Let D be a 2-（v, k, 4） symmetric design and G be a flag-transitive point-primitive automorphism group of D with X ≥G ≤Aut（X） where X ≌ PSL2（q）.Then D is a 2-（15,8,4） symmetric design with X = PSL2（9） and ...Let D be a 2-（v, k, 4） symmetric design and G be a flag-transitive point-primitive automorphism group of D with X ≥G ≤Aut（X） where X ≌ PSL2（q）.Then D is a 2-（15,8,4） symmetric design with X = PSL2（9） and Xx = PGL2（3） where x is a point of D.展开更多
Conventional reliability-based design optimization （RBDO） requires to use the most probable point （MPP） method for a probabilistic analysis of the reliability constraints. A new approach is presented, called as th...Conventional reliability-based design optimization （RBDO） requires to use the most probable point （MPP） method for a probabilistic analysis of the reliability constraints. A new approach is presented, called as the minimum error point （MEP） method or the MEP based method, for reliability-based design optimization, whose idea is to minimize the error produced by approximating performance functions. The MEP based method uses the first order Taylor＇s expansion at MEP instead of MPP. Examples demonstrate that the MEP based design optimization can ensure product reliability at the required level, which is very imperative for many important engineering systems. The MEP based reliability design optimization method is feasible and is considered as an alternative for solving reliability design optimization problems. The MEP based method is more robust than the commonly used MPP based method for some irregular performance functions.展开更多
A systemic investigation was done on the chemistry and crystal structure of boundary phases in sintered Ce9Nd21FebalB1 （wt%） magnets. Ce2Fe14B is believed to be more soluble in the rare-earth （RE）-rich liquid phas...A systemic investigation was done on the chemistry and crystal structure of boundary phases in sintered Ce9Nd21FebalB1 （wt%） magnets. Ce2Fe14B is believed to be more soluble in the rare-earth （RE）-rich liquid phase during the sintering process. Thus, the grain size and oxygen content were controlled via low-temperature sintering, resulting in high coercivity and maximum energy products. In addition, Ce formed massive agglomerations at the triple-point junctions, as confirmed by elemental mapping results. Transmission electron micros- copy （TEM） images indicated the presence of （Ce,Nd）Ox phases at grain boundaries. By controlling the composition and optimizing the preparation process, we successfully obtained Ce9Nd21FebalBx sintered magnets; the prepared magnets exhibited a residual induction, coerciv- ity, and energy product of 1.353 T, 759 kA/m, and 342 kJ/m3, respectively.展开更多
Compared with traditional cast-in-situ concrete slab culverts,prefabricated reinforced concrete slab culverts can be produced more quickly and has strong quality controllability,strong earthquake resistance,and repeat...Compared with traditional cast-in-situ concrete slab culverts,prefabricated reinforced concrete slab culverts can be produced more quickly and has strong quality controllability,strong earthquake resistance,and repeatability.They will be the primary production method of slab culverts in the future.This article offers a comprehensive review of the design and construction technology associated with prefabricated reinforced concrete slab culverts.The objective is to provide a valuable reference for related enterprises,enhance the quality of design and construction in precast pile configuration,and,in turn,contribute to the advancement of construction projects within our country.展开更多
基金Supported by the National Natural Science Foundation of China(11071081)
文摘Let D be a 2-（v, k, 4） symmetric design and G be a flag-transitive point-primitive automorphism group of D with X ≥G ≤Aut（X） where X ≌ PSL2（q）.Then D is a 2-（15,8,4） symmetric design with X = PSL2（9） and Xx = PGL2（3） where x is a point of D.
基金This project is supported by National Natural Science Foundation of China(No.50575072)Outstanding Youth Fund of Hunan Education Department, China (No.04B007).
文摘Conventional reliability-based design optimization （RBDO） requires to use the most probable point （MPP） method for a probabilistic analysis of the reliability constraints. A new approach is presented, called as the minimum error point （MEP） method or the MEP based method, for reliability-based design optimization, whose idea is to minimize the error produced by approximating performance functions. The MEP based method uses the first order Taylor＇s expansion at MEP instead of MPP. Examples demonstrate that the MEP based design optimization can ensure product reliability at the required level, which is very imperative for many important engineering systems. The MEP based reliability design optimization method is feasible and is considered as an alternative for solving reliability design optimization problems. The MEP based method is more robust than the commonly used MPP based method for some irregular performance functions.
基金financially supported by the National Natural Science Foundation of China (No. 51171048)the National High Technology Research and Development Program of China (No. 2014CB643701)the National Science and Technology Support Program of China (No. 2012BAE02B01)
文摘A systemic investigation was done on the chemistry and crystal structure of boundary phases in sintered Ce9Nd21FebalB1 （wt%） magnets. Ce2Fe14B is believed to be more soluble in the rare-earth （RE）-rich liquid phase during the sintering process. Thus, the grain size and oxygen content were controlled via low-temperature sintering, resulting in high coercivity and maximum energy products. In addition, Ce formed massive agglomerations at the triple-point junctions, as confirmed by elemental mapping results. Transmission electron micros- copy （TEM） images indicated the presence of （Ce,Nd）Ox phases at grain boundaries. By controlling the composition and optimizing the preparation process, we successfully obtained Ce9Nd21FebalBx sintered magnets; the prepared magnets exhibited a residual induction, coerciv- ity, and energy product of 1.353 T, 759 kA/m, and 342 kJ/m3, respectively.
文摘Compared with traditional cast-in-situ concrete slab culverts,prefabricated reinforced concrete slab culverts can be produced more quickly and has strong quality controllability,strong earthquake resistance,and repeatability.They will be the primary production method of slab culverts in the future.This article offers a comprehensive review of the design and construction technology associated with prefabricated reinforced concrete slab culverts.The objective is to provide a valuable reference for related enterprises,enhance the quality of design and construction in precast pile configuration,and,in turn,contribute to the advancement of construction projects within our country.
