针对配电网节点电压方均根值(root mean square value,RMS)数据规律性差,难以预测的特点,文中提出了一种将自回归移动平均模型(auto-regressive and moving average model,ARMA)应用到电压RMS值预测中的方法。该方法主要包括数据预处理...针对配电网节点电压方均根值(root mean square value,RMS)数据规律性差,难以预测的特点,文中提出了一种将自回归移动平均模型(auto-regressive and moving average model,ARMA)应用到电压RMS值预测中的方法。该方法主要包括数据预处理、ARMA模型拟合训练、ARMA模型拟合评价、ARMA模型预测应用4个步骤。运用Python编程语言实现该方法,随机选取两条10 k V等级的电压RMS值监测序列进行ARMA模型拟合训练,并利用训练完成后的模型进行预测分析,结果表明,两条预测序列与实际值的方均根误差分别为9.57和5.05,本文所提方法能够对电压RMS值进行较为有效的预测,具有较好的有效性和实用性。展开更多
配电网单相接地故障产生的高频信号可以用于接地故障选线.利用馈线零序电流特征频带(SFB),提出一种连续小波变换(CWT)系数的均方根(Root Mean Square,RMS)值与人工神经网络(ANN)相结合的故障选线方法.通过对各条馈线故障后5ms时零序电...配电网单相接地故障产生的高频信号可以用于接地故障选线.利用馈线零序电流特征频带(SFB),提出一种连续小波变换(CWT)系数的均方根(Root Mean Square,RMS)值与人工神经网络(ANN)相结合的故障选线方法.通过对各条馈线故障后5ms时零序电流进行CWT变换,剔除工频信号,并根据能量和最大原则选出故障特征频带.将各条馈线特征频带上CWT系数的均方根值作为ANN选线的输入样本属性,故障馈线编号作为输出样本属性,构造智能选线网络.该方法不需要提出明确的故障选线判据,利用ANN非线性拟合和记忆功能进行故障选线.大量的实验仿真数据表明,该方法选线结果准确可靠.展开更多
Objective To evaluate the effect of short-term soft contact lens （SCLs） wearing on human ocular aberrations （ HOA ）. Methods This prospective study included 50 eyes of 50 young volunteers wearing SCLs for 1 month....Objective To evaluate the effect of short-term soft contact lens （SCLs） wearing on human ocular aberrations （ HOA ）. Methods This prospective study included 50 eyes of 50 young volunteers wearing SCLs for 1 month. The ocular aberrations were measured by Allegretto Wavefront Analyzer. The root-mean-square （RMS） values of the general （RMSG） , higher-order （RMSH） , first to sixth order （ RMS1 to RMS6） and aberration coefficients were analyzed. Results There were no significant differences in the mean values of RMSG, RMSH, RMS1 to RMS6 （ P 〉 0. 05 ） and changes of absolute values of aberration coefficients between baseline and various visits after SCLs discontinuation. However, at d I after the discontinuation of SCLs, changes in coefficient values of the third-order aberrations （ C6 to C9 ） were slightly higher than others, and C7 was the highest. The increase factors of RMS values were higher at 1 week and lower at the 2 week visit after SCLs discontinuation. The uniformity of dominating type in HOA and the corneal topography form was both about 60% after discontinuation of SCLs. The corneal thickness increased after SCLs wear and gradually decreased to baseline until 1 month discontinuation of SCLs. Conclusion The effect of short-term SCLs wear on human ocular aberrations is slight but profound. A month or more wait should be allowed before the short-term SCLs wearers are scheduled for wavefronted-guided LASIK.展开更多
文摘针对配电网节点电压方均根值(root mean square value,RMS)数据规律性差,难以预测的特点,文中提出了一种将自回归移动平均模型(auto-regressive and moving average model,ARMA)应用到电压RMS值预测中的方法。该方法主要包括数据预处理、ARMA模型拟合训练、ARMA模型拟合评价、ARMA模型预测应用4个步骤。运用Python编程语言实现该方法,随机选取两条10 k V等级的电压RMS值监测序列进行ARMA模型拟合训练,并利用训练完成后的模型进行预测分析,结果表明,两条预测序列与实际值的方均根误差分别为9.57和5.05,本文所提方法能够对电压RMS值进行较为有效的预测,具有较好的有效性和实用性。
文摘配电网单相接地故障产生的高频信号可以用于接地故障选线.利用馈线零序电流特征频带(SFB),提出一种连续小波变换(CWT)系数的均方根(Root Mean Square,RMS)值与人工神经网络(ANN)相结合的故障选线方法.通过对各条馈线故障后5ms时零序电流进行CWT变换,剔除工频信号,并根据能量和最大原则选出故障特征频带.将各条馈线特征频带上CWT系数的均方根值作为ANN选线的输入样本属性,故障馈线编号作为输出样本属性,构造智能选线网络.该方法不需要提出明确的故障选线判据,利用ANN非线性拟合和记忆功能进行故障选线.大量的实验仿真数据表明,该方法选线结果准确可靠.
文摘Objective To evaluate the effect of short-term soft contact lens （SCLs） wearing on human ocular aberrations （ HOA ）. Methods This prospective study included 50 eyes of 50 young volunteers wearing SCLs for 1 month. The ocular aberrations were measured by Allegretto Wavefront Analyzer. The root-mean-square （RMS） values of the general （RMSG） , higher-order （RMSH） , first to sixth order （ RMS1 to RMS6） and aberration coefficients were analyzed. Results There were no significant differences in the mean values of RMSG, RMSH, RMS1 to RMS6 （ P 〉 0. 05 ） and changes of absolute values of aberration coefficients between baseline and various visits after SCLs discontinuation. However, at d I after the discontinuation of SCLs, changes in coefficient values of the third-order aberrations （ C6 to C9 ） were slightly higher than others, and C7 was the highest. The increase factors of RMS values were higher at 1 week and lower at the 2 week visit after SCLs discontinuation. The uniformity of dominating type in HOA and the corneal topography form was both about 60% after discontinuation of SCLs. The corneal thickness increased after SCLs wear and gradually decreased to baseline until 1 month discontinuation of SCLs. Conclusion The effect of short-term SCLs wear on human ocular aberrations is slight but profound. A month or more wait should be allowed before the short-term SCLs wearers are scheduled for wavefronted-guided LASIK.
