波浪作用下小尺度多船并排锚泊横摇运动试验研究

采用物理模型试验方法研究双船、三船和四船并排锚泊时各船的运动量,并与单船艏艉锚泊情况进行了对比,重点分析了横浪作用下各船的横摇运动规律,探究了波浪周期和并排锚泊船数对多船并排锚泊时横摇运动的影响。结果表明,多船并排锚泊时,横摇运动响应随着波浪周期的增大而逐渐减小。双船并排锚泊时,横摇运动响应同单船相比减少了40%~50%;三船和四船并排锚泊时,横摇运动响应同单船相比减少50%~60%,四船并排锚泊时横摇运动响应减小的幅度与三船并排时相比差别不大。

基于数学建模方法的旅游船只行程安排探究

针对旅行船数最大问题，首先考虑“旅行船接触最小”因素，建立了单线通航模型；其次考虑“船数最多并充分利用营地”因素，利用0-1规划方法建立多线通航、船只最多模型；最后综合三个因素，建立多目标函数整数规划模型。对比三个模型，算出营地数为60时，多目标函数整数规划模型可得到最大旅游次数，为每年1＆#8198;080次，并在此基础上制定了最佳行程时间表。

舰艇数字样船技术及其平台体系结构研究

根据舰艇研制的特点,结合数字样船技术在舰艇设计、制造、维修、保障、训练直到退役等全过程中的应用需求,文章对数字样船技术的内涵、数字样船模型的层次划分、多层次数字样船模型的组成及其体系结构进行了认真的分析和研究,并在此基础上提出了舰艇多层次数字样船模型的组成、体系结构和需要突破的主要关键技术,为深入开展舰艇数字样船技术研究和平台的建立奠定了基础.

基于全三维数字样船的船舶产品信息集成应用研究

数字样机技术已在航空、航天、汽车工业等行业的研制过程中得到广泛应用。由于船舶产品的复杂性和特殊性,基于全三维设计的数字样船技术应用程度相对落后。从数字样机概念与特征入手,结合船舶研制特点,提出了全三维数字样船的概念,对全三维数字样船的特征进行概要描述,分析了基于全三维数字样船的数字化造船技术体系。在此基础上,从国内外数字化造船发展趋势入手,结合船舶产品三维设计、数据管理、生产管理、设计仿真与虚拟建造、精度测量与控制等方面业务需求和信息集成要求,提出了基于全三维数字样船的船舶产品信息集成与应用实施总体解决方案。基于此方案,在液化天然气船进行了应用验证,为实现船舶产品研制体系的转变提供了应用示范。

舰船虚拟设计研究

舰船虚拟设计是近几年来随着虚拟现实技术、产品生命周期管理技术、先进船舶设计技术的发展而兴起的一种船舶设计方法.文章概述了舰船虚拟设计的体系构成、分析了其关键技术、叙述了应用现状并对未来的应用提出了建议.

中国船舶所有权变动规则辨析

《中华人民共和国物权法》第23条关于动产物权变动以交付为生效要件的规定,奠定了债权形式主义在中国动产物权变动模式中的统领地位。尽管船舶等特殊动产采登记对抗主义,仍不能撼动其地位,登记只是其公示方式,交付才是所有权变动的生效要件。《最高人民法院关于审理买卖合同纠纷案件适用法律问题的解释》第10条为多重买卖下,特殊动产所有权的归属问题设定了认定标准。然而部分标准有违基本法理,应予更正。

Research on optimization of valve open time of the launch barge's ballast tanks

Launch barge is an effective tool for transporting ship segments from one place to another in shipyards. During shifting of segments onto a barge, the slideway on the barge＇s deck must be adjusted to maintain the same level as the wharf and also the barge must be kept level by adjusting the water in the ballast tanks. When to open the adjusting valves is an important factor influencing the barge＇s trim during the water-adjustment process. Because these adjustments are complex a mathematical model was formulated,after analyzing the characteristics of the process of moving the segments onto the barges deck, and considering the effects of this movement＇s speed and variations in tidal levels during the move. Then the model was solved by the penalty function method, the grid method, and improved simulated annealing, respectively. The best optimization model and its corresponding solution were then determined. Finally, it was proven that the model and the method adopted are correct and suitable, by calculating and analysing an example.

