循环载荷作用下损伤船体梁极限强度研究

为了研究循环载荷作用下扶强材初始损伤对其极限强度的影响,进行了14组扶强材的循环加载试验和分析。构造了考虑材料累积损伤完整、断筋和大变形的扶强材单元极限承载力计算公式,提出了相应循环载荷作用下损伤扶强材单元的端缩曲线表达式和船体梁极限强度计算的简化逐步破坏法。编制了循环载荷作用下船体梁损伤极限强度计算程序,进行了船体梁极限强度计算,并与有限元结果进行对比。研究结果表明：改进的损伤扶强材模型可较为准确地描述扶强材材料损伤的完整、断筋和大变形的极限承载力退化情况,扶强材腹板断裂的损伤相较初始大变形及材料累积损伤形式承载力下降程度更明显;所提出的循环载荷作用下损伤船体梁极限强度计算的简化逐步迭代方法,能定量地计算扶强材在不同类型损伤下的极限承载力退化程度,具有较高精度,方便易行,可应用于工程设计。     

钻井利器故事之“保真取样钻具”

天然气水合物作为一种高效清洁能源,广泛分布于海洋和冻土带中。经过近几年的勘探,在我国南海发现了储量非常丰富的天然气水合物资源,并成功进行了试开采,取得了可喜的成绩,也使我国在该领域处于国际领先地位。随着水合物勘探开发程度的进一步加快,作为水合物调查钻探取样的重要利器——保真取样钻具的保真效果已经被越来越多的研究者所关注。本文从科普的角度介绍了天然气水合物保真取样的必要性、国外发展历程及国内近年来的研究成果,以此达到相互交流、相互促进的目的,最终推动保真取样技术的国产化应用。     

基于多源数据和船舶停留轨迹语义建模的港口目标识别

港口目标识别是海事船舶监管的重中之重,船舶自动识别系统（Automatic Identification System,AIS）所获取的船舶活动信息,可为港口目标识别提供高时相和高精度的船舶航行数据。为了探究AIS数据在港口目标识别中的应用,提出一种基于多源数据和船舶停留轨迹语义建模的港口目标识别方法。通过数据挖掘和语义信息增强构建船舶停留轨迹语义模型,识别船舶港口停留轨迹;建立基于随机森林的船舶停留方式分类模型,分类船舶泊位停留轨迹和船舶锚地停留轨迹,并利用空间逐级合并方法提取港口泊位和港口锚地;综合船舶泊位停留轨迹、道路、海岸线、水深、土地利用与土地覆盖等数据,顾及情景-领域知识实现港口目标识别。基于2017年96 790艘船舶的超8300万条AIS轨迹记录,应用本文方法识别南海研究区的港口目标。实验结果表明,本文方法对于船舶轨迹停留行为总体分类精度为0.9477,Kappa系数为0.8948。提取出南海研究区447个港口区域,与Google Earth影像叠加验证结果表明,提取结果均位于真实的港口影像内,相较于Natural Earth数据集中包含的南海区域24个港口点位,提取结...     

三维多层流过山产生的山地重力波研究

为了研究了三维多层气流过山产生的三维山地重力波和大气船波动力学理论,在本文中,改进了一个多层流过山的三维山地重力波的线性理论计算模式,分析了三维多层流过孤立山地产生的三维山地重力波和大气船舶波的物理机制及其表现特征。揭示了多层流过孤立地形产生发散模态和横波两种模态拦截背风波的气象条件,增强了人们对山地重力波动力学的理解和对山脉重力波及其相联系的山脉天气的预测能力。     

一种水声定位数据后置处理方法

文章给出了定位数学模型和递推最小二乘算法,并且讨论了数据后置处理的过程和最小二乘法在数据后置处理中的应用,最后详细介绍了水池试验数据的处理结果。实验结果表明,利用递推最小二乘法能够有效地对定位结果进行平滑处理。     

