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.     

Rheological behavior of continuous roll casting process of aluminum alloy

The rheological behavior of aluminum alloy and its influencing factors in physical simulation of continuous roll casting process were studied by using a Gleeble-1500 thermal-mechanical simulation tester with a set of special clamp system. The relationships between the flow stress and the strain rate in the deformation process of simulating roll casting experiment were obtained. The results show that four different characteristic stages exist in the temperature range of the whole rheological process. The first occurs when the temperature is higher than 600℃, which belongs to the creep deformation stage; the second occurs when the temperature lies in the range of 500 - 600℃, and it can be regarded as the high temperature and low stress level deformation stage; the third occurs when the temperature decreases to the range of 300 - 500℃, it is considered to be the middle stress level deformation stage; the last occurs when the temperature is less than 300℃ and the strain rate is less than 1.00 s^-1 , it belongs to middle stress level deformation stage. But when the strain rate is larger than 1.00 s^-1, it belongs to the high stress level deformation stage. And the relative constitutive models suitable for the four different stages of continuous roll casting process were established through multivariate linear regression analysis of the experimental data.     

复杂流体网络动态建模与仿真新方法

对流体元件常规传递矩阵模型进行了改进,引入了一种处理节点边界条件的简便方法,提出了复杂流体网络在各种终端边界条件和多扰动条件下的动态建模方法。将频谱函数与时域响应的傅里叶逆变换转换为傅里叶正变换,利用著名的ＦＦＴ算法实现了复杂流体网络的时域仿真计算,为大规模液压和气动网络的频率特性计算及时域动态仿真提供了全新的手段,有关算例及相关试验验证了本方法的正确性。     

一个复杂非线性液压系统的建模和仿真

复杂、非线性物理系统的建模和仿真一直是很令人棘手的问题。本文利用键合图、大系统分析法和耦合理论对一个实际液压系统进行了分析,并以实测进行了验证,表明将三种方法结合使用,能有效、方便地处理复杂、非线性系统的建模和仿真问题。     

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…     

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     

超塑Al-Mg-Li合金的显微组织与织构特性

采用一种新型形变热处理方法制备细晶Al-Mg-Li合金板材,研究静态再结晶退火对合金板材晶粒组织及超塑变形行为的影响。结果表明,晶粒尺寸、形状和织构的分布沿板材法向方向存在明显不同;表面层的晶粒组织细小、等轴,含有旋转cubeND{001}（310）取向;中心层具有粗大、长条状晶粒,含有a取向线的织构组分。随着再结晶温度的升高,整个板材的晶粒尺寸长大,中心层晶粒纵横比减小,表面层织构强化而中心层织构弱化,超塑性伸长率下降。升高再结晶温度导致整个板材内的旋转cubeND{001}（310）织构组分强化而a取向线的织构弱化。分析了不同温度下再结晶织构的形成机制。     

热超声倒装键合过程中的非线性动力学行为

在作为微器件电气互连主要手段的热超声键合工艺中,微细键合区域内金属变形/变性/互连所需的能量,来自于超声波功率源通过换能系统所施加的微幅压剪动载.对热超声倒装键合过程的研究说明,PZT换能系统在热超声倒装键合工艺过程中的非线性动力学行为,如换能系统启动后的初值敏感性和不确定性,键合工具与换能杆之间的不稳定动力耦合,倒装芯片运动的奇异相轨线等,是深入研究键合机理以及提高工艺可靠性的重要关键.     

CVC 四辊轧机有载辊缝解析模型

运用梁的弯曲变形理论,基于工作辊和支撑辊之间的变形协调关系,直接导出了辊间压力分布及辊间弹性压扁系数的解析表达式,从而较精确地求出轧辊的弹性变形,并由此得到较精确的辊缝解析解。     

TBM刀盘地质适应性设计方法及其应用

刀盘是全断面硬岩掘进机(TBM)的核心部件,其结构的地质适应性是决定TBM掘进效率的关键因素。根据TBM刀盘制造企业设计的实际需要,制定了刀盘设计基本流程,结合掘进地质条件、刀盘结构参数和掘进参数,建立了刀具布置、开口、盘体设计等关键参数计算模型,提出相应的TBM刀盘地质适应性设计方法。将TBM刀盘设计方法应用于某供水工程,对该工程所用TBM的刀具布置参数、刀盘驱动性能与掘进参数以及刀盘结构参数进行地质适应性设计,并对设计方案进行了力学性能和出渣性能仿真分析。研究结果表明,刀盘设计方法能有效实现刀盘结构、刀具布置以及相关掘进参数地质适应性设计,所设计的刀盘力学性能满足施工要求。目前该刀盘在引水工程中累计已掘进12 km,工作状态良好。