共查询到20条相似文献,搜索用时 562 毫秒
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针对地铁小半径曲线上普遍存在的钢轨波磨问题,基于轮轨间粘滑振动导致波磨形成的机理,利用MATLAB/Simulink建立了一个集轮轨耦合动力学、轮轨滚动接触力学模型以及Archard材料磨损模型为一体的单轮对轮轨曲线通过仿真模型进行研究。仿真结果表明,曲线半径越大,钢轨波浪型磨耗越不易产生。该结果与实际小半径曲线上波磨频发相符合,证明了该模型的正确性。最后,利用该模型进一步分析了车辆载重与曲线超高对波磨的影响。 相似文献
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为研究轮毂电机对车辆平顺性的影响,文章建立了1/4车辆二自由度振动系统模型和随机路面输入模型,以MATLAB/Simulink为仿真平台建立了相应仿真模型,通过仿真得到了不同非簧载质量情况下车身加速度、车轮相对动载荷以及悬架动挠度对路面速度激励的响应.最后,分别从频域和时域角度对振动系统响应进行分析,结果表明,随着非簧... 相似文献
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根据电磁场模场匹配理论,分析了自由空间光-布拉格光纤的耦合效率.通过对空间光-布拉格光纤耦合效率的计算可以知道,耦合效率与布拉格光纤纤芯半径、焦点光斑光腰半径和纤芯波矢有关.通过优化合理选择空间光聚焦后光腰半径与布拉格光纤纤芯半径以及纤芯波矢可以有效提高耦合效率.本文还对外界振动造成耦合透镜与布拉格光纤对接不正而对空间光-布拉格光纤耦合效率影响进行了分析.这对光纤激光雷达系统以及空间光通信系统的空间光-布拉格光纤耦合效率分析具有极其重要的参考价值. 相似文献
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针对应用于可调谐二极管激光吸收光谱(TDLAS)技术研究中的一种简单的集成化光学系统,利用ANSYS有限元分析方法,建立系统有限元模型,分析了系统模态和谐响应特性;通过振动台实验测试了系统结构的动力学特性,获得系统结构在不同动力载荷作用下的幅频曲线。结合数值模拟和测试结果,分析获得系统抗振性能,给出了系统所能承受的环境振动频率范围。结果表明:该光学系统在900 Hz以内的振动环境下具有良好的抗振性能,可以应用于现场测试诊断。 相似文献
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Zhang T.H. Zhang L.Z. Yu X.Y. He R. Hu Z.J. Xu J.J. 《Quantum Electronics, IEEE Journal of》2009,45(2):132-137
The coupling between forward propagating wave and backward propagating wave of photorefractive surface waves (PR SWs) along the surface of photorefractive crystals (PRC) with periodic corrugations is studied for the first time. The influences of depth and period number of periodical corrugation structures on the coupling between the forward propagating PR SW and backward propagating PR SW are discussed. Especially the influence of nonlinearity on the coupling is studied for the first time. The reflectivity and transmissivity of PR SWs are calculated numerically using coupled-mode theory. The results are significant for the design of integrated optical device utilizing photorefractive surface waves. 相似文献
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N. S. Ginzburg V. Yu. Zaslavskii A. M. Malkin N. Yu. Peskov A. S. Sergeev M. Tumm 《Journal of Communications Technology and Electronics》2009,54(9):1015-1026
A comparative analysis of the selective characteristics of Bragg resonators with various types of periodic corrugation is
performed. In the simplest case of the azimuthal symmetric corrugation in a highly overmoded resonator (a large ratio of the
perimeter to the wavelength), the Q factors of modes with different numbers of azimuthal variations are almost equal and the mode frequencies are close on the
scale of the gain band of electron flow. A certain rarefaction of the mode spectrum can be attained using the helical corrugation
when the traveling wave is coupled with the whispering-gallery modes and the frequency interval between the high-Q modes of the resonator with different azimuthal indices is determined by the interval between the critical frequencies of
the whispering-gallery modes. The doubly periodic corrugation employed in the 2D Bragg resonators at the same (as in the case
of the helical corrugation) intermode distance allows the Q-factor selection of a single azimuthal symmetric mode. The analysis is based on the method of coupled waves and the direct
numerical simulation using standard codes. 相似文献
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提出3cm双频两段式同轴相对论返波振荡器,用粒子模拟软件对其结构和电磁参数进行分析研究,优化得到的结构参数为第一、二段分别为10和4个周期数,周期长度分别为0.5cm、0.73cm,波纹幅值分别为0.13cm、0.21cm,平均半径2.9cm,同轴间隙为2.1cm。实验结果表明在环形相对论电子注电压为510kV,电流为9.4kA,引导磁场为0.7T的条件下,器件得到了3cm波段稳定的高功率双频微波输出,其平均功率约为0.75GW,平均功率效率为15.6%。 相似文献
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Analysis of a novel semiconductor laser structure designed for obtaining wide tuning range along with high speed modulation response is presented. The laser consists of a composite cavity structure with two active (gain) sections. One of the sections has a grating corrugation while the other is flat. A detailed round-trip analysis is combined with the rate equations, which include sublinear gain/carrier relation, to perform steady-state and small-signal analysis. It is shown that the biasing (dc) condition of the different sections plays a critical role in the determination of the dynamic response of the device. In addition, we show that the gain-lever effect can be utilized for a considerable enhancement of the frequency modulation (FM) response. Other critical structural parameters such as the grating coupling coefficient and device geometry are discussed 相似文献
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We have studied the effect of the interface corrugation on the Raman response of (113), (112), (331) and (012)-oriented AlAs/GaAs superlattices. The phonon frequencies and displacements have been calculated using the bond charge model and a supercell approach, and the Raman spectra have been calculated using the bond polarizability model. In (113)-oriented superlattices, the corrugation would give rise to an additional mode coupling and an enhancement of the phonon confinement. The magnitude of these effects and the consequent modifications on the Raman spectra would be quite different for the two interface structures proposed in the literature. For the (112), (331) and (012) superlattices, the modifications induced by the in-plane periodicity would be weak, even in the case of ultrathin superlattices. This is due to the very small height of the interface corrugation and also because the proposed lateral periodicity would not induce any significant mode coupling. 相似文献
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胶合板声发射信号的小波包特征提取及神经网络模式识别 总被引:1,自引:0,他引:1
为识别胶合板的不同损伤类型,将小波包时频分析与能量谱相结合,提出基于时频和频段能量占比的胶合板损伤声发射信号特征提取方法。研究得出胶合板基体开裂信号以膨胀波和弯曲波模式并举,频谱较宽,能量主要集中在小波能量谱的第一、二、三、四和七频段;分层信号频率单一,幅值较高,并以膨胀波为主;纤维断裂主要以弯曲波模式为主,频率较低;脱胶信号波形为膨胀波和弯曲波的混合型,以弯曲波为主,能量多集中于第一、二、三、四频段。用小波包提取的能量占比作为由BP神经网络构成的智能化模式分类器的输入样本,对4种声发射信号进行识别,正确率达到92.6%。 相似文献
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针对真空电子太赫兹辐射源的发展需要,本文分析和设计了一种微型正弦波纹慢波结构。利用三维电磁仿真软件研究并分析了其高频特性,并对主要结构参数进行了优化,给出了不同参数下的色散特性和耦合阻抗。仿真结果表明:增加波纹深度可降低电磁波相速,同时增大耦合阻抗;缩短周期长度可提高工作频率;增大横截面宽度可降低相速;降低电子注高度可提高耦合阻抗等。 相似文献
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