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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
2.
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
3.
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
4.
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
5.
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
6.
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
7.
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
8.
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
9.
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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12.
《Marine Policy》2015
Marine renewable energy (MRE), though a relative newcomer to the ocean and coastal commons, has become a significant driver of marine spatial planning in the US, posing particular challenges to commercial fisheries and fishing communities. State and federal agencies with primary oversight for MRE development have focused on the identification of places where MRE might proceed unhindered by other uses, most notably coastal fisheries. These agencies and MRE developers have focused on potential space-use conflict and standard mitigation measures for loss of access to that space. However, discussions with fishery participants and other community members, as well as observations of processes on the US West and East Coasts, reveal a complex, multi-faceted social–ecological system not easily parsed out among users, nor amenable to classic mitigation formulas. Recent ethnographic research on potential space-use conflicts and mitigation for MRE demonstrates that marine space use is dynamic and multi-dimensional, with important linkages among fisheries, communities and other interests. Although experiences vary within and across regions and fishing communities, this research illustrates the weak position of fishing communities in marine spatial planning in the context of MRE development. This paper considers the implications of MRE for US East and West Coast fisheries and fishing communities situated within the larger context of neoliberalism and commodification of the ocean commons. 相似文献
13.
海洋能具有储量巨大、绿色清洁等特点,是全球应对气候变暖、调整能源结构的重要选择之一,欧、美等发达海洋国家非常重视发展海洋能,将其作为战略性资源进行技术储备。我国海洋能资源既有着总量丰富、种类齐全、区域性强等优势,也存在密度较低的劣势。在财政部、科技部、国家海洋局等的大力支持下,我国海洋能利用技术取得了明显进步,潮流能和波浪能等代表性技术和装置经历了长期海试,为稳定示范应用奠定了坚实的基础。在建设海洋强国、实施国家能源战略、发展战略性新兴产业、推进生态文明建设、21世纪海上丝绸之路的背景下,随着我国海洋能核心关键技术的不断突破,海洋能装备制造及运行维护必将成长为对经济社会长远发展具有重大引领带动作用的战略性新兴产业。 相似文献
14.
《Marine Policy》2015
When the development of marine renewable energy (MRE) is only possible inside already established marine protected areas (MPAs), and there is a risk of ecosystem loss, environmental or monetary compensation -being the last step in a hierarchy of mitigation measures- might be an option for working out a trade-off between energy production and nature protection. In this article, it is argued that for this type of siting situation, instead of the well-established strategy of no net loss, a net gain should be provided from the MRE developer to the MPA manager, which acts as an incentive for the manager to cooperate and covers future potentially lost conservation benefits due to MRE potential damages. Based on this argument, a hypothetical example is used to demonstrate that a net gain is ensured only when there is a societal surplus from a combined MRE-MPA arrangement that can be divided between the players through bargaining. However, when asymmetric information is involved, it is shown that cooperative solution concepts are more sufficient for leaving both players better off after coexistence than before. 相似文献
15.
《Marine Policy》2015
The world׳s oceans are currently undergoing an unprecedented period of industrialisation, made possible by advances in technology and driven by our growing need for food, energy and resources. This is placing the oceans are under intense pressure, and the ability of existing marine governance frameworks to sustainably manage the marine environment is increasingly being called into question. Emerging industries are challenging all aspects of these frameworks, raising questions regarding ownership and rights of the sea and its resources, management of environmental impacts, and management of ocean space. This paper uses the emerging marine renewable energy (MRE) industry, particularly in the United Kingdom (UK), as a case study to introduce and explore some of the key challenges. The paper concludes that the challenges are likely to be extensive and argues for development of a comprehensive legal research agenda to advance both MRE technologies and marine governance frameworks. 相似文献
16.
We investigate the phantom dark energy model derived from the scalar field with a negative kinetic term. By assuming a particular relation between the time derivative of the phantom field and the Hubble function, an exact solution of the model is constructed. Absence of the `big rip' singularity is shown explicitly. We then derive special features of phantom dark energy model and show that its predictions are consistent with all astrophysical observations. 相似文献
17.
