多层次格网模型的近邻指数聚类生态区划算法与实验——以新疆北部地区区划为例

在综合考虑气候、植被、地貌等凶素的基础上,提出一种基于多层次格网模型的最近邻指数-模糊聚类生态区域划分算法(Nearest Neighbor Index Fuzzy clustering,NNI-FIC).该算法采用"自下而上"的方式,首先,利用离散格网单元之间的严格相似性形成区划的核心分区;然后,通过最近邻指数统计分...     

基于聚类分析的边坡稳定性研究

在边坡稳定性分析中,滑面搜索方法对于得到边坡的稳定性系数至关重要。现今两种常用的边坡稳定性分析方法,极限平衡法以及强度折减法,可以得到极限应力状态下边坡的潜在滑面。而为了评价边坡在当前应力场下的稳定性,提出一种基于聚类分析概念的滑面搜索方法。这种方法综合考虑了边坡各点的位移以及点安全系数,采用K均值聚类法将具有相近性质的点进行分类,把边坡体分为潜在危险区以及稳定区。潜在危险区的边界即为边坡在当前应力状态下的潜在滑面,并运用矢量和方法计算得到其稳定性系数。采用上述方法对3个算例进行验算,并与极限平衡法以及强度折减法进行对比。结果表明：（1）基于聚类分析的边坡稳定性评价方法具有较好的合理性和可靠性;（2）当边坡处于临界状态附近,通过聚类分析得到的潜在滑面与其他两种方法得到的滑面基本一致;当边坡处于较稳定状态时,当前应力状态下的潜在滑面要比强度折减法得到的滑动带范围要更深更广,但求出的稳定性系数也较高;当存在软弱夹层时,矢量和计算出的滑面更为陡峻,稳定性系数比其他两种方法的结果要小。     

祁连山冰川变化及其脆弱性

Glaciers are a reliable freshwater resource in arid regions of West China and the vulnerability of its changes is closely related to regional ecosystem services and economic sustainable development. Here, we took the Qilian Mountains as an example and analyzed the spatiotemporal characteristics of glacier changes from 1998 to 2018, based on remote sensing images and the Second Chinese Glacier Inventory. We estimated the basic organizational framework and evaluation index system of glacier change vulnerability from exposure, sensitivity and adaptability, which covered the factors of physical geography, population status and socio-economic level. We analyzed the spatial and temporal evolutions of glacier change vulnerability by using the vulnerability evaluation model. Our results suggested that:(1) Glacier area and volume decreased by 71.12±98.98 km² and 5.59±4.41 km³, respectively, over the recent two decades, which mainly occurred at the altitude below 4800 m, with an area shrinking rate of 2.5%. In addition, glaciers in the northern aspect(northwest, north and northeast) had the largest area reduction. Different counties exhibited remarkable discrepancies in glacier area reduction, Tianjuan and Minle presented the maximum and minimum decrease, respectively.(2) Glacier change vulnerability level showed a decreasing trend in space from the central to the northwestern and southeastern regions with remarkable differences. Vulnerability level had increased significantly over time and was mainly concentrated in moderate, high and extreme levels with typical characteristics of phases and regional complexity. Our study can not only help to understand and master the impacts of recent glacier changes on natural and social aspects but also be conducive to evaluate the influences of glacier retreat on socio-economic developments in the future, thus providing references for formulating relevant countermeasures to achieve regional sustainable development.     

基于遥感监测的城市热岛研究进展

全球正经历快速、高强度的城市化,导致城市热岛加剧,并对城市、区域乃至全球许多的生态环境要素直接或间接地产生多方面的影响,与人类福祉密切相关。遥感具有宽覆盖、信息量大、重复观测周期短等优点,已成为地表城市热岛(Surface Urban Heat Island, SUHI)监测广泛采用的一种方法。针对前人相关研究对热红外数据源、监测指标及SUHI时空变化规律尚缺乏系统总结且内容需要更新等问题,本文首先分类评述了SUHI遥感监测所采用的热红外遥感数据源。其次将现有的SUHI监测指标分为土地覆盖类型驱动型、地表温度格局驱动型及两者复合驱动型3类来述评,详细介绍了它们的计算方法、应用案例及优缺点;并从日间变化、夜间变化及昼夜对比的变化3个方面述评了SUHI的年内时空变化规律;归纳了其年际变化规律。最后,依据现有研究结论中相互冲突或尚需深化的地方,指出几个潜在的关键问题或研究方向。     

洪水灾害等级划分的模糊聚类分析

基于模糊数学理论,利用新疆“96．7”特大暴雨洪水典型地州市的灾害资料,选取受灾面积,受灾人口,破坏房屋,直接经济损失四个指标,对灾害等级进行模糊聚类和划分,取得了良好效果。     

