基于MATLAB的矩阵变换器空间矢量调制策略仿真

首先简述了交一交矩阵变换器的工作原理及调制策略,然后分析了空间矢量调制策略的算法实现,着重讨论了矩阵变换器的建模与仿真．在此基础上建立了基于MATLAB的矩阵变换器仿真模型,并给出了仿真波形．仿真结果验证了模型及控制策略的正确性．     

实时水中目标辐射噪声仿真技术研究

水中目标辐射噪声主要包括平滑连续谱和线谱2部分,对平滑连续谱建立的功率谱数学模型,可以按照需求确定模型参数,通过Levinson算法递推出AR模型参数.对线谱的主要来源进行了分析,推导了线谱的简要模型,并考虑了多普勒效应.给出了水中目标噪声的简要仿真模型,并提出一种在微机平台上利用DirectSound接口,使用普通声卡对辐射噪声进行播放的方法,利用信号量方法解决了实时无间断播放的问题,可用于声呐员训练和航行模拟系统的听觉仿真.     

AN EFFECTIVE HUMAN LEG MODELING METHOD

IntroductionFFD is a widely used technique in the field ofsolid modeling and computer animation.Seder-berg and Parry introduced the conceptof FFD[1] ,and Barr provided the basic deformation methodfor FFD[2 ] .Although there are several versionsof FFD in the related literature[3～ 6 ] ,they havethe same basic idea:1 Constructa lattice space.The space can be of any shape,not restricted toparallel- piped cube[5 ] .2 Embed the object intothe lattice space.In other words,impose a localcoordi…     

非参数估计中核估计的构造及相合性

讨论了非参数估计中的核估计方法,对于相互独立同分布的随机变量的密度函数引进了新的估计量方法,并且讨论了此估计的量的逐点相合性,求出了未知密度函数的区间估计,最优窗宽。     

Parametric vibration and vibration reduction of cables in cable-stayed space latticed structure

Mechanical model and vibration equation of a cable in cable-stayed sparse latticed structure (CSLS) under external axial excitation were founded. Determination of the mass lumps and natural frequencies supplied by the space latticed structure (SLS) was analyzed. Multiple scales method (MSM) was introduced to analyze the characteristics of cable's parametric vibration, and the precise time-integration method (PTIM) was used to solve vibration equation. The vibration behavior of a cable is closely relative to the frequency ratio of the cable and SLS. The cable's parametric vibration caused by the external axial excitation easily occurs if the frequency ratio of the cable and SLS is in a certain range, and the cable's vibration amplitude varies greatly even if the initial disturbance supplied by SLS changes a little. Furthermore, the mechanical model and vibration equation of the composite cable system consisting of main cables and assistant cables were studied. The parametric analysis such as the pre-tension level and arrangement of the assistant cables was carried out. Due to the assistant cables, the single-cable vibration mode can be transferred to the global vibration mode, and the stiffness and damping of the cable system are enhanced. The natural frequencies of the composite cable system with the curve line arrangement of assistant cables are higher than those with the straight-line arrangement and the former is more effective than the latter on the cable's vibration suppression.     

基于APDL高速铝合金车体参数化建模

基于ANSYS的参数化编程语言APDL,以车体主要板厚度、车体高度、长度、窗体参数等主要结构尺寸为参数,采用模块化设计理念,建立了高速铝合金车底架、侧墙、顶板、端墙等参数化几何模型和有限元模型,并组合成整体模型.本研究可通过简单的改变参数产生不同的车体几何模型和不同网格密度的有限元模型,以适应不同问题数值仿真的要求,并为对车体的优化设计打下基础.研究表明,铝合金车体的参数化建模极大的提高了建模的效率和精度,可简单改变参数得到不同模型以适应不同问题的要求.     

基于BIM的中低速磁浮土建构件管理平台开发

通过对当前中低速磁悬浮线路BIM技术应用的分析调研发现,国内外轨道交通BIM应用领域存在建模工作量巨大、各分项工程之间关联性差等问题.为加速推进工程建设信息化在中低速磁悬浮建设中的应用,提出一种结合正向设计理念的中低速磁浮土建构件库信息管理平台架构方法,着重从BIM技术的角度来研究构件拆分、构件模型建立及构件库管理平台...     

岸边集装箱起重机的数字化样机设计系统研究

基于知识工程理论和专家系统,综合运用多领域仿真、交互式用户界面、虚拟现实和数据库等技术,构建岸边集装箱起重机的数字化设计研发系统。该系统主要包括参数化驱动的三维设计模型、有限元分析模型、动力学分析模型和吊装分析模型等,通过运行结构的分析与优化、动力学分析、现场安装仿真等模块,可以实现虚拟样机的参数化驱动设计,大大减少了重复建模的工作量,该系统还可用于岸边集装箱起重机的创新设计、测试和评估。