Cardinal directions: a comparison of direction relation matrix and objects interaction matrix

How to express and reason with cardinal directions between extended objects such as lines and regions is an important problem in qualitative spatial reasoning (QSR), a common subfield of geographical information science and Artificial Intelligence (AI). The direction relation matrix (DRM) model, proposed by Goyal and Egenhofer in 1997, is one very expressive relation model for this purpose. Unlike many other relation models in QSR, the set-theoretic converse of a DRM relation is not necessarily representable in DRM. Schneider et al. regard this as a serious shortcoming and propose, in their work published in ACM TODS (2012), the objects interaction matrix (OIM) model for modelling cardinal directions between complex regions. OIM is also a tiling-based model that consists of two phases: the tiling phase and the interpretation phase. Although it was claimed that OIM is a novel concept, we show that it is not so different from DRM if we represent the cardinal direction of two regions a and b by both the DRM of a to b and that of b to a. Under this natural assumption, we give methods for computing DRMs from OIMs and vice versa, and show that OIM is almost the same as DRM in the tiling phase, and becomes less precise after interpretation. Furthermore, exploiting the similarity between the two models, we prove that the consistency of a complete basic OIM network can be decided in cubic time. This answers an open problem raised by Schneider et al. regarding efficient algorithms for reasoning with OIM.     

基于灰度共生矩阵对纹理特征的分析

利用灰度共生矩阵对遥感影像中的纹理特征进行分析,了解各特征值在不同纹理的表现。得出灰度共生矩阵对纹理特征的分析。     

A Pedagogic Framework to Link GIS to the Intellectual Core of Geography

Abstract

This paper aims to develop a new pedagogic framework for teaching GIS at the college and university level using Berry's geographic matrix. By synthesizing different schools of thought, this paper argues that GIS education essentially involves two aspects—how to teach about GIS and how to teach with GIS. Berry's geographic matrix can be used to tie these dual aspects of GIS education together neatly. As an abstract representation of geographical phenomena, the geographic matrix embeds all three entities of GIS—location, attribute, time—and thus can help GIS instructors teach about GIS. As a synthesis of geographical approaches, the geographic matrix can assist GIS instructors teach with GIS. This paper demonstrates that GIS is actually an implementation of Berry's geographic matrix. Furthermore, the 10 approaches to geographical analysis, originally proposed by Berry for the geographic matrix, can be executed routinely in a GIS environment. By incorporating Berry's geographic matrix into GIS education, teachers can enable students to surpass technical issues and to appreciate the conceptual and functional linkages between GIS and geography's intellectual core.     

A new assessment model for evacuation vulnerability in urban areas

In the high-speed urbanization process of China, the urban population has been increasing significantly, leading to a high-density aggregation of population. However, the sharp increase in population density has not produced commensurate improvements in the road networks. On the contrary, the population increase induced a serious evacuation vulnerability, which cities experience during various hazards and catastrophic events. Therefore, research on evacuation vulnerability is important to urban planning. To assess the evacuation vulnerability, the optimal and worst scenarios should be considered because all possible evacuation plans occur between these extremes. However, most previous evacuation vulnerability studies are based on the worst-case scenario, only providing an upper bound of a potential evacuation assessment. To provide a more comprehensive theoretical basis for decision-makers to understand the consequences caused by all possible evacuations, this paper proposes an optimal evacuation vulnerability assessment model that provides the lower bound on potential evacuation difficulties. The model is solved by a stepwise spreading algorithm based on Graph Theory. Subsequently, to evaluate the effectiveness of the model, the study adopts the model to assess the evacuation capability of different road network topologies. A comparison with previous research was performed. The model was demonstrated in an application to the South Luogu Alley of Beijing, China. The significance of this paper is that the combination of our model with previous research may provide a more complete theoretical basis for an evacuation vulnerability assessment.     

