Based on the characteristics of large flow rate , low head , short annual operation time , and high reliability of the city flood-control pumping stations , a new-type shaft tubular pumping system featuring a shaft su...Based on the characteristics of large flow rate , low head , short annual operation time , and high reliability of the city flood-control pumping stations , a new-type shaft tubular pumping system featuring a shaft suction box and a siphon-type discharge passage with a vacuum breaker as the cutoff device was developed , which possesses such advantages as simple structure , reliable cutoff , and high energy performance.Taking some pumping stations as the case studies , in the light of the specified operation conditions , the hydraulic optimal design of the shaft-type tubular pumping system was determined and the optimized shape of the system was recommended.The performance prediction based on the computational fluid dynamics methodology was determined and the model test verification was conducted.The results show that the predicted data agree with the experimental head and efficiency so that both methods can be used to determine the performance of a real pumping station.Finally , the in-situ measurements of a pumping station during the commissioning period further verified that the shaft-type tubular pumping station with a siphon discharge passage is of higher efficiency , more reliable and stable.展开更多
The best tissue-engineered spinal cord grafts not only match the structural characteristics of the spinal cord but also allow the seed cells to grow and function in situ.Platelet-derived growth factor（PDGF） has been...The best tissue-engineered spinal cord grafts not only match the structural characteristics of the spinal cord but also allow the seed cells to grow and function in situ.Platelet-derived growth factor（PDGF） has been shown to promote the migration of bone marrow stromal cells;however,cytokines need to be released at a steady rate to maintain a stable concentration in vivo.Therefore,new methods are needed to maintain an optimal concentration of cytokines over an extended period of time to effectively promote seed cell localization,proliferation and differentiation.In the present study,a partition-type tubular scaffold matching the anatomical features of the thoracic 8–10 spinal cord of the rat was fabricated using chitosan and then subsequently loaded with chitosan-encapsulated PDGF-BB microspheres（PDGF-MSs）.The PDGF-MS-containing scaffold was then examined in vitro for sustained-release capacity,biocompatibility,and its effect on neural progenitor cells differentiated in vitro from multilineage-differentiating stress-enduring cells（MUSE-NPCs）.We found that pre-freezing for 2 hours at-20°C significantly increased the yield of partition-type tubular scaffolds,and 30 μL of 25% glutaraldehyde ensured optimal crosslinking of PDGF-MSs.The resulting PDGF-MSs cumulatively released 52% of the PDGF-BB at 4 weeks in vitro without burst release.The PDGF-MS-containing tubular scaffold showed suitable biocompatibility towards MUSE-NPCs and could promote the directional migration and growth of these cells.These findings indicate that the combination of a partition-type tubular scaffold,PDGF-MSs and MUSENPCs may be a promising model for the fabrication of tissue-engineered spinal cord grafts.展开更多
Random fatigue of welded K-type tubular joints subjected to axial or out-of-plane bending load is analyzed. By considering the sizes of initial surface cracks and material constants as random variables with some proba...Random fatigue of welded K-type tubular joints subjected to axial or out-of-plane bending load is analyzed. By considering the sizes of initial surface cracks and material constants as random variables with some probabilistic distributions, incorporating the effect of the weld, five hundred random samples are generated. Statistical computational results of life of crack propagation and effect of change of crack shape are finally obtained and compared with experimental data available based on a regression analysis. Meanwhile, crack propagation behaviors are also investigated.展开更多
基金support by the 11th Five Year Key Project of China’s National Scientific Supporting Plan(Grant No.2006BAB04A03)the Hydraulic Engineering Project from the Water Resources Department of Jiangsu Province(Grant No.2010023)
文摘Based on the characteristics of large flow rate , low head , short annual operation time , and high reliability of the city flood-control pumping stations , a new-type shaft tubular pumping system featuring a shaft suction box and a siphon-type discharge passage with a vacuum breaker as the cutoff device was developed , which possesses such advantages as simple structure , reliable cutoff , and high energy performance.Taking some pumping stations as the case studies , in the light of the specified operation conditions , the hydraulic optimal design of the shaft-type tubular pumping system was determined and the optimized shape of the system was recommended.The performance prediction based on the computational fluid dynamics methodology was determined and the model test verification was conducted.The results show that the predicted data agree with the experimental head and efficiency so that both methods can be used to determine the performance of a real pumping station.Finally , the in-situ measurements of a pumping station during the commissioning period further verified that the shaft-type tubular pumping station with a siphon discharge passage is of higher efficiency , more reliable and stable.
基金supported by the Natural Science Foundation of China,No.81501610,81350030the Priority Academic Program Development of Jiangsu Higher Education Institutes of China
文摘The best tissue-engineered spinal cord grafts not only match the structural characteristics of the spinal cord but also allow the seed cells to grow and function in situ.Platelet-derived growth factor（PDGF） has been shown to promote the migration of bone marrow stromal cells;however,cytokines need to be released at a steady rate to maintain a stable concentration in vivo.Therefore,new methods are needed to maintain an optimal concentration of cytokines over an extended period of time to effectively promote seed cell localization,proliferation and differentiation.In the present study,a partition-type tubular scaffold matching the anatomical features of the thoracic 8–10 spinal cord of the rat was fabricated using chitosan and then subsequently loaded with chitosan-encapsulated PDGF-BB microspheres（PDGF-MSs）.The PDGF-MS-containing scaffold was then examined in vitro for sustained-release capacity,biocompatibility,and its effect on neural progenitor cells differentiated in vitro from multilineage-differentiating stress-enduring cells（MUSE-NPCs）.We found that pre-freezing for 2 hours at-20°C significantly increased the yield of partition-type tubular scaffolds,and 30 μL of 25% glutaraldehyde ensured optimal crosslinking of PDGF-MSs.The resulting PDGF-MSs cumulatively released 52% of the PDGF-BB at 4 weeks in vitro without burst release.The PDGF-MS-containing tubular scaffold showed suitable biocompatibility towards MUSE-NPCs and could promote the directional migration and growth of these cells.These findings indicate that the combination of a partition-type tubular scaffold,PDGF-MSs and MUSENPCs may be a promising model for the fabrication of tissue-engineered spinal cord grafts.
文摘Random fatigue of welded K-type tubular joints subjected to axial or out-of-plane bending load is analyzed. By considering the sizes of initial surface cracks and material constants as random variables with some probabilistic distributions, incorporating the effect of the weld, five hundred random samples are generated. Statistical computational results of life of crack propagation and effect of change of crack shape are finally obtained and compared with experimental data available based on a regression analysis. Meanwhile, crack propagation behaviors are also investigated.
