涡流检测技术在金属表面缺陷检测中的应用

本文对无损检测的发展概况进行了介绍,并对涡流检测的原理进行了详细的阐述。基于涡流及其趋肤效应原理,对等效阻抗法、低频涡流检测、高频涡流检测、多频涡流检测、扫频涡流检测、阵列涡流检测几种常用的涡流检测方法进行了介绍。以金属回转体表面缺陷检测为例,结合具体的试验方案、软硬件要求、试验结果数据分析,描述了涡流检测的实际应用效果。     

涡流阵列检测技术

涡流阵列(Eddy Current Arrays)技术是近10年内出现的一项新的涡流检测技术,它是通过涡流检测线圈结构的特殊设计,并借助于计算化的涡流仪强大的分析、计算及处理功能,实现对材料和零件的快速、有效地检测.     

一种新型涡流检测法及其检测效果

涡流检测法是非常常用的金属材料缺陷检测的无损检测方法,为了改进传统涡流检测法难以微型化的不足,提出了一种新型涡流检测法,分别用小永磁体和高精度磁传感器代替了传统涡流检测法的激励线圈和接受线圈.通过试验和数值模拟相结合的研究方法,对新型涡流检测法的原理及检测效果进行了研究.结果表明,新型涡流检测法的检测原理可行,检测装置...     

涡流检测钢轨表面新方法

新的钢轨涡流检测器是使用中切合实际情况的一种新方法。它可以通过一种旋转芯涡流检测,和串联及横向安排探测线圈来精确地检测轨头和轨底损伤性缺陷。图1是这个设备中不同探头的组合和缺陷检测系统。旋转芯涡流检测方法如图2所示。使用一个有圆周槽的金属圆盘,将芯子嵌入槽中,因此,首先在盘周感应生成一次涡流,而当涡流围绕芯子流动时又产生二次涡流。许多根芯不一定布置在同心圆上。     

国外钢轨涡流检测技术现状

叙述了涡流检测法原理和利用涡流法检测钢轨表面缺陷的几种方法；同时介绍了国外几个钢轨生产厂研究开发的涡流检测装置。     

轧辊裂纹的涡流探伤检测技术

简要介绍了轧辊裂纹涡流探伤检测的原理、涡流检测系统的基本结构和实际运用技术要求。     

多频励磁脉冲涡流钢材检测技术

论述了涡流检测技术的物理基础，介绍了单频涡流技术的特点及局限性，以及多频励磁脉冲涡流检测技术近年来的进展和应用于钢材无损检测的广阔前景。     

钢材涡流检测中的信号分析与处理

钢材涡流检测中检测线圈的输出信号十分复杂,对此信号进行准确的分析与处理,是获得高精度和高可靠性检测结果的基础,本在对涡流检测线圈输出信号进行详细分析的基础上,提出了正交双通道相干检测波的数学分析模型和相应的信号处理电路,在涡流探伤仪的设计和钢材探伤应用中满意的效果。     

金属材料的涡流无损探伤(连载) 第三章 检测方法和检测线圈

本章将以管材、棒材为例讨论涡流探伤的检测方法和检测线圈。§3.1.检测方法3.1.1.检测线圈的功能和组成在涡流探伤中,检测线圈应具备如下功     

涡流检测技术在梅钢轧辊检测中的应用

介绍了轧辊涡流探伤仪的技术特点,系统组成和该技术在梅钢热轧板厂中的应用。指出涡流探伤技术是检测轧辊表面质量的重要手段之一,可以有效地减少轧辊磨削量。     

Minimally invasive saphenous vein harvesting: endothelial integrity and early clinical results

Eddy current effects induced by switched gradients in proximal conducting structures are traditionally reduced by applying preemphasis currents whose amplitudes and decay characteristics must be set to offset the eddy current fields. We present an expeditious, localized, and quantitative method for mapping and adjusting the parameters for eddy current compensation. Mapping is based on analysis of projections as used in the fast automatic shimming technique by mapping along projections (FASTMAP). Adjustment methods are demonstrated in high-field horizontal bore systems. The proposed localized eddy current mapping technique may also be used for localized measurements in situations where asymmetric conducting structures may cause nonlinear eddy current fields, such as in interventional MRI and open magnet designs.     

