针对我国铁路桥梁占比高、标准构件应用范围广、孔跨布置作业繁重的特点,将建筑信息模型(BIM,Building Information Modeling)与人工智能(AI,Artificial Intelligence)技术相结合,进行桥梁智能布跨研究。文章根据桥梁布跨原则,基于信息...针对我国铁路桥梁占比高、标准构件应用范围广、孔跨布置作业繁重的特点,将建筑信息模型(BIM,Building Information Modeling)与人工智能(AI,Artificial Intelligence)技术相结合,进行桥梁智能布跨研究。文章根据桥梁布跨原则,基于信息集,选用Q-Learning算法对Bentley平台二次开发,形成了一套完整的可视化桥梁布跨方案。验证结果表明,该方案可应用于一般铁路桥梁设计中,并从设计层提高BIM数据应用深度与广度,提高桥梁布跨工作效率与质量。展开更多
Modem long-span space structures,developed during the 1970s and 1980s,are light and effective structures based on new technologies and light-weight high-strength materials,such as membranes and steel cables.These stru...Modem long-span space structures,developed during the 1970s and 1980s,are light and effective structures based on new technologies and light-weight high-strength materials,such as membranes and steel cables.These structures include air-supported membrane structures,cable-membrane structures,cable truss structures,beam string structures,suspen-domes,cable domes,composite structures of cable dome and single-layer lattice shell,Tensairity structures and so forth.For the premodem space structures widely used since the mid-twentieth century(such as thin shells,space trusses,lattice shells and ordinary cable structures),new space structures have been developed by the combination of different structural forms and materials.The application of prestressing technology and the innovation of structural concepts and configurations are also associated with modem space structures,including composite space trusses,open-web grid structures,polyhedron space frame structures,partial double-layer lattice shells,cable-stayed grid structures,tree-type structures,prestressed segmental steel structures and so forth.This paper provides a review of the structural characteristics and practical applications in China of modem rigid space structures,modem flexible space structures and modem rigid-flexible combined space structures.展开更多
The aim of this study was to investigate the toxic effects of aluminum （A1） on the model organism-Drosophila melanogaster. The study is especially concerned with the effects of aluminum on the fruit fly＇s developme...The aim of this study was to investigate the toxic effects of aluminum （A1） on the model organism-Drosophila melanogaster. The study is especially concerned with the effects of aluminum on the fruit fly＇s development, life span, and circadian rhythm in rest and activity. Flies were exposed to aluminum in concentrations from 40 to 280 mg/kg in rearing media or the flies were raised on control medium. Moreover, the life span of insects exposed to aluminum containing 40, 120, or 240 mg/kg of A1 in the medium, only during their larval development, during the whole life cycle and only in their adult life was tested. To check if aluminum and aging cause changes in D. melanogaster behavior, the locomotor activity of flies at different ages was recorded. Results showed that aluminum is toxic in concentrations above 160 mg/kg in the rearing medium. Depending on A1 concentration and time of exposure, the life span of the flies was shortened. At intermediate concentrations （120 mg/kg）, however, A1 had a stimulating effect on males increasing their life span and level of locomotor activity. At higher concentration the aluminum exposure increased or decreased the level of locomotor activity ofD. melanogaster depending on age of flies. In addition, in the oldest insects reared on aluminum supplemented media and in mid-aged flies reared on the highest concentration of A1 the daily rhythm of activity was disrupted.展开更多
文摘针对我国铁路桥梁占比高、标准构件应用范围广、孔跨布置作业繁重的特点,将建筑信息模型(BIM,Building Information Modeling)与人工智能(AI,Artificial Intelligence)技术相结合,进行桥梁智能布跨研究。文章根据桥梁布跨原则,基于信息集,选用Q-Learning算法对Bentley平台二次开发,形成了一套完整的可视化桥梁布跨方案。验证结果表明,该方案可应用于一般铁路桥梁设计中,并从设计层提高BIM数据应用深度与广度,提高桥梁布跨工作效率与质量。
文摘Modem long-span space structures,developed during the 1970s and 1980s,are light and effective structures based on new technologies and light-weight high-strength materials,such as membranes and steel cables.These structures include air-supported membrane structures,cable-membrane structures,cable truss structures,beam string structures,suspen-domes,cable domes,composite structures of cable dome and single-layer lattice shell,Tensairity structures and so forth.For the premodem space structures widely used since the mid-twentieth century(such as thin shells,space trusses,lattice shells and ordinary cable structures),new space structures have been developed by the combination of different structural forms and materials.The application of prestressing technology and the innovation of structural concepts and configurations are also associated with modem space structures,including composite space trusses,open-web grid structures,polyhedron space frame structures,partial double-layer lattice shells,cable-stayed grid structures,tree-type structures,prestressed segmental steel structures and so forth.This paper provides a review of the structural characteristics and practical applications in China of modem rigid space structures,modem flexible space structures and modem rigid-flexible combined space structures.
文摘The aim of this study was to investigate the toxic effects of aluminum （A1） on the model organism-Drosophila melanogaster. The study is especially concerned with the effects of aluminum on the fruit fly＇s development, life span, and circadian rhythm in rest and activity. Flies were exposed to aluminum in concentrations from 40 to 280 mg/kg in rearing media or the flies were raised on control medium. Moreover, the life span of insects exposed to aluminum containing 40, 120, or 240 mg/kg of A1 in the medium, only during their larval development, during the whole life cycle and only in their adult life was tested. To check if aluminum and aging cause changes in D. melanogaster behavior, the locomotor activity of flies at different ages was recorded. Results showed that aluminum is toxic in concentrations above 160 mg/kg in the rearing medium. Depending on A1 concentration and time of exposure, the life span of the flies was shortened. At intermediate concentrations （120 mg/kg）, however, A1 had a stimulating effect on males increasing their life span and level of locomotor activity. At higher concentration the aluminum exposure increased or decreased the level of locomotor activity ofD. melanogaster depending on age of flies. In addition, in the oldest insects reared on aluminum supplemented media and in mid-aged flies reared on the highest concentration of A1 the daily rhythm of activity was disrupted.
