A Unified Computational Method for Simulating Dynamic Behavior of Planing Vessels

High speed planing hulls have complex hydrodynamic behaviors. The trim angle and drafts are very sensitive to speed and location of the center of gravity. Therefore, motion simulation for such vessels needs a strong coupling between rigid body motions and hydrodynamic analysis. In addition, free surface should be predicted with good accuracy for each time step. In this paper, velocity and pressure fields are coupled by use of the fractional step method. On the basis of integration of the two-phase viscous flow induced stresses over the hull, acting loads (forces and moments) are calculated. With the strategy of boundary-fitted body-attached mesh and calculation of 6-DoF motions in each time step, time history of ship motions including displacements, speeds and accelerations are evaluated. For the demonstration of the software capabilities, circular cylinder slamming is simulated as a simple type of water slamming. Then, a high-speed planing catamaran is investigated in the case of steady forward motion. All of the results are in good concordance with experimental data. The present method can be widely implemented in design as well as in performance prediction of high-speed vessels.     

A Time Domain Computation Method for Dynamic Behavior of Mooring System

A quasi-steady time domain method is developed for the prediction of dynamic behavior of amooring system under the environmental disturbances,such as regular or irregular waves,winds and cur-rents.The mooring forces are obtained in a static sense at each instant.The dynamic feature of the moor-ing cables can be obtained by incorporating the extended 3-D lumped-mass method with the known shipmotion history.Some nonlinear effects,such as the influence of the instantaneous change of the wettedhull surface on the hydrostatic restoring forces and Froude-Krylov forces,are included.Thecomputational results show a satisfactory agreement with the experimental ones.     

测量船动态吃水测量方法研究

针对测量船特别是中大型测量船的动态吃水问题,提出了单船和双船载波相位差分GPS测定方法,给出了动态吃水计算公式。根据装备现状,对比分析了三种测量方法的适用范围,例举了典型参数值的动态吃水观测误差,旨在为测量作业人员提供借鉴和参考。     

海洋调查船业务化运行保障关键技术进展

海洋科学的发展和海洋战略重要性的日益凸显对海洋调查船的业务化运行提出了新的要求。从国内外海洋调查船运行和关键技术两方面的发展现状和趋势出发,提出了我国"十三五"期间海洋调查船业务化运行保障关键技术的发展建议。为解决海洋调查船需求不断增大与船舶建造运行成本限制的矛盾,世界各主要海洋国家均采取措施提高调查船的使用效率,组建海洋调查船队,实行船时统一调配。另一方面,多学科多任务的海洋调查方式的发展,以及新型调查观测设备的应用,促使调查船运行保障关键技术趋向于普适性和更强的现场支持功能。据此,在我国海洋调查船业务化运行发展原则、关键技术发展方向等方面提出了建议。     

Optimal Design for Main Dimensions of a 75000t Floating Production and Storage Vessel

The basis, process and results of the demonstration of the main dimensions of a 75000t floating production and storage vessel are discussed in this paper. A simple but reliable orthogonal design method is applied in the main dimension optimization. The ideas of gradual approximation and feedback from various aspects are put into effect. During the demonstration, in order to make the model tally with the actual situation, the draft design is closely related to the computational analysis, so that the demonstration model can be verified at any time; the handling of the overall system is closely related to the research of each item, which is beneficial not only to the mastery of various regularities, but also to the balance of decisions. Finally, according to the computational results and the regularities obtained from analysis, the main dimensions are determined.     

A Method for Calculation of Low-Frequency Slow Drift Motions Based on NURBS for Floating Bodies

Through a higher-order boundary element method based on NURBS (Non-uniform Rational B-splines), the calculation of second-order low-frequency forces and slow drift motions is conducted for floating bodies. In the floating body′s inner domain, an auxiliary equation is obtained by applying a Green function which satisfies the solid surface condition. Then, the auxiliary equation and the velocity potential equation are combined in the fluid domain to remove the solid angle coefficient and the singularity of th...     

Domain decomposition and matching for time-domain analysis of motions of ships advancing in head sea

A domain decomposition and matching method in the time-domain is outlined for simulating the motions of ships advancing in waves. The flow field is decomposed into inner and outer domains by an imaginary control surface, and the Rankine source method is applied to the inner domain while the transient Green function method is used in the outer domain. Two initial boundary value problems are matched on the control surface. The corresponding numerical codes are developed, and the added masses, wave exciting forces and ship motions advancing in head sea for Series 60 ship and S175 containership, are presented and verified. A good agreement has been obtained when the numerical results are compared with the experimental data and other references. It shows that the present method is more efficient because of the panel discretization only in the inner domain during the numerical calculation, and good numerical stability is proved to avoid divergence problem regarding ships with flare.     

