The double degrees-of-freedom（DOFs）parallel model is adopted to analyze static vertical human-induced vibration with the finite element analysis（FEA）method.In the first-order symmetric vibration mode,the periods o...The double degrees-of-freedom（DOFs）parallel model is adopted to analyze static vertical human-induced vibration with the finite element analysis（FEA）method.In the first-order symmetric vibration mode,the periods of the spring-mass model gradually decrease with the increase in K1 and K2,but they are always greater than the period of the add-on mass model.Meanwhile,the periods of the spring-mass model decrease with the decrease in m1 and m2,but they are always greater than the period of the hollow bridge model.Since the human＇s two degrees-of-freedom vibrate in the same direction as that of the bridge mid-span,the existence of human＇s rigidity leads to the reduction in the rigidity of the spring-mass model.In the second-order symmetric vibration mode,the changes of rigidity K2 and mass m2 result in the disappearance or occurrence of some vibration modes.It can be concluded that compared with the spring-mass model,the results of the add-on mass model lean to lack of safety to the structure;besides,the DOF with a smaller ratio of mass to rigidity plays the chief role in the vibration of the structure.展开更多
In this paper we propose a two-layer emergent model for scalable swarm system. The first layer describes the indi-vidual flocking behavior to the local goal position (the center of minimal circumcircle decided by the ...In this paper we propose a two-layer emergent model for scalable swarm system. The first layer describes the indi-vidual flocking behavior to the local goal position (the center of minimal circumcircle decided by the neighbors in the positive visual set of individuals) resulting from the individual motion to one or two farthest neighbors in its positive visual set; the second layer describes the emergent aggregating swarm behavior resulting from the individual motion to its local goal position. The scale of the swarm will not be limited because only local individual information is used for modelling in the two-layer topology. We study the stability properties of the swarm emergent behavior based on Lyapunov stability theory. Simulations showed that the swarm system can converge to goal regions while maintaining cohesiveness.展开更多
We study a system consisting of two identical non-interacting single-mode cavity fields coupled to a common vacuum environment and provide general, explicit, and exact solutions to its master equation by means of the ...We study a system consisting of two identical non-interacting single-mode cavity fields coupled to a common vacuum environment and provide general, explicit, and exact solutions to its master equation by means of the characteristic function method. We analyze the entanglement dynamics of two-mode squeezed thermal state in this model and show that its entanglement dynamics is strongly determined by the two-mode squeezing parameter and the purity. In particular, we find that two-mode squeezed thermal state with the squeezing parameter r ≤ -（1/2） In √u is extremely fragile and almost does not survive in a common vacuum environment. We investigate the time evolution of nonlocality for two-mode squeezed thermal state in such an environment. It is found that the evolved state loses its nonlocality in the beginning of the evolution, but after a time, the revival of nonlocality can occur.展开更多
The exact solutions of the general nonlinear dynamic system in a new double-chain model of DNA are studied by using both the Conte's Painlevé truncation expansion and the Pickering's truncation expansion....The exact solutions of the general nonlinear dynamic system in a new double-chain model of DNA are studied by using both the Conte's Painlevé truncation expansion and the Pickering's truncation expansion. The symmetric kink-kink shape excitations can be found in both the Conte's truncation expansion and the Pickering's truncation expansion. Three types of new localized excitations, the asymmetric kink-kink excitations, the soliton-kink excitation, and the kink-soliton excitations, are found by using the Pickering's nonstandard truncation expansion.展开更多
Flow behavior of gas and particles in conical spouted beds is experimentally studied and simulated using the twofluid gas-solid model with the kinetic theory of granular flow.The bed pressure drop and fountain height ...Flow behavior of gas and particles in conical spouted beds is experimentally studied and simulated using the twofluid gas-solid model with the kinetic theory of granular flow.The bed pressure drop and fountain height are measured in a conical spouted bed of 100 mm I.D.at different gas velocities.The simulation results are compared with measurements of bed pressure drop and fountain height.The comparison shows that the drag coefficient model used in cylindrical beds under-predicted bed pressure drop and fountain height in conical spouted beds due to the partial weight of particles supported by the inclined side walls.It is found that the numerical results using the drag coefficient model proposed based on the conical spouted bed in this study are in good agreement with experimental data.The present study provides a useful basis for further works on the CFD simulation of conical spouted bed.展开更多
