中国大陆及其周边块体的现时运动、变形及其动力学解释

运用块体不连续变形分析方法 ,对利用GPS测量数据解算中国大陆及其周边块体的位移进行分析。结果显示 ,除块体 2、10、13为近东西方向的运动 ,块体 15为近北东向的运动外 ,其余块体均朝南东或南东东方向运动。同时 ,各块体还以各自的角速度绕其重心旋转。整个研究区在南北方向是压缩的 ,所得的最大主应力方向与利用震源机制解与原地应力测量的结果总的来说大体一致。最后 ,对产生中国大陆及周边块体运动与变形的动力源进行了讨论     

Sensitivity of GPS and GLONASS orbits with respect to resonant geopotential parameters

The Center for Orbit Determination in Europe (CODE) has been involved in the processing of combined GPS/GLONASS data during the International GLONASS Experiment (IGEX). The resulting precise orbits were analyzed using the program SORBDT. Introducing one satellites positions as pseudo-observations, the program is capable of fitting orbital arcs through these positions using an orbit improvement procedure based on the numerical integration of the satellites orbit and its partial derivative with respect to the orbit parameters. For this study, the program was enhanced to estimate selected parameters of the Earths gravity field. The orbital periods of the GPS satellites are —in contrast to those of the GLONASS satellites – 2:1 commensurable (P _Sid:P _GPS) with the rotation period of the Earth. Therefore, resonance effects of the satellite motion with terms of the geopotential occur and they influence the estimation of these parameters. A sensitivity study of the GPS and GLONASS orbits with respect to the geopotential coefficients reveals that the correlations between different geopotential coefficients and the correlations of geopotential coefficients with other orbit parameters, in particular with solar radiation pressure parameters, are the crucial issues in this context. The estimation of the resonant geopotential terms is, in the case of GPS, hindered by correlations with the simultaneously estimated radiation pressure parameters. In the GLONASS case, arc lengths of several days allow the decorrelation of the two parameter types. The formal errors of the estimates based on the GLONASS orbits are a factor of 5 to 10 smaller for all resonant terms. AcknowledgmentsThe authors would like to thank all the organizations involved in the IGS and the IGEX campaign, in particular those operating an IGS or IGEX observation site and providing the indispensable data for precise orbit determination.     

基于抽水试验的土体渗透性耦合响应模型研究

土体中大量降排水的过程实际上是土体中有效应力增长的过程。通过对抽水试验中土体渗透系数的回归分析,建立了渗透系数与有效应力增量之间的耦合响应模型关系,说明降排水过程中土体渗透系数是呈非线性变化的。     

Dynamical Initialization of Boundary-Layer Data

A procedure for the dynamic initialization of wind and temperature fields within the atmospheric boundary layer (ABL) is presented. The procedure uses transilient turbulence theory to assess the turbulent fluxes from observed wind and temperature data, which are used to estimate the eddy transfer coefficients, so enabling a local closure ABL model to be integrated forward in time to a new steady state. The method has been applied to initialize kytoon data taken at Kharagpur (22.3° N, 87.2° E) during the MONTBLEX field programme. Results of a case study for 17 June 1990 are discussed.     

各向异性介质中的AVO

分析了横向各向同性和方位各向异性介质的本构关系,由此讨论弹性波在两种各向异性介质中的传播特点,提出可表征这两种介质各向异性程度的广义参数．以此为基础讨论了两种各向异性介质中存在水平界面时的反射系数近似式,将Dely等人推导的横向各向同性介质中的反射系数公式推广到方位各向异性介质的主轴方向上．根据算例讨论修正的Banik和Thomsen的近似式,着重分析两种各向异性介质中的AVO关系及其对实际勘探的影响和指导意义．     

Binary coefficients: A theoretical and empirical study

Binary coefficients can be assigned to several categories on the basis of algebraic and conceptual properties. The phi coefficient of association is related algebraically to the chi-square statistic for 2-by-2 contingency tables, and use of this coefficient in cluster analysis permits the objective, nonarbitrary partitioning of objects among groups on the basis of previously selected levels of significant, positive association. Similarity, matching, and distance coefficients possess neither conceptual nor operational statistical meaning for many geological data sets. The weighted pair group method and flexible clustering strategy may give an overly conservative partitioning of objects among groups. Clustering by the unweighted pair group method, using the phi coefficient, is recommended for the analysis of biostratigraphic and paleoecologic presence—absence data.     

Three‐parameter discontinuous distributions for hydrological samples with zero values

A consistent approach to the frequency analysis of hydrologic data in arid and semiarid regions, i.e. the data series containing several zero values (e.g. monthly precipitation in dry seasons, annual peak flow discharges, etc.), requires using discontinuous probability distribution functions. Such an approach has received relatively limited attention. Along the lines of physically based models, the extensions of the Muskingum‐based models to three parameter forms are considered. Using 44 peak flow series from the USGS data bank, the fitting ability of four three‐parameter models was investigated: (1) the Dirac delta combined with Gamma distribution; (2) the Dirac delta combined with two‐parameter generalized Pareto distribution; (3) the Dirac delta combined with two‐parameter Weibull (DWe) distribution; (4) the kinematic diffusion with one additional parameter that controls the probability of the zero event (KD3). The goodness of fit of the models was assessed and compared both by evaluation of discrepancies between the results of both estimation methods (i.e. the method of moments (MOM) and the maximum likelihood method (MLM)) and using the log of likelihood function as a criterion. In most cases, the DWe distribution with MLM‐estimated parameters showed the best fit of all the three‐parameter models. Copyright © 2005 John Wiley & Sons, Ltd.     

Generalized Laplace coefficients and Newcomb derivatives

It is shown how the generalized Laplace coefficients can be employed to deduce explicit formulas for ordinary and Newcomb derivatives of the Laplace coefficients.      

基于分层EOF的深海声速剖面时变特征建模

针对目前局部海域小时间尺度声速场建模方法未顾及不同深度区间内声速变化规律的问题,本文根据实测深海声速剖面的统计特征,提出了声速剖面分层方法,并进一步基于经验正交函数（Empirical Orthogonal Function, EOF）提出了局部小时间尺度的声速剖面分层时变模型构建方法。利用南海实测全海深声速剖面数据,分析了分层EOF第一模态系数和等效平均声速的日变化特征,并比较了不同拟合模型的精度。最后,利用试验海区的温度和潮汐数据分析了声速剖面周期变化的影响因素。结果表明： ①声速剖面分层EOF第一模态系数及等效平均声速具有日周期变化特征,上层声速日周期变化特征不明显,中层声速日周期变化特征较明显,下层声速变化较小但仍具有日周期变化特征;②局部海域小时间尺度声速拟合应考虑长期变化项的影响;③试验海区声速剖面EOF第一模态系数变化与温度显著相关,提取的声速剖面时变特征与海区潮汐周期特征基本吻合。