共查询到19条相似文献，搜索用时 218 毫秒
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对安装在海上风电钢管桩基础上的升降式网箱结构的波浪场特性进行研究,掌握升降式网箱结构内部及结构后方水体的运动特征及速度场变化情况。基于OpenFOAM软件包开发了波、流与孔隙介质结构相互作用的数值计算模型,将网箱结构按等效阻力简化为多孔介质结构,开展升降式网箱结构的波浪场特性研究。研究结果表明：网箱结构对流体具有一定的阻流作用,网箱结构内部速度场得到一定程度的减小,网箱结构背浪侧也有一定的速度衰减区域;对比网箱结构顶部不同潜深条件下的网箱结构内部流场特征,网箱结构顶部潜深在1/4D~1/2D（D为水深）范围内网箱结构内部流场速度最小、流场最为稳定、速度分布均匀,网箱结构向浪侧前方和背浪侧后方流场波动较小。所得结论表明在钢管桩基础上安装升降式网箱结构时需要关注的网箱结构对流场特性的影响,充分考虑网箱结构阻力对流速的作用,掌握极端工况下升降式网箱结构保持优良养殖环境需要下潜的高度范围,以保障升降式网箱的安全。 相似文献
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为了促进深远海养殖装备朝智能化方向发展,解决电能供给困难的问题,克服抗风浪网箱受波流耦合作用对太阳能和风能利用的局限性的问题,针对养殖区域的低流速海域,提出了一种适用于深远海可升降网箱的横轴半潜式潮流能发电装置,建立了Savonius型水轮机叶片受力数学模型,分析了叶轮中心与水面的距离对水轮机捕能效率的影响,利用Fluent软件数值模拟了导流增速浮体的速度场情况,设计了发电装置整体结构及锚泊系统,搭建了发电装置试验模型,开展了物理模型试验,测试了不同水流速度情况下与叶轮相对离水距有关的各参数变化情况,并对试验数据进行分析。试验结果表明,在不同的水流流速下,随着离水距的不断增加,捕获功率呈先增加后减小的趋势,当叶轮中心高出水面1/4个叶轮直径时,叶轮的输出功率最大。 相似文献
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目前深远海网箱养殖已成为我国海水鱼类养殖的一个重要方向,为获得适合于深远海养殖的最优网箱结构,本文利用数值模拟方法,对投放于黄海冷水团的"钻石型"网箱箱体设计了5种结构方案(方案1～方案5),进行水动力特性数值模拟,分析箱体结构的中部水平漂移、底部水平漂移以及网箱阻力等特性变化。研究表明,在流速为1m/s时,网箱中部水平漂移优化效果好的依次为方案5(减少30.59%)和方案2(减少20.23%),底部水平漂移优化效果好的依次为方案2(减少37.33%)和方案5(减少22.39%),网箱阻力优化效果好的依次为方案5(减少12.98%)和方案4(减少9.15%)。研究结果表明,采用刚性底框、方形网目,中部增加刚性圆环,网箱形状为上大下小的圆台形,有利于减小网箱的横向位移,降低网箱的阻力。研究结果可为深远海重力式网箱设计提供技术参考。 相似文献
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网箱养殖生态学研究进展 总被引：3，自引：0，他引：3
网箱养殖生态学是水产养殖生态学的重要分支,是研究网箱养殖生物及养殖活动与养殖水体环境相护作用关系、依据当地环境状况为养殖设施建设及养殖活动管理提供理论指导的科学。本文简述了网箱养殖活动的历史沿革,重点介绍了网箱养殖生态学在养殖水环境管理、养殖容量评估和深远海养殖领域的研究进展。在此基础上,对网箱养殖生态学的未来研究方向进行了展望,以期为水产养殖活动的相关研究提供参考。 相似文献
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HDPE圆形升降式网箱下沉时最大倾角的研究 总被引：4，自引：0，他引：4
分析了1种HDPE双浮管圆形升降式网箱的沉降过程,并利用几何分析方法找出该升降式网箱沉降的最大倾角与网箱系统参数之间的关系,制作1个圆形升降式网箱模型,在静水池中进行沉降实验。试验过程中,通过水下摄像及图像处理软件找出网箱沉降时的最大倾角。模型网箱最大沉降倾角的理论计算值为22.77(°),实验观测值20.80(°),二者误差为9.4%,最大倾角的理论计算值和试验测量值基本吻合,说明理论计算方法是可行的。据此,计算出国内常用的周长40 m的HDPE双浮管圆形升降式网箱的最大沉降倾角为31.29(°)。并以周长40 m的双浮管HDPE圆形升降式网箱的尺度参数作为参考,分析该网箱浮绳框边长、沉降水深和网箱直径与网箱最大沉降倾角的关系,得出这三者与沉降倾角呈线性关系的结果,为HDPE双浮管圆形升降式网箱的设计及安全操作提供了理论依据。 相似文献
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面向深远海网箱养殖需求,基于高精度温盐深测量仪、无线数据传输网络、监测信息实时处理与集成等关键技术,设计了与深远海大型智能化养殖网箱配套的海洋环境监测系统,实现温度、盐度、溶解氧等海洋环境要素的远程实时监测. 相似文献
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一种基于有限元原理的养殖网箱耐流特性的数值计算方法 总被引：2，自引：1，他引：2
对养殖网箱在海流作用下变形而导致的网箱养殖空间减少的有效把握,是网箱设计计算的核心课题之一。本文提出1种基于有限元原理的用于预测养殖网箱耐流特性的数值模拟方法,以期依据计算机模拟结果,在一定程度上代替传统的模型试验和海上实际测试,寻找提高网箱耐流特性的技术措施和解决方案。 相似文献
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黄岛湾是青岛开发区重要的旅游海区，附近建有海滨公园、友谊宾馆等旅游观光配套设施。近年来，部分渔民在湾内水面上搭建养殖筏架、养殖网箱，严重破坏了海域的旅游景观，影响了过往船舶的航行安全。对此，青岛开发区海监大队联合黄岛街道办事处和边防武警开展联合行动，对辖区黄岛湾海域非法搭建的养殖筏和养殖网箱等设施进行了清理整治。通过清理整治，既有效维护了海域使用秩序，又使黄岛湾旅游区海域恢复了海域原貌，再现了往日宜人的美丽风光。 相似文献
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基于渤海和南海的海洋平台设计环境条件,分析了近年来我国近海极端海洋环境条件的发生规律及其对海洋平台疲劳设计条件的冲击。采用Miner’s线性累积疲劳损伤准则和疲劳可靠性理论,研究了极端海况引起的疲劳损伤对海洋平台疲劳寿命的影响,提出了考虑极端海洋环境条件的海洋平台疲劳设计方法。研究表明,由于近年来全球气候变换带来的极端气象条件频发,导致海洋工程结构经历传统意义上的多年一遇海洋环境条件的概率大大增加,使得现行的海洋平台疲劳设计条件偏离了实际的海洋环境条件。数值算例表明,极端海况引起的疲劳损伤在总的疲劳损伤的比例大大增加,甚至成为疲劳损伤的主要部分。因此,这些极端海况引起的疲劳损伤对结构疲劳寿命的影响不容忽略,考虑极端海洋环境条件的海洋平台疲劳设计符合近年来的灾害性海况频发的现状。 相似文献
