Soft-switching techniques are attractive to unity-power-factor AC/DC converter in the view of the size reduction and EMI suppression. A soft-switched boost PFC converter has been studied based on its topology analysis...Soft-switching techniques are attractive to unity-power-factor AC/DC converter in the view of the size reduction and EMI suppression. A soft-switched boost PFC converter has been studied based on its topology analysis, PSIM simulation and circuit experiment. A special limitation of soft-switching techniques has been found in their AC/DC applications.展开更多
Presented in this paper is a three-dimensional plastic limit analysis method of bearing capacity of the deeply-embedded large-diameter cylindrical structure in the cross-anisotmpic soft ground. The most likely failure...Presented in this paper is a three-dimensional plastic limit analysis method of bearing capacity of the deeply-embedded large-diameter cylindrical structure in the cross-anisotmpic soft ground. The most likely failure mechanism is assumed to be of a composite rupture surface which is composed of an individual wedge in the passive zone or two wedges in both active and passive zones near the mudline, depending on the separation or bonding state at the interface between the cylindrical structure and neighboring soils in the active wedge, and a truncated spherical slip surface at the base of the cylinder when the structure tends to overturn around a point located on the symmetry axis of the structure. The cylindrical structure and soil interaction system under consideration is also numerically analyzed by the finite element method by virtue of the general-purpose FEM software ABAQUS, in which the soil is assumed to obey tie Hill＇s criterion of yield. Both the failure mechanism assumed and the plastic limit analysis predictions are validated by numerical computations based on FEM. For the K0-consolidated ground of clays typically with anisotropic undrained strength property, it is indicated through a parametric study that limit analysis without consideration of anisotropy of soil overestimates the lateral ultimate bearing capacity of a deeply-embedded cylindrical structure in soft ground in a certain condition.展开更多
We investigate the soft behavior of the tree-level Rutherford scattering processes mediated via t-channel one-graviton exchange.We consider two types of Rutherford scattering processes:a low-energy massless structurel...We investigate the soft behavior of the tree-level Rutherford scattering processes mediated via t-channel one-graviton exchange.We consider two types of Rutherford scattering processes:a low-energy massless structureless projectile(up to spin-1)hits a static massive composite particle carrying various spins(up to spin-2),and slowly moving light projectile hits a heavy static composite target.The unpolarized cross sections in the first type exhibit universal forms at the first two orders in 1/M expansion,yet differ at the next-to-next-to-leading order,though some terms at this order still remain universal or depend on the target spin in a definite manner.The unpolarized cross sections in the second type are universal at the lowest order in projectile velocity expansion and through all orders in 1/M,independent on the spins of both projectile and target.The universality partially breaks down at relative order-v^(2)/M^(2),albeit some terms at this order still depend on the target spin in a specific manner.展开更多
基金Sponsored by the Scientific Research Foundaltion fbr the Returned Overseas Chinese Scholars,Ministry of Education
文摘Soft-switching techniques are attractive to unity-power-factor AC/DC converter in the view of the size reduction and EMI suppression. A soft-switched boost PFC converter has been studied based on its topology analysis, PSIM simulation and circuit experiment. A special limitation of soft-switching techniques has been found in their AC/DC applications.
基金This project is supported bythe National Natural Science Foundation of China (Grant Nos .50579006 ,50639010 and50179006)
文摘Presented in this paper is a three-dimensional plastic limit analysis method of bearing capacity of the deeply-embedded large-diameter cylindrical structure in the cross-anisotmpic soft ground. The most likely failure mechanism is assumed to be of a composite rupture surface which is composed of an individual wedge in the passive zone or two wedges in both active and passive zones near the mudline, depending on the separation or bonding state at the interface between the cylindrical structure and neighboring soils in the active wedge, and a truncated spherical slip surface at the base of the cylinder when the structure tends to overturn around a point located on the symmetry axis of the structure. The cylindrical structure and soil interaction system under consideration is also numerically analyzed by the finite element method by virtue of the general-purpose FEM software ABAQUS, in which the soil is assumed to obey tie Hill＇s criterion of yield. Both the failure mechanism assumed and the plastic limit analysis predictions are validated by numerical computations based on FEM. For the K0-consolidated ground of clays typically with anisotropic undrained strength property, it is indicated through a parametric study that limit analysis without consideration of anisotropy of soil overestimates the lateral ultimate bearing capacity of a deeply-embedded cylindrical structure in soft ground in a certain condition.
基金supported in part by the National Natural Science Foundation of China(11925506,12475090)supported in part by the US Department of Energy(DE-AC05-06OR23177)under which Jefferson Science Associates,LLC operates Jefferson Lab。
文摘We investigate the soft behavior of the tree-level Rutherford scattering processes mediated via t-channel one-graviton exchange.We consider two types of Rutherford scattering processes:a low-energy massless structureless projectile(up to spin-1)hits a static massive composite particle carrying various spins(up to spin-2),and slowly moving light projectile hits a heavy static composite target.The unpolarized cross sections in the first type exhibit universal forms at the first two orders in 1/M expansion,yet differ at the next-to-next-to-leading order,though some terms at this order still remain universal or depend on the target spin in a definite manner.The unpolarized cross sections in the second type are universal at the lowest order in projectile velocity expansion and through all orders in 1/M,independent on the spins of both projectile and target.The universality partially breaks down at relative order-v^(2)/M^(2),albeit some terms at this order still depend on the target spin in a specific manner.
