Construction of GM(2,1)Model for Oscillating Pitch Angle Series

GM(1, 1) is generally used in Grey System Theory which constructs an Ordinary Differential Equation for given se-ries. It is effective for monotone series, and its simulating effect is good and error is small. However, If the series dosen' t havea property of monotone, the simulating effect of GM(1,1) is not fine, and its error gets bigger. In this paper, we use GM(2,1) to handle the oxcillation series, which uses the Method of Minimum Squares in determining the uncertain parameters.The     

Application of the Grey topological method to predict the effects of ship pitching

Ship motion, with six degrees of freedom, is a complex stochastic process. Sea wind and waves are the primary influencing factors. Prediction of ship motion is significant for ship navigation. To eliminate errors, a path prediction model incorporating ship pitching was developed using the Gray topological method, after analyzing ship pitching motions. With the help of simple introduction to Gray system theory, we selected a group of threshold values. Based on an analysis of ship pitch angle sequences over 40 second intervals, a Grey metabolism GM（1,1） model was established according to the time-series which every threshold corresponded to. Forecasting future ship motion with the GM （1,1） model allowed drawing of the forecast curve with effective forecasting points. The precision of the test results show that the model is accurate, and the forecast results are reliable.     

五自由度船舶靠泊装置机构设计及运动分析

为提高船舶靠泊安全系数，减少大型船舶靠泊事故的发生，设计一种以两转动一平移3-RPU并联机构为主体结构的5自由度船舶靠泊装置。基于螺旋理论和修正G-K公式，计算出并联机构的自由度；利用齐次位姿变换建立各连杆矢量方程，推导出并联机构位置正反解数学表达式，基于位置反解表达式求出并联机构的雅克比矩阵，根据雅克比矩阵对3-RPU机构的三类运动学奇异性进行分析；建立机构驱动关节速度与动平台速度之间的关系，对正反解的研究结果进行数值验证，并运用MATLAB对位置和速度反解进行仿真；采用蒙特卡洛法求解并联机构的可达工作空间，并运用MATLAB编程绘制出工作空间三维图和截面图，验证了3-RPU并联机构的可行性，为3-RPU并联机构的应用提供理论依据。     

利用改进的GM（1,1,λ）模型预测舰艇批量生产成本

在分析GM（1,1,λ）模型的建模机理的基础上,指出传统建模方法存在的不足,基于GM（1,1,λ）模型的还原数据模型与原始序列的第一点无关,提出一种可以完全利用全部已知信息的建模方法。同时给出基于遗传算法的GM（1,1,λ）优化模型,优化模型提高了灰色预测的精度。探讨了应用灰色理论建立舰艇批量生产成本预测模型的可行性,并给出了应用实例。     

Full six degrees of freedom coupled dynamic simulation of ship collision and grounding accidents

By taking advantage of the user-defined load subroutine (loadud) and the user common subroutine (usercomm) in LS-DYNA, the authors proposed a new coupled approach for simultaneously calculating structural damage and the planar 3DOF ship motions in ship collisions. The coupled procedure aimed at predicting the detailed structural damage together with reasonable global ship motions. This paper extends the method to consider the full 6DOF ship motions; thus, ship collision as well as grounding accidents can be properly handled. This method is particularly useful for design purposes because the detailed ship hull profile is not needed.A traditional ship maneuvering model is used for the in-plane surge, sway and yaw degrees of freedom with a series of nondimensional coefficients determined from experiments. It is assumed that the out-of-plane degrees of freedom are not coupled with the in-plane ship motions, and there is no coupling among roll, pitch and heave motions. The implementation is verified through free decay tests, and the obtained natural periods show good agreement with theoretical results.Several collision and grounding cases are simulated in which a supply vessel crashes into rigid plates with different orientations. The effects of the roll motion, the heave and pitch motions and the full 6DOF motions are studied. The results are compared with those from a 6DOF decoupled method. Ship motions through the proposed method compare reasonably well with SIMO results. It is found that several consecutive impacts may occur in the simulation of one collision case due to the periodic motions. This is not taken into account in the decoupled method, which makes this method unconservative.     