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The increasing global demand for animal protein is a major ecological concern due to its impacts on land use, climate change, global grain supply and fisheries. One method for harvesting animal protein is to grow marine fish. This is widely practiced in coastal environments, but also leads to environmental problems associated with habitat loss and nutrient loading. One alternative is to move marine aquaculture further offshore, away from coastal land-use conflicts and towards ocean currents, which can efficiently dispose wastes. This concept creates a logistical challenge, however, since operators have to transport large amounts of food, fish and fuel to and from offshore cages on a regular basis and in varied weather conditions. In this paper, we discuss the economic feasibility of using offshore oil and gas platforms as bases for open ocean aquaculture in the Gulf of Mexico. We develop net-present value models of a platform-based operation and describe sensitivity analysis of the model output. We conclude that offshore platform-based mariculture may be commercially viable under favorable assumptions, that its viability requires economies of scale and depends principally on the yield per unit of cage volume achieved. The limitations of the analysis are described. 相似文献
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Since offshore towers are high-cost, high-risk structures, reliability analysis is of great importance in their design. This paper presents a possible practical approach to certify a design through selective critical member reliability estimates. After a brief review of current research in this field, the authors outline a procedure for reliability estimation of structural members in extreme stress and fatigue limit states. A spectral approach for the extreme response statistics with stochastic loading is described. The reliabilities are computed by the Level II first-order second moment (advanced) method. The fatigue reliability is estimated with a narrow-banded stress assumption with discrete, but significant sea states within the life of the structure. Two numerical examples, a three shallow water model and a two-dimensional deep water model are presented along with the influences of stochastic variables (sea state, current, tubular member diameter) on reliabilities (extreme stress and fatigue damage). 相似文献
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The paper describes a novel approach to the problem of estimating the extreme response statistics of a drag-dominated offshore structure exhibiting a pronounced dynamic behaviour when subjected to harsh weather conditions. It is shown that the key quantity for extreme response prediction is the mean upcrossing rate function, which can be simply extracted from simulated response time histories. A commonly adopted practice for obtaining adequate extremes for design purposes requires the execution of 20 or more 3-h time domain analyses for several extreme sea states. For early phase considerations, it would be convenient if extremes of a reasonable accuracy could be obtained based on shorter and fewer simulations. The aim of the work reported in the present paper has therefore been to develop specific methods which make it possible to extract the necessary information about the extreme response from relatively short time histories.The method proposed in this paper opens up the possibility to predict simply and efficiently both short-term and long-term extreme response statistics. The results presented are based on extensive simulation results for the Kvitebjørn jacket structure, in operation on the Norwegian Continental Shelf. Specifically, deck response time histories for different sea states simulated from an MDOF model were used as the basis for our analyses. 相似文献
