In this study, we apply the data envelopment analysis(DEA) model to quantitatively measure the input and output efficiency of 19 urban agglomerations in China from 2011 to 2016. The results show that the input and out...In this study, we apply the data envelopment analysis(DEA) model to quantitatively measure the input and output efficiency of 19 urban agglomerations in China from 2011 to 2016. The results show that the input and output efficiency of urban agglomerations is relatively not high, only a small number of that reach the optimal DEA efficiency. It is clearly revealed that there are the regions from the east that presents the better performance, followed by regions from the central and the west. The peer counts show that Zhusanjiao is taken into account 12 times which shows the importance here of the Zhusanjiao model.Considering the values for radial movements and the slack movements, respective urban agglomeration has their improving orientation towards the capital slack, the labor slack or the land slack. It offers a scientific decision-making of for healthy urbanization and high quality development.展开更多
为了提高通信配电系统中不间断电源(Uninterruptible Power Supply,UPS)输入级的电能质量,引入三相功率因数校正(Power Factor Correction,PFC)技术,优化UPS输入级结构,设计适用于不平衡电网条件的三相PFC拓扑与控制策略,并完成硬件选...为了提高通信配电系统中不间断电源(Uninterruptible Power Supply,UPS)输入级的电能质量,引入三相功率因数校正(Power Factor Correction,PFC)技术,优化UPS输入级结构,设计适用于不平衡电网条件的三相PFC拓扑与控制策略,并完成硬件选型与实验验证。实验结果表明,所提方案可显著提高输入端功率因数,抑制电流谐波,降低总谐波畸变率,使三相信号更加均衡。研究结果对提高UPS系统输入效率、保障电力设备稳定运行具有重要意义。展开更多
Based on 266 strong ground motion records, an attenuation relationship was developed for both absolute and relative input energy spectra. The comparison of the two kinds of input energy spectra constructed from the at...Based on 266 strong ground motion records, an attenuation relationship was developed for both absolute and relative input energy spectra. The comparison of the two kinds of input energy spectra constructed from the attenuation relationship was made in this paper. The results show that there is little difference between the absolute input energy spectra and relative input energy spectra at the periods of 0.5-1.0 s for elastic systems and at the period of 0.5 s for inelastic systems. The absolute input energy spectra are much larger than relative input energy spectra in very short period range but some less than relative input energy spectra in long period range. It is also found that the ductility factor has a significant effect on both absolute and relative input energy spectra. The absolute input energy spectra increase with the increasing of ductility factor in the period range of less than 0.3 s but decrease in the period range of larger than 0.3 s. The absolute input energy spectra for different ductility factor are almost equivalent at the period about 0.3 s, but for relative input energy spectra, the period is about 0.5 s. The effect of ductility on the relative input energy spectra in the short period range is much larger than that on the absolute input energy spectra, especially on the softer site class.展开更多
文摘In this study, we apply the data envelopment analysis(DEA) model to quantitatively measure the input and output efficiency of 19 urban agglomerations in China from 2011 to 2016. The results show that the input and output efficiency of urban agglomerations is relatively not high, only a small number of that reach the optimal DEA efficiency. It is clearly revealed that there are the regions from the east that presents the better performance, followed by regions from the central and the west. The peer counts show that Zhusanjiao is taken into account 12 times which shows the importance here of the Zhusanjiao model.Considering the values for radial movements and the slack movements, respective urban agglomeration has their improving orientation towards the capital slack, the labor slack or the land slack. It offers a scientific decision-making of for healthy urbanization and high quality development.
文摘为了提高通信配电系统中不间断电源(Uninterruptible Power Supply,UPS)输入级的电能质量,引入三相功率因数校正(Power Factor Correction,PFC)技术,优化UPS输入级结构,设计适用于不平衡电网条件的三相PFC拓扑与控制策略,并完成硬件选型与实验验证。实验结果表明,所提方案可显著提高输入端功率因数,抑制电流谐波,降低总谐波畸变率,使三相信号更加均衡。研究结果对提高UPS系统输入效率、保障电力设备稳定运行具有重要意义。
基金Natural Science Foundation of Heilongjiang Province (E0221)Commonweal Foundation of the Ministry of Science and Technology of China (2001DIB20098).
文摘Based on 266 strong ground motion records, an attenuation relationship was developed for both absolute and relative input energy spectra. The comparison of the two kinds of input energy spectra constructed from the attenuation relationship was made in this paper. The results show that there is little difference between the absolute input energy spectra and relative input energy spectra at the periods of 0.5-1.0 s for elastic systems and at the period of 0.5 s for inelastic systems. The absolute input energy spectra are much larger than relative input energy spectra in very short period range but some less than relative input energy spectra in long period range. It is also found that the ductility factor has a significant effect on both absolute and relative input energy spectra. The absolute input energy spectra increase with the increasing of ductility factor in the period range of less than 0.3 s but decrease in the period range of larger than 0.3 s. The absolute input energy spectra for different ductility factor are almost equivalent at the period about 0.3 s, but for relative input energy spectra, the period is about 0.5 s. The effect of ductility on the relative input energy spectra in the short period range is much larger than that on the absolute input energy spectra, especially on the softer site class.
