Purpose: To evaluate the short-term and intermediate-to long-term efficacy and safety of carotid artery stenting(CAS) compared with carotid endarterectomy(CEA). Materials and Methods: The published literature was elec...Purpose: To evaluate the short-term and intermediate-to long-term efficacy and safety of carotid artery stenting(CAS) compared with carotid endarterectomy(CEA). Materials and Methods: The published literature was electronically searched for randomized controlled trials(RCTs) between CAS and CEA for the treatment of carotid stenosis performed from January 2000 to January 2017. The short-term and intermediate-to long-term outcomes were evaluated. Results: We identified 10 RCTs including 7,183 participants with symptomatic or asymptomatic carotid stenosis. Our meta-analysis found different results between the patients with and those without symptoms. In patients with symptomatic carotid stenosis, the total stroke incidence in the CAS group was significantly higher than that in the CEA group within the 30-day periprocedural period(p<0.001); however, the myocardial infarction incidence in the CAS group was significantly lower than that in the CEA group(p<0.05). There was no significant difference between the two groups in the mortality within 30 days post-procedure, but the intermediate-to long-term incidence of stroke or death in the CAS group was higher than that of the CEA group(p<0.05). In contrast, for asymptomatic patients, there were no significant differences between the CAS and CEA groups in the short-and intermediate-to long-term outcomes. Conclusion: For patients with symptomatic carotid stenosis, CEA is associated with an increased risk of myocardial infarction, whereas CAS is correlated with an increased risk of procedurally related strokes. However, for patients with asymptomatic carotid stenosis, no significant difference was found in the efficacy or safety between CAS and CEA.展开更多
To efficiently compute arbitrary propellant grain evolution of the burning surface with uniform and non-uniform burning rate for solid rocket motor,a unified framework of burning surface regression simulation has been...To efficiently compute arbitrary propellant grain evolution of the burning surface with uniform and non-uniform burning rate for solid rocket motor,a unified framework of burning surface regression simulation has been developed based on minimum distance function.In order to speed up the computation of the mini-mum distance between grid nodes of grain and the triangular mesh of burning surface,a fast distance querying method based on the equal size cube voxel structure was employed.An improved marching tetrahedron method based on piecewise linear approximation was carried out on second-order tetrahedral elements,achieved high-efficiency and adequate accuracy of burning surface extraction simultaneously.The cases of star grain,finocyl grain,and non-uniform tube grain were studied to verify the proposed method.The observed result indicates that the grain burnback computation method could realize the accurate simulation on unstructured tetrahedral mesh with a desirable performance on computational time.展开更多
A coupled numerical method for the direct numerical simulation of particle-fluid systems is formulated and implemented, resolving an order of magnitude smaller than particle size. The particle motion is described by t...A coupled numerical method for the direct numerical simulation of particle-fluid systems is formulated and implemented, resolving an order of magnitude smaller than particle size. The particle motion is described by the time-driven hard-sphere model, while the hydrodynamic equations governing fluid flow are solved by the lattice Boltzmann method (LBM), Particle-fluid coupling is realized by an immersed boundary method (IBM), which considers the effect of boundary on surrounding fluid as a restoring force added to the governing equations of the fluid. The proposed scheme is validated in the classical flow-around-cylinder simulations, and preliminary application of this scheme to fluidization is reported, demonstrating it to be a promising computational strategy for better understanding complex behavior in particle-fluid systems.展开更多
A multi-scale hardware and software architecture implementing the EMMS (energy-minimization multi-scale) paradigm is proven to be effective in the simulation of a two-dimensional gas-solid suspension. General purpos...A multi-scale hardware and software architecture implementing the EMMS (energy-minimization multi-scale) paradigm is proven to be effective in the simulation of a two-dimensional gas-solid suspension. General purpose CPUs are employed for macro-scale control and optimization, and many integrated cores (MlCs) operating in multiple-instruction multiple-data mode are used for a molecular dynamics simulation of the solid particles at the meso-scale. Many cores operating in single-instruction multiple- data mode, such as general purpose graphics processing units (GPGPUs), are employed for direct numerical simulation of the fluid flow at the micro-scale using the lattice Boltzmann method. This architecture is also expected to be efficient for the multi-scale simulation of other comolex systems.展开更多
