基于超声导波的水下管道缺陷检测

文中介绍一套可拆式传感器系统设计与制作,利用超声导波原理对水下管道的腐蚀进行检测,基于厚度剪切模式的压电陶瓷和可拆式固定装置组成,可拆式传感器系统包括传感器PZT特别设计,并且可以把传感器装置夹在要检测的管道上。当对水下设备的管道进行了一系列的测试,结果表明传感器系统能够有效地激发和接收T（0,1）模式的超声导波,由于T（0,1）模式超声导波能够在水下管道上长距离传播,因此适用于缺陷检测。人为缺口的回波信号与缺口的尺寸以及位置具有良好的相关性。研究表明这一可拆式传感器系统能够利用导波有效地对水下管道进行检测。     

油气管道高速漏磁检测系统中传感器研究和设计

为了提高漏磁检测的精度,文章研制了一种用于油气管道漏磁检测系统中的电磁感应式传感器,该传感器安置在二维高速漏磁检测装置中,实现对油气管道缺陷信号的实时检测,获得管道的缺陷信号.介绍了传感器的结构,带磁汇聚装置的磁化系统装置;设计实验与普通的霍尔传感器的检测精度进行分析比较.试验结果表明该传感器在高速管道漏磁检测中能够检测到微小缺陷,比霍尔传感器有更高的灵敏度.     

基于二进制编码的管道缺陷超声检测方法研究

脉冲信号激励的超声波用于管道缺陷检测时,存在平均发射声功率小及探测信号频带单一的局限,且在多发多收的阵列检测场合,很难确定接收回波的发射源,不利于被测体全声场的声学特征参数解算。为此,提出了采用正弦波频率调制的二进制超声编码方法检测管道缺陷。建立传感器编码激励响应的数学模型,通过仿真得到了传感器在不同激励频率、分数带宽和码位数下的幅频响应规律,并实现了对接收信号的有效区分和发射声源的有效标识。将该方法用于管道缺陷的超声检测,实现了管道不同种类缺陷的有效检出和发射声源的有效标识,并分析了二进制编码激励方式下缺陷对不同频带的敏感性。统计结果表明,2~4位码对管道渗漏孔和裂纹缺陷的检出率高于62%,对回波信号的标识正确率高于97%。     

测量矩阵对管道超声压缩采样系统性能的影响

基于压缩传感(Compressed Sensing,CS)理论的管道超声压缩采样系统可用于解决长距离能源输送管道在役超声检测数据量大的问题,然而该系统的性能受到多种因素的影响,测量矩阵的多样性是最重要的影响因素之一。针对此问题,采用不同于约束等距性(Restricted Isometric Property,RIP)的统计方法分析了测量矩阵对系统性能的影响机理,提出了优质原子比和相对渡越时间误差作为衡量测量矩阵性能优劣的指标。管道超声检测实验结果表明,该项技术可作为压缩采样中测量矩阵的选择依据,为管道中进行超声检测信号压缩采样提供借鉴。     

新一代环形共振式光纤陀螺问世

新一代环形共振式光纤陀螺问世阎永志就测定移动体姿态或旋转用速度而言，以前采用机械陀螺与距离传感器和速度传感器相组合的方式进行。近年来，随着陀螺品种的增加，扩大了其使用范围，例如，振动陀螺被用于ＶＴＲ摄像机防抖；气体陀螺与ＧＳＰ相组合用于汽车导航；特别...     

基于位置传感器的微细管道内表面无损检测

基于位置传感器(PSD)的特性,提出了一种长距离曲线型微细管道内表面形貌无损检测技术,开发了相应的管道内表面形貌检测器。激光束经过2次反射后,在管道内壁上形成细小的光斑。该光斑被二维PSD接收,产生4路电流信号。根据这些信号和检测器的结构参数,可以计算出对应光斑在局部三维坐标中的位置。反射镜在微型马达带动下旋转1周,使激光束完成1个管道截面环的扫描,从而得到该截面上所有采样点的相对坐标。最后对测量数据进行分割、拟合等处理,重构出截面环的形状,得到该截面处的管道半径以及缺陷情况。在微型管道机器人的带动下,可以对整条管道进行检测和三维重构。根据该技术开发的检测系统,可以实现内径在9.5~10.5 mm、曲率半径大于100 mm的曲线型长距离微细管道内表面的检测,对管道内壁缺陷的测量精度达到±0.1 mm。     

