Microstructural evolution and strain hardening behavior of a friction stir welded(FSWed) high-strength7075Al-T651 alloy were evaluated.The nugget zone was observed to consist of fine and equiaxed recrystallized grai...Microstructural evolution and strain hardening behavior of a friction stir welded(FSWed) high-strength7075Al-T651 alloy were evaluated.The nugget zone was observed to consist of fine and equiaxed recrystallized grains with a low dislocation density and free of original precipitates,but containing uniformly distributed dispersoids.The strength,joint efficiency,and ductility of the FSWed joints increased with increasing welding speed.A joint efficiency of *91% was achieved at a welding speed of 400 mm/min and rotational rate of 800 r/min,while the ductility remained basically the same as that of the base metal.There was no obvious strain rate sensitivity observed in both base metal and welded joints.While both the base metal and FSWed joints exhibited stage III and IV hardening characteristics,the hardening capacity,strain hardening exponent,and strain hardening rate all increased after friction stir welding.展开更多
Based on the planning practice in Wuhan after the Urban-Rural Planning Law was implemented in 2008,this paper reviews the evolution of detailed control planning in China,and addresses its main problems and conflicts.T...Based on the planning practice in Wuhan after the Urban-Rural Planning Law was implemented in 2008,this paper reviews the evolution of detailed control planning in China,and addresses its main problems and conflicts.The innovation of the hierarchical planning and administration system is discussed,and the administrative measures for the transition period in which the detailed control plans have not yet been made for all the urban areas is proposed.展开更多
A search for the rare decays W^(+)→D_(s)^(+)γ and Z→D0γis performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13TeV,corresponding to an integrated luminosity...A search for the rare decays W^(+)→D_(s)^(+)γ and Z→D0γis performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13TeV,corresponding to an integrated luminosity of 2.0fb−1.No significant signal is observed for either decay mode and upper limits on their branching fractions are set using W^(+)→D_(s)^(+)γ and Z→μ+μ−decays as normalization channels.The upper limits are 6.5×10^(−4) and 2.1×10^(−3) at 95% confidence level for the W^(+)→D_(s)^(+)γ and Z→D^(0)γ decay modes,respectively.This is the first reported search for the Z→D^(0)γ decay,while the upper limit on the W+→D+sγbranching fraction improves upon the previous best limit.展开更多
基金financially supported by Natural Sciences and Engineering Research Council of Canada (NSERC)Premier’s Research Excellence Award (PREA),NSERC-DAS Award,Canada Foundation for Innovation (CFI)+2 种基金Ryerson Research Chair (RRC) programNational Outstanding Young Scientist Foundation of China (No.50525103)Hundred Talents Program of the Chinese Academy of Sciences
文摘Microstructural evolution and strain hardening behavior of a friction stir welded(FSWed) high-strength7075Al-T651 alloy were evaluated.The nugget zone was observed to consist of fine and equiaxed recrystallized grains with a low dislocation density and free of original precipitates,but containing uniformly distributed dispersoids.The strength,joint efficiency,and ductility of the FSWed joints increased with increasing welding speed.A joint efficiency of *91% was achieved at a welding speed of 400 mm/min and rotational rate of 800 r/min,while the ductility remained basically the same as that of the base metal.There was no obvious strain rate sensitivity observed in both base metal and welded joints.While both the base metal and FSWed joints exhibited stage III and IV hardening characteristics,the hardening capacity,strain hardening exponent,and strain hardening rate all increased after friction stir welding.
文摘Based on the planning practice in Wuhan after the Urban-Rural Planning Law was implemented in 2008,this paper reviews the evolution of detailed control planning in China,and addresses its main problems and conflicts.The innovation of the hierarchical planning and administration system is discussed,and the administrative measures for the transition period in which the detailed control plans have not yet been made for all the urban areas is proposed.
文摘A search for the rare decays W^(+)→D_(s)^(+)γ and Z→D0γis performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13TeV,corresponding to an integrated luminosity of 2.0fb−1.No significant signal is observed for either decay mode and upper limits on their branching fractions are set using W^(+)→D_(s)^(+)γ and Z→μ+μ−decays as normalization channels.The upper limits are 6.5×10^(−4) and 2.1×10^(−3) at 95% confidence level for the W^(+)→D_(s)^(+)γ and Z→D^(0)γ decay modes,respectively.This is the first reported search for the Z→D^(0)γ decay,while the upper limit on the W+→D+sγbranching fraction improves upon the previous best limit.