新型磁悬浮运动平台力学分析与控制

为了设计最佳控制参数对两级磁悬浮运动系统进行稳定可靠的悬浮控制,运用动力学时域和频域分析理论对系统进行分析.经理论推导将系统差动式结构电磁力模型等效为质量-弹簧-阻尼二阶系统.并运用ANSYS软件对等效模型进行刚度和瞬态响应分析,由仿真结果确定了系统最佳等效刚度和阻尼比,并以此为依据设计系统PID控制参数?在仿真分析指导下,经反复调试,实现了两级磁悬浮运动平台的稳定可靠悬浮.实验结果验证了理论研究和仿真分析的正确性.     

“激光微纳制造”专题前言

<正>随着高端制造需求的日益增加,传统的制造手段已远远不能满足航空航天和电子制造等领域中精密零部件(如飞机发动机、惯性导航和半导体芯片等)的精细制造需求。因此,激光微纳制造技术应运而生,并始终矗立于基础科学前沿及制造领域尖端位置,成为国家战略新兴产业发展的重大关键技术之一,对我国的国防安全与国民经济建设起到了愈来愈重要的作用。     

Influences of polishing on return loss of optical fiber connectors

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.     

单自由度电磁轴承系统的起动性能分析

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．     

带钢表面振纹的工业试验与发现

对某平整机生产的带钢表面横振纹进行了一系列试验研究 ,发现带钢表面振纹与系统的自激振动强相关 ,此种振动源于部分流体润滑与粘滑兼存的辊缝界面     

Efficient approach for dynamic simulation of complex fluid networks in frequency domain

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｍａｔｈｅｍａｔｉｃａｌｍｏｄｅｌｉｎｇａｎｄｄｙｎａｍｉｃａｎａｌｙ ｓｉｓｏｆｆｌｕｉｄｔｒａｎｓｍｉｓｓｉｏｎｎｅｔｗｏｒｋｓｈａｖｅｂｅｅｎｔｈｅｉｎｔｅｒ ｅｓｔｉｎｇｒｅｓｅａｒｃｈｔｏｐｉｃｆｏｒａｂｏｕｔ 50 ｙｅａｒｓ .Ｔｈｅｗｉｄｅｖａ ｒｉｅｔｙｏｆａｐｐｌｉｃａｔｉｏｎｓｏｆｆｌｕｉｄｎｅｔｗｏｒｋｓ ,ｓｕｃｈａｓｆｌｕｉｄｐｏｗｅｒｃｏｎｔｒｏｌ ,ｆｌｕｉｄｓｉｇｎａｌ ｐｒｏｃｅｓｓｉｎｇ ,ｐｅｔｒｏｌｅｕｍｔｒａｎｓｍｉｓｓｉｏｎ ,ｈｙｄ…     

基于小波变换的轴心轨迹特征提取

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     

熔融拉锥光纤耦合器熔锥区的红外光谱研究

以不同拉锥速度制作的耦合器为样品,用显微红外光谱仪测试了其熔区和锥区。实验发现:在1100cm-1和810cm-1左右有两个明显的特征峰;1100cm-1特征峰在锥区的波数最高,熔区次之,裸光纤最小;随着拉锥速度的增大,1100cm-1特征峰移向高波数;150μm/s的拉锥速度下制作的耦合器熔锥区析晶少,微观结构畸变小,性能最优。     

2×2单模光纤耦合器的改进控制方法

探讨了熔融拉锥过程中工艺参数的优化设计,提出了一种在拉伸到一个较小预定分光比之后只进行加热熔融的耦合器制造的新方法,通过理论分析了其可行性,并通过VC 程序实现了该工艺的控制过程.通过大量的实验表明,该种方法制造的2×2单模光纤耦合器的性能有显著提高,而且可靠性明显优于普通熔锥型光纤耦合器.因此这种方法是一种耦合器的改进型制造方法.     

Relationship between rheological manufacturing process and optical performance of optical fiber coupler

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.