舰船方位变化规律的灰预测方法研究

对方位序列进行预测对于潜艇作战具有重要的实际意义。应用灰色系统理论，以GM（1，1）模型，残差修正的GM（1，1），等维灰数递补残差修正GM（1，1）模型对目标序列进行预测，可有效克服目标方位序列的非线性和非稳定性，在信息较少的情况下达到精度较高的回归和预测效果。通过实例计算表明，上述计算可快速提供精度较高的较长时间间隔的目标方位，为潜艇作战提供有利信息。     

国外核动力潜艇耐波性理论预报

采用STF理论和Frank源分布-紧密拟合法对国外核潜艇潜望状态进行了纵荡、垂荡、纵摇、横荡、横摇、艏摇和垂向加速度等波频运动耐波性理论预报.给出了不同航速、航向时的规则波运动响应和不同航速、航向、波高、波浪平均周期时的不规则波运动统计值.对典型艇型进行变化稳心高、纵向和横向惯性系数计算.最后对各艇进行了耐波性能比较.     

Control system design and performance evaluation of anti-pitching fins

We have investigated the usefulness of active stabilizing fins to reduce ship pitching under varying forward speeds, and in varying wave lengths. A 4-m self-propelled model ship and an electrohydraulically driven stabilizing fin system were used in our experiment. Pitch angles, pitch rates, and ship forward speeds were measured and fed back to a controller to calculate the deflection angle of the stabilizing fin. The effects of fin nonlinearity on achievable pitch reduction performance are discussed. It is shown that the desired pitch response can only be achieved when the fin is operated in the linear region. The overall dynamic response of the ship approaches open-loop behavior when the degree of nonlinearity is high. This simple analysis of the pitch stablizing system provides basic information to ship designers. Experimental results validate these design guidelines. Received for publication on Feb. 12, 1998; accepted on Dec. 8, 1999     

应用二轴流速仪定向原理估计船舶遭遇的浪向

浪向信息对船舶安全航行至关重要.然而实际海浪是复杂的三维不规则波,目前尚无简易的浪向预报装置,驾驶者只能靠目测初步判断浪向,同时根据船舶在波浪中的运动状态逐步调整航向.本文基于"二轴流速仪定向原理",将航行中的船舶纵摇、横摇运动信息转换为二轴流速仪的输出,实现了以最少的信息采集和数据处理方法以获得基本的浪向信息,为航行中的船舶提供了一较简易、可靠的浪向估计方法.     

基于灰色系统理论的单桩极限承载力预测

根据灰色系统理论的预测模型,建立了预测单桩极限承载力的非等步长GM(1,1)模型。根据工程实例的单桩静载试验结果,预测出其极限承载力,并与相关规范计算值加以比较。分析表明,预测结果的精度能够满足工程需要。     

Prediction analysis on propulsion shafting load based on grey system theory北大核心CSCD

[Objective]The propulsion shafting system is an important part of a ship, and the bearing load directly affects its operating state and service life. In this paper, bearing load under hull deformation is studied using grey system theory. [Method] First, according to the empirical formula of the relative displacement of each bearing caused by the deformation of the hull of a 57 000 DWT oil tanker, the relative displacement of each bearing is calculated and input into a finite element model, and the load value of each bearing is output. On this basis, grey relationship analysis of grey system theory is introduced to study the influence degree of stern bearing displacement on the load of each bearing, and the relative change of the load of each bearing caused by the displacement of the stern bearings is analyzed. A GM (1,1) prediction model is then established for the bearing load considering the bearing displacement conditions, and the hull deformation-fitting and prediction of each bearing load are made. [Results]The results show that grey relationship analysis can effectively reflect the influence of hull deformation on bearing load. The GM (1,1) prediction model has high accuracy and prediction errors less than 6.0%, and the model test indexes can represent the accuracy of the prediction. [Conclusion]Grey system theory is effective and practical in research on propulsion shaft load. It can accurately predict bearing load under bearing displacement, giving it certain reference value for research on bearing load under actual sailing conditions. © The Author(s) 2022.     

一种具有负荷限制功能的调距桨最佳启动算法

本文对调距桨系统的快速启动过程建模分析,研究出一种具有负荷限制功能的调距桨最佳启动算法。通过计算机编程仿真,结果表明在一定的条件下,该算法可以得到较优的启动路径。采用该启动路径,主机能合理控制转速与螺距,在不超负荷状态下快速平稳地提高输出功率,很好地增强船舶启动过程中的机动性与灵活性。该算法对实际的船舶航行控制启动过程有重要的参考价值。     

基于双GPS接收机的船舶定向系统实现

构建了基于双GPS接收机的船舶定向系统软件和硬件系统.在讨论接收机间单差相位观测方程以及接收机和卫星间双差相位观测方程的基础上,提出了一种快速整周模糊度求解方法,来解算双GPS天线形成的基线矢量,从而得到船舶的航向角和俯仰角.通过静态实验和动态实验结果验证了该系统的可行性.     

