排序方式: 共有111条查询结果,搜索用时 468 毫秒
31.
The reduction approaches are presented for vibration control of symmetric, cyclic periodic and linking structures. The condensation of generalized coordinates, the locations of sensors and actuators, and the relation between system inputs and control forces are assumed to be set in a symmetric way so that the control system posses the same repetition as the structure considered. By employing proper transformations of condensed generalized coordinates and the system inputs, the vibration control of an entire system can be implemented by carrying out the control of a number of sub-structures, and thus the dimension of the control problem can be significantly reduced. 相似文献
32.
33.
34.
光纤布喇格光栅器件应力疲劳评价理论研究 总被引:3,自引:2,他引:1
光纤布喇格光栅器件应力疲劳特性严重影响着光纤光栅应变传感器的长期可靠性,为了评估光纤光栅器件的应力疲劳特性,分析了光纤光栅应变传感器的封装结构对疲劳评价的影响,并以表面直接粘接的简化模型评估了光纤光栅器件的应力疲劳特性.从简化模型的基本力学与光学特性出发,提出以光谱特性的边模抑制比和带宽作为评价光纤光栅器件疲劳的指标体系,以传感特性的灵敏度、线性度和应变传递效率作为评价粘接层疲劳的指标体系.设计了基于等强度梁的光纤光栅器件加速疲劳实验,疲劳的应力幅度为500微应变,频率为18赫兹;1000万次疲劳实验后,三支光纤光栅的带宽平均增加2.07%,平均应变传递效率和平均灵敏度分别下降4.5%和3.9%,实验结果说明提出的指标体系能有效地区分粘接层和光纤光栅的疲劳,从而验证了该评价理论的可行性. 相似文献
35.
为研究影响倒装LED芯片电流密度均匀分布的因素, 建立了芯片的三维有限元电学模型, 采用COMSOL有限元仿真方法, 分析了芯片尺寸、电极结构、电流注入点对倒装LED芯片电流分布均匀性的影响, 并对相关机理进行了探讨. 研究结果表明, 芯片尺寸的增加扩展了电流的横向传输路径与横向电阻, 使LED芯片电流分布的不均匀性呈指数型恶化; 叉指式电极结构可有效缩短电流传输途径, 增加叉指电极数目有利于电流均匀性的提高; 通过在块状电极上合理设计电流注入点可缩短电流传输路径, 显著提高电流的均匀性. 相似文献
36.
为了提高声光移频器的性能,对其内部声光晶体(AOC)和压电超声换能器(PZT)电极之间的位置失配特性进行研究,并深入分析AOC和PZT电极之间几类不同的几何装配错位关系.通过构造AOC与电极失配的三维有限元模型,在不同轴向装配错位的条件下对AOC中的超声波声场进行仿真分析.根据超声波的声场分布特性,可以发现几何装配错位会导致AOC内部形成不发生声光相互作用的区域,并揭示此区域长度与错位量的关系.通过分析声光相互作用区与不发生声光相互作用区之间的光学界面,发现位置失配会在输出光中发生双光束干涉效应,其对实际光学系统的输出会产生影响.基于双光束干涉原理搭建一种测量不发生声光相互作用区域长度的实验系统,所得结果证明理论分析的合理性. 相似文献
37.
38.
提出一种基于径向基函数神经网络模型来重构蜕化的光纤光栅应变传感器的方法.以结构健康监测系统中应变测量系统的光纤光栅应变传感器之间关联分析为基础,依据径向基函数神经网络强大的函数逼近能力,利用关联度高、运行良好的应变传感器去重构蜕化的应变传感器,保证重构的应变传感器与蜕化传感器有较高的数据准确度.实验结果证实了该方法在理论和实践上的精确性和可行性. 相似文献
39.
Laser-produced plasma helium-like titanium Kα x-ray source and its application to Rayleighben-Taylor instability study 下载免费PDF全文
Several experiments are performed on the ShenGuang-II laser facility to investigate an x-ray source and test radiography concepts. X-ray lines emitted from laser-produced plasmas are the most practical means of generating these high intensity sources. By using a time-integrated space-resolved keV spectroscope and pinhole camera, potential helium-like titanium Kα x-ray backlighting (radiography) line source is studied as a function of laser wavelength, ratio of pre-pulse intensity to main pulse intensity, and laser intensity (from 7.25 to ~11.3× 1015 W/cm2). One-dimensional radiography using a grid consisting of 5 μm Au wires on 16 μm period and the pinhole-assisted point projection is tested. The measurements show that the size of the helium-like titanium Kα source from a simple foil target is larger than 100 μm, and relative x-ray line emission conversion efficiency ξx from the incident laser light energy to helium-like titanium K-shell spectrum increases significantly with pre-pulse intensity increasing, increases rapidly with laser wavelength decreasing, and increases moderately with main laser intensity increasing. It is also found that a gold gird foils can reach an imaging resolution better than 5-μm featured with high contrast. It is further demonstrated that the pinhole-assisted point projection at such a level will be a novel two-dimensional imaging diagnostic technique for inertial confinement fusion experiments. 相似文献
40.