The railway environmental vibration caused by high-speed railways is harmful to the human health,the structural safety of adjacent buildings,and the normal use of precision instruments.At the same time,it occurs frequ...The railway environmental vibration caused by high-speed railways is harmful to the human health,the structural safety of adjacent buildings,and the normal use of precision instruments.At the same time,it occurs frequently.In this case,the railway environmental vibration has drawn much attention with the rapid development of highspeed railways.Studies in Earthquake Engineering show that a convex topography has a great impact on ground vibrations,however,there is no consideration about the convex topographic effect in the study of the railway environmental vibration when the convex topography is near the roadway.In this paper,the influence of a convex topography on the railway environmental vibration was investigated.Two-dimensional(2D)finite element models consist of subgrade-convex topography and subgrade-flat topography are established using the finite element method.The length and the height of the analysis model are taken as 200 m and 41.3 m,respectively.The external soil of the calculation model is simulated via the artificial boundary.By comparison with measured results,the 2D finite element models were verified to be effective.The convex topographic effect is studied by conducting parameter investigations,such as the bottom width,cross-sectional shape,height-width ratio and the foundation soil properties.Results show that the dimension and cross-section shape of the convex topography and the foundation soil properties have significant effect on the convex topographic effect.展开更多
Polyelectrolyte porous membranes(PPMs)belong to the most interesting classes of materials,because the synergy of tunable pore sizes and charge nature of polyelectrolyte endow them with wide-ranging practical applicati...Polyelectrolyte porous membranes(PPMs)belong to the most interesting classes of materials,because the synergy of tunable pore sizes and charge nature of polyelectrolyte endow them with wide-ranging practical applications.However,owing to the water solu-bility and ionic nature of the polyelectrolytes,traditional polyelectrolytes are difficult to use in scalable preparation of high-quality PPMs through the well-developed industrial methods.Poly(ionic liquid)s(PIL)are a subclass of functional polyelectrolytes bearing ionic liquid groups in their repeating unites,inheriting the advantages of ionic liquids(ILs)and macromolecular architecture features.In recent years,along with rapid development of PIL materials chemistry,considerable and significant developments involving the novel preparation methods,and structure-property-function relationships of PPMs have been made.In this review,we highlight the latest discovery and proceedings of PPMs,particularly the advancements in how to tailor structures and properties of PPMs by ra-tional structure design of PILs.The formation mechanisms of various PPMs were also discussed in detail from the viewpoint of PILs molecular structures.A future perspective of the challenges and promising potential of PPMs is cast on the basis of these achieve-ments.We expect that these analyses and deductions will be useful for the design of useful PPMs and serve as a source of inspira-tion for the design of future multifunctional PPMs.展开更多
The development of strategies for producing welldefined chiral porous membranes for the rapid and efficient enantioseparation of racemic mixtures remains a great challenge.Herein,we introduce an innovative,simple,and ...The development of strategies for producing welldefined chiral porous membranes for the rapid and efficient enantioseparation of racemic mixtures remains a great challenge.Herein,we introduce an innovative,simple,and easily scalable synthetic strategy to manufacture chiral porous polymer membranes(CPPMs)bearing chiral NH groups by crosslinking single-component chiral poly(ionic liquid)s(PILs)with water molecules via hydrogen(H)-bonding.展开更多
基金This work is supported by the National Natural Science Foundation of China(Grant No.51868022)and the National Science Foundation for Young Scientists of China(Grant No.51808219).
文摘The railway environmental vibration caused by high-speed railways is harmful to the human health,the structural safety of adjacent buildings,and the normal use of precision instruments.At the same time,it occurs frequently.In this case,the railway environmental vibration has drawn much attention with the rapid development of highspeed railways.Studies in Earthquake Engineering show that a convex topography has a great impact on ground vibrations,however,there is no consideration about the convex topographic effect in the study of the railway environmental vibration when the convex topography is near the roadway.In this paper,the influence of a convex topography on the railway environmental vibration was investigated.Two-dimensional(2D)finite element models consist of subgrade-convex topography and subgrade-flat topography are established using the finite element method.The length and the height of the analysis model are taken as 200 m and 41.3 m,respectively.The external soil of the calculation model is simulated via the artificial boundary.By comparison with measured results,the 2D finite element models were verified to be effective.The convex topographic effect is studied by conducting parameter investigations,such as the bottom width,cross-sectional shape,height-width ratio and the foundation soil properties.Results show that the dimension and cross-section shape of the convex topography and the foundation soil properties have significant effect on the convex topographic effect.
基金We greatly acknowledge the financial supports by the National Natural Science Foundation of China(Grant No.21875119)the Natural Science Foundation of Tianjin City(Grant Nos.19JCYBJC17500,21JCZDJC00250)the National Programfor Support of Top-notch Young Professionals。
文摘Polyelectrolyte porous membranes(PPMs)belong to the most interesting classes of materials,because the synergy of tunable pore sizes and charge nature of polyelectrolyte endow them with wide-ranging practical applications.However,owing to the water solu-bility and ionic nature of the polyelectrolytes,traditional polyelectrolytes are difficult to use in scalable preparation of high-quality PPMs through the well-developed industrial methods.Poly(ionic liquid)s(PIL)are a subclass of functional polyelectrolytes bearing ionic liquid groups in their repeating unites,inheriting the advantages of ionic liquids(ILs)and macromolecular architecture features.In recent years,along with rapid development of PIL materials chemistry,considerable and significant developments involving the novel preparation methods,and structure-property-function relationships of PPMs have been made.In this review,we highlight the latest discovery and proceedings of PPMs,particularly the advancements in how to tailor structures and properties of PPMs by ra-tional structure design of PILs.The formation mechanisms of various PPMs were also discussed in detail from the viewpoint of PILs molecular structures.A future perspective of the challenges and promising potential of PPMs is cast on the basis of these achieve-ments.We expect that these analyses and deductions will be useful for the design of useful PPMs and serve as a source of inspira-tion for the design of future multifunctional PPMs.
基金supported by the Nankai University,the National Science Foundation of China(grant no.21875119)the Natural Science Foundation of Tianjin(19JCYBJC17500).
文摘The development of strategies for producing welldefined chiral porous membranes for the rapid and efficient enantioseparation of racemic mixtures remains a great challenge.Herein,we introduce an innovative,simple,and easily scalable synthetic strategy to manufacture chiral porous polymer membranes(CPPMs)bearing chiral NH groups by crosslinking single-component chiral poly(ionic liquid)s(PILs)with water molecules via hydrogen(H)-bonding.
