The effects of Mg and semi solid processing on the creep properties ofA356 A1 alloy were investigated. The results show that the dislocation climb controlled creep is the dominant creep mechanism and it is not affecte...The effects of Mg and semi solid processing on the creep properties ofA356 A1 alloy were investigated. The results show that the dislocation climb controlled creep is the dominant creep mechanism and it is not affected by the semi solid processing and further addition of Mg. Mg improves the alloy creep properties probably by forming large Chinese script Mg2Si compounds at the interdendritic regions. The semi solid processed specimens exhibit better creep properties in comparison with the as cast ones. It is attributed to the reduction in the stacking fault energy resulting from the significant dissolution of Mg in the a（A1） phase.展开更多
Multi-storey housing for low income society is a concept of redevelopment from many alternatives of housing development for slum in Jakarta. However, redevelopment directly or indirectly leads to displacement of low-i...Multi-storey housing for low income society is a concept of redevelopment from many alternatives of housing development for slum in Jakarta. However, redevelopment directly or indirectly leads to displacement of low-income residents. The new residents would be of a higher socio-economic status than the previous occupants. For controlling this phenomenon, a study about the influence of displacement to the successful of sustainable multi-storey housing development for low-income society has been done with descriptive method, observation and literature study. The result of this study give knowledge that displacement always happened when the quality of building and environment is increase, the location of multi-storey housing is near city center and commercial area. Low income society voluntary displaced their units to middle or high income society, because they are not affordable for paying operational and maintenance costs. The government has to make regulations for controlling displacement on multi-storey housing for low-income society and for the successful of sustainable multi-storey housing development in urban area.展开更多
In this paper,elastic metasurfaces composed of zigzag units are proposed to manipulate flexural waves at a deep subwavelength scale.Through the parameter optimization of the genetic algorithm,units with full transmiss...In this paper,elastic metasurfaces composed of zigzag units are proposed to manipulate flexural waves at a deep subwavelength scale.Through the parameter optimization of the genetic algorithm,units with full transmission and full phase control can be found,while the width is only one-fifth of the wavelength.The outstanding capability of the units is explained by analyzing.their wave fields.The flat and the curved metasurfaces for focusing are designed and simulated,showing excellent performance.Experimental results of the flat metasurface show that the incident wave energy at the focal point is enhanced over 6 times,verifying the simulation results.The proposed metasurfaces could be useful in the design of.compact and efficient elastic devices.展开更多
文摘The effects of Mg and semi solid processing on the creep properties ofA356 A1 alloy were investigated. The results show that the dislocation climb controlled creep is the dominant creep mechanism and it is not affected by the semi solid processing and further addition of Mg. Mg improves the alloy creep properties probably by forming large Chinese script Mg2Si compounds at the interdendritic regions. The semi solid processed specimens exhibit better creep properties in comparison with the as cast ones. It is attributed to the reduction in the stacking fault energy resulting from the significant dissolution of Mg in the a（A1） phase.
文摘Multi-storey housing for low income society is a concept of redevelopment from many alternatives of housing development for slum in Jakarta. However, redevelopment directly or indirectly leads to displacement of low-income residents. The new residents would be of a higher socio-economic status than the previous occupants. For controlling this phenomenon, a study about the influence of displacement to the successful of sustainable multi-storey housing development for low-income society has been done with descriptive method, observation and literature study. The result of this study give knowledge that displacement always happened when the quality of building and environment is increase, the location of multi-storey housing is near city center and commercial area. Low income society voluntary displaced their units to middle or high income society, because they are not affordable for paying operational and maintenance costs. The government has to make regulations for controlling displacement on multi-storey housing for low-income society and for the successful of sustainable multi-storey housing development in urban area.
基金supported by the National Natural Science Foundation of China(Grant Nos.12072223,12122207,12021002,11991031,and 11991032)Y.-F.Wang also acknowledges support by the Natural Science Foundation of Tianjin(Grant No.20JCQNJC01030).
文摘In this paper,elastic metasurfaces composed of zigzag units are proposed to manipulate flexural waves at a deep subwavelength scale.Through the parameter optimization of the genetic algorithm,units with full transmission and full phase control can be found,while the width is only one-fifth of the wavelength.The outstanding capability of the units is explained by analyzing.their wave fields.The flat and the curved metasurfaces for focusing are designed and simulated,showing excellent performance.Experimental results of the flat metasurface show that the incident wave energy at the focal point is enhanced over 6 times,verifying the simulation results.The proposed metasurfaces could be useful in the design of.compact and efficient elastic devices.
