灰色预测模型在地面沉降中的应用     

吕传振  安动动 《测绘与空间地理信息》2021,44(3):73-75

城市地面沉降已经成为城市发展的严重制约因素,很多城市都在积极采取控制沉降的措施.地面沉降趋势的预测可为地面沉降防控提供数据参考.本文基于天津某地区沉降监测数据,采用灰色理论建立GM(1,1)模型对沉降趋势进行预测.结果 显示,利用灰色模型预测地面沉降具有较高的精度,能够在地面沉降的预测研究中发挥作用.  相似文献   

"3S"技术在城市"两违"动态监测中的应用     

郑琎琎  傅俏燕  陈君颖  李俊杰  吕争  姜涛 《测绘与空间地理信息》2021,44(7):154-158

为解决城市违法建设和违法占地人工巡查耗时费力,难以及时、动态地进行监测的问题,本文提出了基于遥感技术、地理信息技术和全球定位系统进行"两违"动态监测的新方法.基于国产高景卫星数据进行一月一周期的监测,发现并提取可疑图斑;结合行政区划、土地利用等数据进行图斑筛选;开发"两违"执法监测系统进行建库归档并提供精准的定位信息,辅助执法队员开展外业核查和执法工作.在多个市、县开展了应用,能够快速、动态发现"两违"线索,辅助外业执法,为城市管理提供可行、有效的技术手段.  相似文献   

城市环境下智能手机GNSS/视觉组合导航算法和性能评估     

李晗羽  刘通  许国昌  吕志平 《测绘科学技术学报》2021,38(5):470-476

通过将卫星定位和计算机视觉定位组合,可以使智能手机在城市、峡谷等卫星定位结果跳变或中断的情况下,仍为用户提供连续、高精度的位置服务.因此,为改善手机端卫星信号不理想区域的定位精度,设计和实现了GNSS与单目相机组合导航的实验.通过数据平滑、旋转矩阵求解等过程完成系统间的轨迹转换,并分析了坐标转换误差.使用结合贝叶斯估计的卡尔曼滤波对两种轨迹进行融合处理.最终结果表明,在城市环境下,GNSS与单目相机组合后,定位误差小于3 m的概率由21.21％提升至48.15％,小于5 m的概率由48.82％提升至70.03％.  相似文献   

Variations of Sr–Nd–Hf isotopic systematics in basalt during intensive weathering     

Jinlong Ma  Gangjian Wei  Yigang Xu  Wenguo Long 《Chemical Geology》2010,269(3-4):376-385

