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简要介绍了琼州海峡500 kV海底电缆地形地貌特点及保护方式,分析了侧扫声呐及多波束检测的基本原理,对侧扫声呐在海底电缆裸露及悬空检测的原理进行了重点阐述。结合海南联网500 kV海底电缆近几次检测数据,通过侧扫声呐地貌检测结果,重点对海底电缆裸露情况、抛石坝及铸铁套管保护状况、海底电缆周围异常进行了分析,能够正常检测出海底电缆的裸露、抛石坝的坍塌及周围异物等异常情况。通过多波束地形检测结果,分析了海底电缆路由区域整体地形状况及抛石坝整体状况、通过Kriging插值方法生成不同的DEM(数字高程模型,Digital Elevation Model),分别从宏观和微观角度对海底电缆路由区域地形冲淤变化进行了分析,并对沙波稳定性进行了分析。结论认为,部分区域地形冲刷严重,容易造成海底电缆裸露、悬空,需要及早关注并采取防冲刷措施。 相似文献
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多波束数据的海底数字地形模型构建 总被引：11，自引：0，他引：11
提出大批量多格式原始多波束数据的DTM构建方法，以满足大区域、大比例尺海底地形制图的需要。在多种格式原始多波束数据接口和系统内部标准数据结构的基础上，通过对数据文件、数据种类和数据运算量的有效组织管理，实施边读入、边权重配赋的网格插值，分析了高斯、指数和距离平方反比权重函数的适用性，及最小值、最大值和平均值的实用性。在权重配赋网格插值基础上，提出分形fBM和张力样条配合使用的方程式插值方法，保证DTM数据的有效外延和地形分辨。整套算法效率高，并能有效保证DTM的精度，对存储在外部介质的数据遍历一次即可完成网格插值。 相似文献
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基于多波束测深的地形定位是水下潜器导航技术研究和发展的重点,多波束测深数据的高精度快速重采样是水下地形匹配定位的前提。传统的实时抽稀方法因对多波束测深数据模型的过分简化而效果欠佳。参考Douglas-Peucker算法和点云数据抽稀方法,采用角度-弦高联合准则对多波束每ping数据进行抽稀处理,参考导航地形图对抽稀后的多ping数据基于点云离散度进行二次抽稀处理,从而实现多波束测深数据的高精度快速抽稀处理。典型的数学仿真地形和实测多波束条带数据实验表明:文中提出的抽稀方法数据抽稀率仿真地形在85%以上,实测地形在90%以上,数据抽稀前后点云构成的曲面DEM误差在3%以内,并且算法实时性较好。 相似文献
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针对单波束测深数据插值模型精度验证困难等问题,利用潮间带潮汐规律,提出了一种基于高精度无人机数据验证插值模型精度的方法。在低潮时利用无人机摄影测量构建高精度潮间带数字表面模型,高潮时获取单波束测深数据并结合全球导航卫星系统技术计算得出潮间带地形点的三维坐标,使用克里金插值法、反距离权重法、规则样条函数法以及自然邻域法分别构建潮间带数字高程模型。以无人机数字表面模型数据为基准,分别对4种插值方法构建的潮间带数字高程模型进行精度分析。结果表明：1)后处理差分技术辅助无人机摄影测量可以构建高精度潮间带数字表面模型。2)在潮间带区域可以使用无人机数据作为单波束测深数据精度的评价标准。3)潮间带地形较为平坦时,规则样条函数法相比于其他3种插值方法精度更高,粗差率为12.5%。 相似文献
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洋中脊是板块扩张和洋壳增生的主要区域,除了发育沿洋脊走向的裂隙式喷发火山脊,还分布有众多零星的中心式喷发火山锥。这些火山锥的形态和分布对了解洋中脊构造和岩浆活动具有重要的指示意义。基于海底多波束地形数据,采用人工或机器解译方法可以识别这些火山锥。本文利用大洋24航次船载多波束测深获得的卡尔斯伯格脊DEM(数字高程模型)数据,以非监督分类为手段,开展洋中脊火山锥的自动提取方法研究。基于原始DEM计算地形坡度、地表粗糙度、正负地形等衍生参数,进行特征变换,提取火山锥的特征信息。使用ISO(迭代自组织)聚类方法对特征变换后的图像进行聚类分析,并利用景观形状指数进行几何筛选,完成火山锥的自动提取。所使用的海底火山锥自动识别方法,正确率达0.8,重叠率约0.7,识别效果较好,效率高,能够在海底大范围的火山锥解译中发挥重要作用。 相似文献
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The identification of potential coastal inundation caused by future sea level rise requires not only time series records from tide gauges, but also high-quality digital elevation models (DEMs). This study assesses the importance of DEM vertical accuracy in predicting inundation by sea level rise along the Valdelagrana beach and marshes of the Bay of Cádiz (SW Spain). A present-day (2000) and a projected (2100) high tide have been spatialized over a traditional (aerial photogrammetry) regional DEM of Andalusia with a horizontal spatial resolution of 10 m and a vertical accuracy of 0.68 m RMSE (root mean square error), and a LIDAR-derived DEM of the Valdelagrana study site with the same spatial resolution but a vertical accuracy of 0.205 m RMSE. The simulations are based on a bathtub model, which accounts for the effect of vertical barriers. The results reveal that the presence of infrastructures such as roads and salterns is the key to delimit the extent of water penetration during high tides in an otherwise homogeneously flat area comprising the beach and marshes of Valdelagrana. Moreover, in comparison with the highly accurate LIDAR DEM, the inundation areas derived from the lower-resolution DEM are overestimated by 72 % and 26 % for the present-day and future scenarios respectively. These findings demonstrate that DEM vertical accuracy is a critical variable in meaningfully gauging the impacts of sea level rise. 相似文献
