A limited-area primitive equation model is used to study the role of the β-effect and a uniform current on tropical cyclone (TC) intensity. It is found that TC intensity is reduced in a non-quiescent environment comp...A limited-area primitive equation model is used to study the role of the β-effect and a uniform current on tropical cyclone (TC) intensity. It is found that TC intensity is reduced in a non-quiescent environment compared with the case of no uniform current. On an f-plane, the rate of intensification of a tropical cyclone is larger than that of the uniform flow. A TC on a β-plane intensifies slower than one on an f-plane. The main physical characteristic that distinguishes the experiments is the asymmetric thermodynamic (including convective) and dynamic structures present when either a uniform flow or β-effect is introduced. But a fairly symmetric TC structure is simulated on an f-plane. The magnitude of the warm core and the associated subsidence are found to be responsible for such simulated intensity changes. On an f-plane, the convection tends to be symmetric, which results in strong upper-level convergence near the center and hence strong forced subsidence and a very warm core. On the other hand, horizontal advection of temperature cancels part of the adiabatic heating and results in less warming of the core, and hence the TC is not as intense. This advective process is due to the tilt of the vortex as a result of the β-effect. A similar situation occurs in the presence of a uniform flow. Thus, the asymmetric horizontal advection of temperature plays an important role in the temperature distribution. Dynamically, the asymmetric angular momentum (AM) flux is very small on an f-plane throughout the troposphere. However, the total AM exports at the upper levels for a TC either on a β-plane or with a uniform flow environment are larger because of an increase of the asymmetric as well as symmetric AM export on the plane at radii >450 km, and hence there is a lesser intensification.展开更多
A scalable and versatile strategy was developed for the fabrication of uniform polymeric microspheres with controllable interconnected porous structures. Uniform water-in-oil-in-water emulsions with linear poly(methyl...A scalable and versatile strategy was developed for the fabrication of uniform polymeric microspheres with controllable interconnected porous structures. Uniform water-in-oil-in-water emulsions with linear poly(methyl methacrylate-glycidyl methacrylate) in the oil phase were generated by two-step premix membrane emulsification and used for constructing the microspheres. During the emulsion solidification process, internal water droplets were packed densely together, forming a thin oil film between the internal and external water phases. After solvent diffusion, the thin film can be ruptured and pores can be templated from the internal water droplets to form interconnected porous structures. Membranes with various pore sizes were obtained. The osmotic pressure and Laplace pressure balance were used to control the porosity and pore size precisely. The proposed method enables the fabrication of functional polymeric microspheres with uniform and controllable porous structures and particle sizes. This improves their performance and broadens the scope of their applications, especially in chromatographic separation.展开更多
The electrochemical energy storage performance is greatly determined by the charge transfer and ion transportation occurring in the electrode materials.Therefore,the enhancement of electric conductivity and ionic mobi...The electrochemical energy storage performance is greatly determined by the charge transfer and ion transportation occurring in the electrode materials.Therefore,the enhancement of electric conductivity and ionic mobility is vital for high-performing and stable metal ion batteries.Here,we report the properties of oxygen vacancies(VO)and carbon co-doped TiO_(2) hollow spheres(HS-TiO_(2))and compared them with fully oxidized white TiO_(2) hollow spheres(W-TiO_(2)).Theoretical calculations and experimental results revealed that the introduction of carbon dopant and VO in anatase TiO_(2) reduced the bandgap and the existence of localized electrons,leading to a lower migration barrier of Li ions that promoted faster ion diffusion kinetics,enabling the HS-TiO_(2) with higher reversibility during the insertion and extraction of Li ions than the W-TiO_(2).This HS-TiO_(2) delivered superior lithium storage properties with a specific discharge capacity of 214.6 mAh g^(-1) for the 100th cycle at 200 mA g^(-1) and 116.3 mAh g^(-1) over 2000 cycles at a high rate of 2 A g^(-1).展开更多
