An optimization approach for fairing of ship hull forms

This paper presents a numerical fairing procedure to be used at the preliminary design stage to create high-quality ship hull form geometry. The procedure is based on a variational optimization approach in which a fairness measure related to the surface curvature is the objective function to be minimized subject to a set of geometric constraints to ensure that the final form has the required geometric characteristics. The optimization variables are selected as the control points of a B-spline surface representing the initial hull form. A nonlinear direct search technique is employed to solve the problem. The methodology is applied for typical ship forms to indicate that, provided that the designer can specify appropriate design objectives and geometric constraints, the methodology can produce alternative hull forms with significantly improved fairing characteristics. The choice of the fairness objective function is shown to have a crucial effect on the quality of the hull surface. Highly nonlinear exact fairness functionals yield surfaces of high quality at the expense of high-computerized effort.     

新型深水钻井隔水管悬挂系统设计

南海海域台风频发,对于深水浮式钻井平台,常规避台模式要求回收所有隔水管,但是在深水、超深水海域,这种应对台风的方案有其局限性。据测算,水深超过1 500 m时,台风准备时间(回收所有隔水管、处理井口的作业时间)超过4天,而目前天气预报的水平只能提前4～5天,因此常规避台难度极大,经常会遭遇到还没有起完隔水管,台风已经逼近平台位置的情况,悬挂隔水管成为一种不得不面对的防台避台方案。硬悬挂和软悬挂是目前悬挂隔水管两种常见的模式,由于软悬挂能够补偿和缓解钻井船升沉施加在悬挂隔水管上的动态载荷,因此业内普遍认为软悬挂模式在提高悬挂隔水管对海洋环境的适应能力方面具有一定的优势,但是常规的软悬挂模式作业程序复杂,而且实施过程中存在伸缩节、张力器液缸等相关设备冲程超标的风险。通过对隔水管悬挂状态下横向和轴向的动力响应进行分析,确定了限制隔水管悬挂安全的主要因素,针对隔水管应力超标和转角过大、干涉等风险,设计了一种具有加装扶正器的锥形悬挂短节;针对悬挂隔水管的轴向压缩风险,研制了一种具有补偿功能的隔水管悬挂装置,降低了悬挂隔水管动态载荷产生轴向压缩和动态应力超标的风险。定量评估表明使用新型隔水管悬挂系统,可以将常规的悬挂窗口由不足10年一遇波流环境条件提高到满足100年一遇的波流环境条件,大大提高了悬挂隔水管的安全性。     

Nonlinear meta-models for conceptual seakeeping design of fishing vessels

The scope of this paper is to develop the nonlinear meta-models for seakeeping behaviour, considering the fishing vessels. These models are intended to be inserted either in a multiattribute design selection process or in a comprehensive multiobjective optimization procedure. For this purpose, seakeeping data of fishing vessels in regular head waves are used to develop meta-models of transfer functions of heave, pitch and vertical acceleration by nonlinear analysis. A home-made software considers two databases; the first is composed by the ship dimensions and coefficients of fishing vessels, and the second is their ship motion data obtained by employing a strip-theory calculation. The meta-models are proposed to predict the vertical motion characteristics for given ranges of speed and wave length during the concept design stage. The independent variables are hull size (Δ), main dimensions (L, B, T), and some hydrostatic parameters (C_WP, C_VP, LCB, LCF, etc.). The results estimated by the software show good correspondences with the ones achieved by direct computations. The study provides additional insight on the influence of hull form parameters on seakeeping performance of small vessels having form properties and parametric range corresponding to the investigated vessels.     

The collaboration modelling framework for ship structural design

Within a shipyard, many designers each have their own design objective cooperating in complex design circumstance that a variety of software tools run on different hardware platforms. Different CAD systems are used by different design stages and departments, and the design result is usually delivered on paper drawings. The proliferation of data and the rising number of disparate data systems do not communicate with each other and certainly do not collaborate. Advanced 3D modelling tools are installed in most of progressive shipyards for advantage to improve their productivities. However these 3D models are repetitiously constructed as per the specified design objectives of disparate software tools in various design stages. This paper describes the development of collaboration modelling framework, knowledge-based design support system, to make a web-based data-sharing collaborative environment potentially allowing to facilitate some applications, construct 3D lines rapidly, translate the product data, and further be capable of providing reasonable model configurations for XML type, and sharing the web services from the Internet to comply with shipyards’ specific strategy for each particular case to be designed.     

Hydrodynamic optimization of ship hull forms

An extremely simple CFD tool is used to compare the calm-water drags of a series of hull forms and to define ‘optimized’ monohull ships for which the total (friction+wave) calm-water drag is minimized. The friction drag is estimated using the classical ITTC formula. The wave drag is predicted using the zeroth-order slender-ship approximation. Comparisons of theoretical predictions and experimental measurements for a series of eight hull forms show that—despite the extreme simplicity of the method that is used here to estimate the friction drag and the wave drag—the method is able to rank the drags of a series of hull forms roughly in accordance with experimental measurements. Thus, the method may be used, with appropriate caution, as a practical hull form design and optimization tool. For purposes of illustration, optimized hull forms that have the same displacement and waterplane transverse moment of inertia as the classical Wigley hull, taken as initial hull in the optimization process, are determined for three speeds and for a speed range.     

