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。     

Numerical simulation of seismic wave propagation in complex media by convolutional differentiator

We apply the forward modeling algorithm constituted by the convolutional Forsyte polynomial differentiator pro-posed by former worker to seismic wave simulation of complex heterogeneous media and compare the efficiency and accuracy between this method and other seismic simulation methods such as finite difference and pseudospec-tral method. Numerical experiments demonstrate that the algorithm constituted by convolutional Forsyte polyno-mial differentiator has high efficiency and accuracy and needs less computational resources, so it is a numerical modeling method with much potential.     

Hybrid formulation of operator splitting (OS) and Newmark‐β methods for collaborative structural analysis (CSA)

A collaborative structural analysis (CSA) system is developed, which is capable of performing highly sophisticated structural analyses utilizing beneficial features of existing individual structural analysis programs. In the system, the global equations of motion for the overall structural system are formulated in the host program. Some substructures, whose behaviors are relatively simple, are directly solved in the host program, whereas those having complex behavior are analyzed by the station programs. A time‐consuming static condensation procedure is needed for the substructures analyzed by the station programs if adopting an implicit integration scheme. The operator splitting (OS) method, which does not require tangential stiffness, can be used to improve the system efficiency. To this end, a hybrid formulation of the Newmark‐β and OS methods is proposed, and a CSA scheme based on the hybrid formulation is developed. In the CSA system adopting the hybrid formulation, the degrees of freedom whose tangential stiffness are unavailable are formulated by the OS method, whereas the rest are still formulated by the commonly used Newmark‐β method. Using the system, analyses of a three‐story‐braced steel moment‐resisting frame are conducted. In the analyses, the column bases are analyzed using the commercial finite element method software ABAQUS, and the remaining structural elements are analyzed using a frame analysis program called NETLYS. Results suggest that the hybrid formulation is very effective for the CSA system. Copyright © 2008 John Wiley & Sons, Ltd.     

利用CFP技术解决复杂近地表问题综述

复杂近地表条件会降低地震数据的质量,通常采用基于地表一致性的时移静校正消除其影响.但静校正与速度是密不可分的,而确定复杂近地表速度是非常困难的.基于CFP技术处理复杂近地表问题时避免了对速度的直接操作,使得静校正和速度的确定相互独立.首先根据叠前数据估算出波场的传播算子,然后依据等时原理在DTS模板中进行算子更新,再用这些更新的算子重建基准面和实现近地表单程时间成像.获得正确的算子振幅也是重建基准面的关键.     

基于Min-Max算子的遥感影像线状地物提取

将模糊数学中极小-极大算子的概念引入到遥感影像线状地物的半自动提取中。实验结果表明该方法能够有效地克服影像上各种噪声的影响,提取速度较快并具有较强的鲁棒性。     

无单元法布点优化的一种新方法

研究了无单元法中单个影响域内的布点形式对误差的影响,提出了半径权值的概念。在经过充分的数值计算后,给出在半径权值对无单元法插值结果的精度的影响值的大小。研究对优化无单元法的节点布置、减小模拟误差有很大的作用,并且使得影响域的大小不再依靠点数的多少来确定,避免了影响域过大的情况和为了单个影响域内有足够多的插值点而使得整体插值点数目过多的弊端。运用单个区域内的插值点健康度的理论,研究了整个区域布点对无单元法模拟函数--滑动最小二乘法模拟精度的影响,并运用遗传算法对整个布点区域上的插值点进行了优化,给出了区域上的优化值。通过一个实例,得到一个具有普遍意义的插值点优化值与插值点密度的关系,并给出无单元法布点的一般性原则。     

Nonlinear coupled analysis of a single point mooring system

Coupled effects on a single point mooring(SPM) system subjected to the combined action of wind,waves and current are studied in this paper. Due to the complicatedness of the sea state and the huge size of the vessel,physical experimental study is both time consuming and uneconomical,whereas the numerical study is cost-effective and DNV software provides powerful SESAM software in solving the issues. This paper focuses on the modeling process of the SPM system,catenary equilibrium calculation,static analysis of the vessel in three different scenarios,and dynamic response simulation of the SPM system under environmental excitations. The three scenarios in study are as follows:the SPM is under the combined function of(a) wind,waves and current,(b) wind and waves,(c) current and waves. They are so set that one can compare the contributions of different types of loads in both static and dynamic studies. Numerical study shows that wind and current are the two major factors contributing to the mooring line tension,and surge and sway are the two dominant motions of the moored vessel subjected to environmental excitations.     

一种基于点特征的高精度图像配准方法

提出了一种基于点特征的多源图像高精度配准方法。通过在遥感影像上提取密集特征点,利用多种方法结合进行严格匹配获得同名点对。通过构建不规则三角网分割影像,再利用仿射变换模型实现每个三角形的配准。实验证明了该方法的有效性和较高的适用性。     

Underground water quality model inversion of genetic algorithm

The underground water qualitymodel with non-linear inversion problem is illposed, and boils down to solving the minimum of nonlinear function. Genetic algorithms are adopted in a number of individuals of groups by iterative search to find the optimal solution of the problem, the encoding strings as its operational objective, and achieving the iterative calculations by the genetic operators. It is an effective method of inverse problems of groundwater, with incomparable advantages and practical significances.     

机载碘化银发生器燃烧室残留物成分分析

通过对碘化银发生器残留物样本化学分析,残留物附着规律及其成因研究,最后提出了减少残留物的对策。