Under strong shocks,long-span spatial-latticed structures may collapse due to dynamic instability or strength failure.The elasto-plastic dynamic behaviors of three spatiallatticed structures,including two double-layer...Under strong shocks,long-span spatial-latticed structures may collapse due to dynamic instability or strength failure.The elasto-plastic dynamic behaviors of three spatiallatticed structures,including two double-layer cylindrical shells and a spheri-cal shell used for the 2008 Olympic Games in Beijing,were quantitatively examined under multi-support excitation(MSE) and uniform support excitation(USE).Numerical analyses described several important parameters such as the peak acceleration and displacement responses at key joints,the number and distribution of plastic elements,and the deformation of the shell at the moment of collapse.Results of the analysis revealed the features and the failure mechanism of the spatial-latticed structures under MSE and USE.In both scenarios,the double-layer reticulated shell collapsed in the "overflow" mode,collapse was govrned by the number of invalid plastic elements rather than the total number of plastic elements,and the collapse of the structure began with damage to certain local regions near the supports.By comparing the numbers and distributions of the plastic members under MSE to those under USE,it was observed that the plastic members spread more sufficiently and the internal forces were more uniform under MSE,especially for lower apparent velocities in soils.Due to the effects of pseudo-static displacement,the stresses in members near supports under MSE were higher than those under USE.These regions are prone to failure during earthquakes and deserve special attention in the seismic design of reticulated structures.展开更多
Let C be a nonempty weakly compact convex subset of a Banach space X, and T : C →C a mapping of asymptotically nonexpansive type. Then there hold the following conclusions: (i) if X has uniform normal structure and l...Let C be a nonempty weakly compact convex subset of a Banach space X, and T : C →C a mapping of asymptotically nonexpansive type. Then there hold the following conclusions: (i) if X has uniform normal structure and limsup |||TjN||| < N(X)~1/(N(X)) , where|||TjN||| is the exact Lipschitz constant of TjN , N is some positive integer, and N(X) is the normal structure coefficient of X, then T has a fixed point; (ii) if X is uniformly convex in every direction and has weak uniform normal structure, then T has a fixed point.展开更多
基金sponsored by the National Natural Science Foundation of China under Grant Nos.49975014,40275018,and 40333025
文摘A limited-area primitive equation model is used to study the role of the β-effect and a uniform current on tropical cyclone (TC) intensity. It is found that TC intensity is reduced in a non-quiescent environment compared with the case of no uniform current. On an f-plane, the rate of intensification of a tropical cyclone is larger than that of the uniform flow. A TC on a β-plane intensifies slower than one on an f-plane. The main physical characteristic that distinguishes the experiments is the asymmetric thermodynamic (including convective) and dynamic structures present when either a uniform flow or β-effect is introduced. But a fairly symmetric TC structure is simulated on an f-plane. The magnitude of the warm core and the associated subsidence are found to be responsible for such simulated intensity changes. On an f-plane, the convection tends to be symmetric, which results in strong upper-level convergence near the center and hence strong forced subsidence and a very warm core. On the other hand, horizontal advection of temperature cancels part of the adiabatic heating and results in less warming of the core, and hence the TC is not as intense. This advective process is due to the tilt of the vortex as a result of the β-effect. A similar situation occurs in the presence of a uniform flow. Thus, the asymmetric horizontal advection of temperature plays an important role in the temperature distribution. Dynamically, the asymmetric angular momentum (AM) flux is very small on an f-plane throughout the troposphere. However, the total AM exports at the upper levels for a TC either on a β-plane or with a uniform flow environment are larger because of an increase of the asymmetric as well as symmetric AM export on the plane at radii >450 km, and hence there is a lesser intensification.
基金the National Natural Science Foundation of China(Nos.21336010 and 81772417)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA16021400).
文摘A scalable and versatile strategy was developed for the fabrication of uniform polymeric microspheres with controllable interconnected porous structures. Uniform water-in-oil-in-water emulsions with linear poly(methyl methacrylate-glycidyl methacrylate) in the oil phase were generated by two-step premix membrane emulsification and used for constructing the microspheres. During the emulsion solidification process, internal water droplets were packed densely together, forming a thin oil film between the internal and external water phases. After solvent diffusion, the thin film can be ruptured and pores can be templated from the internal water droplets to form interconnected porous structures. Membranes with various pore sizes were obtained. The osmotic pressure and Laplace pressure balance were used to control the porosity and pore size precisely. The proposed method enables the fabrication of functional polymeric microspheres with uniform and controllable porous structures and particle sizes. This improves their performance and broadens the scope of their applications, especially in chromatographic separation.
