小径管超声检测应注意的几个问题

由于小径管环向对接接头本身结构的特殊性决定了小径管超声检测一直是超声检测的一个难点,本文对小径管对接焊缝超声检测中探头选择、探头性能参数测试、时基线调整、根部缺陷波识别等应注意的几个问题进行了介绍。     

T型焊缝内部缺陷超声波检测方法的探讨

T型焊缝作为一种常见的焊接结构,被广泛地应用于工程实践中。T型焊缝的质量直接关系到工程的整体质量,因而焊缝内部缺陷的检测显的尤为重要。文中介绍了直探头和斜探头联合检测的超声波检测方法,并对不同K值的斜探头检测结果进行分析比较,以便于在实际工作中选择合适的探头,更有效地检出内部缺陷,保证工件的质量和安全。     

薄板钢件超声双晶探头的设计

在薄板超声波检测中,由于缺陷往往存在近场区内,因此缺陷不易检出,为了提高检测精度,满足3mm～6mm薄板焊缝超声波探伤的需要,结合检测中遇到的实际问题,笔者研制了双晶横波斜探头,此探头具有灵敏度高,杂波少、盲区小,工件中近场区长度小等优点。     

基于电磁超声技术的管道壁厚检测研究

将电磁超声技术应用于管道壁厚检测现场时,由于探头换能效率低而导致底面反射信号弱、测量结果精度低、数据稳定性差等问题出现。本研究采用试验验证的方法对电磁超声探头中,检测线圈的缠绕圈数和永磁铁的磁场强度进行了优化,并在外径100mm和300mm的碳钢管道上进行了壁厚检测试验。结果表明：随着检测线圈圈数和磁场强度的增大,底面反射信号的波形更加清晰、幅度更高,整个声程范围内的噪声干扰明显降低。优化后的电磁超声检测系统能够满足管道壁厚检测的技术要求。     

超声波地下高压储气井壁厚腐蚀测量及探伤系统

<正>由山东省特检院鲁特科技开发公司与上海鼎声联合幵发的地下储气井井壁自动化综合检测系统为专门用于野外地下储气井定检应用的综合测量系统,可定量检测出壁厚腐蚀及管壁内的周向裂纹。该设备经过多年的实践检验,工作稳定,操作方便,数据分析准确。原理与特点:1、该设备采用阵列式探头,将壁厚腐蚀检测和裂纹检测综合在一起,使储气井检测更加全面。2、检测器整合了探头激励、信号接收放大、信号处理与传输功能,提高了信号保     

高分辨焊缝漏磁检测数值模拟研究

基于漏磁检测原理,利用有限元对管道焊缝漏磁进行计算分析,分别研究探头提离和缺陷深度对漏磁场及其分布情况的影响。计算结果表明,探头提离对漏磁场信号值有很强的影响作用,随着探头提离的增大,漏磁场先快速减小后变化缓慢;改变焊缝上缺陷的深度,漏磁场强度会随着深度增加而增大。通过分析数值信号和探头提离的非线性关系,以及缺陷的漏磁信号在对称位置上的对称关系,可借此设计交错阵列排布的一种焊缝漏磁检测的高分辨探头。     

承压设备NOE新通道(续)——ASME对超声TOFD技术的应用规定 第二部分:焊缝TOFD定量检测方法

<正>5定量误差分析TOFD检测中使用的超声波探伤仪、探头的选定,探头的配置,以及计测数据等,均会引起缺陷测深误差。5.1缺陷偏位误差由缺陷偏离两探头间距中分平面的横向位置引起的TOFD测深误差如图8所示,可由下式求得:     

论灵敏度对锻件超声检测有效性的影响

本文通过分析单晶直探头超声检测锻件时调整灵敏度的方法,论证了不同的调整方法对检测实施的有效性是不同的,提出了保证检测的有效性应该采用的灵敏度调整方法。     

小管径薄壁管对接焊缝超声检测“K”值选择的要求

薄壁管对接焊缝的超声检测,其方法和工艺,现已较为成熟,且被广泛应用。但在日常接触中,却发现有人在检测时,其在探头的选择和应用上较为随意,尤其是对管壁为5mm的工件和对其他薄壁管检测时,竟全用k=2.0的探头,这会引起对埋藏在焊缝中的缺陷产生误判和漏检,并对特种设备的安全运行造成了事故隐患。这里以超声原理结合检测实际,进行分析和探讨,供同行们参考。     

