松辽盆地白垩系青山口组黑色页岩的形成环境及海水侵入的底流模式   总被引：6，自引：0，他引：6       下载免费PDF全文

王璞珺  王东坡  杜小弟 《沉积与特提斯地质》1996,16(1):34-43

通过对中央坳陷区两口钻井剖面和东南隆起区野外露头剖面的沉积学、矿物学和地球化学研究，认为松辽盆地白垩系青山口组黑色页岩形成于稳定分层的湖相环境；周期性海水注入形成的底流是导致水体分层和黑色页岩沉积的重要因素。  相似文献   

导线网可靠性分析和粗差探查     

黄加纳  吴俊昶 《武汉大学学报(信息科学版)》1997,(1)

采用相关平差算法计算导线网中每个观测值的多余观测分量和各类观测值的内可靠性指标，按统计假设检验理论构成观测值的粗差检测统计量，经过探查指出可能含有粗差的观测值。最后给出内可靠性分析的结果，并提出导线网设计和施测要点建议  相似文献   

利用共线方程对空间实验室影象进行数字几何纠正     

舒宁 《武汉大学学报(信息科学版)》1988,(3)

本文论述了利用共线方程对空间实验室影象实施数字几何纠正的理论依据、数据准备、外方位元素解求过程中参量的确定及锚点纠正法的可行性和纠正精度,提出了纠正过程中几个必须注意的环节,以提高精度,缩短机时。同时还介绍了自编软件包的组成。  相似文献   

平差参数的岭估计和压缩估计     

张方仁  汪晓庆 《武汉大学学报(信息科学版)》1989,(3)

当法方程的系数矩阵呈病态时,平差参数的统计性质就要变坏。为改善最小二乘估计,本文介绍岭估计和压缩估计,在一定条件下,岭估计和压缩估计的均方误差要小于最小二乘估计的均方误差。本文提出了各种求岭系数和压缩系数的方法,并对它们的使用提出了一些意见。  相似文献   

Statistical models for the estimation of net phosphorus sedimentation in lakes   总被引：2，自引：0，他引：2  

Yves T. Prairie 《Aquatic Sciences - Research Across Boundaries》1989,51(3):192-210

The empirical adequacy of four phosphorus mass-balance models is evaluated with respect to how the prediction error variance of the corresponding net sedimentation parameters is propagated in the steadystate equations. Using the criterion of minimum propagation error variance (PEV), different groups of lakes can be distinguished for which different empirical equations are used to predict net phosphorus sedimentation. The classification reduced prediction error significantly and also reflected different patterns of sedimentation. Application of this criterion to time-series of individual lakes shows that it is possible to determine a priori whether net annual sedimentation will be better correlated to the annual loading or to the lake content. The correlations depended also on the load/lake content ratio, suggesting that net sedimentation is best viewed as the sum of the partial sedimentation of the load and of the partial sedimentation of the lake content. On average, 25% of the load and 18% of the lake content are sedimented annually. Viewing net phosphorus sedimentation as a function of both the load and the lake content can also explain and predict the well-known cross-sectional correlation between phosphorus retention and water residence time.  相似文献   

配置法在导线平差中的应用     

周光文  余茂华 《华东地质学院学报》1989,12(3):81-87

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Validation and error analysis of a strata modelling technique     

A. D. Mayer  A. K. Isaac  P. Neve 《Geotechnical and Geological Engineering》1984,2(4):305-321

Summary Sources of error are investigated for a two-dimensional finite difference computer program designed to model strata deformation. The program calculates the displacements of a mesh of mass points, by the iterative solution of equations of equilibrium for the stresses acting on each mass point. The effect of errors on both displacement estimates and stress estimates is considered.Round-off errors are discussed analytically, while the effect of choosing too coarse a mesh density is demonstrated by comparison of two runs of the program with identical material properties, but different mesh densities. The influence of boundary conditions and the result of incomplete relaxation of the finite difference equations is estimated by comparison with Kirsch's analytical solution for a thin plate of finite width with a circular hole under unidimensional load.As a result of the analysis, estimators for stresses and displacements are derived, which make allowance for some of the sources of error; suitable boundary conditions for first and subsequent runs of the program are proposed; and a convergence criterion for the iterative process is suggested. These results are then applied to simulations of mining situations, together with various refinements of the basic model, such as separation and slip between adjacent strata, and an allowance for failure of material.  相似文献   