涡流探伤在钨丝生产中的应用

介绍了涡流探伤的基本原理和设备组成,重点阐述了涡流探伤在钨丝生产中的应用,并对涡流探伤的各种参数设定及影响探伤结果的因素进行了分析和探讨,指出涡流探伤技术是检测钨丝表面质量的有效手段,展望了该技术在金属丝材加工领域的应用前景。     

TP2铜管涡流探伤的研究及应用

近年来随着空调、冰箱行业产品的发展及激烈的市场竞争,TP2铜管作为冷凝器和蒸发器的原材料,其性能要求也日益提高,将涡流探伤作为TP2铜管生产过程的质量监控手段是一个必然趋势,结合TP2铜管涡流探伤的应用情况,简述了涡流探伤的基本原理和设备组成,重点介绍了检测线圈的作用和在TP2铜管上涡流探伤的效果,并对涡流探伤的参数设定及校准进行了分析,以提高TP2铜管产品的成品率,降低生产成本。     

Gradient Coil Design in Permanent Magnet MRI

Based on target field method, the article designs gradient coils for a permanent MRI magnet model. By simulating, winding and testing, the result verifies the validity and feasibility of target field method used in gradient coils design of permanent magnet MRI; moreover, shielded coils can restrain eddy current and can be designed based on target field method easily. The simulated results show that the effect of restraining eddy current is notable. So, the permanent magnetic MRI gradient coil can be designed by target field method. Gradient coils generate the linearly gradient field; and shielded coils restrain the eddy current.     

宝钢轧辊涡流检测技术的应用和发展

针对宝钢从国外引进的轧辊涡流探伤设备出现的问题着重介绍冷轧辊表面缺陷的涡流检测原理，应用，存在问题及解决办法。     

钢管涡流探伤可靠性分析

从原理上分析了钢管涡流探伤中采用穿过式自比差动线圈对纵向裂纹类缺陷检出率低的原因,并通过试验进行了验证。阐述了影响钢管涡流探伤可靠性的因素,提出了改善钢管涡流探伤可靠性的几点建议。     

Characterization of and correction for eddy current artifacts in echo planar diffusion imaging

Magnetic resonance diffusion imaging is potentially an important tool for the noninvasive characterization of normal and pathological tissue. The technique, however, is prone to a number of artifacts that can severely affect its ability to provide clinically useful information. In this study, the problem of eddy current-induced geometric distortions that occur in diffusion images acquired with echo planar sequences was addressed. These geometric distortions produce artifacts in computed maps of diffusion parameters and are caused by misalignments in the individual diffusion-weighted images that comprise the diffusion data set. A new approach is presented to characterize and calibrate the eddy current effects, enabling the eddy current distortions to be corrected in sets of interleaved (or snapshot) echo planar diffusion images. Correction is achieved by acquiring one-dimensional field maps in the read and phase encode direction for each slice and each diffusion step. The method is then demonstrated through the correction of distortions in diffusion images of the human brain. It is shown that by using the eddy current correction scheme outlined, the eddy current-induced artifacts in the diffusion-weighted images are almost completely eliminated. In addition, there is a significant improvement in the quality of the resulting diffusion tensor maps.     

焊接钢管在生产线上的涡流探伤

涡流探伤具有连续、快速、检测灵敏度高的特点，适合于焊接钢管在生产线上的连续检测。本文概述了本厂采用EEC数字型涡流探伤仪在焊管生产线上应用情况。     

平面型线圈阵列电涡流传感器阻抗分析

炼钢生产过程中,结晶器钢水液位和炉渣厚度的动态测量对生产高质量钢至关重要,采用电涡流传感器测量钢水液位和渣层厚度具有很多优点。对电涡流传感器的阻抗分析是设计电涡流测量系统的基石。本文以炼钢过程中结晶器钢水液面和渣层厚度分布测量为研究对象,采用平面型线圈阵列传感器,通过建立三维电磁场物理模型并用数值计算的方法求解电磁场,...