The mechanism of the Richtmyer-Meshkov instability was experimentally studied in a vertical rectangular shock tube. The velocity of the interface driven by the shock wave was measured by a self-designed measurement sy...The mechanism of the Richtmyer-Meshkov instability was experimentally studied in a vertical rectangular shock tube. The velocity of the interface driven by the shock wave was measured by a self-designed measurement system, which consists of semiconductor lasers, signal amplification circuits, digital oscilloscope and computer. Tests were carded out at several shock wave Mach numbers. In addition, the movement of the interface and the variation of the mixed zone width with time were recorded by high-speed photography. The experimental results show that the interface velocity increases with the increase of the Mach number, and the distance of the interface＇s movement and the width of the mixed zone vary with time in a linear relationship.展开更多
Exploring superior electrocatalyst for hydrogen evolution reaction(HER)is an urgent need for hydrogen production based on water splitting.The redistribution of electrons and the increase of active sites through multi-...Exploring superior electrocatalyst for hydrogen evolution reaction(HER)is an urgent need for hydrogen production based on water splitting.The redistribution of electrons and the increase of active sites through multi-interface designing of electrocatalyst are powerful strategies to improve the catalytic efficiency.Herein,a three-phase interface structure of N,P co-doped carbon tube embedded with MoO_(2)/Mo_(2)C(MoO_(2)/Mo_(2)C-CT)was fabricated via a cooperative polymerizing-embedding and pyrolysis strategy.Work function and X-ray photoelectron spectroscopy(XPS)verified that the interfacial charge was quantificationally modulated,achieving an intrinsically enhanced charge transfer by an induced built-in electric field.Theoretical study of density functional theory(DFT)illustrated that triple-interface structure showed a lower energy for H*+H2O*than that of single-interface counterparts.The triple-interface MoO_(2)/Mo_(2)C-CT delivered a lower overpotential of 129 mV at 10 mA·cm^(−2)than that of either single-interface MoO_(2)-CT or Mo_(2)C-CT catalyst.This work may put forward an attractive approach for modulating electronic structure and provide insights into the understanding of triple-interface structure towards HER.展开更多
By means of electron probe(EPMA),scanning electron microscope(SEM),and optical microscope (QM),the diffusion behaviour on the Fe-Cu interface of copper brazed double-wall steel tubes and the microstructure of the diff...By means of electron probe(EPMA),scanning electron microscope(SEM),and optical microscope (QM),the diffusion behaviour on the Fe-Cu interface of copper brazed double-wall steel tubes and the microstructure of the diffusion layer have been investigated.There are three kinds of metallurgical bonds between copper plating layer and steel substrate: (1)the Cu diffusing into steel substrate along grain boundary of ferrite;(2)the Cu diffusion into grain bulk of ferrite: (3)the Fe diffusing into Cu layer.The copper brazed double-wall steel tubes are formed by the combination of the diffusions mentioned above and this is the reason for excellent mechanical and technological properties of the copper brazed double-wall steel tubes.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 10672144)the Natural Science Foundation of Zhejiang Province (Grant No. Y107073)
文摘The mechanism of the Richtmyer-Meshkov instability was experimentally studied in a vertical rectangular shock tube. The velocity of the interface driven by the shock wave was measured by a self-designed measurement system, which consists of semiconductor lasers, signal amplification circuits, digital oscilloscope and computer. Tests were carded out at several shock wave Mach numbers. In addition, the movement of the interface and the variation of the mixed zone width with time were recorded by high-speed photography. The experimental results show that the interface velocity increases with the increase of the Mach number, and the distance of the interface＇s movement and the width of the mixed zone vary with time in a linear relationship.
基金support by the Fundamental Research Funds for the Central Universities(No.22120220058)athe Instrumental Analysis Fund of Tongji University(No.2022GX072).
文摘Exploring superior electrocatalyst for hydrogen evolution reaction(HER)is an urgent need for hydrogen production based on water splitting.The redistribution of electrons and the increase of active sites through multi-interface designing of electrocatalyst are powerful strategies to improve the catalytic efficiency.Herein,a three-phase interface structure of N,P co-doped carbon tube embedded with MoO_(2)/Mo_(2)C(MoO_(2)/Mo_(2)C-CT)was fabricated via a cooperative polymerizing-embedding and pyrolysis strategy.Work function and X-ray photoelectron spectroscopy(XPS)verified that the interfacial charge was quantificationally modulated,achieving an intrinsically enhanced charge transfer by an induced built-in electric field.Theoretical study of density functional theory(DFT)illustrated that triple-interface structure showed a lower energy for H*+H2O*than that of single-interface counterparts.The triple-interface MoO_(2)/Mo_(2)C-CT delivered a lower overpotential of 129 mV at 10 mA·cm^(−2)than that of either single-interface MoO_(2)-CT or Mo_(2)C-CT catalyst.This work may put forward an attractive approach for modulating electronic structure and provide insights into the understanding of triple-interface structure towards HER.
文摘By means of electron probe(EPMA),scanning electron microscope(SEM),and optical microscope (QM),the diffusion behaviour on the Fe-Cu interface of copper brazed double-wall steel tubes and the microstructure of the diffusion layer have been investigated.There are three kinds of metallurgical bonds between copper plating layer and steel substrate: (1)the Cu diffusing into steel substrate along grain boundary of ferrite;(2)the Cu diffusion into grain bulk of ferrite: (3)the Fe diffusing into Cu layer.The copper brazed double-wall steel tubes are formed by the combination of the diffusions mentioned above and this is the reason for excellent mechanical and technological properties of the copper brazed double-wall steel tubes.