Presently developed two-phase turbulence models under-predict the gas turbulent fluctuation, because their turbulence modification models cannot fully reflect the effect of particles. In this paper, a two-time-scale d...Presently developed two-phase turbulence models under-predict the gas turbulent fluctuation, because their turbulence modification models cannot fully reflect the effect of particles. In this paper, a two-time-scale dissipation model of turbulence modification, developed for the two-phase velocity correlation and for the dissipation rate of gas turbulent kinetic energy, is proposed and used to simulate sudden-expansion and swirling gas-particle flows. The proposed two-time scale model gives better results than the single-time scale model. Besides, a gas turbulence augmentation model accounting for the f＇mite-size particle wake effect in the gas Reynolds stress equation is proposed. The proposed turbulence modification models are used to simulate two-phase pipe flows. It can properly predict both turbulence reduction and turbulence enhancement for a certain size of particles observed in experiments.展开更多
AIM: To evaluate the shortand long-term outcomes of bilateral liver resection for bilateral intrahepatic stones. METHODS: We reviewed retrospectively 101 consecutive patients with bilateral intrahepatic stones who und...AIM: To evaluate the shortand long-term outcomes of bilateral liver resection for bilateral intrahepatic stones. METHODS: We reviewed retrospectively 101 consecutive patients with bilateral intrahepatic stones who underwent bilateral liver resection in the past 10 years. The shortand long-term outcomes of the patients were analyzed. The Cox proportional hazards model was used to identify the risk factors related to stone recurrence. RESULTS: There was no surgical mortality in this group of patients. The surgical morbidity was 28.7%. Stone clearance rate after hepatectomy was 84.2% and final clearance rate was 95.0% following postoperative choledochoscopic lithotripsy. The stone recurrence rate was 7.9% and the occurrence of postoperative cholangitis was 6.5% in a median follow-up period of 54 mo. The Cox proportional hazards model indicated that liver resection range, less than the range of stone distribution (P = 0.015, OR = 2.152) was an independent risk factor linked to stone recurrence. CONCLUSION: Bilateral liver resection is safe and its shortand long-term outcomes are satisfactory for bilateral intrahepatic stones.展开更多
文摘The double degrees-of-freedom（DOFs）parallel model is adopted to analyze static vertical human-induced vibration with the finite element analysis（FEA）method.In the first-order symmetric vibration mode,the periods of the spring-mass model gradually decrease with the increase in K1 and K2,but they are always greater than the period of the add-on mass model.Meanwhile,the periods of the spring-mass model decrease with the decrease in m1 and m2,but they are always greater than the period of the hollow bridge model.Since the human＇s two degrees-of-freedom vibrate in the same direction as that of the bridge mid-span,the existence of human＇s rigidity leads to the reduction in the rigidity of the spring-mass model.In the second-order symmetric vibration mode,the changes of rigidity K2 and mass m2 result in the disappearance or occurrence of some vibration modes.It can be concluded that compared with the spring-mass model,the results of the add-on mass model lean to lack of safety to the structure;besides,the DOF with a smaller ratio of mass to rigidity plays the chief role in the vibration of the structure.
基金Project (No. 60574088) supported by the National Natural ScienceFoundation of China
文摘In this paper we propose a two-layer emergent model for scalable swarm system. The first layer describes the indi-vidual flocking behavior to the local goal position (the center of minimal circumcircle decided by the neighbors in the positive visual set of individuals) resulting from the individual motion to one or two farthest neighbors in its positive visual set; the second layer describes the emergent aggregating swarm behavior resulting from the individual motion to its local goal position. The scale of the swarm will not be limited because only local individual information is used for modelling in the two-layer topology. We study the stability properties of the swarm emergent behavior based on Lyapunov stability theory. Simulations showed that the swarm system can converge to goal regions while maintaining cohesiveness.
