基于扩展关系模型的整体空间数据管理

空间数据模型和数据管理是地理信息系统 (GIS)最重要的研究领域之一。该文介绍一体化的数据模型———扩展关系模型和以此为基础的 ,由作者设计的GIS软件原型系统———GEODBMS。GEODBMS使用统一的数据库管理系统 (DBMS)同时管理图形和属性数据 ;使用改进的四叉树———交叠四叉树索引空间目标 ;使用扩展的SQL语言进行空间查询 ;使用数据恢复和并发控制方法来加强分布式环境下数据的安全性和一致性维护     

基于Remez迭代算法求解差分系数的双相介质自适应有限差分正演模拟

利用传统有限差分方法对基于Biot理论的双相介质波动方程进行数值求解时,由于慢纵波的存在,数值频散效应较为明显,影响模拟精度.相对于声学近似方程及普通弹性波方程,Biot双相介质波动方程在同等数值求解算法和精度要求条件下,其地震波场正演模拟需要更多的计算时间.本文针对Biot一阶速度-应力方程组发展了一种变阶数优化有限差分数值模拟方法,旨在同时提高其正演模拟的精度和效率.首先结合交错网格差分格式推导Biot方程的数值频散关系式.然后基于Remez迭代算法求取一阶空间偏导数的优化差分系数,并用于Biot方程的交错网格有限差分数值模拟.在此基础上把三类波的平均频散误差参数限制在给定的频散误差阈值和频率范围内,此时优化有限差分算子的长度就能自适应非均匀双相介质模型中的不同速度区间.数值频散曲线分析表明:基于Remez迭代算法的优化有限差分方法相较传统泰勒级数展开方法在大波数范围对频散误差的压制效果更明显;可变阶数的优化有限差分方法能取得与固定阶数优化有限差分方法相近的模拟精度.在均匀介质和河道模型的数值模拟实验中将本文变阶数优化有限差分算法与传统泰勒展开算法、最小二乘优化算法进行比较,进一步证明其在复杂地下介质中的有效性和适用性.     

石家庄地震前兆台网月评价系统

基于VB语言,利用C/S架构,编写石家庄地震前兆台网月评价系统,设置不同功能单元,开展仪器运行监控、台网日常运维监控,通过界面选择相应日期,读取省前兆台网中心发布的《运行监控日报》等Excel文件,使用input box函数等在文本框中输入、统计、计算,并显示地震前兆台网月评价成绩及台网运行情况。     

1992-2014年河北省流动重力资料整理

系统整理河北省1992-2014年流动重力资料,利用LGADJ数据处理软件,对每期重力数据进行单期平差、多期整体平差计算,改正历史遗留问题,利用差分结果绘制145幅流动重力等值线差分图,通过具体异常点位及重力变化分析,得出：①地震前重力场变化强度与震级大小存在相关性;②流动重力观测资料地震前具有较为明显的前兆异常反应;③地震均发生在重力变化的“0”等值线附近地区。     

基于移动平台的测震应急流动台现场监控系统的设计与实现

流动测震观测是在大地震发生以后开展的一项重要的地震应急响应工作,能够获得震区高质量的地震数据,而野外环境的复杂性对测震应急流动台的架设提出了较高的要求。本文通过对地震应急流动现场工作进行需求分析,设计并实现了一种基于IOS系统的测震应急流动台现场监控系统,能够让现场工作队员快速获取流动台数据和状态信息,有利于流动台的快速架设,提高了应急流动观测现场工作的效能。     

城市地震应急避难场所展示系统的设计与实现

针对城市应急避难场所信息化建设过程中存在的问题,以天津市地震应急避难场所的实际情况为数据基础,开发了基于Google地图API技术的城市地震应急避难场所展示系统。该系统实现了应急避难场所信息查询、地图量测、避难场所最优路径和应急避险科普宣传等公共服务功能。系统的设计与实现不仅有利于城市居民及时方便准确地获取居住地周围地震应急避难场所空间分布信息和应急避险等知识,同时在城市突发灾害后的抢险救灾、疏散及安置居民等方面起到重要作用。     

