Ring sensor and heart rate monitoring system for sensor network applications

A ring-type pulse oximeter sensor attached to the finger and its 24-hour ambulatory heart rate monitoring system are presented. The PCB has been designed with a light-to-frequency converter and the CPU with a built-in Zigbee stack for simple and low power consumption. Also designed is the algorithm using a least square estimator to calibrate various signal distortions caused by motion artefacts for a proper accuracy.     

基于光纤光栅的沥青路面状态的实时监测

为了给沥青路面结构响应监测找到科学有效的测 试手段,本文进行了沥青路面响应光纤Bragg光栅(FBG)实时监测 的研究。应用单轴压缩试验对采用的FBG传感器进行标定,得到了标定方程。基于提 出的沥青路面 FBG传感器埋设方法,在沥青路面成功埋设了FBG传感器。将静载监测结果与BISAR 3.0程序 计算结果进 行了比较。对不同轴重、不同汽车行驶速度及不同温度条件下的沥青路面结构动力响应进行 了实时监测。结果 表明,提出的沥青路面FBG传感器埋设方案可使传感器的成活率达到87%;静载实测结果与 计算结果较为接近,FBG监测结果有效且能准确反映沥青路面各工况下的应变时程;当车速 降低8km/h时,路面应变响应降低达100με以上;而路面温度增 长8℃,路面的竖向变形增长了近200με。     

A rapid-response, high-sensitivity nanophase humidity sensor for respiratory monitoring

An ionic-type humidity sensor based on a plasma-deposited nanophase Si thin film was developed. Detection of relative humidity cycles between 20% and 90% was possible in /spl les/0.2 s with /spl sim/5 orders of magnitude variation in conductance. Such superior performance is attributable to the unique arrayed column-void network structure and ultrafine thickness (e.g., 50 nm) of the Si film as well as to the lateral electrode configuration. Our sensor can be miniaturized, integrated with signal processing circuits, and fabricated on plastics. A crucial implementation, where our sensor would be very suitable and beneficial, is respiratory monitoring.     

Concentration sensor based on a tilted fiber Bragg grating for anions monitoring

The ubiquity and importance of anions in many crucial roles accounts for the current high interest in the design and preparation of effective sensors for these species. Therefore, a tilted fiber Bragg grating sensor was fabricated to investigate individual detection of different anion concentrations in ethyl acetate, namely acetate, fluoride and chloride. The influence of the refractive index on the transmission spectrum of a tilted fiber Bragg grating was determined by developing a new demodulation method. This is based on the calculation of the standard deviation between the cladding modes of the transmission spectrum and its smoothing function. The standard deviation method was used to monitor concentrations of different anions. The sensor resolution obtained for the anion acetate, fluoride and chloride is 79 × 10⁻⁵ mol/dm³, 119 × 10⁻⁵ mol/dm³ and 78 × 10⁻⁵ mol/dm³, respectively, within the concentration range of (39–396) × 10⁻⁵ mol/dm³.     

面向楼宇结构健康的光纤传感网络监测系统研究

楼宇健康监测中对主体结构的整体应力场分布及其状态参数分析是在线状态评估技术的瓶颈性问题。为了全面地、连贯地反映建筑物的整体状态信息,搭建了一种面向建筑物主体结构的光纤传感网络,提出了一种将结构中应力场信息与整体位置偏移数据相对应的映射算法。算法根据材料力学和挠度理论将弯度矩阵用于应力场与位移场的换算。仿真分析了主结构体中水平梁与垂直梁在受到外部载荷时,其应力场的分布规律,从而为传感单元的铺设提供了量化依据。实验采用方形钢与工形钢模拟主结构,加载外部应力范围为200~1000 N,传感单元选用光纤光栅应变传感器,并采用同类型温度传感器进行温漂补偿。测试结果显示,水平梁与垂直梁的交叉位置处最敏感,波长偏移总量约25 nm,梯度距离0.5 m处波长偏移总量为16 nm,波长偏移量可以很好地反映应力场分布。根据波长偏移数据解算的主体结构位置偏移量平均误差7.46%和6.34%。方形钢和工型钢对应的应力与位置偏移量的平均比率分别为1.99×10?7 m和2.79×10?7 m。可见,该系统可以测试计算结构体的整体健康状态。     

