带有区域分裂自适应细化过程的SAR海冰图像分割     

郎文辉  沈杨  昂安  张晰  吴青  杨学志  孟俊敏 《遥感学报》2015,19(5):864-872

受海冰自身特性、成像系统特性和环境因素的影响,合成孔径雷达SAR海冰图像具有非平稳、尺度依赖的空间结构,现有的单马尔可夫随机场MRF模型分割方法只能较好地适应非平稳性,对海冰场景的多尺度结构考虑仍然是全局的。为此,本文提出了一种区域分裂过程与二叉树分层结构自适应更新相结合的单MRF图像分割方法。首先利用单MRF模型的全局迭代权值完成初始区域合并,同时以二叉树形式保护合并过程的记录。所设计的分层合并算法可保证二叉树结构的节点数与场景中的对象尺度具有正相关性。随后的细化分裂并不产生新的区域,只是返回到初始配置。依据场景中不同区域对象的尺度,自适应地调整空间语境模型中的尺度权值,实现区域更新。实验表明,该方法有效提高了带有多尺度结构SAR海冰场景的分割精度。  相似文献   

Mining Trajectory Data and Geotagged Data in Social Media for Road Map Inference   总被引：1，自引：0，他引：1       下载免费PDF全文

Jun Li  Qiming Qin  Jiawei Han  Lu‐An Tang  Kin Hou Lei 《Transactions in GIS》2015,19(1):1-18

As mapping is costly and labor‐intensive work, government mapping agencies are less and less willing to absorb these costs. In order to reduce the updating cycle and cost, researchers have started to use user generated content (UGC) for updating road maps; however, the existing methods either rely heavily on manual labor or cannot extract enough information for road maps. In view of the above problems, this article proposes a UGC‐based automatic road map inference method. In this method, data mining techniques and natural language processing tools are applied to trajectory data and geotagged data in social media to extract not only spatial information – the location of the road network – but also attribute information – road class and road name – in an effort to create a complete road map. A case study using floating car data, collected by the National Commercial Vehicle Monitoring Platform of China, and geotagged text data from Flickr and Google Maps/Earth, validates the effectiveness of this method in inferring road maps.  相似文献   

Magnetic properties of Jiaxian red clay sequences from northern Chinese Loess Plateau and its paleoclimatic significance     

QIANG Xiaoke  AN Zhisheng  LI Huamei  CHANG Hong & SONG Yougui . SKLLQG  Institute of Earth Environment  Chinese Academy of Sciences  Xi’an  China  . Guangzhou Institute of Geochemistry  Chinese Academy of Sciences  Guangzhou  China 《中国科学D辑(英文版)》2005,48(8):1234-1245

Rock magnetism research on eolian deposits from the Chinese Loess Plateau shows that magnetite, maghe- mite and hematite are the main magnetic minerals in loess-paleosol sequences and red clay se-quences[1―8], and finds that the magnetic susceptibility increase is positively correlated to the content of ultra-fine minerals and relatively strong pedogene- sis[7―15]. This offers significant information in studying the Late Cenozoic paleoclimatic history of Chinese Loess Plateau[1,5―8,10―22…  相似文献   

A Peculiar Broad Line Radio Galaxy 1938-155： VLA Observation at 90 cm     

Tao An  Xiao-Yu Hong  Wen-Xia Feng  Jun-Hui Zhao Shanghai Astronomical Observatory  Chinese Academy of Sciences  Shanghai  National Astronomical Observatories  Chinese Academy of Sciences  Beijing Harvard-Smithsonian Center for Astrophysics  Garden Street  MS  Cambridge  MA 《中国天文和天体物理学报》2004,4(6):527-532

We observed 1938-155, a broad line radio galaxy (BLRG), with the Very Large Array (VLA) at 90cm with an angular resolution of 6.8" × 4.0". The source consists of two components separated by 4 arcsec (- 20kpc, for H0 = 65km s-1 Mpc-1, q0 = 0.5) along the SE-NW direction. Both components show steep-spectra with a similar spectral index α - 0.83 ± 0.07 (Sv ∝ v-α). The bright double components are surrounded by a low-brightness cocoon. The radio properties of the two bright components are consistent with the hot spots produced by twin jets. An upper limit of - 0.0008 for the core dominance parameter (R) is inferred, suggesting there is no prominent radio core in the source. Assuming a modest viewing angle 30f77, a jet velocity is estimated - 0.07 c, based on the jet to counter-jet brightness ratio (J). The lower limit in jet speed inferred is consistent with no Doppler beaming effect on the jet. The radio galaxy 1938-155 could be an exceptional BLRG with no prominent radio core or jet.  相似文献   

Model Test Study on Ice Induced Vibration of A Compliant Conical Structure     

黄焱  史庆增宋安 《中国海洋工程》2005,19(3):443-456

1.Introduction Inthedesignofoceanengineeringstructuresforcoldregioncountries,iceloadsarealwaysthe controlloads,andthedesignofice resistingstructuresisoneoftheimportantdesignaspects.Fornat uralseaice,theflexuralstrengthisalwaysonethirdofthecompressivestrength.Soconicalstructures thatcouldinducethebendingfailureoficesheetsarewidelyusedinthedesignsofice resistingstruc tures.Forexample,theplatformKullukintheBeaufortSeaisaninvertedconicalstructure,andan upward downwardbendingconeisusedonplatformJ…  相似文献   

