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With Al2O3 and SiO2 as polishing medium, under different polishing conditions, e.g. with different polishing pressure, polishing time and polishing fluid, the influences of polishing treatment on the return loss of optical fiber connectors were investigated. The return loss of optical fiber connectors is 32-38 dB before polishing. The resuits show that dry polishing(i, e. no polishing fluid) with Al2O3 has less influence on return loss of optical fiber connectors, while dry polishing with SiO2 reduces return loss to about 20dB because of the end-face of optical fiber contaminated. The wet polishing(i, e. using distilled water as polishing fluid) with Al2O3 or SiO2 can increase return loss to 45-50dB, but wet polishing with Al2O3 may produce optical fiber undercut depth of 80-140nm. Wet polishing with SiO2 should be preferentially selected for optical fiber connectors and polishing time should be controlled within 20-30s. 相似文献
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在建立电磁轴承数学模型的基础上,设计了基于H∞控制理论的鲁棒控制器,研究起动时系统的响应、受扰情况及控制电流和转子位移之间的关系,讨论起动性能的影响因素.实验表明,H∞控制器作用下的电磁轴承系统具有良好的起动特性、鲁棒性和干扰抑制效果. 相似文献
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Through theoretical analysis and experiments, the viscoelastic mechanical model of optical fiber coupler in the process of fused biconical taper was established, and the numerical analysis in non-uniform temperature field was made. The results show that the rheological parameters, such as drawing speed and fused temperature, have a tremendous influence on stress distribution and performance of optical fiber coupler, especially the influence of fused temperature. The change of fused temperature by 5 ℃ can lead to the change of the maximum stress by 30% and stress difference by 20% in the same cross section. The change of temperature gradient by 3% can result in the change of stress difference by 90%. In the present condition of rheological technology, rheological defects such as crystallizations and microcracks are easy to generate in the optical fiber coupler. 相似文献
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高速轧机工作界面的负阻尼特性 总被引:4,自引:0,他引:4
轧制界面作为轧制过程的工作界面,其动力学特性对轧机振动有决定性影响,作者分析了动态情况下轧制界面上的金属塑性流动、界面摩擦学、工作辊运动等行为机理及其耦合特性;通过研究工作辊振动对界面润滑膜厚的影响以及界面动态摩擦学行为对金属塑性流动的影响,建立了轧制界面的动力学模型,并对轧制界面的阻尼特性进行了数值仿真,研究结果表明:在混合润滑条件下,轧制界面因润滑膜厚动态变化可产生负阻尼,界面阻尼的大小与轧制工艺、轧辊表面状态、润滑剂特性等参上关,为解释轧机自激振动机`理控制或消除轧机颤振提供了理论基础。 相似文献
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基于小波变换的轴心轨迹特征提取 总被引:8,自引:0,他引:8
回转机械的轴心轨迹包含着反映其运行状态的丰富信息,但由于各种噪声干扰严重,使轴心轨迹非常杂乱,难以从中得到有用信息。本文将小波变换用于提纯轴心轨迹,剔除干扰,提取故障特征,取得了良好的效果 相似文献
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铝板带材轧机振动测试分析 总被引:1,自引:2,他引:1
针对某铝板热轧机严重振动问题,测试了轧辊垂直振动、主传动系统扭振和液压压下系统压力与主电机电枢电流等参数,分析了其振动特点。采用拟三维有限元模型分析了同系统的固有特性。测试与分析表明,铝板热轧机振动的主要形式是强迫振动,主要振因来源于工作辊轴承和支承辊轴承特征振动。 相似文献
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H∞控制理论在磁悬浮球系统中的应用 总被引:1,自引:0,他引:1
本文将H∞控制理论用于磁悬浮球系统,应用混合灵敏度方法设计了控制器,并进行了实验验证。 相似文献