海面多源噪声的高阶循环频谱分析研究

海面噪声对于船舶探测、水声系统以及水下装置都具有非常重要的应用价值。本文主要对多源噪声的特征进行分析,并给出一种基于高阶循环谱的海面多源噪声特征分析方法。利用循环平稳信号模拟海面噪声,能够有效记录噪声周期中各状态的经历,使其更加逼近真实情况。     

基于幅值域参数的船舶液压系统故障诊断研究

针对振动频谱时频域特征信号在船舶液压系统故障诊断领域存在的不足,分析了不同幅值域参数对不同故障存在的敏感度差异,提出了基于幅值域特征分析的多信号、多参数的故障诊断方法,通过5类幅值域无量纲参数和某型船艇装备液压缸4例典型故障对这一方法进行了验证。     

基于AutoMod的补给保障船物资转运流程仿真分析

结合补给保障船船内空间有限的特征,提出船内物资转运的规划和设计方法,并开展船内干货物资特征分析、转运流程规划、实物模拟试验。基于AutoMod仿真分析相关参数对转运流程的影响,确定船内物资转运流程的瓶颈点,形成船内物资转运流程中相关参数的优化配置。     

现代统计学理论的舰船交通数据特征分析

舰船交通数据特征具有非平稳随机性,通过提取舰船交通数据特征信息,实现船舶优化调度,缓解船舶出海拥堵,提出一种基于现代统计学理论的舰船交通数据特征分析方法,根据出海交叉口构造船舶交通网络体系结构,采用统计采样方法进行舰船交通数据的原始信息采集,采集的交通数据有交通流量数据、船舶行程时间、行驶频次,构造水网分布式可靠度的连接函数,以行程时间可靠性为约束指标参量进行舰船交通数据的统计自回归分析,实现舰船交通数据的统计特征提取,从而分析船舶交通的关联规则性信息,实现舰船优化调度。试验结果表明,采用该方法进行舰船交通数据特征分析,能实现对舰船出海流量和拥堵的准确预测评估,数据分析的统计性能较好,准确可靠。     

舰船尾迹SAR图像特征的谱分析研究

图像纹理在频率空间的分布具有规律性,可以通过对图像进行频谱分析来提取纹理特征。根据SAR成像机理对舰船尾迹SAR图像进行了仿真研究,采用周相谱法对图像的二维功率谱作一维变换处理,提出基于归一化能量谱的图像谱特征分析方法,并给出了不同探测参数下尾迹SAR图像谱特征的仿真图。结果表明,该方法可有效地消除海面背景的影响,实现舰船尾迹特征检测的定量分析。     

内弹道两相流方程的初边值条件个数的研究

对一维内弹道两相流方程进行特征分析，用特征理论和量级分析的方法，对一维内弹道两相流方程的初边值条件个数进行研究，本文所得结论与内弹道两相流数值模拟实践相一致。     

船舶柴油机润滑油水污染类型鉴别研究

文章针对船舶柴油机润滑油水污染类型鉴别需要,确立了污染类型鉴别主要区分特征,分析了传统水污染类型鉴别程序存在的问题,并对程序相应进行了改进。基于实测数据和理论推算,讨论了不同情况下的水污染类型鉴别数值。最后,在实际案例中应用上述程序方法对水污染类型进行了鉴别,从而说明程序方法的合理性。     

基于最大熵谱估计的舰船静电场实时检测方法

舰船静电场是海水中舰船产生的物理场之一,是很难被隐身的目标特征信号.以往对静电场的检测方法都是基于信号的时域特征,低信噪比情况下,检测效果差.通过对舰船静电场的频域特征分析发现,其能量主要集中在低频段,利用这个特点,提出了一种基于最大熵谱估计(MESE)的舰船静电场实时检测的方法.首先对舰船静电场信号进行最大熵谱估计,然后提取低频段功率谱值作为特征量,通过设定的浮动阈值进行分段功率谱滑动检测,用实船数据对该方法进行了验证,取得了较好的效果.     