基金This work was supported by grant from the National Science Foundation of China(No.81371662 and No.81601578)
文摘Purpose: To evaluate the short-term and intermediate-to long-term efficacy and safety of carotid artery stenting(CAS) compared with carotid endarterectomy(CEA). Materials and Methods: The published literature was electronically searched for randomized controlled trials(RCTs) between CAS and CEA for the treatment of carotid stenosis performed from January 2000 to January 2017. The short-term and intermediate-to long-term outcomes were evaluated. Results: We identified 10 RCTs including 7,183 participants with symptomatic or asymptomatic carotid stenosis. Our meta-analysis found different results between the patients with and those without symptoms. In patients with symptomatic carotid stenosis, the total stroke incidence in the CAS group was significantly higher than that in the CEA group within the 30-day periprocedural period(p<0.001); however, the myocardial infarction incidence in the CAS group was significantly lower than that in the CEA group(p<0.05). There was no significant difference between the two groups in the mortality within 30 days post-procedure, but the intermediate-to long-term incidence of stroke or death in the CAS group was higher than that of the CEA group(p<0.05). In contrast, for asymptomatic patients, there were no significant differences between the CAS and CEA groups in the short-and intermediate-to long-term outcomes. Conclusion: For patients with symptomatic carotid stenosis, CEA is associated with an increased risk of myocardial infarction, whereas CAS is correlated with an increased risk of procedurally related strokes. However, for patients with asymptomatic carotid stenosis, no significant difference was found in the efficacy or safety between CAS and CEA.
基金the National Natural Science Foundation of China(No.11202224)。
文摘To efficiently compute arbitrary propellant grain evolution of the burning surface with uniform and non-uniform burning rate for solid rocket motor,a unified framework of burning surface regression simulation has been developed based on minimum distance function.In order to speed up the computation of the mini-mum distance between grid nodes of grain and the triangular mesh of burning surface,a fast distance querying method based on the equal size cube voxel structure was employed.An improved marching tetrahedron method based on piecewise linear approximation was carried out on second-order tetrahedral elements,achieved high-efficiency and adequate accuracy of burning surface extraction simultaneously.The cases of star grain,finocyl grain,and non-uniform tube grain were studied to verify the proposed method.The observed result indicates that the grain burnback computation method could realize the accurate simulation on unstructured tetrahedral mesh with a desirable performance on computational time.
基金sponsored by Ministry of Finance under the grant ZDYZ2008-2National Key Science and Technology Project under the grant 2008ZX05014-003-006HZthe Chinese Academy of Sciences under the grant KGCX2-YW-124
文摘A coupled numerical method for the direct numerical simulation of particle-fluid systems is formulated and implemented, resolving an order of magnitude smaller than particle size. The particle motion is described by the time-driven hard-sphere model, while the hydrodynamic equations governing fluid flow are solved by the lattice Boltzmann method (LBM), Particle-fluid coupling is realized by an immersed boundary method (IBM), which considers the effect of boundary on surrounding fluid as a restoring force added to the governing equations of the fluid. The proposed scheme is validated in the classical flow-around-cylinder simulations, and preliminary application of this scheme to fluidization is reported, demonstrating it to be a promising computational strategy for better understanding complex behavior in particle-fluid systems.
基金supported by the National Science Foundation for Distinguished Young Scholars of China under Grant No.21225628the Science Fund for Creative Research Groups of the National Natural Science Foundation of China under Grant No.20821092+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No.XDA07080100the National Natural Science Foundation of China under Grant No. 21206167
文摘A multi-scale hardware and software architecture implementing the EMMS (energy-minimization multi-scale) paradigm is proven to be effective in the simulation of a two-dimensional gas-solid suspension. General purpose CPUs are employed for macro-scale control and optimization, and many integrated cores (MlCs) operating in multiple-instruction multiple-data mode are used for a molecular dynamics simulation of the solid particles at the meso-scale. Many cores operating in single-instruction multiple- data mode, such as general purpose graphics processing units (GPGPUs), are employed for direct numerical simulation of the fluid flow at the micro-scale using the lattice Boltzmann method. This architecture is also expected to be efficient for the multi-scale simulation of other comolex systems.