Maritime network dynamics before and after international events   总被引：1，自引：0，他引：1  

Zhixiang Fang  Hongchu Yu  Feng Lu  Mingxiang Feng  Meng Huang 《地理学报(英文版)》2018,28(7):937-956

Investigating the influence of international events on global maritime networks is a challenging task that must comprehensively incorporate geographical, political, and maritime sciences. Understanding global maritime network dynamics is an initial and critical step in this investigation. This study proposes an automatic identification system (AIS)-based approach to understanding maritime network dynamics before and after international events. In this approach, a spatiotemporal modeling method is introduced to measure the similarity in shipping trends before and after international events. Then, a spatiotemporal analytic framework is proposed to understand the maritime network dynamics by grouping similar situation, and assessing possible indirect effects within a network. Finally, three case studies of international events, military conflict, lifted economic sanctions, and government elections, were used to investigate the observed network dynamics possibly affected by international events. The results indicate that container, tanker, and bulk shipping between India and its connected countries all declined more than 69% after military conflicts between India and Pakistan in August 2015. Tanker shipping between Iran and the United Arab Emirates increased 51% after economic sanctions on Iran were lifted. Container shipping between Sri Lanka and Singapore, Malaysia, and India increased more than 74% after the general election in Sri Lanka. These investigations demonstrate the feasibility of the proposed approach in assessing the possible effects of international events on maritime network dynamics.  相似文献   

吉林省人口老龄化时空分异特征及成因   总被引：1，自引：0，他引：1  

梅林  郭艳花  陈妍 《地理科学进展》2018,37(3):352-362

本文基于地理信息软件ArcGIS 10.1,选取老年人口系数为人口老龄化指标,运用人口重心模型、空间自相关和半变异函数等分析方法,对吉林省第四次、第五次、第六次人口普查数据进行分析,探讨1990-2010年吉林省人口老龄化时空分异特征,并采用多元线性回归方法解释其形成原因。研究结果表明：①吉林省各县市人口老龄化差异明显,进程加快,重心由西北向东南方向移动,但移动速度减缓;②吉林省人口老龄化存在正的空间自相关性,在空间的集聚呈现先弱后强的变化趋势;③人口老龄化高—高区向东部集聚,低—低区向西部集聚的趋势比较明显;④总体上吉林省人口老龄化空间的结构化分异较为明显,随机性因子引起的空间异质性程度较弱,人口老龄化的空间差异主要体现在东—西方向上;⑤出生率始终是影响吉林省人口老龄化的主要因素,迁出率对人口老龄化发展起关键作用,人均GDP年对人口老龄化呈负相关,城市化率对人口老龄化的推动作用愈发显著。  相似文献   

东北地区资源型城市转型过程中社会—经济—环境协调演化特征   总被引：2，自引：1，他引：1  

陈妍  梅林 《地理研究》2018,37(2):307-318

借鉴协调发展相关理论,构建综合评价资源型城市社会、经济和环境转型的指标体系,利用面板数据回归模型测算2000-2014年系统内各要素对资源型城市协调转型的作用,对东北地区资源型城市转型以来协调发展的时空格局进行分析。研究发现：① 东北地区资源型城市转型协调水平呈现波动式缓慢上升的走势,共出现四次较大幅度的波动,空间上差异性先减弱后加剧,协调程度较高的地区主要集中在辽宁省南部,失调城市分布在黑龙江省北部边缘地区,无论是协调度水平变化或是空间分布上这种“两极”分化的趋势越来越明显。② 东北地区资源型城市协调转型发展总体水平不高,从划分类型看,协调发展型城市在社会—经济—环境各方面作用力均衡较好,对社会服务设施完善等方面投入强于发展调和型城市和失调衰退型城市,钢铁型城市协调转型水平强于石油型城市和冶金型城市,森工型城市表现最弱。③ 第三产业发展、教育、技术、非国营经济、生产生活环境等因素对协调转型的促进作用显著,但历史遗留问题、产业结构升级等仍待进一步解决,同时也对实践创新、体制机制改革提出了高要求。  相似文献   

