Economic analysis on the interaction of individual cities and on the spatial changing process of urban agglomeration

Urban agglomeration is developed on the basis of reciprocal interaction among individual cities,and the process can be illustrated by the model of four-sector macro-economy.We elaborate the influencing process of individual urban interaction between two cities with the help of K model,of which,K is calculated through many key economic indexes,such as Marginal Propensity to Consume(MPC) and Marginal Propensity to Export(MPE).The expanding process of urban agglomeration to the entire area relies on urban center intension(CI).With the gradual reduction of CI from the central area to the margin,urban capability expanding to entire area is reduced gradually in the same direction.Many economic factors play their role in this process,these factors including the improvement of technology,the condition of transportation,the reduction of factor cost and the upgrading of industrial construction,which can be used to influence the formation and development of urban agglomeration by impacting the rent curve on the coordinate plane to the rightward and lead to a different expanding velocity in different urban areas.