磁致伸缩位移传感器检测信号分析

实验研究了磁致伸缩位移传感器的探测电压信号,以便提高磁致伸缩位移传感器的检测精度。分析和验证了波导丝材料、驱动脉冲电流、检测线圈等参数对磁致伸缩位移传感器输出电压的影响规律。对检测线圈进行了优化设计,基于实验数据确定了传感器的各项参数值。实验发现磁致伸缩系数大、魏德曼效应显著的Fe-Ga材料作为波导丝,可明显提高电-磁-机械能的转换效率,获得较大的检测电压信号。研制了新型Fe-Ga波导丝磁致伸缩位移传感器样机,并与Fe-Ni波导丝传感器进行了性能对比。结果表明,与Fe-Ni波导丝相比,Fe-Ga波导丝磁致伸缩位移传感器的检测信号明显增强,信噪比显著提高,其检测电压信号幅值比Fe-Ni波导丝检测电压信号幅值提高了40mV,相应的传感器精度提高了2倍。     

基于SH波的埋地管道泄漏监测方法

埋地管道在服役过程中受到工作载荷波动、周围环境变化等复杂因素的影响,易发生泄漏等事故,建立一种泄漏定量在线监测技术是提升埋地管道运行安全性的有效手段。为此探索了黏性媒质对矩形横截面杆中SH波传播的影响规律,研究了SH波衰减与粘滞系数和波导杆结构的相互影响规律。研究发现粘滞系数和波导杆表面积分别与SH波衰减呈现单调对应关系,推导了波导杆中的SH波衰减粘滞阻尼方程,设计了一种基于SH波衰减的埋地管道泄漏在线监测湿度传感器,建立了基于SH波的埋地管道泄漏监测方法。搭建试验台,开展SH波湿度传感器监测埋地管道泄漏可行性试验。试验发现,当湿度传感器选定并且埋入深度固定时,SH波衰减公式可以定量地表征土壤的湿度,根据SH波衰减公式测量土壤湿度相对误差不大于8%,即基于湿度传感器建立的埋地管道泄漏监测方法能定量地判断管道泄漏情况。     

水凝胶波导探针的制备及对罗丹明B的超高灵敏检测

波导型倏逝波传感器依赖于待测物与倏逝场的相互作用,其检测能力受制于倏逝波的强弱。一般而言,波导的倏逝波强度在内部传输光中占比很低,因此传感器灵敏度受到很大限制。提出的一种基于水凝胶聚合物的波导探针可以克服上述缺点。水凝胶具有的三维网状结构,可以方便待测物渗入波导内部,因此可以利用局域在波导内部的传输光进行探测,大幅提高探测光的利用效率。此外,实验通过其他聚合物单体的添加成功抑制了水凝胶波导遇水溶胀变形带来的额外光损。由于纯水凝胶制备的波导在吸水溶胀后会导致变形,从而带来额外的光损耗,因此除水凝胶之外还需掺入其他聚合物以维持波导的基本形状。实验表明,该水凝胶聚合物波导传感器对罗丹明B水溶液的吸收检测极限为1.0×10^?9 g/mL,荧光检测极限为1.0×10^?19 g/mL。相比于其他波导型倏逝波传感器,荧光检测极限提高了约7个数量级。该水凝胶聚合物波导传感器制备方法简单,成本低廉,可适应性高,灵敏度高,在医疗及环境监测等多个领域都有着广泛的应用前景。     

基于水凝胶聚合物波导传感器检测盐酸吖啶黄

多功能化是光纤化学传感器的重要发展方向。为实现该目标,首先通过激光诱导波导自形成技术制备了一种光纤–水凝胶聚合物波导–光纤传感结构,并在水凝胶聚合物波导探针中成功地掺杂了纳米金颗粒。在该结构中,波导与光纤同轴无缝相连,保证了探测光和信号光的高效利用。掺金后的聚合物波导具有丰富的光谱探测能力,利用该波导探针成功实现了对盐酸吖啶黄的吸收、荧光以及拉曼光谱的检测,扩大了波导传感器的应用范围。     

飞机杆力传感器检测仪研制

针对某型飞机杆力传感器测试的实际需要,提出了相应的杆力传感器检测仪的设计方案,分析了其基本测试原理和过程,加工制造了该型检测仪并进行了实际测试。结果表明,该型飞机杆力传感器检测仪操作简单,功能完善,智能化程度高,检测快速准确,为飞机杆力传感器性能检测提供了科学的手段,具有较好的推广前景。     

