Urban expansion is a phenomenon of urban space increase,and an important measuring index of the process of urbanization.Taking Shanghai as an example,the changes of urban average height and built-up area were studied ...Urban expansion is a phenomenon of urban space increase,and an important measuring index of the process of urbanization.Taking Shanghai as an example,the changes of urban average height and built-up area were studied to represent city's vertical and horizontal increases respectively,and statistical methods were used to analyze the driving forces of urban expansion.The research drew following conclusions:1) The urban expansion process of Shanghai from 1985 to 2006 had a clear periodic feature,and could be divided into three stages:vertical expansion in dominance,coordinated vertical and horizontal expansion,and horizontal expansion in dominance.2) The average height and quantity of buildings in core city were significantly bigger than those in suburbs,but the changing speed of the latter was faster.And 3) urbanization process was the major driving force for the city's horizontal expansion,while industrial structure improvement was the key driving factor for the vertical expansion.Those two driving forces were simultaneously affected by city's political factors.展开更多
Effects of magnesia fines addition （ 4%, 6% and 8% in mass ） and spinel with different compositions （alumina-rich, magnesia-rich and stoichiometric spi-nel） on thermal expansion behavior of alumina magne-sia casta...Effects of magnesia fines addition （ 4%, 6% and 8% in mass ） and spinel with different compositions （alumina-rich, magnesia-rich and stoichiometric spi-nel） on thermal expansion behavior of alumina magne-sia castables were researched using tabular corundum, magnesia fines, spinel fines, p-A12O3, Secar-71 cement and SiO2 fume as main starting materials. The results show that： （1） thermal expansion coefficients of speci- mens with 4 mass% and 6 mass% magnesia fines have the similar change tendency, increasing slightly with temperature rising ; when magnesia addition is 8 mass% , the thermal expansion coefficient increases ob-viously at Ⅰ 050 ℃ and reaches the peak at 1 350 ℃ ; （2） when MgO content is the same, the specimen with magnesia-rich spinel has the lowest thermal expansion coefficient; （3） for the castables specimens with the same MgO content, the specimen with magnesia has higher thermal expansion coefficient than that with pre-synthesized spin, el, which is related with the secondary spinelization dttriag the heating process.展开更多
基金Under the auspices of the Key Direction in Knowledge Innovation Programs of Chinese Academy of Sciences (No KZCX2-YW-422)National Natural Science Foundation of China (No 40701059)
文摘Urban expansion is a phenomenon of urban space increase,and an important measuring index of the process of urbanization.Taking Shanghai as an example,the changes of urban average height and built-up area were studied to represent city's vertical and horizontal increases respectively,and statistical methods were used to analyze the driving forces of urban expansion.The research drew following conclusions:1) The urban expansion process of Shanghai from 1985 to 2006 had a clear periodic feature,and could be divided into three stages:vertical expansion in dominance,coordinated vertical and horizontal expansion,and horizontal expansion in dominance.2) The average height and quantity of buildings in core city were significantly bigger than those in suburbs,but the changing speed of the latter was faster.And 3) urbanization process was the major driving force for the city's horizontal expansion,while industrial structure improvement was the key driving factor for the vertical expansion.Those two driving forces were simultaneously affected by city's political factors.
文摘Effects of magnesia fines addition （ 4%, 6% and 8% in mass ） and spinel with different compositions （alumina-rich, magnesia-rich and stoichiometric spi-nel） on thermal expansion behavior of alumina magne-sia castables were researched using tabular corundum, magnesia fines, spinel fines, p-A12O3, Secar-71 cement and SiO2 fume as main starting materials. The results show that： （1） thermal expansion coefficients of speci- mens with 4 mass% and 6 mass% magnesia fines have the similar change tendency, increasing slightly with temperature rising ; when magnesia addition is 8 mass% , the thermal expansion coefficient increases ob-viously at Ⅰ 050 ℃ and reaches the peak at 1 350 ℃ ; （2） when MgO content is the same, the specimen with magnesia-rich spinel has the lowest thermal expansion coefficient; （3） for the castables specimens with the same MgO content, the specimen with magnesia has higher thermal expansion coefficient than that with pre-synthesized spin, el, which is related with the secondary spinelization dttriag the heating process.
