冰塞下冰块起动分析

对冰塞下冰块临界起动条件进行了分析研究,指出了过去研究的缺陷是与实际情况吻合较差以及计算公式构造不合理有关。根据有关理论分析与推导,提出了冰塞下冰块临界起动计算公式应具有的合理形式。并就部分因子进行了试验研究,研究结果表明,在不考虑ｔｂ／Ｌ和ｎｉ／ｎｂ变化的情况下,冰塞下冰块起动流速和泥沙起动流速的计算公式具有相同的形式。     

Computation of Design Load and Motion for Floating Structures Navigating in Waves

—Analytical and numerical investigation is made of the source potential for floating structurewith forward speed in waves.A particular form is selected for numerical applications,where the double in-tegral of the Green function is transformed into the single one and the oscillation characteristics forintegrands in the specific computation domain are treated numerically.A comparison of calculated exam-p1es with published data is given and it shows that the numerical simulation is satisfactory and the accura-cy is adequate to engineering application.     

Boundary-value problems in the complex world of geodetic measurements

A review of recent progress and current activities towards an improved formulation and solution of geodetic boundary value problems is given. Improvements stimulated and required by the dramatic changes of the real world of geodetic measurements are focused upon. Altimetry–gravimetry problems taking into account various scenarios of non-homogeneous data coverage are discussed in detail. Other problems are related to free geodetic datum parameters, most of all the vertical datum, overdetermination or additional constraints imposed by satellite geodetic observations or models. Some brief remarks are made on pseudo-boundary value problems for geoid determination and on purely gravitational boundary-value problems. Received: 17 March 1999 / Accepted: 19 April 1999     

Modelling of multi-bodies in close proximity under water waves—Fluid forces on floating bodies

This work presents two-dimensional numerical results of the dependence of wave forces of multiple floating bodies in close proximity on the incident wave frequency, gap width, body draft, body breadth and body number based on both viscous fluid and potential flow models. The numerical models were validated by the available experimental data of fluid oscillation in narrow gaps. Numerical investigations show that the large amplitude responses of horizontal and vertical wave forces appear around the fluid resonant frequencies. The convectional potential flow model is observed to un-physically overestimate the magnitudes of wave forces as the fluid resonance takes place. By introducing artificial damping term with appropriate damping coefficients μ∈[0.4, 0.5], the potential flow model may work as well as the viscous fluid model, which agree with the damping coefficients used in our previous work for the predication of wave height under gap resonance. In addition, the numerical results of viscous fluid model suggest that the horizontal wave force is highly dependent on the water level difference between the opposite sides of an individual body and the overall horizontal wave force on the floating system is generally smaller than the summation of wave force on each body.     

黄河水下三角洲前沿深度基准面及潮位变化分析研究

黄河三角洲前沿的陆地由于受地面沉降的影响,使地面高程不断发生变化.在水深测量中,深度基准面是根据陆地水准点高程确定的,陆地水准点高程的变化影响深度基准面的确定,从而影响水深测量的准确性.又由于黄河海港附近有一无潮点,其附近的潮汐性质变化大,在黄河三角洲前沿大范围水深测量中,根据测区潮位变化设立足够的验潮站及统一各个验潮站的水尺零点到同一个深度基准面上,是保证水深测量结果可靠的关键.通过黄河三角洲前沿陆地高程的变化和验潮获得的资料,介绍了黄河三角洲前沿深度基准面的变化和潮位变化情况.     

中国近海海平面变化研究进展

回顾和总结了近年来有关我国近海地区海平面变化的研究进展。综述了海平面变化的原因，海平面资料获取手段的发展，分析研究海平面变化的方法和模型以及海平面上升速率方面的主要成果；简要介绍了海平面均衡基准订正的意义和主要结论；阐述了1985国家高程基准研究工作和成果。     

福建沿岸当地平均海面的高程研究与应用

通过对福建沿岸多年来已有的当地平均海面高程资料和与1985国家高程基准的水准点联测成果,分析并研究了福建沿岸主要验潮站的当地平均海面的高程情况和变化趋势,对福建沿岸当地平均海面的高程（1985国家高程基准）进行了比较深入的研究和探讨,阐述了福建沿岸与浙江、广东沿海平均海面高程的连续性和与我国海区平均海面高程的一致性,论述了当地平均海面高程的应用方法,以解决福建沿海海岸地形图和水深图的基准统一及高度衔接问题。     

一种基于状态空间模型的浮式海上升压站平台动力响应计算方法研究

浮式海上升压站的动力响应分析是其设计阶段的重要内容,对浮式升压站进行结构优化进而改进其水动力性能意义重大。提出一种基于状态空间模型的浮式海上升压站平台动力响应算法,该方法通过频域拟合的方法计算延迟函数频响函数有理分式的系数,得到延迟函数的极值和留数,进而构建延迟函数的状态空间模型,通过状态空间模型代替Cummins方程中的卷积项,从而计算浮式海上升压站的动力响应。采用日本福岛示范项目的浮式升压站模型对方法进行验证,结果表明计算得到的动力响应与商业软件SESAM计算结果吻合较好,说明方法的有效性。     

多模块超大型浮体中连接器刚度对其运动响应的影响

多模块超大型浮体一般由连接器连接,实现海上浮动机场等功能。实际操作中,为约束超大型浮体模块之间的相对运动,连接器通常将承受非常巨大的载荷,给连接器的制造带来巨大的困难。通过对不同环境力情况下不同刚度连接器的研究,分析了连接器刚度对超大型浮体模块之间相对运动与连接器自身承受载荷的影响。研究发现,随着柔性连接器刚度的增加,连接器对超大浮体模块之间相对运动的约束逐渐增强,同时连接器也将承受更大的载荷;此外,较大的连接器刚度,并不利于抵抗模块之间的冲击载荷;最后,连接器刚度的改变会影响其固有振动频率,因此需要尽可能避开共振区域,否则系统容易出现较大的振动,导致模块间相对运动过大,连接器过载。研究结果确定了连接器刚度最佳匹配原则,以指导连接器的工程设计。     

基于全球潮汐模型的东海海域潮汐性质空间分布

利用全球潮汐模型FES 2014(Finite Element Solution 2014)空间分辨率为(1/16)°×(1/16)°的网格点处13个分潮调和常数,借助基于最小二乘法调和分析方法和潮汐特征值的定义算法,定量分析东海海域(117°～131°E,23°～33°N)的潮汐类型、深度基准值和不同潮差类型.结果表...