Modelling of flow around a near-bed pipeline with a spoiler

Flow around a pipeline with and without a spoiler near a smooth wall is simulated by solving the Navier–Stokes equations. Finite-difference formulation with a second-order upwind scheme in a curvilinear coordinate system is employed. The influences of the spoiler on hydrodynamic forces, pressure distribution, vortex shedding frequency, velocity profile under the pipe, as well as shear stress on the wall are investigated. The attachment of a spoiler significantly increases drag, root-mean-square (RMS) lift, flow through the gap between the pipe and the wall and shear stress on the seabed around the pipe. The spoiler also generates a non-zero mean downward force on the pipeline, which may enhance the self-burial of the pipeline.     

Numerical simulation of solitary wave scattering by a circular cylinder array

The interaction of a solitary wave with an array of surface-piercing vertical circular cylinders is investigated numerically. The wave motion is modeled by a set of generalized Boussinesq equations. The governing equations are discretized using a finite element method. The numerical model is validated against the experimental data of solitary wave reflection from a vertical wall and solitary wave scattering by a vertical circular cylinder respectively. The predicted wave surface elevation and the wave forces on the cylinder agree well with the experimental data. The numerical model is then employed to study solitary wave scattering by arrays of two circular cylinders and four circular cylinders respectively. The effect of wave direction on the wave forces and the wave runup on the cylinders is quantified.     

九龙江河口区表层水铀同位素的粒级分布

利用微滤和超滤技术研究了九龙江河口区表层水中铀及其同位素组成的粒级分布和地球化学行为.结果表明,溶解态(<0.4μm)中低分子量组分(<10 000 u)占主要份额,胶体态(10 000 u~0.4μm)238U所占比例不足1%,且随盐度的增加其所占份额逐渐降低.溶解态、低分子量组分和胶体态238U的比活度与盐度之间存在良好的线性正相关关系,证实它们在九龙江河口区呈现保守行为.在颗粒态(>0.4μm)中,各粒级组分238U所占份额主要受控于相应颗粒物的浓度,在盐度小于20的区域,各粒级颗粒组分238U占颗粒态的份额有如下变化次序:10~53μm>2~10μm>0.4~2μm>大于53μm,而在盐度大于30的近外海站位,该次序发生一些变化:0.4~2μm>10~53μm>2~10μm>大于53μm,最小粒级颗粒组分238U的贡献有所增加,反映了自生铀贡献的加强.九龙江河口区表层水中溶解态(包括低分子量组分和胶体态)的234U/238U)_A.R.均大于1,显示出234U过剩的特征,而各粒级颗粒组分中的234U/238U)_A.R.则接近于平衡值(1.0).这一现象与陆地岩石风化过程中水体对铀的淋滤释出量及234U的优先浸出有关.对232Th/238U质量比的研究显示,溶解态及其所包括的低分子量组分和胶体态的232Th/238U质量比均小于1,而颗粒态及其所包括的4个粒级组分中的232Th/238U质量比均大于1,反映了向外海输送过程中铀、钍地球化学行为的差异.     

近岸溢油漂移扩散预测方法研究——以胶州湾溢油事件为例

近些年,由于中国经济的高速发展,原油需求逐年增长,同时海上溢油事故发生的风险也在加剧。海上溢油会严重破坏海洋环境,危害我国经济发展,加强溢油漂移扩散预报研究能够为海上溢油应急响应提供技术支撑。因此,国家海洋信息中心研发了海上突发事件应急一体化预测预警系统。该系统基于GIS平台研发,能够在二维电子海图基础上叠加相关的海洋环境动力要素信息,模拟溢油扩散和漂移态势,同时计算剩余油量,估算溢油面积以及岸线吸附程度等。2013年11月22日,山东黄岛发生输油管道爆炸事故,造成大量原油溢入胶州湾。本文利用该系统结合高分辨率大气模型WRF的三重嵌套技术和海流模型SELFE的非结构化网格加密技术,对事故溢油漂移扩散开展了预测工作。预测结果显示,油污受胶州湾内往复流的影响极大,72 h后,胶州湾内外大部分海域都将存在油污,主要集中在黄岛沿岸海域、团岛及浮山湾附近,预测扫海面积为70.32 km2。经海事部门高分辨率卫星观测结果印证,系统模拟的溢油分布较为合理。该系统的业务化应用为相关海上溢油污染应急工作提供了一定理论依据和参考。     

Comparison of Strain-rate Dependent Stress-Strain Behavior from Ko-consolidated Compression and Extension Tests on Natural Hong Kong Marine Deposits