滦河三角洲滨岸沙体的形成和海岸线变迁   总被引：18，自引：1，他引：18  

高善明  李元芳  安凤桐  李凤新 《海洋学报》1980,2(4):102-114

滦河是渤海沿海地区的多沙性河流,每年输入渤海2,670万吨泥沙,主要堆积在河口附近,在波浪作用的参与下,建造了一个发育较快的三角洲平原。据C14测定的年代数据和考古历史资料,全新世以来先后形成五个次一级三角洲堆积体。  相似文献   

大洋和大陆边缘岩石圈有效弹性厚度的研究意义   总被引：4，自引：1，他引：4  

付永涛  李安春  秦蕴珊 《海洋地质与第四纪地质》2002,22(3):69-75

大洋岩石圈有效弹性厚度分布在 (45 0± 15 0 )℃等温面内 ,并且随着加载时岩石圈年龄的增加而增加。因此 ,大洋岩石圈的挠曲刚度强烈地依赖岩石圈的热结构。一些海隆下岩石圈有效弹性厚度的降低 ,可能是岩石圈经历过热活化 ,岩石圈热年龄降低的结果。大西洋一些群岛的岩石圈有效弹性厚度小于理论值 ,则反映了岩石圈结构的不同。在海沟 ,板块的挠曲也是影响岩石圈有效弹性厚度的因素 ,它降低了岩石圈的强度。在被动大陆边缘海陆岩石圈交界处 ,向陆的方向 ,岩石圈弹性厚度比同年龄的大陆或大洋岩石圈的小 ,表明强度明显降低 ;向大洋方向 ,岩石圈的弹性厚度与正常的大洋岩石圈弹性厚度吻合。在活动大陆边缘的挠曲前陆盆地和造山带 ,岩石圈有效弹性厚度变化较大 ,部分地区受先前的岩石圈低强度影响 ,而表现出岩石圈强度的弱化。同时 ,这种方法还广泛地用于大洋中脊岩浆侵位、地幔流动、南太平洋超级海隆的动力学机制、大陆边缘的变形和构造演化、新生岩石圈的力学性质和流变学性质的研究  相似文献   

Determination and control of longshore sediment transport: A case study   总被引：1，自引：0，他引：1  

H. An?l Ari  Yalç?n Yüksel 《Ocean Engineering》2007,34(2):219-233

The fishery harbor of Karaburun coastal village is located at the south west coast of the Black Sea. The significant waves coming from north eastern direction cause considerable rate of sediment transport along 4 km sandy beach towards the fishery harbor in the region. The resulting sediment deposition near and inside the harbor entrance prevents the boat traffic and cause a vital problem for the harbor operations. In order to determine the level and reasons of the sediment transport, the long-term observations of shoreline changes, the long-term statistical analysis of wind and wave characteristics in the region, and sediment properties have been performed. The data obtained from observations, measurements and analysis were discussed. The long-term statistics of deep water significant wave heights for each direction was discussed by comparing the results obtained from different data sources and methods. For shoreline evolution, the numerical study using one-line model was applied to describe the shoreline changes with respect to probable wave conditions. Initial shoreline was obtained from the digitized image in 1996 since there was no previous shoreline measurement of the site. The results were compared using the techniques of remote sensing obtained from sequent images using IKONOS and IRS1C/D satellites.  相似文献   

苏北地区泥岩欠压实现象与油气保存的关系   总被引：2，自引：0，他引：2  

杨芝文  陈安定 《海洋地质前沿》2003,19(3):24-27

泥岩欠压实现象是苏北地区，特别是苏北盆地东台陷下第三系地层中重要的地质特征之一。在对泥岩欠压实现象的研究中发现，东台坳陷的泥岩中压力封闭形成时间早于毛细管封闭的形成时间,而且封闭能力较强，对第三系油气的早期保存起着重要作用。另外，欠压实的存在说明断裂、裂隙系统尚未能打破“暂时”的压力不平衡现象，具有欠压实现象的地层可以作为具有封挡能力的区域性的或圈闭的纵向封隔层。在苏北地区用欠压实表示泥岩层的封挡能力显示：新生界盆地地区和下第三系古、始新统封存条件最为优越；中生界欠压实现象不很普遍，其油气封存条件具有局部性；上古生界欠压实现象较明显，为苏北地区海相中、古生界地层中具有最优越封存条件的层系；志留系高家边组欠压实现象相对较弱。  相似文献   

格网化的位置微博数据抓取与人群信息提取     

雷程程  张岸  齐清文  苏惠敏 《测绘科学》2017,42(2)

空间位置信息通常代表了设备使用人群的地理空间活动特征,客观体现人群活动的时空分布。针对现有的微博数据抓取方法由于普通用户的访问限制易导致采集的目标数据缺失的问题,该文提出了一种目标区域空间划分策略。在数据抓取之前对目标区域实行格网化,进而实现数据的同时抓取。通过统计分析基于网格单元抓取的位置微博数据,从中提取出人群活动信息,结合位置微博数据所在的兴趣点类型,统计分析了位置微博用户的时空分布和活动特征。这种方法缩小了采集区域,可实现并行高效的位置微博抓取,并保证了采集范围的重叠,最大限度地保证采集数据的完整性。  相似文献