海洋平台设计选型的多级模糊优化及非结构性模糊决策分析

针对海洋平台开发设计中经常遇到的复杂的方案优化选型问题, 提出了将多因素、多级非结构性模糊优选理论引入到平台的设计选型中. 根据影响平台选型的非结构性因素, 采用三级模糊优选, 综合考虑了影响平台选型的各种优选目标; 针对影响平台选型优化的因素非常复杂、确定隶属函数主观因素较强的情况, 引入非结构性模糊决策法以确定其隶属度和权重. 通过此模糊优选模型, 进行了一平台的设计选型优化, 得到了比较理想的优选结果, 证明了此模型在为海洋平台方案的设计选型中的实用性.     

海洋平台设计选型的多级模糊优化及非结构性模糊决策分析

针对海洋平台开发设计中经常遇到的复杂的方案优化选型问题，提出了将多因素，多级非结构性模糊优选理论引入到平台的设计选型中，根据影响平台选型的线构性因素，采用三级模糊优选，综合考虑了影响平台选型的各种优选目标，针对影响平台选型优化的因素非常复杂，确定隶属函数主观因素较强的情况，引入非结构性模糊决策法以确定其录属度和权重。通过此模糊优选模型，进行了一平台的设计选型优化，得到了比较理想的优选结果，证明了此模型在为海洋平台方案的设计选型的实用性。     

一种优化模型在登陆兵上船地域选择中的应用

由于在选择登陆兵上船地域过程中存在大量不确定和模糊因素，提出一种基于突变理论的优化选择模型。在简要介绍突变理论基本原理的基础上，建立上船地域优选突变评价指标体系，根据归一公式进行量化递归运算，分别计算出不同方案的总突变隶属函数值，从而确定最优上船地域，并用实例验证了该模型的合理性和可行性。     

模糊多属性决策在舰艇打击海上目标的应用

应用模糊多属性决策理论，提出舰艇扣。击海上多批目标时排序的方法。首先构建威胁评估的指标体系，基于模糊隶属函数对各指标进行量化处理，经过应用模糊多属性决策的理论与方法，准确提供给指挥员打击海上目标的先后顺序，有利于现代海战中实现作战指挥的自动化。     

护航编队对空防御能力分析

在远海护航行动中,为应对空中威胁保护海上生命线,需要对护航编队整体防空能力进行评估,为编队指挥员提供辅助决策。分析影响护航编队整体防空能力的各种因素,建立了护航编队防空的指标体系,应用层次分析法确定指标权重,运用模糊综合评判方法,通过计算各因素的隶属度函数并组成模糊关系矩阵,实现了对护航编队整体防空能力的评估。     

基于P-y曲线法的海上风机三桩基础非线性有限元分析

P-y曲线法是API、DNV等规范推荐的一类分析横向受荷桩的桩土相互作用的方法,它考虑了土的分层特征、不同土类及荷载类型等因素,能较好地反映桩土之间的非线性关系。本文结合某海上风电场建设项目的工程实例,根据P-y曲线法确定了海上风机三桩桩基础与桩周土体间的作用关系;以ANSYS有限元软件为平台,建立了海上风机三桩基础的有限元模型,考虑风机运行荷载、风荷载及波浪荷载共同作用的极端工况,对结构的受力情况进行了分析,确定风机在此工况下能安全运行,为该风电场的设计与施工提供了一定的理论依据与技术参考。     

多因素模糊评价的投标报价决策方法

投标报价决策是承包商中标的关键，而在估算工程成本(包括直接费和间接费)的基础上，确定标高是最困难的，因为报价的策略是受错综复杂的各种因素影响的。本文在多因素分析模型的基础上，提出了一种综合模糊评价的方法，通过专家对影响因素的评定，引入模糊集隶属度函数，得出投标报价的标高，最后通过实际例子来说明这种方法的具体步骤和应用，并指出优点和不足。     

基于模糊多目标决策的舰船防腐蚀工程方案优选模型

文章从模糊多目标决策的基本理论出发,结合舰船防腐蚀工程实际,建立工程方案优选的评价指标体系,通过最小二乘法则计算各待评价方案对模糊理想解的相对隶属度,建立评价模型.在对定性指标模糊白化的基础上将评价指标归一化,完成了工程方案的优选排序.     

