近自由面水下爆炸冲击波切断效应研究

近自由面水下爆炸形成的冲击波到达自由面时会反射稀疏波,并伴随着水面的上升、破碎和飞溅等复杂物理现象。文章基于无网格SPH方法建立了近自由面水下爆炸数值模型,开发了计算程序,模拟了冲击波和自由面反射的稀疏波的相互作用过程,分析了切断现象的特性、产生机理以及对冲击波参数的影响。研究发现,爆心正上方且距自由面较近处,稀疏波作用最强;近自由面爆炸冲击波冲量可衰减为无限水域爆炸的1/3左右。文中的研究旨在探索冲击波在自由面处的传播规律,并为近自由面水下爆炸载荷的确定提供参考。     

水下爆炸冲击波和气泡脉动的数值模拟研究

运用AUTODYN程序对水下爆炸冲击波和气泡脉动进行了数值模拟研究.首先模拟了无限水域中的水下爆炸冲击波,然后将深水爆炸简化为一维问题,采用一维方法对深水爆炸冲击波和气泡脉动进行了数值模拟,并将模拟结果与经验公式和实验结果进行了比较.模拟结果表明,AUTODYN能准确模拟近场水下爆炸冲击波和深水爆炸气泡脉动过程,计算得到的近场水下爆炸冲击波峰值压力和比冲量、水质点速度、气泡最大半径、脉动周期、二次压力波的峰值压力和比冲量等特性参数均与经验公式、理论公式和实验结果吻合良好.远场的冲击波峰值压力的计算值小于经验值,而且计算误差随着爆距的增加而增大.最后总结了模拟结果,得出了对工程应用有益的结论.     

水下爆炸冲击波的载荷强度计算

应用商业有限元软件MSC.DYTRAN,比较了2种耦合方法(ALE and General Coup ling),分析计算了球形药包在近似无限水域中爆炸产生的冲击波。对比分析了在不同参数设置下冲击波的传播过程。通过将计算结果与经验公式相比较,证明了MSC.DYTRAN软件是一种合适的模拟水下爆炸冲击波传播的计算分析软件。     

船舶在远场水下爆炸载荷作用下动态响应的数值计算方法

提出了一个利用MSC／DYTRAN数值模拟水面船舶在远距离水下爆炸载荷作用下动力响应的方法。用FORTRAN语言编译用户子程序，在近场水域边界处加上冲击波载荷以模拟远场爆炸效应，进而利用DYTRAN中强大的流固耦合计算功能，计算船体在水下冲击波作用下的动态响应。同时研究了边界定义和单元划分对冲击波传播的影响。该方法弥补了DYTRAN计算远场水下爆炸的某些不足，计算所得到的船体附近的自由场压力与经验公式的结果基本一致，船体的冲击响应与相关实验结果比较表明本文计算结果可信。     

基于SPH方法的水下爆炸初始爆轰过程研究

炸药的水下爆炸具有极大的变形和高度的非均匀特性,基于网格的数值模拟方法研究这类问题时遇到诸多困难,将最近发展起来的无网格的光滑粒子流体动力学(SPH)应用到炸药的水下爆炸初始爆轰过程的研究.从模拟结果可知,应用SPH方法能较好地预测出爆轰波的大小和形状以及在爆轰过程中的压力分布.SPH方法非常适宜处理炸药的水下爆炸极短瞬时所具有的大变形和高度的非均匀动力学的极端情形,这对进一步模拟水下爆炸过程提供了一种新的研究方法.     

水下非接触爆炸作用下舰船结构损伤评估

由于水下爆炸和舰船结构动态响应的复杂性,水下非接触爆炸作用下舰船结构损伤研究主要来自于对试验现象或试验数据的分析。传统对水下爆炸作用下舰船结构损伤研究的理论分析和计算过程主要考虑水下爆炸冲击波和2次压力波。本文提出了气泡脉动对舰船结构的冲击,明确了气泡脉动对舰船结构损伤的关系;在综合研究水下非接触爆炸作用下舰船结构损伤模型基础上,建立了舰船结构的损伤等级,确定了等级评估标准;举例与模拟试验情况下舰船结构损伤情况进行对比,结果基本吻合。     

