摘要
从空间复杂性及空间尺度和空间维数方面研究了异速生长定律与Clark定律存在的模型相容性和模型参数一致性问题.结果表明,城市人口密度分布与城市人口-城区面积异速生长幂次定律的矛盾,本质上是一种空间复杂性问题.三维的空间投影到二维必然导致复杂的结果,不同维数的空间逻辑链接也会表现出复杂行为,解决这个问题的办法是将研究对象的维度保持一致.
The relationships of allometric growth between urban area and population should be reduced to urban density models of land-use and population distribution theoretically, and in turn it should be derived from urban density functions. The precondition of the transformation mentioned above is that both urban population and urban land use density follow the same scaling law: either negative exponential or inverse power function. However, the urban population density in real world complies with the Clark's law, namely the negative exponential function, while the urban land use density conforms to the inverse power function. The sticking point lies in that urban population is defined in 3-dimension space with land use in 2-dimension space. Spatial complexity appears while an object in 3-d is projected to 2-d. If population of cities are taken into account in only 2-d space, the space dimension is harmonized and maybe the logic contradiction can be eliminated. In this case, the issue of the dimension consistency must be considered,which can be formulated as a relation b=D/d. Where b is the scaling factor of the model allometric growth, D is the dimension of urban land use, and d the dimension of urban population. When the allometric model is reduced to the power function named Smeed's model, the exponent α must abide by the relation such as α=2-d, where d is dimension of city population. Now that d value comes between 1 and 2, α is supposed to be smaller than 1, namely α<1. This is a very important criterion used to judge if urban population of a city conforms to Smeed's model: no matter when the exponent appears greater than 1, it implies that the city fails to comply with the power law. On the other hand, when the observed data follow power-law distribution with the exponent smaller than 1, the urban population can be regarded as self-similar and the fractal geometry can be employed to analyze the city system.
出处
《东北师大学报（自然科学版）》
CAS
CSCD
北大核心
2004年第4期139-148,共10页
Journal of Northeast Normal University(Natural Science Edition)
基金
国家自然科学基金资助项目(40371039)
关键词
城市密度
异速生长
距离衰减效应
分形维数
空间复杂性
urban density
allometric growth
distance-decay effect
fractal dimension
spatial complexity