A conceptual design of an underwater vehicle

The paper presents a conceptual design of an underwater star wars’ system, which will be more difficult to detect by the enemy than a recently proposed ‘surface’ star wars’ system.The paper suggests that for the proposed structures needed for the underwater star wars’ system, the material of construction should be a composite and not a metal, as use of the latter for large deep diving underwater vessels will result in such structures sinking to the bottom of the ocean like stones, due to the fact that they will have no reserve buoyancy. The paper also shows that composites have better sound absorption characteristics, thereby making the underwater structures difficult to detect through sonar equipment. It is proposed that these underwater structures should operate up to a depth of 7.16 miles (11.52 km), as at this depth, all of the oceans’ bottoms can be reached.The author shows that current technology can be used to construct and operate such vessels, but more progress needs to be made with metal matrix and ceramic composites, so that the hulls of underwater missiles and torpedoes can be constructed in these materials.     

Document based knowledge base engineering method for ship basic design

We propose a basic ship design knowledge-model for information storage and retrieval using a knowledge-based engineering (KBE) system and develop a semantic inquiry function that allows users to use the retrieved information immediately. Our aim is to merge the repetitive access and calculating tasks and data such as the principal dimensions required during the basic ship design process into a single database, so that this information remains available for future construction projects. However, the concept of linking a design knowledge base and inference engine requires the combining of ship design information with the KBE system. This research enhances the flexibility, extension, and operation of the inference mechanism of the KBE design methodology through the establishment of a user interface, knowledge base, and inference engine. The design information is managed a document-based approach, which requires the conversion of the original documents into the XML (eXtensible Markup Language) format, and compiles rules for the basic design process. This system uses the KBE method attempts to reduce the double workload of design and modeling at the commencement of a new project with the document-generating integration work.     

A conceptual design of an underwater missile launcher

The paper presents a conceptual design of an underwater missile launcher, which will be more difficult to detect by the enemy than conventional surface missile launchers which are currently being used.The paper suggests that the material of construction should be a composite and not a metal, as use of the latter for a large deep diving underwater vessel will result in such a structure sinking like a stone, due to the fact that it will have no reserve buoyancy. The paper also shows that composites have better sound absorption characteristics, thereby making the underwater structure difficult to detect through sonar equipment. It is proposed that this launcher should operate up to a depth of 5000 m, as at this depth, some 60% of the oceans' bottoms can be reached.The author shows that current technology can be used to construct and operate such a vessel.     

地震作用下的导管架海洋平台结构动力优化设计研究

把导管架海洋平台看作钢框架结构，并把优化方法用于结构的抗震设计中；以结构的总重量最小为优化目标，导管的平均直径和壁厚作为设计变量，考虑强度、刚度和稳定等约束条件。通过渤海BZ28—1油田储油平台为例进行了计算，计算结果表明，此方法对海洋平台的设计具有一定的参考意义。     

Topology optimization design for offshore platform jacket structure

Offshore jacket platform is widely used as production or oil recovering platform in the shallow sea, and is also applied to the offshore wind turbine supporting structure in the recent years. The jacket structures are normally designed to be conservative and bulky according to various design codes. In this work, a structural optimization design method for jacket platform structure has been developed based on topology optimization theory. The topology optimization method is applicable at an early design stage, which can determine the initial structure and force transmission path. The whole design space is chosen as design variables, and the goal is to maximize the structural stiffness. A set of constraints based on multi-criteria design assessment is applied according to standard requirements, which includes stress, deformation, vibration and design variable constraints. The optimization results are compared with the original platform for static performance, dynamic performance and Ultimate Carrying Capacity (UCC). Results show that the optimized structure show a 13.7% reduction in the global mass, 46.31% reduction in the maximum equivalent stress, and large ultimate carrying capacity ability under the same environmental loads. It is demonstrated that the proposed topology optimization method is capable of effectively determining the optimal design of jacket platform structures.     

Seakeeping assessment of fishing vessels in conceptual design stage

The main idea of this paper is to identify functional relations between seakeeping characteristics and hull form parameters of Mediterranean fishing vessels. Multiple regression analysis is used for quantitative assessment through a computer software that is based on the SQL Server Database. The seakeeping attributes under investigation are the transfer functions of heave and pitch motions and of absolute vertical acceleration at stern, while the ship parameters influencing motion dynamics have been classified into two groups: displacement (Δ) and main dimensions (L, B, T), coefficients that define the details of the hull form (C_WP, C_VP, LCB, LCF, etc.).Four multiple regression models having different parameter combinations are here investigated and discussed, giving way to the so-called ‘Simple Model’, ‘Intermediate Model’, ‘Enhanced 1 Model’ and ‘Enhanced 2 Model’. The obtained results are more than satisfactory for seakeeping predictions during the conceptual design stage.     

