Controllable pitch propeller optimization through meta-heuristic algorithm

This paper describes a methodology to design and optimize a controllable pitch propeller suitable for small leisure ship boats. A proper range for design parameters has to be set by the user. An optimization based on the Particle Swarm Optimization algorithm is carried out to minimize a fitness function representing the engine’s fuel consumption. The OpenProp code has been integrated in the procedure to compute thrust and torque. Blade’s geometry and tables about pitch, thrust and consumption are the main output of the optimization process. A case study has been included to show how the procedure can be implemented in the design process. A case study shows that the procedure allows a designer to sketch a controllable pitch propeller with optimal efficiency; computational times are compatible with the design conceptual phase where several scenarios must be investigated to set the most suitable for the following detailed design. A drawback of this approach is given by the need for a quite skilled user in charge of defining the allowable ranges for design parameters, and the need for data about the engine and boat to be designed.

     

船舶调距桨微机控制系统的实时混合仿真

本文介绍了一种用于船舶调距桨的微型计算机控制系统.为进行系统的硬软件联调和控 制参数预整定,本文建立了调距桨自动控制系统各主要单元的仿真数学模型,并设计了调距桨 微机控制实时混合仿真系统.实验证明,本微机控制系统的设计和合理可行的.     

Dynamic positioning of drilling vessels with a fuzzy logic controller

A fuzzy logic controller for dynamic positioning of drilling vessels in deep water is presented. The core of the fuzzy controller is a set of fuzzy associative memory (FAM) rules that correlate each group of fuzzy control input sets to a fuzzy control output set. A FAM rule is a logical if-then-type statement based on one's sense of realism and experience or can be provided by an expert operator. The design of the fuzzy controller is very simple and does not require mathematical modelling of the complicated nonlinear system based on first principles. The fuzzy controller uses measured vessel heading, yaw rate, distance and velocity of the vessel relative to the desired position (location and heading) to generate the control outputs to bring the vessel to and maintain it in the desired position. The control outputs include the rudder angle, propeller thrust and lateral bow thrust. The effectiveness and robustness of the fuzzy controller are demonstrated through numerical time-domain simulations of the dynamic positioning of a drill ship of Mariner Class hull with use of nonlinear ship equations of motions.     

Interactive computer programme to facilitate diesel engine/propeller matching

The general problem of matching a diesel engine to a propeller is solved using a computer programme. The programme can deal with any engine specified by constraints on its power speed characteristic readily available from manufacturers, and any hull form provided resistance vs speed curves are available either from scale model experiments, standard curves or sea trials. For any selected propeller diameter, gear ratio or propeller blade area ratio the programme automatically calculates the maximum ship speed which just satisfies the engine constraints over a range of propeller pitch ratio values. The calculation is based on using a data bank of previously. stored model series thrust and torque parameters, and the resulting forward speed vs pitch ratio curve is presented on a graphics terminal. Families of these characteristics can be automatically generated for selected variations in propeller diameter, blade area ratio, gear ratio or for different resistance vs speed curves which may represent other ship displacements, trims or account for fouling, weather, etc. The display curves are stored and may be interactively retrieved under light pen control so that rapid comparisons can easily be drawn between different parameter selections.As an example of the use of the programme the paper describes the design of a propulsion system for a small commercial vessel using hypothetical data, and thus demonstrates the sensitivity of speed vs pitch ratio characteristic variations with propeller diameter, gear ratio, blade area ratio and displacement, and some general conclusions may be drawn from the results presented.     

基于骨架模型的船体结构快速建模

针对当前我国船舶结构设计中迭代次数多、设计存在异地性的问题,提出一种船 体结构快速建模方法。以“自顶向下”为设计思路,以骨架模型为实现载体,对船体结构特点进 行分析、总结后构建了面向船舶结构的骨架模型,给出船体结构骨架模型的定义。通过船舶结 构的骨架模型与参数坐标系实现船舶总体的快速布局设计;建立参数坐标系与船体板架之间的 关联关系实现船体结构的快速建模与快速调整,并给出相应算法;给出设计信息的组织方式并 将设计信息集成到骨架模型实现船体结构模型的完整性定义与快速建立。最后基于 CATIA V6 平台开发快速建模系统,并通过纵骨架式船体结构验证了方法的可行性。     

Three-dimensional Visual Mapping of Underwater Ship Hull Surface Using Piecewise-planar SLAM

