压电材料智能力矩控制器对具有不确定参数升船结构顶部厂房地震反应的鲁棒控制

文中建立了压电材料智能力矩控制器对具有不确定参数升船结构顶部厂房地震反应鲁棒控制的设计计算方法，并对中国某升船结构的等效结构体系进行了仿真分析。计算结果表明，智能力矩控制器能有效地减小顶部厂房的鞭梢效应。在考虑顶部厂房因端部山墙引起的侧移刚度不确定性的条件下，智能力矩鲁棒控制器的控制效果和稳定性要优于常规的主动控制器。     

基于弧段检测的高频地波雷达特定目标航迹跟踪方法研究

本文对现有的高频地波雷达目标跟踪方法进行了概述,提出了一种地波雷达目标长时连续跟踪的方法,基本思想是:充分挖掘航迹弧段特征,基于特征对船只运动建模,并结合杂波背景进行融合决策。进一步,为了达到长时间连续跟踪的需求,借鉴深度学习的思想,利用新获取的弧段数据对算法估计结果不断递归校正,使得随着获取数据的增加跟踪越准确。该方法适用于杂波环境且在航道附近存在众多干扰船只的情况下对机动目标航迹的实时稳定跟踪,为高频地波雷达在复杂干扰环境下特定目标持续跟踪提供理论基础和方法指导,为充分发挥地波雷达在海上监视监测中的作用提供技术支撑。     

Numerical Simulation and Experimental Research on Wake Field of Ships Under off-Design Conditions

Different operating conditions (e.g. design and off-design) may lead to a significant difference in the hydrodynamics performance of a ship, especially in the total resistance and wake field of ships. This work investigated the hydrodynamic performance of the well-known KRISO 3600 TEU Container Ship (KCS) under three different operating conditions by means of Particle Image Velocimetry (PIV) and Computational Fluid Dynamics (CFD). The comparison results show that the use of PIV to measure a ship’s nominal wake field is an important method which has the advantages of being contactless and highly accurate. Acceptable agreements between the results obtained by the two different methods are achieved. Results indicate that the total resistances of the KCS model under two off-design conditions are 23.88% and 13.92% larger than that under the designed condition, respectively.     

初始凸包对改进快速凸包算法效率的影响

针对目前众多采用了改进的快速凸包算法对给定的平面海量离散点集生成凸包的文献中,没有明确指出其初始凸包的形式(四边形或八边形)对算法效率的影响的问题,该文对凸包的生成过程进行了深入分析,并进行了大量的实验。通过比较这些实验的结果,发现以四边形或八边形作为初始凸包均能有效地提高算法效率,但在相同的条件下,以八边形作为初始凸包时,并不能将算法效率进一步提高,与以四边形作为初始凸包相比,其实际的执行效率不升反降。实验结果表明以四边形作为初始凸包时算法效率最佳。     

拖曳线列阵振荡幅值响应特性

通过欧拉角的变换把拖曳线列阵微元段矢量动力平衡方程在局部坐标系下展开，在时间和空间上作中心差分数值离散平衡方程。将尾绳阻力作为线列阵尾端点的张力，改善因尾端张力为零引起的差分方程奇异性。取有关文献资料中的两个拖曳线列阵进行了拖点振荡响应计算，计算结果与相应文献资料中线性理论的计算和试验结果基本吻合。最后由仿真计算讨论了拖曳线列阵参数变化对拖点垂向和横向的谐振稳态响应特性。计算结果表明影响拖曳线列阵振荡响应的主要参数是由拖缆长度、拖点航速和拖点振荡因频率构成的无因次振荡频率。     

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.     

Aerodynamic characteristics of a hybrid trimaran model

Ultra fast marine vehicles can substantially benefit from aerodynamic unloading. The subject of this study is aerodynamics of a hybrid trimaran that comprises three wave-piercing planing hulls and a wing-shaped superstructure. This configuration is characterized by high efficiency and good seaworthiness at speeds about twice those of contemporary fast ferries and combat ships. Aerodynamic coefficients of the above-water structure of the hybrid trimaran were measured in a wind tunnel. A computer code based on the vortex lattice method is applied for modeling steady aerodynamics of this structure in a range of attack angles. The application of an interceptor at the pressure side of the wing is shown to produce significant increase in aerodynamic lift.     

船载式远程高精度水声定位系统

本文比较了各种水声定位跟踪系统的特点，由此可明显看出长基线模式的船载式水声定位跟踪系统将兼有使用方便、适用性强、定位精度高、作用距离远的优点，仔细分析了要实现这类系统的关键技术难题，介绍了我国自行研制的一个船载式远程高精度水声定位系统的组成和工作原理，该系统还率先突破了主动式水声定位系统中非模糊距离Ｒｍａｘ＝ＣＴ的原理性限制，使系统可进行远程，高数据率跟踪定位     

Manoeuvring behaviour of ships in extreme astern seas

In an attempt to contribute to efforts for a robust and effective numerical tool addressing ship motion in astern seas, this paper presents the development of a coupled non-linear 6-DOF model with frequency dependent coefficients, incorporating memory effects and random waves. A new axes system that allows straightforward combination between seakeeping and manoeuvring, whilst accounting for extreme motions, is proposed. Validation of the numerical model with the results of benchmark tests commissioned by ITTC's Specialist Group on Stability demonstrated qualitative, yet not fully satisfactory agreement between numerical and experimental results in line with other predictive tools. The numerical results indicate that the inclusion of frequency coefficients definitely affects the accuracy of the predictions. In order to enhance further the numerical model and obtain useful information on motion coupling, extensive captive and free running model tests were carried out. Good agreement with the experimental results was achieved. These studies provide convincing evidence of the capability of the developed numerical model to predict the dangerous conditions that a ship could encounter in extreme astern seas. As a result, it could offer new insights towards establishing relationships linking ship behaviour to design, environmental and operational parameters.     

坐底式整平船对流场影响的试验研究

通过整平船在长江口南导堤 Se段工程对流场影响的模型试验 ,得出各断面在不同潮位、流速、流向情况下 ,只有导堤和有整平船作业时会对周围流场有影响 ,为施工方案的比选以及施工中应采取的措施提供了可靠的依据。