A partitioned and asynchronous cellular automata model for urban growth simulation     

Xinli Ke  Lingyun Qi  Chen Zeng 《International journal of geographical information science》2016,30(4):637-659

Cellular automata (CA) models are used to analyze and simulate the global phenomenon of urban growth. However, these models are characterized by ignoring spatially heterogeneous transition rules and asynchronous evolving rates, which make it difficult to improve urban growth simulations. In this paper, a partitioned and asynchronous cellular automata (PACA) model was developed by implementing the spatial heterogeneity of both transition rules and evolving rates in urban growth simulations. After dividing the study area into several subregions by k-means and knn-cluster algorithms, a C5.0 decision tree algorithm was employed to identify the transition rules in each subregion. The evolving rates for cells in each regularly divided grid were calculated by the rate of changed cells. The proposed PACA model was implemented to simulate urban growth in Wuhan, a large city in central China. The results showed that PACA performed better than traditional CA models in both a cell-to-cell accuracy assessment and a shape dimension accuracy assessment. Figure of merit of PACA is 0.368 in this research, which is significantly higher than that of partitioned CA (0.327) and traditional CA (0.247). As for the shape dimension accuracy, PACA has a fractal dimension of 1.542, which is the closest to that of the actual land use (1.535). However, fractal dimension of traditional CA (1.548) is closer to that of the actual land use than that of partitioned CA (1.285). It indicates that partitioned transition rules play an important role in the cell-to-cell accuracy of CA models, whereas the combination of partitioned transition rules and asynchronous evolving rates results in improved cell-to-cell accuracy and shape dimension accuracy. Thus, implementing partitioned transition rules and asynchronous evolving rates yields better CA model performance in urban growth simulations due to its accordance with actual urban growth processes.  相似文献   

基于工业用地扩展的长沙城市空间演变与优化     

刘路云  郑伯红 《地域研究与开发》2015,(4)

以工业园区形式为主的工业用地扩展对城市空间演变产生着深刻影响。利用长沙市1949—2013年的城市用地资料,通过计算城市与工业的用地扩展强度指数、等距扩散缓冲强度峰值、重心轨迹、形状紧凑度与空间效率等城市空间衡量指标,分析工业用地扩展的时间特征,揭示工业用地扩展引导城市空间发展由内向填充走向外向扩展、空间模式由单中心走向多中心、空间结构由圈层走向轴向、空间联系由松散走向紧凑等规律,并从总体规划层面提出相应的城市空间优化策略,引导工业用地的合理规划。  相似文献   

Fisher判别及自动获取元胞自动机的转换规则   总被引：6，自引：0，他引：6  

刘小平  黎夏 《测绘学报》2007,36(1):112-118

提出一种基于费歇尔(Fisher)判别和离散选择模型相结合来自动获取地理元胞自动机转换规则的方法。CA的核心是如何定义转换规则,但目前主要是采用启发式的方法来定义转换规则,受主观因素影响较大。本模型结合离散选择模型,通过对Fisher判别方法进行改进,可以成功搜索最佳分隔单元发展和不发展的变量组合,自动确定模型参数值。与常用的Logistic回归模型进行对比分析,结果表明,所提出的方法具有更高的模拟精度,转换规则有着清晰的物理意义。此外,本模型在模拟多类复杂的土地利用变化时可能更具有优势。  相似文献   

基于修正阻尼的土体非线性模型及其在Abaqus中的实现     

王永光  梁建文  巴振宁 《岩土力学》2023,(8):2287-2296

地震等随机循环荷载作用时,常需定义较为复杂的加卸载准则(如扩展Masing准则)来描述土体应力-应变滞回曲线,导致求解过程中需预留大量的状态变量,不便于编程实现;同时,现有Masing模型及其改进模型大多仅对动剪切模量曲线进行拟合,还鲜有考虑对阻尼比曲线的拟合。针对以上两个问题,构建了基于修正阻尼的不规则加卸载准则。该准则克服了上大圈准则需要记忆所有转向点的问题,只需要记忆当前转向点和历史最值,记忆量大大减小;同时该准则能同时考虑动剪切模量和阻尼比曲线,达到了修正阻尼比的目的。基于Matasovic骨架曲线,结合提出的加卸载准则,提出了土体非线性模型并将其开发于Abaqus软件中,通过求解Mississippi湾场地地震反应,并与Deepsoil软件和Davidenkov-Chen-Zhao(DCZ)模型计算得到的场地地震反应结果进行对比分析,验证了所提不规则加卸载准则的正确性。同时,对日本KiK-net强震台网的KSRH10场地进行了地震反应分析,并与加速度时程记录及其谱加速度进行比较,验证了所提模型的适用性。  相似文献   

