Space was once a distant dream for African nations like Senegal.But that is changing fast.Today,space is emerging as a strategic frontier for the continent,with 22 countries including Senegal now operating national sp...Space was once a distant dream for African nations like Senegal.But that is changing fast.Today,space is emerging as a strategic frontier for the continent,with 22 countries including Senegal now operating national space agencies.Senegal launched its own agency,the Senegalese Space Study Agency(ASES),in March 2023.The recent inauguration of the African Space Agency’s headquarters in Cairo,Egypt,marks a new chapter in Africa’s rising ambitions beyond Earth.Tasked with coordinating national programmes,the agency seeks to drive economic and social development through space technologies while promoting scientific cooperation both within Africa and internationally.展开更多
With the expansion of hu-man activities in space and thesteady increase in space debris re-sulting therefrom,the space envi-ronment is constantly deteriorat-ing.The space debris hazard hasalready introduced new safety...With the expansion of hu-man activities in space and thesteady increase in space debris re-sulting therefrom,the space envi-ronment is constantly deteriorat-ing.The space debris hazard hasalready introduced new safety is-sues for consideration by space a-gencies,spacecraft designers,manufacturers,scientists and in-surance underwriters. The problem of the pollutionof the space environment causedby space debris has become agrowing concern within interna-tional astronautical circles and theinternational community as awhole. And the management of thespace environment is a matter forinternational cooperation and展开更多
Rock bolting has firmly used as the coal mine roof reinforcement in underground coal mine. The bolting effect of fully grouted rebar bolt is closely related to the bolt surface profile. This paper provides an experime...Rock bolting has firmly used as the coal mine roof reinforcement in underground coal mine. The bolting effect of fully grouted rebar bolt is closely related to the bolt surface profile. This paper provides an experimental study to confirm that bolt rib internal length has great influence on bolting effect. Pull-out tests were conducted using rebar bolt with different rib spacings of 12, 24, 36 and 48 mm representatively from steel tube and from concrete. Results show that peak load increases 25.3% for bolt with large rib spacing. For pull out using concrete block, the increment of peak load between large and small rib spacing is not significant, but the bolt with large rib spacing has great absorption of deformational energy than small rib spacing bolt. This study provides experimental evidence towards optimum design of rock bolt for understand coal mining industry.展开更多
文摘Space was once a distant dream for African nations like Senegal.But that is changing fast.Today,space is emerging as a strategic frontier for the continent,with 22 countries including Senegal now operating national space agencies.Senegal launched its own agency,the Senegalese Space Study Agency(ASES),in March 2023.The recent inauguration of the African Space Agency’s headquarters in Cairo,Egypt,marks a new chapter in Africa’s rising ambitions beyond Earth.Tasked with coordinating national programmes,the agency seeks to drive economic and social development through space technologies while promoting scientific cooperation both within Africa and internationally.
文摘With the expansion of hu-man activities in space and thesteady increase in space debris re-sulting therefrom,the space envi-ronment is constantly deteriorat-ing.The space debris hazard hasalready introduced new safety is-sues for consideration by space a-gencies,spacecraft designers,manufacturers,scientists and in-surance underwriters. The problem of the pollutionof the space environment causedby space debris has become agrowing concern within interna-tional astronautical circles and theinternational community as awhole. And the management of thespace environment is a matter forinternational cooperation and
基金Financial supports for this work,provided by the Open Projects of Research Center of Coal Resources Safe Mining and Clean Utilization,Liaoning of China (No.LNTU15KF02)
文摘Rock bolting has firmly used as the coal mine roof reinforcement in underground coal mine. The bolting effect of fully grouted rebar bolt is closely related to the bolt surface profile. This paper provides an experimental study to confirm that bolt rib internal length has great influence on bolting effect. Pull-out tests were conducted using rebar bolt with different rib spacings of 12, 24, 36 and 48 mm representatively from steel tube and from concrete. Results show that peak load increases 25.3% for bolt with large rib spacing. For pull out using concrete block, the increment of peak load between large and small rib spacing is not significant, but the bolt with large rib spacing has great absorption of deformational energy than small rib spacing bolt. This study provides experimental evidence towards optimum design of rock bolt for understand coal mining industry.