The structure of chaos in a potential without escapes     

G. Contopoulos  H. Papadaki  C. Polymilis 《Celestial Mechanics and Dynamical Astronomy》1994,60(2):249-271

We study the structure of chaos in a simple Hamiltonian system that does no have an escape energy. This system has 5 main periodic orbits that are represented on the surface of section by the points (1)O(0,0), (2)C ₁,C ₂(±y _c, 0), (3)B ₁,B ₂(O,±1) and (4) the boundary . The periodic orbits (1) and (4) have infinite transitions from stability (S) to instability (U) and vice-versa; the transition values of are given by simple approximate formulae. At every transitionS U a set of 4 asymptotic curves is formed atO. For larger the size and the oscillations of these curves grow until they destroy the closed invariant curves that surroundO, and they intersect the asymptotic curves of the orbitsC ₁,C ₂ at infinite heteroclinic points. At every transitionU S these asymptotic curves are duplicated and they start at two unstable invariant points bifurcating fromO. At the transition itself the asymptotic curves fromO are tangent to each other. The areas of the lobes fromO increase with ; these lobes increase even afterO becomes stable again. The asymptotic curves of the unstable periodic orbits follow certain rules. Whenever there are heteroclinic points the asymptotic curves of one unstable orbit approach the asymptotic curves of another unstable orbit in a definite way. Finally we study the tangencies and the spirals formed by the asymptotic curves of the orbitsB ₁,B ₂. We find indications that the number of spiral rotations tends to infinity as . Therefore new tangencies between the asymptotic curves appear for arbitrarily large . As a consequence there are infinite new families of stable periodic orbits that appear for arbitrarily large .  相似文献   

Estimating Variogram Uncertainty   总被引：10，自引：0，他引：10  

B. P. Marchant  R. M. Lark 《Mathematical Geology》2004,36(8):867-898

The variogram is central to any geostatistical survey, but the precision of a variogram estimated from sample data by the method of moments is unknown. It is important to be able to quantify variogram uncertainty to ensure that the variogram estimate is sufficiently accurate for kriging. In previous studies theoretical expressions have been derived to approximate uncertainty in both estimates of the experimental variogram and fitted variogram models. These expressions rely upon various statistical assumptions about the data and are largely untested. They express variogram uncertainty as functions of the sampling positions and the underlying variogram. Thus the expressions can be used to design efficient sampling schemes for estimating a particular variogram. Extensive simulation tests show that for a Gaussian variable with a known variogram, the expression for the uncertainty of the experimental variogram estimate is accurate. In practice however, the variogram of the variable is unknown and the fitted variogram model must be used instead. For sampling schemes of 100 points or more this has only a small effect on the accuracy of the uncertainty estimate. The theoretical expressions for the uncertainty of fitted variogram models generally overestimate the precision of fitted parameters. The uncertainty of the fitted parameters can be determined more accurately by simulating multiple experimental variograms and fitting variogram models to these. The tests emphasize the importance of distinguishing between the variogram of the field being surveyed and the variogram of the random process which generated the field. These variograms are not necessarily identical. Most studies of variogram uncertainty describe the uncertainty associated with the variogram of the random process. Generally however, it is the variogram of the field being surveyed which is of interest. For intensive sampling schemes, estimates of the field variogram are significantly more precise than estimates of the random process variogram. It is important, when designing efficient sampling schemes or fitting variogram models, that the appropriate expression for variogram uncertainty is applied.  相似文献   

雪峰山特长隧道平面控制测量基准的建立   总被引：2，自引：0，他引：2  

王守彬  李林  王新洲 《测绘信息与工程》2005,30(1):33-34

介绍了GPS技术应用于雪峰山特长隧道工程平面测量基准建立的方法,分析了GPS控制网的观测质量,并就GPS控制测量误差对隧道横向贯通误差的影响值进行了估算。  相似文献