光纤电焊电流测量技术研究

针对直流逆变电阻焊机焊接电流精确测量的需求,提出基于光纤电流传感技术的焊接电流测量方法。建立了光纤电流传感器闭环检测系统动态模型,通过优化系统的前向增益,提升了传感器响应速度和带宽。仿真和实验结果表明:传感器的上升时间约为4.1 μs,在DC~30kHz范围内幅频特性衰减小于0.3%。基于该动态模型计算传感器对焊接电流纹波分量的响应,仿真结果表明:系统的动态跟踪能力可满足对纹波电流的测量需求。利用等安匝法对光纤电流传感器进行校准,在直流5~50kA范围内,传感器的测量误差优于±0.05%。现场实验结果证明了光纤电流传感器用于直流逆变焊接电流测量及电焊电流测试仪现场校准的可行性。     

光纤参数测试方法的研究

本文概括论述了光纤的测试参数及测试方法及不确定度分析。总结了光纤几何参数、模场直径、截止波长、衰减及波长色散的测试方法和不确定度评定方法。归纳出了光纤参数测试中存在的问题和解决方法。     

多功能光纤智能复合材料研究

提出采用光纤微弯传感器测量复合材料固化中粘度的变化。选择了合适的光纤并进行了增敏处理。完成了不同铺层方式的复合材料固化进程的粘度测量, 并与动态介电方法的测量结果进行了比较。结果发现, 光纤微弯衰减方法对于热压情况下复合材料的固化监测是敏感的。该方法可重复性好, 可以准确给出树脂粘度最低点和固化完成点的时间, 灵敏度与光纤同增强纤维的交角有关。利用完成固化监测功能后仍具有光波导性能的已埋入光纤, 研制了两种类型的振动传感器。     

光纤参数测试方法的研究

本文概括论述了光纤的测试参数及测试方法及不确定度分析.总结了光纤几何参数、模场直径、截止波长、衰减及波长色散的测试方法和不确定度评定方法.归纳出了光纤参数测试中存在的问题和解决方法.     

光纤传感器监测复合材料固化过程

设计了两种新型光纤传感器,一种是通过测量光纤末端近场模斑谱反映光纤埋置 脂折射率的变化,另一种行微弯衰减方法测量复合材料固化中铺层被压缩的进程。利用这两种传感器进行了复合材料固化监测实验,结果表明,发现光纤模斑传感器的信号可以反映树脂基体的粘度的变化历程,光纤微弯传感器的信号可以反映铺层被压缩的过程,监测这两个关键的参数变量不但有利于操作工艺的优化,而且为建立复合材料因化过程的智能化在线监控系统奠     

单根光纤光栅监测复合材料固化工艺过程多目标参量技术的研究

采用单根布拉格光纤光栅传感器实现了对复合材料工艺过程不同阶段、不同目标的监测。在成型阶段监测树脂的温度(粘度)发展历程；在施加成型压力时监测树脂内部压力的变化；在固化与降温阶段监测复合材料层板内部的应力变化。试验结果表明，利用-根布拉格光纤光栅传感器同时实现对复合材料固化工艺全过程的主要控制参量的监测是完全可行的。     

多模光时域反射计衰减刻度的检定

本文针对多模光时域反射计的衰减刻度的检测与检定，介绍了标准光纤光，外接光源法和光纤末端反射法三种实验方法。     

关于局域网、城域网光纤测试

随着局域网络的发展，光纤在局域网的地位逐步提高，同时对于光纤测试的要求也在提高。本文从基础维护测试和认证测试两个方面解释了局域网光纤测试的主要概念和参数特点，其中包括通断测试、长度衰减测试，OTDR精度测试、以及常规维护测试等。同时，文章也简单介绍了各种光纤测试在光纤网络布线、施工、验收、维护、抢修中的应用。     

光纤布线系统的测试

1光纤布线系统的一类测试 在现场进行的光纤链路验收测试大家都习惯使用“衰减值”或者“损耗”来判断被测链路的安装质量,多数情况下这是非常有效的方法。在ISO11801、TIA568B和GB50312等常用标准中都倾向于使用这种被称作“一类测试”的方法,特点是：测试参数包含“损耗和长度”两个指标,并对测试结果进行“通过／失败”的判断。     

反射式光纤测振仪的研究

提出了一种反射式光纤测振系统。为克服环境、温度、光源输出、光路损耗等变化引起的漂移，它采用与反射面距离不等的两根接受光纤为参考通道，并利用两根接受光纤输出的信号比构成自补偿网络。本文给出该网络的理论依据，并介绍如何在电路设计上采用相应措施来提高稳定性和保证测试精度     

Fiber optic differential interferometer

Based on low-coherence interferometry in standard single-mode fibers, a differential interferometer has been proposed. A twin-reflective mirror demodulator was used in the differential interferometer. This interferometer can be used as a fiber optic sensor to measure the elongation of the fiber or strain substressed on the fiber and has the advantage that it can automatically compensate for temperature-induced variations in the refractive index and thermal expansion of the silica fibers     

Attenuation Scale Calibration of an Optical Time Domain Reflectometer Using an External Laser Source

Optical time domain reflectometers (OTDRs) are widely used to measure the attenuation of optical fibers. Accurate measurement of the attenuation requires periodic calibration of OTDRs. In this paper, a system is proposed based on the external source method (ESM) to calibrate of the attenuation scale of an OTDR over a dynamic range of around 15 dB. The ESM method has several advantages over the widely-used standard reference fiber (SRF) since it is fast, can be automated and offers direct traceability to the SI units. In order to estimate the accuracy of the proposed setup, an OTDR has been calibrated using the SRF and the ESM methods. The calibration uncertainty of the ESM method is found to be 0.040 dB, which is similar to that of the SRF method which is found to be 0.038 dB.     

