数控装置接口电路的改进

某数控系统由传感器、数控装置和接口等部分组成,由于传感器的输出电流很微弱,接口检测电路受环境干扰的影响,灵敏度不高。同时,数控装置的接口起动电流也不稳定,造成传感器与数控装置不能同步运行。实践证明,采用改进后的接口电路,取得了较好的控制效果。传感器的短路电流I=1 mA,频率在5 Hz左右,传感器的输出电流与其负载电阻的关系如图1所示。为了消除环境干扰,提高传感器的灵敏度,传感器的负数控载装电置阻的取输用入RZ电=阻0·1为75ΩΩ微,起电动阻电。流为100 mA。改进后的接口电路如图2,集成运放的电源电压为±12 V,设传感器两端a…     

管道腐蚀检测中新型脉冲涡流传感器的设计

提出了一种新型脉冲涡流传感器设计思路。它将脉冲涡流激励场从空间上转化为匀强涡流场,从而等效为一种自差分式的涡流检测技术,因此无需进行差分处理,可避免差分信号的不同步导致的检测精度和灵敏度不高。采用该新型脉冲涡流传感器对钢管腐蚀缺陷进行了检测,试验结果表明设计的传感器具有较高的灵敏度和检测精度。     

液压系统油液在线监测电容传感器的优化设计

设计了圆弧型极板油液监测电容传感器的结构,应用电磁场理论对传感器的电容值及检测场的灵敏度进行了计算和分析;应用ANSYS有限元分析软件,对传感器内部的电势分布和场强分布进行了仿真,得到与计算结果相一致的传感器特性,即传感器检测场内部灵敏度分布不均,在靠近极板边缘处灵敏度高,在中心处灵敏度低。应用正交实验法,对此结构传感器的主要参数进行了优化,得到了一组最优的结构参数,同时提出了传感器两对极板相错90°的极板优化排列方案。     

基于双层静电极的差动式电容力矩传感器

力矩传感器在机器人关节实时力矩监测中起着重要作用,为提高电容力矩传感器灵敏度,提出一种双层静电极差动式电容力矩传感器。利用PCB板表面的双层静电极与悬臂梁动电极垂直分布构成的电容器作为力敏元件,将由梯形梁变形引起的电容变化量以差值方式输出,通过推导单层与双层静电极传感器的输出特性,证明双层静电极传感器具有更高灵敏度。对传感器进行受力仿真分析,验证结构设计的合理性,并进行静态标定实验,得出双层静电极传感器灵敏度为单层静电极传感器灵敏度的1.8倍,最大非线性误差约为2.19%,重复性误差约为1.84%。该实验结果表明双层静电极传感器具有更高灵敏度,满足机器人关节测力的需求。     

压力传感器灵敏度特性的研究

针对应变片在圆平薄膜上的两种布置方式，导出圆平薄膜压力传感器灵敏度的计算公式，分析应变片布置方式和位置以及温度对灵敏度的影响，通过理论计算与实际测量结果比较，指出提高压力传感器灵敏度的有效途径为采用轻掺杂的应变电阻。分析应变片2种布置方式压力传感器灵敏度与温度的关系。     

脉冲数字式射线传感器

介绍了一种脉冲数字式射线传感器,由盖革计数管、高压电源、专用模块及编程控制器软件组成。电路采用了模块设计,通过使用专用模块,简化了硬件电路,基本不需要调试。传感器的响应时间、灵敏度能通过可编程控制器分别进行调节。采用脉冲数字式射线传感器的射线管道爬行器具有灵敏度高、稳定性高、误动作少的特点。     

基于Lamb波频散特性的声发射源平面定位新方法

针对传统的声发射源平面定位中各传感器灵敏度差异和门槛值设置不同对时差定位精度影响较大的问题，通过研究弹性波在薄板中传播的特性即Lamb板波频散特性，借用模态声发射的概念将单个传感器接收到的信号利用Gabor小波时频分析得到不同模态的峰值到达时间，并在引入速度因子概念的基础上，讨论了两种不同的声发射源平面定位方法，即同一频率不同模态的定位方法和同一模态不同频率的定位方法，试验证明两种方法都能得到模拟源的正确定位，不仅从根本上避免了传感器间灵敏度差异对时差定位精度的影响，而且还可以减少平面定位中传感器的数量，避免三角形定位中伪定位的出现，并适用于传统的声发射源平面定位中不易布置传感器阵列的结构健康无损监测。     

