基于进化算法的浮筒配置优化问题的研究

根据浮筒配置方案的设计要求和合理性检验准则,给出了方案的优化模型。针对问题的复杂性,结合约束支配的概念,提出了一种改进的将浮筒纵向位置配置和浮筒充气量综合考虑、一体优化多目标进化算法。通过算例分析可知,将多目标进化算法以及约束支配的概念应用到浮筒配置优化方案是可行的、有效的。     

双浮筒直驱式波浪发电系统的优化控制

针对双浮筒直驱式波浪发电系统的工作效率较低问题,提出了一种基于PID(Proportional Integral Derivative)控制的系统优化方法。首先根据波浪力学理论,计算出了双浮筒直驱式波浪发电系统的外浮筒(动浮筒)在自然条件下的运行特性,计算结果表明,受到波浪频率、垂直波浪速度和波浪周期固有特性的影响,外浮筒的垂直运动速度不能与波浪的垂直运动速度达到共振,进而也就导致波浪能转换成电能的工作效率较低。当采用基于PID控制算法对该波浪发电系统进行优化控制之后,波浪能转换成电能的效率有了很大的提高。详尽的算例分析和仿真结果表明本文提出的优化控制方法有效、可行。     

不同构型的超大型浮式结构物水动力分析和波浪载荷预报

超大型浮式结构物是一种新型海上结构,浮体结构的不同构型对水动力性能有着较大的影响,而合理可靠地预报波浪载荷是保证海洋结构物设计合理和安全运营的基本前提。基于设计波法,采用莫里森公式和势流理论相结合的方法,对纵向浮筒和横向浮筒两种不同构型的超大型浮式结构物进行水动力分析和波浪载荷长期预报并进行对比分析。研究结果表明:横向浮筒超大型浮体纵荡运动相应幅值比纵向浮筒超大型浮体小很多;纵向扭转为纵向浮筒和横向浮筒超大型浮体最危险工况,其次是垂向弯矩工况;且横向浮筒超大型浮体的垂向弯矩也是较危险的工况。分析结果可为超大型海上浮式结构物的结构设计提供相关合理可靠的理论依据。     

智能优化方法与粒子滤波技术融合的分析与展望

智能优化算法通过模拟自然生态系统机制以解决复杂优化问题,粒子滤波成为解决非线性及非高斯动态系统最优估计问题的研究热点。若将多种优化算法结合使用,设计更好的滤波器参数寻优步骤,将会极大改善现有非线性滤波的估计性能。介绍了几种智能计算方法和粒子滤波方法,在此基础上,对智能优化方法与粒子滤波技术的融合进行了分析和讨论,并加以总结和展望。     

三分量磁通门传感器校正的循环优化算法

由于制造工艺的原因,三分量磁通门传感器存在固有的零位误差、标度误差和正交误差。介绍了三分量磁通门传感器固有误差的特点,及其数学描述方法。提出了一种循环优化算法,将优化算法引入全部固有误差的校正,采用循环计算的思想提高了解算误差校正参数的准确度。解决了由于测量数据中三种固有误差的同时存在,难于准确求算每种校正参数的问题。应用表明,循环优化算法大大提高了三分量磁通门传感器的校正效果。     

基于遗传算法的缓波型立管多目标集成优化

缓波型立管由于设计参数较多且优化目标之间相互影响,设计结果具有很大的不确定性。随着代理模型和智能优化算法的发展,针对缓波型立管的优化可以提出更好的解决方案。以提高力学性能和经济效益为优化目标,采用基于Kriging插值模型和NSGA-II算法的多目标优化策略,对考虑顶部浮体影响的深水缓波型立管进行动力响应分析,并开展线型—截面双目标优化集成设计和线型—浮筒三目标优化集成设计。将处于不同几何尺度的设计变量进行集成,旨在各目标存在相互竞争的情况下,与截面、浮筒设计形成有效互动以提高线型设计的总体性能。结果表明,Pareto最优解集可提供多个选择方案,以满足工程实际需要。将所选最优方案与初始设计进行对比,并以疲劳性能和成本估算作为优化的校核指标,取得了理想的优化效果。     

多锚链系泊浮筒非线性漂移运动的时域模拟

本文对多锚链系泊浮筒漂移运动的非线性效应进行了讨论。在波浪力和锚链系泊力都是非线性的条件下,对浮筒的运动作时域模拟,并把计算单个系泊锚链流体动力作用的Koterayama W.方法推广到多系泊锚链的情形。计算了规则波和波群中系泊浮筒漂移运动的时间历程,讨论了其运动与波高、频差的关系。可以指出,系泊浮筒系统总漂移运动受锚链流体动力的影响很大;在波群中,其幅值主要受波高支配,与频差的关系较小。     