In-water visual ship hull inspection using unmanned underwater vehicles needs to be performed at very close range to the target surface because of the visibility limitations in underwater environments mainly due to light attenuation, scattering, and water turbidity. These environmental challenges result in ineffective photometric and geometric information in hull surface images and, therefore, the performance of conventional three-dimensional (3D) reconstruction techniques is often unsatisfactory. This paper addresses a visual mapping method for 3D reconstruction of underwater ship hull surface using a monocular camera as a primary mapping sensor. The main idea of the proposed approach is to model the moderately curved hull surface as a combination of piecewise-planar panels, and to generate a global map by aligning the local images in a two-dimensional reference frame and correcting them appropriately to reflect the information of perspective projections of the 3D panels. The estimated 3D panels associated with the local images are used to extract the loop-closure relative measurements in the framework of simultaneous localization and mapping (SLAM) for precise camera trajectory estimation and 3D reconstruction results. The validity and practical feasibility of the proposed method are demonstrated using a dataset obtained in a field experiment with a full-scale ship in a real sea environment.

     

Federated learning for green shipping optimization and management

Many shipping companies are unwilling to share their raw data because of data privacy concerns. However, certain problems in the maritime industry become much more solvable or manageable if data are shared—for instance, the problem of reducing ship fuel consumption and thus emissions. In this study, we develop a two-stage method based on federated learning (FL) and optimization techniques to predict ship fuel consumption and optimize ship sailing speed. Because FL only requires parameters rather than raw data to be shared during model training, it can achieve both information sharing and data privacy protection. Our experiments show that FL develops a more accurate ship fuel consumption prediction model in the first stage and thus helps obtain the optimal ship sailing speed setting in the second stage. The proposed two-stage method can reduce ship fuel consumption by 2.5%–7.5% compared to models using the initial individual data. Moreover, our proposed FL framework protects the data privacy of shipping companies while facilitating the sharing of information among shipping companies.     

Delay-discretization-based sliding mode $$H_{\infty }$$ load frequency control scheme considering actuator saturation of wind-integrated power system

This paper investigates the combined effect of actuator saturation and time-delay on load frequency control (LFC) of a wind-integrated power system (WIPS). Actuator saturation is represented in two different approaches such as polytopic and sector bounding. Delay-discretization-based sliding mode \(H_{\infty }\) control approach is proposed to design a novel LFC scheme. The proposed control scheme requires present as well as delayed states information as input to the controller. This requirement of control scheme is fulfilled by adopting a finite known delay. This finite known delay used in controller design is discretized into delay intervals. Lyapunov–Krasovskii functional is defined for each delay interval, and \(H_{\infty }\) stabilization criteria for the closed loop WIPS are derived in linear matrix inequality framework using Wirtinger-based inequality. The proposed control scheme is tested by considering a numerical example of two-area WIPS.

     

基于CFD近似模型的船尾线型多目标综合优化

为提高船体的优化效率,以国际标准船型KCS为研究对象,以船舶总阻力和桨盘面伴流不均匀度为优化目标,建立近似模型,完成KCS船尾线型的优化,得到优化船型．通过优化结果可知：对于母型船,在满足工程约束条件下,通过船尾优化可以得到总阻力未增加、船尾流场品质有明显改善的船体线型．     

A study on the preliminary ship design method using deterministic approach and probabilistic approach including hull form

This paper describes a preliminary ship design method using deterministic approach and probabilistic approach in the process of hull form design. In the deterministic approach, an interdisciplinary ship design method integrates principal dimension decisions and hull form variations in the preliminary ship design stage. Integrated ship design, as presented in this paper, has the distinctive feature that these parameters are evaluated simultaneously. Conversely, in sequential design, which is based on the traditional preliminary ship design process, hull form designs and principal dimension decisions are determined separately and sequentially. The current study adopts the first method to enhance the design quality in the early design stage. Furthermore, a probabilistic approach is applied to ship design to resolve uncertainties in design information more efficiently than a deterministic approach would.     

Development of a simple model for batch and boundary information updation for a similar ship’s block model

In early 2000,large domestic shipyards introduced shipbuilding 3D computer-aided design (CAD) to the hull production design process to define manufacturing and assembly information.The production design process accounts for most of the man-hours (M/H) of the entire design process and is closely connected to yard production because designs must take into account the production schedule of the shipyard,the current state of the dock needed to mount the ship’s block,and supply information.Therefore,many shipyards are investigating the complete automation of the production design process to reduce the M/H for designers.However,these problems are still currently unresolved,and a clear direction is needed for research on the automatic design base of manufacturing rules,batches reflecting changed building specifications,batch updates of boundary information for hull members,and management of the hull model change history to automate the production design process.In this study,a process was developed to aid production design engineers in designing a new ship’s hull block model from that of a similar ship previously built,based on AVEVA Marine.An automation system that uses the similar ship’s hull block model is proposed to reduce M/H and human errors by the production design engineer.First,scheme files holding important information were constructed in a database to automatically update hull block model modifications.Second,for batch updates,the database’s table,including building specifications and the referential integrity of a relational database were compared.In particular,this study focused on reflecting the frequent modification of building specifications and regeneration of boundary information of the adjacent panel due to changes in a specific panel.Third,the rollback function is proposed in which the database (DB) is used to return to the previously designed panels.     

