基于SOA脉冲调制的BOTDR应变检测系统

电光调制器调制光脉冲时易受偏振态与偏压影响,造成调制脉冲平均功率与消光比不稳定,影响检测系统稳定性,实际中需通过复杂算法校正。本文提出半导体光放大器调制光脉冲的方法,通过改变注入泵浦电流调制光脉冲,采用相干探测结合微波频率扫描方法,获取不同频率点下自发布里渊散射信号,经洛伦兹拟合得到布里渊散射谱,实现光纤沿线布里渊频移解调,并搭建了基于半导体光放大器的BOTDR分布式应变检测系统。实验中选取2.943km光纤末端施加500με,频移测量误差在±0.5MHz范围内。研究表明可实现稳定应变检测。     

基于分布式光纤传感器的地下原水管道(廊)沉降监测研究

地下管廊、原水管道沿途地质情况复杂,地基承载力低、承载后变形量大,易发生不均匀沉降事件,致使敷设在其上的供水管道遭受破坏。为减轻巡查工作,节约沉降测量成本,研究基于分布式光纤传感的管道监测系统,将传感光纤铺设在管片上,对管廊进行实时监测。基于应变-沉降机理模型,对监测系统进行了实验验证,根据实验数据得到应变-沉降曲线的平均绝对误差约为1.23mm。研究结果表明,该系统对于管道（廊）不均匀沉降事件具有监测距离长、响应及时和误报率低等特点。     

布里渊散射分布式光纤传感技术的研究进展

阐述了基于布里渊散射的分布式光纤传感技术测量光纤温度/应变的基本传感原理。介绍了基于光时域反射仪发展起来的几种传感技术,布里渊光时域反射(BOTDR)、布里渊光时域分析(BOTDA)、布里渊光频域分析(BOFDA)分布式光纤传感技术,特别对BOTDR的原理和典型系统方案进行了详细的介绍。最后,叙述了基于布里渊散射的分布式光纤传感技术当前的进展和趋势。     

小波阈值降噪提高ＢＯＴＤＲ测量精度研究

布里渊光时域反射仪（Brillouin Optical Time Domain Reflectometer, BOTDR）通过单端探测 光纤中的自发布里渊散射来实现布里渊频移测量,存在信噪比较低的缺陷。为此,本文采用小波阈 值降噪对微波外差扫频 BOTDR 测量过程中的每条单频功率曲线进行噪声抑制,最终提高 BOTDR 测量精度。简述了小波阈值降噪原理,构建了基于微波外差扫频测量的 BOTDR 仿真模型,通过仿 真分析不同小波变换参数对测量精度的影响,确定了最佳小波阈值降噪方案。搭建了微波外差扫频 BOTDR 光路及电路实验装置进行温度测量实验,在 10km 传感光纤上对降噪算法进行了实验验证。 实验结果表明,相比于降噪前,降噪后传感光纤末端变温区布里渊频移测量波动极差从 5.8 MHz 降 低至 3.2 MHz,均方根误差由 1.2 MHz 降低至 0.16 MHz,测温精度由±2.545℃提升至±1.4℃。理论仿真和实验研究证明,采用小波阈值 降噪可提升 BOTDR 测量精度。     

蓄电池组充放电温度与应变光纤光栅监测系统研究

针对蓄电池组充放电过程中个别电池异常发热、外壳鼓包、变形、胀裂等潜在的火灾隐患问题,本文根据光纤光栅的温度敏感和应变敏感特性设计了基于光纤光栅传感的循环扫描式蓄电池组充放电温度与应变监测系统,并提出一种融合改进小波去噪、滑动平均及高斯拟合算法的优化寻峰算法来提高系统的测量精度。经实验验证,该方法可以将温度测量精度控制在±0.12℃以内,应变测量精度控制在±1.37με以内,综上,本文提出的方案适用于蓄电池充放电过程中的温度与应变监测。     

输电铁塔塔身光纤光栅结构监测与时序融合研究

输电铁塔多处复杂地质结构,受不同地质灾害、风作用等影响易发生压坏、倒塔等现象,严重威胁电力系统稳定运行。常规目视巡视方法经济损耗大,不能及时发现问题。选取具有三层横担形式的双回路直线型输电塔,通过对输电塔ANSYS仿真分析获得应力分布。采用一种基于光纤Bragg光栅（FBG）传感网的输电铁塔在线监测系统测得塔身应变数据。通过分批估计与基于标准差的加权平均时序融合分析处理方法分别对4只FBG应变传感器在近半年采集的样本数据进行了融合,得到4支FBG应变传感器的时序融合值为：61.67με、61.37με、61.97με、61.82με。融合后的值可用于提高损伤识别的准确率,常规的目视巡视方法得到改善。     