微反射镜阵列角位置检测中的光斑串扰抑制算法

针对微反射镜阵列（MMA）微反射镜集中度高、尺寸小，在实际检测过程中相邻镜面反射光容易出现串扰的问题，提出了一种用于微反射镜阵列角位置检测的光斑串扰抑制算法。对照射到阵列中待测微反射镜及邻域微反射镜上的光强进行标定，通过求解光强矩阵方程获得每个微反射镜的角位置信息。仿真结果显示，在检测光斑尺寸大于单个微反射镜尺寸的串扰情况下，该方法的检测精度可保持10μrad以上，满足光刻机使用指标需求。所提出的检测方法可有效解决MMA检测过程中的串扰问题，对光刻机自由光瞳照明模块的角位置检测具有重要意义。     

可用于小口径光束波前检测的横向剪切干涉仪

提出了一种可用于小口径光束波面检测的横向剪切干涉仪。该干涉仪由偏振分光棱镜、光轴与其表面平行的晶体平板、1/4波片、反射镜及CCD构成。被测光束由偏振分光棱镜进行透射起偏和反射检偏,利用反射镜的反射两次经过晶体平板、1/4波片来实现剪切光束的等光程干涉。通过晶体平板剪切复制波面以获得小的剪切量,可用于小口径光束波面的检测。晶体平板的旋转可以改变剪切量,实现了不同口径不同波前的光束波面检测。对该干涉仪进行了仿真分析,得到了不同入射角情况下的剪切干涉图,仿真结果与理论分析结果相一致。实验中,旋转晶体平板得到的剪切干涉图与仿真结果相一致,很好地验证了该剪切干涉仪的有效性。     

制造二极管激光反射镜的新技术

据麻省理工学院林肯实验室的研究人员说，一种质量传输技术可能改善化学刻蚀二极管激光小面反射镜的质量，甚至可以制得倾斜的反射镜。这种技术已经用于高产额制造掩埋式异质结激光器，并在二极管激光器的基片上制作反射镜，它可以使光束指向上方。     

小孔径炮膛视觉检测系统的光学设计

设计了一套管道内窥系统,能对小口径炮膛进行快速、准确的视觉检测.该系统采用偏心结构,并将第一片物镜设计为柱面镜,以适应物距小、被检测管壁面为非平面的特殊性质;利用平面反射镜将光轴方向由径向转为轴向,以方便后续物镜和图像传感器的安排.光学系统的外形尺寸为φ18 mm×33 mm(径向×轴向),视场覆盖范围大于四分之一圆周,可对直径小至35mm的炮膛进行清晰成像检测;在空间分辨率为50 lp/mm时,MTF值均高于0.6,镜头畸变量小于0.1%,保证了检测精度.针对炮膛检测的客观条件,对该镜头的结构特点进行了分析,并给出了设计结果.     

基于物联网技术的油气管道安全监测可视化管理系统

针对长距离油气管道安全监测与管理范围大、距离远而不易实时监测、准确定位等问题,提出了基于传感器、通信、计算机等物联网技术设计的油气管道安全监测系统方案,有效利用现代技术对长距离油气传输管线进行监测管理.简述了系统架构、主要组成和基本原理.系统中的安全监测传感器模块由压力传感器与短程通信模块综合集成;辅助与应急监测包括车载查验系统和微型无人机查验系统,形成管道故障立体监测体系;系统管道泄漏远距离定位采用光纤应变分布法既提高了定位精度又兼顾了通信.该方案部分已在多个工程领域成功应用,满足现场监测管理要求,系统应用前景广阔.     

Decision support system for inspection and maintenance: a case study of oil pipelines

The existing method of pipeline health monitoring, which requires an entire pipeline to be inspected periodically, is unproductive. A risk-based decision support system (DSS) that reduces the amount of time spent on inspection has been presented. The risk-based DSS uses the analytic hierarchy process (AHP), a multiple attribute decision-making technique, to identify the factors that influence failure on specific segments and analyzes their effects by determining probability of occurrence of these risk factors. The severity of failure is determined through consequence analysis. From this, the effect of a failure caused by each risk factor can be established in terms of cost and the cumulative effect of failure is determined through probability analysis. The model optimizes the cost of pipeline operations by reducing subjectivity in selecting a specific inspection method, identifying and prioritizing the right pipeline segment for inspection and maintenance, deriving budget allocation, providing guidance to deploy the right mix labor for inspection and maintenance, planning emergency preparation, and deriving logical insurance plan. The proposed methodology also helps derive inspection and maintenance policy for the entire pipeline system, suggest design, operational philosophy, and construction methodology for new pipelines.     