石墨烯柔性压阻传感器微织构压缩应变机制

为满足智能机器人、电子皮肤等领域对柔性传感器高灵敏度日益增加的需求,通过设计高表面积形貌以制备石墨烯凸台微织构柔性传感器,并对比分析有无微织构传感器的灵敏度;基于结构力学方程与静电方程,建立微织构柔性传感器模型,开展了电场作用不同基底厚度以及微织构间距下柔性传感器微织构应变的数值模拟,研究柔性压阻传感器微织构压缩应变机制,探寻机械载荷和电载荷的交互作用关系。结果表明,柔性基底的微织构化处理能有效提高柔性压阻传感器的灵敏度。模型总位移的最大值随基底厚度的增加呈非线性增加,微织构应变随着厚度的增加而减小。电场作用下微织构应变受机电耦合压力叠加的影响均大于无电场作用。框状微织构类似于悬臂梁,作用在微织构上的力矩随间距增加而增大,同时刚度减小,微织构的压缩形变增加,应变增大。组合尺寸微织构的应变随着微织构间距的增加而增大,制备多尺寸微结构传感器可使用（150+350）μm的组合尺寸,能够有效增加接触面积提高传感器灵敏度。机械载荷和电载荷的耦合作用,组合尺寸对力矩与刚度的分配有效增加了基底的应变,提高了柔性传感器的灵敏度。     

压气机叶片根部原位检测传感器的设计与制作

在外场航空维修中,发动机叶片根部原位探伤时存在涡流检测传感器适用性不强、灵敏度低、可达性差的难题。基于涡流环理论,结合压气机叶片根部的形状特点,对传感器的磁芯检测面进行加工制作,设计与叶片根部吻合度高的仿形涡流检测传感器,实现对叶片根部疲劳裂纹缺陷的原位检测。试验结果表明:新设计的仿形传感器能够消除因为叶片根部形状不规则带来的提离影响,且传感器稳定性好、灵敏度高。     

巨磁阻传感器在涡流检测中的应用

巨磁阻传感器是一种新型的磁性传感器,与传统的磁性传感器相比,有着灵敏度高、可靠性高和线性好等优点。介绍巨磁阻传感器的原理及其在涡流检测中的应用,实例表明采用巨磁阻传感器的涡流检测系统可以得到很好的检测结果。     

Ultrasonic arrays for non-destructive evaluation: A review

An ultrasonic array is a single transducer that contains a number of individually connected elements. Recent years have seen a dramatic increase in the use of ultrasonic arrays for non-destructive evaluation. Arrays offer great potential to increase inspection quality and reduce inspection time. Their main advantages are their increased flexibility over traditional single element transducer methods, meaning that one array can be used to perform a number of different inspections, and their ability to produce immediate images of the test structure. These advantages have led to the rapid uptake of arrays by the engineering industry. These industrial applications are underpinned by a wide range of published research which describes new piezoelectric materials, array geometries, modelling methods and inspection modalities. The aim of this paper is to bring together the most relevant published work on arrays for non-destructive evaluation applications, comment on the state-of the art and discuss future directions. There is also a significant body of published literature referring to use of arrays in the medical and sonar fields and the most relevant papers from these related areas are also reviewed. However, although there is much common ground, the use of arrays in non-destructive evaluation offers some distinctly different challenges to these other disciplines.     

Structural health monitoring of anisotropic plates using ultrasonic guided wave STMR array patches

Structural health monitoring (SHM) of plate-like structures used in aerospace industries, using transducer arrays located suitably on the structure, such as the single-transmitter multiple-receiver (STMR) array [Wilcox PD, Lowe M, Cawley P. Lamb and SH wave transducer arrays for the inspection of large areas of thick plates. Review of progress in quantitative nondestructive evaluation, vol. 19A. Melville, NY, USA: American Institute of Physics; 1999. p. 1049–56; Wilcox PD. Guided wave beam steering from omni-directional transducer arrays. Review of progress in quantitative nondestructive evaluation, vol. 22A. Melville, New York, USA: American Institute of Physics; 2002. p. 761–8], has been demonstrated here. The reconstruction of the material state was carried out by utilizing a phased addition reconstruction algorithm. In addition to the signals from damage sites, the ultrasonic guided wave-based reconstruction procedures also need the complete set of elastic moduli as a continuous input throughout the SHM process. In the present study, two flexible printed circuit board (PCB)-based patches: ((i). single-quadrant, double-ring STMR material characterization (MC) array and (ii). Full-ring STMR SHM array) were developed for accomplishing both objectives, i.e. (a) online MC and (b) SHM of anisotropic plate-like structures, respectively. Experiments were conducted on 3.15 mm graphite-epoxy composite plate using PCB-based STMR arrays, the feasibility of accomplishing both objectives was demonstrated.     

A small 2D ultrasonic array for NDT applications

A prototype of two-dimensional transducer array with reduced number of elements, based on segmented annular distribution is presented. The capability of this array to produce volumetric imaging is compared to the equivalent conventional 2D squared matrix array. The comparison between both apertures is made for the cases of the full-array emission/reception mode and SAFT mode. From the analysis it is deduced that the segmented annular arrays produce lower grating lobes than squared arrays, improving the image contrast. The fabrication process of a segmented annular array of 64 elements and the experimental work made with this array transducer is also presented in this paper.     

