引入PLSA模型的光学遥感图像舰船检测   总被引：2，自引：0，他引：2  

周晖  郭军  朱长仁  王润生 《遥感学报》2010,14(4):672-686

提出一种基于概率潜在语义分析(Probabilistic Latent Semantic Analysis,PLSA)的检测算法,首先通过PLSA将目标表述为潜在成分的概率组合,然后利用统计模式识别方法对获取的潜在成分概率进行判别,从而完成最终的检测。其中,生成的潜在成分反映了目标与特征之间相互出现的频率关系,并以潜在成分在目标中概率差异的形式对上述不对应现象给出了直观描述。实验结果表明,所提出的算法对多种复杂情况下的光学图像舰船检测具有很好的准确性和鲁棒性。  相似文献   

基于无人船测量系统的水下地形测量研究与应用     

许成义  孙栋  张金营  陈建忠  孙如瑶  沈孝永 《山东国土资源》2023,39(2):50-55

随着测深技术、GNSS技术、高精密传感器集成化的发展,无人船测量系统为水下地形测量提供了新的思路。结合山东省高密市王吴水库,探讨了无人船水下地形测量的作业流程,通过对比分析,选择最优测线间距获取数据,通过差值分析进行精度评价,数据处理后对成果进行展示。研究区结果表明,无人船测量系统基于单波束测深在中型水库中的应用是十分理想的,测深数据质量较好,能够很好地反映库区的水下地形情况,无人船测量系统在水下地形测量中起着重要作用。  相似文献   

Application of advanced system identification technique to extract roll damping from model tests in order to accurately predict roll motions     

《Applied Ocean Research》2017

In this paper our previously developed advanced system identification technique [1] has been applied to extract the frequency dependent roll damping from a series of model tests run in irregular (random) waves. It is shown that this methodology accurately models the roll damping which can then be used to produce accurate predictions of the ships roll motion. These roll motion predictions are not only more accurate than the potential flow predictions but more accurate than potential flow models corrected using either empirical prediction methods [2] and even those corrected using roll damping obtained from free decay sallying experiments. This methodology has the potential to significantly improve roll motion prediction during full scale at sea trails of vessels in order to dramatically improve safety of critical operations such as helicopter landing or ship to ship cargo transfer.  相似文献   

广东吴川吴阳古沉船为明代古船文献考析     

陈国威 《广东海洋大学学报》2012,(2):21-26

广东吴川吴阳镇是国家级的历史文化名镇,境内历史文物众多.因濒临南海,自古为雷州半岛与外界交往的海洋通道.据考察研究及文物普查,该镇存在着一处古沉船遗址.沉船年代未明,一说为唐宋船,一说为近代外国船.通过民俗、历史地理遗迹调查,结合相关历史文献,论证吴阳古沉船为明代古船的可能性,甚至为17世纪荷兰古沉船.古沉船的历史信息不仅丰富了雷州半岛与域外交往的历史,而且为今后进一步开展雷州半岛航海史考古特别是古沉船考古奠定了文献基础  相似文献   

雪龙船南北极考察走航图的制作   总被引：6，自引：0，他引：6  

徐汉卿  朱建钢  薛怀平  廖小韵  刘根友  郝晓光 《测绘科学》2005,30(6):97-98

“雪龙船南北极考察走航图”是采用新编《系列世界地图》制作的成果。极地考察是一项全球性的重要的科学活动,雪龙船是我国目前唯一的极地科学考察破冰船,表现雪龙船极地科学考察航行路线的走航图,将成为我国南北极考察活动与社会公众沟通的新形式和重要媒介之一。  相似文献   

关于来流对槽道推进器流体动力性能影响的研究   总被引：1，自引：0，他引：1  

张潞怡  徐玉如 《海洋工程》1995,(1)

作为主动操纵装置的船艏侧推器，其侧推效率受船速的影响会有很大的变化。为能有效地进行操纵控制，本文从理论和实验两方面人手，研究了艏侧推器受船速影响的流体动力性能，并在一定的速度范围内，获得了一种理论估算方法。  相似文献   

