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1.
This paper quantitatively studies the transient dynamic response of a semi-submersible production platform with the loss of one or several positioning mooring lines.A semi-submersible platform,production risers,and positioning mooring lines are all included in the numerical simulation.Increased motion of the semi-submersible platform,tension variation of the remaining mooring lines/risers and the risk of mooring line or riser clashing are all investigated through fully coupled time-domain analysis.Combined environmental loads are selected from irregular waves and the steady current varying from very rough to extreme sea conditions.Three dimension radiation/diffraction theories and Morison’s equation are applied to calculate first-order wave force and second-order mean drift force of floating semi-submersible platform.Nonlinear time-domain finite element methods are employed to analyze the behavior of mooring lines and risers.Results show that the failure of mooring lines seriously reduce the platform’s stability performance.The tension of the rest lines is also increased accordingly.Remaining lines which are closer to the failed lines will have larger tension increase to compensate.Line-Line distance provides practical information for the risk of clashing investigation. 相似文献
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1区域概况随着气候—海洋系统模拟工作力度的加大,相关古气候改变北大西洋深层水(NADW)生产力速率的论著十分亟需。大多数作者认为整体的NADW生产力在冰期降低,他们的推断范围不完全一致。冰期更大量的南大洋水体涌入北大西洋,而且北大西洋深部对流现在已被更浅的和更南部的对流所取代。有关更新世末次冰期—间冰期旋回NADW演变,主要研究成果如下:(1)沿冰岛—苏格兰溢流水团路径从冰岛盆地采集柱状样,对其进行磁各向异性测试。变化结果同过去20万a水体可变强度相关联。冰期氧同位素2期、4期、6期较之间冰期1期、3期、5期有30%的强度衰… 相似文献
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Empirical orthogonal function(EOF) analysis was applied to a 50-year long time series of monthly mean positions of the Kuroshio path south of Japan from a regional reanalysis. Three leading EOF modes characterize the contributions from three typical paths of the Kuroshio meander: the typical large meander path, the offshore nonlarge meander path, and the nearshore non-large meander path, respectively. Accordingly, the spatial variation characteristics of oceanic anomaly fields can be depicted by... 相似文献
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The tide-induced net advective salt flux in well-mixed estuaries consists of five terms according to the method from Kjerfve.The term resulted from the vertical variation in salinity can be negligible in well-mixed estuaries with four tide-induced salt flux terms,known as F1?F4.To explore the effects of wind on these salt fluxes,the current-salinity analytical model combined with the perturbation analysis is extended by including wind.Analytical expressions for the four salt fluxes are derived separately in the present model.Under the assumption that only the M2 tidal component is accounted for and the salt flux generated by diffusion is not studied,the tide-induced net advective salt flux Qsx is in the seaward direction without the wind effect.By applying the Western Scheldt estuary case,the wind influence on the tidal advection salt flux(TASF)distribution in the F4 term was investigated.The phase difference between zero-order velocity and first-order salinity(Δφ)at the surface layer of the estuary is larger than 90°and smaller than 90°at the bottom layer,which leads to landward TASF in the surface layer and seaward TASF in the bottom layer.The distribution ofΔφis not uniform in the horizontal direction with wind included,which differs from the result without wind.In the case of seaward wind with the speed of 18 