三维地理信息网络服务的发展现状及思考

随着信息技术的发展和GIS的实际发展需求的增加,GIS逐渐转向了三维地理信息网络服务方向。在满足GIS服务发展需求的基础上,三维地理信息网络服务为空间信息的高效集成的实现作出了重要贡献。本文综述了三维地理信息网络服务的发展情况,并提出了存在的问题及相应的建议,以供参考。     

一种面向服务的应用系统智能组装技术

针对目前GIS应用软件所面临的开发难度大、周期长,更新维护困难、扩展性差等诸多问题,秉承面向服务的设计理念,文章提出了一种智能组装式软件开发方式,研究了实现过程中的4个关键技术:用户需求分析、服务智能匹配、自动化组装和人机协同调整机制,并应用NewMap Plat4软件研制开发了原型系统——智能组装器,实现了应用系统的可视化一键式组装开发,使得系统开发变得简单、快捷,且系统具有良好的扩展性。     

深度卷积神经网络支持下的遥感影像飞机检测

针对YOLOv3算法对小目标检测较差及出现较多漏检的问题,本文提出了一种优化的YOLOv3算法.首先使用K-means算法计算出与数据集相适用的锚框;其次将扩张卷积引入到YOLOv3网络,用来增强网络高层的感受野,改善小目标的检测效果;然后使用深度可分离卷积取代YOLOv3网络残差模块中的普通卷积,可减少计算量,从而得到一种新型卷积神经网络结构;最后在数据集上进行对比试验.结果表明,优化的YOLOv3算法能够检测出更多目标,降低漏检率,相比于YOLOv3算法,其召回率提高11.86%,F1-score提高2.99%.     

FY-3D and FY-3C onboard observations for differential code biases estimation

GPS Solutions - As parameter estimation and statistical testing are often intimately linked in the processing of observational data, the uncertainties involved in both estimation and testing need...     

高精度GPS复测网的形变基准解释

在高精度GPS复测网的平差处理中 ,首先要选择一组已知的、精确的IGS (国际GPS地球动力学服务 )跟踪站为基准 ,并对基准站坐标施加不同的约束 ,这样就产生了不同的参考基准。在深入探讨基于不同约束的GPS网平差的参考基准及意义的基础上 ,文中推导了不同基准之间的转换关系     

Shape Similarity measures of Linear Entities

The essential of feature matching technology lies in how to measure the similarity of spatial entities.Among all the possible similarity measures,the shape similarity measure is one of the most important measures because it is easy to collect the necessary parameters and it is also well matched with the human intuition.In this paper a new shape similarity measure of linear entities based on the differences of direction change along each line is presented and its effectiveness is illustrated.     

Origin and Evolution of Aquitard Porewater in the Western Coastal Plain of Bohai Bay,China

High‐salinity paleowater from low‐permeability aquitards in coastal areas can be a major threat to groundwater resources; however, such water has rarely been studied. The chemical and isotopic compositions of porewater extracted from a 200‐m‐thick Quaternary sedimentary sequence in the western coastal plain of Bohai Bay, China, were analyzed to investigate the salinity origin and chemical evolution of porewater in aquitards. Porewater samples derived at depths shallower than 32 m are characterized by Cl‐Na type saline water (total dissolved solids [TDS], 10.9–84.3 g/L), whereas those at depths greater than 32 m comprise Cl·SO₄‐Na type brackish water (TDS, 2.2–6.3 g/L). Saline porewater is interpreted as evaporated seawater prior to halite saturation, as evidenced by Cl‐Br relationships. Although substantial dilution of saline porewater with meteoric water is supported by a wider Cl^? range and δ²H‐δ¹⁸O covariance, the original marine waters were not completely flushed out. The deeper brackish porewater is determined to be a mixture of fresher porewater and brine groundwater and had a component of old brine of less than 10%, as indicated by a mixing model defined using δ²H and Cl^? tracers. Porewater δ²H‐δ¹⁸O relationships and negative deuterium excess ranging from ?25.9‰ to ?2.9‰ indicate the existence of an arid climate since Late Pleistocene in Tianjin Plain. The aquitard porewaters were chemically modified through water‐rock interactions due to the long residence time.     

Precipitation variability during the past 400?years in the Xiaolong Mountain (central China) inferred from tree rings

We developed the first tree-ring chronology, based on 73 cores from 29 Pinus tabulaeformis trees, for the Xiaolong Mountain area of central China, a region at the boundary of the Asian summer monsoon. This chronology exhibits significant (at 0.01 level) positive correlations with precipitation in May and June, and negative correlations with temperature in May, June and July. Highest linear correlation is observed between tree growth and the seasonalized (April–July) precipitation, suggesting that tree rings tend to integrate the monthly precipitation signals. Accordingly, the April–July total precipitation was reconstructed back to 1629 using these tree rings, explaining 44.7?% of the instrumental variance. A severe drought occurred in the area during the 1630s–1640s, which may be related to the weakened Asian summer monsoon caused by a low land-sea thermal gradient. The dry epoch during the 1920s–1930s and since the late 1970s may be explained by the strengthened Hadley circulation in a warmer climate. The dry (wet) epochs of the 1920s–1930s (the 1750s and 1950s) occurred during the warm (cold) phases of the El Ni?o-Southern Oscillation and the Pacific Decadal Oscillation that are often associated with weakened (strengthened) East Asian summer monsoon. These relationships indicate significant teleconnections operating over the past centuries in central China related to large-scale synoptic features.     

小口径割管器的设计与应用

某盐井施工时,在245．00—270．00m孔段有25m钻具被水泥固结,进行透孔作业时,扫至孔深250．60m时,扫孔用岩心管被扫落的钻杆接头碎块卡住拧断,透孔时发现孔内遗留3．2m断岩心管、钻头等物。根据钻孔结构与遗留钻具的特点．自行设计一种主要由活塞柱、割刀片和复位弹簧组成的小口径割管器,将水泥固结钻具割断,并将钻具和多种残留管材打捞出孔。从割断后打捞上来的钻杆分析,钻杆切割面光滑、平整,钻杆被完全切透,说明此种割管器设计合理,各部件动作有效。     

跨越断层埋地管线地震反应研究述评

本文论述了跨越断层埋地管线地震反应研究工作概况,包括理论研究和实验研究的进展,并介绍了不同情况下采用的研究方法和建立的相应的研究模型,通过对数据结果进行整理分析,得出跨越断层埋地管线地震反应规律。同时,本文还对埋地管线研究中的一些重要参数对研究结果的影响作了详尽的阐述,提出了需进一步研究的问题和今后可能的研究发展方向。