GF-1 WFV图像经验模分解的光谱保真性与水深遥感探测 总被引：1，自引：2，他引：1
水深是海洋环境的重要参数之一，水深遥感反演是水深测量的一种重要手段。经验模分解（EMD）具有剔除小尺度波浪信息，留下大尺度水下地形信息的特性。本文利用EMD对高分一号卫星宽幅影像进行尺度变换，使用光谱相关系数、光谱角、光谱偏差和光谱相对偏差等评价指标，对剩余层图像进行光谱保真性分析；利用改进的对数转换比值模型对原始影像和剩余层图像进行水深反演，并进行相关性分析与精度评价。研究结果表明:（1）评价指标显示EMD变换后影像具有相当的保真性；空间断面分析表明EMD去除了小尺度的噪声信息，保留了水下地形变化信息。（2）经均匀分布的检查点验证，两区域的原图像反演水深和实测水深的相关性较好，相关系数达0.75以上，且两种波段组合的MAE和MRE均不超过2.42 m和8.5%。（3）对EMD的全部10层进行水深反演，蓝绿波段的MAE和MRE均不高于1.62 m和5.8%；绿红波段的MAE和MRE均不高于1.93 m和6.9%。（4）对于不同的波段组合，蓝绿波段组合在各剩余层的水深反演效果明显优于绿红波段，经EMD后的水深反演效果明显提高。（5）20~30 m水深段的反演精度整体要高于30~40 m，该模型应用于较浅水深段更具优势。 相似文献
18.
Remote sensing bathymetry inversion can quickly obtain water depth data of large areas, but this process relies on a large number of in-situ depth data points. USV-based (Unmanned Surface Vehicle) technique can obtain the bathymetry data of shallow water where ordinary ships are inaccessible, but this technique is inefficient and generally only data along survey line can be collected. The combination of USV and high-resolution remote sensing provides a new solution for water depth surveying and mapping around an island. This paper focuses on the key techniques, using USV sounding data and GeoEye-1 multispectral remote sensing images covering the region of Wuzhizhou island in the experiment. The results show that the MAE (Mean Absolute Error) of USV sounding is 0.25 m, while the MRE (Mean Relative Error) is 1.41%, and the MRE of remote sensing bathymetry aided by USV sounding can be controlled within 20%. Errors are mainly from areas shallower than 5 m, and are also affected by the USV sounding position accuracy. It shows that it is feasible to combine the USV sounding and high-resolution remote sensing bathymetry, and this technique has broad application prospects in the field of bathymetry in large shallow areas. 相似文献
19.
我国港口企业发展现代物流探讨 总被引：1，自引：0，他引：1
现代物流是现阶段港口企业在结构调整中的一个主流发展方向,从港口在当前状况下发展现代物流的战略意义、我国港口企业推动现代物流发展的优势、港口企业发展现代物流所采取的具体形式3个方面,对我国港口发展现代物流的重要性和策略进行了论述． 相似文献
20.
大气校正是水体定量遥感的基础与前提。本文从大气校正模型、大气校正模型参数、水体组分差异以及水深反演波段组合方式4个维度探讨大气校正模型对水深反演的影响。研究采用6S、FLAASH、ACOLITE与QUAC 4种大气校正模型,选取大陆型、海洋型与城市型气溶胶模式,以瓦胡岛西北侧与谢米亚岛周边浅水作为清洁水体研究区,以辽东浅滩与槟城海峡作为浑浊水体研究区,基于Landsat-8多光谱影像开展大气校正,并采用8种波段组合方式进行水深遥感反演。研究结果表明:（1）4种大气校正模型均可在一定程度上削弱大气对水体信号的影响;因参数选取以及研究区水体组分的不同,不同模型的校正结果存在一定差异;两类水体反射率峰值分别出现在蓝波段与绿波段;（2）6S大气校正模型鲁棒性较强,该模型因研究区水体组分发生变化导致对应的水深反演结果与其余模型相比波动较小;FLAASH模型在海洋型和城市型两种气溶胶模式水深反演结果在浑浊水体存在较为明显的差异,辽东浅滩浅水区平均相对误差相差7.9%;ACOLITE模型受水体类型影响显著且对浑浊水体具有优越性与稳定性,平均相对误差较FLAASH降低5.6%;（3）多波段水深反演精度普遍优于单波段,但反演精度与波段数目之间无显著的相关性;水深反演波段组合方式对不同研究区敏感性不同,清洁水体三波段模型的反演精度较好,浑浊水体中四波段模型的反演精度最优,平均相对误差较三波段模型降低达5.6%。 相似文献