Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional c...Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional cylindrical casings.In this study,numerical and experimental investigations into the fragment spatial distribution of a prismatic casing were conducted.A new numerical method,which adds the Lagrangian marker points to the Eulerian grid,was proposed to track the multi-material interfaces and material dynamic fractures.Physical quantity mappings between the Lagrangian marker points and Eulerian grid were achieved by their topological relationship.Thereafter,the fragment spatial distributions of the prismatic casing with different fragment sizes,fragment shapes,and casing geometries were obtained using the numerical method.Moreover,fragment spatial distribution experiments were conducted on the prismatic casing with different fragment sizes and shapes,and the experimental data were compared with the numerical results.The effects of the fragment and casing geometry on the fragment spatial distributions were determined by analyzing the numerical results and experimental data.Finally,a formula including the casing geometry parameters was fitted to predict the fragment spatial distribution of the prismatic casing under internal explosive loading.展开更多
The institutional environment in China has quite evidently changed during modern socio-economic transitions.Driven both by local government and by marketing force,urban social space was redistributed after the reform ...The institutional environment in China has quite evidently changed during modern socio-economic transitions.Driven both by local government and by marketing force,urban social space was redistributed after the reform of urban land and real estate policies.Urban renewal makes for wide differential rent and therefore gentrification is occurring in China.This paper analyzes the background and institutional environment of gentrification in China,and further discusses the process,characteristics and evolutionary mechanisms in the case of Nanjing,through investigation of the attributes of 1075 residential communities built during the 1998-2008 at a macro level,and interviewing the residents and analyzing questionnaires in 6 different and typical communities at a micro level.As a socio-spatial course of two-way interaction,gentrification is divided into 3 stages of incubation,occurrence and fast development,according to the time of landmark events and policy reform on the leasehold of land in Nanjing during socio-economic transition.In terms of the socio-spatial characteristics of gentrification in Nanjing,the gentrification process under the trajectory of urban renewal makes urban social space present a new circle-layer structure;the rise of quite a number of gated communities results in the fragmentation of social space and privatization of public space;the management mode of modern communities and the change of life style have aggravated the indifference of neighborhood relationship of gentrified communities.Based on the empirical evidence of this study,this paper indicates that gentrification is quite different between China and western countries with respect to spatio-temporal order,dominant forces,paths of realization and spatial expression,and it further reveals the dynamic mechanism of gentrification developing in China at the present stage.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11822203and 11702026)。
文摘Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional cylindrical casings.In this study,numerical and experimental investigations into the fragment spatial distribution of a prismatic casing were conducted.A new numerical method,which adds the Lagrangian marker points to the Eulerian grid,was proposed to track the multi-material interfaces and material dynamic fractures.Physical quantity mappings between the Lagrangian marker points and Eulerian grid were achieved by their topological relationship.Thereafter,the fragment spatial distributions of the prismatic casing with different fragment sizes,fragment shapes,and casing geometries were obtained using the numerical method.Moreover,fragment spatial distribution experiments were conducted on the prismatic casing with different fragment sizes and shapes,and the experimental data were compared with the numerical results.The effects of the fragment and casing geometry on the fragment spatial distributions were determined by analyzing the numerical results and experimental data.Finally,a formula including the casing geometry parameters was fitted to predict the fragment spatial distribution of the prismatic casing under internal explosive loading.
基金Under the auspices of European Commission under 7th Framework Programme (No ECUBS–230824)
文摘The institutional environment in China has quite evidently changed during modern socio-economic transitions.Driven both by local government and by marketing force,urban social space was redistributed after the reform of urban land and real estate policies.Urban renewal makes for wide differential rent and therefore gentrification is occurring in China.This paper analyzes the background and institutional environment of gentrification in China,and further discusses the process,characteristics and evolutionary mechanisms in the case of Nanjing,through investigation of the attributes of 1075 residential communities built during the 1998-2008 at a macro level,and interviewing the residents and analyzing questionnaires in 6 different and typical communities at a micro level.As a socio-spatial course of two-way interaction,gentrification is divided into 3 stages of incubation,occurrence and fast development,according to the time of landmark events and policy reform on the leasehold of land in Nanjing during socio-economic transition.In terms of the socio-spatial characteristics of gentrification in Nanjing,the gentrification process under the trajectory of urban renewal makes urban social space present a new circle-layer structure;the rise of quite a number of gated communities results in the fragmentation of social space and privatization of public space;the management mode of modern communities and the change of life style have aggravated the indifference of neighborhood relationship of gentrified communities.Based on the empirical evidence of this study,this paper indicates that gentrification is quite different between China and western countries with respect to spatio-temporal order,dominant forces,paths of realization and spatial expression,and it further reveals the dynamic mechanism of gentrification developing in China at the present stage.
