城市人口与就业分布的空间耦合与互动机制研究的瓶颈问题之一在于城市空间的多情景模拟.工作流技术能在异构环境中处理复杂事务,同时具有易分享、可执行、任务自动化等特征,是实现可重复、可拓展执行地理分析功能的有效途径.该文将工作流技术引入城市人口与就业分布多情景模拟,基于KNIME平台开发Garin-Lowry模型工作流系统,该系统包括数据查询与输入输出、模型计算和结果分析3个模块;根据Garin-Lowry模型的核心变量设置多种基础就业及交通网络情景,比较同心圆、矩形网格和蜂窝状3种理想城市形态下,不同基础就业中心格局下城市人口与就业的空间结构特征,同时模拟路网局部与整体提速的城市人口与就业分布变化.结果表明,城市形态对城市职住格局影响微弱,但就业中心格局和路网条件对城市人口与就业空间分布影响显著,就业中心越分散、距离摩擦系数越小,人口的空间扩散效应越显著,进一步证实了城市科学中提出的"甜甜圈效应""丝带假说",也为城市规划提供了政策模拟工具.
The spatial coupling and interactive mechanisms between urban population and employment distribution have al-ways been a hot topic of interdisciplinary research.One of the bottleneck problems is the multi-scenario simulation of urban space.Workflow has the ability to handle complex transactions in heterogeneous environments,and has features such as easy sharing,executable,tasks automation,etc.It is an effective way to achieve repeatable and scalable execution of geographical analysis functions.This paper introduces workflow technology into the multi-scenario simulation of urban population and employment distribution,and based on the KNIME platform,develops a workflow system corresponding to the Garin-Low-ry model.The workflow system includes three modules:data querying and input/output,model calculation,and result analy-sis.According to the core variables of the Garin-Lowry model,this paper sets up a variety of basic employment and traffic network scenarios,compares the spatial structure characteristics of urban population and employment with different employ-ment center patterns under the three ideal urban forms of concentric circles,grid and honeycomb,and simulates the changes of urban population and employment distribution under the local and overall acceleration of road network.The simulation re-sults show that urban form has a weak impact on urban work-residence patterns,but the employment center pattern and road network conditions have a significant impact on the spatial distribution of urban population and employment.The more dispersed the employment centers and the lower the friction coefficient,the more significant the spatial diffusion effect of population.It further confirms the"doughnut effect"and"ribbon hypothesis"proposed in urban science,and also provides a policy simulation tool for urban planning.