m/s,the decrease in the zeroth-order velocity phase(φu)at the surface layer is larger than that of the first-order salinity phase(φs)downstream,which leads to an abnormal seaward TASF in this region.Owing to the surface stress caused by wind,the Stokes compensation flow in the middle and lower reaches increases/decreases with the increase of the landward/seaward wind,while the upstream situation is opposite.Thus,the first-order velocity in the middle and lower reaches increases/decreases with the increase of the landward/seaward wind,while the upstream situation is also opposite.The first-order salinity also increases/decreases with the increase of landward/seaward wind,while the upstream salinity tends to zero.Therefore,the tide-induced net advective salt flux Qsx increases/decreases with the increase of the landward/seaward wind,which is contrary to the usual recognition. 相似文献
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A large sand bar develops in the inner Qiantang River Estuary, China. It is a unique sedimentary system,elongating landwards by about 130 km. Based on long-term series of bathymetric data in each April, July, and November since the 1960 s, this study investigated the morphological behavior of this bar under natural conditions and the influence of a large-scale river narrowing project(LRNP) implemented in the last decades. The results show that three timescales, namely the seasonal, interannual a... 相似文献
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在全世界范围内,哪里有海洋,哪里便有海洋景观;哪里有人类活动,哪里就有海洋文化海洋文化绝不仅仅是西方人的专利,也绝不是黑格尔所说的"中国没有海洋文化"。我们无须说 相似文献
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一、国内外游艇产业发展概况游艇起源于17世纪中叶。当时英皇查尔斯二世登基时,荷兰送给英皇第一艘做工精细的皇家狩猎渔船,这是历史上第一艘游艇。到了18世纪,游艇逐步发展并成为欧洲海洋国家的贵族、富豪夸耀自我,显示地位的一种象征。19世纪以后,螺旋桨、蒸汽机、小功率的马达、自动导航驾驶仪器被先后运用在游艇上。直到20世纪中叶,西方发达国家在第三产业中衍生出游艇俱乐部,在解决了游艇的停泊难题后,使游艇得到了蓬勃的发展。游艇在国际上普遍用于私人消费,与巨大的海船相比,游艇虽然很小,但发展却很快,有巨大的市场。 相似文献
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在回顾海冰监测研究进展及其存在问题的基础上,提出基于卫星遥感资料获取海冰面积的重要性,以第四代可视化计算机语言IDL和MapBasic语言为工具研制并开发了海冰面积信息提取监测系统.整个系统由解译系统和统计分析系统两部分组成.利用1996-2005年渤海NOAA/AVHRR数据和MODIS数据,在该系统的支持下进行了海冰面积信息的提取实例,得到渤海海冰面积解译图和面积数值统计表,结果表明:1996年至2005年,渤海海冰面积(相对最大面积)的变化范围为6 173.34～36 928.00 km2,其中1999年海冰面积最小,2001年海冰面积最大.该系统可为海冰资源的开发利用及海冰监测等工作提供帮助. 相似文献
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For the growth and departure of bubbles from an orifice, a free energy lattice Boltzmann model is adopted to deal with this complex multiphase flow phenomenon. A virtual layer is set at the boundary of the flow domain to deal with the no-slip boundary condition. Effects of the viscosity, surface tension, gas inertial force and buoyancy on the characteristics of bubbles when they grow and departure from an orifice in quiescent liquid are studied. The releasing period and departure diameter of the bubble are influenced by the residual gas at the orifice, and the interaction between bubbles is taken into consideration. The relations between the releasing period or departure diameter and the gravity acceleration show fair agreements with previous numerical and theoretical results. And the influence of the gas outflow velocity on bubble formation is discussed as well. For the bubbles growing in cross-flow field, effects of the cross-flow speed and the gas outflow velocity on the bubble formation are discussed, which is related to the application in ship resistance reduction. And optimal choice of the ship speed and gas outflow velocity is studied. Cases in this paper also prove that this high density ratio LBM model has its flexibility and effectiveness on multiphase flow simulations. 相似文献
10.