乳化液浓度在线检测与控制的试验研究

论述了乳化液浓度在线检测与控制技术的意义并进行了试验研究。试验证明了应用超声波传感器对乳化液浓度进行在线检测的可行性,并得出了相应的模型与参数。此方案适宜在冷轧、机械行业应用。     

Analysis of ultrasonic C-scan image features and image processing for spot welding

A focused ultrasonic transducer is used for precise, step-by-step, surface ultrasonic scanning inspection of spot welds. Two methods for generating characteristic data matrices of ultrasonic echo signals of the spot welds are established. One is based on the ultrasonic echo amplitude and the other is based on frequency spectrum. Both methods generate scanning inspection data arrays and provide clear C-scan images. Based on C-scan noise reduction, the Krisch edge detection operator for edge detection-a gray window transform-reflects the shapes of the spot welds and allows quantitative determination of their size. The method based on the ultrasonic echo amplitude provides a greater quantitative detection accuracy.     

Frequency dependent directivity of periodic permanent magnet electromagnetic acoustic transducers

Beam steering has been achieved using shear horizontal waves generated using a periodic permanent magnet (PPM) electromagnetic transducer (EMAT). Unlike phased arrays, where steering is achieved by carefully controlling the firing of individual elements, the spatial periodicity of the PPM EMAT is ultilised to steer the beam whilst exciting all elements simultaneously. Due to the periodic nature of the array, the interference of individual waves from each of the elements creates a highly frequency dependent angle of propagation, allowing the directivity to be changed by simply varying the frequency of the input signal. Simultaneous excitation precludes the need for complicated and expensive phased array hardware. A frequency domain model is developed so that the beam characteristics, such as steering angle and beam width, can be calculated, allowing for investigation into the beam steering qualities of the PPM transducer. Broadband pulsed generation is also demonstrated, showing how a wave is generated over a large range of angles, meaning a large area can be covered with a single pulse. Interesting properties of this wave, such as a variation of frequency as a function of angle, and how this can be useful, are also discussed.     

西藏措勤盆地油气遥感解译

西藏措勤盆地油气勘探潜力大,利用遥感解译方法可以解决研究区高寒缺氧、交通不便以及常规油气勘探方法成本高等问题。利用比值法、遥感波段融合法、羟基/铁质异常提取法对措勤盆地异常信息进行提取和分析,并与油气苗点和已知油气藏对比。结果表明,羟基/铁质异常提取法(主要分析手段是主成分法)包含的非油气异常信息少,异常信息与油气苗点吻合度高,是最佳的解译方法。比值法提取的异常信息中包含较多的非油气异常信息,因此油气解译结果不准确。遥感波段融合法解释准确性介于两者之间。通过遥感解译预测出措勤盆地4个有利油气勘探区域,其中3个与该区石油地质分析结果非常吻合。     

Laser-drilled PVC template for electrodeposition of multi-core orthogonal fluxgate sensing element

The sensing performance of the multi-core orthogonal fluxgate sensor has been found to be significantly enhanced as compared to single-core orthogonal fluxgate sensor, with the magnitude of the enhancement proportional to the number of core wires in sensing element. One of the methods of making the multi-core sensing element could be a template deposition approach, in which laser drilling of hole arrays in PVC templates and then electrodeposition of the soft magnetic pillars in the holes are involved. As such, the optimization of the Nd:YAG laser parameters on the quality of the holes on the PVC templates has been carried out in this study. The effect of laser processing parameters, including: (1) laser fluence; (2) laser irradiation time; (3) number of pulses; (4) laser focal point, was investigated in relation to the hole quality and tapering effect. In particular, the laser fluence was the major factor in determining hole diameter and depth. The laser irradiation time affects the heat affected zone the most severely, and the number of pulses used ensures a hole that is relatively clear of debris. In order to obtain holes of the best quality finish, high laser fluence and optimum values of laser irradiation time and number of pulses should be used. By setting the focal point above the surface of the PVC, the tapering effect was found to be minimum.     

基于VC++的无线传感器振动信号采集与处理系统开发

针对目前众多的基于无线传感技术的信号采集系统中缺少专门用于振动信号的采集与处理软件以及基于有线传感器的振动信号监测系统存在的问题,以Visual C++为开发平台,采用面向对象的思想,基于无线传感器网络技术开发了无线传感器振动信号采集与处理系统。该系统集成了振动信号的采集和常用的振动信号处理功能,使得研究人员能够更加方便地进行实验数据的采集以及实时处理。系统开发完成后,在反共振试验台上对该系统进行了测试。测试结果表明:该系统操作简单直观,可以方便地进行信号采集与处理、无线节点参数设置及状态监测等操作。     

钛合金阳极氧化法制备自组装纳米多孔结构薄膜

钛及钛合金在含有F-离子的电解液中阳极氧化,可自组装制备出有序TiO2纳米多孔或纳米管阵列薄膜,这类纳米阵列膜材料具有极大的内比表面积和优异的电子传输性能,可以用作纳米结构制备模板、高灵敏度传感器、染料敏化太阳能电池等。以TLM钛合金为阳极氧化的基片,通过改变阳极氧化电压、钛合金相结构,找到了制备纳米多孔阵列的参数,通过条件试验发现,在恒电压小于30V时,经时效处理的TLM钛合金表面可以制备得到合金元素掺杂的TiO2纳米多孔结构薄膜。