增量破坏型机动安定性分析方法及其应用

根据避免累积塑性变形发生的安定准则，构造了相应的安定性数值求解方法，进而用于确定海洋平台地基的安定荷载上限近似解，为评价地基在复杂变值荷载作用下的承载力提供了依据。     

The diffraction of linear waves by a uniform vertical cylinder with cosine-type radial perturbations

The interaction of linear waves with a uniform, bottom-mounted, surface-piercing cylinder whose diameter exhibits a cosine-type variation is investigated. Two solution methods are presented. One method is based on a perturbation theory, using a perturbation parameter defined in terms of the surface geometry of the cylinder. The analysis includes terms up to the first-order in this parameter, where the zeroth-order solution corresponds to a circular cylinder. The velocity potentials at the zeroth and first orders are expressed as eigenfunction expansions involving unknown coefficients that are subsequently determined through the cylinder boundary conditions. The second method is based on Green's theorem and gives rise to an integral equation for the fluid velocity potential on the cylinder surface. A comparison between the results of these two methods has proved that they are in good agreement for small values of the perturbation parameter. Numerical results are presented that illustrate the influence of the magnitude and frequency of these perturbations on the resulting hydrodynamic force and the wave runup on the cylinder.     

不变子空间上特征值的摄动(英文)

本文推广Wielandt—Hoffman定理而得到如下结果:定理1: 设A=X_Adiag(λ_1~((A)),…,λ_n~((A)))X_A~(-1),Q_1∈C~(n×m),T=X_Tdiag万吨(λ_1~((T)),…,λ_m~((T)))X_T~(-1),m≤n。那么,存在1,2,…,n的某个排列π(1),…,π(n)使得:其中,K_2(C)=‖C‖_2‖C~(-1)‖_2,‖‖_2及‖‖_F分别代表矩阵的谱范数和Frobcnius范数,σ_(min)(Q_1)是矩阵Q_1的最小奇异值。     

Dynamic Response of Ocean Trestle to Horizontal Impact of Moving Mass

Based on the Winkler hypothesis, a model for analysis of the flexural response of an ocean trestle embedded in layered soil to horizontal impact of a moving mass is developed. By use of the transfer matrix in time domain, one can calculate the flexural dynamic response of a single pile. Then, by use of the boundary conditions of piles at the pile top, the dynamic response of the structure is analyzed. By use of the model proposed in this paper, the interactive force between the moving mass and the structure can be computed based on Work' s kinetic energy theorem and Newton iterative method. Thus the approach does not have to assume the interactive force, while the traditional method have to. The approach more accords with the engineering practice than the traditional method and it is convenient for engineering design.     

Three-Dimensional Instability of Flow Around Two Circular Cylinders in Tandem Arrangement

The spatial evolution of vortices and transition to three-dimensionality in the wake of two circular cylinders in tandem arrangement have been numerically studied. An improved virtual body method developed from the virtual boundary method is used here. A Reynolds number range between 220 and 270 has been considered, and the spacing between two cylinders is selected as L/D = 3 and L/D = 3.5. When L/D = 3, the secondary vortices of Mode-A are seen to appear at Re = 240 and persist over the range of the Reynolds number of 240 - 270. When L/D = 3.5, the similar critical Reynolds number has been found at Re = 250. No obvious discontinuity has been found in the Strouhal-Reynolds number relationship, and this is different from three-dimensional flow around a single cylinder at the critical Reynolds number. The spanwise wavelength is about four times the diameter of the cylinder, and it is the characteristic wavelength for ModeA instability. This paper can give some foremost insight into the three-dimensional instability of flow by complicated geometrical configuration.     

Analysis of Wave Directional Spreading by Bayesian Parameter Estimation

A spatial array of wave gauges installed on an observatoion platform has been designed and arranged to measure the lo-cal features of winter monsoon directional waves off Taishi coast of Taiwan. A new method, named the Bayesian Parameter Estimation Method(BPEM) , is developed and adopted to determine the main direction and the directional spreading parame-ter of directional spectra. The BPEM could be considered as a regression analysis to find the maximum joint probability of parameters, which best approximates the observed data from the Bayesian viewpoint. The result of the analysis of field wave data demonstrates the highly dependency of the characteristics of normalized directional spreading on the wave age. The Mit-suyasu type empirical formula of directional spectrum is therefore modified to be representative of monsoon wave field. More-over, it is suggested that Smax could be expressed as a function of wave steepness. The values of Smax decrease with increas-ing steepness. Finally, a local directi     

折线型滑面边坡稳定系数计算的极限分析上限解

从极限分析原理入手,以堆积型边坡作为对象,研究了折线型滑面边坡稳定分析计算的极限分析方法,提出了折线型滑面边坡稳定系数计算的极限分析模型,并在虚功率原理的基础上推导得到了稳定系数计算的极限分析上限解。该方法考虑了折线滑面和垂直速度间断面上的内能耗散作用,考虑了边坡自重荷载、铅直向附加荷载所做的外功率作用,能计算折线型滑面堆积体边坡的稳定性计算问题。以三峡库区三马山滑坡为工程实例进行了稳定性分析计算,并与不平衡推力法的计算结果进行了比较,对本文的方法进行了验证。     

苏锡常地区含水层结构和地下水位的虚拟表达

由于三维地质结构模型和地下水面(包括潜水水面和承压水水面)模型开展地面沉降机理研究的重要基础,因此,本次利用Visual C 和OpenGL(Open Graphics Library)将苏州—无锡—常州(简称苏锡常)地区第四系含水层结构和地下水位形态进行三维虚拟表达,创建了酷似于实际情况的地下水赋存环境(三维地质结构模型),并在该环境中添加了各含水层的水位线。研究者可交互操作于该虚拟环境,并能够直观形象地了解研究区内的水文地质情况(各地层间的空间分布及岩性特征、含水层间的补给关系及地下水位的动态过程等),从而获得身临其境的感受,为进行地面沉降机理研究提供一个基础性的辅助方法。     

基于泊松定理的重磁异常分析方法及应用

从泊松定理出发进行公式推导和分析,阐述了重磁异常的对应分析3个参数的物理意义,并认为在区域重磁数据解释时,对应分析得到的截距是在去掉感磁背景和与重力异常线性相关部分异常的剩磁异常的贡献,为其应用提供了基础。分析了重磁异常解释中泊松定理的作用,并通过具体的实例分析了基于泊松定理来确定地质体总磁化方向及其在分析火山岩活动中的作用。     

基于钻孔数据的地层三维建模与可视化研究

地质体三维建模是地学信息系统核心课题之一,对现有建模方法进行分析,结合地层特点,提出首先引入虚拟钻孔,利用Kriging插值方法建立地层三维模型;其次把虚拟钻孔参数的调试结果及专家知识等资料在建模流程中予以充分体现,从而建立相对精确的三维地层模型;最后基于本文建模方法开发了一个三维地层模型,并用实际资料进行了验证,能有效满足工程需求。