Metal coating of fiber Bragg grating and the temperature sensing character after metallization

In this study, the fiber Bragg grating (FBG) was metallized with a nickel coat using an electroless-electro plating method. Under the optimum conditions, the surface of chemical plating and electroplating coat are smooth and compact, there is not any visible defect in the cross-section. The effects of the nickel coat on the properties of the fiber sensor were studied. With this plating method, the FBG can be well protected and its sensing properties can be changed. When the temperature is changed, a thermal stress between the metal coat and the fiber will be induced because of the thermal expansion coefficients difference. The thermal stress influence on the temperature sensing properties of the metalized FBG was analyzed, and a physical-mathematical model for FBG temperature sensing was presented. Experimental results show the mathematical model is feasible to explain the mechanism of temperature sensitivity enhancement for metalized FBG.     

基于Sagnac干涉的光纤对冲床脉动电流计量技术的研究

基于Sagnac干涉原理的全光纤光电互感器具有响应特性好、精度高、安全性好的特性,是解决脉动电流测量的新技术之一。以J21-40T普通冲床为研究对象,应用光波的偏振性和法拉第磁光效应理论,探究了全光纤光电互感器测量冲床脉动电流的工作机理。通过对Sagnac调制技术的全面分析,设计了系统框图。借助测量数据,阐述了测量重复性、温度变化、1／4波片、Verdet常数误差。研究结果表明：这一技术可以普遍用于冲床脉动电流的准确测量,是一种有效的大电流计量技术。     

光纤AM CATV外调制发射技术

就光纤AMCATV外调制发射机的关键问题，即光源的选择、调制器的选择、非线性补偿、限幅失真抑制及CSO和CTB的闭环控制进行了较全面的论述。     

基于光纤光栅传感器高压开关柜温度监测系统设计

本文针对高压开关柜温度监测问题,提出了一种基于光栅原理的温度监测系统。文章首先阐述了高压开关柜温度监测在电力系统中的重要性,其次对国内外目前的监测手段进行简要介绍,再次阐述了光线光栅的测温原理,最后对设计的光纤光栅温度监测系统进行阐述。本文依据光纤光栅传感器的测温原理,对高压开关柜温度监测问题进行了有益探索,对实际应用具有一定的指导意义。     

基于单元平均应变的结构多损伤静态识别

利用长标距布喇格光纤光栅（FBG）传感器,可以测量结构一定长度的平均应变。在介绍单元平均应变的基础上,采用单元平均抗弯刚度和广义单元平均中性轴高度作为识别参数,通过工字形悬臂钢梁和简支钢梁的多损伤数值模拟进行了验证,说明基于单元平均应变的结构静态损伤识别方法是可行的。     

碳纤维在土木工程加固中的应用研究

碳纤维补强加固结构技术是近年来在国内外快速发展的一种结构补强加固新技术,由于碳纤维材料具有优良的物理力学性能,良好的粘结性、耐久性等特点,利用碳纤维加固混凝土结构,能有效地提高混凝土结构的强度、刚度、耐久性。主要介绍了碳纤维增强材料加固补强混凝土结构的应用情况和研究现状,并对其应用前景进行了展望。     

基于Moldflow的汽车仪表板本体骨架变形分析及结构改进

以某新开发车型仪表板本体骨架为研究对象,采用成熟的注塑成型有限元分析软件Moldflow,基于ARD-RSC长玻璃纤维分析模型,对本体骨架的变形量进行分析,得出了发泡区域的变形量,结果表明,发泡区域变形量不满足发泡模要求的变形小于5mm.根据分析结果,对比不同翘曲效应对总体变形的影响,找出了影响发泡区域变形的主要原因为...     

Development of a monitoring and warning system based on optical fiber sensing technology for masonry retaining walls and trees

Hong Kong has a long history of applying masonry retaining walls to provide horizontal platforms and stabilize man-made slopes. Due to the sub-tropical climate, some masonry retaining walls are colonized by trees. Extreme weather, such as typhoons and heavy rains, may cause rupture or root failure of those trees, thus resulting in instability of the retaining walls. A monitoring and warning system for the movement of masonry retaining walls and sway of trees has been designed with the applicatio...     

椭圆芯保偏光纤模间干涉的研究

对椭圆芯保偏光纤的模间干涉现象进行了仿真研究,得到了其干涉输出光强分布同模间相位差之间的关系.将一种椭圆芯保偏光纤进行等面积矩形变换后,通过马卡梯里近似方法对两个低阶模式LP01模和LPeven11模的传输特性及传播常数进行了数值计算,得到了归一化传播常数和归一化截止频率之间的关系.通过实验得到了两个模式之间干涉模斑远场图样,表明椭圆芯保偏光纤的模间干涉特性可以应用于应力、电压等的测量.模间干涉将传感臂和参考臂集于一根光纤中,具有很好的抗环境干扰能力.     

Special Apodized Fiber Bragg Grating for Flat—top Band—pass Reflectivity Filter

The characteristics of special apodized fiber Bragg grating (FBG) in flat--top pass--band as reflectivity filter are presented. This special apodized FBG was designed by the particle swarm optimization algorithm. Compared with conventional apodized FBG, the special apodized FBG presented was more robust in the flat—top pass——band characteristic even if the strength of grating is very week. This technology is very interesting in designing the filter for wavelength division multiplexing system.