微纳流体光波导及其在生物传感器中的应用

微纳流体光波导融合了微观流体与微光学特征,能够在相同物理空间实现流体介质和微光学信息功能及结构的集成,是生物化学分析及生物传感器的关键器件.本文综述了微纳流体光波导研究现状及其在生物传感器和生物化学分析中的应用实例.论述了实现微纳流体光波导的全反射机理、多层干涉效应,抗谐振反射机理,以及基于上述机理实现的各种流体波导形式.重点分析了基于微纳流体层流效应的全流体波导,基于多层干涉效应的Bragg光波导、空心光子晶体波导、狭缝光流体波导、抗谐振反射光波导等多种波导的特点.指出狭缝光流体波导和抗谐振反射光波导具有更好的设计灵活性,且检测灵敏度高、可靠性好、易于集成制造,可望在生物传感器及微纳流体光学系统中得到更广泛的应用.     

涂覆高折射率树脂薄膜的聚合物波导传感器的制备

倏逝波的强弱决定了波导型倏逝波传感器的探测极限。在波导表面涂覆一层高折射率树脂薄膜,提高光波导外倏逝波的占比。高折射率薄膜的涂覆可以大幅度改变波导中的光场分布,并提高倏逝波强度。通过研究不同折射率下倏逝波占比与镀膜厚度间的相互关系,得到了不同折射率下的覆膜最佳厚度。通过激光诱导波导自成型技术在聚合物波导上涂覆了一层折射率为1.6,厚度为300 nm的树脂薄膜。光谱测量结果表明,经过薄膜涂覆后,传感器对罗丹明B水溶液的吸收检测极限提高至1×10^-9 g/mL,比未覆膜传感器高了10倍。该传感器成本低、体积小、制作简单、灵敏度高,在各个领域都拥有广阔的应用前景。     

适合于液相检测的乐甫波传感器

乐甫波（Ｌove wave)是声表面波的一种，它是在沉淀于压电基片表面的薄层声波导中传播的表面剪切横波。论述了基片为ＳＴ切压电石英晶体、声波导层分别为聚甲基丙烯酸甲酯（PMMA）和熔融石英（SiO2)的乐甫波器件的制作。通过测量器件的传输参数S21和插损，比较了瑞利波器件和不同声波导层构成的乐甫波器件在气相和液相的特性，证明了乐甫波传感器适合于液相检测而瑞利波传感器不适合，而且，SiO2是构成乐甫波器件声波导层的更合适的材料。     

实用传感器电路（三）

六、光纤传感器的光输出/脉冲变换电路 用反射型光纤传感器检测物体通过和存在的方法,能进行不接触检测物体,传感器还便于跟检测对象接近,现已广泛应用。反射型光纤传感器和光波导器件一样,将发射光的光纤芯线和检测对象的反射光聚合起来,并通过光纤芯线送到检测端,在发射光中,一旦有待检测物横向穿过,将其反射光聚集起来并输出。因此,传感器的输出通常是一个待检测物通     

高折射率镀膜聚合物波导传感器的制备

为了提高利用倏逝波传感的光纤传感器的灵敏度问题,仿真并验证了一种基于高折射率镀膜的光纤传感器.首先两根光纤之间利用激光诱导波导自行成技术形成聚合物波导,并在波导表面镀上一层高折射率Ta2O5薄膜以增强波导表面倏逝波强度,从而增加传感器灵敏度.根据聚合物波导制备结果,使用COMSOL Multiphysics?软件对Ta...     

The effect of regular differences in a cross section on the testability of a rod tested by the acoustic waveguide method

The mechanism of acoustic noise generation in a rod with regular differences in the cross section is studied theoretically and experimentally. The effects of the rod’s geometry and the basic control parameters on the testability of the rod tested by the acoustic waveguide method are evaluated. Recommendations for improvement of the rod’s testability are made.     

An analysis of the comparative reliability of acoustic testing methods of bar stock from spring steels

The results of comparative tests of the electromagnetic-acoustic mirror through transmission method of multiple reflections and alternative (visual, acoustic waveguide, and eddy current) methods during rod testing under factory conditions at various plants are given and their comparative reliability is calculated.     

Waveguide attachment influences on acoustic emission evaluation for marginal disintegration of dental composite restorations

Influence of the waveguide attenuation was investigated on acoustic emission (AE) estimation for the marginal disintegration states of dental composite restorations. For the AE measurement, a human molar tooth substrate with an artificial class 1 cavity was made. A bonding agent was applied and a composite resin was tightly packed in the hole of the substrate. Under the light exposure to the composite resin the polymerization shrinkage occurred and the marginal failure generated AE waves. It was ascertained that the waveguide attachment brought about a great decrease in AE hits and amplitudes. Compensation for the attenuation loss of the AE parameters could offer some equivalency to the AE measurements by the direct attachment of the sensor on the substrate.     

