为研究CRH3动车组气动特性和预防车体局部结构疲劳,保障列车运行安全,文章应用FFC(Fluent for CATIA)软件,对CRH3动车组头车周围压力场及车体表面压力进行流体仿真分析。结果表明:头车车体各部位表面压力的压力梯度随车体几何曲率的增...为研究CRH3动车组气动特性和预防车体局部结构疲劳,保障列车运行安全,文章应用FFC(Fluent for CATIA)软件,对CRH3动车组头车周围压力场及车体表面压力进行流体仿真分析。结果表明:头车车体各部位表面压力的压力梯度随车体几何曲率的增加而增加,车鼻处压力最大;排障器、车顶及车后棱角结构倒圆角后,最大正压力由4220 N/m^(2)减至4150 N/m^(2);不同车速下,车体表面的压力值随车速的提高而增大,最大压力绝对值与车速的平方成正比关系。棱角结构光顺,有效改善了车体周围流场及车体表面压力分布,减小了车鼻处压力水平;高速度是可能导致车鼻等处局部结构疲劳的要素。展开更多
Molten salts play multiple important roles in the electrolysis of solid metal compounds,particularly oxides and sulfides,for the extraction of metals or alloys.Some of these roles are positive in assisting the extract...Molten salts play multiple important roles in the electrolysis of solid metal compounds,particularly oxides and sulfides,for the extraction of metals or alloys.Some of these roles are positive in assisting the extraction of metals,such as dissolving the oxide or sulfide anions,and transporting them to the anode for discharging,and offering the high temperature to lower the kinetic barrier to break the metal-oxygen or metal-sulfur bond.However,molten salts also have unfavorable effects,including electronic conductivity and significant capability of dissolving oxygen and carbon dioxide gases.In addition,although molten salts are relatively simple in terms of composition,physical properties,and decomposition reactions at inert electrodes,in comparison with aqueous electrolytes,the high temperatures of molten salts may promote unwanted electrode-electrolyte interactions.This article reviews briefly and selectively the research and development of the F ray-F arthing-Chen(FFC)Cambridge Process in the past two decades,focusing on observations,understanding,and solutions of various interactions between molten salts and cathodes at different reduction states,including perovskitization,non-wetting of molten salts on pure metals,carbon contamination of products,formation of oxychlorides and calcium intermetallic compounds,and oxygen transfer from the air to the cathode product mediated by oxide anions in the molten salt.展开更多
The FFC Cambridge process is a direct electrodeoxidation process used to reduce metal oxides for metals or alloys in molten salts. Al-Sc compound oxides are used as a precursor which formed upon blending and sintering...The FFC Cambridge process is a direct electrodeoxidation process used to reduce metal oxides for metals or alloys in molten salts. Al-Sc compound oxides are used as a precursor which formed upon blending and sintering Al2O3, Sc2O3 and AI powders and are successfully reduced by using the FFC Cambridge process at 973 K with a constant cell voltage of -3.2 V. This method is applied to the preparation of fine Al3Sc particles, which can give another new view for aluminum industry.展开更多
Using FFC-Cambridge Process to prepare Si from SiO2 is a promising method to prepare nanostructured and highly pure silicon for solar cells.However,the method still has many problems unsolved and the controlling effec...Using FFC-Cambridge Process to prepare Si from SiO2 is a promising method to prepare nanostructured and highly pure silicon for solar cells.However,the method still has many problems unsolved and the controlling effect of the cell voltage on silicon product is not clear.Here we report in this article that nano cluster-like silicon product with purity of 99.95%has been prepared by complete conversion of raw material SiO2,quartz glass plate,using constant cell voltage electrolysis FFC-Cambridge Process.By analysis of XRD,EDS,TEM,HRTEM and ICP-AES as well as the discussion from the thermodynamics calculation,the morphology and components of the product based on the change of cell voltage are clarified.It is clear that pure silicon could be prepared at the cell voltage of 1.7 2.1 V in this reaction system.The silicon material have cluster-like structure which are made of silicon nanoparticles in 20 100 nm size.Interestingly,the cluster-like nano structure of the silicon can be tuned by the used cell voltage.The purity,yield and the energy cost of silicon product prepared at the optimized cell voltage are discussed.The purity of the silicon product could be further improved,hence this method is promising for the preparation of solar grade silicon in future.展开更多
