An ecosystem-based framework for governance and management of maritime cultural heritage in the USA     

Stefan Claesson 《Marine Policy》2009

A new federal administration, alongside initiatives proposed by the President's US Commission on Ocean Policy, provides a timely and critical opportunity for maritime archaeologists and cultural resource managers to re-consider management frameworks for maritime cultural heritage in the USA. Policy is urgently needed that defines governments’ roles and responsibilities in protecting and managing maritime cultural heritage in federal waters. Implementation of a regional governance structure based on the tenets of ecosystem-based management is proposed in this paper to manage and develop these resources effectively. Through regional governance, the maritime heritage of the USA can be conserved for future generations, keeping its citizens connected to deep-rooted maritime traditions and contribute to the well-being, economic growth and development of coastal communities.  相似文献   

浅议东莞航道1︰2000水下地形测量工程实践经验     

卢秀明  曾涛  郭强 《四川测绘》2009,32(1):23-25

本文以东莞市某航道水下地形测量为例,介绍了GPS-RTK配合测深仪技术在水下地形测量中的应用.依据项目特点,结合作者多年从事水下地形测量工作的经验,对创建国家级"文明样板航道"水下地形测量顺利实施提出了几点建议.  相似文献   

Estimation of near-field characteristics of tsunami generation by submarine landslide   总被引：3，自引：0，他引：3  

A. Najafi-Jilani  B. Ataie-Ashtiani   《Ocean Engineering》2008,35(5-6):545-557

Underwater landslide can trigger impulsive waves with high amplitude and run-up, which may cause substantial damage. In this work, the experimental investigations are performed to study the impulsive wave characteristics caused by underwater landslides. The effects of landslide geometry and kinematics on wave characteristics are studied by performing 84 laboratory experiments. The influences of thickness, volume and shape of failure mass on the characteristics of initial wave are discussed. The impacts of water body conditions such as the slope of sliding bed and the initial submergence of underwater landslide are also examined. The present experimental data as well as the available data in the literature are used to provide an applied method for prediction of the initial wave amplitude. The present prediction method is properly verified by several experimental, numerical and real case data.  相似文献   

Application of the ALE technique for underwater explosion analysis of a submarine liquefied oxygen tank   总被引：1，自引：0，他引：1  

Jae-Hyun Kim  Hyung-Cheol Shin 《Ocean Engineering》2008,35(8-9):812-822

The design of submarines has continually evolved to improve survivability. Explosions may induce local damage as well as global collapse to a submarine. Therefore, it is important to realistically estimate the possible damage conditions due to underwater explosions in the design stage. The present study applied the Arbitrary Lagrangian–Eulerian (ALE) technique, a fluid–structure interaction approach, to simulate an underwater explosion and investigate the survival capability of a damaged submarine liquefied oxygen tank. The Lagrangian–Eulerian coupling algorithm, the equations of state for explosives and seawater, and the simple calculation method for explosive loading were also reviewed. It is shown that underwater explosion analysis using the ALE technique can accurately evaluate structural damage after attack. This procedure could be applied quantitatively to real structural design.  相似文献   

Laboratory investigations on impulsive waves caused by underwater landslide   总被引：4，自引：0，他引：4  

B. Ataie-Ashtiani  A. Najafi-Jilani 《Coastal Engineering》2008,55(12):989-1004

Laboratory investigations have been performed on the submarine landslide generated waves by performing 120 laboratory tests. Both rigid and deforming-slide masses are considered. The effects of bed slope angle, initial submergence, slide geometry, shape and deformation on impulse wave characteristics have been inspected. Impulse wave amplitude, period, energy and nonlinearity are studied in this work. The effects of bed slope angle on energy conversion from slide into wave are also investigated. Laboratory-based prediction equations are presented for impulse wave amplitude and period in near and far-field and are successfully verified using the available data in previous laboratory and numerical works.  相似文献   

水声定位技术的发展现状与展望   总被引：22，自引：1，他引：21  

李守军  包更生  吴水根 《海洋技术学报》2005,24(1):130-135

文章简述了传统的3种声学定位系统的工作原理、系统构成以及各自的优缺点,分别举例说明了市场上典型产品的性能、应用情况,并重点介绍了当前声学定位技术发展的新情况,预测了声学定位技术在未来的发展趋势。  相似文献   