利用船测数据以及Landsat-7 ETM+影像评估南极海冰区AMSR-E海冰密集度   总被引：3，自引：1，他引：2  

席颖  孙波  李鑫 《遥感学报》2013,17(3):514-526

利用第26次中国南极科学考察期间收集的海冰密集度船基观测资料以及由Landsat-7 ETM+得到的海冰密集度来验证AMSR-E南极海冰区海冰密集度产品的精度。AMSR-E海冰密集度与船基目视观测的海冰密集度存在着一定的线性关系(R²=0.816), 但两者匹配得并不是很好。与ETM+海冰密集度相比,AMSR-E数据趋向于低估海冰密集度,在25景晴空条件下的ETM+影像中,平均海冰密集度偏差(AMSR-E海冰密集度-ETM+海冰密集度)从-5.33%到-21.5%,而相应的均方根误差RMSE (Root Mean Squared Errors)从13.7%到33.8%。依据Landsat-7 ETM+ 海冰分类,AMSR-E数据海冰密集度最大的误差产生于新冰区。  相似文献   

Numerical analysis and validation of weakly nonlinear ship motions and structural loads on a modern containership     

Myung-Jae Song  Kyong-Hwan Kim 《Ocean Engineering》2011,38(1):77-87

This paper aims to validate a numerical seakeeping code based on a 3D Rankine panel method by comparing its results with experimental data. Particularly, the motion response and hull-girder loads on a real modern ship, a 6500 TEU containership, are considered in this validation study. The method of solution is a 3D Rankine panel method which adopts B-spline basis function in the time domain. The numerical code is based on the weakly nonlinear scheme which considers nonlinear Froude-Krylov and restoring forces. The main focus of this study is given to investigate the nonlinear characteristics of wave-induced loads, and to validate this present scheme for industrial use in the range of low Froude number. The comparisons show that the nonlinear motions and hull-girder loads, computed by the present numerical code, have good overall agreements with experimental results. It is found that, for the better accuracy of computational results, particularly at extreme waves in oblique seas, the careful treatment of soft-spring (or compatible) system is recommended to the control of non-restoring motions such as surge, sway, and yaw.  相似文献   

NNFFC-adaptive output feedback trajectory tracking control for a surface ship at high speed     

Li-Jun Zhang  Xue Qi 《Ocean Engineering》2011,38(13):1430-1438

An adaptive output feedback controller based on neural network feedback-feedforward compensator (NNFFC) which drives a surface ship at high speed to track a desired trajectory is designed. The tracking problem of the surface ship at low speed has been widely investigated. However, the coupling interactions among the forces from each degree of freedom (DOF) have not been considered in general. Furthermore, the influence of the hydrodynamic damping is also simplified into a linear form or neglected. On the contrary, coupling interactions and the nonlinear characteristics of the hydrodynamic damping can never be neglected in high speed maneuvering situation. For these reasons, the influence of the nonlinear hydrodynamic damping on the tracking precision is considered in this paper. Since the hydrodynamic coefficients of the surface ship at high speed are very difficult to be accurately estimated as a prior, it will be compensated by NNFFC as an unknown part of the tracking dynamics system. The stability analysis will be given by the Lyapunov theory. It indicates that the proposed control scheme can guarantee that all the signals in the closed-loop system are uniformly ultimately bounded (UUB), and numerical simulations can illustrate the excellent tracking performance of the surface ship at high speed under the proposed control scheme.  相似文献   

舟山海域淡水资源调查岩心钻探技术     

郑荣耀  卢秋平 《探矿工程》2013,40(5):26-30

舟山海域淡水资源调查项目DZS1孔,水深15 m、钻孔深度达202.1 m,在以粘土层和砂层为主的第四系覆盖层全孔取心、在风化基岩层取心2 m。在第四系覆盖层不下套管直接利用φ127 mm钻具进行绳索锤击取心钻探,基岩采用φ127 mm钻具作为套管、φ50 mm钻具单动双管回转取心钻探。介绍了该孔的主要施工工艺与质量控制方法,包括勘探船抛锚定位、潮汛对钻杆的影响、钻探取心过程控制、用取心钻头不取心扫孔技术、更换钻头技术、泥浆工艺等。  相似文献