窄带滤光片光学极值法直接监控的光学设计

窄带滤光片是应用于光谱学、激光、天文物理学、通信等各个领域的光学组件,精确控制每一层膜厚是制备滤光片的困难所在.采用光学极值法直接监控工件,可以同时制备多件滤光片.设计了监控光路和信号获得电路,通过探测到的测试信号,监控薄膜膜厚,实现了直接监控.     

Specific energy optimization in sawing of rocks using Taguchi approah简

This work aims at selecting optimal operating variables to obtain the minimum specific energy （SE） in sawing of rocks. A particular granite was sampled and sawn by a fully automated circular diamond sawblades. The peripheral speed, the traverse speed, the cut depth and the flow rate of cooling fluid were selected as the operating variables. Taguchi approach was adopted as a statistical design of experimental technique for optimization studies. The results were evaluated based on the analysis of variance and signal-to-noise ratio （S/N ratio）. Statistically significant operating variables and their percentage contribution to the process were also determined. Additionally, a statistical model was developed to demonstrate the relationship between SE and operating variables using regression analysis and the model was then verified. It was found that the optimal combination of operating variables for minimum SE is the peripheral speed of 25 m/s, the traverse speed of 70 cm/min, the cut depth of 2 cm and the flow rate of cooling fluid of 100 mL/s. The cut depth and traverse speed were statistically determined as the significant operating variables affecting the SE, respectively. Furthermore, the regression model results reveal that the predictive model has a high applicability for practical applications.     

Optimal blank design based on finite element method for blades of large Francis turbines

Metal pressing process that is widely used in industries has advantages over casting process for producing large Francis turbine blades from thick plates. Prior to the pressing process, blank design is firstly performed to determine flat blanks. The traditional trial and error approach is not applicable to blade design for Francis turbines that are not standard due to hydraulic characteristics of power plant sites. The rapid development of computing technology makes it possible to obtain optimal flat blanks by numerical modelling and simulation. In this paper, inverse finite element approach is investigated for blank design and an elasto-plastic model has been built using the well-known commercial software ANSYS. Numerical simulations for blade unfolding models with thick shell elements, solid elements and shell elements have given results with negligible differences. Unfolding tests with simple geometries have been carried out and the numerical results agree well with the analytical solutions. A large and thick shape of a Francis turbine blade for a hydropower plant has been successfully unfolded by inverse FE model. Sensibility analysis shows that the middle surface of the flat blank is independent of blade thickness. For ensuring the machining of the blade after the pressing process, a new contour is obtained by extending the boundary of the flat blank provided by the numerical model. This research may provide a useful tool for optimal blank design of Francis turbine blades.     

具有区间峰值的曲面伸缩因子及其实验

为了改进参数曲面自由变形方法,构造了一种新的伸缩因子函数,它不仅具有以往文献所引入的伸缩因子的特性,还可以在区域上达到峰值,从而克服现有的伸缩因子仅在一点达到峰值的不足。使用新的伸缩因子去作用待变形的曲面方程,从而使曲面发生形变,通过交互改变控制参数来控制曲面的形状,使其能够更好地表示一些实体的外型。实验表明,该方法数学背景简单,易于控制,重复使用可获得丰富的变形效果。适用于几何造型、计算机动画、CAD/CAM等领域。     

基于积分二次约束时滞不确定系统的H∞可靠性控制

把基于积分二次约束H∞可靠性控制方法引入状态与时滞不确定系统。通过LMI方法导出无扰动时滞系统具有二次约束H∞可靠性控制的时滞依赖标准,降低有关判定系统鲁棒稳定性条件的保守性。通过推导获得参数与时滞不确定系统的时滞依赖标准。通过数例说明所得结论。     

不规则网格上的曲面设计方法

提出一种在不规则网格上构造曲面的方法.其基本思想是,通过均匀双三次B样条基函数的分解和子基函数的分类,将B样条曲面方法推广到任意四边形网格.给定一个任意四边形控制网格,首先对每个控制点构造一个基函数;所有控制点加权组合形成整体曲面.构造的曲面是分片双三次有理参数多项式曲面.此方法可以看成是均匀B样条曲面构造方法的扩展,如果控制网格是规则四边形网格,那么构造得到的曲面与均匀双三次B样条曲面是一致的.最后,实例证明此方法能够有效地构造曲面.     

基于最优模糊PID温度控制方法研究

针对某智能大厦空调的温度控制系统,引入了一种新的模糊推理方法,设计了模糊PID控制器.该模糊推理方法将优化和反馈的思想引入推理过程中,依据不同的优化指标进行推理,使推理过程更为有效,论文给出了应用该推理方法的具体过程.以建立起的温度系统模型为基础,设计了基于最优模糊推理的温度系统模糊PID控制器,进行了仿真研究,仿真结果和实际运行表明了该控制方法具有强鲁棒性和良好控制品质.     

声学参量换能器阵及其测试系统设计

根据声学参量阵原理,设计了一个3×3的九元矩形换能器阵及其测试系统,并在空气进行验证性实验;系统包括正弦信号产生电路、信号控制电路、功率放大电路以及回波信号接收电路等,辅以LabVIEW平台,实现正弦信号和脉冲控制信号的产生,发射信号时间长度控制以及功率放大,并最终驱动换能器阵;实验表明,当有85kHz和90kHz的正弦信号产生时,系统各部分均能正常工作,能够听到天花板处有声响,且回波信号中含有5kHz的频率成分,即证明换能器阵及其系统的设计均是可行的.     

AutoCAD的尺寸驱动技术的探讨

AutoCAD是一种人机交互的绘图软件,本身并不具备参数化绘图功能,更不具备尺寸驱动功能,但用户可以利用其所提供的强大的二次开发语言AutoLISP、VisualLISP、VBA开发完全个性化的、性能更为优越的、具有尺寸驱动功能的参数化绘图软件。