水平气压梯度力差分格式误差的定量分析

通过分析发现地形坐标系中气压梯度力差分格式的计算误差应分为二类，其中，第二类误差在水平坐标面倾斜时出现。这种误差可理解为将水平坐标面上的气压(或位势高度)插回到等高面(或等压面)上的插值误差。 构造气压梯度力差分格式的目的正是为了减小这种第二类误差，而不是其他误差。 误差分析表明静力扣除法和Corby 格式的第二类误差都很小，比一般方法的误差小约一个量级。分析还表明第二类误差产生的主要原因是由于气压随高度非线性变化。依据这一分析思路，本文改进了#As(z)#a坐标系中的静力扣除法。 改进后的方法比改进前的误差小约一个量级。     

航磁ΔT平面归一化总梯度方法及其在内蒙陆西凹陷的应用

本文首次提出将剖面归一化总梯度方法推广到平面加以应用,得到平面归一化总梯度方法,并根据剖面归一化总梯度的计算公式相应地推导了平面归一化总梯度的计算公式,将其应用到内蒙陆西凹陷探测油气田,取得了一定的地质效果。     

Interannual variability of the convective activities associated with the east asian summer monsoon obtained from tbb variability

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应用地形信息精化山区大地水准面

在介绍由高程异常确定大地水准面有关理论的同时,提出了用地形质量计算重力异常垂直梯度的方法,结合高程异常资料,可以使山区大地水准面得到精化。将本方法应用于珠穆朗玛峰,获得其大地水准面高为－ ３０．３６ ｍ 。     

佛坪自然保护区植物群落物种多样性与海拔梯度的关系

用多元统计分析方法研究了佛坪自然保护区植物群落多种性及群落各生长型多样性特征沿海拔梯度的变化。结果表明：1）植物群落的Shannon指数与Simpson指数及物种丰富度与海拔梯度均呈显著负相关关系;2）乔木层的物种多样性沿海拔梯度的变化则体现了“中国高度膨胀”的规律,即中等海拔高度上多样性高而低海拔和高海拔多样性较低;3）灌木层丰富度指数在1600-1700m之间有个很不明显的峰值,而其它4个指标沿海拔呈单调的下降趋势;4）草本层植物多样性呈先降后升的趋势,在中等海拔高度较低。     

工程滑坡滑带土抗剪强度与地形坡度的关系

对 12个滑坡滑带土的抗剪强度和相应地形坡角进行了回归分析 ,发现滑带土的抗剪强度与地形坡角之间呈直线关系。     

A field study of the coupled effects of aquifer stratification,fluid density,and groundwater fluctuations on dispersivity assessments

A number of experimental studies have tackled the issue of solute transport parameter assessments either in the laboratory or in the field. But yet, the behavior of a plume in the field under density driven forces, is not well known due to possible development of instabilities. Some field tracer tests on the fate of plumes denser than native groundwater such as those encountered under waste disposal facilities, have pointed out the processes of sinking and splitting at the early stage of migration. The process of dispersion was widely investigated, but the range of dispersivity values obtained from either experimental tests, or numerical and theoretical calculations is still very large, even for the same type of aquifers. These discrepancies were considered to be essentially caused by soil heterogeneities and scale effects. In the meantime, studies on the influence of sinking and fingering have remained more scarce. The objective of the work is to analyze how transport parameters such as dispersivities can be affected by unstable conditions, which lead to plume sinking and fingering. A series of tracer tests were carried out to study under natural conditions, the transport of a dense chloride solution injected in a shallow two-layered aquifer. Two types of experiments were performed: in the first type, source injection was such that the plume could travel downward from one layer to the other of higher pore velocity, and in the second one, the migration took place only in the faster layer. The results suggest some new insights in the processes occurring at the early stages of a dense plume migration moving in a stratified aquifer under groundwater fluctuations, which can be summarized through the following points: (i) Above a stability criterion threshold, a fingering process and a multi modal plume transport take place, but local dispersivities can be cautiously derived, using breakthrough curves matching. (ii) When water table is subject to some cycling or rising, the plume can be significantly distorted in the transverse direction, leading to unusual values of the ratio between longitudinal and transverse dispersivities. (iii) Under stable conditions, for example in the case of straightforward injection in the faster aquifer layer, longitudinal dispersivity is greater than the transverse component as usually encountered, and the obtained transport parameters are closed to macro dispersivity values, which reach their asymptotic limit at very short distances. (iv) The classical scale effect about the varying dispersivity at short distances could be a process mainly due to the distance required for a plume stabilization.     

井地直流电法三维数值模拟中若干问题研究

讨论了地下垂直线源分段计算和场叠加的方法,并实现了在套管上供直流电的三维数值模拟。讨论了大型容量矩阵的压缩存储方式,采用数组和结构体相结合的方法实现容量矩阵的一维链表式压缩存储。在求解超大型稀疏线形方程组时引入不完全Cholesky分解稳定化的双共轭梯度算法(ICBG),通过与均匀半空间垂直线源解析解的对比,证明了该算法是准确可靠的。     

引力向量及梯度张量在坐标系之间的变换

引力向量和引力梯度张量在局部和全局坐标系间的转换过程是对卫星重力梯度测量进行模拟研究的主要手段和重要步骤.提出了利用计算机符号运算辅助推导该转换过程的新思想.首先通过对该过程进行分析,指出其运算繁琐复杂;然后通过对理论推导过程的分解,确定了引力向量和引力梯度张量在局部和全局坐标系之间转换的各关键步骤;并借助于计算机符号运算实现了这一转换过程的计算机推演,成功地得到了完整的符号公式结果.所编写的符号推演程序在多台计算机的多种平台上获得了一致的结果.实验结果表明,计算机符号运算对于公式体系繁杂的卫星重力学理论研究来说具有极大的增效作用.     

夏季青藏高原TBB低频振荡及其与华中地区旱涝的关系

利用17年(1980—1994年和1997—1998年)逐候GMS TBB资料,对华中地区夏季旱涝年的TBB候距平场进行了合成分析,研究了夏季青藏高原TBB的低频(10~20天和30~60天)振荡及其同华中地区旱涝的关系。结果表明,青藏高原东南部(27°~30°N,90°~100°E)是低频振荡最为活跃的地区,青藏高原东南部和华中地区TBB存在正相关关系,其相关程度涝年比旱年更为显著。对华中地区旱涝而言,青藏高原东南部的30~60天振荡比10~20天振荡敏感性要强。华中地区涝(旱)年,青藏高原东南部存在较强(弱)的低频(30~60天)TBB负值中心,其影响方式有的自西向东传播,有的同华中地区低频(30~60天)TBB同时加强或减弱。青藏高原低频(30~60天)TBB的负值位相有利于对流云团的生成和发展。