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简要介绍了将差分GPS技术用于水下地形测绘的方法，重点研究了平面坐标转换和水深数据修正两个关键技术，给出了平面定位的坐标转换方法和考虑水温、含盐度等对声速的影响，以及海水潮位变化等因素后的水深测量修正方法。 相似文献
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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
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《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
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Numerical modeling of ground borehole expansion induced by application of pulse discharge technology
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
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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 ToolboxTM 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
100.
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