一类多体系统非完整运动最优规划的拟牛顿算法

研究带有非完整约束的一类多体系统运动规划问题。多体系统中的非完整约束通常是由不可积的速度约束或不可积的守恒律引起。在系统动量和动量矩守恒情况下,动力学方程降阶为非完整形式约束方程,系统的控制问题可转化为无漂移系统的非完整运动规划问题。文中首先导出具有多体开链系统的非完整运动模型。利用最优控制理论和最优化技术,采用输入参数化的方法将连续的最优控制问题转化为离散的最优控制问题,提出一种非完整多体系统运动规划的拟牛顿算法。最后将该方法用于自由漂浮的空间三连杆机构,仿真结果验证了该方法的有效性。     

微球动态涂敷状态实时监测光学系统的设计

 介绍了一种可用于实时监测直径0.2～1.0 mm激光核聚变靶球涂敷状态的光学系统的设计，系统采用环形LED照明系统以适合特殊的照明要求，用Petzval型物镜使500 mm处的微球清晰成像于CCD像面上，CCD输出的图像电信号经图像采集卡转换成数字信号，最后该数字信号由计算机进行处理，实现了系统对靶球膜层涂敷作业的自动监控，大大提高了涂敷效率。所设计的系统轴上点最大弥散斑直径为12.6 mm,轴外最大弥散斑直径为15.8 mm，整个视场的像质比较均匀,分辨率较高，对于波长522 nm的光线，场曲和畸变分别小于15 mm和0.012%，像质优良。     

光学元件狭缝柔性调节机构的设计与分析

设计了一种狭缝柔性结构的光学元件调节机构,使光学元件在具备较高调节精度的同时,保持较高的导向精度。采用弹性力学应力函数法分析了狭缝柔性结构的刚度,以径向刚度与轴向刚度的比值为目标函数,对狭缝柔性结构尺寸参数进行了优化,在不超过柔性结构材料屈服应力等约束条件下,刚度比最优值达到1 573.6,较大的刚度比值可以减小调节机构的耦合位移,从而提高机构的导向精度。该结构加工装配方便,可实现三自由度(θx-θy-Z)调节。对优化后的柔性结构进行仿真分析,结果表明:径向刚度与轴向刚度比值的仿真值为1 660.4,解析值与仿真值误差为5.23%,证明了刚度分析方法的有效性。优化后的结构,轴向调节行程为2.09 mm,绕x轴偏转角度调节行程为±16.6 mrad,绕y轴偏转角度调节行程可达到±14.4 mrad,满足光学元件调节的大行程要求。     

东亚地区大气环流的季节划分及其时空变化特征

利用NCEP-DOE Reanalysis 2 1979-2009年位势高度场、温度场、湿度场和风场逐日再分析资料,采用考虑面积权重的区域多要素最优分割法,对东亚地区大气环流的季节进行划分,并分析了四季起始时间的时空变化特征.研究结果表明:1)东亚地区春季最早始于中高纬地区的平流层和副热带的对流层中下层;夏季最早始于中高纬的平流层和副热带、中纬度地区的对流层中上层;秋、冬季开始最早的地区集中在东亚地区东部和东北部的对流层中低层,以及中高纬的平流层. 2)季节变化与环流形势密切相关,且对流层各个层次的夏季和冬季起始时间的分布均有较好的垂直一致性,平流层与对流层各季节起始时间分布有较大的差异性,平流层中层和下层也并不一致. 3)华北地区四季平均起始时间距平序列的逐年演变特征表明近30年该地区出现了6个四季起始时间异常偏早的年份,与El Niño活跃年份相一致,反映了海温等外强迫对大气环流季节变化的影响. 关键词： 季节划分 东亚地区 区域多要素最优分割法     

基于聚类和最佳指数的快速高光谱波段选择方法

最佳指数法是常用的高光谱图像数据波段选择方法,但存在运算时间过长的问题。运用K-means聚类算法,对最佳指数方法进行了改进,提出了聚类最佳指数法,并进行了一系列伪装目标识别的对比实验。实验结果表明,与最佳指数法相比,改进后的方法在保证目标分类精度的前提下,运算速度提高了数十倍;与单纯使用K-means聚类运算相比,不仅运算时间缩短,而且分类精度有所提高。利用改进算法能够在伪装环境下更加快速有效地识别目标。     