CFD simulation of propeller and rudder performance when using additional thrust fins

To analyse a possible way to improve the propulsion performance of ships,the unstructured grid and the Reynolds Average Navier-Stokes equations were used to calculate the performance of a propeller and rudder fitted with additional thrust fins in the viscous flow field.The computational fluid dynamics software FLUENT was used to simulate the thrust and torque coefficient as a function of the advance coefficient of propeller and the thrust efficiency of additional thrust fins. The pressure and velocity flow behind the propeller was calculated. The geometrical nodes of the propeller were constituted by FORTRAN program and the NUMBS method was used to create a configuration of the propeller,which was then used by GAMMBIT to generate the calculation model. The thrust efficiency of fins was calculated as a function of the number of additional fins and the attack angles. The results of the calculations agree fairly well with experimental data,which shows that the viscous flow solution we present is useful in simulating the performance of propellers and rudders with additional fins.

Spatiotemporal factors affecting fish harvest and their use in estimating the monthly yield of single otter trawls in Putuo district of Zhoushan, China

We used generalized additive models (GAM) to analyze the relationship between spatiotemporal factors and catch, and to estimate the monthly marine fishery yield of single otter trawls in Putuo district of Zhoushan, China. We used logbooks from five commercial fishing boats and data in government's monthly statistical reports. We developed two GAM models: one included temporal variables (month and hauling time) and spatial variables (longitude and latitude), and another included just two variables, month and the number of fishing boats. Our results suggest that temporal factors explained more of the variability in catch than spatial factors. Furthermore, month explained the majority of variation in catch. Change in spatial distribution of fleet had a temporal component as the boats fished within a relatively small area within the same month, but the area varied among months. The number of boats fishing in each month also explained a large proportion of the variation in catch. Engine power had no effect on catch. The pseudo-coefficients (PCf) of the two GAMs were 0.13 and 0.29 respectively, indicating the both had good fits. The model yielded estimates that were very similar to those in the governmental reports between January to September, with relative estimate errors (REE) of <18%. However, the yields in October and November were significantly underestimated, with REEs of 36% and 27%, respectively.

Application of Numerical Simulation for Analysis of Sinking Characteristics of Purse Seine

This study applies the mass-spring system to model the dynamic behavior of a submerged net panel similar to the shooting process in actual purse seine fishing operation. Modeling indicates that there is insufficient stretching with the net panel under the floatline in the prophase of the shooting process. Sinkers at different locations along the leadline descend successively after submergence, and the sinking speed decreases gradually with elapsed time until attainment of a stable state. Designs with different current speeds and sinker weights are executed to determine the dimensional shape and sinking characteristics of the net. The net rigged with greater sinker weight gains significantly greater sinking depth without water flow. Compared with the vertical spread of the net wall in static water, the middle part of the netting presents a larger displacement along the direction of current under flow condition. It follows that considerable deformation of the netting occurs with higher current speed as the sinkers affected by hydrodynamic force drift in the direction of current. The numerical model is verified by a comparison between simulated results and sea measurements. The calculated values generally coincide with the observed ones, with the former being slightly higher than the latter. This study provides an implicit algorithm which saves computational loads for enormous systems such as purse seines, and ensures the accuracy and stability of numerical solutions in a repetitious iteration process.

Comparative Analysis of the Separation Variation Influence on the Hydrodynamic Performance of a High Speed Trimaran

This paper numerically investigates the influence of separation variation of the outriggers on the hydrodynamic performance of a high speed trimaran （HST） aiming at improving its applicability in diverse realistic disciplines. The present investigation was performed within the framework of the 2-D slender body method （SBM） by calculating the resistance of three symmetric trimaran series moving in a calm free surface of deep water. Each trimaran series comprises of 4681 configurations generated by considering 151 staggers （-50%≤a≤＋ 100%）, and 31 separations （100%≤β≤400%） for 81 Froude numbers （0.20≤Fn≤ 1.0）. In developing the three trimaran series, Wigley-st. AMECRC-09, and NPL-4a models were used separately for both the main and side hulls of each individu;d series models. A computer macro named Tri-PL was created using the Visual Basic for Applications~. Tri-PL~ sequentially interfaced Maxsurfe then Hullspeed to generate the models of the three trimaran series together with their detailed hydrostatic particulars, followed by their resistance components. The numerical results were partially validated against the available published numerical calculations and experimental results, to benchmark the Tri-PL macro and hence to rely on the analysis outcomes. A graph template was creaLed within the framework of SigmaPlot to visualize the significant results of the Tri-PL properlv.

