基于反演的衰减补偿方法(英文)

提高地震资料分辨率的一个有效途径就是衰减补偿,通过对地震波的衰减和频散效应进行校正,提高地震资料的分辨率。常规衰减补偿方法都是基于波场延拓的反Q滤波方法。本文利用Futterman衰减模型,导出了一种衰减介质中合成地震记录的计算方法,在此基础上将衰减补偿问题归结为一个Fredholm积分方程反问题,利用反演方法来实现衰减补偿。针对衰减补偿问题的不稳定性,利用Tikhonov正则化方法提高反演过程的稳定性,数值模拟资料和实际资料处理结果验证了方法的有效性。     

A diagnostic analysis of the weakening of West Pacific subtropical anticyclone during the period of South China Sea summer monsoon onset in 1998

The onset of South China Sea summer monsoon in 1998 occurred on May 21st. Using the U.S. National Centers for Environmental Prediction reanalysis data, this paper examines the physical process of the weakening of a subtropical anticyclone in West Pacific during the onset period using the Zwack-Okossi vorticity equation. Results show that during the pre-onset period, the positive vorticity advection in front of an upper tropospheric trough was the most dominant physical mechanism for the increase of the cyclonic vorticity on the 850-hPa layer over the South China Sea and its nearby region. The secondary contribution to the increase of the cyclonic vorticity was the warm-air advection. After the onset, the magnitude of the latent-heat warming term rapidly increased and its effect on the increase of the cyclonic vorticity was about the same as the positive-vorticity advection. The adiabatic term and divergence term contributed negatively to the increase of the cyclonic vorticity most of the time. Thus, the positive vorticity advection is the most important physical mechanism for the weakening of the West Pacific subtropical anticyclone over the South China Sea during the onset period.     

复杂地表边界元-体积元波动方程数值模拟

复杂近地表引起来自深部构造的地震反射信号振幅和相位的异常变化,是影响复杂近地表地区地震资料品质的主要原因.本文采用边界元-体积元方法,通过求解含复杂地表的波动积分方程,来模拟地震波在复杂近地表构造中的传播.其中,边界元法模拟地形起伏和表层地质结构对地震波传播的影响;体积元法模拟起伏地表下非均质低降速层的影响.与其他数值...     

一个近似的VTI介质声波方程

声学近似是提高各向异性介质准纵波数值模拟和偏移处理计算速度的有效方法之一.为了获得VTI(具有垂直对称轴的横向各向同性)介质声波方程,根据VTI介质的精确相速度表达式,用待定系数法简化其中的根号项,得到一个近似相速度公式,由此公式通过反Fourier变换推导出一个时间二阶、空间四阶偏微分方程.定量相速度计算表明,当Th...     

Infiltration in unsaturated soils – An analytical approach

An approximate analytical solution has been established for the well known Richards’ equation for unsaturated flow of transports in soils. Despite the importance of Richards’ equation in geotechnical and geoenvironmental applications, most solutions to the problem are generally based on numerical methods often having limitations in application. It is therefore advantageous to explore analytical solutions to the problem. The proposed solution is based on homotopy analysis method (HAM). The method is superior over traditional perturbation techniques in a sense that it is not dependent on the assumption of a small parameter as the initial step. Several simple cases have been explored to describe the application of HAM to Richards’ equation. The results obtained by HAM are also compared with existing solutions to demonstrate the accuracy of the proposed method.     

基于单程波真振幅分步傅里叶叠前深度偏移方法

这里将单程波真振幅方程与分步傅里叶算子（SSF）相结合,同时还结合了保幅算法和分步傅里叶算法的优点,因此该方法具有计算量小,占内存少,能处理横向变化的速度等优点。并且克服了傅里叶有限差分方法偏移后的振幅都有很大的偏差的不足。与目前广泛应用的常规的分步有限差分叠前深度偏移相比,具有成像精度高,保持地震波动力学特征等优点。在Marmousi模型上成功地进行了真振幅分步傅里叠前深度偏移处理,取得了理想的成像效果。     

莱州湾南岸地下卤水水位动态变化与开采量关系研究

由于多年来大量开采地下卤水,莱州湾南岸已经形成多个地下卤水降落漏斗.该文根据区内盐场水位长期观测资料,较系统地分析了地下卤水水位动态变化规律,查明了卤水水位与开采量的关系,建立了区内卤水水位与开采量相关关系方程.通过分析说明开采对水位的影响,为改善区内地质环境,合理利用卤水资源提供了科学依据.     

基于抛物型缓坡方程模拟近岸植被区波浪传播

植被对波浪传播运动有重要影响。考虑近岸波浪在植被区传播中的折射、绕射、破碎及植被引起的波能耗损效应,基于抛物型缓坡方程建立了模拟近岸植被区波浪传播的数学模型,对模型进行了数值模拟验证,采用数值模拟试验分析了植被对波浪传播的影响。数值模拟结果表明,波浪在近岸植被区传播时,随着植被密度和植被高度的增加,波浪传播中的波高衰减增大,波能耗损增加;不同周期波浪在植被区传播中的波高衰减过程也明显不同。     

Numerical simulation of wave-induced currents combined with parabolic mild-slope equation in curvilinear coordinates

Researches on breaking-induced currents by waves are summarized firstly in this paper. Then, a combined numerical model in orthogonal curvilinear coordinates is presented to simulate wave-induced current in areas with curved boundary or irregular coastline. The proposed wave-induced current model includes a nearshore current module established through orthogonal curvilinear transformation form of shallow water equations and a wave module based on the curvilinear parabolic approximation wave equation. The wave module actually serves as the driving force to provide the current module with required radiation stresses. The Crank-Nicolson finite difference scheme and the alternating directions implicit method are used to solve the wave and current module, respectively. The established surf zone currents model is validated by two numerical experiments about longshore currents and rip currents in basins with rip channel and breakwater. The numerical results are compared with the measured data and published numerical results.     

德州市城区地热水动态与开采量关系

德州市城区多年来因地热水大量开采,地热水位持续下降,并形成了以德州市城区为中心的地热水降落漏斗。根据区内馆陶组热储多年地热水动态与开采量进行分析研究,查明了区内地热水动态与开采量的相互关系,进一步揭示了人为活动的影响,建立了区内地热水动态与开采量相关方程,并通过方程曲线态势分析,提出了区内地热集中开采区馆陶组热储地热水预警开采量,为区内地热资源的可持续开发利用提供了科学依据。