An automated approach for conditioning discrete fracture network modelling to in situ measurements

Creation of a geological fracture network model conditioned to in situ geometric measurements is of great importance to geoprofessionals, as fractures dominate pathways for fluid flow, a major concern for many engineering applications. This paper introduces and applies the Stochastic Nelder Mead simplex method to automatically calibrate stochastic parameters of geometric characterisations of a discrete fracture network model. This method can overcome the non-convergence of a previous exploratory approach on the classic Nelder Mead method by others, and is an effective substitution to the manual trial-and-error method and is complementary to existing conditional simulation approaches. The procedure to integrate the Stochastic Nelder Mead with a discrete fracture network is presented in detail, and a case study was conducted. Results show that the improved model can better handle the stochastic nature of the underlying system and effectively simulates the observed number and mean trace length of these fractures, although the model results underestimate its standard deviation. Simulated distributions of trace lengths and spacings are within acceptable ranges except for some small offsets, which can be adjusted during model runs.     

基于MapBasic的等高线赋值设计与实现

等高线是地形表达常用的形式之一,它是地理信息系统基础的数据模型,而高程则是构成等高线的重要属性。本设计利用MapBasic编程语言实现了对矢量化后的无值等高线批量赋予高程值[1],有效地提高了等高线高程录入的效率和准确度。文章首先介绍了自动赋值算法的基本思想,然后,结合MapBasic关键代码,从赋值等高线的获取与排序、等高线属性的修改与赋值等方面阐述了MapInfo中实现等高线自动赋值的思路,并最终给出实验结果。     

地震前兆观测仪器的校准与标定辨析

对地震行业常用的"标定"术语和计量领域的"校准"术语之间的异同进行分析,同时提出目前"标定"在保障地震仪器观测质量中的作用及限制,最终指出并强调了"校准"在确保地震仪器观测量值单位统一、量值准确的法定地位。     

河北测震台网脉冲标定管理系统设计与实现

河北测震台网脉冲标定管理系统软件具有脉冲标定量取、标定异常处理、基于数据库的脉冲标定管理、日志、用户管理等功能.该系统在Windows XP操作系统环境下,采用VC＋＋和Access数据库进行开发.在河北测震台网投入运行后,有效提高值班人员的工作效率和质量,具有良好的推广应用前景.     

一种基于比长基线场天文大地测量的陀螺经纬仪校准装置

提出以场地条件类似的比长基线场代替天文大地点进行陀螺经纬仪的校准。从观测原理的误差分析入手,分析对测量精度的要求和仪器选取;将GPS和工业电子经纬仪用于天文大地测量,并对观测方法加以改进,建立一套基于比长基线场的陀螺经纬仪方位角校准装置;最后,给出校准装置的不确定度分析。实验证明,其精度能达到规程的要求。     

水文数字高程模型在珠江流域入海径流模拟中的应用

为了计算珠江流域入海径流的线源,引入水文数字高程模型(H-DEM).利用观测的降水和流域流量订正模型参数,改造后的模型模拟结果与站点资料对比,能够基本再现季节变化和年变化,这表明改造后的H-DEM可以应用于亚热带地区.采用改造后的模型对珠江流域入海径流进行模拟研究,结果显示线源和点源都有明显的线性趋势变化和年代际变化特征.     

多波束测深系统内部参数的设定与校准

以EM710RD多波束测深系统为例,通过高精度测量获得的系统参数,对该系统内部参数的设定与校准过程进行详细分析,从而为多波束测量外业工作提供参考依据。     

基于三角网构建海底DEM的抽稀算法

为压缩海量水深数据,实现在高分辨率下快速、完整和准确地表示海底地形,提出了一种基于三角网拓扑结构的数据抽稀方法。该方法利用Delaunay三角网的模型优势,快速寻找与水深点相关的区域。根据水深点对区域贡献度大小决定取舍。实验表明,该方法充分顾及海底地形变化趋势,能有效识别海底地形特征点,并且抽稀速度快、失真小、精度高。     

祁连山高山灌丛生物量及其分配特征

分布于青海云杉林上线的祁连山高山灌丛是祁连山水源涵养林效益最佳林型,研究高山灌丛生物量是生态系统生产力的重要体现,也是群落结构和功能的主要测度之一。以祁连山排露沟流域3 300～3 700 m高山灌丛为研究对象,采用标准地、样方收获法以及壕沟挖掘方法,对不同海拔高度10个固定样地灌丛生物量,器官生物量进行调查,分析了不同海拔梯度灌丛的叶、枝、须根、细根、粗根烘干重数据及其生物量分配特征。结果表明：祁连山高山灌丛总生物量为12 869.39±3 306.16 kg/hm²(平均值±标准差,n=10),其中器官分配以枝生物量所占比例最高,达32.21%,叶、须根、细根、粗根的比例分别为15.70%、14.06%、11.13%和26.90%。不同海拔梯度灌丛生物量器官分配比例差异较大,地上生物量平均为6 097.17kg/hm²,地下生物量平均为6 772.22kg/hm²,不同海拔根茎比在0.56～1.93之间变化,海拔3 500 m处根茎比达最大。祁连山高山灌丛生物量与海拔呈现显著的负相关（R² = 0.898 7,p＜0.01）,随着海拔的升高,灌丛总生物量,地上以及地下生物量均呈现下降的趋势。研究结果可为内陆河流域生态环境的保护及其高山灌丛对全球气候变化的响应研究提供重要理论依据和应用资料。     

Landform classification from a digital elevation model and satellite imagery

The Iranian Soil and Water Research Institute has been involved in mapping the soils of Iran and classifying landforms for the last 60 years. However, the accuracy of traditional landform maps is very low (about 55%). To date, aerial photographs and topographic maps have been used for landform classification studies. The principal objective of this research is to propose a quantitative approach for landform classification based on a 10-m resolution digital elevation model (DEM) and some use of an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image. In order to extract and identify the various landforms, slope, elevation range, and stream network pattern were used as basic identifying parameters. These are extractable from a DEM. Further, ASTER images were required to identify the general outline shape of a landform type and the presence or absence of gravel. This study encompassed a relatively large watershed of 451 183 ha with a total elevation difference of 2445 m and a variety of landforms from flat River Alluvial Plains to steep mountains. Classification accuracy ranged from 91.8 to 99.6% with an average of 96.7% based upon extensive ground-truthing. Since similar digital and ASTER image information is available for Iran, an accurate landform map can now be produced for the whole country. The main advantages of this approach are accuracy, lower demands on time and funds for field work and ready availability of required data for many regions of the world.