频累加谱具有聚焦和局部放大的特点,能很好地突出目标分量,抑噪噪声,是提取变速器急加速过程信号微弱故障特征的有效方法。 展开更多
关键词 分数阶傅里叶变换 聚能带 时频累加谱 微弱故障
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带壳聚能装药壳体飞散速度的爆炸动力学算法 被引量:3
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作者 贺建平 张可玉 詹发民 《爆破》 CSCD 2002年第2期9-11,共3页
分析了带壳聚能装药的爆轰过程以及与薄壁圆管装药壳体膨胀飞散的相似点 ,运用爆炸动力学理论引入药量系数计算壳体飞散速度 ,计算结果与所引用的实验数据较接近 ,为壳体飞散速度的计算提供了新途径。
关键词 飞散速度 爆炸动力学 聚能装药 薄壁圆管 药量系数 爆轰过程 装药结构
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POLYVINYLIDENE FLUORIDE TRACK MICROFILTER
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作者 赵崇德 P.Vater 《Nuclear Science and Techniques》 SCIE CAS CSCD 1995年第2期91-94,共4页
By the etching of PVDF (polyvinylidene) foils perpendicularly bombarded to their surfaces in advance with heavy ions at UNILAC (GSI Darmstadt,Germany),PVDF track microfilters are successfully manufactured and mostly e... By the etching of PVDF (polyvinylidene) foils perpendicularly bombarded to their surfaces in advance with heavy ions at UNILAC (GSI Darmstadt,Germany),PVDF track microfilters are successfully manufactured and mostly evaluated by means of an optical microscope.The recipes of the elaboration,the properties as well as etching and technical parameters of the microfilters are summarized.The possible applications are also discussed briefly. 展开更多
关键词 PVDF Chemical etching Track microfilter Pore size
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Two-dimensional like conjugated copolymers for high efficiency bulk-heterojunction solar cell application:Band gap and energy level engineering 被引量:5
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作者 DUAN ChunHui WANG ChuanDao +3 位作者 LIU ShengJian HUANG Fei CHOY C.H.Wallace CAO Yong 《Science China Chemistry》 SCIE EI CAS 2011年第4期685-694,共10页
Three two-dimensional like conjugated copolymers PFSDCN,PFSDTA and PFSDCNIO,which consist of alternating fluorene and triphenylamine main chain,and different pendant acceptor groups (malononitrile,1,3-diethtyl-2-thiob... Three two-dimensional like conjugated copolymers PFSDCN,PFSDTA and PFSDCNIO,which consist of alternating fluorene and triphenylamine main chain,and different pendant acceptor groups (malononitrile,1,3-diethtyl-2-thiobarbituric acid and 2-(1,2-dihydro-1-oxoinden-3-ylidene)malononitrile) with thiophene as π-bridge,have been designed,synthesized and characterized.The structure-property relationships of the two-dimensional like conjugated copolymers were systematically investigated.The absorption spectra,band gaps,and energy levels of the polymers were effectively tuned by simply attaching different acceptor groups.As the electron-withdrawing ability of the acceptors increased,the band gaps of the polymers were narrowed from 2.05 to 1.61 eV;meanwhile,the LUMO energy levels of the polymers decreased from -3.27 to -3.75 eV,whereas their relatively deep HOMO energy levels of ~-5.35 eV were preserved.BHJ solar cells were fabricated and characterized by using the three polymers as donor materials and the highest power conversion efficiency of 2.87% was achieved for the device based on PFSDTA:(6,6)-phenyl-C71-butyric acid methyl ester blend. 展开更多
关键词 conjugated polymers two-dimensional like polymers band gaps bulk-heterojunction solar cells
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Synthesis and properties of copolymers based on 5,6-dinitrobenzothiadiazole with low band gap and broad absorption spectra 被引量:1
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作者 WANG Fei LIU YongSheng WAN XiangJian ZHOU JiaoYan CHEN YongSheng 《Science China Chemistry》 SCIE EI CAS 2011年第4期617-624,共8页
One polythiophene derivative PT3T and two low band gap copolymers,PBTT-T3T and PBTT,with different ratios of 5,6-dini-trobenzothiadiazole as the acceptor unit in the polymer backbone have been synthesized by Pd-cataly... One polythiophene derivative PT3T and two low band gap copolymers,PBTT-T3T and PBTT,with different ratios of 5,6-dini-trobenzothiadiazole as the acceptor unit in the polymer backbone have been synthesized by Pd-catalyzed Stille-coupling polymerizations.Thermal stability,X-ray diffraction analyses,UV-vis absorption spectra,photoluminescence spectra and electrochemical properties of the copolymers were investigated.The band gap estimated from UV-vis-NIR spectra of the copolymers films varied from 1.39 to 1.94 eV.Among these copolymers,the films of PBTT-T3T and PBTT,which contain the 5,6-dinitrobenzothiadiazole unit,cover a broad wavelength range in the visible and near-infrared region from 400 to 1000 nm with the maximal peak absorption around 700 nm,which is exactly matched with the maximum in the photon flux of the sun. 展开更多
关键词 COPOLYMER broad absorption low band gap charge transfer
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