2007年6月23日至25日，我校范平志教授应邀出席了在北京永兴花园酒店举行的首届未来计算论坛FFC＇07（2007Ffrum on Future Computing）．本次论坛邀请了计算机与无线通信网络方面的国内知名教授30余人．FFC＇07由清华大学张尧学教授担...2007年6月23日至25日，我校范平志教授应邀出席了在北京永兴花园酒店举行的首届未来计算论坛FFC＇07（2007Ffrum on Future Computing）．本次论坛邀请了计算机与无线通信网络方面的国内知名教授30余人．FFC＇07由清华大学张尧学教授担任主席，潘毅教授（美国）、马建华教授（日本）、金群教授（日本）和杨天若教授（加拿大）担任组织委员会成员。展开更多
文摘为研究CRH3动车组气动特性和预防车体局部结构疲劳,保障列车运行安全,文章应用FFC(Fluent for CATIA)软件,对CRH3动车组头车周围压力场及车体表面压力进行流体仿真分析。结果表明:头车车体各部位表面压力的压力梯度随车体几何曲率的增加而增加,车鼻处压力最大;排障器、车顶及车后棱角结构倒圆角后,最大正压力由4220 N/m^(2)减至4150 N/m^(2);不同车速下,车体表面的压力值随车速的提高而增大,最大压力绝对值与车速的平方成正比关系。棱角结构光顺,有效改善了车体周围流场及车体表面压力分布,减小了车鼻处压力水平;高速度是可能导致车鼻等处局部结构疲劳的要素。
文摘Molten salts play multiple important roles in the electrolysis of solid metal compounds,particularly oxides and sulfides,for the extraction of metals or alloys.Some of these roles are positive in assisting the extraction of metals,such as dissolving the oxide or sulfide anions,and transporting them to the anode for discharging,and offering the high temperature to lower the kinetic barrier to break the metal-oxygen or metal-sulfur bond.However,molten salts also have unfavorable effects,including electronic conductivity and significant capability of dissolving oxygen and carbon dioxide gases.In addition,although molten salts are relatively simple in terms of composition,physical properties,and decomposition reactions at inert electrodes,in comparison with aqueous electrolytes,the high temperatures of molten salts may promote unwanted electrode-electrolyte interactions.This article reviews briefly and selectively the research and development of the F ray-F arthing-Chen(FFC)Cambridge Process in the past two decades,focusing on observations,understanding,and solutions of various interactions between molten salts and cathodes at different reduction states,including perovskitization,non-wetting of molten salts on pure metals,carbon contamination of products,formation of oxychlorides and calcium intermetallic compounds,and oxygen transfer from the air to the cathode product mediated by oxide anions in the molten salt.
基金The National Natural Science Foundation of China is gratefully acknowledged for financial support under grantNo.50674026
文摘The FFC Cambridge process is a direct electrodeoxidation process used to reduce metal oxides for metals or alloys in molten salts. Al-Sc compound oxides are used as a precursor which formed upon blending and sintering Al2O3, Sc2O3 and AI powders and are successfully reduced by using the FFC Cambridge process at 973 K with a constant cell voltage of -3.2 V. This method is applied to the preparation of fine Al3Sc particles, which can give another new view for aluminum industry.
基金supported by the Solar Energy Initiative of the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KGCX2-YW-395)
文摘Using FFC-Cambridge Process to prepare Si from SiO2 is a promising method to prepare nanostructured and highly pure silicon for solar cells.However,the method still has many problems unsolved and the controlling effect of the cell voltage on silicon product is not clear.Here we report in this article that nano cluster-like silicon product with purity of 99.95%has been prepared by complete conversion of raw material SiO2,quartz glass plate,using constant cell voltage electrolysis FFC-Cambridge Process.By analysis of XRD,EDS,TEM,HRTEM and ICP-AES as well as the discussion from the thermodynamics calculation,the morphology and components of the product based on the change of cell voltage are clarified.It is clear that pure silicon could be prepared at the cell voltage of 1.7 2.1 V in this reaction system.The silicon material have cluster-like structure which are made of silicon nanoparticles in 20 100 nm size.Interestingly,the cluster-like nano structure of the silicon can be tuned by the used cell voltage.The purity,yield and the energy cost of silicon product prepared at the optimized cell voltage are discussed.The purity of the silicon product could be further improved,hence this method is promising for the preparation of solar grade silicon in future.
文摘2007年6月23日至25日，我校范平志教授应邀出席了在北京永兴花园酒店举行的首届未来计算论坛FFC＇07（2007Ffrum on Future Computing）．本次论坛邀请了计算机与无线通信网络方面的国内知名教授30余人．FFC＇07由清华大学张尧学教授担任主席，潘毅教授（美国）、马建华教授（日本）、金群教授（日本）和杨天若教授（加拿大）担任组织委员会成员。