黄河三角洲潮沟网络形态特征的时空分异规律及其发育过程

潮沟是陆海生态系统交互作用的主要通道,具有高度的时空动态性。以黄河三角洲新旧河道为界,划分黄河北岸（Ⅰ区）、南岸东（Ⅱ区）、南岸西（Ⅲ区）为对比研究区,选择1998—2018年5个关键时间节点的遥感影像为数据源,利用GIS空间分析功能,定量表征了潮沟发育程度的典型形态特征参数,剖析了黄河改道、湿地恢复工程和外来物种入侵等因子对潮沟发育过程的影响,挖掘潮沟网络的时空演变规律。结果表明：① 潮沟的形态特征具有明显的时空异质性。从1998年黄河改道初期至2004年湿地恢复初期,Ⅰ区各等级潮沟数量大幅减少;由于潮滩淤进和互花米草固滩作用,Ⅱ区潮沟数量、密度、分汊率呈现增长趋势,在2013年互花米草的快速扩张期,潮沟曲率、分汊率明显增大;Ⅲ区潮沟发育的等级、长度、密度最大,等级间的转化频率最高,湿地恢复工程导致低等级潮沟数量、长度明显减少,较强的海洋动力抑制了潮沟曲流的发育。② 黄河改道和侧弯丁坝建设导致平均归槽长度（OPL）增大,潮沟网络的排水效率减少。互花米草的快速扩张使排水效率增大,OPL不断降低;潮沟发育程度Ⅲ区>Ⅱ区>Ⅰ区。③ 潮沟系统由快速变化青年期整体进入缓慢变化中年期,发育状态趋于动态平衡。研究成果有助于了解大范围潮沟的发育过程及演变机制,为沿岸潮滩开发与利用提供科学的决策支撑。     

Exploring the Spatiotemporal Pattern of Cyberbullying with Yik Yak

Cyberbullying is an emerging social issue along with the prevalence of social media. Previous studies have used extensive surveys or firsthand data primarily from conventional social networks¹1 Social media whose users primarily use their real name and provide identifiable information, although some might use pseudonyms (e.g., Facebook and Twitter).View all notes (e.g., Twitter) to study cyberbullying, which often ignores the factor of anonymity and location. Considering the sensitive nature and contagious effect of cyberbullying, a better understanding of the spatiotemporal pattern in cyberbullying is sorely needed to develop effective policies to combat this toxic social behavior. Grounded in the dramaturgy theory and the emerging literature on technoself, this study aims to compare cyberbullying in the anonymous social media (Yik Yak) with the conventional social media (Twitter) and explore its spatiotemporal patterns. A support vector machine is used to help identify records with bullying content. Average nearest neighbor, kernel density, and Ripley's K-function are used to explore the spatiotemporal patterns of cyberbullying behavior. We have found that cyberbullying is more likely to occur in anonymous than conventional social media. We also detected a clustering pattern corresponding to the student population, which can be explained by the dramaturgy theory and recent studies on technoself. In addition to making suggestions to help reduce cyberbullying in the future, this article also sheds light on the need for future studies.     

长江三角洲地区生态足迹的时空动态及其可持续发展分析(英文)

In the urbanizing world,the Yangtze Delta Region (YDR) as one of the most developed regions in China,has drawn a lot of the world’s attention for the remarkable economic development achieved in the past decades.Nevertheless,the rapid economic development was certain to be accompanied by unprecedented consumption and loss of natural resources.Therefore,the analysis of the ecological situation and driving factors of environmental impact was of great significance to serve the local sustainable development decision-making and build a harmonious society.In this paper,the ecological footprint (EF) was taken as the index of the ecological environmental impact.With the help of Geographic Information System (GIS),we studied the spatiotemporal change of ecological footprint at two scales (region and city) and assessed urban sustainable development ability in YDR.Then we discussed the driving factors that affected the change of ecological footprint by the Stochastic Impacts by Regression on Population,Affluence,and Technology (STIRPAT) model.The results showed that increasing trends of regional ecological footprint during 1998-2008 (1.70-2.53 ha/cap) were accompanied by decreasing ecological capacity (0.31-0.25 ha/cap) but expanding ecological deficit (1.39-2.28 ha/cap).The distribution pattern of ecological footprint and the degree of sustainable development varied distinctly from city to city in YDR.In 2008,the highest values of ecological footprint (3.85 ha/cap) and the lowest one of sustainable development index (SDI=1) in YDR were both presented in Shanghai.GDP per capita (A) was the most dominant driving force of EF and the classical EKC hypothesis did not exist between A and EF in 1998-2008.Consequently,increasing in ecological supply and reducing in human demand due to technological advances or other factors were one of the most effective ways to promote sustainable development in YDR.Moreover,importance should be attached to change our definition and measurement of prosperity and success.     

基于MST聚类的空间数据离群挖掘算法

空间离群是指空间邻域中属性特征值明显不同于其他对象的空间对象,空间数据离群挖掘能为人们提供很多有趣的信息,但空间数据具有复杂的拓扑关系、方位关系和度量关系等空间特征,传统的面向事务型数据库的离群挖掘算法并不适用于空间数据库。本文提出了基于MST(Minimum Spanning Tree,最小生成树)聚类的空间数据离群挖掘算法(SOM);有机结合了最小生成树理论与密度的方法,既体现了空间离群的局部特性,又体现了空间离群的孤立程度。该算法通过MST维护空间数据的基本空间结构特征,通过打断MST中最不一致的边形成MST聚类,不仅具有密度的聚类方法能够聚集非球状簇和分布不均的数据集的特点,而且聚类结果不依赖于用户参数的选择,因此,离群挖掘结果更合理。最后,通过实例数据,验证了该算法的有效性,它适用于大规模空间数据集的离群挖掘。     

水文地质分区中的模糊聚类系数法

利用隶属函数构造模聚类系数，给出了一种新的分区方法。运用此方法对水文地质进行分区可大大降低了计算量，并且避免了一些主观因素，该方法的关键是确定隶属函数，可以通过计算机的模拟计算解决。