基于特征造型的成组夹具CAD／CAPP／CAM集成系统

本文介绍了一个基于特征造型的成组夹具ＣＡＤ／ＣＡＰＰ／ＣＡＭ集成的系统，该系统由夹具ＣＡＤ、ＣＡＰＰ和ＮＣ程序自动生成三个分系统组成。按形状和功能进行特征分类，自动生成特征型数据文件；利用一个专门研制的程序从特征造型数据中提取ＣＡＰＰ输入数据和待加工表面的几何数据，生成零件加工的ＮＣ刀轨是依据来自ＣＡＰＰ模块的零件代码化的加工过程数据和由特征造型数据中提取的零件几何数据。     

基于源代码插桩的C程序内存使用错误动态检测

针对C程序内存使用错误的预防和处理方法分基于静态分析和动态分析两类。静态分析工具研制复杂，目前还没有得到广泛使用的高效工具。动态分析又分为基于目标代码和源代码插桩分析两类。由于缺少完整的语法、语义信息，基于目标代码的分析有时对错误的捕捉、定性不够精确。基于源代码的分析由于其信息的完整可以达到对错误的最精确报告。本文对C程序中的内存使用错误进行了分析，并讨论了一个C程序内存错误动态检测工具的设计思想，给出了系统流程、关键数据结构、错误捕捉方法的设计。     

同心球壳-球体系感应磁场的解析解

考虑薄壳体和非薄壳体结构的感应磁场可提高舰艇感应磁场数值建模精度,开发相应的磁场数值程序包时,磁场解析解模型是验证程序包数值准确性的有效手段。同心球壳-球体系模型是验证同时考虑薄壳体和非薄壳体感应磁场数值准确性的理想模型。基于分离变量法推导了该模型感应磁场的解析解,以积分方程法和有限元法为参照,解析解误差均在5%以内,表明了导出解析解表达式的准确性。     

基于ANSYS的船舶槽形舱壁有限元建模方法及其程序实现

有限元法已经广泛应用于船舶与海洋工程结构设计和分析计算过程中.基于ANSYS有限元工程分析软件,提出一种建立比较复杂的槽形舱壁结构模型的方法.通过对20,000DWT化学品/成品油船的结构设计,证明该方法的可行性和可靠性.应用Visual Basic6.0程序设计软件编制了相应的计算机程序,实现了ANSYS命令流文件的自动生成,提高了模型建立的自动化.     

DirectSound技术在模拟器中的应用

设备工作声音的控制是模拟器开发的重要组成部分。本文在分析真实设备工作声音特点的基础上介绍了利用DireccSound技术控制模拟设备工作声音的方法,其中重点讨论了专用声音播放类和声音控制的VC 程序代码。用该方法控制设备工作声音,达到了模拟的目的。     

湍流激励下简支平板振动特性的解析法研究

解析法基于随机激励理论,采用湍流脉动压力的Corcos模型作为输入,结合考虑流固耦合时平板的频响函数,求解得到平板振动速度的自功率谱密度。计算结果同已有文献吻合较好,证明了解析法的正确性。同时研究结果表明：湍流激励下平板的振动特性体现了平板本身的固有特性;随着来流速度的增大,平板振速的均方谱密度幅值按一定的数值关系增大。     

Application of analytical model in the prediction of dynamic responses and fatigue damage of flexible risers: Part II – Dynamic analysis of flexible risers in large-scale domain using a direct moment correction method

In recent years, the dynamic responses of flexible risers have been the focus of many researchers. Most flexible risers undergo a substantial level of irregular motion from environmental loadings, which involves a continuous slip of helical wires. The slip of helical wires especially leads to a hysteretic effect by reducing the bending stiffness, making it hard to predict the dynamic responses of flexible risers. The current study, as an extension to Part I, presents a new large-scale dynamic analysis method for flexible risers. The suggested method creates a large-scale model for the dynamic analysis that considers a geometric and bending nonlinearity of flexible risers. The kinematics of each beam element is formulated based on a Green-Lagrangian strain and the interaction with the seabed, providing a realistic analysis of flexible risers. In particular, the current study introduces a direct moment correction method that modifies the internal force vector using an improved analytical model. The improved analytical model is assigned at each node of the large-scale model and estimates an accurate bending hysteresis curve considering the effect of shear deformation and varying tension. The suggested method corrects the bending moment and shear force of all beam elements based on the bending hysteresis curves obtained from the improved analytical model, by which a complex bending behavior of flexible risers is reflected in a large-scale domain. As a result, this study achieves a more accurate prediction of the dynamic responses and fatigue damage of flexible risers. A new dynamic analysis program, called OPFLEX, is developed herein based on the suggested analysis method. Using the developed program, the current study conducts several numerical investigations to identify the effect of the shear deformation and varying tension. Consequently, it is confirmed that the shear deformation of internal layers reduces the fatigue damage of helical wires by delaying the increase of internal stress. It is also identified that the effect of varying tension deteriorates the fatigue life of flexible risers through a continuous change of contact pressure during bending.     

