上海城市用地扩展强度、模式及其空间分异特征

基于多时段TM遥感影像资料,通过有关城市扩展度量指标和网格样方法等空间分析手段的综合应用,论文对上海地区城市扩展规模、强度和空间分异特征进行了研究,结果表明:①上海市区各时期城市用地扩展相对集中于宝山-闵行、嘉定-浦东等方向,并分别构成城市扩展的南北轴向和东西轴向,不同时期各轴向城市用地扩展性质和强度有明显差异,从而使各时期城市扩展表现为以城镇用地为主(1987～1990)到城镇用地与工业开发区并存(1990～1995)以及以工业开发区扩展为主(1995～2000)的形式;②整个上海地区城市化扩展模式在不同时期也发生了很大变化,由较简单的以中心市区及周边区域为主的“单核扩展”为主的模式,逐渐转变为较复杂的包括中心城区、卫星城、郊区城镇以及交通干道等周边区域的“多核扩展”和“点—轴扩展”模式,整个区域城市网络体系发育得更为完善,城市土地利用的功能也由简单趋于复杂和多元化;③从城市土地利用扩展的两种类型看,城镇用地与新开发区的扩展规模和速度及对城市土地利用扩展的贡献率等数量特征各时期存在着极为显著的差异。

基于地理信息系统的城市扩张分析——以郑州市为例

以郑州市为例,通过使用G IS空间分析功能,采用网格样方法对郑州市建国以来的城市土地利用扩展的空间变化特征进行分析,分析其扩张的基本特征,探究其扩展的动力因素,揭示城市发展演化规律,能够为城市规划和管理提供依据,为以后的建设提供借鉴。

Developing Spline Based Overset Grid Assembling Approach and Application to Unsteady Flow Around a Moving Body

Overset or Chimera grid approach is one of methods to cope with complex geometries. A spline based overset grid assembling system has been developed. The system is based on structured grid approach and covers comprehensive features for overset assembling, i.e., grid generation, grid modification, and computing Domain Connectivity Information （DCI） for overset interpolation. Ferguson spline curve is used to compute curves through grid points and cell centers for trimming grids and computing DCI robustly and accurately. Flow simulation around Kriso Container Ship （KCS） with jointed grids shows good continuity of flow field between the grids. The overset grid assembling is enhanced to unsteady problem as dynamic overset approach coupled with a solver which also has been developed in National Maritime Research Institute, Japan. Computed results for pitchup spheroid are compared with measured data and show good agreement in unsteady force acting on the spheroid. It is confirmed that the system has capability to simulate flow field around jointed grids and unsteady flow with dynamic overset assembling approach practically.