单点系泊船舶运动的仿真研究

应用计算机仿真方法，研究了潮流作用下系泊系统的运动响应。建立了三自由度运动微分方程。然后在仿真工具箱SIMULINK中建立了时域仿真模型。对系泊船只的运动进行了计算机仿真。给出了其运动响应的时间历程，讨论了系统刚性对系泊运动的影响，利用Liapunov理论分析了静止系泊位置的稳定性，指出了定性分析方法对于系泊系统设计的意义。     

热处理工艺对22MnCrNiMo钢闪光焊缝耐蚀性能的影响

研究了880～960℃二次循环淬火,560～640℃ 20～40 min回火对R4s （22MnCrNiMo）级系泊链钢闪光焊缝区人工海水耐蚀性能的影响。结果表明,920℃2次淬火+600℃回火时,钢的焊缝腐蚀速率和腐蚀深度达到最低。确定出最佳淬火温度、回火温度和回火保温时间为920℃,600℃和30 min,腐蚀速度在30天时为0.030 g/（m²·h）,60天时为0.032 g/（m²·h）,90天时为0.43 g/（m²·h）     

锚杆桩、“孔桩”、条基共同工作的设计实例

本文通过泉州地区某单位控制楼的基础方案变更的实例,阐述不同型式的基础按变形协调原理共同工作的设计方法。原设计挖孔桩因渗水过大,孔壁稳定等原因无法实现。修改方案由柱下交梁基础、已成挖孔桩护壁侧阻与锚杆静压桩共同承担荷载。在变形协调的条件下,只需各承载构件引起的土体变形均控制在一定界限内,则总的沉降就一定能控制在该界限内。已建成的工程沉降观测结果较好地证实了这种设计处理方法的正确性。     

Sea-ice management and its impact on the design of offshore structures

A methodology for including ice-management in a structural reliability analysis is presented. The approach mainly focuses on how icebreakers or offshore installation disconnection capabilities may alter ice-load distributions and thereby reduce the probability of failure. To demonstrate the approach, a moored symmetrical structure in the central Barents Sea was considered. Realistic ice data from a probabilistic ice-drift simulator was used as a basis and ice loads were calculated in hourly time steps for a 1000-year period. The load calculations were based on the transformation of all developing ice conditions into a standardized equivalent ice thickness. Furthermore, empirical formulations for ice resistance on icebreaking vessels were combined with “max-to-mean ratios” from physical tank-model tests to estimate peak loads.The demonstration reveals a need for more relevant ice-load models that are valid both for managed as well as unmanaged ice. The methodology used for the calculation of ice equivalency and ice loads significantly underestimates the loads from severe ice features (compared to approaches recommended in ISO 19906). In a severe ice environment, it was found that the icebreaker's ability to reduce ice loads was insufficient to reduce the most extreme (abnormal) loads. The ability to disconnect moorings and risers and escape the site prior to abnormal ice events will ensure that the ice loads are within an acceptable range, conditional that the disconnection capabilities are sufficiently reliable. A fault-tree analysis including failure probabilities in ice-management operations and/or disconnection operations is considered useful for estimating the frequency of specified accidents.     

两组海洋深水潜标系统的对比分析

通过对同一航次的两组海洋深水潜标系统进行对比分析,总结了要成功收放深水潜标,在设计上和投放中所应注意的问题,更好地指引今后的科考工作。     

Experimental study of the functionality of a semisubmersible wind turbine combined with flap-type Wave Energy Converters

In the present paper the functionality of the Semisubmersible wind energy and Flap-type wave energy Converter (SFC) is examined experimentally. In order to study the functionality of the SFC, the focus is on operational environmental conditions. SFC is a combined concept that utilizes offshore wind energy and ocean wave energy for power production. Details are presented as far as the physical modelling of the wind turbine with the use of a redesigned small-scale rotor and of the Power Take-Off mechanism of the Wave Energy Converters (WECs) with the use of a configuration that is based on a mechanical rotary damper. Tests with quasi-static excitation, motion decay, regular and irregular waves without and with wind that is uniform are conducted on an 1:50 scale physical model. The experimental data are compared with numerical predictions obtained by a fully coupled numerical model using Simo/Riflex tool. A good agreement is observed between experimental and numerical predictions. The combined operation of WECs doesn't affect the tension of mooring lines nor the acceleration of nacelle and the bending moment in tower's base. The produced power of the WECs of the SFC and consequently the functionality of the SFC is estimated.     