船舶CPP推进系统的网络控制

可调螺距螺旋桨(Controllable Pitch Propeller,简称调距桨CPP)是船舶推进系统的主要设备。随着船舶装备的不断改进,控制系统已发展到以计算机为核心的网络控制系统。针对船舶智能推进系统优化设计的应用背景,引入网络控制技术构成分布式CPP控制系统,并采用自适应模糊逻辑调节法构成网络PI控制器,以补偿网络时延对控制系统稳定性的影响。     

优化的新陈代谢GM(1,1)模型在港口吞吐量预测中的应用

针对常规GM(1,1)模型存在的不足,尝试用优化的新陈代谢GM(1,1)模型来进行预测,并加以比较。结论表明:优化的新陈代谢GM(1,1)模型能够明显地提高预测精度,增加预测的可靠程度,从而为港口的发展战略研究提供一定的技术支持。     

纵摇容器中液体晃荡的非线性数值模拟

在海洋工程领域,液体晃荡是一种普遍存在的物理现象。对于船舶而言,转动比平动有着更重要的影响。该文针对纵摇容器中的液体晃荡问题,采用高阶边界元方法建立自由水面满足完全非线性边界条件的时域数学模型。通过大地坐标系和随体坐标系之间的坐标变换,使得计算域仅控制在随体坐标系内。求解中采用半混合欧拉—拉格朗日方法追踪流体瞬时水面,运用四阶龙格库塔方法更新下一时间步的波面和速度势。通过与已发表试验和数值结果的对比,验证了建立模型的准确性。进而开展大量数值试验研究容器纵摇运动频率、纵摇转动中心和容器中布置一竖直隔板对晃动波面与荷载的影响。     

船舶气囊下水过程中船体倾角变化的测试与研究

为研究船舶气囊下水过程船体横向和纵向倾角的变化过程,采用基于工控机的倾角测试系统。该系统由倾角传感器、RS-232串行总线及工控机等元件组成。通过对测试结果的分析计算,结论表明：该船舶在气囊下水过程中,最大纵向倾角发生在船舶艉落阶段,最大值为1．8。左右,下水过程平稳,没有明显的艏落现象发生,同时船舶下水过程横向摇摆幅度很小。     

基于N-S方程的航行船舶辐射问题数值模拟

基于N-S(Navier-Stokes)方程,进行了航行船舶辐射问题的数值模拟,包括强制垂荡和强制纵摇的模拟.计算了船舶垂荡和纵摇的附加质量和阻尼.数值模拟中,控制方程--BANS(Reynolds Averaged Navier-Stokes)方程和连续性方程使用有限体积法离散,非线性自由面采用VOF方法处理.文中给出了以不同航速前进的船舶强制垂荡和纵摇的力与力矩,以及船舶垂荡和纵摇的附加质量系数和阻尼系数,并与DUT(Delft University of Technology)的试验数据进行了比较,二者吻合良好.     

基于回声状态网络的船舶摇荡连续预报方法研究

回声状态网络（ ESNS）是一种新型递归神经网络,可通过对有限的已知样本进行训练,建立非线性模型来预报未知样本。该算法在解决非线性问题时具有一定优势。无需知道海浪的先验信息和船舶航行姿态的状态方程,仅利用实测的船舶横摇、纵摇历史数据,寻求规律即可进行实测摇荡数据的极短期预报。仿真结果表明,该算法在预报15 s以内可达到较高的预报精度,通过预报窗口的平移,可以进行连续在线预报。     

Work simplificafion through the tansformation of work on board

Through a series of research on 10 Japanese ships since 1961, it was found that the relationship between number of crew and the resulting structural change of work on board ship can be formulated by a linear regression. Some of the major findings that are obtained from this new method are summarized as follows. As the number of crew decreases, the proportion of work for operating the ship (manoeuving and controlling work) increases, while the proportion of work which is not directly related to the operation decreases. This structural change can be attributed to work simplification resulting from four types of the transformation of work:

(a) The replacement of man'al work by putting machines on board.

(b) The transformation of work on board into work done by machines on shore.

(c) The transfer of work previously done on board to the shore.

(d) The transformation of work within a ship.