时间谱电阻率法的一维快速正演算法研究

基于偶极－偶极电极装置的瞬变响应表达式,建立了双极源电场的等效偶极和三次插值的快速近似看法。通过在一些典型地电新面上对算法的试算,表明三次插值法是一种较稳定的快速算法,从而实现了时间谱电阻率法一维正演的快速计算。     

论过去资料在数值天气预报中使用的理论和方法

对中国气象学家在数值天气预报中使用过去实况演变资料的理论和方法作卫概要性总结,其中不仅讨论了近期实况演变资料的应用,还了积累数十年的历史资料的应用问题。文中强调要改变对数值预报问题的提法,回顾了由初值问题改为演变问题,再改为反问题的历史。     

频率域航空电磁法一维正演与探测深度

计算了偶极一偶极方式均匀半空间的频率域航空电磁响应及层状模型的相对异常响应,阐明了大地电导率、磁化系数,以及飞机飞行高度、探测装置、收发距对电磁响应的影响,计算结果说明了频率域航空电磁法的探测能力和探测条件．分析了三层模型的相对异常响应,给出了基于层状模型确定探测深度的方法．在水平共面方式下,收发距8m,飞行高度30m时,在3～4ppm噪声水平条件下,100Ωm大地探测深度为120m．     

基于频率域高阶有限差分法的正演模拟及并行算法

在弹性波频率空间域有限差分数值模拟方面,差分网格及边界条件是影响弹性波模拟成功与否的关键,为了压制数值模拟中的网格频散,采用25点有限差分算子,建立了有限差分矩阵方程,且借鉴匹配层衰减边界条件思想,设计了弹性波频率空间域有限差分数值模拟算法。由于采用高阶有限差分法来提高差分格式的精度,将会导致计算量显著增加,为此,对频率空间域有限差分弹性波数值模拟方法,采用流水线技术与分治策略进行了并行算法研究,提高了计算效率,使得在合理的计算时间内更精确地模拟弹性波在弹性介质中的传播过程。     

用模式匹配算法研究层状各向异性倾斜地层中多分量感应测井响应

利用数值模式匹配技术,研究并建立层状各向异性倾斜地层中多分量感应测井响应的快速数值模拟算法.首先将位于井轴上的三个相互正交磁偶极子转化成关于极角θ的三个谐变分量的叠加,以便将三个正交磁偶极子电磁场的正演问题完全简化成三个谐变分量电磁场的轴对称定解问题,并给出电磁场各个谐变分量在井轴上满足的边界条件,保证电磁场在井轴附近仍然可解.然后利用数值模式匹配技术建立电磁场各个谐变分量的正演过程,得到层状各向异性地层中磁流源并矢Green函数的半解析表达式,给出计算层状各向异性倾斜地层中多分量感应测井响应的具体方法,最后通过数值计算结果证明该算法的有效性并考察几种不同情况下多分量感应测井响应特征.     

莱芜市耕地保护面临的问题及对策研究

目前,莱芜市面临的耕地保护问题主要是:耕地总量日益减少,人地矛盾日趋尖锐;耕地总体质量不高,且退化日趋严重;耕地后备资源不足,土地开发整理潜力有限;城镇化进程加快,各类建设对耕地需求加大。对此,笔者进行了深入调研,并提出了可行性建议。     

Analysis of the Water Factor with the Major Environmental Issues in the Sanjiang Plain

Water has an irreplaceable role and function in determining the main factors of the environmental, ecological and geological environment. It is one of the most important factors impacting ecological balance, ecological and geological environment and other factors or components. When the water availability changes, other factors or components can follow chains of reaction, changing or rebalancing accordingly. The water factor of the Sanjiang plain is discussed, characterized and analyzed in detail. We illustrate that water availability can have a large impact on environmental and geological problems.     

地质力学领域近年来发展状况及相关问题与对策分析

通过系统收集整理和分析2006年以来中国地质科学院地质力学研究所在人才队伍建设、机构设置与学科布局、科研经费投入等方面的相关资料,提出了目前在发展地质力学过程中,人才队伍、学科布局与发展以及经费投入等方面存在的问题,并进行了对策分析,以期为地质力学战略研究提供重要基础支撑,为中长期发展规划提供决策依据,从而早日实现地质力学的跨越式发展,并为国家经济社会发展提供更好的服务。      

EXPLICIT SOLUTIONS FOR SEEPAGE INFILTRATING INTO A POROUS EARTH DAM DUE TO PRECIPITATION

Steady two-dimensional gravity-driven seepage in homogeneous porous lumps is studied with the help of conformal mappings and boundary value problem technique. The Terzaghi flow pattern for a trapezoidal dam exposed to a heavy rainstorm is analysed. For a semi-circular massif, the influence of impervious bed inclination is studied. Recharge–discharge distributions, hinge points, gradients along the lump contour as well as the total flow rate exhibiting water–bearing capacity of the unit are found in explicit form. Generalizations for non-isobaric boundary conditions are discussed.     

Stabilizing ill-conditioned linear complementarity problems

Least-squares adjustment with inequality constraints is equivalent to solving a linear complementarity problem (LCP) with a positive definite matrix; the latter has, however, received little attention in geodesy. Two kinds of LCP solution methods (direct and approximation) have been analysed from the point of view of solution stability. It has been found that they can result in an unreliable solution to an unstable LCP with a positive definite matrix, the extent of which depends on the corresponding submatrix. Several proposals for improving the solutions to the unstable LCP are suggested. Two examples are given. Received: 5 June 1997 / Accepted: 28 January 1999