This paper proposes a longitudinal protection scheme utilizing empirical wavelet transform(EWT)for a through-type cophase traction direct power supply system,where both sides of a traction network line exhibit a disti...This paper proposes a longitudinal protection scheme utilizing empirical wavelet transform(EWT)for a through-type cophase traction direct power supply system,where both sides of a traction network line exhibit a distinctive boundary structure.This approach capitalizes on the boundary’s capacity to attenuate the high-frequency component of fault signals,resulting in a variation in the high-frequency transient energy ratio when faults occur inside or outside the line.During internal line faults,the high-frequency transient energy at the checkpoints located at both ends surpasses that of its neighboring lines.Conversely,for faults external to the line,the energy is lower compared to adjacent lines.EWT is employed to decompose the collected fault current signals,allowing access to the high-frequency transient energy.The longitudinal protection for the traction network line is established based on disparities between both ends of the traction network line and the high-frequency transient energy on either side of the boundary.Moreover,simulation verification through experimental results demonstrates the effectiveness of the proposed protection scheme across various initial fault angles,distances to faults,and fault transition resistances.展开更多
目的建立以基质外标法定量,通过式净化柱(EMR-Lipid)结合高效液相色谱-串联质谱法(high performance liquid chromatography-tandem mass spectrometry,HPLC-MS/MS)测定生乳中加米霉素残留量的分析方法。方法样品经酸性乙腈提取后,由EMR...目的建立以基质外标法定量,通过式净化柱(EMR-Lipid)结合高效液相色谱-串联质谱法(high performance liquid chromatography-tandem mass spectrometry,HPLC-MS/MS)测定生乳中加米霉素残留量的分析方法。方法样品经酸性乙腈提取后,由EMR-Lipid通过式净化柱净化,通过BEH C18色谱柱进行梯度洗脱,电喷雾正离子多反应模式进行检测,基质外标法定量。结果加米霉素在0.5~20.0 ng/mL质量浓度范围内呈现良好线性关系,线性相关系数大于0.99;检出限(limit of detection,LOD)为0.5μg/kg;定量限(limit of quantification,LOQ)为1.0μg/kg;加米霉素在生乳中表现为基质增强效应,经基质空白曲线校正后,加米霉素在不同添加浓度平均回收率为74.0%~77.0%,测定结果的相对标准偏差(relative standard deviation,RSD)为3.92%~4.57%。结论该方法准确、灵敏、稳定、简单易操作,可以用于生乳中加米霉素残留量快速测定及定量分析,为生乳中加米霉素残留监控提供技术支持。展开更多
基金supported by the National Natural Science Foundation of China(51767012)Curriculum Ideological and Political Connotation Construction Project of Kunming University of Science and Technology(2021KS009)Kunming University of Science and Technology Online Open Course(MOOC)Construction Project(202107).
文摘This paper proposes a longitudinal protection scheme utilizing empirical wavelet transform(EWT)for a through-type cophase traction direct power supply system,where both sides of a traction network line exhibit a distinctive boundary structure.This approach capitalizes on the boundary’s capacity to attenuate the high-frequency component of fault signals,resulting in a variation in the high-frequency transient energy ratio when faults occur inside or outside the line.During internal line faults,the high-frequency transient energy at the checkpoints located at both ends surpasses that of its neighboring lines.Conversely,for faults external to the line,the energy is lower compared to adjacent lines.EWT is employed to decompose the collected fault current signals,allowing access to the high-frequency transient energy.The longitudinal protection for the traction network line is established based on disparities between both ends of the traction network line and the high-frequency transient energy on either side of the boundary.Moreover,simulation verification through experimental results demonstrates the effectiveness of the proposed protection scheme across various initial fault angles,distances to faults,and fault transition resistances.
文摘目的建立以基质外标法定量,通过式净化柱(EMR-Lipid)结合高效液相色谱-串联质谱法(high performance liquid chromatography-tandem mass spectrometry,HPLC-MS/MS)测定生乳中加米霉素残留量的分析方法。方法样品经酸性乙腈提取后,由EMR-Lipid通过式净化柱净化,通过BEH C18色谱柱进行梯度洗脱,电喷雾正离子多反应模式进行检测,基质外标法定量。结果加米霉素在0.5~20.0 ng/mL质量浓度范围内呈现良好线性关系,线性相关系数大于0.99;检出限(limit of detection,LOD)为0.5μg/kg;定量限(limit of quantification,LOQ)为1.0μg/kg;加米霉素在生乳中表现为基质增强效应,经基质空白曲线校正后,加米霉素在不同添加浓度平均回收率为74.0%~77.0%,测定结果的相对标准偏差(relative standard deviation,RSD)为3.92%~4.57%。结论该方法准确、灵敏、稳定、简单易操作,可以用于生乳中加米霉素残留量快速测定及定量分析,为生乳中加米霉素残留监控提供技术支持。