Yubin Feng Dong Li Jun Zhao Zhengbing Han Jianming Pan Gaojing Fan Haisheng Zhang Ji Hu Haifeng Zhang Jiaqi Wu Qiuhong Zhu 《海洋学报(英文版)》2022,41(1):99-117
The ecosystem of the sea region adjacent to the Antarctic Peninsula is undergoing remarkable physical and biological changes, in the context of global warming. However, understanding of the dynamics of phytoplankton taxonomic composition in this marginal ice zone remains unclear. In this study, seawater samples collected from 36 stations in the northeastern Antarctic Peninsula were analyzed for nutrients and phytoplankton pigments.Combining with CHEMTAX analysis, remote sensing data, and physico... 相似文献
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黄渤海区捕捞结构的研究 总被引：4，自引：0，他引：4
根据2010年对黄渤海沿海32个主要渔港、渔村和5家网具生产厂家的实地调查和现场测量资料,结合2009年度三省一市(河北、辽宁、山东、天津)的渔具渔法调查报告以及1983~2009年中国渔业年鉴中记载的捕捞产量分类统计资料,对黄渤海区捕捞结构进行了研究.研究结果表明,黄渤海区主要捕捞品种有30种之多,其中年渔获量超过万吨的有14种鱼类、5种甲壳类、4种头足类、2种海蜇和6种贝类.渔业资源品种的多样性决定了黄渤海区捕捞结构的多样化和多层次的特点,现有9大类19型23式130种网型或作业方式,同时受渔业资源变动的影响,捕捞网具也在变化,不断有旧的渔具消失和新的网具出现.其中,拖网是主要作业方式,贡献率为38.47%~51.79%,且近几年还有上升的趋势;其次为刺网,贡献率从1983年最低时的7.66%逐步上升到目前的30.14%;第三为张网,贡献率从1985年最高时的34.31%下降到目前的10.49%;围网和钓具的贡献率一直较低,均不足4%,其他渔具的贡献率为5.98%~13.30%.目前黄渤海区渔业结构的调整方向应当是减少拖网作业,控制刺网总量,限制张网、陷阱类渔具和地笼,鼓励发展钓渔业 相似文献
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渤黄东海潮能通量与潮能耗散 总被引：7，自引：0，他引：7
利用同化高度计资料和沿岸验潮站资料对潮汐数值模式进行同化,根据同化后的数值模式结果,对渤黄东海中的潮能通量和潮能耗散进行了研究.M2分潮从太平洋进入渤黄东海的潮能为122.499GW,占4个主要分潮进入总量的79%.黄海是半日分潮潮能耗散的主要海区.全日分潮则主要耗散在东海.全日分潮在遇到陆坡的阻挡以后有一部分潮能沿着冲绳海槽向西南传播,并有一部分潮能反射回太平洋,其中O1分潮通过C3断面反射回太平洋的潮能,约占其传入东海潮能的44%. 相似文献
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黄、渤海是我国重要的海洋经济渔业开发区域,海水中痕量金属的含量及其存在形态会对海洋环境、海洋渔业产生重要影响。随着近年我国痕量金属采集与分析测试技术的发展,数据的准确性有了新的提升。2016-06—07采集黄、渤海40个站位的海水样品,测定其溶解态金属Cd的总浓度,并应用电化学方法(阳极溶出伏安法)分析Cd存在形态。结果表明,渤海海水中的总溶解态Cd浓度是南黄海海水中的2~3倍,这可能与渤海海水停留时间较长,水深较浅,周边较多河流输入有关。20%~92%以上的溶解态Cd是以有机络合物形态存在,以自由离子态存在的Cd浓度不超过100 pmol/L,低于Cd对浮游生物的毒性阈值。渤海比黄海的金属配体浓度高出2倍以上,高值出现在黄河口周围海域,表明黄河水携带较多有机配体输入。推测我国近海有机配体来源可能包括陆源输入、沉积物再悬浮的解析过程以及藻类分泌。研究还表明,黄、渤海海水中溶解态Cd的有机配体络合常数较其他海域的稍高,这与我国近海废、污水排放的有机络合配体类型有关。 相似文献
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日本海、鄂霍次克海和白令海的古海洋学研究进展 总被引：2，自引：0，他引：2