管子和管道环向对接焊缝超声波检测技术探讨

钢制管子和管道的焊接质量关系到特种设备的安全运行,对其焊接质量的内部检验主要依赖于无损检测技术。本文分析了管子和管道超声波检测的困难,分析了解决这些困难的方法,提出了在检测中探伤仪器、探头、试块及校准等方面的要求,指出了现有GS试块的缺陷,并给出解决方案。     

改进灵敏度矩阵的矿井通风故障源诊断及传感器布置研究

利用当前的矿井通风安全监测监控系统,只能反映安设风速传感器的井巷风量发生变化,至于变化是由该条巷道故障引起的,还是由于拓扑关系原因引起的,都无法诊断故障源,通风系统的故障可以归结为分支的风阻发生变化。如果分析每一条分支风阻变化对通风系统的影响,即每一条分支都安设风速传感器是不可能的。因此,井下风速传感器的布置最小数量及位置问题也是研究的重点。改进灵敏度矩阵,建立分支灵敏度0-1矩阵和通风网络故障巷道范围库,用以确定可能引起风速超限的故障巷道范围。最后,提出最少全覆盖布点法,给出分支覆盖度和影响巷道范围库的概念,用以求得风速传感器的宏观布点。     

Impact analysis of multi-sensor layout on the source term estimation of hazardous gas leakage

In chemical industry, sensors are used to monitor the leakage and emission of hazardous materials that are used for hazard warning and risk assessment to ensure safety production. The traditional sensor layout designs the scheme at single-layer, and thus causes large deviations in the estimated height and accuracy of source term estimation (STE). In this study, a dual-layer layout scheme for sensors is proposed. The numerical experiments verify that the improved schemes with an equal number of sensors, as well as detection errors, are beneficial to the accuracy of the STE results. The influence of the heights of the sensors and leak source on the results of STE is studied. Results show that the dual-layer sensor scheme with adjacent intervals at high places in the potential search space is highly favorable to locate the leak, and the scheme arranged near the ground is conducive for improving the estimation accuracy of source intensity. This study also compares the STE results of computational fluid dynamics (CFD) simulated scenarios under different sensor schemes and verifies the effectiveness of the proposed dual-layer sensor deployment scheme with adjacent intervals under turbulence condition.     

A CFD-based approach for gas detectors allocation

Accidental gas releases are detected by allocating sensors in optimal places to prevent escalation of the incident. Gas release effects are typically assessed based on calculating the dispersion from releasing points. In this work, a CFD-based approach is proposed to estimate gas dispersion and then to obtain optimal gas sensors allocation. The Ansys-Fluent commercial package is used to estimate concentrations in the open air by solving the governing equations of continuity, momentum, energy and species convection-diffusion combined with the realizable κ-ε model for turbulence viscosity effects. CFD dynamic simulations are carried out for potential gas leaks, assuming worst-case scenarios with F-stability and 2 m/s wind speed during a 4 min releasing period and considering 8 wind directions. The result is a scenario-based methodology to allocate gas sensors supported on fluid dynamics models. The three x–y–z geographical coordinates for the sensor allocation are included in this analysis. To highlight the methodology, a case study considers releases from a large container surrounded by different types of geometric units including sections with high obstacles, low obstacles, and no obstacles. A non-redundant set of perfect sensors are firstly allocated to cover completely the detection for all simulations releases. The benefits of redundant detection via a MooN voting arranging scheme is also discussed. Numerical results demonstrate the capabilities of CFD simulations for this application and highlight the dispersion effects through obstacles with different sizes.     

基于光纤光栅的斜拉索振动参数监测实验研究

斜拉索是斜拉桥的主要受力构件 ,对其动力特性进行监测具有重要意义。斜拉索工作条件恶劣 ,现有的测试方法难以实现长期在线监测 ,实现斜拉索的振动在线测量 ,传感器是问题的关键。光纤光栅传感器具有极其优良的稳定性 ,已被证实适用于长期监测 ,在结构监测领域具有非常广泛的应用前景。笔者提出了一种基于光纤光栅传感器的斜拉索动力特性在线监测方法 ,建立了用光纤布拉格光栅作传感器监测斜拉索振动的测量模型 ,为验证该模型建立了模拟试验装置 ,在实验室进行了模拟实验研究 ,并将光纤光栅和传统的电阻应变片两种测量方法进行了实验对比。与传统测试手段相比 ,该方法结构简单 ,成本低 ,并能实现斜拉索动力特性的长期在线监测。     

