Conductive microbead array detection based on eddy-current testing using SV-GMR sensor and helmhlotz coil exciter

金沢大学環日本海域環境研究センター生体機能計測研究部

Measurement and Visualization of Three-Dimensional Radial and Vectored Magnetic Field Distribution by Usue of the Magnetic CT Method

金沢大学環日本海域環境研究センター生体機能計測研究部

Performance of Repulsive Type Magnetic Bearing System Under Nonuniform Magnetization of Permanent Magnet

Permanent magnet bearing system utilizes the repulsive forces between the stator and rotor permanent magnets (PM) for the levitation of the system and it results a simplified axial control scheme. A repulsive type magnetic bearing system based on the above principle was fabricated in our laboratory. Material characteristics and the configuration of the permanent magnets are the central component for this type of bearing system. Due to aging or as both the magnets are repelling each other, there will be demagnetization of the permanent magnet, resulting the field distribution along the magnet\u27s periphery nonuniform. In this paper the effect of this magnetization nonuniformity on the performance of the bearing system has been studied

Optimum Structure of CT Probe and Spectral Components in 2-D Magnetic CT Method

金沢大学環日本海域環境研究センター生体機能計測研究部

Conductive Microbead Array Detection Based on Eddy-Current Testing Using SV-GMR Sensor and Helmholtz Coil Exciter

This paper describes the detection of both single and array conductive microbead (PbSn) by using a spin-valve giant magnetoresistance (SV-GMR) as a sensor and the Helmholtz coil as an exciter based on eddy-current testing (ECT). Experiments were performed to detect a single and array conductive microbead, with three models. Each model consists of 4 x 4 microbeads but the microbead diameter and pitch were slightly different for each array. The microbead radius was 125 μm and the pitch was 500 μm. The ECT method was used to estimate the position of the centers of the microbeads and the error in the measurement was plotted on a plane. A good level of position resolution has been achieved and the signals were quite clear

Optimum Structure of CT Probe and sｐectral Components in 2-D Magnetic Field Visualization Based on the Magnetic CT Method

The precise measurement of two-dimensional and three-dimensional magnetic flux distribution is indispensable for the development of magnetic machinery and device. The magnetic computed tomography (CT) method is proposed to visualize magnetic flux distribution. In order to determine the optimum structure of the magnetic CT probe, an evaluation model is employed to simulate the reconstruction accuracy of magnetic flux distribution. The spectrum of a distribution of magnetic field has been discussed of the components. As a result, the numerical simulation shows the optimum design of the multi layer CT probe

Wavelet-Based Processing of ECT Images for Inspection of Printed Circuit Board

This paper presents a wavelet-based image processing technique, which analyzes eddy-current testing (ECT) images derived by scanning printed circuit boards (PCB\u27s) with an ECT probe and automatically detects the existence and location of the defect. First, the undesired components contained in probe output are removed through two types of wavelet filtering. Then the comparison of two images obtained from reference and tested PCB\u27s are carried out to extract the signal due to the defect. In this paper, one-dimensional (1-D) wavelet is used only in the horizontal direction considering that the scanning of the probe is along that direction. In addition, the square norm of difference between original and processed signal is proposed as a criterion to keep the waveform of the defect peak as possible. The application examples of sample PCB\u27s reveal the effectiveness and problems of the given approach

Measurement and visualization of three-dimensional radial and vectored magnetic field distribution by use of the magnetic CT method

The measurement and visualization of three-dimensional radial and vectored magnetic field distribution based on the magnetic computed tomography (CT) method have been reported. Applying the method, it is possible to measure a surrounding magnetic field such as a spherical region by using a simple probe, which is not limited to the measurement of two-dimensional magnetic field distribution. It has been shown that the magnetic field distribution of a spherical surface covering a sample object can be visualized from the measured and calculated results with a spherical CT probe and CT reconstruction algorithm

Measurement and Visualization of Three-Dimensional Radial and Vectored Magnetic Field Distribution by Use od the Magnetic CT Method

The measurement and visualization of three-dimensional radial and vectored magnetic field distribution based on the magnetic computed tomography (CT) method have been reported. Applying the method, it is possible to measure a surrounding magnetic field such as a spherical region by using a simple probe, which is not limited to the measurement of two-dimensional magnetic field distribution. It has been shown that the magnetic field distribution of a spherical surface covering a sample object can be visualized from the measured and calculated results with a spherical CT probe and CT reconstruction algorithm