冰盖海洋中多孔海底结构上微小起伏边缘产生的波浪散射分析(英文)

Scattering of surface waves by the edge of a small undulation on a porous bed in an ocean of finite depth, where the free surface has an ice-cover being modelled as an elastic plate of very small thickness, is investigated within the framework of linearized water wave theory. The effect of surface tension at the surface below the ice-cover is neglected. There exists only one wave number propagating at just below the ice-cover. A perturbation analysis is employed to solve the boundary value problem governed by Laplace's equation by a method based on Green's integral theorem with the introduction of appropriate Green's function and thereby evaluating the reflection and transmission coefficients approximately up to first order. A patch of sinusoidal ripples is considered as an example and the related coefficients are determined.     

基于理论的船舶主机冷却水控制系统的设计

摘要本文对船舶主柴油机缸套冷却水系统的传热机理进行了分析,建立了船舶主柴油机缸套冷却水系统的动态热力数学模型。由于系统的参数具有不确定性,并针对目前船舶主柴油机缸套冷却水系统惯性较大,缸套冷却水出口温度经常超调的特点,设计了该系统的H∞控制器。通过仿真发现所设计的H∞控制器能有效地提高系统的动态精确度和抑制扰动的能力。     

砂土路基湿化变形和稳定性的可靠度分析

针对某高速公路砂土路基浸水湿化的情况,在现场钻取土样进行试验得到土性非线性参数统计结果的基础上,将参数变异性较大的土性参数K、Kb模拟为宽平稳高斯随机场;应用二维随机场局部平均理论和Duncan-Chang模型,建立二阶非线性摄动随机有限元分析模型,对该高速公路砂土路基的湿化变形和稳定性进行可靠度分析。结果表明:砂土湿化后将发生附加沉降变形,土性参数的变异引起路基沉降的变异性较小;虽然砂土湿化后其土性参数将降低,但路基稳定性的可靠度指标仍然较大,发生破坏的可能性较小。     

中承式拱桥吊索损伤对吊索系静张力的影响

基于中承式拱桥的有限元建模,考虑到吊索损伤对吊索拉伸刚度的影响,运用一阶矩阵摄动理论,采用刚性拱模型,研究了中承式拱桥吊索损伤对吊索系静张力的影响,导出了吊索系张力矢量因损伤变化的表达式,并用工程实例进行计算机仿真研究。研究结果表明:吊索的损伤会引起吊索系静张力的重新分布,即引起损伤吊索自身静张力的减小及邻近吊索静张力增大,随着损伤的增大,这种变化也逐渐增大;损伤大小与吊索静张力的变化呈近似的线性关系。这一结果对中承式拱桥吊索损伤的检测有实际参考价值。     

A Class of Shock Solutions for the Semilinear Singularly Perturbed Boundary Value Problem

The shock solution for the semilinear singularly perturbed two-point boundary value problem was studied. Under suitable conditions and using the theory of differential inequalities, the existence and asymptotic behavior of the solution for the original boundary value problems are discussed. The uniformly effective asymptotic expansion and estimation of solution u(x, ε) were obtained.     

基于摄动思想的传递闭包聚类法的分析与应用

分析了传统的模糊聚类方法,基于摄动思想,将传递闭包聚类法与目标函数法相结合,得出了一种既满足聚类效果要求又减小聚类失真的简便算法,同时给出了该聚类方法的步骤.最后通过对水体的水质进行聚类的例子对算法加以应用,显示了算法的可靠性、有效性.     

微扰动法施工紧邻浅埋地铁隧道的钢套管施工技术

通过对沪杭客运专线上跨轨道交通9号线钻孔灌注桩钢套管施工技术的探讨,对钢套管在旋压过程中对周国土体的挤压、自身强度和刚度要求以及对地铁隧道的影响进行了深刻的计算分析,确定了合理的套管旋进深度和壁厚,达到了对盾构隧道微扰动的目的,保证了地铁隧道的安全运营.     

上海轨道交通10号线的土建工程设计思路和新技术应用

针对上海轨道交通10号线土建工程设计的特点和难点,进行新技术应用。通过一体化勘察总体咨询工作前移应对全线地质风险,通过数值模拟提高侧墙连续开孔的综合开发车站抗震能力,通过微扰动技术解决盾构区间穿越机场主跑道等难题,拓展性应用斜交顶管多次进洞实施复杂区域出入口。     

Singularly perturbed solution for nonlinear equations of fourth order with two parameters

A class of singularly perturbed boundary value problem for nonlinear equation of fourth order with two parameters is considered. Under suitable conditions, the existence and asymptotic behavior of solution for boundary value problem are studied using theory of differential inequalities.     

Probability modeling for robustness of multivariate LQG designing based on ship lateral motion

The robustness of LQG designing for latitudinal movement of ship is mainly discussed, when its hydrodynamic parameters fluctuate around criterion value at random on the proportional distributing. When a given ship state at the speed of 18 kn and the course of 45°under Rank 5 state of sea,and the hydrodynamic parameters of the ship fluctuate at random on the proportional distributing with a range of±10%,±20%,±30%,the robustness of multivariate LQG designing for ship is analyzed with applying the probability modeling of relative controlling effect. The result of simulating shows that when the hydrodynamic parameters of ship fluctuates the relative controlling effect of the LQG designing submit to normal distribution and the mean value of relative controlling effect has no remarkable changes comparing to that without perturbation of hydrodynamic parameter.