The Sr–Nd–Hf isotopic compositions of both saprolites and parent rocks of a profile of intensively weathered Neogene basalt in Hainan, South China are reported in this paper to investigate changes of isotopic systematics with high masses. The results indicate that all these isotopic systematics show significant changes in saprolites compared to those in corresponding parent rocks. The ⁸⁷Sr/⁸⁶Sr system was more seriously affected by weathering processes than other isotope systems, with ε_Sr drifts 30 to 70 away from those of the parent rocks. In the upper profile (> 2.2 m), the Sr isotopes of the saprolites show an upward increasing trend with ε_Sr changing from ~ 50 at 2.2 m to ~ 70 at 0.5 m, accompanying a upward increasing of Sr concentrations, from ~ 10 μg/g to ~ 25 μg/g. As nearly all the Sr of the parent rock has been removed during intensive weathering in this profile, the upward increasing of Sr concentrations in the upper profile suggests import of extraneous Sr. Rainwater in this region, which enriches in Sr (up to 139 μg/L) from seawater, may be the important extraneous source. Thus, the Sr isotopes of the saprolites in the upper profile may be mainly influenced by import of extraneous materials, and the Sr isotopic characteristics may not be retained. In contrast, the ε_Nd and ε_Hf of the saprolites drift only 0–2.6 and 0–3.7 away from the parent rocks, respectively. The negative drifts of the ε_Nd and ε_Hf are coupled with Nd and Hf losses in the saprolites; i.e., larger proportions of Nd and Hf loss correspond to lower ε_Nd and ε_Hf. Compared with the relative high Nd and Hf concentrations of the saprolites, the contributions of extraneous Nd and Hf both from wet and dry deposits of aeolian input are negligible. Thus, the ε_Nd and ε_Hf changes in the profile are mainly resulted from consecutive removal of the Nd and Hf. Calculation indicates that the ¹⁴³Nd/¹⁴⁴Nd and ¹⁷⁶Hf/¹⁷⁷Hf ratios in saprolites are all significantly lower than their initial values in the parent rock. Simply removing part of the Nd and Hf by incongruent decomposing some of the minerals may not account for this. Fractionation should be happen, which ¹⁴³Nd and ¹⁷⁶Hf may be preferentially removed from the profile relative to ¹⁴⁴Nd and ¹⁷⁷Hf during intensive chemical weathering, resulting in lower ¹⁴³Nd/¹⁴⁴Nd and ¹⁷⁶Hf/¹⁷⁷Hf ratios in saprolites relative to the parent rock, even though details for this process is not known. A positive correlation is observed between the ε_Nd and ε_Hf of the saprolites. Interestingly, the saprolites with a net loss of Nd and Hf in the upper profile show good positive correlation, and the regression line parallels the terrestrial array. By contrast, saprolites with a net gain of Nd and Hf in the lower profile generally show higher ε_Hf values at a given ε_Nd value, and the regression line between these ε_Nd and ε_Hf appears to parallel the seawater array. This supports the hypothesis that the contribution of continental Hf from chemical weathering release is the key to the obliquity of the seawater array away from the terrestrial array of the global ε_Nd and ε_Hf correlation. Our results also indicate that caution is needed when using ε_Sr, ε_Nd, and ε_Hf to trace provenances for sediments and soils.  相似文献   

天津建设北方国际航运中心政策评价——基于PMC指数模型          下载免费PDF全文

华欣  吕成双 《海洋开发与管理》2022,39(3):94-100

文章以北方国际航运中心相关政策为研究对象,从其作用机理出发,通过Python脚本实现高频词提取,构建了适用于北方国际航运中心政策的PMC评价指标体系,对其中6项具有代表性的专项政策进行实证分析。结果表明,天津市委出台的政策的PMC指数略高于国务院出台政策;政策作用对象与政策内容间存在正相关性;虽然目前北方国际航运中心政策均处于良好级别且随时间推移得分呈现上升趋势,但仍存在港城联动性不足、保障措施不足、政策作用的具体对象不完善等问题。基于以上问题,提出增强港城联动性、优化政策保障措施、细化政策应用对象等相应的政策建议,以期进一步完善国际航运中心政策内容。  相似文献   

基于多尺度有限元的海上升压站脚靴式桩套筒连接结构分析研究     

张伟  张坤  姜贞强  孙震洲  王永发  吕国儿  陈杰峰 《海洋工程》2022,40(2):55-66

脚靴式海上升压站导管架的桩套筒与主导管的连接结构是关键荷载传递部位。整体梁系有限元模型无法反应局部板型结构的失效状态;截断板系有限元模型则受制于边界条件的合理性,结果不够精确。文中基于某工程海上升压站,建立不同精细化范围的多尺度有限元模型及不同边界条件的截断模型,对结构屈服失效及屈曲失效复核的同时论证了局部网格对计算精细程度的影响及截断模型对边界条件的敏感性;此外,研究了轭板板厚及应力比对屈曲失效的敏感程度,为今后海上升压站脚靴结构不同阶段的设计、优化提供参考和借鉴。  相似文献   