基于旋转式反射镜的飞行视觉系统设计

在MEMS麦克风贴片工艺中,真空吸嘴吸取MEMS芯片以后需要进行芯片位姿的精确校正。为实现高速高精度贴片功能,提出了一种基于旋转式反射镜的飞行视觉系统,该方案利用齿轮齿条将吸嘴的升降运动转化为反射镜的旋转运动,通过设计齿轮参数,实现反射镜不干涉吸嘴的拾放功能。当反射镜旋转到与水平位置夹角呈45°时,视觉系统可以获得MEMS芯片的静止的清晰图像,CCD相机采集一幅图像后,在贴片头飞行的过程中,控制系统完成MEMS芯片的位置和角度的校正。实验结果表明,该系统可以获取高质量MEMS芯片图像。该系统结构简单紧凑,成像无失真,不限制贴片头的运动轨迹,显著提高了MEMS芯片的贴片质量和贴片效率,可广泛地应用于贴片机系统中。     

GA-based optimization of a MIMO ANC system considering coupling of secondary sources in a telephone kiosk

In this paper a multi-input, multi-output (MIMO) active noise control system with the aim of global reduction of broadband noise in a telephone kiosk is addressed. The model selected for this optimization problem is the acoustic environment of an enclosure taking into account the effect of coupling of secondary sources used for control purpose. This optimization involves finding the best locations for loudspeakers and microphones inside the enclosure as well as optimizing the control signals considering secondary source coupling.Previous results show that in order to be able to reduce acoustic noise globally inside the enclosure, the frequency range of 50-300 Hz must be selected for control purpose. The mean of acoustic potential energy of the enclosure, when excited in this frequency range, is adopted as a performance measure. This performance index is penalized with the power of the signal required to excite secondary loudspeakers, in order to avoid placements that may need high voltage power amplifier for a desired performance. To find the solution of this problem, i.e. the global minimum of the performance index, several genetic algorithms are proposed and compared. In order to attain the best achievable performance in reaching the global minimum, the parameters of these genetic algorithms are tuned, and used for optimization purpose. Numerical simulations of the acoustical potential energy as well as the sound pressure at different heights of the kiosk, when active noise control (ANC) system operates, confirm the optimality of the locations proposed by the genetic algorithm.     

框架结构主动控制最优时滞研究

在结构振动主动控制中,时滞的大小对结构控制能量和响应均产生影响。在允许时滞的范围内,把结构控制能量和响应作为目标函数,数值仿真发现目标函数随着时滞的变化呈现曲线状态,这说明存在最优时滞。在目标函数处理方面,考虑到控制能量和响应数量级不一致,本文采用了无量纲化处理。同时,考虑到地震波的随机性,本文还推导了含控制力的改进的随机Newmark方法。最后给出了一个计算实例。实例表明本文所提出的方法是有效的。     

Load optimal design for a primary test stand facility based on a zero-dimensional load model

In order to couple the numerical simulation of a primary test stand driver with an optimal load design, a zero-dimensional wire array load model is designed based on the Saturn load model using PSPICE, which is an upgraded version of the Simulation Program with Integrated Circuit Emphasis (SPICE) designed by the ORCAD Corporation to perform circuit simulations. This paper calculates different load parameters and discusses factors influencing the driving current curve. With appropriate driving current curves chosen, further magneto-hydrodynamic calculations are carried out and discussed to provide the best results for experiments. The suggested optimal load parameters play an important role in experimental load design.     

A multi-parametric programming approach for multilevel hierarchical and decentralised optimisation problems

In this paper, we outline the foundations of a general global optimisation strategy for the solution of multilevel hierarchical and general decentralised multilevel problems, based on our recent developments on multi-parametric programming and control theory. The core idea is to recast each optimisation subproblem, present in the hierarchy, as a multi-parametric programming problem, with parameters being the optimisation variables belonging to the remaining subproblems. This then transforms the multilevel problem into single-level linear/convex optimisation problems. For decentralised systems, where more than one optimisation problem is present at each level of the hierarchy, Nash equilibrium is considered. A three person dynamic optimisation problem is presented to illustrate the mathematical developments.