长江下游感潮河段造床流量计算研究

针对长江下游大通至长江口的感潮河段,借助潮流数学模型,计算造床流量,研究其特点及变化规律。研究表明:计算感潮河段造床流量时,流量输沙率法使用方便,计算结果较为合理;对于天生港以上河段,存在两个造床流量,而对于徐六泾以下河段,则存在一个造床流量群;大通至仪征河段的造床流量沿程变化较少,自仪征开始造床流量沿程逐渐提高,主要应与纳潮量沿程增加有关。     

光电跟踪系统伺服控制算法研究

伺服控制直接决定了光电跟踪系统的性能,文章采用模糊神经网络控制算法,具有参数学习和结构学习功能,通过Matlab仿真对比发现无论是动态、静态性能还是鲁棒性方面都要优于传统的PID控制以及模糊控制,表现出很好的准确性和快速性,为光电跟踪系统伺服控制设计提供了一种可行的技术方案.     

基于声辐射特性分析的舱壁边缘开孔参数优化设计研究

为满足潜艇设计整体性、实用性和技术性要求,结构组、管路组及机电组等需对特殊舱壁边缘进行开孔处理.为研究舱壁边缘开孔对潜艇水下振动和声辐射特性的影响,以两舱段环肋圆柱壳为研究对象,采用结构有限元耦合流体边界元方法,通过FORTRAN和DAMP混合编程,计算了在不考虑开孔加强结构条件下不同开孔位置、开孔数目及开孔大小的圆柱壳水下辐射声功率曲线,得到基于声辐射特性的开孔参数优化方案,为潜艇舱壁结构设计提供合理依据.     

基于改进FBS理论的浮筏隔振系统计算方法

  目的  为了研究几何参数对浮筏隔振系统性能的影响,  方法  运用参数化建模技术建立筏架的参数化有限元模型,以振级落差作为隔振效果的评价参数。在弹性筏架总质量不变的前提下,分析筏架几何参数对系统隔振性能和筏架固有频率分布的影响。  结果  结果表明：筏架的几何参数对浮筏隔振系统隔振效果的影响主要体现在中、高频段;筏架高度、长宽比、肋板数目是影响浮筏隔振系统隔振性能和筏架固有频率分布最重要的几何参数;调整筏架几何参数是避开机械设备激振频率的有效途径之一。  结论  所得结论对浮筏隔振系统设计具有一定的工程实用价值。     

Influence of pre-injection control parameters on main-injection fuel quantity for an electronically controlled double-valve fuel injection system of diesel engine

A simulation model of an electronically controlled two solenoid valve fuel injection system for a diesel engine is established in the AMESim environment.The accuracy of the model is validated through comparison with experimental data.The influence of pre-injection control parameters on main-injection quantity under different control modes is analyzed.In the spill control valve mode,main-injection fuel quantity decreases gradually and then reaches a stable level because of the increase in multi-injection dwell time.In the needle control valve mode,main-injection fuel quantity increases with rising multi-injection dwell time;this effect becomes more obvious at high-speed revolutions and large main-injection pulse widths.Pre-injection pulse width has no obvious influence on main-injection quantity under the two control modes;the variation in main-injection quantity is in the range of 1 mm3.     

长江中游典型河段整治关键参数的应用研究*

利用数值模拟手段,针对长江中游藕池口河段、牯牛沙河段典型碍航浅滩,将三峡水利枢纽运用后新的航道整 治参数确定方法应用到具体河段航道整治工程中,对航道整治关键参数进行实践检验,为相关研究提供应用基础。数学模 型计算结果表明：在此种整治参数下,经过典型水文过程后可达到规划的航道尺度,整治工程达到了预期的整治效果,新 的航道整治参数理论成果适用于目前三峡水利枢纽运用后长江中游浅滩的航道整治。     

水下运动体横-滚控制弹道稳定性探讨

本文根据水下运动体空间运动方程与横-滚控制方程,探讨了控制参数与舵机特性对控制弹道稳定性的影响.     

强夯数值模拟及设计参数研究

根据强夯处理高填方时土体存在局部大变形的特点,采用非线性有限元理论,导出弹塑性大变形有限元动力平衡方程,对高填方强夯处理进行数值模拟,得到夯坑形状、土体应力变化及塑性区开展等结果,并依据数值模拟结果对强夯加固的主要设计参数进行初步探讨。     

Onboard tuning of vessel seakeeping model parameters and sea state characteristics

It is essential for a safe and cost-efficient marine operation to improve the knowledge about the real-time onboard vessel conditions. This paper proposes a novel algorithm for simultaneous tuning of important vessel seakeeping model parameters and sea state characteristics based on onboard vessel motion measurements and available wave data. The proposed algorithm is fundamentally based on the unscented transformation and inspired by the scaled unscented Kalman filter, which is very computationally efficient for large dimensional and nonlinear problems. The algorithm is demonstrated by case studies based on numerical simulations, considering realistic sensor noises and wave data uncertainties. Both long-crested and short-crested wave conditions are considered in the case studies. The system state of the proposed tuning framework consists of a vessel state vector and a sea state vector. The tuning results reasonably approach the true values of the considered uncertain vessel parameters and sea state characteristics, with reduced uncertainties. The quantification of the system state uncertainties helps to close a critical gap towards achieving reliability-based marine operations.     

计算机辅助船体分段吊装强度计算方法及系统开发

分段吊装方案的结构补强设计主要依据设计人员的现有经验进行,存在理论不足、材料浪费、优化性差等诸多问题。为了改善分段吊装方案的结构补强设计状况,开发了专门针对VLCC船体分段吊装强度计算系统。论文在研究Tribon系统内分段结构及数据抽取方法的基础上确定了分段重构所需的基本参数,并在ANSYS系统内实现了分段有限元模型的重构,该过程完全由外部程序调用相应的工程软件完成,最终通过输出有限元分析结果来确定结构是否需要补强及补强形式,从而使得分段吊装方案的结构补强设计更加合理、规范。