采用Green-Naghdi方程和有限元法计算浅水船波

采用波动方程／有限元法求解Green-Naghdi(G-N)方程计算船舶在有限水深区域的兴波和波浪阻力。把行驶船舶对水面的扰动作为移动压力直接加在Green-Naghdi方程里，以描述运动船体和水面的相互作用，并经此来计算不面波动、船底水动压力和波浪阻力。G－N方程比浅水方程增加一个非线性的频散项，以补充有限水深对浅水船波的影响。采用随船运动网格的有限方法，以Series 60 CB=0.6船作为算例给出浅水船波的计算结果，并与浅水方程的结果进行了比较。计算结果表明，当船速小于临界速度时，由于频散的影响，G－N方程级出的船后尾波波高比浅水方程的结果大，同时波浪阻力也比浅水方程的结果有所提高。当船速大于临界速度时，G－N方程的计算结果与浅水方程基本相同，频率散射无明显影响。     

潜艇近水面航行兴波特征研究

潜艇作为一种水下航行器，其近水面运动时产生的绕流场远比无界直航运动时要复杂得多，其近水面航行时对自由液面的影响不容忽视。本文采用粘性流体力学计算方法，对SUBOFF潜艇近水面航行时的粘性绕流场进行模拟，对自由液面的兴波进行计算，并对波形特点进行深入分析。通过本文的研究，得到潜艇近水面航行时自由液面兴波的特点和相关规律。     

潜艇近水面航行兴波特征研究

潜艇作为一种水下航行器,其近水面运动时产生的绕流场远比无界直航运动时要复杂得多,其近水面航行时对自由液面的影响不容忽视。本文采用粘性流体力学计算方法,对SUBOFF潜艇近水面航行时的粘性绕流场进行模拟,对自由液面的兴波进行计算,并对波形特点进行深入分析。通过本文的研究,得到潜艇近水面航行时自由液面兴波的特点和相关规律。     

滑行艇在规则波中的数值模拟

针对波浪中滑行艇水动力性能预报的不足,提出了一种基于六自由度运动模型的滑行艇水动力性能预报方法,实现其在波浪中自由运动的水动力性能预报。首先根据水波理论利用CFD技术完成了三维数值水池的造波和消波,然后以某型滑行艇为模型,将六自由度方程赋予滑行艇,实现了其在迎浪匀速航行时随波浪的自由运动,最后通过Fluent数值计算得到了其在波浪中自由运动时的阻力、升力、升沉位移、纵倾角以及兴波等流场参数。计算结果表明:利用该方法获得的某型滑行艇的流场参数较真实地反映了滑行艇在波浪中的姿态,为滑行艇耐波性实验提供了一定的理论依据。     

小水线面双体船兴波阻力数值仿真研究

建立小水线面双体船的基本计算模型,分别改变片体吃水、主体长径比、片体间距、支柱长度和支柱与主体最大横剖面间纵向距离,采用SHIPFLOW软件对兴波阻力系数进行数值仿真计算。根据计算结果,分析各船型要素对兴波阻力系数的影响规律,为小水线面双体船的船型设计提供参考。     

采用一种高阶面元法数值求解浅水船舶兴波问题

开发了一种基于B样条的高阶面元法用来求解浅水船舶兴波问题.船体表面和自由面上分别布置Rankine源,同时利用镜像原理来计及水底的影响.物体儿何用B样条曲面精确表示.在求得边界面卜的源强密度分布后,物面上的速度势用B样条来表示.数值计算中采用配置方法,并且用高斯-勒让德公式来计算方程中的积分.为了验证文中方法的有效性,用本方法计算了Wigley船在深水和浅水中的兴波水动力和波形,所得数值结果与试验结果和其它数值结果进行了比较,吻合程度令人满意,表明本方法被用来求解浅水船舶兴波问题是有效的.     

