Incorporating spatial interaction patterns in classifying and understanding urban land use

Land use classification has benefited from the emerging big data, such as mobile phone records and taxi trajectories. Temporal activity variations derived from these data have been used to interpret and understand the land use of parcels from the perspective of social functions, complementing the outcome of traditional remote sensing methods. However, spatial interaction patterns between parcels, which could depict land uses from a perspective of connections, have rarely been examined and analysed. To leverage spatial interaction information contained in the above-mentioned massive data sets, we propose a novel unsupervised land use classification method with a new type of place signature. Based on the observation that spatial interaction patterns between places of two specific land uses are similar, the new place signature improves land use classification by trading off between aggregated temporal activity variations and detailed spatial interactions among places. The method is validated with a case study using taxi trip data from Shanghai.     

Evaluation on the accuracy of digital elevation models

1 IntroductionDigital elevation model (DEM) is digital representation of relief. It is one of the most important components in the database of GIS. At present, DEM is playing a key role in the field of survey and mapping, remote sensing and almost all the terrain related geographical analyses. DEM can be grouped into regular grids (raster) and triangulated irregular networks (TIN). Both have their advantages and disadvantages in application. It is generally believed that grid DEM will …     

峨口铁矿高陡边坡稳定性三维模型试验研究

据计算, 峨口铁矿边坡如增加1坡角可减少剥离量5684万吨, 节约经费1.7亿元。在地质调查基础上, 应用三维物理模型对峨口铁矿边坡进行了设计最终边坡角开挖试验, 加陡边坡角以及陡帮强采试验研究, 以进一步验证矿山原设计最终边坡角的合理与否。     

一次飑线过程的闪电活动特征

结合地闪定位资料和TRMM卫星LIS观测的总闪电资料对一次飑线过程闪电活动进行分析,结果如下:这次飑线过程的正地闪超过了负地闪,占地闪的54.7%.在系统发展的初始阶段全部为正地闪;在系统的快速发展阶段地闪频数明显增大,正地闪比例很高,均在75%以上.在系统成熟至减弱阶段,地闪频数开始下降,而正地闪比例下降,负地闪的比例却越来越大,并占据支配地位.正地闪发生在线对流区(即强回波区内或附近),负地闪发生在层状云区.正地闪并不对应于主上升气流区而是紧邻上升气流区的后部.该雷暴云内闪电活动非常频繁,云地闪比例高达26.1:1.降雹和地面大风区位于正地闪密集区内,地闪频数峰值对应于地面大风阶段.     

基于ONDPI的海岸养殖池塘遥感影像提取研究

以Sentinel-2、Landsat-8卫星影像为数据源,以海岸养殖池塘为研究对象,针对养殖池塘的特点,提出了基于归一化差异池塘指数(NDPI)的面向对象结合法(ONDPI)。并以天津市某一海岸养殖区为例,与传统的水体指数结合直方图阈值分割法进行对比实验。实验表明ONDPI能够对遥感影像中的海岸养殖池塘进行有效提取,提取精度达到95%以上,优于其他方法,能够为海岸池塘养殖的规划管理提供参考数据。     

芦山地震前后龙门山断裂带南段视应力研究

利用四川台网数字地震记录资料,计算了2008年汶川地震之后、2013年芦山地震之前5年内,龙门山断裂带南段ML3.0级以上地震视应力随时间的变化,以及芦山M7.0级地震序列的视应力值及其时空分布特征.结果表明：①从芦山地震之前1年的时间开始,龙门山断裂带南段有视应力的上升过程;②芦山地震余震序列视应力存在几次比较突出的视应力与震级相关性的被打破以及视应力的突降异常,且在震后3个小时之后,视应力即有明显下降的过程;③从归准化的芦山地震序列视应力σapp的空间分布来看,视应力高值区域分布在主震的西南方向和整个余震区东南边缘,并且这两个高视应力区正好分布在该断层面与华南地块紧密接触的边缘;④主震西侧有一片视应力相对较高的区域;⑤主震以北区域的视应力则相对较低.     

船舶破舱浮态方程求解范围研究

在计算船舶的破舱浮态时,常存在一些极端情况以至于迭代计算过程无法正常收敛求解.为了在计算中预先判断浮态方程是否有解,基于船舶倾覆的原理,预估了破舱浮态方程的有解范围,以及船舶可以承受的最大损失浮力,对求解浮态方程的迭代方法及其计算模型有参考价值.     

海相遗迹学的成就、问题与展望

海相遗迹学经历了博物学者时代、藻类时代、大辩论时代、黎明时代,目前正处于现代遗迹学时代。海相遗迹学发展历程中的里程碑事件包括:博物学者对遗迹化石的初步研究、遗迹化石真实属性的确立、德国森根堡海洋研究所的建立、遗迹化石的行为习性分类,以及遗迹相、遗迹组构等重要概念的提出和发展。在系统回顾总结海相遗迹学成就和问题的基础上,着重展示了海相遗迹学发展的3个方向:遗迹化石三维形态重建与形态发生模拟,综合遗迹分类学以及微观手段的运用。海相遗迹学在诠释遗迹化石所反映的生物行为习性以及不同尺度生物—环境相互作用与协同演化等方面具有重要意义。     

Optimizing precipitation station location: a case study of the Jinsha River Basin

Precipitation stations are important components of a hydrological monitoring network. Given their critical role in rainfall forecasting and flood warnings, along with limited observation resources, determining the optimal locations to deploy precipitation stations presents an important problem. In this paper, we use a maximal covering location problem to identify the best precipitation station sites. Considering the terrain conditions and the characteristics of a rainfall network, the original maximal covering location model is modified with the introduction of a set of additional constraints. The minimum density requirement is used to determine a precipitation station’s coverage range, and three weighting schemes are used to evaluate each demand object’s covering priority. As a typical mountainous watershed with high annual precipitation, the Jinsha River Basin is selected as the study area to test the applicability of the proposed method. Results show that the proposed method is effective for precipitation station configuration optimization, and the model solution achieves higher coverage than the real-world deployment. Compared with the commercial solver CPLEX, a genetic algorithm-based heuristic can significantly reduce the computation time when the problem size is large. Several deployment strategies are also discussed for establishing the optimal configuration of precipitation stations.