基于车载LiDAR点云的车辆目标自动检测     

胡舒  王树根  王越  李欣 《地理空间信息》2021,19(3):10-13,17

以武汉市三环线内主要道路夜间停车调查项目为背景,利用车载三维激光扫描技术获取了武汉市三环线内夜间某道路沿线的点云数据,提出了一种基于知识规则的车辆目标自动检测方法。该方法首先采用基于欧式距离分割的聚类方法将点云分割为簇,再分析车辆目标的点云特征和空间几何特征等相关特点,然后建立车辆目标检测的知识规则,最后根据知识规则实现车辆目标的自动检测。实测数据的实验表明,该方法的自动检测准确率为88.10%,证明了其有效性。  相似文献   

Analysis of a large inter-basin water transfer system in India / Analyse d’un grand système de transfert d’eau inter-bassins en Inde     

《水文科学杂志》2013,58(1)

Abstract

Abstract Inter-basin transfer of water in India is a long-term option to correct the spatial and temporal mismatch of water availability and demand, largely owing to the monsoon climate. This paper is concerned with analysis and preliminary design of a large inter-basin water transfer system in peninsular India. The system covers four major basins and involves operation of 13 major structures. The study was carried out in three stages. First, the surface water deficit in each basin was estimated. Then the net deficit was worked out by considering the availability of groundwater. Finally, the link systems were planned to transfer the amount of water needed to meet the demands with desired reliability.  相似文献   

Optimization and simulation of reservoir operation with sediment evacuation: a case study of the Tarbela Dam,Pakistan     

Noor M Khan  Tawatchai Tingsanchali 《水文研究》2009,23(5):730-747

Many reservoirs around the world are being operated based on rule curves developed without considering the evacuation of deposited sediment. Current reservoir simulation and optimization models fall short of incorporating the concept of sustainability because the reservoir storage losses due to sedimentation are not considered. This study develops a new model called Reservoir Optimization‐Simulation with Sediment Evacuation (ROSSE) model. The model utilizes genetic algorithm based optimization capabilities and embeds the sediment evacuation module into the simulation module. The sediment evacuation module is implemented using the Tsinghua university flushing equation. The ROSSE model is applied to optimize the rule curves of Tarbela Reservoir, the largest reservoir in Pakistan with chronic sedimentation problems. In the present study, rule curves are optimized for maximization of net economic benefits from water released. The water released can be used for irrigation, power production, sediment evacuation, and for flood control purposes. Relative weights are used to combine the benefits from these conflicting water uses. Nine sets of rule curves are compared, namely existing rule curves and proposed rule curves for eight scenarios developed for various policy options. These optimized rule curves show an increase of net individual economic benefits ranging from 9 to 248% over the existing rule curves. The shortage of irrigation supply during the simulation period is reduced by 38% and reservoir sustainability is enhanced by 28% through increased sediment evacuation. The study concludes that by modifying the operating policy and rule curves, it is possible to enhance the reservoir's sustainability and maximize the net economic benefits. The developed methodology and the model can be used for optimization of rule curves of other reservoirs with sedimentation problems. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

石家庄市水环境中微量有机物的污染规律研究     

谷宁 《地理与地理信息科学》2002,18(2):85-87

利用色谱 -质谱联机分析技术 ,结合现场调查 ,研究了石家庄市地表水环境中微量有机物的污染分布规律 ,可为城市水源保护提供科学依据  相似文献   

多级变刚度滞变耗能的设计思想和可行性实验研究   总被引：3，自引：0，他引：3  

王焕定  张永山等 《地震工程与工程振动》2001,21(4):154-158

本文提出了一种多级变刚度滞变耗能器，讨论了其设计的基本思想，并进行了初步的试验研究。结果表明，不管是增刚度型还是减刚度型多级变刚度耗能器均具有很好的滞变耗能能力，可以应用于被动自适应（或称为智能）控制。  相似文献   

数字仪与模拟仪地震处理的对比分析及近震走时表的修改     

杨广华 《高原地震》2001,13(3):49-56

利用都兰地震台数字地震仪记录资料，在地震处理中使用修改后的走时表，可以实现从模拟到数字的顺利过渡，更好的使用数字化食品进行地震观测。通过传递函数仿真计算震级的对比以及走时表修改后与修改前震中距的对比分析，找出了两的差异和结合点。  相似文献