船舶冷藏系统热负荷计算研究

分析船舶冷藏系统热负荷的特点，尤其针对大型水面船舶冷藏系统热负荷的复杂性，研究热负荷计算方法，编制船舶冷藏系统热负荷计算程序代替手工计算，大大提高设计效率和质量。     

Influence on the hydrodynamic performance of a variable vector propeller of different rules of pitch angle change

To design a more effective blade pitch adjustment mechanism,research was done on changes to the hydrodynamic characteristics of VVPs(Variable Vector Propeller) caused by different rules for changing pitch angle. A mathematical method for predicting the hydrodynamic characteristics of a VVP under unsteady conditions is presented based on the panel method. Mathematical models for evaluation based on potential flow theory and the Green theorem are also presented. The hydrodynamic characteristics are numerically predicted. To avoid gaps between panels,hyperboloidal quadrilateral panels were used. The pressure Kutta condition on the trailing edge of the VVP blade was satisfied by the Newton-Raphson iterative procedure. The influence coefficients of the panels were calculated by Morino's analytical formulations to improve numerical calculation speed,and the method developed by Yanagizawa was used to eliminate the point singularity on derivation calculus while determining the velocities on propeller surfaces. The calculation results show that it's best for the hydrodynamic characteristics of the VVP that pitch angle changes follow the sine rule.     

New Model and Simulation of Condenser for Ship Nuclear Power Plant

A new reasonably perfect dynamic mathematic model has been established for condenser used in ship nuclear powerplant according to its structural features and Operating principle. The model has been solved by the Runge-Kutta method. Andan analysis program has been developed for dynamic numerical simulation under steady operation condition, disturbance condi-tion, and accident condition. The dynamic characteristics of condenser has been calculated and analyzed under several kinds of     

基于Morabito方法的滑行艇喷雾详细研究的计算机程序开发(英文)

Recently, Morabito(2010) has studied the water spray phenomena in planing hulls and presented new analytical equations. However, these equations have not been used for detailed parametric studies of water spray around planing hulls. In this paper, a straight forward analysis is conducted to apply these analytical equations for finding the spray geometry profile by developing a computer program based on presented computational process. The obtained results of the developed computer program are compared against existing data in the literature and favorable accuracy is achieved. Parametric studies have been conducted for different physical parameters. Positions of spray apex are computed and three dimensional profiles of spray are examined. It is concluded that spray height increases by an increase in the speed coefficient or the deadrise angle. Ultimately, a computational process is added to Savitsky's method and variations of spray apex are computed for different velocities. It is shown that vertical, lateral, and longitudinal positions of spray increase as the craft speed increases. On the other hand, two new angles are defined in top view and it is concluded that they have direct relation with the trim angle. However, they show inverse relation with the deadrise angle.     

欧标任意形状钢筋混凝土断面的正截面极限承载能力计算

为了提高钢筋混凝土双向受弯构件配筋的精细化程度,基于欧洲混凝土标准的设计方法对任意形状钢筋混凝土断面正截面极限承载能力进行分析,针对钢筋混凝土材料应力-应变关系中的分段特性,采用高效的动态网格更新技术和高斯积分方法对钢筋混凝土构件正截面内力进行求解并编写相关程序,该程序能输出构件配筋正截面极限承载能力的三维包络面数据,可结合构件有限元全节点内力结果分析配筋的可行性。结果表明,该方法计算速度快、精度高,同时解决了设计时仅对单一节点、单一工况验算的便利性和完备性问题。