管式夹套容器内管泄漏声发射监测试验研究

为了监测管式夹套容器在加压过程中的内管泄漏情况,及时发现泄漏源。在实验室内建立管式夹套容器内管泄漏声发射检测系统,通过研究泄漏声发射信号的波形、幅值和不同频带能量分布规律,以及利用波导杆检测管式夹套容器的方法,为现场检测提供试验依据。     

Discussion of the Definition for Acoustic Emission Event in the Time Series of Concrete Damage Process

Acoustic emission signals from concrete compression damage process are non-stationary and their arrival time is unknown. Therefore, the definition on the acoustic emission event in the time series is not clear. In this paper, the acoustic emission signals associated with concrete specimen under uniaxial compression are acquired by full-digital acoustic emission system. The overlapping phenomenon of acoustic emission signal is presented and discussed by the analysis of time interval between adjacent hits. Acoustic emission signals are classified into three categories according to their waveform characteristics. And the result shows that as the loading process continues, more and more amount of continuous type of acoustic emission signals appeared, indicating the acoustic emission signal does not carry the features of burst type, which will introduce obvious errors in the calculation of acoustic emission event. In contrast, the average signal level used in the analysis of continuous type of acoustic emission signal shows a good regularity with the damage process of concrete.

     

Acoustic spectrometry as used for the evaluation of tribological systems

A study is presented of tribological metal-polymer systems. Parameter analysis by acoustic emission resulting from external friction was used. The experimental results obtained for metal-polymer friction pairs are dependent on various factors including load, velocity of relative travel, microgeometry of the contacting surfaces, physicomechanical properties of the materials and testing period. The rates of acoustic emission, the total acoustic emission and the magnitude of the frequency emission spectrum were used as informative characteristics concerning friction and wear kinetics. A number of general relations were determined for friction pairs, reflecting the influence of these factors on the acoustic activity of a rubbing contact. A relation was discovered between the mode of wear for polymers and the acoustic emission parameters. An assumption was made concerning the correlation between polymer mass loss by wear and the energy of acoustic emission as based on the model under consideration for failure of a simple contact spot.     

Universal Waveguide for the Acoustic-Emission Evaluation of High-Temperature Industrial Objects

An original waveguide design has been proposed that makes it possible to carry out acousticemission inspection, diagnostics, and monitoring of industrial objects operating at temperatures above 85°С. The waveguide ensures higher heat-dissipation characteristics, with minimum acoustic losses, than the known clamped-type waveguides. Its application involves no changes to the test object and requires no special permissions from supervising authorities. The underlying physical operating principles, specific features of embodiment, application possibilities, and results of the full cycle of research into how waveguide design features influence heat-dissipation and acoustic characteristics are described. The use of such waveguides widens the application field for the acoustic-emission method as an express technique for evaluating the technical condition of high-temperature objects both during operation and before decommissioning them for technical diagnostics with the aim to identify active (hazardous) areas and include them into the program of testing with other nondestructive methods.     

Acoustic emission during orthogonal metal cutting

The theory of acoustic emission and the analysis of emission signals is reviewed as it applies to generation of acoustic emission in metal cutting. Based upon the mechanics of the orthogonal cutting operation a relationship is developed between the root mean square (RMS) voltage of the acoustic emission and fundamental cutting parameters. The validity of this relationship is evaluated by a series of tests varying cutting speed, feed and rake angle for orthogonal machining. Strong dependence of the RMS voltage of the emission on both strain rate and cutting velocity was observed. The sources of acoustic emission in metal cutting are discussed and areas of additional work in the study of acoustic emission from metal cutting are identified.     

基于声发射和神经网络的风机叶片裂纹识别研究

提出一种对风力机叶片裂纹声发射信号进行模式识别的方法。该方法以叶片无裂纹、萌生裂纹、扩展裂纹和断裂四个阶段为声发射源的四个模式,基于声发射信号含有丰富的发射源信息的特点,通过大量采样获得叶片裂纹声发射信号参数,并依照叶片裂纹声发射参数分析的数值特点确定BP神经网络,用选定的网络对叶片裂纹阶段进行模式识别,以判断裂纹的危害程度。仿真结果表明,利用BP神经网络可以对声发射信号进行有效识别,识别准确率达到90%以上。     

声发射技术在磨削加工监测中的应用

近十几年来,声发射技术在机械加工方面获得了普遍的关注,其理论与方法已成为现代制造系统用来监测加工过程状态的一个重要的研究领域。文中概述了声发射（AE)技术的基本原理,讨论了磨削过程中声发射源产生机理,介绍了声发射技术在磨削加工监测方面的研究进展,简要指出了研究中存在的主要问题和发展方向。