AN ALGORITHM FOR THE SPATIAL PRICE EQUILIBRIUM PROBLEM ON A GENERAL NETWORK IN THE SPACE OF THE PATH FLOWS*

ABSTRACT. The spatial price equilibrium on a general network may be formulated as a nonlinear-cost mathematical programming problem with simple constraints, when the decision variables are the path flows. The solution of this problem is difficult due to the very large number of variables (paths) and the impracticality of generating all the paths from all the origins to all the destinations. In this paper, we develop a Gauss-Seidel-Newton Projection algorithm and combine it with a restriction strategy. That makes it unnecessary to generate a priori all the paths. This algorithm may be further improved by exploiting the equivalence between the spatial price equilibrium on a general network and the network equilibrium. Computational results that we present in this paper demonstrate the efficiency of the proposed solution algorithms.     

经济学视野下的中国城市空间扩展

城市空间扩展是城市经济学和城市地理学研究领域的重要课题。改革开放之后,随着经济的快速发展和城市化进程的推进,中国城市的空间范围也迅速扩展。近年来关于中国城市空间对外扩展的研究成果日益增多,但现有的实证分析和理论模型,并没有揭示中国城市空间快速扩展的独特因素及其根本动力,特别是忽略了地方政府在其中发挥的关键性作用。本文以城市经济学相关理论模型为基础,结合中国体制背景,构建一个以地方政府为核心的城市经济模型,并运用该模型对中国城市空间扩展及其相关问题进行分析,认为地方政府在中国农地非农化及其土地开发中发挥决定性的作用,现实农业土地租金较低推动了城市空间的额外扩展,外部性收益使得地方政府零地价出让土地仍然有利可图,诸如铁路及其站点建设等外部条件冲击推动城市以蛙跳(飞地)方式对外扩展。     

THE WEBER PROBLEM: FREQUENCY OF DIFFERENT SOLUTION TYPES AND EXTENSION TO REPULSIVE FORCES AND DYNAMIC PROCESSES*

ABSTRACT. The frequency of occurrence of the different types of solutions to the Weber problem is studied. These solutions are: a location at an attraction point due to a dominant force, to incompatible angles, or to concavity; a location at infinity; a location inside the polygon; and a location outside the polygon. Situations involving both attraction and repulsion points are examined in the triangle and in the more-than-three-sided polygon context, and methods for solving the corresponding problems are compared. A trigonometric solution is proposed for the triangle case involving one repulsion and two attraction points. The variation in the frequency of a location at an attraction point when the number of attraction points increases while the number of repulsion points remains the same is observed as well. Implications of the results are studied for the analysis of dynamic location processes.     

UNDERSTANDING SPATIAL INERTIA: CENTER OF GRAVITY,POPULATION DENSITIES,THE WEBER PROBLEM,AND GRAVITY POTENTIAL*

ABSTRACT. In this paper we attempt to clarify the theoretical links between the concepts of “center of gravity” and “point of maximum population density” which describe the present, and the concepts of “minimum of the comprehensive Weber problem” and “maximum comprehensive gravity potential” which guide the future. Critical values of the characteristic parameters of the relevant functions are estimated. Implications for the understanding of spatial inertia are discussed.     

体育服务设施的空间组织优化问题

本文运用中心地方理论,讨论了体育产业化、职业化和体育市场充分发育的背景下,体育服务设施的空间组织的理论化模型。     

空间联系视角的沈阳市多中心城市结构研究

以沈阳市为研究案例,借鉴国际著名团队POLYNET的研究经验并加以改良,进行了空间联系视角的多中心城市结构的实证分析。分别从人口密度分布、就业-居住空间联系网络与企业空间组织网络三个维度来识别沈阳市的人口中心、就业中心与产业中心,综合分析这些"中心"得出四点结论:①城市核心区就业与居住中心构成十字交叉的内循环结构;②浑南新区次中心特征颇具雏形;③外围人口中心、就业中心与产业中心错位发展;④沈阳市呈现不均衡的多中心结构特征。