兴波及航态对螺旋桨激振力预报的影响

针对船舶航行时的船体兴波及航态变化,采用RANS方法、VOF方法及船体六自由度运动方程,建立了考虑船体兴波及航态变化时螺旋桨激振力的计算方法。叠模、考虑船体兴波及考虑航态变化时螺旋桨推力、船底板压力计算结果的对比表明:考虑兴波及航态变化时,由于流速变化,螺旋桨推力平均值减小,船底板压力平均值增大;由于来流不均匀程度的变化,1倍叶频处峰值减小;考虑兴波及航态变化时,计算得到的激振力更加接近真实情况,但由于激振力在频域中较为接近,为节约计算量,计算时可不考虑船体兴波及航态变化。     

兴波及航态对螺旋桨激振力预报的影响

针对船舶航行时的船体兴波及航态变化,采用RANS方法、VOF方法及船体六自由度运动方程,建立了考虑船体兴波及航态变化时螺旋桨激振力的计算方法。叠模、考虑船体兴波及考虑航态变化时螺旋桨推力、船底板压力计算结果的对比表明:考虑兴波及航态变化时,由于流速变化,螺旋桨推力平均值减小,船底板压力平均值增大;由于来流不均匀程度的变化,1倍叶频处峰值减小;考虑兴波及航态变化时,计算得到的激振力更加接近真实情况,但由于激振力在频域中较为接近,为节约计算量,计算时可不考虑船体兴波及航态变化。     

直接边界元法时域全非线性兴波计算

文章在时域中采用直接边界元的方法计算模拟了以稳定航速运动的近水面潜体全非线性兴波现象.从格林定理出发,在边界面上布置Rankine源和偶极子,采用时间步进的方法计算模拟潜体近自由面运动的兴波现象.每个时步自由面上的势和节点位置采用全非线性拉格朗日自由面边界条件求解,重新生成自由面网格准备下一个时步计算的初始条件.文中给出了数值计算的结果并与试验和线性计算的结果相比,证实了该方法是可靠的,并可以利用该方法建立数值波浪水池.     

基于Kelvin源格林函数的船舶兴波阻力预报

实现了基于Kelvin源格林函数的实船模型兴波阻力预报,采用自适应数值积分算法处理被积函数的高频振荡。首先介绍了计算所用的数学模型及数值方法,而后将该方法应用于Wigley数学船型,初步验证了方法和程序的正确性.在此基础上计算系列60船型兴波阻力系数,对比试验结果分析了面元上Gauss节点数与数值积分算法选择对计算精度的影响,得出不同数值计算方案优劣的定性结论。针对方尾水面舰船标模DTMB 5415计算兴波阻力系数,所得结果在大部分速度区间内误差控制在5%以下。     

Errata

正In the paper"Influence of Fouling Assemblage on the Corrosion Behaviour of Mild Steel in the Coastal Waters of The Gulf of Mannar,India"in Vol.12,No.4,Page:509,References were lost,and the two authors’biographies were identical.The correct text is shown below.We apologize to the authors and our readers for any inconvenience caused by the errors.     

Journal of Marine Science and Application 2014 Sum. Contents

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第34届海洋、离岸及极地工程国际会议(英文)

正St.John's,Newfoundland,Canada,May 31-June 5,2015 OMAE2015 is the ideal forum for researchers,engineers,managers,technicians and students from the scientific and industrial communities from around the world to: meet and present advances in technology and its scientific support;     

联合作战计划和执行系统

全球指挥控制系统(GCCS)实施当前美国海军网络中心战信息基础设施的联合计划网络。联合作战计划和执行系统(JOPES)支持GCCS实现联合计划。JOPES有两类计划：时间不限的精密预案计划生成作战计划、方案计划或职能计划；时间敏感的危机行动计划生成作战命令或战役方案。前者在和平时期创建的作战计划是后者的计划基础，加速应付危机的能力。     

Eastbound or westbound ?

