Dynamic Responses of Mobile Offshore Base Connectors

A Mobile Offshore Base (MOB) is a multi-purpose logistics base, which can be stationed in coastal or international waters. In the conceptual design of the MOB, attention should be paid to the dynamic responses of the inter-module connectors because tremendous loads occur in the connectors. In this paper, a study on dynamic responses of the MOB connectors is carried out by use of the Rigid Module Flexible Connector (RMFC) model which assumes that the module stiffness is significantly larger than that of the connector. In the analysis, the connector is modeled as a linear spring, which restricts relative translations but allows for relative rotations of modules. The 3-D source distribution method is adopted to determine the hydrodynamic forces of the modules, and the hydrodynamic interaction between modules is taken into account. The module motions and connector loads for 12 connector stiffness cases in regular and irregular waves are calculated with the multi-rigid-body motion equations. And the calculat     

Mass Transport in a Thin Layer of Bi-Viscous Mud Under Surface Waves

The mass transport in a thin layer of non-Newtonian bed mud under surface waves is examined with a two-fluid Stokes boundary layer model. The mud is assumed to be a bi-viscous fluid, which tends to resist motion for small-applied stresses, but flows readily when the yield stress is exceeded. Asymptotic expansions suitable for shallow lluid layers are applied, and the second-order solutions for the mass transport induced by surface progressive waves are obtained numeri-cally. It is found that the stronger the non-Newtonian behavior of the mud, the more pronounced intermittency of the flow. Consequently, the mass transport velocity is diminished in magnitude, and can even become negative (i. e. , oppo-site to wave propagation) for a certain range of yield stress.     

Numerical Simulation of Wave Scour Around A Large-Scale Circular Cylinder

A numerical model is developed for estimation of local scour around a large circular cylinder under vvave action. The model includes wave diffraction around structures, bed shear stress calculation inside the vvave boundary layer and topo-graphical change model. The vvave model is based on the improved Boussinesq equations for varying depth. The vvave boundary layer is calculaled by solving the integrated momentum equation over the boundary layer. The bed shear stress due to streaming, an important factor affecting the sediment transport around a large-scale cylinder, is calculated. The Lagrangian drift velocity is included in calculation of the suspended sediment transport rates. The model is implemented by a finite element method and the results from the present model, which agree well with experimental data, are com-pared vvith those from other methods.     

Investigation of Motion of Two Hinged Bodies Moored by Mooring Lines in Waves

In this paper, the motions are studied of a multi-body which is composed of two plates hinged together and moored by eight mooring lines in regular waves. The experimental results are compared with computational results. The linear po-tential theory and the perturbation method are combined to study this complicated system. The former is used to calculate the wave forces acting on the plates and the motion responses of them, while the latter is used to describe the dynamic character of the eight mooring lines coupled with the two hinged plates. Some response results of each plate are presented and comparisons between calculated results and experimental data are given. All the calculations are confined to regular beam waves.     

一次中亚低涡造成的天山北坡暴雨GPS大气水汽总量演变特征

2015年6月26—28日中亚低涡造成天山北坡出现暴雨天气,本文利用常规观测、NCEP再分析资料及9站地基GPS遥感的大气水汽总量资料(GPS-PWV)对这次天气过程水汽特征进行深入研究,结果表明:(1)降水前,500 hPa阿拉伯海水汽经青藏高原向中亚低涡输送,低涡增湿明显;降水期间,500 hPa低涡向北移动并减弱成槽东移,700 hPa孟加拉湾经四川盆地、河西走廊的偏东水汽输送通道建立,与低涡自身偏南(东南)气流在暴雨区上空汇合,暴雨区中低层增湿剧烈;(2)深厚低涡造成的强降水前测站GPS-PWV均存在1~3 d增湿过程和1~2次跃变过程,强降水发生前GPS-PWV跃变均超过5 mm·(4 h)~(-1);(3)在同样水汽输送、辐合条件下,干旱区测站GPS-PWV急剧增幅越大,地面雨强越强,在一定程度上,水汽输送和水汽的辐合与GPS的剧增存在一定的对应关系;(4)中亚低涡造成的乌鲁木齐强降水发生前4~5 h的GPS-PWV增幅达到4 mm以上,GPS-PWV峰值往往达到气候平均值2倍左右。     

图片新闻

11月21日,国土资源部举办第三场学习党的十九大精神宣讲报告会,邀请中央纪委宣传部部长朱国贤就十八届中央纪委向党的十九大的工作报告精神进行宣讲。国土资源部部长、国家土地总督察姜大明主持报告会并讲话。报告会以视频会议形式举行。部领导、总规划师,中国地质调查局、国家土地督察北京局及部其他直属单位主要负责同志,部离退休党支部书记,部机关全体干部在主会场参加。国家海洋局、国家测绘地理信息局、中国地质调查局及其所属单位、各派驻地方的国家土地督察局、部其他直属单位干部职工在各分会场参加。     

沿海海—气界面的化学物质交换

沿海海－气界面化学物质的交换对生物地球化学循环起着十分重要的作用。大气沉降过程是化学物质进入沿海区域的重要途径之一。物质平衡估算的结果指出，在某些沿海区域，经由大气输入的若干痕量物质的总量几乎相当于河流的输入量，有的甚至更多。大气沉降作用是一些沿海区域氮化物的重要来源，并与富营养化有紧密关系。     

Transgressions of Late Cretaceous to Early Tertiary in Eastern China

ＴＲＡＮＳＧＲＥＳＳＩＯＮＳＯＦＬＡＴＥＣＲＥＴＡＣＥＯＵＳＴＯＥＡＲＬＹＴＥＲＴＩＡＲＹＩＮＥＡＳＴＥＲＮＣＨＩＮＡＱｉｕＳｏｎｇｙｕ，ＬｕＢｉｎｇｌｉ，ＣｈｅｎＹｏｎｇｃｈｅｎｇ（ＪｉｌｉｎＨｅａｄｑｕａｒｔｅｒｓＯｆＰｅｔｒｏｌｅｕｍＰｒｏｓｐ...     

全国中文核心期刊名录(自然科学)

由北京大学图书馆和北京高校图书馆期刊工作研究会共同主持、全国216位学科鉴定专家和148位专业人员参加的国家教委人文社会科学研究“九五”规划项目“核心期刊的文献计量学研究”子课题——“中文核心期刊的文献计量学研究”，经过两年多的工作于2000年顺利完成。该研究成果最新认定了1　571种全国中文核心期刊。《黄渤海海洋》学报继1996年之后，在2000年再次被认定为中文核心期刊。 　　现将《中文核心期刊要目总览》(2000年版［第三版］)认定的自然科学全部265种中文核心期刊刊名介绍如下。     

Second sea－entering approach of Changjiang River： Tongl Canal－planning of control dimensions， analysis of erosion and siltation and selection of outlet

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