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The waterline detection method (WDM) based on satellite images is one of the most effective methods for constructing digital elevation models (DEMs) for tidal flats. The general practicability of the WDM has been demonstrated in previous studies for small areas. This article attempts to generate a DEM over a large offshore sandbank with a tidal flat area of more than 620 km2 by integrating the conventional WDM with a hydraulic model and multitemporal satellite images. For illustration purposes, a case study was conducted at the Dongsha sandbank, one of the largest sandbanks among the radial tidal sand ridges of Jiangsu Province, China. In this study, 34 multitemporal satellite images acquired at different tidal phases in 2006 were analyzed to detect the waterlines. The water level at each satellite overpass moment was simulated by a south Yellow Sea hydraulic model, and discrete waterline points were combined with the corresponding water levels to produce a topographic map. Compared with the DEM produced during the same period by the airborne light detection and ranging (LiDAR) data, the DEM derived from WDM effectively contains the average height error within 47 cm, which is satisfactory. All of these findings may be useful for researchers and local authorities, as the findings could be used as a reference for sandbank evolution research or to support environmental management, coast protection, and storm forecasting. 相似文献
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In the field of offshore oil and gas engineering, the arrangement of multiple pipelines are becoming more common, the spacing between the pipelines and the incoming stream velocity will significantly affect the scouring process around the pipelines. In this study, the effect of space ratio (G/D) and the stream velocity on the scouring process around two pipelines in tandem are investigated using the coupled approach of computational fluid dynamics (CFD) and discrete element method (DEM). Here G is the spacing between the pipelines and D is the diameter of the pipeline. Specifically, the effect of space ratio and the stream velocity are discussed by simulating the gap ratio (G/D) between two pipelines ranging from 1 to 3 with an interval of 1, under the stream velocity U = 0.5,1 and 2 m/s, The results indicate that when G/D ≤ 2, the equilibrium scour depth below the upstream pipeline (S1) is slightly larger than that under the downstream pipeline (S2), S1 and S2 slightly increase as the gap ratio increases. Whereas for G/D > 2, the equilibrium scour depth beneath the upstream pipeline is slightly smaller than that under the downstream pipeline, S1 and S2 slightly decrease as the gap ratio increases. Furthermore, the scour depths are highly dependent on and positively related to the incoming stream velocity, the equilibrium bed profiles are similar under the same incident stream velocity with different gap ratios. 相似文献
