The relation between the response spectrum and the phase diference spectrum

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较大地震破裂尺度的一种简单估算

通过对各向同性均匀介质中两个点源的波形传播的几何性质的分析，提出对较大地震的破裂尺度的估计，可以采用多个子事件的模拟，根据接收台站得到的子事件的视时间差的分布特征，判断震源的实际破裂方向和破裂尺度，甚至仅仅根据宽频带Ｐ波（组）的波形宽度就可进行近似的估算。     

用角差前方交会法配合光电测距快速定位桥墩

首次推导出角差前方交会的方式，在桥墩定位的施工现场，可简便、快速地求得持定点的坐标偏离值。该方法精度高，适用于各种定位，特别是深水桥墩浮运物的快速精密定位更具优越性。     

上海天文台的VLBI、SLR、GPS站的空间归心测量

上海天文台的余山VLBI、SLR和GPS站是国际上用以建立和维持地球参考系进行全球动力学研究的基准台站之一。联合应用这些空间测量,需要知道这三个站心间的三维相对位置。本文采用GPS技术及常规的方向、距离和精密水准测量对三个站进行了空间归心测量。介绍了布网、观测和计算方法,得到的归心结果在坐标分量上能达到2cm的外附精度。     

Seismic energy partitioning and scattering in laterally heterogeneous ocean crust

We present finite difference forward models of elastic wave propagation through laterally heterogeneous upper oceanic crust. The finite difference formulation is a 2-D solution to the elastic wave equation for heterogeneous media and implicitly calculatesP andSV propagation, compressional to shear conversion, interference effects and interface phenomena. Random velocity perturbations with Gaussian and self-similar autocorrelation functions and different correlation lengths (a) are presented which show different characteristics of secondary scattering. Heterogeneities scatter primary energy into secondary body waves and secondary Stoneley waves along the water-solid interface. The presence of a water-solid interface in the model allows for the existence of secondary Stoneley waves which account for much of the seafloor noise seen in the synthetic seismograms for the laterally heterogeneous models.Random incoherent secondary scattering generally increases aska (wavenumber,k, and correlation length,a) approaches one. Deterministic secondary scattering from larger heterogeneities is the dominant effect in the models aska increases above one. Secondary scattering also shows up as incoherence in the primary traces of the seisograms when compared to the laterally homogeneous case. Cross-correlation analysis of the initialP-diving wave arrival shows that, in general, the correlation between traces decreases aska approaches one. Also, because many different wave types exist for these marine models, the correlation between traces is range dependent, even for the laterally homogeneous case.     

Validation and error analysis of a strata modelling technique

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.     

岷江柏林下土壤养分特征及种群间差异分析

对现存于川西6个县的岷江柏林下土壤养分状况及其空间差异性比较研究表明，土壤表层（0～20em）有机质、全N、全P、碱解N、速效P、速效K和阳离子交换量均以马尔康居群最高，其次为金川、小金、丹巴居群，理县和茂县居群较低，土壤全K和土壤pH恰好相反，茂县居群较大，马尔康居群较小。从土壤的垂直变化看，除全K和土壤pH外，其它土壤养分均为表土层大于底土层。从相关性分析看，岷江柏林下土壤全N、全P、碱解N、速效P和CEC与土壤有机质呈极显著相关，土壤速效养分主要受全量养分控制，土壤养分指标地理空间差异较大，通过岷江柏林土壤养分指标的相关性分析，马尔康岷江柏居群土壤养分指标综合性能最好，其次为理县、金川、丹巴、小金岷江柏居群，最差的为茂县岷江柏居群。岷江柏林下养分差异是植被状况、地形条件、保护管理措施和人为干扰状况等多种因素综合作用的结果。     

不同用语能见度之间的差异

着重介绍各种能见度术语以及部分国家和国际组织因对能见度描述用语的不同而产生的差异，尤其是气象能见度同航空要求的能见度与跑道视程之间的不同。对于我国加入WTO后，航空界了解国际使用能见度的情况及如何和国际接轨有一定参考价值。     

单历元非差GPS定位函数模型

依据GPS测量原理，导出非差模糊度和双差模糊度，分析一省的组成与特性。原始非差GPS定位函数模型中，设计矩阵秩亏，非差模糊度不具备整数特性，故提出参数重整，将非差模糊度转换为双差模糊度，推出基于参数重整的单历元非差GPS定位函数模型。     

基于相拟性准则的SAR图像分割方法

提出一种以似然差函数作为相似性衡量标准的SAR图像分割方法。首先根据SAR图像的强度分布特性，通过仿真，发现两个具有相同分布的均匀区域合并成一个区域后，它们的似然差函数近似与区域的大小和均值无关，而仅与SAR图像的视数有关。在此基础上对两个相邻区域的似然差函数进行简化，获得它的概率密度函数的解析形式。选取一定的虚警率，计算出两个相邻区域之间存在边界的似然差函数的阈值。然后根据似然差函数和区域的形状的约束建立融合代价，使得所有可以融合的区域按照一定的顺序融合。当没有区域可以进一步融合时，就获得SAR图像的最终分割结果。