基于最邻近时空距离的土地变化过程时空模式分析     

聂拼  梁明  李玉洁  游欣妍  孙晓娟 《地球信息科学学报》2020,22(3):628-637

土地利用/土地覆盖受人类活动和城市的快速扩张的影响发生了巨大的变化,这种变化对生态环境和地表景观的影响极大。土地利用/土地覆盖的变化过程既受自然、经济等多种因素的影响,也是人类活动规律和自然因素制约的外部表征。因此研究土地利用/土地覆盖的变化过程具有重要的意义。土地利用/覆盖变化的监测和分析,在传统的方法中侧重于分别对各个时空快照上土地利用结构的整体差异的研究,割裂了不同快照间土地利用单元在演化过程上的有机联系。本文以序列土地利用数据构成的土地变化过程为核心研究对象,在土地变化过程的最邻近时空距离度量的基础上,开展基于蒙特卡洛随机模拟的土地变化过程的时空聚集性度量,量化分析土地利用变化过程时空聚集模式的显著性。使用淮南市市辖区2008-2017年土地利用数据,选取典型的时空演化类型(任意2年间从"耕地"演变为"草地")进行实证研究,结果表明此类土地变化过程在过去10年呈现出时空聚集模式,但统计上并不显著。本文的研究有利于把握土地利用单元在时空上的演变过程,探查土地利用变化过程中潜在的时空演化模式。  相似文献   

基于规则的高分影像不透水层提取技术研究     

徐成华  马志强  乔晓冬  王军锋  宋雨娇 《测绘与空间地理信息》2017,(10):1-4,7

为满足城市环境评价、城市规划监测、城市水循环评价对城市不透水层检测的需求,本文以国产高分卫星多光谱数据为研究基础,提出了一种新颖的基于规则的高分辨率多光谱影像不透水层提取方法,该方法利用归一化指数模型,融合对象统计特征,制定综合判定规则,可有效提升城市区域不透水层的提取精度。同时利用国产卫星数据,选择了典型的10个城市进行实验验证,取得了良好的效果。该方法可广泛应用于城市外轮廓提取、城市环境评估、城市扩展评估等研究领域。  相似文献   

中国页岩气成藏和潜在产能与对环境的污染分析   总被引：5，自引：2，他引：3  

滕吉文  刘有山 《中国地质》2013,40(1):1-30

基于当今化石能源的需求还在扩展,它的紧缺势态波及全球,而中国的确需要更多的页岩气。为此,非常规油、气能源,特别是页岩油、气的勘探、开发和利用就必然地提上了社会进步和经济发展的议程上,并得到世界各个国家的高度重视。因此,页岩油、气现已成为中国能源界和科技界及政府部门的热门话题。在经过了一段时间的"热炒"和依据尚不充分的评估后,本文通过对中外有关资料的分析和讨论认为,(1)必须在了解世界各国、特别是北美页岩油、气赋存与开发的条件下,独立自主地、依据充分地认识中国页岩的分布状态和页岩气的潜能;(2)在理解其他国家页岩属性、页岩气前景和勘查及储存背景下,在中国必须较全面的进行页岩和页岩气存储的地球物理勘探,并选择远景好的典型地区进行示范性研究与探索;(3)厘定页岩气的开采过程与条件及其对环境的污染程度和多个国家对开发页岩气质疑的核心;(4)集理念与实践认识综合制定研究中国页岩气切实可行的方案与怎样发展的路线图;(5)中国目前尚不宜大力投入和急于实施对页岩气的开采,其前景不容过于乐观。  相似文献   

Evaluating representation and scale error in the maximal covering location problem using GIS and intelligent areal interpolation     

Robert G. Cromley  Jie Lin  David A. Merwin 《International journal of geographical information science》2013,27(3):495-517

A common problem in location-allocation modeling is the error associated with the representation and scale of demand. Numerous researchers have investigated aggregation errors associated with using different scaled data, and more recently, error associated with the geographic representation of model objects has also been studied. For covering problems, the validity of using polygon centroid representations of demand has been questioned by researchers, but the alternative has been to assume that demand is uniformly distributed within areal units. The spatial heterogeneity of demand within areal units thus has been modeled using one of two extremes – demand is completely concentrated at one location or demand is uniformly distributed. This article proposes using intelligent areal interpolation and geographic information systems to model the spatial heterogeneity of demand within spatial units when solving the maximal covering location problem. The results are compared against representations that assume demand is either concentrated at centroids or uniformly distributed. Using measures of scale and representation error, preliminary results from the test study indicate that for smaller scale data, representation has a substantial impact on model error whereas at larger scales, model error is not that different for the alternative representations of the distribution of demand within areal units.  相似文献   

Sensitivity of disease cluster detection to spatial scales: an analysis with the spatial scan statistic method     

Meifang Li  Jianfeng He  Tao Liu 《International journal of geographical information science》2013,27(11):2125-2152