Improvement of ship design practice using a 3D CAD model of a hull structure

At the initial stage of ship design, a hull structural model, that is, a 3D CAD model of a hull structure is not generated by the existing shipbuilding CAD system because it is time-consuming and requires much effort. Without the hull structural model, a designer must manually calculate the production material information of a building block by using 2D drawings, parent ship data, and design experiences at the initial planning and scheduling stages. At the initial stage of hull structural analysis, the designer manually generates a structural analysis model, that is, a finite element model of the hull structure. Moreover, the piping model, that is a 3D CAD model of the pipes in the hull structure, is generated independently of the hull structural model at the detailed design stage. To lighten the burden imposed on the designer, we developed an initial hull structural modeling system in our previous study. Using this system, a designer can rapidly and easily generate the hull structural model at the initial stage of design. In this study, the generation methods of the production material information of a building block, the structural analysis model, and the piping model based on the hull structural model are developed. The applicability of the developed methods are demonstrated by applying them to a deadweight 300,000 ton very large crude oil carrier (VLCC). The results show that the developed methods can quickly generate the corresponding information or models at the initial design stage.     

An artificial neural network based decision support system for energy efficient ship operations

Reducing fuel consumption of ships against volatile fuel prices and greenhouse gas emissions resulted from international shipping are the challenges that the industry faces today. The potential for fuel savings is possible for new builds, as well as for existing ships through increased energy efficiency measures; technical and operational respectively. The limitations of implementing technical measures increase the potential of operational measures for energy efficient ship operations. Ship owners and operators need to rationalise their energy use and produce energy efficient solutions. Reducing the speed of the ship is the most efficient method in terms of fuel economy and environmental impact. The aim of this paper is twofold: (i) predict ship fuel consumption for various operational conditions through an inexact method, Artificial Neural Network ANN; (ii) develop a decision support system (DSS) employing ANN-based fuel prediction model to be used on-board ships on a real time basis for energy efficient ship operations. The fuel prediction model uses operating data – ‘Noon Data’ – which provides information on a ship’s daily fuel consumption. The parameters considered for fuel prediction are ship speed, revolutions per minute (RPM), mean draft, trim, cargo quantity on board, wind and sea effects, in which output data of ANN is fuel consumption. The performance of the ANN is compared with multiple regression analysis (MR), a widely used surface fitting method, and its superiority is confirmed. The developed DSS is exemplified with two scenarios, and it can be concluded that it has a promising potential to provide strategic approach when ship operators have to make their decisions at an operational level considering both the economic and environmental aspects.     

计及螺旋桨负载的船舶电力系统协调控制设计

推进负载对船舶电网的暂态稳定性影响是船电系统的主要特征之一.本文基于非线性鲁棒L2干扰抑制控制方法,研究了具有螺旋桨负荷的船舶电力系统中的励磁与调速的协调控制问题,在充分分析了柴油发电机组的非线性数学模型及其螺旋桨负载的相互耦合的非线性动态结构特性的基础上,提出backstepping控制技术与L2干扰抑制相结合的综合协调控制策略来设计控制器.该控制器在保证系统稳定的条件下,有效地抑制干扰对发电机系统电压和频率的影响.仿真表明,在给系统突加螺旋桨负载的情况下,该控制器能有效地抑制负载对系统性能的影响,验证了控制器的有效性.     

Rapid generation of the piping model having the relationship with a hull structure in shipbuilding

At the initial stage of ship design, a hull structural model, that is, 3D CAD model of a hull structure is not generated by the existing shipbuilding CAD system because it is time-consuming and requires much effort. As a result, a designer is generating a piping model, that is, 3D CAD model of the pipes in the hull structure, independently of the hull structural model at the detailed design stage. The designer must manually modify the piping model whenever the hull structural model changes. To lighten the burden imposed on the designer, a generation method of the piping model based on the hull structural model is developed in this study. The applicability of the developed method is demonstrated by applying it to a deadweight 300,000 ton VLCC (Very Large Crude Oil Carrier). The result shows that the developed method can quickly generate the piping model having the relationship with the hull structure in early time.     