边缘海的存在使大陆和大洋之间的物质和能量交换变得相当复杂。在构造运动和海平面升降的控制下,边缘海和大洋之间时而连通时而隔绝,各种古气候变化信号都在一定程度上被放大。基于近期有关西北太平洋边缘海的古海洋学研究成果,简要概述了日本海、鄂霍次克海、白令海以及北太平洋地区自中新世以来的古气候和古海洋环境演化特征,并认为它们与全球其它地区一样也受控于因地球轨道参数变化引起的太阳辐射率的变化,大尺度的气候变化具有与地球轨道偏心率周期相对应的100ka周期,而41ka的小尺度周期则受地球自转轴斜率变化的控制。一些突发性的气候变化则是由气候不稳定性、海峡的关闭与开启和其它一些地球气候系统的非线性活动所驱动。但同时作为中高纬度边缘海,它们的古海平面、古海水温度、古洋流等古海洋环境因子的变化特征还受到冰盖扩张和退缩、构造运动、冰川性地壳均衡补偿、东亚季风等因素的影响,具有一定的区域特点。 相似文献
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利用"908"专项所获取的CTD观测资料,系统地阐述了渤、黄、东海温度的分布特征及季节变化。结果显示,冬季,水平方向上,水温分布呈现多舌状:外海温度多暖舌结构,近岸等温线基本平行于岸线,并出现多个指向南方的冷水舌,且暖流区与近岸冷水区间形成了较强的温度峰。夏季,三大海域底层均出现了各具特色的冷水团和冷水块,最为典型的有"渤中冷水"、"辽东湾冷水"、黄海冷水团、青岛冷水团和东海北部底层冷水。春、秋季水温分布呈现过渡季节的特征。春季,跃层开始出现,"渤中冷水"及黄海冷水团等冷水现象开始形成。进入秋季,跃层明显下沉,直至消失,水温分布逐渐呈现垂向均匀状况。同时,分析还表明,三大海域的水温分布存在明显的区域性差异。水温分布的年变幅从北向南、从近岸向外海递减。 相似文献
18.
东、黄海沉积物-水界面营养盐交换速率的研究 总被引：9，自引：0，他引：9
2000年10月和2001年5月随“东方红2号”考察船在东、黄海进行考察,在A2、E2、E4、E5、E65个站位作了培养实验,研究沉积物-水界面在氧化和还原条件下的交换通量。在东海海域,NO3-、PO43-、总磷(TDP)由水向沉积物中扩散,NH4 、SiO32-由沉积物向水中扩散,NO3-、TDP、NH4 在还原条件下的交换通量大于氧化条件下的交换通量,PO43-、SiO32-在氧化还原条件下的交换通量基本一致。在黄海海域,两站位各溶解态营养盐的迁移方向有较大差异。在距离陆地较近的海域,各溶解态营养盐多由水中向沉积物中扩散,且距离陆地越近,交换通量越大。在东、黄海海域,沉积物释放的SiO32-对初级生产力的贡献分别为13%、10%~18%,与河流输送和大气沉降相比,沉积物对黄海、东海SiO32-的贡献分别占90%、86%,说明沉积物是SiO32-的源。而在整个东、黄海海域,对于溶解无机氮(DIN)和PO43-来说,它们的交换通量为负值,即沉积物从水体中吸附溶解无机氮和磷,说明沉积物是DIN和PO43-的汇。 相似文献
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针对渤海及附近海区的曲折岸线变化以及水文资料时空分布不均匀性的特点,使用四维客观分析LOESS方法得到逐月气候态盐度场。结果表明:渤海南部沿岸水扩展和运移受季风影响显著。冬季沿岸水向渤海湾和莱州湾堆积,形成沿山东半岛龙口海岸东向爬行的水舌,该水舌在蓬莱水域向东扩展;夏季沿岸水向渤海中部冲溢,特别是在黄河口附近,其核心区厚度可达8 m,可扩展到119°30′E处,同时莱州湾内的沿岸水向湾内西部收缩。冬季渤海海峡呈现显著"北进南出"水交换态势;夏季渤海海峡定常流方式的水交换特征不明显。 相似文献
20.
Seasonal variation of the water circulations in the East China Sea and the Yellow Sea is investigated with use of a robust diagnostic numerical model. Water circulations in four season are calculated diagnostically from the observed water temperature and salinity data from JODC (Japan Oceanographic Data Center) and wind data from COADS (Comprehensive Ocean-Atmosphere Data Set). Counter-clockwise circulations are developed at the upper and middle layers and a clockwise one at the lower layer in the central part of he Yellow Sea in summer. On the other hand, a clockwise circualtion is developed from the surface to the bottom in the Yellow Sea and a counter-clockwise one in, the northern part of the East China Sea in winter. 相似文献