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采用计算流体力学—离散元耦合方法（CFD-DEM）模拟海底管道床面的冲刷过程。经过模型验证,该方法的计算结果与前人的研究具有较好的一致性,证明其可以应用于海底管道周围的冲刷模拟计算。冲刷初期的结果增强了目前对启动阶段粒子运动机理的理解,即管前后压力梯度造成的渗流作用导致粒子运动。对完整冲刷过程的模拟中,发现冲刷分为冲刷启动阶段、间隙冲刷阶段和尾迹冲刷阶段。间隙冲刷阶段管道下方粒子具有较大速度,冲刷坑快速向下方发展。进入尾迹冲刷阶段后,管道后方出现周期性脱落的涡旋,沙丘上的粒子速度更大。同时利用DEM更具直观性的独特优势,首次得到了14个典型位置处颗粒的运动轨迹和运动速度,对于理解冲刷过程中粒子的运动情况具有较大帮助。 相似文献
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吊舱推进装置在极地船舶中被广泛应用,其转舵模块可以带动螺旋桨摆动从而产生任意方向的推进力,使船舶操纵更为灵活。提出了一种吊舱推进船舶冰区操纵的离散元方法,对具有吊舱推进装置的冰区船舶破冰过程进行了数值模拟。以“雪龙2”号破冰船为研究对象,计算分析了船舶定速直航时的冰阻力,并通过与Lindqvist经验公式的对比验证了冰阻力计算的合理性。在此基础上进一步对船舶在不同冰厚、不同吊舱转向角下的回转破冰运动进行了离散元模拟,分析了回转半径与船长比值随冰厚的变化规律。计算结果表明：船舶的回转性能随冰厚的增大而降低,并随吊舱转向角的增大而显著提高。 相似文献
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GPU-Based DEM Simulations of Global Ice Resistance on Ship Hull During Navigation in Level Ice 总被引：1，自引：0，他引：1
The ice resistance on a ship hull affects the safety of the hull structure and the ship maneuvering performance in icecovered regions.In this paper,the discrete element method(DEM)is adopted to simulate the interaction between level ice and ship hull.The level ice is modeled with 3D bonded spherical elements considering the buoyancy and drag force of the water.The parallel bonding approach and the de-bonding criterion are adopted to model the freezing and breakage of level ice.The ship hull is constructed with rigid triangle elements.To improve computational efficiency,the GPU-based parallel computational algorithm was developed for the DEM simulations.During the interaction between the ship hull and level ice,the ice cover is broken into small blocks when the interparticle stress approaches the bonding strength.The global ice resistance on the hull is calculated through the contacts between ice elements and hull elements during the navigation process.The influences of the ice thickness and navigation speed on the dynamic ice force are analyzed considering the breakage mechanism of ice cover.The Lindqvist and Riska formulas for the determination of ice resistance on ship hull are employed to validate the DEM simulation.The comparison of results of DEM,Lindqvist,and Riska formula show that the DEM result is between those the Lindqvist formula and Riska formula.Therefore the proposed DEM is an effective approach to determine the ice resistance on the ship hull.This work can be aided in the hull structure design and the navigation operation in ice-covered fields. 相似文献
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一种基于TIN三角网数据的规则格网生成算法 总被引：2，自引：0，他引：2
格网地形模型和7TIN地形模型是数字高程模型的两个主要组成部分。结合实际工作，在实现多分辨率地形环境仿真需求下，充分利用已知TIN数据信息，通过划分格网点，判断格网点是否落在TIN三角网内，用三角形三个点高程内插得到格网点高程的方法，实现基于TIN数据生成格网数据。方法简单实用，在三维地形仿真应用中有较好的效果。 相似文献