An accurate finite element ( FE) model was constructed to examine the hysteretic behavior of double-skin steel-concrete composite box ( DSCB) piers for further understanding the seismic performance of DSCB piers;...An accurate finite element ( FE) model was constructed to examine the hysteretic behavior of double-skin steel-concrete composite box ( DSCB) piers for further understanding the seismic performance of DSCB piers; where the local buckling behavior of steel tubes, the confinement of the in-filled concrete and the interface action between steel tube and in-filled concrete were considered. The accuracy of the proposed FE model was verified by the bidirectional cyclic loading test results. Based on the validated FE model, the effects of some key parameters, such as section width to steel thickness ratio, slenderness ratio, aspect ratio and axial load ratio on the hysteretic behavior of DSCB piers were investigated. Finally, the skeleton curve model of DSCB piers was proposed. The numerical simulation results reveal that the peak strength and elastic stiffness decrease with the increase of the section width to steel thickness ratio. Moreover, the increase of the slenderness ratio may result in a significant reduction in the peak strength and elastic stiffness while the ultimate displacement increases. The proposed skeleton curve model can be taken as a reference for seismic performance analyses of the DSCB piers.展开更多
This paper elaborated on the limitation of authentication test theorem, illustrated the fundamental cause of that limitation through examples, then enhanced authentication test to solve this problem, and also proved t...This paper elaborated on the limitation of authentication test theorem, illustrated the fundamental cause of that limitation through examples, then enhanced authentication test to solve this problem, and also proved the soundness of that improvement with formal method. The enhanced theory can deal with protocols with test component as proper subterm of other regular node' s component under certain conditions, and extend the application scope of authentication test. With enhanced authentication test, the automatic protocol verification tools will be more efficient and convenient.展开更多
Studies on communication strategies (CSs) have been carried out for nearly four decades and have contributed a lot to the development of such fields as applied linguistics and second language acquisition, but they a...Studies on communication strategies (CSs) have been carried out for nearly four decades and have contributed a lot to the development of such fields as applied linguistics and second language acquisition, but they are still inadequate and there remain controversies over certain issues. Thus, more systematic and rigorous studies are needed to check or confirm the findings of some studies and further CS research from newer and broader perspectives. This paper mainly reviews the existing empirical studies from different perspectives: CS classifications and research methods, factors affecting the choices of CSs, teachablity and teaching of CSs, and effectiveness of CSs. It is aimed to provide a clear picture of research on L2 CSs and offer some suggestions for further research.展开更多
基金The National Natural Science Foundation of China(No.51678141,51378112)the Open Fund from the National Engineering Laboratory for Technology of Geological Disaster Prevention in Land Transportation,Southwest Jiaotong University(No.SWJTUGGS-2014001)
文摘An accurate finite element ( FE) model was constructed to examine the hysteretic behavior of double-skin steel-concrete composite box ( DSCB) piers for further understanding the seismic performance of DSCB piers; where the local buckling behavior of steel tubes, the confinement of the in-filled concrete and the interface action between steel tube and in-filled concrete were considered. The accuracy of the proposed FE model was verified by the bidirectional cyclic loading test results. Based on the validated FE model, the effects of some key parameters, such as section width to steel thickness ratio, slenderness ratio, aspect ratio and axial load ratio on the hysteretic behavior of DSCB piers were investigated. Finally, the skeleton curve model of DSCB piers was proposed. The numerical simulation results reveal that the peak strength and elastic stiffness decrease with the increase of the section width to steel thickness ratio. Moreover, the increase of the slenderness ratio may result in a significant reduction in the peak strength and elastic stiffness while the ultimate displacement increases. The proposed skeleton curve model can be taken as a reference for seismic performance analyses of the DSCB piers.
基金the National High Technology Research and Development Programme of China(No.863-104-03-01)
文摘This paper elaborated on the limitation of authentication test theorem, illustrated the fundamental cause of that limitation through examples, then enhanced authentication test to solve this problem, and also proved the soundness of that improvement with formal method. The enhanced theory can deal with protocols with test component as proper subterm of other regular node' s component under certain conditions, and extend the application scope of authentication test. With enhanced authentication test, the automatic protocol verification tools will be more efficient and convenient.
文摘Studies on communication strategies (CSs) have been carried out for nearly four decades and have contributed a lot to the development of such fields as applied linguistics and second language acquisition, but they are still inadequate and there remain controversies over certain issues. Thus, more systematic and rigorous studies are needed to check or confirm the findings of some studies and further CS research from newer and broader perspectives. This paper mainly reviews the existing empirical studies from different perspectives: CS classifications and research methods, factors affecting the choices of CSs, teachablity and teaching of CSs, and effectiveness of CSs. It is aimed to provide a clear picture of research on L2 CSs and offer some suggestions for further research.