In terms of equal sailing distances, where is the inflexion when ships depart from ports in the Asian Continent to New York via Suez and/or Panama？
The answer is China South Port Group （Hong Kong, Shenzhen and Guangzhou）.     

Recent progress on wave induced loading measurements in warships

Recent measurements of wave induced hull strain and flexure in RN warships are presented together with the derivation of the current design criteria for extreme hull girder bending loads. The history of the development of the shipboard instrumentation used is given and recent developments to improve the quality and ease of analysis of the data are described. An unexpectedly high transverse asymmetry in the longitudinal strains measured in destroyers is shown to be the result of a combination of vertical and lateral bending in oblique seas. Finally recent theoretical comparisons between the loading of Deep-Vee hulls and conventional UK rounded bilge hulls are presented which demonstrate the higher loading experienced by this type of hull form.     

桥梁防撞设施物理模型试验

物理模型试验是预报防撞设施所受撞击力及优化设计方案的主要方法之一。结合杭州湾大桥柔性防撞设施及东海大桥独立式防撞体设计方案,阐述了船—防撞体撞击试验的基本原理、方法、试验方案及相关试验结果。提出了柔性防撞系统的优化方案。试验结果表明,该方案经济有效,可供预报类似桥梁防撞设施撞击力时参考。     

印尼某电厂码头水工建筑物设计

印尼某电厂项目码头水工建筑物包括码头、防波堤和护岸等主要组成部分。在该项目水工建筑物的设计过程中,综合考虑当地的自然条件、施工能力和材料来源等因素,不断优化结构选型和结构断面。根据不同使用要求,护岸分别采用直立式和斜坡式2种结构型式,推荐的设计方案节省投资、施工方便,可供同类工程设计参考。     

Impact of regulation on the performances of long-distance transport services: A comparison of the different approaches in Sweden and Norway

Despite the many socio-economic similarities between Sweden and Norway, differences in jurisdiction, organisation, cooperation, and financing of long-distance passenger train and coach services have led to the development of four distinctively different ways of serving the markets. This paper describes how the train and coach markets have developed in the two countries, with emphasis on regulatory and industrial structure and a couple of performance variables.Looking at passenger rail, both countries separated infrastructure from operation over a decade ago. However, while Norwegian rail is characterised by an almost monopoly supplier, rail services in Sweden are partly decentralised to the responsibility of county authorities and are widely subjected to competitive tendering. The rest of the network is about to be opened up for on-the-track competition. Swedish Rail (SJ) has spent the last decades consolidating its core business (passenger rail) and sold out its other businesses. In contrast, the Norwegian state rail (NSB) has expanded its business to become a major bus operator and property owner, with extensions also into the Swedish market.The coach industry was more recently deregulated in both countries. The Swedish coach market is dominated by privately owned companies operating services to and from Stockholm. In Norway, state-owned NSB is a major coach operator on medium distance routes, and is also the largest partner of Nor-Way Bussekspress which totally dominates long-distance coach services. Further, the Norwegian coach market is characterised by cross-ownership and cooperation which has enabled an extensive route network which covers most of Norway.We find distinct differences in achievements in the two modes and in the two countries. Swedish rail services have succeeded in winning market shares and in renewing and developing both infrastructure and service levels to a greater extent than the Norwegian model. On the other hand, the Norwegian coach market seems to be more developed and efficient compared to its Swedish counterpart.The paper concludes with a discussion on the possible links between the different approaches and the performance observed, with the aim to stimulate further and more detailed research on some important issues.     

开放式数据挖掘系统模型

目前国内已经出现了少量的数据挖掘相关产品。国内数据挖掘软件无论从数量还是质量上比较，都与国外软件存在着较大的差距。随着数据仓库技术的普及，数据挖掘应用的需求越来越强烈，如何缩短这种差距，研发数据挖掘软件产品成为国内业界的一个重要问题。通过引用目前国际通用数据挖掘标准技术来构建开放式的数据挖掘系统模型，该系统模型从可扩展性、可重用性、易用性等方面得到了加强。