模拟退火算法用于产生城市土地空间布局方案

Simulating annealing for generating the optimal urban land-use plans

本文发展了一种模拟退火算法辅助产生城市土地空间布局方案。首先建立了城市土地空间配置问题的数学模型 ,目标函数是最小化土地开发费用、最大化不同功能地块间的空间协调性。由于问题存在的诸多空间约束条件使得可行的土地利用布局方案的搜寻过程变得十分缓慢 ,采用了将一些空间约束条件结合到目标函数中的方法 ,如结合了距离约束、方向约束、相同土地利用单元的邻近约束和地块形状的紧凑约束等约束条件。应用于湖南省长沙市暮云工业区用地规划的结果表明 ,模拟退火算法是一种辅助城市土地利用规划的有用的。

Urban land-use planning is a complex, time-consuming process and involves complex decision-making problems. Generally, urban land-use planning is a multi-objective and nonlinear programming problem with high dimensionality, but it is difficult to run into numerical and high time cost problems with conventional optimisation tools. Currently, planners have to use some qualitative methods to generate urban land-use plans, this process has long been viewed as a ‘black box’ inside which planners are more or less subjective and the resulting land-use spatial scheme may be non-optimal. This paper develops a method called simulated annealing algorithms for handling such a conflict. The simulated annealing algorithm is quite effective and efficient for dealing with many complicated mathematical models. The mathematical optimisation model for generating optimal urban land-use plans was established, in which two main objectives, the minimum development cost of land and maximum spatial harmony were considered. Since spatial constraint considerably slows down the process of searching feasible solutions, some spatial constraints are straightforwardly integrated into the objective function in our SA, including the contiguity and compact form constraints, while the direction and distance constraints are combined into the objective function by means of adding accessional penalty cost to the objective function. The SA method is successfully applied to generate optimal land-use plans for Muyun industrial district in Changsha city, but a final realistic plan requires more detailed modeling. SA presented in this paper should therefore be regarded as a fast and simple technique useful in an early stage of the decision-making process. However, in order to maintain the transparency of urban land-use planning, robust and simple techniques as simulated annealing are promising.