Efficient global matrix approach to the computation of synthetic seismograms

Summary. A numerically efficient global matrix approach to the solution of the wave equation in horizontally stratified environments is presented. The field in each layer is expressed as a superposition of the field produced by the sources within the layer and an unknown field satisfying the homogeneous wave equations, both expressed as integral representations in the horizontal wavenumber. The boundary conditions to be satisfied at each interface then yield a linear system of equations in the unknown wavefield amplitudes, to be satisfied at each horizontal wavenumber. As an alternative to the traditional propagator matrix approaches, the solution technique presented here yields both improved efficiency and versatility. Its global nature makes it well suited to problems involving many receivers in range as well as depth and to calculations of both stresses and particle velocities. The global solution technique is developed in close analogy to the finite element method, thereby reducing the number of arithmetic operations to a minimum and making the resulting computer code very efficient in terms of computation time. These features are illustrated by a number of numerical examples from both crustal and exploration seismology.     

Numerical Study on Vortices in the Middle Layer of Flow around a Large Mountain under Rotating Stratified Conditions

Generation of cyclonic vortices in the middle layer of flow around a large mountain like Tibet and Rocky was investigated by means of a 3-D nonhydrostatic meteorological prognostic model. Special attention was paid to the effects of the earth’s rotation and stratification on the vortices detached successively from the slope of a high and large horizontal scale mountain. It was found the successive formation and detachment of such ‘von Karman-like vortices’ occurred in the flow regime at high Rossby numbers Ro and low Froude numbers Fr. It was successfully divided by the criterion of baroclinic instability. This means that if the condition is unstable baroclinically, a lee vortex is destabilized into a three-dimensional one, while under baroclinically stable conditions the lee vortex with vertical axis retains its standing structure and remains long lasting in the middle layer.     

热带气旋发生、发展的不稳定理论

本文在正压无辐散的条件下,讨论了东、西风不连续面上的正压不稳定性。研究指出:这种界面上的扰动总是不稳定的,从而说明了热带气旋常在赤道辐合带(ITCZ)上形成的原因。本文又在考虑了热带气旋内部的层结和基本气流的条件下,讨论了热带气旋发展的热力学和动力学条件。研究指出:层结稳定度和惯性稳定度同时影响热带气旋的发展.当两者都稳定时,热带气旋不发展;当两者之一不稳定时,热带气旋有可能发展;当n~2I~2 (μ~2/a)~2N~2<0时,热带气旋一定发展。     

由正入射遥测海底介质参数方法初探

通过数值模拟计算发现，对于分层有吸收海底，在层厚已知的条件下，除最下面的介质以外．有可能利用垂直入射的脉冲声波遥测各层的密度、声速与吸收系数。此法的要点是，根据入射波和层参数的假设值算得反射信号，与实际反射信号比较；然后改变参数再作计算，直到误差最小为止．此时对应的层参数即为介质参数值实际的估计值。指出根据这种方法有可能实现以自适应方法遥测分层海底的介质参数。     

求解各向异性分层介质中水平电偶极辐射的实用方法

用矩阵对角化方法求解了在各向异性分层介质中水平电偶极的辐射问题 ,并引入“过渡矢量”,利用其传播特性求得定解 ,此方法简单实用 ,不要求相似变换矩阵归一化。作为应用 ,具体计算了电离层被加热产生的极低频源在几千公里范围水下不同深度远处接收场强的量级     

基于楼盘表和户型图的分层分户模型建设

随着智慧城市建设的不断升级,城市管理向精细化和智能化方向快速发展.分层分户模型可以承载更复杂、更立体、更详细、更精确的信息,以供全面综合管理、大数据分析和应急指挥使用.本文以"数字郑州三维地理信息及应用服务系统"项目建设实际情况为背景,探索和实现了在SuperMap GIS平台环境下,基于楼盘表提供的层户信息与户型图提供的分户信息,通过数字线划图进行建筑底面定位,利用地名地址将楼盘表和户型图与数字线划图进行关联挂接,并根据LiDAR点云数据的高度信息,快速自动化地建设郑州市800 km2内所有建筑物的分层分户模型的技术方法.进一步探索了通过模型成果与房管信息和公安户籍信息挂接,建立"以图管房、以房管人"的新管理模式,有效提升了政府管理和决策水平.本文提出的方法技术路线先进,实操性强,具有重要的应用推广价值.     

地理探测器：原理与展望

空间分异是自然和社会经济过程的空间表现,也是自亚里士多德以来人类认识自然的重要途径。地理探测器是探测空间分异性,以及揭示其背后驱动因子的一种新的统计学方法,此方法无线性假设,具有优雅的形式和明确的物理含义。基本思想是：假设研究区分为若干子区域,如果子区域的方差之和小于区域总方差,则存在空间分异性;如果两变量的空间分布趋于一致,则两者存在统计关联性。地理探测器q统计量,可用以度量空间分异性、探测解释因子、分析变量之间交互关系,已经在自然和社会科学多领域应用。本文阐述地理探测器的原理,并对其特点及应用进行了归纳总结,以利于读者方便灵活地使用地理探测器来认识、挖掘和利用空间分异性。     

NONLINEAR INERTIA—GRAVITY INTERNAL WAVE IN STRATIFIED FLUID

Based on the fundamental equations of geophysical fluid dynamics and on the consequence of verticaldensity stratification,travelling wave coordinates are used in this work to study the geometric topologicalstructures of nonlinear permanent wave in phase plane.Rigorous mathematical mechanics demonstratethat the solution of permanent solitary wave does not exist.Hamilton functions and "action-angle" varia-bles are used to express the travelling wave system in the simplest form and the analytic solution of the nonlinear inertia-gravity internal wave is obtained.     

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