机敏水泥基材料及其无线应力/应变测量系统的研制

为监测混凝土结构性态,开发了一种机敏镍粉水泥基材料及其无线应力/应变测试系统.首先,给出了填充镍粉的水泥基材料的应力/应变传感单元的制备方法、测量原理和性能分析;其次,制作了应力/应变的无线测试系统;最后,完成了机敏镍粉水泥基材料的无线应力/应变测试系统的实验.结果表明,机敏镍粉水泥基材料的电阻率随着压应力/应变是线性可逆变化的;集成的无线压应力/应变测试系统的测量范围在0 Mpa/0με到2.5 Mpa/311.5με,无线应力/应变系统可以实现应力/应变灵敏度为16.894%Mpa-1/0.133 65με-1(即应变灵敏度系数为1 336.5)和分辨率为150 Pa/O.02με;新开发的机敏镍粉水泥基材料的无线应力/应变测试系统具有应力/应变灵敏度高、分辨率高、电路简单等优势,适合结构健康监测用.     

分布式光纤测温技术在煤矿中的应用

介绍了分布式光纤测温原理,重点分析了分布式光纤测温系统在煤矿带式输送机、输电电缆、电气设备和采空区火灾防治中的应用及具体的实施。工业性试验表明,该分布式光纤测温系统能准确、快速地对温度进行监测和预警,测温误差为±1℃,定位精度为1m,响应时间为20s。     

基于短栅区光纤光栅传感器的油气管线腐蚀在线监测系统研究

基于短栅区光纤光栅传感器设计了一种油气管线腐蚀在线监测系统。对应油气管线外表面周向非线性应变,该系统可以测量油气管线腐蚀缺陷,保障管线安全运行。通过对管线圆柱型腐蚀缺陷周向应变特性及光纤光栅应变传感模型的理论分析,设计了3mm短栅区光纤光栅的应变传感阵列,并在模拟油气管道上验证了测量圆柱型缺陷表面周向非线性应变的可行性。结合波分复用、时分复用技术及光纤光栅解调系统可以组成解调7×7个应变及1个温度补偿共计50个光纤光栅传感器的在线监测系统。该系统已应用于中海油渤南龙口天然气终端处理厂,监测结果表明该在线监测系统稳定可靠,是监测油气管线腐蚀状况,保障管线安全运行的一种有效可靠方法。     

光纤管道安全预警系统的研究与应用

介绍了一种基于Mach-Zehnder光纤干涉仪原理的分布式光纤管道安全预警系统。该系统利用与油气管道同沟敷设的普通通信光缆中的3根光纤作为分布式传感器,长距离连续监测油气管道沿线的土壤振动情况,并分析判断可能威胁油气管道安全的破坏事件,及时报警,起到安全预警的作用,能够对这些事件进行精确的分析和定位,详细阐述了系统的原理和组成。经过理论分析和测试结果表明,该系统具有较高的灵敏度和定位精度。     

Simultaneous strain and temperature measurements in composites using extrinsic Fabry–Perot interferometric and intrinsic rare-earth doped fiber sensors

This paper reports on a novel optical fiber-based sensing system for conducting simultaneous strain and temperature measurements. The sensor design involves the use for the first time of an extrinsic Fabry–Perot interferometric (EFPI) strain sensor in conjunction with a rare-earth doped fiber fluorescence decay-time based temperature sensor. The combined sensors were embedded in a carbon fiber reinforced composite system and evaluated. The feasibility of using this type of embedded sensor configuration for simultaneous strain and temperature measurements was demonstrated.     

微型应变传感器的设计与制造

把压敏电阻敏感元件、温度补偿电路和高电平放大器,在硅片上采用集成技术制成微型应变传感器,它有电压及频率两种形式的输出。给出了该传感器的设计、制造和测试结果。这种传感器也可以做压力传感器使用,不过在设计几何布局和制造处理上略有不同。     

Spatial-frequency multiplexed fiber-optic Fizeau strain sensor system with optical amplification

A novel method for multiplexing fiber-optic Fizeau strain sensors with optical amplification is proposed and demonstrated. This method overcomes the two intrinsic disadvantages of fiber-optic Fabry–Perot (F–P) strain sensors, i.e. weak signal and difficult multiplexing. The amplified spontaneous emission (ASE) and optical amplification are used simultaneously to enhance the interferometric signal considerably. A Fizeau interferometer formed by two fiber ends with a quite different reflectivity is used to replace the F–P cavity in sensor head design. Such a Fizeau cavity can enlarge the cavity length by at least an order of magnitude and allows more than 10 sensors to be multiplexed simultaneously by using spatial-frequency multiplexing. The operating principle of the sensor system is discussed and an experiment is carried out to verify the concept of the method proposed. It is anticipated that such a sensor system could find important applications for health monitoring of large structures.     