The limitations of diversity metrics in directing global marine conservation     

《Marine Policy》2014

Biodiversity hotspots have been used extensively in setting conservation priorities for marine ecosystems. A recent Nature publication claims to have uncovered new latitudinal gradients in the evenness of reef communities and new reef hotspots based on functional diversity. Simulation models show that the purported evenness gradient is a mathematical inevitability of differences in species richness and detectability between vastly different marine ecosystems, namely ‘reefs’ in tropical, temperate, and polar regions. Constraints on evenness, along with disparity amongst communities in possible functional traits, cast doubt on the utility of global functional diversity comparisons for management of marine systems.  相似文献   

Numerical modeling of ground borehole expansion induced by application of pulse discharge technology     

Hyunku Park  Seung-Rae Lee  Tae-Hoon Kim  Nak-Kyung Kim 《Computers and Geotechnics》2011

Pulse discharge technology (PDT) is an innovative technique that can be used to enhance bearing capacity of piles and resisting capacity of anchors. It enlarges the section area and compacts the surrounding soil by high-powered shock wave pressure induced by an underwater electrical discharge. This study aims to establish a suitable numerical model for the simulation and prediction of ground borehole expansion induced by PDT. In order to examine the relationship between electricity and the characteristics of shockwaves generated by PDT, laboratory pulse discharge tests were performed using PDT equipment used in current practice. Then, based on the underwater explosion (UNDEX) model and a coupled acoustic–structural analysis scheme, the results of laboratory PDT tests were analyzed and numerically benchmarked to determine the equivalent UNDEX model parameters for providing shock loading input in a ground borehole expansion simulation. A series of expansion simulations for undrained clayey and sandy soils were performed, and the predicted borehole expansion behaviors were compared with the test results. Moreover, a parametric study was conducted to examine the effects of soil properties on the expansion behavior. The results of the numerical work in this study appeared to be consistent with field test results published in the literature and showed that the soil characteristics related with packing, state of stresses, and degree of saturation were important when analyzing borehole expansion behavior.  相似文献   

Underwater glider modelling and analysis for net buoyancy, depth and pitch angle control     

Nur Afande Ali Hussain  Rosmiwati Mohd-Mokhtar 《Ocean Engineering》2011,38(16):1782-1791

Underwater glider is an autonomous underwater vehicle that glides by controlling their buoyancy and attitude using internal actuators. By changing the vehicle's buoyancy intermittently, vertical motion can be achieved. Characteristics of glider motion include upward and downward movement in a saw tooth pattern, turning and gliding in a vertical spiral motion and gliding without using thrusters or propellers. This paper presents the modelling and identification on net buoyancy, depth and pitching angle of an underwater glider system. A ballast tank subsystem is considered appropriate for the identification process since it is the main parameter for the motion control. By selecting the ballast rate as the input, three aspects of the dynamics of a glider can be observed: buoyancy, depth of the glider and pitching angle. The MATLAB System Identification Toolbox^TM is used to obtain a mathematical model of the glider ballast-buoyancy, ballast-depth and ballast-pitching angle conditioning system. The best three parametric estimation models are chosen, and the results of the comparison between simulated and estimated outputs are presented. The information obtained from the modelling and identification approaches are used for USM's Underwater Glider Prototype controller design. The information observed during this procedure are utilised for optimisation, stability, reliability and robustness analysis of the underwater glider.  相似文献   

集成深拖与AUV对洋中脊热液喷口的联合探测     

周建平  陶春辉  金翔龙  李怀明  邓显明  顾春华  何拥华 《热带海洋学报》2011,(5)

热液喷口探测是目前国际上的热点,探测技术方法也多种多样。阐述了集成深拖与自治水下机器人(Autonomous Underwater Vehicle,AUV)探测技术,重点介绍了集成深拖的组合特性。针对热液喷口的探测需求,根据集成深拖与AUV两种方法的优点,提出两种技术方法的联合探测。以一个实际探测的区块为例,讨论了两种方法联合探测的实效性。指出该技术方法可更快速地探测热液的异常范围,同时可降低AUV下潜的盲目性,也可以减少AUV的下潜次数,节约了海上调查时间,提高探测效率。最后指出了现场探测与数据分析需进行深拖位置校正和关注底流及地形对热液羽状流空间分布的影响两个重要问题,为未来的热液探测提供了指导作用。  相似文献