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HDPE深水网箱抗风浪流性能的海区验证试验 总被引：5，自引：0，他引：5
对HDPE深水网箱2000～2004年间的抗风浪流性能进行了海区验证试验.通过对HDPE深水网箱扶栏、框架、网具以及固泊系统受损率的统计,根据扶栏、框架、网具以及固泊系统在整个深水网系统中的重要程度,分别给予一定的权重统计出深水网箱的整体受损率,能比较客观地反映深水网箱的抗风浪流性能.海区验证试验结果表明,HDPE深水网箱抗风力达35 m/s、抗浪高6 m、抗流速1.0 m/s,与其设计参数基本相同.同时,为了增加HDPE深水网箱的抗风浪流性能,建议扶手管从110 mm改为125 mm、主浮管从250 mm改为300 mm、扶栏高度从1 m降低为0.8 m或0.6 m.风力主要影响扶栏系统,流速主要影响网具系统,而波浪对HDPE圆形浮式深水网箱的框架、网具、固泊系统以及网箱整体结构均有明显影响. 相似文献
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重力式与碟形网箱的锚绳受力特性比较 总被引：6，自引：0，他引：6
针对常见的重力式、碟形和拟碟形网箱在不同下潜深度状态下的锚绳受力特性进行了试验研究.试验共设模型4组,分别在纯流、纯波以及波流联合条件下进行.测力通过系缚于锚绳底端的4个拉力传感器获得.试验结果表明水流作用力的大小在很大程度上受网箱结构形式的影响,而在波浪条件下其影响相对较小.重力式网箱的配重形式及下潜形式对网箱的受力具有重要影响.另外,网箱在波流组合条件下的受力并不是纯流及纯波单独作用下的简单叠加.最后,在综合比较网箱价格和性能的前提下,对网箱结构形式的选择进行了一些讨论,并提出若干建议. 相似文献
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《Marine Policy》2013
This study presents the response of fisheries management to the extreme climatic events that affect marine capture fisheries and mariculture in Taiwan. Two regional approaches that can be applied universally to help capture fisheries and mariculture adapt to extreme weather events are also proposed. In the winter of 2008, an anomalously strong and continuous northeasterly wind caused by a La Niña event drove the cold China Coastal Current southward to penetrate the southern Taiwan Strait, and a portion of this current intruded eastward to the southern Penghu Archipelago. The cold current intrusion appreciably damaged marine aquaculture and the wild fish population, causing the death of more than 73 t of wild fish and 80% of cage aquaculture fish at the Penghu Islands. This extremely cold seawater event occurred between late January and the beginning of February 2008. To recover fishery resources around the waters of Penghu, fishery-related agencies adapted recovery measures over 3 years starting in April 2008 that included hatchery juvenile release, environmental monitoring, fishery subsidies, and ecological field investigations. This study suggests that responding to extreme climatic influences on fisheries and mariculture should include (1) establishing an early warning system by connecting fisheries agencies and marine research institutions to assist decision makers in performing time-adaptive measures, (2) temporarily suspending fishing activities after the occurrence of a natural disaster to help recover fishery resources and ecosystems, (3) altering the governance of farming fishing right so that fish farmers can temporarily transfer their aquaculture cages from high-risk areas to waters outside the influence of extreme weather events, and (4) continually filing surveys to understand the recovery status of marine ecosystems. 相似文献
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深水网箱投饵机设计与试验研究 总被引：15，自引：0，他引：15
根据网箱养殖的特点,结合网箱养殖的经验,设计了1种深水网箱投饵机,并进行了相应的试验,测定了不同情况下产生的真空度以及在冲饵管和吸饵管不同开度时的下料时间。此投饵机使用水力环流供饵、水力抽负吸饵、水动力投饵,充分利用了丰富的海水资源,用汽油机水泵作动力,利用管道将饵料抛向网箱,可向多个、距离不同的网箱供饵。作为1种新的投饵机具,可用于网箱养鱼和池塘养鱼的投饵。 相似文献