基于GIS的云南保山小流域土地利用变化研究

随着全球变暖趋势的增强,土地利用变化是全球变化中的重要组成部分。土地利用变化研究尤其是空间变化研究就成为了研究者非常关心的问题。以云南省保山杨柳小流域土地利用变化的实例分析,详细阐述了GIS的空间分析方法及其在土地利用变化研究中的应用。利用转移矩阵研究结果显示:该小流域农地总变化量最大,其次是有林地和荒山,变化最小的是水体和未利用地,有林地和未成林造林地以交换变化为主,水体和居民地净变化为主;从新增的角度来说,农地转化为有林地最具有转换优势,其次是农地转换为荒山;从流失的去向看,牧地转换为农地最具转换优势,其次是农地转换为牧地。     

一种基于GIS的预报降雨栅格动态生成方法初探

中国大部分地区的降雨监测点位布设稀少且分布不均,特别是大区域的降雨监测和预报存在着不准确现象。利用GIS技术,以都江堰市为研究区,结合降雨随海拔变化规律与实测降雨数据,初步建立了降雨随海拔高度变化的二次曲线计算公式和等高线对应转折拐点降雨图层,参考对比自定义降雨矩阵点图层生成的预报降雨栅格效果,最后在基于AE开发的山地平原过渡区土地生态安全预警系统中,依据等高线拐点降雨图层动态生成研究区降雨栅格,作为该系统下预警指标动态监测模块的主要指标因子,初步解决了研究区降雨监测点位少的情况下,全区预报降雨可视化程度低和局部预报准确度不高的问题,有效地提高了降雨预报的准确性和直观性。     

硼酸镁(铝)晶须增强镁基复合材料中界面特性对比研究

对硼酸镁(铝)晶须增强镁基复合材料的界面行为进行了对比研究。对复合材料进行了示差扫描量热分析以及对复合材料中萃取的晶须进行了X射线衍射分析,表明在硼酸镁晶须增强AZ91D镁基复合材料界面无界面反应产物的生成。通过对硼酸镁晶须增强AZ91D镁基复合材料界面的键合状况进行分析和讨论,认为界面的键合是由无反应产物的化学键合、扩散键合及物理键合所组成。另外,根据已有的关于硼酸铝晶须增强镁基和铝基复合材料界面行为的研究结果,分析得出硼酸铝晶须增强镁基复合材料在硼酸铝晶须/AZ91D镁合金界面上的反应产物只有MgO。     

Unmixing magnetic remanence curves without a priori knowledge

Many of the natural materials studied in rock and environmental magnetism contain a mixed assemblage of mineral grains with a variety of different origins. Mathematical decomposition of the bulk magnetic mineral assemblage into populations with different properties can therefore be a source of useful environmental information. Previous investigations have shown that such unmixing into component parts can provide insights concerning source materials, transport processes, diagenetic alteration, authigenic mineral growth and a number of other processes. A new approach will be presented that performs a linear unmixing of remanence data into coercivity based end-members using only a minimal number of assumptions. A non-negative matrix factorization (NMF) algorithm for unmixing remanence data into constituent end-members is described with case studies to demonstrate the utility of the approach. The shape of the end-members and their abundances obtained by NMF is based solely on the variation in the measured data set and there is no requirement for mathematical functions or type curves to represent individual components. Therefore, in contrast to previous approaches that aimed to unmix curves into components corresponding to individual minerals and domain states, NMF produces a genetically more meaningful decomposition showing how a data set can be represented as a linear sum of invariant parts. It has been found that the NMF algorithm performs well for both absolute and normalized remanence curves, with the capacity to process thousands of measured data points rapidly.     

1989-2003年厦门市湿地动态变化分析

通过对厦门市1989年、1993年、1997年TM遥感影像和2003年ETM+遥感影像的解译分析统计,用单一土地利用动态度、转移矩阵等对1989-2003年厦门市湿地动态变化进行了分析,并进行了主要驱动力分析。结果表明:1989-2003年间,由于经济发展、人口增长以及农业生产比较利益的驱动和农业内部结构调整的影响,水库水塘、养殖、滩涂等湿地类型被非湿地侵占;养殖面积从1989年的4230hm2持续增加到2003年的9768hm2,主要是通过占用非湿地、滩涂、盐田和水库水塘增加的;红树林面积大幅度减少,从1989年的84hm2持续减少到2003年的17hm2,主要是由于养殖、非湿地的侵占以及遭受破坏变为滩涂。     