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。     

基于拓扑优化方法的船体支柱布局优化设计

船体支柱的布局影响到船舶功能性舱室的布置及相应的结构设计,而目前支柱布局多依赖母型船或者工程师设计经验,缺少基于数学优化的技术支撑。变密度的拓扑优化方法可将属于离散变量优化的支柱布局问题转化为连续变量优化问题。通过悬臂梁—支柱结构的算例,验证了该方法用于解决支柱布局优化问题的可行性。针对某型VLCC的支柱—大跨度甲板结构的支柱布局优化问题,根据布置限制条件设定了支柱优化设计域,选择了两种不同的优化目标函数进行支柱的布局优化设计,最后对优化结果进行了对比分析。结果表明,本方法具有较好的可行性,无需过多设计经验即可优化得到结构性能较好的支柱布局方案,可为此类的支柱布局优化设计提供技术支撑。     

Robust path-following of underactuated ships: Theory and experiments on a model ship

A method is proposed to design a new global controller that forces an underactuated ship to follow a reference path under disturbances induced by wave, wind and ocean-current. The controller is designed such that the ship moves on the path with an adjustable forward speed and its total velocity is tangential to the path. The ship under consideration is not actuated in the sway axis, and the mass and damping matrices are not assumed to be diagonal. Nonlinear damping terms are also included to cover both low- and high-speed applications. The new result is facilitated by choosing an appropriate origin of the body-fixed frame, designing a suitable filter of sway velocity, several nonlinear coordinate changes, the backstepping technique, and utilizing the ship dynamic structure. Experimental results on a model ship illustrate the effectiveness of the proposed method.     

Robust source localization in shallow water based on vector optimization

Owing to the multipath effect, the source localization in shallow water has been an area of active interest. However, most methods for source localization in shallow water are sensitive to the assumed model of the underwater environment and have poor robustness against the underwater channel uncertainty, which limit their further application in practical engineering. In this paper, a new method of source localization in shallow water, based on vector optimization concept, is described, which is highly robust against environmental factors affecting the localization, such as the channel depth, the bottom reflection coefficients, and so on. Through constructing the uncertainty set of the source vector errors and extracting the multi-path sound rays from the sea surface and bottom, the proposed method can accurately localize one or more sources in shallow water dominated by multipath propagation. It turns out that the natural formulation of our approach involves minimization of two quadratic functions subject to infinitely many nonconvex quadratic constraints. It shows that this problem (originally intractable) can be reformulated in a convex form as the so-called second-order cone program (SOCP) and solved efficiently by using the well-established interior point method, such as the software tool, SeDuMi. Computer simulations show better performance of the proposed method as compared with existing algorithms and establish a theoretical foundation for the practical engineering application.     

我国战略石油储备船概念设计研究

阐述了建立我国战略石油储备的必要性，对国外石油储备状况及储备方式做了简要介绍。从我国国情出发，提出了80万m^3浮式钢结构储油船方案设计，建立了储油船整船有限元模型，利用全船三维有限元结构分析技术进行了油舱的分舱设计，供超大型储油船设计时参考。     

渔业资源调查采样设计优化研究进展

渔业资源调查是指利用一定的采样设计,对渔业种群进行空间布点采样,以获取研究区域内鱼类时空分布以及生物学和生态学信息。但是大量的研究表明,不同的鱼类分布适合不同的采样设计,需要根据鱼类的分布特点和调查目标(种群丰度等)优化采样设计,保证数据的准确性和精度。近年来,相关的研究有很多,涉及不同采样设计的比较和应用以及影响数据质量因素的探究。作者着重介绍了定点采样、传统方法、适应性方法和基于地理统计学方法,叙述了计算机模拟及重采样技术在采样设计优化中的应用以及相对偏差、相对估计误差、设计效果和变异系数等评价采样设计性能的指标,同时对采样设计中需要注意的问题进行介绍,最后进行了总结并对未来的研究工作进行展望。     

超大型海洋浮式结构物概念设计的关键技术问题

应用超大型海洋浮式结构物进行海洋空间利用和海洋资源开发，是目前海洋工程界的研究热点。概念设计是超大型海洋浮式结构物研究的基础。本文从设计准则、结构型式、建造材料、模块连接器、系泊系统等几个方面对概念设计的关键技术问题作了归纳，对超大型海洋浮式结构物的概念设计有一定的参考价值。     

集装箱船货舱区结构设计和强度评估研究

基于NAPA Steel软件,实现某集装箱船货舱区的3D结构设计,并输出2D的CAD图纸.同时,在结构设计模型的基础上直接生成三舱段结构的初始有限元模型,参照CCS规范要求对模型进行修改完善后,应用MSC.Nastran软件对其进行了强度分析和屈曲计算,获得了该舱段结构强度的详细信息,并根据评估结果来完善结构设计.与传统的2D结构设计模式相比较,3D结构设计方法能有效地提高设计质量和效率.