一种用于大尺寸结构健康监测的光纤传感器

为了对较大尺寸的复合材料结构进行健康监测,研制了一种干涉型光纤传感器并验证了其性能.传感器由E2000连接器、单窗口光纤分路器、两根端面镀反射膜的单模裸光纤组成.验证结果表明,传感器测量臂的增量与应变增量有线性关系,温度变化对传感器测量臂的长度也有影响,传感器可以用于判断复合材料的损伤,与SMARTEC公司生产的传感器相比,两者测量值相差很小.     

基于光纤光栅传感的变压器绕组温度检测系统

传统温度传感器受到周围环境因素的影响很大,系统采用抗干扰能力强并且对温度极其灵敏的光纤光栅传感器.利用光信号的测量和传输,再解调成温度信号.分析了光纤光栅传感器的原理和系统构成,介绍了软件和硬件的实现.最后的实验结果证明了系统具有较高的测量精度,可满足变压器绕组高精度温度测量要求.     

光纤光栅传感器在航空航天复合材料/结构健康监测中的应用

本文简要概述了光纤光栅传感器的特点及航空航天复合材料的类型,详细介绍了光栅在航空航天复合材料/结构健康监测中的应用和发展状况;指出目前存在的问题,并探讨了相应的对策;展望了基于该类传感器的健康监测技术在航空航天领域的应用前景。     

实时监测光固化过程的光纤传感系统研究

研究了基于光固化材料在固化过程中折射率的不断变化,结合光纤折射率传感原理和光固化特点,采用待测光固化材料固化成型制成光纤传感器,并垂直于光同化方向埋入被测材料中,通过监测光固化材料同化过程中特定位置处折射率的变化来获取其固化程度和最佳曝光时间等信息.实验结果表明,实验数据与理论分析一致;所采用的特殊光纤传感器,能实现传感器与被测材料折射率的匹配,保证监测的灵敏度和数据的可靠性.     

Performance enhancement of BOTDR fiber optic sensor for oil and gas pipeline monitoring

Distributed fiber optic sensor which based on Brillouin scattering has become increasingly popular due to its unprecedented advantage of simultaneously measuring temperature and strain. The Stimulated Brillouin Scattering (SBS) threshold, sensing distance, signal-to-noise ratio and spatial resolution are critical parameters to the performance of Brillouin Optical Time Domain Reflectometry (BOTDR) sensor. This technical paper presents the result of simulations as well as theoretical discussions on suppressing unfavorable fiber optic nonlinearity, SBS by using a statistical approach which is design of experiment (DOE). Due to the fact that there are a number of SBS threshold factors, there is a high possibility that multiple strong interactions exist among these factors. Conventional methods of plugging each factor one-at-a-time are not efficient as interactions between factors are totally ignored. The result had shown SBS suppression by 11 dB to achieve the maximum sensing distance of up to 110 km. Besides, a 3-bit simplex coding is employed when launching the laser pulses to enhance the SNR at the receiver. Simulation results demonstrated a 1.38 gain in SNR and a higher SBS threshold.     

New endless polarization control method using three fiber squeezers

In a polarization control system using two fiber squeezers of limited range, the reset causes momentary signal loss. To prevent this loss, an extra squeezer is required and a special controlling algorithm must be developed. A theoretical approach to the problem is presented resulting in such an algorithm. The presence of angular misalignment between the fiber squeezers is also discussed     

Design and characteristic analysis of fiber optic Fabry-Perot sensor for static ice strain monitoring

Sea ice is one of the important natural disasters.A new method based on optical fiber Fabry-Perot sensor for ice strain measurement was proposed to meet the needs of ice strain monitoring.A high sensitivity optical fiber Fabry-Perot pressure sensor with thin-film structure was realized by means of pressure assisted arc discharge method,and the sensor was encapsulated by metal tube /PDMS /AB epoxy glue combination method.On this basis,the static internal strain characteristics of ice in the process of melting and freezing during -15℃～0℃ was studied.Experimental results show that this proposed thin-film fiber Fabry-Perot pressure sensor has good sensitivity characteristic in ice strain monitoring,it is believed of great value for the monitoring of remote distributed sea samples.     

