地理空间传感网融合服务技术与应用     

陈能成  肖长江  杨超  王伟 《地球信息科学学报》2020,22(1):11-20

随着遥感数据网、传感网、物联网和人工智能的发展,逐渐形成空天地海立体化、集成化和一体化的地理空间传感网。地理空间传感网感知资源呈现出多源、异构和分散的特征,面向多层次用户个性化、即时化和智能化应用需求,存在异构资源共享管理、多协议实时接入、时空无缝感知、自动化感知和精准预测等技术挑战。静态地理信息服务由于无法提供鲜活的地理信息,难以满足地理事件的综合监测、决策预警和聚焦应用需求,急需发展地理空间传感网融合服务技术和实时动态地理信息服务平台。本文围绕信息物理网环境下空天地海观测平台的观测高效共享和融合服务问题,提出了传感网观测共享信息模型和点面观测协同无缝重建模型,突破了观测在线接入、集成管理、星地融合、时空预测和聚焦服务等地理空间传感网融合服务关键技术,研制了包含“感—联—知—控”等功能的传感网时空信息网络感知服务系统GeoSensor,介绍了GeoSensor在流域、海洋和城市等典型应用。未来将进一步发展“人—水—城”智能感知认知理论,突破“空天地海人”群智感知、空间智能和认知服务技术,开展长江经济带应用。  相似文献   

老挝北部Sentinel-2 A/B云覆盖适宜阈值界定及其影像获取概率时空差异     

刘怡媛  李鹏  肖池伟  刘影  谢正磊 《地球信息科学学报》2020,22(11):2267-2276

光学卫星影像云覆盖时空特征评估是衡量其作为重要遥感监测数据源的前提。Sentinel-2 A/B影像因其免费获取、多光谱（红边）、更高时空分辨率等优势,已在全球不同尺度陆面植被与生态监测中受到重视。相较于Landsat等同类影像产品,有关Sentinel-2 A/B的云覆盖分析还未见报道。本文利用2016—2018年老挝北部所有5288景Sentinel-2 A/B影像（Granule/Tile）的云覆盖元数据,基于不同云覆盖阈值（0~100%）水平下的影像获取概率差异确定了影像获取概率分析的云覆盖适宜阈值,并揭示了云量特征阈值水平下的影像获取概率时空差异。主要结论如下:① Sentinel-2 A/B影像获取概率分析云覆盖适宜特征阈值为20%（即云覆盖≤20%）,该阈值水平下老挝北部Sentinel-2 A/B影像的逐月累积平均获取概率最高（约27.41%）;② 在20%云覆盖阈值水平下,老挝北部Sentinel-2 A/B影像逐月累积平均获取概率差异在时间上与旱季（11月—次年4月）雨季（5月—10月）的时间分布较为吻合。旱季获取概率约为42.91%,3月概率（50.27%）最大,4月与2月次之,时间上与刀耕火种焚烧与橡胶林落叶特征吻合;雨季相应概率约为11.81%,6月最低（约1.26%）;③ 老挝北部Sentinel-2 A/B影像逐月累积平均获取概率在空间上存在东西差异,旱季西部省域单元（如琅南塔）影像获取概率远高于东部,雨季西部地区影像获取概率则略低于东部地区。本研究既可为后续开展大区及全球Sentinel-2 A/B影像云量分析提供借鉴,也对开展联合国减少森林砍伐和退化排放（UN-REDD）计划引发的土地利用变化如刀耕火种农业演变、橡胶林扩张等遥感监测有指导意义。  相似文献   

中药资源地理国情监测工具集设计与实现     

张春星  霍亮  靖常峰 《测绘与空间地理信息》2017,(2):152-155

目前第四次全国中药资源普查试点工作采集了大量的成果数据,并且成果数据与地理空间位置之间存在天然的联系。本文以中药资源数据的空间属性作为出发点,在中药资源普查成果数据和已有地理国情监测数据的基础上,建立了基础地理数据库、专题地理数据库和中药资源数据库,设计并实现了能够进行中药资源专题分析计算的地理工具集。最后,基于B/S架构完成了中药资源地理国情监测技术平台的构建,验证了地理工具集设计思路的正确性。  相似文献   

Exploring the Spatiotemporal Pattern of Cyberbullying with Yik Yak     

Chengbi Liu  Daniel Sui 《The Professional geographer》2017,69(3):412-423

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.  相似文献   

环境约束下中国城市土地利用效率演变特征分析     

施佳颖  何亚芬 《资源与生态学报(英文版)》2021,12(2):143-154

在经济高质量发展和区域协调发展的背景下,考虑非期望性产出(环境污染),本文利用SBM-undesirable模型测算了中国275个地级市2003–2016年的城市土地利用效率,并通过核密度估计、空间自相关分析探索了城市土地利用效率的时空演变规律。结果表明:(1)2003–2016年间,中国城市土地利用效率整体呈波动上升趋势,但仍处于较低水平,城市土地利用效率均值呈现东、西、中逐渐降低的分布格局;(2)在全国和东中西三大区域,区域差异均不断增大,全国尺度上和东部地区效率值出现了极化趋势;(3)城市土地利用效率呈现较弱的空间正相关,但空间集聚程度不断增强。高-高集聚型区域多分布在东南沿海地区,且不断向中部地区延伸;高-低极化型区域多为中西部地区的省会城市,低-高凹陷型区域零星分布于高值聚集区周边,部分在研究期内转为高值聚集区域;低-低均质型区域主要分布在中西部及东北地区。研究结果认为应加强对城市存量土地的内涵挖潜,强化区域合作机制,因地制宜制定提升土地利用效率的政策是促进城市土地集约节约利用和区域协调发展的有效路径。  相似文献   