基于AIS的海洋环境目标监测技术研究

介绍了由多种AIS监测平台获取船舶信息的方法,探讨基于AIS的海洋环境目标监测技术。介绍了AIS信息获取和融合技术,提出了同类传感器多源融合与异类传感器多源融合的模型,描述了船只目标信息提取与应用技术。通过收集处理AIS信息,可以大大扩展船舶的监视范围,对于提高船舶动态的监控能力和海上安全的保障能力具有很重要的意义。     

一种水声定位数据后置处理方法

文章给出了定位数学模型和递推最小二乘算法,并且讨论了数据后置处理的过程和最小二乘法在数据后置处理中的应用,最后详细介绍了水池试验数据的处理结果。实验结果表明,利用递推最小二乘法能够有效地对定位结果进行平滑处理。     

A Semi-Analytical Method for the PDFs of A Ship Rolling in Random Oblique Waves

The PDFs (probability density functions) and probability of a ship rolling under the random parametric and forced excitations were studied by a semi-analytical method. The rolling motion equation of the ship in random oblique waves was established. The righting arm obtained by the numerical simulation was approximately fitted by an analytical function. The irregular waves were decomposed into two Gauss stationary random processes, and the CARMA (2, 1) model was used to fit the spectral density function of parametric and forced excitations. The stochastic energy envelope averaging method was used to solve the PDFs and the probability. The validity of the semi-analytical method was verified by the Monte Carlo method. The C11 ship was taken as an example, and the influences of the system parameters on the PDFs and probability were analyzed. The results show that the probability of ship rolling is affected by the characteristic wave height, wave length, and the heading angle. In order to provide proper advice for the ship''s manoeuvring, the parametric excitations should be considered appropriately when the ship navigates in the oblique seas.     

二维非结构三角网格节点的动力配置法

用Delaunay三角化法构造网格,需要事先配置好节点.文中给出1种新的节点配置方法,即动力配置法.其主要思路是设网格尺度函数已配置,根据尺度函数计算出所需的单元数和节点数.把这些节点随机配置在计算域内,节点之间存在斥力,力的大小与当地的尺度函数正相关.节点在力的作用下运动,达到平衡时节点从局部看是均匀的,从整体上依尺度函数分布.最后用Delaunay三角化法构造网格并适当修改.试验结果表明,该方法形成的网格从单元形状和尺度,对边界的拟合3个方面都能达到较高的质量.     

A Study of a Short-Baseline Acoustic Positioning System for Offshore Vessels

The underwater position of the beacon determined using the conventional mode of the short-baseline acoustic positioning system (SBL system) is usually incorrect due to the inaccuracy of underwater-measured sound speed, which is affected by the environment. This article presents a corrected mode of SBL system to offer a precise solution for the underwater beacon position. The corrected mode using the formulation of Euclidean geometry converges quickly and efficiently, obtaining the precise position of the beacon. Finally, a simulation of coring missions of a vessel is presented to verify the accuracy of the corrected mode of the SBL system.     

用DGPS双天线系统校验定位辅助设备的方法探讨

随着GPS技术的快速发展,使用DGPS定位的精度越来越高,这就为物探船上定位辅助设备的精确校准与校验提供了可能.通过对发现六号物探船定位辅助设备的校准与校验,初步形成了一套比较可行的作业方法.此文结合校验方法及其可行有效性分析,详细阐述了校验方法,并试图对校验误差来源进行探讨,以期提高对定位辅助设备校准与校验的精确度.     

航天测量船坞内标校基准计算的新方法

GPS测量直接获得点位的精确三维坐标,通过空间直角坐标系、大地坐标系、站心地平直角坐标系、站心极坐标系等一系列转换,再加入大气折光差改正和垂线偏差改正,就可以快速获得设备标校所需的精确基准。与采用常规测量方法、分别计算设备标校基准相比,不仅大大减少了工作量,还提高了计算结果的精度。     

基于自动跟踪技术检测GNSS动态测量精度方法

提出一种基于TDA5005高精度全站仪对GNSS定位设备进行自动跟踪测量,通过自动控制、时间同步、姿态改正、空间基准统一等步骤,实现对动态环境下GNSS设备单历元定位精度进行检测。设备检测既可在海上也可在陆地上进行,自动化程度高,操作简便,以期对GNSS的应用有一定的指导和借鉴意义。     

用多波束系统对奥运帆船赛区进行水深地形测量的建议

2008年奥运帆船比赛将在青岛举行。预选赛场如何符合帆船比赛的要求?海底是否有影响运动员安全的障碍物7为此，建议对预选赛场海区进行多波束全覆盖水深地形测量。同时介绍了多波束测深系统的先进性以及在许多海洋工程中的应用。     

一种调整台风参数的方法

本文针对我国海面风数值预报和后报研究，基于现有的实测资料和前人的经验统计，就海面风模式中较敏感的风资料参数对台风最大风速半径的确定提出了一种较客观的统计方法，使之在缺乏观测资料的情况下能合理地反映海面风实况。在这之前，本文对中国《台风年鉴》１９７０年以前偏大的最大风速资料进行了合理的订正，使之在进入海面风数值模式前能真实地代表台风气候特征。     

基于深度学习和时空特征融合的海洋渔船密度预测方法

为了从海量渔船轨迹数据中挖掘隐含的信息和知识,进而为渔业行政主管部门的决策提供科学依据,本研究以AIS渔船轨迹数据为研究对象,提出了一种基于深度学习和面向时空特征融合的海洋渔船密度预测方法：首先,利用渔船轨迹数据集对渔船行驶区域进行网格划分;其次,筛选出渔船高密度区域进行研究,避免数据稀疏性问题;再次,根据渔船轨迹数据的时空分析,构建三维时空融合矩阵;最后,通过卷积循环神经网络模型捕获渔船分布的时间和空间特征,并利用卷积神经网络的堆叠加强对空间特征的学习。实验通过东海海域渔船真实轨迹数据进行具体测试,结果表明渔船密度预测值与真实值非常接近,平均绝对误差为4×10-4,模型较好地拟合了渔船密度分布特征,有效地提高了渔船捕捞热点预测的准确性和鲁棒性。