基金Supported by Hunan Provincial Natural Science Foundation of China under Grant No.10JJ6010the Key Project Foundation of Hunan Provincial Education Department of China under Grant No.10A095
文摘We study a system consisting of two identical non-interacting single-mode cavity fields coupled to a common vacuum environment and provide general, explicit, and exact solutions to its master equation by means of the characteristic function method. We analyze the entanglement dynamics of two-mode squeezed thermal state in this model and show that its entanglement dynamics is strongly determined by the two-mode squeezing parameter and the purity. In particular, we find that two-mode squeezed thermal state with the squeezing parameter r ≤ -（1/2） In √u is extremely fragile and almost does not survive in a common vacuum environment. We investigate the time evolution of nonlocality for two-mode squeezed thermal state in such an environment. It is found that the evolved state loses its nonlocality in the beginning of the evolution, but after a time, the revival of nonlocality can occur.
基金国家杰出青年科学基金，the Research Fund for the Doctoral Program of Higher Education of China，国家自然科学基金
文摘The exact solutions of the general nonlinear dynamic system in a new double-chain model of DNA are studied by using both the Conte's Painlevé truncation expansion and the Pickering's truncation expansion. The symmetric kink-kink shape excitations can be found in both the Conte's truncation expansion and the Pickering's truncation expansion. Three types of new localized excitations, the asymmetric kink-kink excitations, the soliton-kink excitation, and the kink-soliton excitations, are found by using the Pickering's nonstandard truncation expansion.
基金Supported by the National Natural Science Foundation of China(51206020)the Program for New Century Excellent Talents in University(NCET-12-0703)the Northeast Petroleum University Foundation
文摘Flow behavior of gas and particles in conical spouted beds is experimentally studied and simulated using the twofluid gas-solid model with the kinetic theory of granular flow.The bed pressure drop and fountain height are measured in a conical spouted bed of 100 mm I.D.at different gas velocities.The simulation results are compared with measurements of bed pressure drop and fountain height.The comparison shows that the drag coefficient model used in cylindrical beds under-predicted bed pressure drop and fountain height in conical spouted beds due to the partial weight of particles supported by the inclined side walls.It is found that the numerical results using the drag coefficient model proposed based on the conical spouted bed in this study are in good agreement with experimental data.The present study provides a useful basis for further works on the CFD simulation of conical spouted bed.
基金Supported by the State Key Development Program for Basic Research of China （No.2006CB200305）, the National Natural Science Foundation of China （No.50376004）, and Ph.D. Program Foundation of Ministry of Education of China （No.20030007028）.
文摘Presently developed two-phase turbulence models under-predict the gas turbulent fluctuation, because their turbulence modification models cannot fully reflect the effect of particles. In this paper, a two-time-scale dissipation model of turbulence modification, developed for the two-phase velocity correlation and for the dissipation rate of gas turbulent kinetic energy, is proposed and used to simulate sudden-expansion and swirling gas-particle flows. The proposed two-time scale model gives better results than the single-time scale model. Besides, a gas turbulence augmentation model accounting for the f＇mite-size particle wake effect in the gas Reynolds stress equation is proposed. The proposed turbulence modification models are used to simulate two-phase pipe flows. It can properly predict both turbulence reduction and turbulence enhancement for a certain size of particles observed in experiments.
文摘AIM: To evaluate the shortand long-term outcomes of bilateral liver resection for bilateral intrahepatic stones. METHODS: We reviewed retrospectively 101 consecutive patients with bilateral intrahepatic stones who underwent bilateral liver resection in the past 10 years. The shortand long-term outcomes of the patients were analyzed. The Cox proportional hazards model was used to identify the risk factors related to stone recurrence. RESULTS: There was no surgical mortality in this group of patients. The surgical morbidity was 28.7%. Stone clearance rate after hepatectomy was 84.2% and final clearance rate was 95.0% following postoperative choledochoscopic lithotripsy. The stone recurrence rate was 7.9% and the occurrence of postoperative cholangitis was 6.5% in a median follow-up period of 54 mo. The Cox proportional hazards model indicated that liver resection range, less than the range of stone distribution (P = 0.015, OR = 2.152) was an independent risk factor linked to stone recurrence. CONCLUSION: Bilateral liver resection is safe and its shortand long-term outcomes are satisfactory for bilateral intrahepatic stones.
