Numerical simulation of the hydrodynamic behaviour of submerged plane nets in current     

Yu-Cheng Li  Yun-Peng Zhao  Fu-Kun Gui  Bin Teng 《Ocean Engineering》2006,33(17-18):2352-2368

The aim of this paper is to investigate the shape and tension distribution of fishing nets in current. A numerical model is developed, based on lumped mass method to simplify the net. The motion equation is set up for each lumped mass. The Runge–Kutta–Verner fifth-order and sixth-order method is used to solve these simultaneous equations, and then the displacement and tension of each lumped mass are obtained. In order to verify the validity of the numerical method, model tests have been carried out. The results by the numerical simulation agree well with the experimental data.  相似文献   

泉州湾围海工程对海洋环境的影响   总被引：17，自引：3，他引：17  

陈彬  王金坑  张玉生  唐森铭  林景宏  郑凤武  张继伟 《台湾海峡》2004,23(2):192-198

采用现场调查资料与历史资料对比的方法,从海岸和海底地貌、水环境质量、海洋生物种类和群落结构等几方面分析了近几十年来福建泉州湾围海工程的环境效应.结果表明,围海工程促进了海滩的淤浅,减小了内湾的纳潮量和环境容量,使得泉州湾内湾水质恶化;其最终后果为围海工程附近海区生物种类多样性普遍降低,优势种和群落结构发生改变.  相似文献   

Analysis of Dynamic Characteristics of Submarine Free Spanning Pipelines by Complex Damping Method   总被引：2，自引：0，他引：2  

傅强郭海燕  杨新华 《中国海洋工程》2004,18(3):485-491

Considering the effect of the internal flowing fluid and the external marine environmental condition, the differential equation for the vortex-induced vibration (V1V) of the free spanning pipeline is derived and is discretized by the Hermit interpolation function. The free vibration equation with the damping term is solved by the complex damping method for the natural frequency, and then the effect of fluid damping on the natural frequency of the free spanning pipeline is analyzed.The results show that fluid damping has a significant influence on the damped natural frequency of the free spanning pipeline in the lock-in state, while it has little influence when the pipeline is out of the lock-in state. In the meantime,the change of the free span length has the same effect on the damped natural frequency and the undamped natural frequency.  相似文献   

蒸发波导环境下风浪对电磁波传播影响的数值模拟研究     

闫西荡  杨坤德 《海洋与湖沼》2020,51(1):13-19

蒸发波导是一种特殊的大气波导,在其中传播的电磁波信号会被陷获在近海大气层中,实现超视距传播。受海表面温度、湿度、风速、微波频率等因素的影响,海洋蒸发波导环境中的微波传播特性起伏变化很大,规律十分复杂。以往的工作主要通过计算这些气象因素对蒸发波导条件下大气折射率剖面的影响来分析它们对路径损失的作用,其结果与实验数据仍有较大差异。本文在一定的蒸发波导条件下,利用一维分形海面模型产生海面“地形”,将其作为抛物方程电磁波传播模型的边界条件进行计算,得到相应的路径损失,并与传统计算方法进行对比,分析了不同蒸发波导高度、不同频率及不同接收天线高度时的数值模拟情况,可为舰艇通信系统或者雷达系统的设计提供相应的依据。  相似文献   

