Taken fractal dimension, compact ratio, urban centroid and urban principal axis as the urban spatial characteristic indices, Tianjin city＇s urban area is investigated in the last 26 years in a quantitative perspectiv...Taken fractal dimension, compact ratio, urban centroid and urban principal axis as the urban spatial characteristic indices, Tianjin city＇s urban area is investigated in the last 26 years in a quantitative perspective, and its traits and changes during different periods are also analyzed. It is clear that these indices can not only scientifically and explicitly assess the urban morphology, urban direction and its changes and trends, but also uncover long-term effects of economy and urban planning on urban morphology.展开更多
以重庆主城区1986、1995、2004、2007、2010及2014年Land Sat TM遥感影像作为数据源,在利用GIS技术对重庆主城区城市用地提取的基础上,运用空间叠加技术对重庆主城区城市用地扩展进行方向划分,同时选择城市扩展指数、扩展重心迁移模型...以重庆主城区1986、1995、2004、2007、2010及2014年Land Sat TM遥感影像作为数据源,在利用GIS技术对重庆主城区城市用地提取的基础上,运用空间叠加技术对重庆主城区城市用地扩展进行方向划分,同时选择城市扩展指数、扩展重心迁移模型、紧凑度、分形维数和弹性系数的研究方法,系统分析重庆主城区城市用地扩展的时空特征;结果表明:近30年间,重庆主城区城市用地增加527 km^2,年均扩展速率达到18.82 km^2;正北、正西和西北方向扩展面积较大,东南方向扩展面积较小,城市重心坐标整体向北偏移;受到自然条件的限制,城市用地扩展表现为组团式、非紧凑的形态,以后的城市用地扩展应更加注重建成区内部的填充;研究结果有助于了解重庆主城区城市用地扩展的时空变化特征,为重庆主城区的城市规划和可持续发展提供参考依据。展开更多
Based on hot metal pretreatment （HMPT）-basic oxygen furnace （BOF）-Rheinstahl Heraeus （RH）-compact strip production （CSP） process, parameters controlling on cold rolling deep drawing substrate SPHE were investi...Based on hot metal pretreatment （HMPT）-basic oxygen furnace （BOF）-Rheinstahl Heraeus （RH）-compact strip production （CSP） process, parameters controlling on cold rolling deep drawing substrate SPHE were investigated during smelting and rolling process by composition design and technology control. The influence of parameters on chemical compositions, mechanical properties and microstructure was revealed by scanning electron microscope （SEM）. The results show that, 1） main chemical components in SPHE are w（C）_〈40×10^-6, w（Si）_〈 0.01%, w（S）_〈0.009%, w（N）〈20×10^-6, w（O）〈_ 25×10^-6; 2） main mechanical properties of the SPHE are Crs=274 MPa, 00=334 MPa, A=48.9%; 3） main performances of deep drawing quality （DDQ） grade steel produced by SPHE are as follows, transversely crs=167 MPa, 00=298 MPa, n=0.219, r=2.46; vertically σs=166 MPa, 00=298 MPa, n=0.226, r=2.39; in 45° direction σ=171 MPa, 00=308 MPa, n=0.214, t=2.26; 4） microstrueture of DDQ is ferrite, average grain size is Grade 7.5, and inclusion size is 3-10μm.展开更多
基金National Basic Research Program of China (973 Program), No.2002CB412507
文摘Taken fractal dimension, compact ratio, urban centroid and urban principal axis as the urban spatial characteristic indices, Tianjin city＇s urban area is investigated in the last 26 years in a quantitative perspective, and its traits and changes during different periods are also analyzed. It is clear that these indices can not only scientifically and explicitly assess the urban morphology, urban direction and its changes and trends, but also uncover long-term effects of economy and urban planning on urban morphology.
文摘以重庆主城区1986、1995、2004、2007、2010及2014年Land Sat TM遥感影像作为数据源,在利用GIS技术对重庆主城区城市用地提取的基础上,运用空间叠加技术对重庆主城区城市用地扩展进行方向划分,同时选择城市扩展指数、扩展重心迁移模型、紧凑度、分形维数和弹性系数的研究方法,系统分析重庆主城区城市用地扩展的时空特征;结果表明:近30年间,重庆主城区城市用地增加527 km^2,年均扩展速率达到18.82 km^2;正北、正西和西北方向扩展面积较大,东南方向扩展面积较小,城市重心坐标整体向北偏移;受到自然条件的限制,城市用地扩展表现为组团式、非紧凑的形态,以后的城市用地扩展应更加注重建成区内部的填充;研究结果有助于了解重庆主城区城市用地扩展的时空变化特征,为重庆主城区的城市规划和可持续发展提供参考依据。
基金Project(50971135) supported by the National Natural Science Foundation of China
文摘Based on hot metal pretreatment （HMPT）-basic oxygen furnace （BOF）-Rheinstahl Heraeus （RH）-compact strip production （CSP） process, parameters controlling on cold rolling deep drawing substrate SPHE were investigated during smelting and rolling process by composition design and technology control. The influence of parameters on chemical compositions, mechanical properties and microstructure was revealed by scanning electron microscope （SEM）. The results show that, 1） main chemical components in SPHE are w（C）_〈40×10^-6, w（Si）_〈 0.01%, w（S）_〈0.009%, w（N）〈20×10^-6, w（O）〈_ 25×10^-6; 2） main mechanical properties of the SPHE are Crs=274 MPa, 00=334 MPa, A=48.9%; 3） main performances of deep drawing quality （DDQ） grade steel produced by SPHE are as follows, transversely crs=167 MPa, 00=298 MPa, n=0.219, r=2.46; vertically σs=166 MPa, 00=298 MPa, n=0.226, r=2.39; in 45° direction σ=171 MPa, 00=308 MPa, n=0.214, t=2.26; 4） microstrueture of DDQ is ferrite, average grain size is Grade 7.5, and inclusion size is 3-10μm.
