Joint three-dimensional inversion of coupled groundwater flow and heat transfer based on automatic differentiation: sensitivity calculation, verification, and synthetic examples

Inverse methods are useful tools not only for deriving estimates of unknown parameters of the subsurface, but also for appraisal of the thus obtained models. While not being neither the most general nor the most efficient methods, Bayesian inversion based on the calculation of the Jacobian of a given forward model can be used to evaluate many quantities useful in this process. The calculation of the Jacobian, however, is computationally expensive and, if done by divided differences, prone to truncation error. Here, automatic differentiation can be used to produce derivative code by source transformation of an existing forward model. We describe this process for a coupled fluid flow and heat transport finite difference code, which is used in a Bayesian inverse scheme to estimate thermal and hydraulic properties and boundary conditions form measured hydraulic potentials and temperatures. The resulting derivative code was validated by comparison to simple analytical solutions and divided differences. Synthetic examples from different flow regimes demonstrate the use of the inverse scheme, and its behaviour in different configurations.     

初至波地震层析技术及其在四川复杂地区的应用

近地表速度场的重建是获得准确静校正量的关键。根据实际地震数据的初至波时间建立初始速度模型;采用改进的最短路径射线追踪算法进行正演;利用改进的约束带阻尼联合迭代重建技术(CDSIRT)求解大型、稀疏的方程组来反演近地表的速度场。理论模型和实际资料的反演结果表明,该方法能稳定、快速、准确地重建复杂地区的近地表速度场,建立准确的近地表速度场,从而可计算准确的静校正量,保证复杂地区的构造成像。     

网络环境下地图自动综合框架模型研究

计算机技术的普及、网络通信技术的迅速发展,不但使地图学发生了深刻的变革,也给制图综合带来了新的机遇和挑战。在分析了网络环境下地图自动综合的现有研究方法及其优缺点的基础上,针对互联网这一特定的信息交换平台,提出了网络环境下地图自动综合的总体设计框架,建立了以实例数据库为核心的用户需求提取模型。同时也讨论了面向无级比例尺的矢量数据的信息压缩。     

云状排序记录的计算机自动审核方法

加强对地面资料计算机自动审核技术的研究,对于实现地面气象观测资料的计算机自动审核、提高地面观测资料的审核质量和工作效率具有重要意义。云状记录的排序分析技术,是地面气象观测资料计算机自动审核中的一个关键性技术难点。文章介绍一种分类分析方法,即根据总云量、低云量和云状的不同配合情况分为几种记录类型,对每一种类型再根据几种不同情况进行分析,在分析判断过程中,将29种云状符号射影到双字(32位)变量中,使分析判断程序简单明了。在浙江省地面气象资料计算机自动审核软件中进行试用,结果表明该方法对提高云观测资料的审核质量具有明显效果。     

Ray-centred coordinate systems in anisotropic media

Whereas the ray-centred coordinates for isotropic media by Popov and Pšenčík are uniquely defined by the selection of the basis vectors at one point along the ray, there is considerable freedom in selecting the ray-centred coordinates for anisotropic media. We describe the properties common to all ray-centred coordinate systems for anisotropic media and general conditions, which may be imposed on the basis vectors. We then discuss six different particular choices of ray-centred coordinates in an anisotropic medium. This overview may be useful in choosing the ray-centred coordinates best suited for a particular application. The equations are derived for a general homogeneous Hamiltonian of an arbitrary degree and are thus applicable both to the anisotropic-ray-theory rays and anisotropic common S-wave rays.     

地震仪自动换档设计

鉴于测震中电子放大地震仪放大器的输出动态范围窄的缺陷，笔者作了自动换档衰减放大倍数的电路技术设计。本设计在长周期、短周期、宽频带等各种电子放大地震仪上适当改制或重新设计放大板即可应用，从而可几十倍甚至更大地拓宽电子放大地震仪的输出动态范围，大幅度增强其适用性。     

A neural-tree-based system for automatic location of earthquakes in Northeastern Italy

A neural network system for P and S-picking and location of earthquakes in Northeastern Italy is described. It is applied to 7108 seismograms corresponding to 1147 earthquakes occurring in Northeastern Italy and surrounding area in the period 2000–2003. Its results are compared with two sets of manual picks and with the picks performed by the existing seismic alert system. The new system recognizes 89% and 67% of P and S arrival times, respectively, which allows locating 92% of the earthquakes. P and S-picks differ from the best available manual picks by 0.00 ± 0.07 s and 0.00 ± 0.18 s, respectively. The corresponding earthquake locations differ by −0.18± 0.77 km in longitude, 0.10± 0.62 km in latitude and 0.1± 2.0 km in depth. These results suggest its use for alert purposes and rapid production of preliminary bulletins.Considering a subset of picks that are common to all the available data sets, the absolute accuracy (i.e., the inverse of the standard deviation of differences between the estimated and the true, unknown arrival times) of each picking method is estimated. The best available manual data set has standard deviation 0.03 s for P waves and 0.07 s for S waves, while for the new system it is 0.06 s and 0.18 s for P and S waves, respectively.This paper has not been submitted elsewhere in identical or similar form, nor will it be during the first three months after its submission to Journal of Seismology.     

自编测井绘图程序在地质报告中的应用

以平面图形图象设计软件CorelDRAW12为平台,用CorelDRAW12 VBA语言,对CorelDRAW12进行二次开发,将煤田测井常用的"CLGIS煤田测井综合解释程序"处理生成的、不能被其它程序调用的*.DAT数据库文件,转换成可供其它程序方便调用的文本文件格式,再绘制成地质报告中测井部分的各种平面图形.该程序绘制的平面图形文件,可方便地转换成AutoCAD、*.GIF、*.JPG、*.BMP等十多种格式的图形文件.兼容性强,图形美观,编辑容易、方便、简单,打印出图快.CorelDRAW12的坐标可根据绘图需要,反复随意确定,使得程序编写简单.该方法简单易学,实用性强,有一定的推广和实用价值.