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
Recently, it has been found that geometric structures of the surface of metal materials relate to their physical performance. The surfaces of many metal materials have a character of fractal. And we can learn their in...Recently, it has been found that geometric structures of the surface of metal materials relate to their physical performance. The surfaces of many metal materials have a character of fractal. And we can learn their internal properties by studying the appearances of metal materials. It also has been discovered that there is a relationship between fractal dimension of the surface of metal fracture and the flexibility of fracture. Therefore,展开更多
In this work,the effects of nanoparticle size,particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated.Both size and pH are found to significantly affect nanocollo...In this work,the effects of nanoparticle size,particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated.Both size and pH are found to significantly affect nanocolloid viscosity.Two models are used to study the effect of aggregate structure on the viscosity of the nanocolloidal dispersion.The fractal concept is introduced to describe the irregular and dynamic aggregate structure.The structure of aggregates,which is considered to play an important role in viscosity,is affected by both intermolecular and electrostatic forces.The particle interaction is primarily affected by particle distance and becomes stronger with decreasing particle size and increasing volume fraction.The aggregate structure is also affected by the pH of the solution.Studying the relationship between pH and zeta-potential shows that with the neutralization of charges on the particle surface and decreasing electrical repulsion force,the particle interaction becomes dominated by attractive forces and the aggregates form a more compact structure.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.
基金Project supported by the Natural Science Foundation of Fujian Province
文摘Recently, it has been found that geometric structures of the surface of metal materials relate to their physical performance. The surfaces of many metal materials have a character of fractal. And we can learn their internal properties by studying the appearances of metal materials. It also has been discovered that there is a relationship between fractal dimension of the surface of metal fracture and the flexibility of fracture. Therefore,
基金supported by the Research Foundation of Science and Technology Department of Zhejiang Province,China (2009C21023)the China Postdoctoral Science Foundation (20080441248)
文摘In this work,the effects of nanoparticle size,particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated.Both size and pH are found to significantly affect nanocolloid viscosity.Two models are used to study the effect of aggregate structure on the viscosity of the nanocolloidal dispersion.The fractal concept is introduced to describe the irregular and dynamic aggregate structure.The structure of aggregates,which is considered to play an important role in viscosity,is affected by both intermolecular and electrostatic forces.The particle interaction is primarily affected by particle distance and becomes stronger with decreasing particle size and increasing volume fraction.The aggregate structure is also affected by the pH of the solution.Studying the relationship between pH and zeta-potential shows that with the neutralization of charges on the particle surface and decreasing electrical repulsion force,the particle interaction becomes dominated by attractive forces and the aggregates form a more compact structure.