声激励锚杆轴力监测传感器的研制

根据现有的锚杆支护方式,提出一种采用声激励来监测锚杆轴力的新方法,该方法属于无损检测。阐述了锚杆轴力监测传感器的基本原理,介绍了传感器的构造及参数的设置,从强度、模态、声学3个方面进行了详细说明,分析了共振板的厚度变化对声学性能的影响。结果表明,该传感器满足设计要求,方法可行、有效。     

结构响应与损伤识别敏感性探讨

利用小波多分辨分析的特性,研究结构不同位置加速度响应信号对损伤的敏感性问题。通过对一个5层框架结构在不同损伤工况下的数值计算结果表明,不同位置的加速度传感器表征结构损伤特性的能力是不同的,每一传感器只能描述其附近区域结构的工作状态。如果仅利用某一个或者某一些传感器信息进行损伤诊断,就有可能导致错误的诊断结论。只有综合利用多传感器的数据信息,才能使损伤识别更具全局性,才可能准确地识别出结构损伤的发生。     

Real-world effects of rear automatic braking and other backing assistance systems

Objective: To evaluate the effects of rearview cameras, rear parking sensors, and rear automatic braking systems on backing crashes. Method: Negative binomial regression was used to compare police-reported backing crash involvements per insured vehicle year in 23 US states during 2012–2015 among General Motors vehicles with Rear Vision Camera alone; Rear Parking Assist alone (rear parking sensors); Rear Vision Camera and Rear Parking Assist; or the Rear Vision Camera, Rear Parking Assist, and Rear Automatic Braking to vehicles with none of these systems. Modeling controlled for other backing assistance systems on vehicles and factors that may affect crash risk. Results: The combination of Rear Vision Camera and Rear Parking Assist reduced backing crash involvement rates by 42%. When Rear Automatic Braking was added to the Rear Vision Camera and Rear Parking Assist, vehicles with all three systems had backing crash involvement rates that were 78% lower than vehicles with none of the systems. On vehicles with Rear Parking Assist alone or Rear Vision Camera alone, backing crash involvement rates were reduced 28% and 5%, respectively, but these reductions were not statistically significant. Conclusions: Rearview cameras and rear parking sensors are preventing some backing crashes, but their effectiveness may be constrained in part by drivers not using or responding to the systems appropriately. Rear automatic braking adds to the effectiveness of these systems because it does not rely entirely on appropriate driver response. Practical applications: Rear parking sensors and rearview cameras are available on most new vehicles, but availability of rear automatic braking is limited. If more vehicles were equipped with rear automatic braking that performed like the system evaluated in the current study, many backing crashes that still occur among vehicles with rearview cameras and rear parking sensors could be prevented.     

基于决策树的矿井通风阻变型故障诊断及传感器优化布置

为实现矿井通风阻变型故障智能诊断,解决风速传感器优化布置与诊断模型不匹配的问题,提出基于决策树的矿井通风故障位置分类判断、故障量回归预测及嵌入式风速传感器优化布置一体化方法;以唐安矿为例对上述方法进行验证.结果表明:矿井通风空间数据集无量纲化能提高故障诊断准确率、提升模型收敛速度,剪枝能提高模型泛化能力;以基尼系数为嵌...     

建立钢丝绳断丝信号数据库的探讨

钢丝绳是提升、运输及牵引设备中的重要构件,钢丝绳断丝直接影响钢丝绳的强度,霍尔元件的漏磁通法可检测钢丝绳断丝根数和位置。整个系统由检测传感器、漏磁传感器、速度传感器、位移传感器等,数据采集、处理、分析系统,工控机等组成。钢丝绳断丝数据库的主要内容有检测信号的峰值、阈值波宽、钢丝绳直径、钢丝直径等7个基本因素。     

基于微型惯性传感器的井下人员跟踪定位系统*

为了解决当前煤矿井下使用的WIFI人员定位系统在煤矿井下复杂环境中受到干扰,造成使用精度误差等问题,研究并提出使用微型惯性传感器制作足部轨迹测量传感器,通过惯性轨迹测量算法计算并跟踪井下人员的移动轨迹。使用基于固定阈值的零速检测技术和基于Kalman滤波的零速校正技术估计并校正由于系统长期工作造成的偏移误差。通过实验证明采用微型惯性传感器能够在不依赖于外部传感器的情况下对人员轨迹实现测量跟踪,Kalman滤波的应用能够减少惯性轨迹测量系统造成的长期漂移误差,可避免井下复杂工作环境对定位造成的干扰。