This article presents results from a series of K_o-consolidated compression and extension triaxial tests on specimens from undisturbed samples of Hong Kong Marine Deposits (HKMD). To investigate the strain-rate effects, a total of seven K_o-consolidated triaxial tests were conducted including four compression tests and three extension tests. After K_o-consolidation, the triaxial test specimens were sheared at step-changed axial strain rates under three different confining pressures of 50 kPa, 150 kPa, and 400 kPa, respectively. The step-changed strain rates were applied in the following order: +2%/h, +0.2%/h, +20%/h, -2%/h (unloading) and +2%/h (reloading) for the four compression tests and -2%/h, -0.2%/h, -20%/h, +2%/h (unloading) and -2%/h (reloading) for the three extension tests. The results are reported and analyzed in the paper. The results show that the strain rate effects, the stress-strain characteristics, and the effective stress paths of the specimens for tests in a compression state are different from those for tests in an extension stage. One order of magnitude increase in axial strain rate causes an average 8.6% increase in undrained shear strength for compression tests and a 12.1% increase for extension tests. It is also found that the failure mode of the specimens in compression is different from that in extension. The stress-strain behavior of specimens shows strain-softening and a clear shear band in compression tests, but strain-hardening without any clear shear band in extension tests for the same absolute value of axial strain.     

皱纹盘鲍对氯霉素的通透性吸收与扩散

在海水溶液中的氯霉素分子可以越过皱纹盘鲍Ｈａｌｉｏｔｉｓ ｄｉｓｃｕｓ ｈａｎｎａｉ Ｉｎｏ的体表结构进入其血淋巴液中。鲍血淋巴液中氯霉素的浓度与药浴液的氯霉素浓度，温度均呈线性关系，药浴时间的效应表现的Ｓ形逼近曲线。在２０℃的海水中，鲍血淋巴液中的氯霉素向体外扩散的半衰期为４２ｍｉｎ。     

水槽造流系统水力计算与泵机选择

提供一种完整的用于试验水槽造流系统的水力计算和泵机选择方法 ,可用于其他类似工程设计。     

Geochemistry of trace elements and Sr-Nd isotopes of foraminifera shell from the Okinawa Trough

ＩＮＴＲＯＤＵＣＴＩＯＮＰｒｏｖｅｎａｎｃｅｏｆｍａｒｉｎｅｓｅｄｉｍｅｎｔｓｈａｓａｌｗａｙｓｂｅｅｎａｆｏｃｕｓｅｄｐｒｏｂｌｅｍｉｎｍａｒｉｎｅｓｅｄｉｍｅｎｔｇｅ ｏｌｏｇｙ.Ｒｅｃｏｇｎｉｔｉｏｎｏｆｅｎｄｍｅｍｂｅｒｓａｎｄｅｓｔｉｍａｔｉｏｎｏｆｔｈｅｉｒｒｅｌａｔｉｖｅｐｒｏｐｏｒｔｉｏｎｓｆｒｏｍｍｉｘｅｄｓｅｄｉｍｅｎｔｓｈａｖｅｂｅｅｎａｋｅｙｃｏｎｔｅｎｔｉｎｔｈｅｓｔｕｄｙｏｆｐｒｏｖｅｎａｎｃｅ .Ｆｏｒｔｈｉｓａｉｍ ,ｉｔｉｓｎｅｃｅｓｓａｒｙｔｏｓｅｌｅｃｔｅｎｄｍｅ…     

Analytic Solution of Interaction Between Surface Waves and Floating Elastic Plates with Elastic End-Restraints

Based on the dynamic theories of water waves and Mindlin plates,the analytic solution of interaction between surface waves and two-dimensional floating elastic plates with edge-restraint is constructed by use of the Wiener-Hopf technique.Firstly,without regard for elastic edge restraint,the wave-induced responses of elastic floating plate analyzed by the present method are in good agreement with the results from literature and experimental results.Therefore,it can be shown that the present method is valid.Secondly,three end-restraint cases(i.e.,the left-end elastic restraints,the both-end elastic restraints,and the right-end elastic restraints)are proposed to reduce the vibration of floating plates,in which the spring is used to connect the sea bottom and the floating plate's left(or right)edge.The relations between the spring stiffness and the parameters of wave-induced responses of floating plates are discussed.Moreover,the effective method to reduce the vibration of floating elastic plates can be obtained through comparison.     

卤虫的发育与蜕皮

我国北方孤雌生殖卤虫在盐度为60,水温为19—28℃的条件下,自卵内孵出无节幼虫长成至性成熟产仔(无节幼虫或卵),需经蜕皮12—15次,其中多数为14次,历时15—18天,随后每次产仔即行蜕皮一次,本文描述了卤虫各个不同令期发育的外部形态变化,并根据其蜕皮次数和形态特征,将卤虫的发育分为十五令(15th instar)。此外还观察到在孤雌生殖的卵中有发育成为雄性的个体。