The tight foreign exchange control era has gone with ,wind, and foreigncurrency reserve of China now is up to 300 billion US dollars;once"the cuffof overseas investment",the foreign exchange control system w...The tight foreign exchange control era has gone with ,wind, and foreigncurrency reserve of China now is up to 300 billion US dollars;once"the cuffof overseas investment",the foreign exchange control system will go where?展开更多
Ice-breaking methods have become increasingly significant with the ongoing development of the polar regions.Among many ice-breaking methods,ice-breaking that utilizes a moving load is unique compared with the common c...Ice-breaking methods have become increasingly significant with the ongoing development of the polar regions.Among many ice-breaking methods,ice-breaking that utilizes a moving load is unique compared with the common collision or impact methods.A moving load can generate flexural-gravity waves(FGWs),under the influence of which the ice sheet undergoes deformation and may even experience structural damage.Moving loads can be divided into above-ice loads and underwater loads.For the above-ice loads,we discuss the characteristics of the FGWs generated by a moving load acting on a complete ice sheet,an ice sheet with a crack,and an ice sheet with a lead of open water.For underwater loads,we discuss the influence on the ice-breaking characteristics of FGWs of the mode of motion,the geometrical features,and the trajectory of motion of the load.In addition to discussing the status of current research and the technical challenges of ice-breaking by moving loads,this paper also looks ahead to future research prospects and presents some preliminary ideas for consideration.展开更多
A multi-resolution smoothed particle hydrodynamics and peridynamics(SPH-PD)coupling model is proposed in this study for simulating the fracture characteristics of ice plates exposed to underwater blast loads.The SPH m...A multi-resolution smoothed particle hydrodynamics and peridynamics(SPH-PD)coupling model is proposed in this study for simulating the fracture characteristics of ice plates exposed to underwater blast loads.The SPH model employs a volume adaptive scheme(VAS)and a multi-resolution particle technique to accurately simulate explosive charge detonation and shock wave propagation.This approach addresses numerical challenges from charge expansion and significant size disparity between the charge and the fluid particles.The model captures the full underwater explosion process,covering both the shock wave phase and the bubble expansion stage,by applying appropriate equations of state for each respective phase.To analyze ice plate damage and crack propagation influenced by temperature changes,an ordinary state-based PD(OSB-PD)formulation with coupled mechanical and thermodynamic models is used.Numerical results show that the proposed coupling method demonstrates good agreement with reference solutions and experimental data.展开更多
This letter presents a critical analysis of the study by Zhao et al,which proposed a therapeutic strategy for difficult common bile duct stones focusing on the"icebreaking sign"as a pivotal radiological feat...This letter presents a critical analysis of the study by Zhao et al,which proposed a therapeutic strategy for difficult common bile duct stones focusing on the"icebreaking sign"as a pivotal radiological feature.Based on magnetic resonance cholangiopancreatography with three-dimensional reconstruction,the diagnostic criteria for this sign were established by identifying an abrupt narrowing at the distal bile duct caused by impacted stones,analogous to the morphology of an icebreaking vessel.Specifically,the proximal bile duct(hepatic hilar side)exhibited significant dilatation upstream of the stenosis,while the distal segment(duodenal papillary side)presented with stricture or occlusion.This study was the first to introduce the radiological marker termed the"ice-breaking sign",providing a novel dimension for the evaluation of refractory common bile duct stones.However,notable limitations were also present in this study.The interpretation of the ice-breaking sign depended largely on subjective assessments by physicians,even though a multidisciplinary consensus approach was employed.Objective quantification criteria,such as specific thresholds for the degree of stenosis,were not established.Furthermore,being a single-center study,it might have influenced the reproducibility of findings across different centers.Future studies should explore the pathophysiological mechanisms of the"ice-breaking sign"in greater depth,increase the sample size,and conduct multicenter research to validate its clinical universality and guiding significance for treatment strategies.展开更多
This study investigates the resistance of a transport ship navigating in level ice by conducting a series of model tests in an ice tank at Tianjin University. The laboratory-scale model ship was mounted on a rigid car...This study investigates the resistance of a transport ship navigating in level ice by conducting a series of model tests in an ice tank at Tianjin University. The laboratory-scale model ship was mounted on a rigid carriage using a one-directional load cell and then towed through an ice sheet at different speeds. We observed the ice-breaking process at different parts of the ship and motion of the ice floes and measured the resistances under different speeds to determine the relationship between the ice-breaking process and ice resistance. The bending failure at the shoulder area was found to cause maximum resistance. Furthermore, we introduced the analytical method of Lindqvist （1989） for estimating ice resistance and then compared these calculated results with those from our model tests. The results indicate that the calculated total resistances are higher than those we determined in the model tests.展开更多
文摘The tight foreign exchange control era has gone with ,wind, and foreigncurrency reserve of China now is up to 300 billion US dollars;once"the cuffof overseas investment",the foreign exchange control system will go where?