基于INS/DVL/GPS的UUV组合导航技术分析          下载免费PDF全文

吕志刚 《数字海洋与水下攻防》2022,5(6):546-552

水下组合导航是 UUV 完成长航时水下自主航行和任务的技术保障和基础,而基于 INS/DVL/GPS 的组合导航是当前 UUV 的主流组合导航方式,可解决导航误差随时间积累的难题,满足 UUV 长航时水下航行的要求。介绍了水下组合导航系统的结构和组成以及关键技术,并详细论述了初始对准算法、纯惯性解算算法、组合导航算法、DVL 标定算法和校准算法。  相似文献   

不同雨强对杉木和米槠林地表径流和可溶性有机碳的影响     

付林池  谢锦升  胥超  吕茂奎  陈坦  刘小飞  杨玉盛 《亚热带资源与环境学报》2014,(4):9-14

采用径流小区法,对中亚热带地区的杉木人工林和米槠次生林在不同雨强下径流量和可溶性有机碳（DOC）流失浓度进行比较研究。结果表明：在小雨、中雨、大雨和暴雨4场降雨过程中,米槠次生林和杉木人工林的地表径流量和DOC流失浓度变化趋势一致,即降雨强度增加,地表径流量也随之增加。DOC浓度均呈现了随着雨强的增加而逐渐降低的趋势。说明降雨强度对径流量和DOC浓度均产生了较为明显的影响;米槠次生林和杉木人工林的地表径流量之间差异不显著,米槠次生林和杉木人工林的DOC流失浓度除大雨外均达到显著性水平差异（P〈0.05）,说明植被类型对地表径流量影响较小,对DOC浓度具有较明显的影响。  相似文献   

基于ROMS模式利用集合最优插值同化沿轨海表面高度异常数据的研究   总被引：2，自引：1，他引：1  

LYU Guokun  WANG Hui  ZHU Jiang  WANG Dakui  XIE Jiping  LIU Guimei 《海洋学报(英文版)》2014,33(7):72-82

The ensemble optimal interpolation （EnOI） is applied to the regional ocean modeling system （ROMS） with the ability to assimilate the along-track sea level anomaly （TSLA）. This system is tested with an eddy-resolving system of the South China Sea （SCS）. Background errors are derived from a running seasonal ensemble to account for the seasonal variability within the SCS. A fifth-order localization function with a 250 km localization radius is chosen to reduce the negative effects of sampling errors. The data assimilation system is tested from January 2004 to December 2006. The results show that the root mean square deviation （RMSD） of the sea level anomaly decreased from 10.57 to 6.70 cm, which represents a 36.6% reduction of error. The data assimilation reduces error for temperature within the upper 800 m and for salinity within the upper 200 m, although error degrades slightly at deeper depths. Surface currents are in better agreement with trajectories of surface drifters after data assimilation. The variance of sea level improves significantly in terms of both the amplitude and position of the strong and weak variance regions after assimilating TSLA. Results with AGE error （AGE） perform better than no AGE error （NoAGE） when considering the improvements of the temperature and the salinity. Furthermore, reasons for the extremely strong variability in the northern SCS in high resolution models are investigated. The results demonstrate that the strong variability of sea level in the high resolution model is caused by an extremely strong Kuroshio intrusion. Therefore, it is demonstrated that it is necessary to assimilate the TSLA in order to better simulate the SCS with high resolution models.  相似文献   

玲珑金矿大开头矿区Bi特征及指示意义     

胡宝群  高海东  申玉科  郭涛  吕古贤  武际春 《物探与化探》2014,(6)

在金矿床中,金、铋常常相伴产出,在金矿体周围存在明显的铋异常,它可作为重要的指示元素。笔者研究了玲珑金矿不同岩石中铋与金含量之间的关系,比较了基岩地球化学剖面中两元素的相关性,采用电子探针分析了主要矿石矿物中铋和金的含量,发现不同类型岩石中铋含量差异明显,铋在矿体中含量远高于围岩,在矿区中铋与金呈幂函数正相关,铋原生晕规模大、衬度高,与金都是以独立矿物相形式存在。在玲珑金矿化探找矿中,铋含量高,与金呈较好的正相关关系,是最佳指示元素之一。  相似文献