基于可靠度深海浮式平台加筋板优化设计方法

加筋板是深海浮式平台的主要组成部分,其设计的合理性直接关系到平台整体经济性和安全性,提出一种基于可靠度的加筋板优化设计方法。首先,分析深海浮式平台加筋板的失效模式,得到其极限状态方程,以此为基础采用验算点法计算可靠度指标值,将该可靠度指标值作为结构优化设计的控制参数,得到加筋板的优化设计数学模型。然后,根据可靠度指标值在标准正态空间中的几何意义,推导出其对基本随机变量灵敏度分析的计算表达式,以之作为导数信息,构建出寻找设计最优点的迭代计算公式。以某张力腿平台浮筒部分某加筋板为例,用该算法对其进行基于可靠度的优化设计。计算结果表明,与传统约束优化方法相比,该算法在计算效率和收敛性上具有明显优势。     

HX—20便携式计算机海洋站实用程序

1引言鉴于目前海洋局所属台站已普及使用HX-20计算机(海洋站水文、气象观测资料处理程序由《海洋站微机配置》课题组已设计成功,并使用运行),笔者结合海洋站测报工作中的一些具体问题,特给出了日常业务所需常备表格制作的HX-20计算机的5个计算程序。即:(1)测波浮筒的水平距离和方位的允许变化范围的计算。(2)波高测量中浮筒跳动平均位置的计算。(3)各种温度表器差订正值的计算。(4)SYY1-1型光学折射盐度计温度修正值的计算。     

变分同化研究中最速下降算法的一个改进

对于变分同化中经常遇到的多极值问题，一般的优化算法无法解决。以最速下降算法为例，提出一种改进方法，在迭代到某个极值点时，自动跳出该极值点附近去寻找下一个极值点，直到找到满意的最小值点为止。原则上这种改进算法可推广应用到其它优化算法中。     

Optimization of variational methods

Lord Rayleigh proposed his now classical method (based on a one-term deflection function) in 1870. On the other hand, he suggested in 1894 the possibility of optimizing the eigenvalues (natural frequencies or buckling loads) by minimizing them with respect to an exponential parameter contained in the coordinate function. This optimization approach has become increasingly popular in the last decade and it has been extended to other variational methods and bounding techniques. The present paper reviews recent developments in this area which consists, essentially, in a nonlinear optimization process of the coordinate functions in a global sense. The technique is applicable in a large variety of applied mechanics problems of considerable interest to ocean engineers dealing with the analysis of mechanical systems.     

一种新型混沌遗传优化算法的研究

在对遗传算法交叉、变异后结果的处理方法进行改进并在将进化过程分段的基础上,提出1种新的混沌遗传算法。该算法利用混沌运动的遍历性择优产生初始群体,对每一轮遗传操作所得到的部分当前最优个体进行变尺度混沌搜索。仿真结果表明,该算法具有较高的优化效率,并能求得全局最优解。     

屈曲利用因子约束下船体板架结构优化设计方法

船体板架结构在屈曲约束下的优化问题具有变量多和约束多的特点,且屈曲计算需借助有限元分析,属于大规模耗时优化问题,运用常规优化方法求解需要较高的计算成本。这里提出一种适用于屈曲约束下船体板架快速优化方法,该方法利用板格屈曲利用因子具有局部性的特点,对板格厚度自变量空间进行降维处理;利用板格屈曲利用因子对板格厚度具有单调性的特点,采用牛顿迭代方法求解其达到目标值的板格厚度;同时比较板格在相同重量增量下,加筋叠加板厚与仅加板厚对屈曲利用因子改善程度的大小决定是否加筋;通过两阶段的迭代寻优,快速获得最优的板厚以及防屈曲筋布置方案。某油船双层底优化结果显示,该方法能够在30步之内完成优化计算,优化效率高;优化方案相比原始方案减重达17.63%,绝大部分板格屈曲利用因子取值在0.9～1.0之间,材料得到充分利用。     

载人潜水器圆柱形耐压壳体的优化设计研究

采用分枝定界法和序列二次规划方法,对载人潜水器圆柱形耐压壳体的重量最小化进行了研究.设计变量是壳板的厚度、肋骨的型号、间距和数量,讨论了下潜深度、材料几何参数对重量以及其它特征量的影响.算例计算表明,下潜深度越大,屈服极限越高的材料重量减轻越明显.对于大深度而言,选用高屈服极限材料,可以使得材料能够充分利用.文中还对结构重量占排水量比例随深度变化的情况进行了研究.     