ABSTRACT

The spatial scan statistic method has been widely used for detecting disease clusters. Its results may be affected by scales, including the aggregation level of the input data and the population threshold used in the detection. Previous studies offered inconsistent findings, and few had considered both types of scales at the same time. Using 24 simulated datasets and two real disease datasets, we investigated the method’s sensitivity to the two types of scales. We aggregated the individual-level data into areal units of three levels, including county, town, and a 900 m grid. We detected clusters with three population thresholds, including 10%, 25%, and 50%. We used two measurements, distance between cluster centres and the Jaccard index, to quantify the consistency of clusters detected with different scale settings. We find: (1) the method is not greatly sensitive to the data aggregation level when the cluster is strong and in a place with high population density; (2) the method’s sensitivity to the population threshold is determined by the actual size of the true cluster; and (3) a regular grid with fine resolution is advantageous over the subjectively defined areal units. The process and findings may have broader meanings to similar spatial analyses.  相似文献   

Significance of particle interaction to the modelling of cohesive sediment transport in rivers     

Heinz Bungartz  Susanne C. Wanner 《水文研究》2004,18(9):1685-1702

Aggregation processes of fine sediments have rarely been integrated in numerical simulations of cohesive sediment transport in riverine systems. These processes, however, can significantly alter the hydrodynamic characteristics of suspended particulate matter (SPM), modifying the particle settling velocity, which is one of the most important parameters in modelling suspended sediment dynamics. The present paper presents data from field measurements and an approach to integrate particle aggregation in a hydrodynamic sediment transport model. The aggregation term used represents the interaction of multiple sediment classes (fractions) with corresponding multiple deposition behaviour. The k–ε–turbulence model was used to calculate the coefficient of vertical turbulent mixing needed for the two‐dimensional vertical‐plane simulations. The model has been applied to transport and deposition of tracer particles and natural SPM in a lake‐outlet lowland river (Spree River, Germany). The results of simulations were evaluated by comparison with field data obtained for two levels of river discharge. Experimental data for both discharge levels showed that under the prevailing uniform hydraulic conditions along the river reach, the settling velocity distribution did not change significantly downstream, whereas the amount of SPM declined. It was also shown that higher flow velocities (higher fluid shear) resulted in higher proportions of fast settling SPM fractions. We conclude that in accordance with the respective prevailing turbulence structures, typical aggregation mechanisms occur that continuously generate similar distribution patterns, including particles that settle toward the river bed and thus mainly contribute to the observed decline in the total SPM concentration. In order to determine time‐scales of aggregation and related mass fluxes between the settling velocity fractions, results of model simulations were fitted to experimental data for total SPM concentration and of settling velocity frequency distributions. The comparison with simulations for the case of non‐interacting fractions clearly demonstrated the practical significance of particle interaction for a more realistic modelling of cohesive sediment and contaminant transport. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

建筑物合并的Delaunay三角网分类过滤法     

郭沛沛  李成名  殷勇 《测绘学报》2016,45(8):1001-1007

建筑物面合并的方法是大比例尺地图综合研究的重要内容之一,本文提出了一种借助三角网进行建筑物合并的方法:针对约束Delaunay三角网中三角形的形态特征,提出了6种度量参数,依据这些参数进行排除和修复筛选操作;然后自动识别保留下来三角形的外轮廓作为建筑物之间的桥接部分,并对其进行直角化处理;接下来通过桥接部分和建筑物面的融合实现建筑物的合并,同时保持其直角化特征。最后,以多样性的实际数据进行实际处理,验证了该方法的正确性和高效性。  相似文献   

基于蚁群算法的土地利用(图)图斑合并方法     

杨志龙 《测绘与空间地理信息》2016,(2):210-212

很多地图综合问题可以应用优化算法解决,土地利用(图)图斑合并也可以看作是一个优化问题。本文提出了基于蚁群算法的土地利用(图)图斑合并方法。实验结果表明,基于蚁群算法的图斑合并方法优于普通的迭代方法,该方法使综合后各地类面积变化较小且图斑紧凑性较好,是解决土地利用(图)图斑合并问题的一条可行之路。  相似文献   

基于区域划分的多线程并行时空聚集查询方法     

廖帅  陈荦  李军  熊伟  吴秋云 《地理信息世界》2015,(3)

现有的时空数据库能够支持对大规模移动对象数据的时空聚集查询。但移动对象数据量巨大,且目前多采用单线程进行查询计算,其查询速度无法满足应用需求。由于时空聚集查询具有良好的可并行性,提出了一种基于区域划分的多线程并行时空聚集查询方法。该方法在服务器端对时空域进行格网划分,形成多个时空立方体,采用多线程并行的技术方法在每个时空立方体上进行时空聚集查询,最后将查询结果整合。通过对真实数据集进行的实验分析,该方法在查询速度上有明显提升。  相似文献   

序列比例尺地图缩编中建筑物综合算法     

刘洋  兰泽英 《测绘科学》2015,(10):161-166

针对在序列比例尺地图综合中较少涉及如何构建面向大规模工程化应用的、顾及不同居民地分布特征的建筑物综合算子的现状,该文以广州地区为例,从纵横两条线开展。纵向上,对建筑物随尺度变换依次从单幢房屋向建筑群组、建筑区域、街区转换过程中涉及的综合操作和关键算子进行研究;横向上,主要研究同一尺度转换过程中顾及空间分布特征的建筑物多边形分组合并方法,基于"分而治之"的思想对城区、城中村、郊区等三种典型样本设计综合算子。该文设计的算子兼顾了适用性和效率,在广州地区序列比例尺空间数据库快速构建中得到了应用。  相似文献