A probe test method was employed to detect the friction condition of the interfaces between tools and blank. At the same time a self-developed measurement apparatus to realize the probe test method was also presented....A probe test method was employed to detect the friction condition of the interfaces between tools and blank. At the same time a self-developed measurement apparatus to realize the probe test method was also presented. Based on the analysis of force, a correlative friction model was also given. With the self-developed measurement apparatus,the effects of three kinds of lubricating oils which were in common use during the process of sheet steel drawing were studied. By probing the friction coefficient values of different lubricating oils during the drawing process of the hot-galvanized sheet steel （steel brand： ST07Zn）, we can see that the friction caused by PK oil was the lowest, so the effect of PK oil was the best. Then PK oil was used as the base lubricating oil and some solid additive powers was added into it to make a new type lubrication （named as L oil）.The result of test proved that the new lubricating oil had remarkable effect on the drawing process of hot-galvanized sheet steel.展开更多
Assessing and using tree species （exotic or native） with superior tolerance to environmental stresses （such as drought and high temperature） play an important role in afforestation practices. In the present study,...Assessing and using tree species （exotic or native） with superior tolerance to environmental stresses （such as drought and high temperature） play an important role in afforestation practices. In the present study, stem sap flow characteristics and responses to ambient meteo- rological factors of three tree species, Albizzia kalkora （native）, Azadirachta indica （exotic）, and Acacia auriculaeformis （exotic）, in a dry-hot valley （Yuanmou, Yunnan Province, China） were investigated using thermal dissipation probes. The diurnal dynamics of sap flow in three studied species displayed an obvious circadian rhythm during the wet and dry seasons, with the exception of A. indica during the dry season. The sap flow velocity （SFV） in A. kalkora and A. auriculaeformis was significantly positively correlated with photosynthetically active radiation （PAR）, air temperature, vapour pressure deficit （VPD） and wind speed, but negatively correlated with atmospheric relative humidity over the two seasons. The cross-corre- lation analysis also revealed that the SFV of the three species was significantly correlated with PAR and VPD （P 〈 0.001）. Additionally, stem sap flow lagged behind PAR but ahead of VPD, and the diurnal sap flow was more dependent on PAR than on VPD. However, we found that the dominant climatic factor influencing the stem sap flow differed between daytime and nighttime. PAR was more influential than other meteorological factors during the daytime, while VPD or other factors were more influential overnight. When the nighttime refilling ability of the three tree species was compared, our results suggest that A. indica has higher drought resistance and better for afforestation of the studied region.展开更多
基金This work is by the National Natural Science Foundation of China(No.22203006,No.21927901,No.92261206,No.21627805,No.12174012,No.21673004,No.21821004,No.21674001,and No.21790363)Ministry of Science and Technology of China(a special talent program)and the Beijing City.
文摘A probe test method was employed to detect the friction condition of the interfaces between tools and blank. At the same time a self-developed measurement apparatus to realize the probe test method was also presented. Based on the analysis of force, a correlative friction model was also given. With the self-developed measurement apparatus,the effects of three kinds of lubricating oils which were in common use during the process of sheet steel drawing were studied. By probing the friction coefficient values of different lubricating oils during the drawing process of the hot-galvanized sheet steel （steel brand： ST07Zn）, we can see that the friction caused by PK oil was the lowest, so the effect of PK oil was the best. Then PK oil was used as the base lubricating oil and some solid additive powers was added into it to make a new type lubrication （named as L oil）.The result of test proved that the new lubricating oil had remarkable effect on the drawing process of hot-galvanized sheet steel.
基金funded by Chinese National Science and technology program(2015BAD07B0105)
文摘Assessing and using tree species （exotic or native） with superior tolerance to environmental stresses （such as drought and high temperature） play an important role in afforestation practices. In the present study, stem sap flow characteristics and responses to ambient meteo- rological factors of three tree species, Albizzia kalkora （native）, Azadirachta indica （exotic）, and Acacia auriculaeformis （exotic）, in a dry-hot valley （Yuanmou, Yunnan Province, China） were investigated using thermal dissipation probes. The diurnal dynamics of sap flow in three studied species displayed an obvious circadian rhythm during the wet and dry seasons, with the exception of A. indica during the dry season. The sap flow velocity （SFV） in A. kalkora and A. auriculaeformis was significantly positively correlated with photosynthetically active radiation （PAR）, air temperature, vapour pressure deficit （VPD） and wind speed, but negatively correlated with atmospheric relative humidity over the two seasons. The cross-corre- lation analysis also revealed that the SFV of the three species was significantly correlated with PAR and VPD （P 〈 0.001）. Additionally, stem sap flow lagged behind PAR but ahead of VPD, and the diurnal sap flow was more dependent on PAR than on VPD. However, we found that the dominant climatic factor influencing the stem sap flow differed between daytime and nighttime. PAR was more influential than other meteorological factors during the daytime, while VPD or other factors were more influential overnight. When the nighttime refilling ability of the three tree species was compared, our results suggest that A. indica has higher drought resistance and better for afforestation of the studied region.