基于光纤光栅传感器的飞行器结构健康监测

综述了光纤光栅传感器在飞行器结构健康监测中的研究现状,概述了光纤光栅传感器的工作原理和特点,研究了基于光纤光栅传感器的飞行器结构健康监测系统的组成和主要研究内容。     

健康监测系统中光纤传感器网络优化布置研究

针对健康监测系统中不合理的传感器布置将影响传感器数据采集的有效性,降低监测系统的精度,以基于光纤Bragg光栅(FBG)传感器网络的结构健康监测系统为研究对象,采用逐步积累法,对系统中传感器网络的优化排布方法进行了研究。首先采用Ansys力学仿真软件建立了试验件的有限元模型并进行了加载试验,然后采用仿真获得的数据对传感器排布位置进行了优化,最后按照仿真研究获得的传感器优化位置在试验件上进行了试验研究。结果表明,试验同仿真结果具有很好的一致性,相对于原始传感器网络的排布方案,在相同的系统监测精度下,优化后的传感器排布方案可以采用更少的传感器;如果采用相同数量的传感器,优化后的传感器排布方案可以获得更高的监测精度。     

基于光纤压力传感器的管道监控系统研究

针对运输管道埋设于土壤中面临的泄漏或堵塞点难发现、难定位的问题,结合光纤压力传感器高灵敏度、高抗干扰的特性,设计了一种基于光纤压力传感器的管道监控系统。系统采用包覆有合适热膨胀系数材料的单模光纤组成的偏振型压力传感器,能很好地克服外界环境温度扰动;采用模块化设计的压力敏感探头以20 m间距均布于管线上,形成信号点阵列源;结合点阵列数据重构与插值定位算法确定故障点的位置。结果表明:该系统的光纤压力传感器可有效克服温度变化对传感测量的不良影响,5.5 km范围内对故障点的定位精度在1 m内。     

分布式光纤传感器开关柜温度监测探讨

阐述了分布式光纤温度传感器的工作原理,根据电力设备温度监测的特点,探讨了用于高压开关柜温度在线监测的传感系统方案。设计了基于全分布式和准分布式光纤传感技术的高压开关柜温度监测系统,比较了不同监测系统的特点,指出了适用于电力系统高压开关柜温度测量的方法。     

新型微结构光纤超声波传感监测系统的设计

基于新型微结构光纤,采用光纤环形激光器,设计了一个新型超声波传感监测系统。进行了理论分析和实验验证,取得了超声波导致光纤布喇格光栅的相对光谱偏移数据,从激光强度变化对冷腔损耗调制的响应进行检测。     

基于分布式光纤传感器的光缆监测系统改进方案

针对目前现存光网络监测系统在安全管理功能方面存在的不足,提出了一种应用分布式光纤传感器改进现有光缆监测系统的方案,并提出了此改进方案的基本流程图及其逻辑分层结构,完善了现有光网络监测系统的安全管理功能.     

光纤光栅传感技术在隧道火灾监控中的应用

分析了国内现有的隧道火灾监控系统现状,介绍了光纤光栅传感技术的原理,阐述了这一新技术在工程应用中的优点,并提出了基于光纤光栅感温探测器的隧道火灾报警监测系统,并结合工程实例介绍了该系统在隧道火灾监控中的应用。     

利用双激光光源监测甲烷浓度的光吸收法光纤传感器

基于Lamber -Beer定律 ,利用波长为 1.3 3 μm的脉冲lnP/InGaAsP半导体激光器作为测量光源 ,用低损耗的光纤进行光信号的传输并以钽酸锂热释电探测器作光电转换器件 ,设计出了一种新颍的远距离监测甲烷浓度的光纤传感系统。以此光纤传感系统为探头 ,设计出了一种可实时监测甲烷浓度的仪器 ,并能实现 3km的远距离遥测。介绍了该光纤传感系统及由该光纤传感系统构成的监测仪器的基本结构与工作原理 ,讨论了其中的技术难点及其相应的解决方法 ,并给出了监测仪器相应的技术指标