地震滑坡高分辨率遥感影像识别     

彭令  徐素宁  梅军军  苏凤环 《遥感学报》2017,21(4):509-518

区域性地震滑坡信息获取目前主要通过遥感目视解译和计算机提取,存在主观性强、耗时费力、提取精度低等问题,导致难以满足灾后应急调查、灾情评估等方面的应用需求。采用资源三号、高分一号高分辨率遥感影像,以汶川震区为实验区,在地震滑坡灾害特征分析的基础上,通过多尺度最优分割方法构建多层次滑坡对象,融合光谱、纹理、几何等影像特征和地形特征信息建立多维滑坡识别规则集合,基于高分辨率影像认知模式与场景理解过程提出滑坡分层识别模型,从而实现地震滑坡空间分布及其滑源区、滑移区和堆积区的准确识别。实验区分析结果显示最低识别精度为81.89%,而滑坡的堆积区最容易被分辨,识别方法具有可推广性。研究成果可为灾后应急调查提供技术支撑,并促进国产高分辨率遥感卫星的地质灾害应用。  相似文献   

基于边界反走样算法的地图可视化研究   总被引：3，自引：0，他引：3  

梅洋  李霖  贺彪 《武汉大学学报(信息科学版)》2008,33(7)

在现有反走样算法的基础上提出了一种适合于地图可视化的边界反走样算法,并通过试验对该方法的反走样效果和效率进行了测试,在地图可视化中得到了较好的应用.  相似文献   

基于MRMRF的多光谱纹理影像分割方法   总被引：1，自引：1，他引：0  

刘国英  罗伦才  梅天灿  秦前清 《武汉大学学报(信息科学版)》2008,33(9)

提出了一种新的基于多分辨率马尔可夫场(multiresolution Markov random field, MRMRF)模型的小波域多光谱纹理影像分割方法.该方法采用可变的权重参数连接小波分解的多尺度特征场和标记场,通过直接映射,将上一尺度的分割结果作为下一尺度的初始结果,最细尺度上的分割结果作为算法的最终分割结果.实验表明,本文算法能够降低多光谱纹理图像分割的错误率.  相似文献   

基于PDA的测量机器人自动化网观测软件研究   总被引：1，自引：0，他引：1  

梅文胜  郑勇波  周命端 《测绘信息与工程》2008,33(5)

分析了自动化网观测软件的具体开发过程,介绍了软件系统所实现的主要功能,获得了可靠的观测数据.  相似文献   

柴达木盆地北缘柴页1井中侏罗统大煤沟组页岩储层测井评价     

王胜建  包书景  梅建森  梅岩辉  潘洪峰  汪大明 《地质通报》2016,35(203):260-272

页岩储层测井评价是后期压裂改造工程的基础,通过分析柴页1井常规测井曲线特征,结合特殊测井和岩心样品分析化验数据,综合评价了中侏罗统大煤沟组页岩岩性、物性、地球化学、含气性、可压裂性等特征,获得了储层评价及工程改造参数。柴页1井中侏罗统大煤沟组至少发育128.1m厚的富有机质页岩,具有高伽马、高声波时差、高中子、高电阻、低密度的特点;测井计算有利的富有机质页岩的总有机碳含量介于3.20%~4.20%之间,总含气量介于1.50~4.50m3/t之间,有利页岩层段脆性矿物含量介于45%~75％之间,划分出3个有利层组,第Ⅰ层组和第Ⅱ层组具有杨氏模量高、泊松比低的特点,有利于后期射孔压裂。  相似文献   