Effect of strenuous live-fire drills on cardiovascular and psychological responses of recruit firefighters

The study examined the effects of repeated strenuous live-fire drills on cardiovascular and psychological responses of male recruit firefighters (n = 7). Participants performed three trials of a standardized set of tasks while inside a training structure containing several live fires. Measurements of heart rate, aortic blood flow, perceived exertion, respiratory and thermal distress, reaction time, and error rate were obtained before testing, after each trial and during recovery. Heart rate increased significantly during each of the trials, reaching age-predicted maximal values. Stroke volume was significantly lower after trial 3 versus trial 1 and prevalues. Perceived exertion, respiratory distress, and thermal distress all increased, indicating greater stress following firefighting activities. Reaction time and error rate did not change significantly, but there was a tendency for more errors following trials 2 and 3 versus trial 1. The training drills resulted in considerable physiological and psychological strain, which has the potential to impair cognitive function. Firefighters are encouraged to take all possible steps to mitigate the extent of the cardiovascular strain.     

CSE620R分切机退卷控制器参数调校的新方法

文章针对CSE620R分切机退卷张力控制系统过去使用过渡膜调校方法的不足,从理论上对各个需要调校的参数进行理论计算和曲线校对,并将计算结果对控制板进行设定和曲线校对.这既提高了调校精度又达到稳定生产的目的.避免了浪费大量的薄膜和能耗.     

Selected physiological and psychological responses to live-fire drills in different configurations of firefighting gear

The purpose of this study was to examine selected physiological and psychological responses to strenuous live-fire drills in different configurations of protective firefighting gear. Career firefighters (n = 10) performed three sets of firefighting drills in a training structure that contained live fires in two different configurations of firefighting gear. On separate days subjects wore: (a) the NFPA 1500 (1987) standard configuration, and (b) a hip-boot configuration of the firefighting gear. Physiological and psychological measurements were recorded pre-activity and at the end of each trial. Repeated measures ANOVA revealed a strong trend for performance time to be greater in the 1500 gear than in the hipboot gear. There was a significant Time × Gear interaction for tympanic membrane temperature, with temperature being greater in the 1500 gear. Perceptions of effort and thermal sensations were also greater in the 1500 gear than in the hip-boot configuration of the gear. There was little difference in mean performance on cognitive function measures between the two gear configurations, but there was greater variability in performance in the 1500 gear. These data suggest that performing strenuous firefighting drills in the current NFPA 1500 standard configuration results in longer performance time, greater thermal strain, and greater perception of effort and thermal sensation.     

Physiological strain during kitchen work in relation to maximal and task-specific peak values

Six female and three male subjects from a hospital kitchen volunteered for the study. The subjects were working on a conveyor belt collecting and sorting dirty plates, glasses and cutlery for cleaning. In the study, a medical examination, a maximal clinical exercise test with a 12-lead electrocardiogram (ECG) and a maximal arm cranking test were performed in the laboratory. Further, each subject was studied for 30 min during a normal work shift in the kitchen. Oxygen uptake (VO₂) and heart rate (HR) were continuously registered. During the work period, a rating of perceived exertion (RPE) was asked at the 5th, 15th and 30th minute. Physiological responses were measured by a portable system (K4) both in the laboratory and in the field. VO₂ and HR measured in the field were proportioned to corresponding maximal values during cycling and to peak values during arm-cranking. The mean VO₂ for the male and the female subjects during kitchen work was 0.65±0.16 l min^-1. This corresponded to 24% of VO_2max and to 41% of VO_2peak during arm-cranking. The difference was significant (p<0.001). Owing to a magnetic field at the conveyor belt, reliable HR values were obtained only from the female subjects. The mean HR during work among the female subjects was 101 beats min^-1. It corresponded to 55% of HRmax and 67% of HR during arm-cranking (p<0.05). The present study shows that the peak relative work intensity is markedly higher when it is expressed relative to the corresponding muscle group's VO_2peak instead of the VO_2max. Similar difference was also seen in the HR response. More task-specific testing of physical capacity may provide improved evaluation of physical strain in a job.     

混凝土应变计转换系数的测试方法研究

建筑工程检测领域常用混凝土应变计检测混凝土的结构应力应变,混凝土应变计的转换系数是影响检测结果准确度的重要参量.本文通过对振弦式应变计和电阻应变片式应变计的结构和检测原理进行分析,分别给出了对应的应变计转换系数测试方法,并列举了部分用到的标准器具     

光学神经网络的现状与进展

通过介绍两种典型的光学神经网络ＯＮＮ－透镜阵列互连网络和全息互 网张,讨论了不前ＯＮＮ的现状,存在问题及发展趋势。还介绍了图样间联想和洗牌网等ＯＮＮ模型中的新算法和新拓扑结构。