基金supported by the Hefei Institutes of Physical Science,the Chinese Academy of Sciences Director’s Fund(grant nos.YZJJ201902 and YZJJZX202018)the National Natural Science Foundation of China(grant no.52002105)+5 种基金the Key Research and Development Plan Project of Anhui Province(grant no.2022H11020014)the West Light Foundation of the Chinese Academy of Sciences(grant no.XAB2020YW11)the collaborative Innovation Program of Hefei Science Center,CAS(grant no.2022HSC-CIP006)the Natural Science Foundation of Hebei Province(grant no.F2021208014)the Science and Technology Project of Hebei Education Department(grant no.QN2021063)the Science and Technology Research Project for the Colleges and Universities in Hebei Province(grant no.QN2022034).
文摘The electrochemical energy storage performance is greatly determined by the charge transfer and ion transportation occurring in the electrode materials.Therefore,the enhancement of electric conductivity and ionic mobility is vital for high-performing and stable metal ion batteries.Here,we report the properties of oxygen vacancies(VO)and carbon co-doped TiO_(2) hollow spheres(HS-TiO_(2))and compared them with fully oxidized white TiO_(2) hollow spheres(W-TiO_(2)).Theoretical calculations and experimental results revealed that the introduction of carbon dopant and VO in anatase TiO_(2) reduced the bandgap and the existence of localized electrons,leading to a lower migration barrier of Li ions that promoted faster ion diffusion kinetics,enabling the HS-TiO_(2) with higher reversibility during the insertion and extraction of Li ions than the W-TiO_(2).This HS-TiO_(2) delivered superior lithium storage properties with a specific discharge capacity of 214.6 mAh g^(-1) for the 100th cycle at 200 mA g^(-1) and 116.3 mAh g^(-1) over 2000 cycles at a high rate of 2 A g^(-1).
文摘Under strong shocks,long-span spatial-latticed structures may collapse due to dynamic instability or strength failure.The elasto-plastic dynamic behaviors of three spatiallatticed structures,including two double-layer cylindrical shells and a spheri-cal shell used for the 2008 Olympic Games in Beijing,were quantitatively examined under multi-support excitation(MSE) and uniform support excitation(USE).Numerical analyses described several important parameters such as the peak acceleration and displacement responses at key joints,the number and distribution of plastic elements,and the deformation of the shell at the moment of collapse.Results of the analysis revealed the features and the failure mechanism of the spatial-latticed structures under MSE and USE.In both scenarios,the double-layer reticulated shell collapsed in the "overflow" mode,collapse was govrned by the number of invalid plastic elements rather than the total number of plastic elements,and the collapse of the structure began with damage to certain local regions near the supports.By comparing the numbers and distributions of the plastic members under MSE to those under USE,it was observed that the plastic members spread more sufficiently and the internal forces were more uniform under MSE,especially for lower apparent velocities in soils.Due to the effects of pseudo-static displacement,the stresses in members near supports under MSE were higher than those under USE.These regions are prone to failure during earthquakes and deserve special attention in the seismic design of reticulated structures.
基金This research is supported both by the Teaching Research Award Fund tor Outstanding Young Teachers in Higher Education Institutions of MOE, P. R. C., by the Dawn Program Fund in Shanghai.
文摘Let C be a nonempty weakly compact convex subset of a Banach space X, and T : C →C a mapping of asymptotically nonexpansive type. Then there hold the following conclusions: (i) if X has uniform normal structure and limsup |||TjN||| < N(X)~1/(N(X)) , where|||TjN||| is the exact Lipschitz constant of TjN , N is some positive integer, and N(X) is the normal structure coefficient of X, then T has a fixed point; (ii) if X is uniformly convex in every direction and has weak uniform normal structure, then T has a fixed point.