船舶运动视景仿真系统设计与实现

针对研究船舶各种运动状态,为有效验证控制器的功能提供有效平台。采用船舶运动可视化,对视景仿真系统进行开发,对各种常见的建模和驱动技术进行了重点研究。提出了船舶运动视景仿真系统的整体设计方案及流程,利用建模软件Creator建立了逼真的三维船舶实体模型,采用DOF节点技术建立了舵\翼舵、鳍\翼鳍及螺旋桨的活动模型;解决了视景仿真系统开发中的视点切换、多通道显示、仿真数据加载等关键问题;基于VC++集成开发环境和Vega API编程技术开发了系统。三维仿真结果表明系统具有较好交互性和逼真度,为船舶运动特性研究提供了可靠手段。     

船舶产品设计(SPD)系统

为打破国外船舶设计系统对我国船舶设计的垄断,提高我国船舶设计、建造的创新能力,开发具有我国自主知识产权的船舶产品设计(Shipping Product Design, SPD)系统. 该系统基于OpenGL开发具有自主知识产权的三维CAD图形平台,具有船体结构设计、管系设计、风管设计、电气设计、铁舾件设计和涂装生产设计等功能. SPD系统具有如下特点:能保持三维模型与二维图纸的高度一致;通过生成完整的加工制造信息实现CAD/CAPP/CAM集成,基本打通"壳、舾、涂一体化"的数字化生产线;通过生成壳、舾、涂完整的制造和管理信息,为实现船舶"设计、制造、管理一体化"奠定基础;通过实体和参数化技术为建立具有完整拓扑关系的船舶产品模型提供有力手段;并通过与其他系统的数据接口实现异构CAD的数据和信息集成,为厂、所协同设计创造技术条件等. SPD系统推广应用表明它有助于现代造船模式的推进和数字化造船目标的实现.     

A study on bunker fuel management for the shipping liner services

In this paper, we consider a bunker fuel management strategy study for a single shipping liner service. The bunker fuel management strategy includes three components: bunkering ports selection (where to bunker), bunkering amounts determination (how much to bunker) and ship speeds adjustment (how to adjust the ship speeds along the service route). As these three components are interrelated, it is necessary to optimize them jointly in order to obtain an optimal bunker fuel management strategy for a single shipping liner service. As an appropriate model representing the relationship between bunker fuel consumption rate and ship speed is important in the bunker fuel management strategy, we first study in detail this empirical relationship. We find that the relationship can be different for different sizes of containerships and provide an empirical model to express this relationship for different sizes of containerships based on real data obtained from a shipping company. We further highlight the importance of using the appropriate consumption rate model in the bunker fuel management strategy as using a wrong or aggregated model can result in inferior or suboptimal strategies. We then develop a planning level model to determine the optimal bunker fuel management strategy, i.e. optimal bunkering ports, bunkering amounts and ship speeds, so as to minimize total bunker fuel related cost for a single shipping liner service. Based on the optimization model, we study the effects of port arrival time windows, bunker fuel prices, ship bunker fuel capacity and skipping port options on the bunker fuel management strategy of a single shipping liner service. We finally provide some insights obtained from two case studies.     

中国船级社共同结构规范计算软件CSR-SDP

为提高船舶设计效率,针对国际船级社协会(International Association of Classification Societies, IACS)2006年推出的散货船、双壳油船共同结构规范CSR-BC/OT,中国船级社(China Classification Society, CCS)开发出计算软件CSR-SDP. 该软件分为针对散货船的CSR-SDP(BC)和针对双壳油船的CSR-SDP(OT)两套,是集规范设计,载荷计算以及船体结构强度分析、评估和疲劳寿命评估于一体的船体结构设计和规范校核系统,较全面地覆盖CSR-BC/OT的要求,较好地满足CSR船舶设计和审图的需要.     

An initial hull structural modeling system for computer-aided process planning in shipbuilding

At the initial stage of ship design, it is difficult for designers to define all design information of a hull structure on 2D drawings. Thus, other designers must undertake the arduous task of translating such information to generate a 3D CAD model of the hull structure which is required at the following design stage such as the initial process planning stage. Since this task needs much time and effort, the 3D CAD model is not being generated at the initial design stage. For solving this problem, an initial hull structural modeling system is developed in this study. The applicability of the developed system is demonstrated by applying it to a deadweight 300,000 ton VLCC (Very Large Crude oil Carrier). The results show that the developed system can quickly generate the 3D CAD model of the hull structure and accurately extract the production material information for computer-aided process planning at the initial design stage.