Fuzzy Optimum Model of Semi-Structural Decision for Lectotype Optimization of Offshore Platforms

In the process of concept design of offshore platforms, it is necessary to select the best from feasible alternatives through comparison and filter. The criterion set, used to evaluate and select the satisfying alternative, consists of many qualitative and quantitative factors. Therefore, the selection is a problem of multicriteria and semi- structural decision- making. Different from traditional methods in semi- structural decision- making, a new framework and methodology is presented in this paper for evaluation of offshore platform alternatives. First, the criterion set is established for the evaluation of alternatives. Next, the approach is studied to construct the relative membership degree matrix, in which both qualitative and quantitative factors are consistent with the uniform calculating standard. And then a new weight-assessing method is developed for calculation of the weights based on the relative membership degree matrix. Finally, a multi-hierarchy fuzzy optimum model is adopted to select t     

海洋平台抛锚方式模糊优化设计方法

海上钻井平台由于工作地点经常发生变化,工作环境条件随之改变,锚泊抛锚方式就要相应更改。本文针对深海半潜平台及其悬链线式系泊定位系统,运用平台与锚链耦合运动时域分析方法,对其水动力性能进行探索,并提出一种运用模糊算法计算平台抛锚方式优化设计方法,此方法可使钻井平台在风暴自存工况和钻井工作工况下更快更好地找到最佳抛锚方式。以一典型的半潜式钻井平台为例进行数值模拟,结果表明本文提出的方法是可行的,能够很方便地找到比较好的抛锚方式来满足相关要求。这种锚泊优化设计方法可为平台及其系泊系统设计提供参考。     

一类全局最优化问题的动态隧道方法

研究了连续变量函数的全局最优化问题 ,给出了动态隧道方法。该动态隧道方法由局部搜索和动态隧道 2个阶段构成。在局部搜索阶段用了动态系统方法。对全局最优化问题的实例进行了数值实验 ,数值结果表明了该方法的稳健性和有效性。     

Enhanced Multi-Layer Fatigue-Analysis Approach for Unbonded Flexible Risers

This paper proposes an enhanced approach for evaluating the fatigue life of each metallic layer of unbonded flexible risers. Owing to the complex structure of unbonded flexible risers and the nonlinearity of the system, particularly in the critical touchdown zone, the traditional method is insufficient for accurately evaluating the fatigue life of these risers. The main challenge lies in the transposition from global to local analyses, which is a key stage for the fatigue analysis of flexible pipes owing to their complex structure. The new enhanced approach derives a multi-layer stress-decomposition method to meet this challenge. In this study, a numerical model validated experimentally is used to demonstrate the accuracy of the stress-decomposition method. And a numerical case is studied to validate the proposed approach. The results demonstrate that the multi-layer stress-decomposition method is accurate, and the fatigue lives of the metallic layers predicted by the enhanced multi-layer analysis approach are rational. The proposed fatigue-analysis approach provides a practical and reasonable method for predicting fatigue life in the design of unbonded flexible risers.     

Enhanced multi-layer fatigue-analysis approach for unbonded flexible risers

This paper proposes an enhanced approach for evaluating the fatigue life of each metallic layer of unbonded flexible risers. Owing to the complex structure of unbonded flexible risers and the nonlinearity of the system, particularly in the critical touchdown zone, the traditional method is insufficient for accurately evaluating the fatigue life of these risers. The main challenge lies in the transposition from global to local analyses, which is a key stage for the fatigue analysis of flexible pipes owing to their complex structure. The new enhanced approach derives a multi-layer stress-decomposition method to meet this challenge. In this study, a numerical model validated experimentally is used to demonstrate the accuracy of the stress-decomposition method. And a numerical case is studied to validate the proposed approach. The results demonstrate that the multi-layer stress-decomposition method is accurate, and the fatigue lives of the metallic layers predicted by the enhanced multi-layer analysis approach are rational. The proposed fatigue-analysis approach provides a practical and reasonable method for predicting fatigue life in the design of unbonded flexible risers.     

Bathymetry Data Correction Using Global Optimization Method

The bathymetry data of marine bodies have been collected over a century, and the collected data have a wide range of resolution and accuracy. Acquisition of bathymetry data is very costly and time-consuming. One can use the old, low-quality bathymetry data to fill the gap in high-quality, recently acquired bathymetry data after correcting the old data to improve its quality so that it is comparable to the high-quality data. The old data correction can be treated as a nonlinear inverse problem. Simulated annealing (SA) global optimization method was used here in solving this problem. The two sets of data that were used are project survey (PS) and Vietnamese Navy Chart (VNC) data. The PS data were collected in 2000 in an offshore survey from the Vietnam coast in the South China Sea (SCS). The VNC data were obtained by digitizing VNC that was published in 1981. Inverse distance weighted (IDW) interpolation method was used for forward modeling. Weperformed the SA algorithm run starting at a high "temperature," then lowering the "temperature" gradually up to the "critical temperature" and then staying there for the rest of the run. The best model chosen by the algorithm showed an improvement of 63% from the original model. We then constructed a digital bathymetry model (DBM) of the study area with the combined corrected VNC and the PS data.