基金Supported by the National Natural Science Foundation of China(Nos.52192693,52192690,52371270,U20A20327)the National Key Research and Development Program of China(Nos.2021YFC2803400).
文摘Ice-breaking methods have become increasingly significant with the ongoing development of the polar regions.Among many ice-breaking methods,ice-breaking that utilizes a moving load is unique compared with the common collision or impact methods.A moving load can generate flexural-gravity waves(FGWs),under the influence of which the ice sheet undergoes deformation and may even experience structural damage.Moving loads can be divided into above-ice loads and underwater loads.For the above-ice loads,we discuss the characteristics of the FGWs generated by a moving load acting on a complete ice sheet,an ice sheet with a crack,and an ice sheet with a lead of open water.For underwater loads,we discuss the influence on the ice-breaking characteristics of FGWs of the mode of motion,the geometrical features,and the trajectory of motion of the load.In addition to discussing the status of current research and the technical challenges of ice-breaking by moving loads,this paper also looks ahead to future research prospects and presents some preliminary ideas for consideration.
基金partially funded by the National Natural Science Foundation of China(Grant No.52171329)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2024B1515020107)+1 种基金the Young Elite Scientist Sponsorship Program by CAST(Grant No.2022QNRC001)Characteristic Innovation Project of Universities in Guangdong Province(Grant No.2023KTSCX005).
文摘A multi-resolution smoothed particle hydrodynamics and peridynamics(SPH-PD)coupling model is proposed in this study for simulating the fracture characteristics of ice plates exposed to underwater blast loads.The SPH model employs a volume adaptive scheme(VAS)and a multi-resolution particle technique to accurately simulate explosive charge detonation and shock wave propagation.This approach addresses numerical challenges from charge expansion and significant size disparity between the charge and the fluid particles.The model captures the full underwater explosion process,covering both the shock wave phase and the bubble expansion stage,by applying appropriate equations of state for each respective phase.To analyze ice plate damage and crack propagation influenced by temperature changes,an ordinary state-based PD(OSB-PD)formulation with coupled mechanical and thermodynamic models is used.Numerical results show that the proposed coupling method demonstrates good agreement with reference solutions and experimental data.
文摘This letter presents a critical analysis of the study by Zhao et al,which proposed a therapeutic strategy for difficult common bile duct stones focusing on the"icebreaking sign"as a pivotal radiological feature.Based on magnetic resonance cholangiopancreatography with three-dimensional reconstruction,the diagnostic criteria for this sign were established by identifying an abrupt narrowing at the distal bile duct caused by impacted stones,analogous to the morphology of an icebreaking vessel.Specifically,the proximal bile duct(hepatic hilar side)exhibited significant dilatation upstream of the stenosis,while the distal segment(duodenal papillary side)presented with stricture or occlusion.This study was the first to introduce the radiological marker termed the"ice-breaking sign",providing a novel dimension for the evaluation of refractory common bile duct stones.However,notable limitations were also present in this study.The interpretation of the ice-breaking sign depended largely on subjective assessments by physicians,even though a multidisciplinary consensus approach was employed.Objective quantification criteria,such as specific thresholds for the degree of stenosis,were not established.Furthermore,being a single-center study,it might have influenced the reproducibility of findings across different centers.Future studies should explore the pathophysiological mechanisms of the"ice-breaking sign"in greater depth,increase the sample size,and conduct multicenter research to validate its clinical universality and guiding significance for treatment strategies.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 51179123 and 51279131
文摘This study investigates the resistance of a transport ship navigating in level ice by conducting a series of model tests in an ice tank at Tianjin University. The laboratory-scale model ship was mounted on a rigid carriage using a one-directional load cell and then towed through an ice sheet at different speeds. We observed the ice-breaking process at different parts of the ship and motion of the ice floes and measured the resistances under different speeds to determine the relationship between the ice-breaking process and ice resistance. The bending failure at the shoulder area was found to cause maximum resistance. Furthermore, we introduced the analytical method of Lindqvist （1989） for estimating ice resistance and then compared these calculated results with those from our model tests. The results indicate that the calculated total resistances are higher than those we determined in the model tests.