内转塔式FPSO局部强度分析研究

以“南海奋进”号FPSO为对象,运用MSC／Patran、MSC／Nastran程序系统,对其所采用的内转塔式单点系泊系统进行局部受力分析,了解各个载荷对船体结构的影响。     

Stochastic Analysis of a Single-Degree-of-Freedom Nonlinear Experimental Moored System Using an Independent-Flow-Field Model

Stochastic characteristics of the surge response of a nonlinear single-degree-of-freedom moored structure subjected to random wave excitations are examined in this paper. Sources of nonlinearity of the system include a complex geometric configuration and wave-induced quadratic drag. A Morison-type model with an independent-flow-field formulation and a three-term-polynomial approximation of the nonlinear restoring force is employed for its proven excellent prediction capability for the experimental results investigated. Wave excitations considered in this study include nearly periodic waves, which take into account the presence of tank noise, noisy periodic waves that have predominant periodic components with designed additive random perturbations, and narrow-band random waves. A unified wave excitation model is used to describe all the wave conditions. A modulating factor governing the degree of randomness in the wave excitations is introduced. The corresponding Fokker–Planck formulation is applied and numerically solved for the response probability density functions (PDFs). Experimental results and simulations are compared in detail via the PDFs in phase space. The PDFs portray coexisting multiple response attractors and indicate their relative strengths, and experimental response behaviors, including transitions and interactions, are accordingly interpreted from the ensemble perspective. Using time-averaged probability density functions as an invariant measure, probability distributions of large excursions in experimental and simulated responses to various random wave excitations are demonstrated and compared. Asymptotic long-term behaviors of the experimental responses are then inferred.     

基于像素层标识点的双边滤波快速实现

为实现船舶缆绳载荷短期高精度预测,提出一种将小波多尺度分解重构法与BP神经网络组合建模的预测算法。该组合算法利用小波多尺度分解重构法对非平稳的船舶缆绳载荷序列进行分解重构计算,将非平稳的原始缆绳载荷序列转化为多层较平稳缆绳载荷序列分量,再利用BP神经网络预测算法对各层分量建立预测模型,以实现短期预测计算。仿真结果表明:该组合算法实现了缆绳载荷的短期高精度预测,具有较强的细分与自学习能力,能够满足工程中对缆绳载荷预测精度的需要。     

基于小波神经网络的船舶缆绳载荷预测方法

在船舶缆绳载荷准确预测的研究中,由于船舶缆绳载荷不仅受到风、流、浪等环境因素的影响,还受到船舶的船型、受风面积、吃水大小等因素的共同影响,因此具有较强的随机性和复杂性,是一种非平稳的时间序列,传统的神经网络预测模型在进行负荷预测过程中,无法处理这种非平稳信号导致很难进行准确测量.提出一种基于小波神经网络的船舶缆绳载荷预测方法,算法结合小波分析的时频局部特性与聚焦特性和神经网络的自学习、自适应和推广能力,将小波基函数作为神经网络的隐含层节点的传递函数,建立小波神经网络预测模型,以船舶缆绳的采集数据作为模型的输入与输出,利用小波函数处理非平稳信号的能量,解决缆绳负荷的非线性问题,凭借神经网络小区域计算能力,对预测结果进行进一步优化.仿真结果表明,小波神经网络用于船舶缆绳载荷数据处理,精度满足要求,具有良好的适用性.