新型船舶尾轴密封装置设计

本文提出了一种唇口斜置,唇部带双回流的新型船舶尾轴密封环,并介绍了这种环的结构原理、理论分析和设计方法。     

一种新的SAR图像船只检测方法

提出一种新的基于恒虚警率(CFARConstantFalseAlarmRate)技术,确定SAR图像中检测船只整体阈值的方法。该方法采用高斯分布(正态分布)作为SAR图像灰度的概率密度函数,由CFAR技术直接导出用于检测船只整体阈值的计算公式,用记数滤波器滤波去除虚警。该算法避免了复杂公式迭代和求解形状参数计算过程,也避免了用二分法寻找阈值的循环解算过程,提高了检测速度。使用XSAR和ERSSAR图像对该算法进行检验,并与其它算法进行比较,结果显示所提出的算法在检测精度和检测速度上都有明显的改进。     

多环芳烃油指纹应用于船舶溢油鉴别研究

溢油种类主要包括船舶燃料油和原油,二者性质的差异决定了鉴别方法也相应不同,寻求适合于船舶溢油的鉴别方法具有重要意义。在使用柱色谱层析方法对样品进行分离前处理的基础上,以气相色谱/质谱方法(GC-MS)为主要分析手段,对溢油样品和可疑船舶溢油源样品的多环芳烃油指纹特征进行对比,并在多环芳烃油指纹参数的基础上进一步进行多环芳烃内组成三角图分布特征与聚类分析研究,成功为珠江口水域某船舶溢油事故追踪到肇事溢油源。结果表明:取自丁船的油样和现场溢油样芳烃油指纹特征最为相近,是此次溢油事故的溢油源。受风化作用后的船舶燃料油中饱和烃类化合物数量稀少,且含量极低,不适合用于溢油鉴别,而多环芳烃类化合物较饱和烃类化合物而言具有含量高、种类丰富的特点,是该类溢油鉴别的主要油指纹依据。使用油指纹参数进行可疑溢油源识别时,充分考虑油品中有机分子所受风化影响程度的不同是风化条件下溢油鉴定的关键。因此,多环芳烃油指纹可以有效应用于船舶燃料油溢油的鉴别。     

基于舰船耐波性的中国近海海浪特征统计(英文)

海浪是影响舰船行进和结构设计的最核心的环境要素。海浪参数的统计分析是建立舰船环境适应性长期预测模型的基础。对1993-2011年沿海台站、浮标观测资料,高度计观测资料和船舶报观测资料进行双线性插值,给出了海浪波高的分析场。利用波高分析场对WAVEWATCHIII(WW3)模拟结果进行最优插值同化。给出了海浪统计玫瑰图、极端海浪统计参数和海浪累年二维极值海浪谱等与舰船耐波性有关的海浪统计参数,分析了中国近海的波浪特征。     

Interaction between sea ice/iceberg and ship structures: A review

For ship structural design and good maneuverability in an ice-covered sea, the local and global load of ice cover on ships should be well understood. This paper reviews the extensive work done on ice loads on ships, including： （a） Ice pressure and local load determination based on field and model tests; （b） Global ice loads on ships from full-scale field observations, model tests and numerical models under different ice conditions （level ice and pack ice） and ship operations （maneuvering and mooring）. Spe- cial attention is paid to the discrete element simulation of global ice loads on ships; and （c） Analytical solutions and numerical models of impact loads of icebergs on ships for polar navigation. Finally, research potential in these areas is discussed.     

电子航道图标准建设与应用

电子航道图的标准建设与生产应用关系到内河航运的高质量发展动能.分析了电子航道图标准的现状及存在的问题,建立了现有电子航道图标准体系及内河航道地理信息要素的分类方法,结合电子航道图核心要素,建立了典型应用场景,通过完善电子航道图数据标准体系和精细化生产应用,不断提升综合立体交通网的水运比较优势.     

Michell and Hogner models of far-field ship waves

The far-field waves, and the related far-field wave drag, predicted by the Michell or Hogner theories are considered. These two classical theories are found to predict nearly identical transverse waves for all practical cases. However, the Michell and Hogner models predict divergent waves—dominant at high Froude numbers—that can differ significantly. Differences between the far-field waves predicted by the Michell and Hogner models are much smaller for catamarans, for which lateral interferences between the twin hulls overwhelm lateral interferences between the port and starboard sides of the hulls, than for monohull ships. Moreover, differences between the divergent waves predicted by the Michell and Hogner theories are larger for higher Froude numbers, bigger beam/length ratios, smaller draft/length ratios, or larger separation distances between the twin hulls of a catamaran.     

System-based investigation on 4-DOF ship maneuvering with hydrodynamic derivatives determined by RANS simulation of captive model tests

For the non-negligible roll-coupling effect on ship maneuvering motion, a system-based method is used to investigate 4-DOF ship maneuvering motion in calm water for the ONR tumblehome model. A 4-DOF MMG model is employed to describe ship maneuvering motion including surge, sway, roll, and yaw. Simulations of circular motion test, static drift and heel tests are performed by solving the Reynolds-averaged Navier-Stokes (RANS) equations, after a convergence study quantifying the necessary grid spacing and time step to resolve the flow field adequately. The local flow field is analyzed for the selected cases, and the global hydrodynamic forces acting on the ship model are compared with the available experiment data. Hydrodynamic derivatives relating to sway velocity, yaw rate, and heel angle are computed from the computed force/moment data using least square method, showing good agreement with those obtained from EFD data overall. In order to investigate further the validity of these derivatives, turning circle and zigzag tests are simulated by using the 4-DOF MMG model with these derivatives. The trajectories and the time histories of the kinematic variables show satisfactory agreement with the data of free-running model tests, indicating that the system-based method coupled with CFD simulation has promising capability to predict the 4-DOF ship maneuvering motion for the unconventional vessel.     

Discrete elementmodeling of ice loads on ship hulls in broken ice fields

Ice loads on a ship hull affect the safety of the hull structure and the ship maneuvering performance in ice-covered regions. A discrete element method （DEM） is used to simulate the interaction between drifting ice floes and a moving ship. The pancake ice floes are modelled with three-dimensional （3-D） dilated disk elements considering the buoyancy, drag force and additional mass induced by the current. The ship hull is modelled with 3D disks with overlaps. Ice loads on the ship hull are determined through the contact detection between ice floe element and ship hull element and the contact force calculation. The influences of different ice conditions （current velocities and directions, ice thicknesses, concentrations and ice floe sizes） and ship speeds are also examined on the dynamic ice force. The simulated results are compared qualitatively well with the existing field data and other numerical results. This work can be helpful in the shil3 structure design and the navigation securitv in ice-covered fields.     

BD2/GPS四频高精度接收机在远望号船姿测量中的应用

随着我国北斗卫星导航系统建设的逐步完善以及北斗应用的迅速推广,BD2/GPS定位终端设备已经开始广泛地应用于各个领域中.介绍了BD2/GPS双系统四频高精度接收机在远望号测量船船姿测量中的应用;并与传统的单一GPS接收机的测姿精度进行比对,分析北斗卫星导航系统在姿态测量中的作用与优势.