基于MODIS数据中国天山积雪面积时空变化特征分析   总被引：1，自引：0，他引：1       下载免费PDF全文

何海迪  李忠勤  张明军 《干旱区地理》2018,41(2):367-374

基于2011-2015年MOD10A2积雪产品和气象数据,通过几何校正、去云预处理,应用归一化差分积雪指数算法等获取中国境内天山山区积雪覆盖面积数据,分析了积雪面积的时空变化特征及与气温降水的关系。结果表明：（1）年内积雪面积呈单峰变化,9月开始积累,次年1月达峰值,3月气温回暖消融加速,至7月最小。春秋季波动较大但没有明显的增减趋势,夏季积雪面积最小,冬季最大且呈减小趋势。（2）2001-2015年积雪覆盖面积整体上呈减少趋势,积雪覆盖率最大值的波动比最小值的波动更加剧烈。（3）积雪覆盖率随着海拔升高而增大,海拔<1 500 m区域积雪覆盖率低于10%,海拔>4 500 m以上区域平均可达70%,为常年稳定积雪区。积雪覆盖率在西北坡最高,南坡最低。（4）年均气温升高是积雪覆盖面积减小的主因,年积雪覆盖面积变化与年降水量变化保持一致的下降趋势。  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   

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   

Eco-compensati on in Guanting Reservoir Watershed Based on Spatiotemporal Variations of Water Yield and Purification Services     

WEN Yihui  LIU Guihuan  WU Rui 《资源与生态学报(英文版)》2018,9(4):416-425

Guanting Reservoir (GR) is one of the most important water sources for Beijing and neighboring regions. Due to water pollution, it was withdrawn from the system to supply Beijing drinking water; however, after a thorough treatment process, GR was made a reserve water source since 2007. To develop a comprehensive and quantitative analysis of water yield and purification services in the GR watershed, this study selected two time periods: the period when GR was withdrawn from the system supplying local drinking water and the period that it has been designated a reserve water source. The InVEST model was used to evaluate the quantities of water yields, and total nitrogen and total phosphorus outputs from 1995 to 2010 Additionally, the spatiotemporal variations of water yield services and water quality purification services in the GR watershed were analyzed. The results showed that water yield services in the GR watershed first weakened and then became stronger, but weakened overall during the years 1995 to 2010. Water yield capacity in the basin decreased from 1.89×109 m³ in 1995 to 1.43×109 m³ in 2010 (a drop of 24.0% in total). Water quality purification services also showed the same tendency. Total nitrogen output decreased from 4028.7 t in 1995 to 3611.4 t in 2010, while total phosphorus decreased from 379.7 t in 1995 to 354.0 t in 2010. Nitrogen and phosphorus purification services were enhanced by 10.4% and 6.8%, respectively. Changes in the climate and land use were the main factors which lead to the changes in the water yield service in the GR watershed. Policies intended to protect water resource have matched the varying trends of water quality purification services during different periods. On one hand, the research results provide a foundation to identify key fields for eco-compensation in the Guanting Reservoir basin. On another hand, the ecosystem service value will increase on the basis of eco-compensation criteria through setting the scenarios of returning farmland to forest and ecological protection. This method directly reflects increases in ecosystem service values that have occurred since measures to protect the ecological environment have been implemented. This method is more persuasive and feasible than using eco-compensation criteria based on regional ecosystem service values determined by land use/ coverage type. It can provide a new way to assess eco-compensation in the Guanting Reservoir basin and other regions.  相似文献   

京津冀城市群水资源开发利用的时空特征与政策启示   总被引：5，自引：2，他引：3  

鲍超  贺东梅 《地理科学进展》2017,36(1):58-67

京津冀城市群是中国在国际经济体系中具有最强竞争力的支撑平台之一,也是中国乃至全世界水安全保障难度最大的地区之一。本文主要以2000-2014年数据为基础,采用泰尔系数、变异系数、曲线分析和空间分级分类分析等方法,揭示了京津冀城市群水资源与用水变化的时空特征。结果显示：①绝大多数城市多年平均水资源总量显著减少,干旱化的长期趋势明显,而且北部、西部城市减少幅度更大;②京津冀城市群水资源极度短缺,空间不均衡性呈现先减小后增大的趋势,而且中部和南部城市水资源开发利用潜力更低,缺水更甚;③绝大多数城市用水总量零增长或缓慢负增长,用水结构以工农业用水比重下降为主要特征,各类用水的空间不均衡性保持相对稳定;④用水效率普遍快速提升,空间分布差异呈现先增大后减小的总体趋势。基于此,建议京津冀城市群实施“以水量城”的城镇化政策和“以水定产”的产业政策,完善水生态补偿政策,落实水资源管理红线政策,实现水资源约束下各城市间经济社会与生态环境的协同发展。  相似文献