世界邮轮建造业的空间演化与区位分析

审视世界邮轮建造业的发展过程与区位特征既能揭示邮轮工业空间组织特征,又能为后发国家和地区的邮轮建造及关联产业提供借鉴。运用ArcGIS10.2软件空间叠加与重心模型分析世界邮轮建造业的空间演化与集聚地发现：（1）1900年前全球邮轮造船厂数量很少,1900—1950年伴随邮轮旅游诞生和成长,邮轮工业增速较快,直到20世纪60年代形成现代意义的邮轮制造业,其中尤以意大利芬坎蒂尼集团和德国迈尔集团分别雄踞海洋邮轮、内河邮轮与豪华邮轮建造业榜首。（2）世界邮轮建造业总体呈现吨位大型化、环保节能成为技术攻坚方向等显著特征。经济全球化加速造船企业的兼并重组,邮轮造船厂重组行为主要发生在2000年以后。（3）世界邮轮建造业重心经历了如下历程：1860—1960年集聚于美国东海岸,1961—1990年迁移至欧洲地区,1991年后日本与韩国开始尝试邮轮建造及香港积极收购欧洲邮轮造船厂,但未打破世界主要邮轮造船厂与邮轮运营公司集聚地的“空间错位”特征,印证了邮轮建造业垄断趋势加剧。     

Study on the New Methods of Ship Object Detection Based on GNSS Reflection

This paper presents a study on the new methods of ship object detection based on GPS-R correlation power spectra. Both the principle and the algorithms for recognition are given in detail. The architecture of Doppler Delay Mapping Receiver (DDMR), signal-processing chain, and correlation power spectra discriminant of the reflected signals from the ship object are discussed. Real-time data collection campaigns were done near the sea at Sanya with the Doppler delay mapping receiver mounted on an airplane. Some preliminary experiment results show that the DDMR could work well and can be used in ship object detecting.     

基于EPS2008航迹图制作

通航流量试验研究领导小组在三峡—葛洲坝两坝间组织开展大流量实船试航,我队承担本次任务航迹测量工作。本文提出了航迹数据自动处理流程,基于VB6.0开发航迹处理软件,并基于EPS2008,制作航迹符号。最后,通过实验数据,验证了数据处理的准确性和成图的快速性。     

Domain decomposition and matching for time-domain analysis of motions of ships advancing in head sea

A domain decomposition and matching method in the time-domain is outlined for simulating the motions of ships advancing in waves. The flow field is decomposed into inner and outer domains by an imaginary control surface, and the Rankine source method is applied to the inner domain while the transient Green function method is used in the outer domain. Two initial boundary value problems are matched on the control surface. The corresponding numerical codes are developed, and the added masses, wave exciting forces and ship motions advancing in head sea for Series 60 ship and S175 containership, are presented and verified. A good agreement has been obtained when the numerical results are compared with the experimental data and other references. It shows that the present method is more efficient because of the panel discretization only in the inner domain during the numerical calculation, and good numerical stability is proved to avoid divergence problem regarding ships with flare.     

Experimental Investigation of the Decay from A Ship’s Propeller

In the present study,an experimental investigation of the decay of the maximum velocity and its turbulent characteristics behind a ship propeller,in "bollard pull" condition(zero speed of advance),is reported.Velocity measurements were performed in laboratory by use of a Laser Doppler Anemometry(LDA) measurement system.Earlier researchers described that the maximum axial velocity is constant at the initial stage of a ship’s propeller jet(Fuehrer and Rmisch,1977;Blaauw and van de Kaa,1978;Berger et al.,1981;Verhey,1983) as reported in a pure water jet(Albertson et al.,1950;Lee et al.,2002;Dai,2005),but a number of researchers disagreed with the constant velocity assumption.The present study found that the maximum axial velocity decays in the zone of flow establishment and the zone of established flow with different rates.The investigation provides an insight into the decays of both the maximum velocity and the maximum turbulent fluctuation in axial,tangential and radial components and the decay of the maximum turbulent kinetic energy.Empirical equations are proposed to allow coastal engineers to estimate the jet characteristics from a ship’s propeller.