舰船舷侧防爆结构在内部爆炸作用下破裂的数值模拟

文章通过应用MSC.Dytran中的多欧拉一拉格朗日耦合方法,对反舰武器战斗部进入舷侧防爆结构内部爆炸作用下其变形和破坏的情况进行数值模拟研究.用多欧拉域模拟结构内外空气中爆炸冲击波传播情况.用快速一般耦合方法计算结构和流体的耦合作用.模拟结果显示:在冲击波作用下,防护结构外层舱室变形、失效后破裂,冲击波通过破口流入内层舱室.由于文中考虑了结构破坏与爆炸冲击波的相互作用,使得数值模拟方法和结果更符合实际.通过对爆炸冲击波动能与结构吸能的研究发现,除了结构的直接吸收削弱了冲击波的动能以外,通过破孔和舱壁上预开的孔泻掉的能量相当于结构总吸能的46.7%.因此在舰船舷侧防护结构设计时考虑内舱壁的适当开孔并减小强度是有益和必要的.     

SPH方法模拟水下爆炸研究进展

对SPH方法模拟舰船水下爆炸的主要技术问题及其研究现状进行分析。结果表明,大密度比多相流模拟、三维或基于对称算法的三维模拟、无反射边界等边界的处理是SPH方法实现舰船水下爆炸工程应用的主要技术瓶颈。提出SPH方法实现舰船水下爆炸工程应用的重点研究方向。     

接触爆炸下舰船强力甲板塑性动态响应特性研究

基于舰船强力甲板结构和接触爆炸工况设计,采用非线性有限元计算方法对在不同炸药量下、不同尺寸的纵桁和强横梁的强力甲板进行接触爆炸数值模拟。分析球形炸药接触爆炸下空气冲击波的压力分布以及对甲板的冲击过程,结果显示强力甲板结构在接触爆炸下呈现出3种破坏模式,并通过定义构件相对强度因子,提出了破坏模式的判别条件,初步揭示舰船强力甲板在接触爆炸下的塑性动态响应特性。     

水下爆炸冲击载荷的一种新型算法研究

近年来,越来越多的研究者都重视使用计算机的数值模拟对水下爆炸进行研究.水下爆炸包含了一系列复杂的物理过程,如大变形、高度非均匀性、可变形边界和自由表面.对于传统的基于网格的数值方法,水下爆炸问题的模拟是一项非常具有挑战性的工作.介绍了无网格光滑粒子流体动力学(SPH)方法在水下爆炸模拟中的应用,并且提出了处理固壁和物质交界面的算法,给出了水下爆炸过程具有代表性瞬间的压力分布、速度分布以及气泡的演变和脉动,为舰船水下爆炸冲击载荷的计算提供了一种新型有效的研究方法.     

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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33rd International Conference on Ocean,Offshore and Arctic Engineering （OMAE2014）

正San Francisco,California,June 8-13,2014.OMAE 2014 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;·to exchange ideas and experiences whilst promoting technological progress and its application in industry·to promote international cooperation in ocean,offshore and arctic engineering.In line with the tradition of excellence of previous OMAE conferences,more than 900 technical papers are planned for presentation.Outreach for Engineers Specialty Forum This Specialty Forum is designed for students and professionals who may not be familiar with the Ocean and Offshore industry,as well as those who have just recently specialized in this field.     

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。     

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.     

The 11th International Conference on Hydrodynamics (ICHD 2014)

正19–24 October 2014 SingaporeCONFERENCE THEMES The overall aim of the ICHD Conference is to provide a forum for participants from around the world to review,discuss and present the latest developments in the broad discipline of hydrodynamics and fluid mechanics.The first International Conference on Hydrodynamics(ICHD)was initiated in 1994 in Wuxi,China.Since then,9 more ICHD conferences were held subsequently in Hong Kong,Seoul,Yokohama,Tainan,Perth,Ischia,Nantes,Shanghai and St Petersburg.Evidently the ICHD conference has become an important event among academics,researchers,engineers and operators,working in the fields closely related to the science and technology of hydrodynamics.The 11th ICHD will be held in Singapore in 2014.     

第十二届深水操作会议和展览会(英文)

正November 4-6,2014Moody Gardens HotelConvention Center/Galveston,TX The Deepwater Operations Conference and Exhibition is celebrating its 12th anniversary this year.This growing event will continue the tradition of excellence in addressing operational challenges involved in developing deepwater resources.We will return to the Moody Gardens Hotel and Convention Center on November 5-7,2014 in Galveston,Texas.     

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）.     

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.     

某海港码头的撞损修复

依据码头撞击受损区域调查检测结果,对受损构件提出合理的修复方案,为码头的安全运行提供保障。