土体三轴试验固结过程解析解     

陈志波  王志文  朱俊高  梅国雄 《岩土力学》2016,(4):943-947,956

三轴试验是获取土体强度和应力变形特性的一个重要室内试验手段。三轴试验中,排水固结阶段试样的孔压消散及固结完成情况是非常重要的两个核心要素,它是进行后续剪切试验的基础和依据。基于等应变假设,推导了土体三轴剪切试验排水固结过程的解析解,以用于分析整个排水固结过程的孔压消散和固结完成程度。针对室内三轴固结排水(CD)试验,利用所推导的解析解对其排水固结过程的孔压和固结度进行了验算对比。结果表明,解析解计算得到的固结度和孔压消散曲线与室内三轴剪切试验的相应曲线吻合得较好,说明解析解可应用于三轴剪切试验排水固结过程分析。  相似文献   

A New Progress of the Proterozoic Chronostratigraphical Division   总被引：1，自引：0，他引：1  

MEI Mingxiang  Kyawt Kay KHAING 《《地质学报》英文版》2016,90(4):1097-1121

The Precambrian, an informal chronostratigraphical unit, represents the period of Earth history from the start of the Cambrian at ca. 541 Ma back to the formation of the planet at 4567 Ma. It was originally conceptualized as a "Cryptozoic Eon" that was contrasted with the Phanerozoic Eon from the Cambrian to the Quaternary, which is now known as the Precambrian and can be subdivided into three eons, i.e., the Hadean, the Archean and the Proterozoic. The Precambrian is currently divided chronometrically into convenient boundaries, including for the establishment of the Proterozoic periods that were chosen to reflect large-scale tectonic or sedimentary features(except for the Ediacaran Period). This chronometric arrangement might represent the second progress on the study of chronostratigraphy of the Precambrian after its separation from the Phanerozoic. Upon further study of the evolutionary history of the Precambrian Earth, applying new geodynamic and geobiological knowledge and information, a revised division of Precambrian time has led to the third conceptual progress on the study of Precambrian chronostratigraphy. In the current scheme, the Proterozoic Eon began at 2500 Ma, which is the approximate time by which most granite-greenstone crust had formed, and can be subdivided into ten periods of typically 200 Ma duration grouped into three eras(except for the Ediacaran Period). Within this current scheme, the Ediacaran Period was ratified in 2004, the first period-level addition to the geologic time scale in more than a century, an important advancement in stratigraphy. There are two main problems in the current scheme of Proterozoic chronostratigraphical division:(1) the definition of the Archean–Proterozoic boundary at 2500 Ma, which does not reflect a unique time of synchronous global change in tectonic style and does not correspond with a major change in lithology;(2) the round number subdivision of the Proterozoic into several periods based on broad orogenic characteristics, which has not met with requests on the concept of modern stratigraphy, except for the Ediacaran Period. In the revised chronostratigraphic scheme for the Proterozoic, the Archean–Proterozoic boundary is placed at the major change from a reducing early Earth to a cooler, more modern Earth characterized by the supercontinent cycle, a major change that occurred at ca. 2420 Ma. Thus, a revised Proterozoic Eon(2420–542 Ma) is envisaged to extend from the Archean–Proterozoic boundary at ca. 2420 Ma to the end of the Ediacaran Period, i.e., a period marked by the progressive rise in atmospheric oxygen, supercontinent cyclicity, and the evolution of more complex(eukaryotic) life. As with the current Proterozoic Eon, a revised Proterozoic Eon based on chronostratigraphy is envisaged to consist of three eras(Paleoproterozoic, Mesoproterozoic, and Neoproterozoic), but the boundary ages for these divisions differ from their current ages and their subdivisions into periods would also differ from current practice. A scheme is proposed for the chronostratigraphic division of the Proterozoic, based principally on geodynamic and geobiological events and their expressions in the stratigraphic record. Importantly, this revision of the Proterozoic time scale will be of significant benefit to the community as a whole and will help to drive new research that will unveil new information about the history of our planet, since the Proterozoic is a significant connecting link between the preceding Precambrian and the following Phanerozoic.  相似文献