沙漠环境对沙漠公路工程的影响

沙漠地区自然环境严酷，风沙活动对沙漠公路的影响贯彻于各个施工阶段，为获得沙漠工程环境因子及其影响的定量认识，采用二次矩阵方法对公路工程环境影响的程度进行量化评价并提出环境对策。     

市域开发空间区划方法与应用——以南京市为例

主体功能区是近年来各级政府和学术界共同关注的热点。论文以主体功能区规划的理念和原则为指导,将主体功能区划的方法延伸到市域空间尺度,提出城市区域开发空间分区方法及应用模式,将市域发展区划分为优化开发、重点开发、限制开发和禁止开发等四大类。在相关理论及已有研究成果的基础上,对城市开发空间区划的理论模型与方法路径进行探讨。通过空间开发约束、空间开发引导和空间开发强度三方面要素的对空间功能区域综合分析,采用两次两维矩阵的判别方法,并将空间开发引导和空间开发约束先构建二维判别矩阵,得出空间开发的适宜性分类,将空间开发的适宜性结果与现状空间开发强度进行组合判别,从而确定空间开发的功能类型。根据不同类型的功能区域,确定空间未来的利用。同时选取南京为实证研究对象,对理论模型与技术方法的实际应用进行验证,对南京市域进行数据分析,提出南京开发空间分区方案,并依此引导城市空间战略的调整,力求对南京空间秩序的开发、空间方向的拓展、产业布局的调整等具有一定的指引作用。     

正反负矩阵权重分析法在西藏泥石流危险性分区中的应用

介绍了正反负矩阵权重分析法的基本原理和分析过程。结合西藏地区泥石流发育分布规律,建立了泥石流危险性区划判别模型。模型中选取地质构造、地貌和气候条件(包括降水强度、年均地温和冰川水文)为影响因子,同时考虑到研究区内基础资料少的限制,再选取既能表征影响因子强度又能直接获取得因子参数进行研究。通过对各影响因子的分区赋值,利用G IS空间分析技术,对西藏地区泥石流危险性分区进行了研究。结果表明,西藏东南部泥石流危险度最强,从整个西藏地区来看危险等级由东南向西北递减。     

1949—2007年新疆绿洲经济分布格局演变及其机制研究

以新疆绿洲经济空间分布为研究对象,以1949—2007年87个县市人均GDP数据为资料,运用空间概率模型和ArcGIS技术,分析了1949—1978年、1978—1990年、1990—2007年3个阶段新疆绿洲经济分布格局时空演变规律。首先根据人均GDP,把全疆县市分为高水平、中高水平、中低水平和低水平4类经济发展类型,运用马尔科夫链转移矩阵求出新疆各县市在3个阶段转移概率,用ArcGIS把3个阶段空间转移格局可视化。其次构建空间马尔科夫链,分析不同背景区域对4类经济发展类型空间转移的作用,探讨其作用机理。研究发现:①1949—2007年间,以县市为单位的新疆绿洲经济格局空间分布发生了“俱乐部趋同”现象,其中高水平和低水平经济发展类型非常明显,主要动力是新疆绿洲主导经济由原来的农牧业转变成以资源加工为主的第二产业和以行政、交通为主的第三产业。②4类经济发展类型在3个阶段转移方向不同,计划经济期间表现出中低水平经济发展类型向上转移,区域均衡发展政策起到强大作用。在市场经济阶段,经济发展水平相似区域倾向于“俱乐部趋同”,市场“极化”作用明显。区域转移强度不同,相邻层次水平区域转移明显,“跨层次”转移较弱。③绿洲背景区域作用具有选择性和时效性,在计划经济时期,区域背景对高水平、中高水平、中低水平和低水平区域保持原状态起到阻碍作用,而在市场经济时期,对高水平、低水平区域保持原水平起到推动作用,其他规律性不明显。④绿洲经济低水平经济发展类型转移较小,稳定性强,“负马太效应”显著;高水平经济发展类型稳定性差,在不同阶段均发生15%左右的向下转移,表现出经济的脆弱性和低级性。