乌恰地震加速度记录特征研究

研究了1985年乌恰余震取得的加速度记录,从地质及地球物理的角度探讨一些加速度异常点。分析了记录的峰值加速度与震害及场地烈度的对应关系。对比了竖向和水平向加速度、速度反应谱及谱与震级的变化特征。     

Development of the instantaneous unit hydrograph using stochastic differential equations

Recognizing that simple watershed conceptual models such as the Nash cascade ofn equal linear reservoirs continue to be reasonable means to approximate the Instantaneous Unit Hydrograph (IUH), it is natural to accept that random errors generated by climatological variability of data used in fitting an imprecise conceptual model will produce an IUH which is random itself. It is desirable to define the random properties of the IUH in a watershed in order to have a more realistic hydrologic application of this important function. Since in this case the IUH results from a series of differential equations where one or more of the uncertain parameters is treated in stochastic terms, then the statistical properties of the IUH are best described by the solution of the corresponding Stochastic Differential Equations (SDE's). This article attempts to present a methodology to derive the IUH in a small watershed by combining a classical conceptual model with the theory of SDE's. The procedure is illustrated with the application to the Middle Thames River, Ontario, Canada, and the model is verified by the comparison of the simulated statistical measures of the IUH with the corresponding observed ones with good agreement.     

斜压半地转模式中的非频散周期解

给出了３个通量矢量，从而将非线性平流项表示为３个通量矢量的旋度和散度，它们分别对纬向风和经向风的低频加速产生贡献。经过卷积运算，还建立了低频变化的动力学模型。给出了通量矢量Ｅ．、Ｇ１．、Ｇ２．等的空间分布及其相应的流函数与势函数的水平分布和时间演变，从而指出，瞬变扰动间的相互作用对流动具有低频加速作用。     

河西—祁连山地区近期形变场演化特征与孕震构造模式

本文通过对河西－祁山地区近２０年形变场演化特征的分析，提出了代表该区区域应力松驰、岩石圈底部软流层对流加速以及地壳中上部应力强化与强震孕育三种应力状态的特征性形变图象，文章还通过典型强震构造组合特征、形变场特征的分析，提出了该区北西西、北东向两组构造的组合孕震模式，并利用上述孕震模式对该区近期强震危险地点进行了初步判定。     

A review on stochastic differential equations for applications in hydrology

Fundamentals of the theory of stochastic calculus and stochastic differential equations (SDE's) which are finding increasing application in water resources engineering are reviewed. The basics of probability theory, mean square calculus and the Wiener, white Gaussian and compound Poisson processes are given in preparation for a discussion of the general Itô SDE with drift, diffusion and jump discontinuity terms driven by Gaussian white noise and compound Poissionian impulses. Also discussed are stochastic integration and the derivation of moment equations via the Itô differential rule. The lierature of SDE's is reviewed with an emphasis on the more accessible sources.     

Density-dependent dispersion in heterogeneous porous media Part I: A numerical study

In this paper, we describe carefully conducted numerical experiments, in which a dense salt solution vertically displaces fresh water in a stable manner. The two-dimensional porous media are weakly heterogeneous at a small scale. The purpose of these simulations, conducted for a range of density differences, is to obtain accurate concentration profiles that can be used to validate nonlinear models for high-concentration-gradient dispersion. In this part we focus on convergence of the computations, in numerical and statistical sense, to ensure that the uncertainty in the results is small enough.Concentration variances are computed, which give estimates of the uncertainty in local concentration values. These local variations decrease with increasing density contrast. For tracer transport, obtained longitudinal dispersivities are in accordance with analytical findings. In the case of high-density contrasts, stabilizing gravity forces counteract the growth of dispersive fingers, decreasing the effective width of the transition zone. For small log-permeability variances, the decrease of the apparent dispersivity that is found is in agreement with laboratory results for homogeneous columns.     

Acceleration response modification factors for nonstructural components attached to inelastic moment‐resisting frame structures

A statistical analysis of the peak acceleration demands for nonstructural components (NSCs) supported on a variety of stiff and flexible inelastic regular moment‐resisting frame structures with periods from 0.3 to 3.0 s exposed to 40 far‐field ground motions is presented. Peak component acceleration (PCA) demands were quantified based on the floor response spectrum (FRS) method without considering dynamic interaction effects. This study evaluated the main factors that influence the amplification or decrease of FRS values caused by inelasticity in the primary structure in three distinct spectral regions namely long‐period, fundamental‐period, and short‐period region. The amplification or decrease of peak elastic acceleration demands depends on the location of the NSC in the supporting structure, periods of the component and building, damping ratio of the component, and level of inelasticity of the supporting structure. While FRS values at the initial modal periods of the supporting structure are reduced due to inelastic action in the primary structure, the region between the modal periods experiences an increase in PCA demands. A parameter denoted as acceleration response modification factor (R_acc) was proposed to quantify this reduction/increase in PCA demands. Copyright © 2007 John Wiley & Sons, Ltd.     

Stochastic assessment of GPS carrier phase measurements for precise static relative positioning

 Global positioning system (GPS) carrier phase measurements are used in all precise static relative positioning applications. The GPS carrier phase measurements are generally processed using the least-squares method, for which both functional and stochastic models need to be carefully defined. Whilst the functional model for precise GPS positioning is well documented in the literature, realistic stochastic modelling for the GPS carrier phase measurements is still both a controversial topic and a difficult task to accomplish in practice. The common practice of assuming that the raw GPS measurements are statistically independent in space and time, and have the same accuracy, is certainly not realistic. Any mis-specification in the stochastic model will inevitably lead to unreliable positioning results. A stochastic assessment procedure has been developed to take into account the heteroscedastic, space- and time-correlated error structure of the GPS measurements. Test results indicate that the reliability of the estimated positioning results is improved by applying the developed stochastic assessment procedure. In addition, the quality of ambiguity resolution can be more realistically evaluated. Received: 13 February 2001 / Accepted: 3 September 2001     

区调提速的紧迫性和可行性

区域地质调查（区调）是国家重要的基础性工作。近年来，随着我国经济、社会的快速发，调整区调工作布局，加快区调工作步伐已迫在眉睫。本从国民经济、社会发展的需求和国家“十五”计划的要求出发，分析了全国区调工作的现状和发展趋势，对依靠科技进步，调整区调部署、加快区调进度的紧迫性、可行性及目标任务进行了论述，指出了尽快将区调工作纳入全面服务社会的轨道、2005年优先安排并完成青藏高原空白区1；25万区调工作、2010年前全面完成全国中比例尺区调任务并出版中国第一套相关基础地质系列图件的基本思路。章特别指出，区调提速一定要确保野外填图的质量，工作部署一定要坚持实事求是的原则。要依靠计算机、遥感等高新技术实现区调提速，要在提速过程中实现区调工作主流程的信息化。     

GPS定位中对流层折射估计研究

本文首先讨论了ＧＰＳ相对定位中的对流层折射２估计的单参数方法，多参数方法，分估线性方法和随机过程方法。论证了其它方法都是随机过程方法的近似。为了用随机过程模拟对流折射，建立了一种最小二乘递推算法。在此基础上，在ＧＡＭＩＴ软件中统一实现了以各种对流层折射估计方法。最后给出并分析了不同方法所获得的结果。