Numerical Study of Viscous Wave-Making Resistance of Ship Navigation in Still Water

The prediction of a ship＇s resistance especially the viscous wave-making resistance is an important issue in CFD applications. In this paper, the resistances of six ships from hull 1 to hull 6 with different hull forms advancing in still water are numerically studied using the solver naoe-FOAM-SJTU, which was developed based on the open source code package OpenFOAM. Different components of the resistances are computed and compared while considering two speed conditions （12 kn and 16 kn）. The resistance of hull 3 is the smallest while that of hull 5 is the largest at the same speed. The results show hull 3 is a good reference for the design of similar ships, which can provide some valuable guidelines for hull form optimization.

Mechanical Behavior of a Glass-fiber Reinforced Composite to Steel Joint for Ships

The use of a glass-fiber reinforced composite in marine structures is becoming more common, particularly due to the potential weight savings. The mechanical response of the joint between a glass-fiber reinforced polymer （GRP） superstructure and a steel hull formed is examined and subsequently modified to improve performance through a combined program of modeling and testing. A finite-element model is developed to predict the response of the joint. The model takes into account the contact at the interface between different materials, progressive damage, large deformation theory, and a non-linear stress-strain relationship. To predict the progressive failure, the analysis combines Hashin failure criteria and maximum stress failure criteria. The results show stress response has a great influence on the strength and bearing of the joint. The Balsawood-steel interface is proved to be critical to the mechanical behavior of the joint. Good agreement between experimental results and numerical predictions is observed.

Research and development of a digital design system for hull structures

Methods used for digital ship design were studied and formed the basis of a proposed frame model suitable for ship construction modeling. Based on 3-D modeling software, a digital design system for hull structures was developed. Basic software systems for modeling, modifying, and assembly simulation were developed. The system has good compatibility, and models created by it can be saved in different 3-D file formats, and 2D engineering drawings can be output directly. The model can be modified dynamically, overcoming the necessity of repeated modifications during hull structural design. Through operations such as model construction, intervention inspection, and collision detection, problems can be identified and modified during the hull structural design stage. Technologies for centralized control of the system, database management, and 3-D digital design are integrated into this digital model in the preliminary design stage of shipbuilding.

Analysis of Ship Evacuation during Tsunami Using AIS （Automatic Identification System） Data

External forces of marine weather, such as waves, currents and wind flows, affect the course and speed of a ship under way. As a result, marine accidents, such as collisions or grounding, may occur, particularly in inshore areas. On coasts where earthquakes and tsunamis occur frequently, such as the Japanese coast, a tsunami that advances into a bay from the open sea is influenced by the submarine topography. It grows into a huge wave that could cause tremendous damage to ships under way and at anchorage. A massive earthquake occurred in the Tohoku and Kanto regions of Japan on March 11,2011. In response, a tsunami alert, a tsunami warning and an advisory were issued for the entire Pacific coast region. This research investigates the evacuation behaviour of ships by AIS （automatic identification system） data in Tokyo Bay after the tsunami warning was issued. The unusual behaviour observed was attributed to the emergency evacuation of ships.

Numerical Research on Wave-making Resistance of Trimaran

A 3D rankine panel method was developed for calculating the linear wave-making resistance of a tri-maran with Wigley hulls. In order to calculate the normal vector and derivative of the body surface accurately, non-uniform rational B-spline (NURBS) was adopted to represent body surface and rankine source density. The radiation condition is satisfied using the numerical technology of staggered grids. Numerical results show that the linear wave-making resistance of the trimaran can be calculated effectively using this method.

Hydrodynamic characteristics of the double-winged otter board in the deep waters of the Mauritanian Sea

In this paper, we tested the hydrodynamic characteristics of a new, double-winged otter board that consists of a forewing, a leading edge slat and a trailing edge flap. Flume experiments were conducted in a circulating flume tank by using a model with an aspect ratio(AR) of 0.85 and a horizontal planform area( S) of 0.09 m^2. The results indicated that the critical angle( α_(cr)) of the model was 44°, whereas the maximum lift coefficient( C_(Lmax)) was up to 1.715, and the door efficiency( K) was 1.122. The attack angle( α) ranged from 30° to 48° and from 10° to 46° when the lift coefficient( C_L) and door efficiency( K) were greater than 1.2 and 1.0, respectively. To compare the difference between double-winged otter board and traditional Morgere Polyvalent Ovale, same model of Morgere Polyvalent Ovale was also tested under the same experimental conditions. The critical angle( α_(cr)) and maximum of lift coefficient( C_(Lmax)) of the doublewinged otter board were 37.5% and 14.6% larger than those of the Morgere Polyvalent Ovale. Therefore, we concluded that the novel, double-winged otter board was more suitable for bottom trawling fisheries in the deep water of the Mauretania Sea due to its better hydrodynamic characteristics and stability.