Transmission of planar, cylindrical and spherical multiple dielectric layer systems

The transmission of planar, cylindrical and spherical waves has been studied for single dielectric layer, resonant tunnelling and multiple period Bragg reflector systems. Interesting features originating from the geometry are found in the cylindrical and spherical systems and their applications are discussed.<>     

Dielectric sensor for detecting capsules moving through pipelines

Recent advancement in the technology of hydraulic capsule pipeline (HCP) for transporting freight in capsules has made it imperative to use a practical sensor to detect capsule movement in pipelines. The detection of capsules is especially needed in the pump bypass of HCPs for the control of valves that must be opened and closed periodically and frequently without touching and damaging the capsules. A new sensing technique is described for the detection of capsules and coal logs moving in pipelines. An equivalent electric circuit of the sensor is proposed and verified experimentally. Test data show the effectiveness and reliability of this sensor. This new sensor may also have application to detecting “pigs” used in ordinary liquid and gas pipelines, and detecting the interface of multiphase or multiproduct flow in pipelines     

Autonomous system for oil pipelines inspection

Maintenance of oil pipelines is an issue of great concern for oil companies. Any possibility of leakage must be detected before the leakage occurs and a preventive action should be taken in order to avoid losses of oil and ecological disasters. One of the main causes of oil pipelines leakage is the corrosion of the bottom part of the pipeline due to accumulation of water and other corrosive substances.One of the methods used to check the conditions of the oil pipelines is the running of a data acquisition device through all the length of the pipeline (that can be km) to gather information about the corrosion and its position inside the pipeline. This device is commonly referred to as pig. The Brazilian oil company, PETROBRAS, wanting to have the technology of such device to detect corrosion in their oil pipelines proposed to the Department of Mechanical Engineering of the Escola Politécnica da Universidade de São Paulo a joint project to the development of a pig that could run uninterruptedly in long oil pipelines gathering corrosion data for the preventive maintenance of their oil pipelines. The result of the project was the development of an ultrasonic pig with 16 ultrasonic transducers with on-board energy system and acquisition and storage systems. Also, comprised in the presented solution was the development of a software to analyze the collected data and give the position of the corrosion spots along the pipeline. This paper presents in detail the implementation and design issues related to the development of the ultrasonic pig. Also, some experimental data will be shown as confirmation of the effectiveness of the developed system.     

管道超声内检测发射电路设计

在深入分析超声检测发射电路的基础上,设计了基于RLC串联谐振的发射电路,电路以场效应管为开关元件,电感储能形成高频、高压脉冲,建立了发射电路理论模型,分析了电路参数对高压窄脉冲的影响,理论计算产生的宽频高压脉冲激励信号与实验测量结果一致。该电路不需要提供直流高电压,只需要5V单电源供电,就可稳定获得宽度小于1μs,幅度大于400V,且无余振的高压窄脉冲。电路具有结构简单、体积小、不需要直流高压、功耗低、易于集成等特点,满足管道超声内检测的要求。     

管道附件影响的管道声发射信号衰减特性

以包含多种附件的液体和气体管道为对象,开展复杂结构管道声发射信号的衰减特性研究。通过采集不同流量压力下管道本体的声发射信号,分析其幅值衰减规律,并用DB8小波包与快速傅里叶变换(FFT)研究管道声发射信号成分变化。通过采集阀门、法兰、流量计等6种管道附件前后的声发射信号并分析衰减规律,发现对声发射信号衰减影响最大的管道部件为电磁流量计。之后重点分析了法兰上螺栓连接紧固程度对信号幅值和频率成分的影响,实验结果表明,螺栓紧固程度越高,声发射信号衰减越小。本文的相关研究结论对工程中进行输油或输气管道进行声发射检测时的传感器布设决策具有集成化的参考价值。     

Design and experimental study on FBG hoop-strain sensor in pipeline monitoring

Pipeline monitoring is an important task for the economic and safe operation of pipelines as well as for loss prevention and environmental protection. The circumferential strain is of significance in pipeline integrity monitoring. In this paper, an indirect pipeline corrosion monitoring method based on the circumferential strain measurement is firstly proposed, with main objectives at designing a circumferential strain measuring device. Combined with unique advantages of optical fiber sensing, an FBG hoop-strain sensor was designed and encapsulated. Its enhanced sensitivity mechanism in the circumferential strain measurement and manufacturing technique is detailed. The experimental study of the developed FBG hoop-strain sensor is conducted on a PVC model pipeline to investigate its characteristics, including reliability and some tentative dynamic tests. Results of model tests show that the FBG hoop-strain sensor demonstrates good performance in the circumferential strain measurement, and can be considered as a practical device for pipeline health monitoring.     

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。