人工智能技术在海上风机领域的应用综述

我国海上风机目前发展迅猛，人工智能技术在海上风机领域的应用是当前的研究热点。该文分析总结了多种人工智能技术在海上风机的动力响应分析、运维监测、设计运维优化等多个方向的应用，涉及动力响应预报、功率预报、结构监测、故障诊断、控制优化、运维优化等，分析表明人工智能技术可以较好地应对海上风机设计及运维领域的各项挑战。文中也论述了人工智能技术在海上风机领域的应用前景及目前存在的几种主要限制因素，并展望了未来发展方向。     

导管架式海上风机基础结构优化设计

目前海上风机基础结构存在明显的设计冗余，导致海上风机建造成本过高。为提高经济效益，需要对导管架式海上风机基础结构进行优化设计。该文首先基于海上实测数据对海上风机所处环境载荷进行模拟，得到其时间历程；其次通过有限元方法对平箱梁四桩导管架式海上风机基础结构进行强度校核，发现结构可进行轻量化处理；最后以结构最大平均应力、最大位移和质量为目标响应，通过试验设计（design of experiments, DOE）方法和粒子群算法组合的优化方法，得到结构尺寸对结构目标响应的贡献度和主效应关系，并确定各结构最优尺寸。对海上风机基础结构进行优化设计，能在保证安全的前提下降低建造成本，可为后续海上风机基础结构设计建造提供参数参考。     

海上风电场运维船配备优化方法

海上风电场运维船配备优化是以运维船类型和数量为目标的多目标优化问题。设置近远海风电场和海上风电故障类型两个判别参数，将多目标数学模型简化为包含两个函数变量的单目标模型。海上风电场每月运维工作量函数变量采用反向传播(Back Propagation, BP)神经网络方法求解，而作业窗口期函数变量采用建立海上风电场运维船作业窗口期4维图谱的方式完成取值，完成海上风电场运维船配备优化数学模型的运算流程。海上风电场运维船配备优化可提升海上风电场运维管理系统的智能化程度。     

海上风机支撑结构的时域和频域疲劳对比研究

对海上风机支撑结构进行动力响应分析,求出结构危险节点的载荷谱和功率谱密度函数,结合疲劳损伤模型和Dirlik概率模型,分别在时域和频域内对支撑结构进行疲劳寿命分析.由于时域法计算疲劳寿命需进行应力循环计数,这一过程需处理的数据庞大,耗时长.频域法省去应力循环计数,代之以概率密度函数,可相对准确、快速地计算结构的疲劳寿命.分析结果表明,采用Dirlik概率模型的频域分析法能较准确地反映海上风机支撑结构在随机载荷作用下的疲劳损伤情况,计算结果误差在可接受范围内.     

半潜型浮式风机平台研究综述

介绍了半潜型浮式风机的发展现状,基于已有的概念设计方案提出了半潜型浮式风机平台的初步设计流程图和优化设计方向,综述了半潜型浮式风机平台在稳定性、水动力性能和强度分析等性能方面的研究,提出了在这些研究领域中有待进一步解决的问题。结果表明,目前半潜型浮式风机在技术上已是可行的,但高成本制约了大规模应用,因此需在技术和成本上进一步优化。     

Experimental study on seismic vibration control of an offshore wind turbine with TMD considering soil liquefaction effect

Wind energy is clean and sustainable. Taiwan is establishing offshore wind farms using wind turbines in the Taiwan Strait. However, these are located in an earthquake-prone area with sandy seabed conditions. To ensure their safety and reliability, the turbines’ support structure must be protected against wind, waves, and seismic loads. Tuned mass dampers (TMDs) are commonly employed to reduce structural vibrations. A TMD is more simply incorporated into turbine structures than are other energy dissipation devices. In this study, a 1:25-scale test model with a TMD was constructed and subjected to shaking table tests to experimentally simulate the dynamic behavior of a typical 5-MW wind turbine with a jacket-type support structure and pile foundation. The scaled-down wind turbine model has a nacelle without rotating blades; therefore, the aerodynamic and rotational effects due to the rotating blades were ignored in this study. A large laminar shear box filled with saturated sandy ground was used to simulate the typical seabed conditions of Taiwanese offshore wind farms. The TMD system was designed to be tuned the first-mode frequency of the test model. Two ground accelerations, selected by considering wind farm site condition and near-fault characteristics, were used for excitation in the test. The responses of the test model with and without the TMD system were compared, and the influence of soil liquefaction on the effectiveness of TMD vibration control was addressed.     

Bottom effects on the tower base shear forces and bending moments of a shallow water offshore wind turbine

In this paper the tower base shear forces and bending moments of a shallow water offshore wind turbine have been rigorously calculated by using a nonlinear simulation method taking into account the bottom effects. It has been found that nonlinearly simulated realistic waves with bottom effects should be used as inputs in the stochastic time domain simulation in order to design an un-conservative support structure for the offshore wind turbine. In order to further improve the simulation efficiency, a transformed linear simulation method has been utilized in this paper for generating equivalent waves as those obtained from the nonlinear simulation method. The accuracy and efficiency of the transformed linear simulation method have been convincingly substantiated through the subsequent calculation examples in this article.     