Application of a wide-field electromagnetic method to shale gas exploration in South China

In an effort to reduce the shale gas exploration risks and costs, we applied the wide-field electromagnetic method (WFEM), because of its strong anti-interference capability, high resolution, ability to conduct exploration at large depths, and high efficiency, to the Bayan Syncline in the South Huayuan block, Hunan Province. We collected rock samples and analyzed their resistivity and induced polarization (IP) and built A series of two-dimensional models for geological conditions to investigate the applicability of WFEM to different geological structures. We also analyzed the correlation between TOC of shale and the resistivity and IP ratio to determine the threshold for identifying target formations. We used WFEM to identify the underground structures and determine the distribution, depth, and thickness of the target strata. Resistivity, IP, and total organic carbon were used to evaluate the shale gas prospects and select favorable areas (sweet spots) for exploration and development. Subsequently, drilling in these areas proved the applicability of WFEM in shale gas exploration.     

Snowdrift effect on snow deposition: Insights from a comparison of a snow pit profile and meteorological observations in east Antarctica

A high-frequency and precise ultrasonic sounder was used to monitor precipitated/deposited and drift snow events over a 3-year period(17 January 2005 to 4 January 2008) at the Eagle automatic weather station site,inland Antarctica.Ion species and oxygen isotope ratios were also generated from a snow pit below the sensor.These accumulation and snowdrift events were used to examine the synchronism with seasonal variations of δ~(18)O and ion species,providing an opportunity to assess the snowdrift effect in typical Antarctic inland conditions.There were up to 1-year differences for this 3-year-long snow pit between the traditional dating method and ultrasonic records.This difference implies that in areas with low accumulation or high wind,the snowdrift effect can induce abnormal disturbances on snow deposition.The snowdrift effect should be seriously taken into account for high-resolution dating of ice cores and estimation of surface mass balance,especially when the morphology of most Antarctic inland areas is similar to that of the Eagle site.     

面向目标自适应有限元法的带地形三维大地电磁各向异性正演模拟

传统三维大地电磁各向异性模拟均是基于规则六面体网格,计算精度有限且较难拟合复杂地质条件.本文采用面向目标自适应非结构矢量有限元法,对三维大地电磁各向异性介质进行模拟.首先从电场双旋度方程出发,利用伽辽金方法建立变分方程;然后利用电流密度连续性条件构建适合大地电磁各向异性问题的加权后验误差估计方法,实现面向目标的网格自适应正演;最后通过典型算例分析各向异性对网格自适应和大地电磁响应的影响特征以及各向异性的识别方法.本文算法能够高精度地拟合起伏地表和任意各向异性介质,适用于分析复杂地电条件大地电磁响应特征,为提高大地电磁资料解释水平提供了理论基础.     

APPLICATION OF UAVLS TO RAPID GEOLOGICAL SURVEYS

Three-dimensional scanning with LiDAR has been widely used in geological surveys. The LiDAR with high accuracy is promoting geoscience quantification. And it will be much more convenient, efficient and useful when combining it with the Unmanned Aerial Vehicle (UAV). This study focuses on UAV-based Laser Scanning (UAVLS)geological field mapping, taking two examples to present advantages of the UAVLS in contrast with other mapping methods. For its usage in active fault mapping, we scanned the Nanpo village site on the Zhangxian segment of the West Qinling north-edge fault. It effectively removed the effects of buildings and vegetation, and uncovered the fault trace. We measured vertical offset of 1.3m on the terrace T₁ at the Zhang river. Moreover, we also scanned landslide features at the geological hazard observatory of Lanzhou University in the loess area. The scanning data can help understand how micro-topography affects activation of loess landslides. The UAVLS is time saving in the field, only spending about half an hour to scan each site. The amount of average points per meter is about 600, which can offer topography data with resolution of centimeter. The results of this study show that the UAVLS is expected to become a common, efficient and economic mapping tool.