驻波比法吸声尖劈测试分析

根据驻波理论,利用PLC、步进电机等设备研制出应用于吸声尖劈声学性能测试的驻波管全自动测试系统,为高效、准确、方便地测量材料吸声性能参数提供了很好的方法和途径;从驻波比选取、是否考虑声波衰减、尖劈的安装方式、传声器的安装位置等几方面,应用此测试系统对底部截面为0.6m×0.6m的吸声尖劈进行测试分析,提出在实际测量当中可以不用考虑声波衰减以及尖劈与传声器的安装问题,而驻波比选取第一组值即可满足工程应用测量需求。     

Effect of uniaxial deformation on the optical scattering losses of a semicrystalline fluorocopolymer

Both small- and wide-angle light scattering as well as transmission measurements have been used to investigate the optical scattering losses of a vinylidene difluoride-tetrafluoroethylene-hexafluoropropylene copolymer crystallized from the melt. The main origin of the scattering loss is the wide-angle light scattering from the spherulitic superstructure. Uniaxial deformation transforms this structure into a fiber morphology. The attenuation of fibers has been measured for light propagating both parallel and perpendicular to the orientation axis. For both directions, the attenuation decreases with increasing draw ratio. Annealing of the fibers while keeping their ends fixed is an effective method to reduce the attenuation further, to a low value as close to that of the melt.     

Attenuation measurement of infrared optical fibers by use of a hollow-taper-based coupling method

An alternative method for attenuation measurement of infrared (IR) fibers is described. The method includes a simple technique for direct laser-to-fiber coupling with an uncoated glass hollow taper. The operating principle of the hollow taper is based on the grazing-incidence effect of light reflection. The hollow taper forms a smooth Gaussian-shaped profile of the output laser emission and provides the proper conditions for equilibrium-mode distribution of optical power within the test IR fibers. The experimental hollow-taper-based coupling method is used for measurement of attenuation and bending losses of various kinds of IR fiber, including solid-core (fluoride, chalcogenide, and germanium-doped) and hollow fibers.     

Wavelength-dependent measurements of optical-fiber transit time, material dispersion, and attenuation

A new, to our knowledge, method for measuring the wavelength dependence of the transit time, material dispersion, and attenuation of an optical fiber is described. We inject light from a 4-ns rise-time pulsed broadband flash lamp into fibers of various lengths and record the transmitted signals with a time-resolved spectrograph. Segments of data spanning a range of approximately 3000 A are recorded from a single flash-lamp pulse. Comparison of data acquired with short and long fibers enables the determination of the transit time and the material dispersion as functions of wavelength dependence for the entire recorded spectrum simultaneously. The wavelength-dependent attenuation is also determined from the signal intensities. The method is demonstrated with experiments using a step-index 200-mum-diameter SiO(2) fiber. The results agree with the transit time determined from the bulk glass refractive index to within ?0.035% for the visible (4000-7200-A) spectrum and 0.12% for the UV (2650-4000-A) spectrum and with the attenuation specified by the fiber manufacturer to within ?10%.     

海底沉积物样品声衰减与温度关系的实验研究

不同海区海水温度不同,导致不同海区沉积物温度不同;实验室环境温度变化造成沉积物温度的变化。模拟沉积物的温度变化来研究沉积物声衰减的变化,分别从声衰减系数和本文提出的温变衰减系数描述声衰减。以原状样品和人工样品为例说明了在一定厚度的海底沉积物中,声波的传播能力受到沉积物本身分布的均匀度的影响,会出现不同的衰减趋势;通过定义温变衰减系数得到了海底沉积物对能量的传播能力随温度的升高而降低。     

非金属复合材料超声波衰减系数测定研究

通过对超声波场场和对影响非金属复合材料衰减系数因素的研究。结合超声信号数字化技术，实现了非金属复合材料衰减系数的测定。所采用的方法简单，易于实现，测定较为准确。     

中型材远程计量无人值守系统

文章简要介绍了利用称重、监控设备对济钢中轧厂第二条矫直生产线钢材计量过程进行监控和录像，并对被监视目标的计量数据、动态图像传输到数百米外原中轧钢材秤操作室内，通过对监控图像监视和控制，在同一主机完成新、旧两台秤的钢材称重操作及数据的自动汇总打印，实现了中型材远程计量无人值守且双秤合一，在提高精度、增加产量、降低成本方面取得良好效果。