Dynamic ice loads for offshore wind support structure design

For offshore wind farms which are planned in sub-arctic regions like the Baltic Sea and Bohai Bay, support structure design has to account for load effects from dynamic ice-structure interaction. There is relatively high uncertainty related to dynamic ice loads as little to no load- and response data of offshore wind turbines exposed to drifting ice exists. In the present study the potential for the development of ice-induced vibrations for an offshore wind turbine on monopile foundation is experimentally investigated. The experiments aimed to reproduce at scale the interaction of an idling and operational 14 MW turbine with ice representative of 50-year return period Southern Baltic Sea conditions. A real-time hybrid test setup was used to allow the incorporation of the specific modal properties of an offshore wind turbine at the ice action point, as well as virtual wind loading. The experiments showed that all known regimes of ice-induced vibrations develop depending on the magnitude of the ice drift speed. At low speed this is intermittent crushing and at intermediate speeds is ‘frequency lock-in’ in the second global bending mode of the turbine. For high ice speeds continuous brittle crushing was found. A new finding is the development of an interaction regime with a strongly amplified non-harmonic first-mode response of the structure, combined with higher modes after moments of global ice failure. The regime develops between speeds where intermittent crushing and frequency lock-in in the second global bending mode develop. The development of this regime can be related to the specific modal properties of the wind turbine, for which the second and third global bending mode can be easily excited at the ice action point. Preliminary numerical simulations with a phenomenological ice model coupled to a full wind turbine model show that intermittent crushing and the new regime result in the largest bending moments for a large part of the support structure. Frequency lock-in and continuous brittle crushing result in significantly smaller bending moments throughout the structure.     

Study on a new method for installing a monopile and a fully integrated offshore wind turbine structure

This paper presents a preliminary technical feasibility study on a new methodology proposed for installing a monopile-based bottom supported offshore wind turbine structure. The concept is developed to address the problem of “waiting for a suitable weather window” which is commonly faced by the existing installation methods that uses a typical jack-up platform. In the methodology, a floating vessel along with a floatable subsea structure fitted with a hull on the top, hereafter named SSIP (subsea structure for installing a pile), is proposed first to install a monopile. Then the same structure is used to carry an FIUS (fully integrated upper structure) of an offshore wind turbine, which is characterized by a telescopic tower, and install it over the monopile by using an FOP (float-over-pulling) arrangement. Here, the installation methodologies are first briefly described along with the critical load cases associated with them. These load cases are then numerically studied for a significant wave height (H_S) of 2.5 m, and the results are summarized. For installing a fully integrated offshore wind turbine upper structure on a monopile foundation by the FOP method, two installation schemes are presented, and their dynamic characteristics are compared. It is shown that the proposed methodologies have potential to provide installation solutions which can be environmentally more robust compared to the existing method for installing an offshore wind turbine.     

Modified environmental contour method for predicting long-term extreme responses of bottom-fixed offshore wind turbines

Predicting extreme responses is very important in designing a bottom-fixed offshore wind turbines. The commonly used method that account for the variability of the response and the environmental conditions is the full long-term analysis (FLTA), which is accurate but time consuming. It is a direct integration of all the probability distribution of short-term extremes and the environmental conditions. Since the long-term extreme responses are usually governed by very few important environmental conditions, the long-term analysis can be greatly simplified if such conditions are identified. For offshore structures, one simplified method is the environmental contour method (ECM), which uses the short-term extreme probability distribution of important environmental conditions selected on the contour surface with the relevant return periods. However, because of the inherent difference of offshore wind turbines and ordinary offshore structures, especially their non-monotonic behavior of the responses under wind loads, ECM cannot be directly applied because the environmental condition it selects is not close to the actual most important one.The paper presents a modified environmental contour method (MECM) for bottom-fixed offshore wind turbine applications. It can identify the most important environmental condition that governs the long-term extreme. The method is tested on the NREL 5 MW wind turbine supported by a simplified jacket-type support structure. Compared to the results of FLTA, MECM yields accurate results and is shown to be an efficient and reliable method for the prediction of the extreme responses of bottom-fixed offshore wind turbines.     

航行工况下自升式风车安装船强度直接计算研究

自升自航式风车安装船为海洋工程专业特种船舶,在风机运输,安装中有很高的实际利用价值。采用直接计算法,对航行工况下自升自航式风电安装船的总强度进行评估。建立了船体和桩腿的有限元建模,基于三维势流理论对波浪垂直弯矩进行长期预报,得到风车安装船在典型装载工况下的设计波参数,将船舶在设计波中的重力、静水压力、水动压力、惯性力等施加到模型上进行直接强度分析,对航行工况下船体和桩腿的强度进行了校核。本文的计算方法及结果可为自升自航式风车安装船的整体强度评估、船体结构优化提供有效依据,并且对同类工程船的设计开发具有指导意义。