High-resolution atomic-beam laser spectroscopy has been performed to study Stark effect of Ba atom. Stark spectra have been observed at various electric fields for Ba highly excited states. The scalar polarizability o...High-resolution atomic-beam laser spectroscopy has been performed to study Stark effect of Ba atom. Stark spectra have been observed at various electric fields for Ba highly excited states. The scalar polarizability of the transition from 6s5d3D2 to 5d6p3F3 at 728.0 nm and the tensor polarizability of the 3F3 level have been determined for the first time, to be αs = -89.8 (12) kHz/(kV/cm)2 and αt = -133.7 (20) kHz/(kV/cm)2, respectively.展开更多
An elusive phenomenon is observed in previous investigations on dynamic fracture that the dynamic fracture toughness （DFT） of high strength metals always increases with the loading rate on the order of TPa.m1/2.s-1....An elusive phenomenon is observed in previous investigations on dynamic fracture that the dynamic fracture toughness （DFT） of high strength metals always increases with the loading rate on the order of TPa.m1/2.s-1. For the purpose of verification, variation of DFT with the loading rate for two high strength steels commonly used in the aviation industry, 30CrMnSiA and 40Cr, is studied in this work. Results of the experiments are compared, which were conducted on the modified split Hopkinson pressure bar （SHPB） apparatus, with striker velocities ranging from 9.2 to 24.1 m/s and a constant value of 16.3 m/s for 30CrMnSiA and 40Cr, respectively. It is observed that for 30CrMnSiA, the crack tip loading rate increases with the increase of the striker velocity, while the fracture initiation time and the DFT simultaneously decrease. However, in the tests of 40Cr, there is also an increasing tendency of DFT, similar to other reports. Through an in-depth investigation on the relationship between the dynamic stress intensity factor （DSIF） and the loading rate, it is concluded that the generally increasing tendency in previous studies could be false, which is induced from a limited striker velocity domain and the errors existing in the experimental and numerical processes. To disclose the real dependency of DFT on the loading rate, experimentsneed to be performed in a comparatively large striker velocity range.展开更多
长期储能(long-duration energy storage,LDES)技术的不断发展成熟为解决新型电力系统季节性供需不平衡问题提供了有效途径。现有研究对LDES技术经济参数的发展情况和不同组合对LDES配置需求和成本效益的影响尚缺乏精细化分析,难以准确...长期储能(long-duration energy storage,LDES)技术的不断发展成熟为解决新型电力系统季节性供需不平衡问题提供了有效途径。现有研究对LDES技术经济参数的发展情况和不同组合对LDES配置需求和成本效益的影响尚缺乏精细化分析,难以准确探究LDES的灵活性潜力。为此,该文分析考虑技术经济性的LDES规划特性,面向新型电力系统建立内嵌年度8760h全景时序运行模拟的多时间尺度储能协调优化规划模型。算例基于我国西北某区域实际数据,评估LDES技术经济参数的不同组合与LDES成本效益水平、优化配置结构和对短期储能替代作用的关系。结果表明,LDES的成本效益受储能容量成本和放电效率的影响最大,在低碳转型发展背景下引入LDES最多可以降低电力系统40%左右的总成本。展开更多
文摘High-resolution atomic-beam laser spectroscopy has been performed to study Stark effect of Ba atom. Stark spectra have been observed at various electric fields for Ba highly excited states. The scalar polarizability of the transition from 6s5d3D2 to 5d6p3F3 at 728.0 nm and the tensor polarizability of the 3F3 level have been determined for the first time, to be αs = -89.8 (12) kHz/(kV/cm)2 and αt = -133.7 (20) kHz/(kV/cm)2, respectively.
基金supported by the 111 Project (B07050)the National Natural Science Foundation of China (10932008)
文摘An elusive phenomenon is observed in previous investigations on dynamic fracture that the dynamic fracture toughness （DFT） of high strength metals always increases with the loading rate on the order of TPa.m1/2.s-1. For the purpose of verification, variation of DFT with the loading rate for two high strength steels commonly used in the aviation industry, 30CrMnSiA and 40Cr, is studied in this work. Results of the experiments are compared, which were conducted on the modified split Hopkinson pressure bar （SHPB） apparatus, with striker velocities ranging from 9.2 to 24.1 m/s and a constant value of 16.3 m/s for 30CrMnSiA and 40Cr, respectively. It is observed that for 30CrMnSiA, the crack tip loading rate increases with the increase of the striker velocity, while the fracture initiation time and the DFT simultaneously decrease. However, in the tests of 40Cr, there is also an increasing tendency of DFT, similar to other reports. Through an in-depth investigation on the relationship between the dynamic stress intensity factor （DSIF） and the loading rate, it is concluded that the generally increasing tendency in previous studies could be false, which is induced from a limited striker velocity domain and the errors existing in the experimental and numerical processes. To disclose the real dependency of DFT on the loading rate, experimentsneed to be performed in a comparatively large striker velocity range.
文摘长期储能(long-duration energy storage,LDES)技术的不断发展成熟为解决新型电力系统季节性供需不平衡问题提供了有效途径。现有研究对LDES技术经济参数的发展情况和不同组合对LDES配置需求和成本效益的影响尚缺乏精细化分析,难以准确探究LDES的灵活性潜力。为此,该文分析考虑技术经济性的LDES规划特性,面向新型电力系统建立内嵌年度8760h全景时序运行模拟的多时间尺度储能协调优化规划模型。算例基于我国西北某区域实际数据,评估LDES技术经济参数的不同组合与LDES成本效益水平、优化配置结构和对短期储能替代作用的关系。结果表明,LDES的成本效益受储能容量成本和放电效率的影响最大,在低碳转型发展背景下引入LDES最多可以降低电力系统40%左右的总成本。