Pb²⁺对青蛤的急性毒性及对其血淋巴液中免疫相关酶活性的影响     

王瑞  黄雨辰  熊德东  黄亚  田甜  孟彬  梁健 《海洋科学》2020,44(3):59-65

采用静态急性毒性实验研究了重金属Pb~(2+)对青蛤(Cyclina sinensis)的生物急性毒性效应,测定了在96 h Pb~(2+)半致死浓度的1/10(TC组)和1/100(SC组)两个浓度胁迫下,血淋巴液中酸性磷酸酶(ACP)、碱性磷酸酶(AKP)和溶菌酶(LSZ)活性的变化。结果显示:Pb~(2+)的96 h LC50为7.938 mg/L; SC组ACP活性表现为诱导-抑制趋势,除4 d外均与对照组差异显著(P0.05), TC组为抑制趋势,为3个组中的最低,与对照组差异显著(P0.05);实验组SC组和TC组的AKP、LSZ活性均表现为前期为诱导中后期受抑制的趋势,与对照组差异显著(P0.05),且TC组活性始终低于SC组,表现出Pb~(2+)的胁迫浓度越高酶活性受到的抑制作用越大。以上结果表明,重金属Pb~(2+)对青蛤的毒性级别为高毒级,能造成青蛤免疫相关酶的活性受到抑制,影响青蛤的免疫能力,而且这种抑制作用随着环境中Pb~(2+)浓度增加而增加。  相似文献   

黄海、渤海底层温度数值预报方法的研究     

王宗山  徐伯昌  龚滨  邹娥梅  李繁华 《海洋科学进展》1996,(3)

根据文献［ｌ］建立的底层温度（ＴＨ）与其水柱垂向平均温度（）的经验关系，结合流体动力学方程和（垂向平均）热传导方程，发展了以水气温差和风速为已知量的底层温度二维数值预报模式。该模式避开了海面热量和动量输入在垂直水柱中分配的复杂物理过程而直接报出底层水温场，具有较好的实用性；此外，从试报结果看，效果令人满意。  相似文献   

A NUMERICAL MODEL FOR THE TIDES AND TIDAL CURRENTS IN THE TAIWAN STRAIT     

方国洪  杨景飞  赵绪才 《海洋学报(英文版)》1985,4(2):189-200

Semidiurnal and diurnal tidal waves in the Taiwan Strait are computed simultaneously by using finite difference method with two-dimensional nonlinear hydrodynamic equations. The agreement between the computed and observed results is considered satisfactory.  相似文献   

Sediment Transport in Rivers and Coastal Waters     

YANG  Shu-qing 《中国海洋工程》2003,17(4):527-540

Following Bagnold's approach, a relationship between sediment transport and energy dissipation is developed. The major assumption made in the study is that the near bed velocity plays a dominant role in the process of sediment transport. A general relationship between energy dissipation and sediment transport is first proposed. Then the equations for total sediment transport are derived by introducing the appropriate expression of energy dissipation rate under different conditions, such as open channel flows, combination of wave and current, as well as longshore sediment transport. Within the flows investigated, the derived relationships are fairly consistent with the available data over a wide range of conditions.  相似文献   

黄河水中胱氨酸对铅(Ⅱ)与悬浮粒子相互作用的影响   总被引：1，自引：0，他引：1  

杨宏伟  焦小宝  郭博书  樊海燕  郝向英 《海洋湖沼通报》2000,(2):1-5

研究了黄河水中胱氨酸对铅(Ⅱ)与悬浮粒子相互作用的离子交换率E(%)-pH关系曲线的影响.结果表明:(1)2.0 u mol·L-1 的胱氨酸降低了离子交换率E(%);(2)与未加有机物相比"S型曲线"左移0.95个pH单位;(3)随着胱氨酸浓度的增加,离子交换率提高.  相似文献   

沉积物粒度参数的无偏估计及其在长乐海岸的应用   总被引：1，自引：0，他引：1  

杨锐  雷怀彦  刘建辉  官宝聪  黄磊  林炳煌 《海洋地质前沿》2007,23(10):33-36

根据数理统计方法对粒度参数进行无偏估计,使之较以往参数估计更符合无系统误差的这一估计量的评选标准,并用这一方法对长乐东部海岸的风沙进行了系统的粒度参数分析,结果表明长乐海岸风沙沉积物的主要粒级为细沙,分选好,偏度为近对称,峰态很窄等特征,说明研究区域海岸风沙的搬运风动力主要为NE向、而且动力强度较稳定。  相似文献