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| 1.
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Roy, Debabrata P. ; Akiyama, Yosuke ; Yamada, Sotoshi ; Iwahara, Masayoshi ; 山田, 外史 ; 岩原, 正吉
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This paper has reported the development and performance of a flux-concentration type linear induction motor (FCLIM) utilizing the effect of flux-concentration by eddy currents. In the developed FCLIM, the slot-leakage flux is reduced and
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as a result more flux is concentrated into the air gap. The key element of the FCLIM is the conducting plate inserted between the exciting coils in each slot. Thrust characteristics of conventional tubular LIM and FCLIM are compared using the equivalent circuit parameters. Though some losses are occurred in the plate, the overall efficiency of FCLIM is better at higher output force.
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| 2.
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Taniguchi, T. ; Nakamura, K. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; 山田, 外史 ; 岩原, 正吉
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This paper presents an image processing method for eddy-current testing for the detection of the defects with a specific orientation. The method utilizes the fact that a line-shaped signal is, through the Fourier transform, mapped onto a
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line passing through the origin and perpendicular to the orientation of the original signal. Hence, nonseparable fan filters is used to select the frequency components corresponding to the defects orientated in a Specific direction. This approach enables more precise control of the extraction characteristics of signals compared to the iterative application of one-dimensional (1-D) filtering in the vertical and horizontal directions, in which the shape of the pass band is restricted to a geometry made from squares. The effectiveness of the proposed method is shown by a demonstration using a metallic sample with a defect aligned in a number of directions.
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| 3.
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Mukhopdhyay, S.C. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; 岩原, 正吉 ; 山田, 外史
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This paper has investigated the possibility of applying nondestructive evaluation technique for finding the defects in electroplated materials. Planar meander and mesh type magnetic sensors have been considered and their relative
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performance have been compared based on a single criterion that the effective area of the material surface covered by each type of sensor is same.
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| 4.
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Mukhopdhyay, S.C. ; Iwahara, Masayoshi ; Yamada, Sotoshi ; 岩原, 正吉 ; 山田, 外史
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For the last few years the authors have been involved in the design and development of different topologies of magnetic current limiter (MCL). The small scale laboratory models have been fabricated and experiments were conducted. The
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simulated performance obtained from the tableau approach based on lumped parameter model shows discrepancy with the experiment. This paper describes the necessity of electromagnetic field computation which clearly shows the discrepancy between the observed and the simulation results, which can be attributed to a non uniform flux distribution in the core.
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| 5.
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Kacprzak, D. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; 山田, 外史 ; 岩原, 正吉
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This paper presents simulated amplitude and phase characteristics obtained during the inspection of printed circuit board by an eddy-current testing probe. The simulation is based on the "two-components" nature of the output signal.
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Amplitude and phase characteristics, obtained during the experimental inspection and simulation, are presented.
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| 6.
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Mukhopadhyay, S.C. ; Iwahara, Masayoshi ; Yamada, Sotoshi ; Dawson, F.P. ; 岩原, 正吉 ; 山田, 外史
概要:
Different topological configurations for a passive magnetic current limiter consisting of a permanent magnet and saturable core are discussed in this paper. The models for a series/parallel biasing mode, and a single/three phase supply
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system have been fabricated and the experiments have been carried out for the performance evaluation. Using tableau method, the transient performance of different models has been simulated. The feasibility of applying the current limiter for the protection of power semiconductor devices in moderately low voltage applications is investigated.
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| 7.
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Ohji, T. ; Kano, M. ; Mukhopadhyay, S.C. ; Iwahara, Masayoshi ; Yamada, Sotoshi ; 岩原, 正吉 ; 山田, 外史
概要:
A permanent magnet bearing (MB) system utilizing the repulsive forces operating between the stator and rotor permanent magnet for levitation and radial control has been fabricated in our laboratory, The consistency of the permanent magnet
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magnetization effects the continuous steady-state and dynamic performance of the system. Since both the magnets are repelling each other, there will be demagnetization of the magnetization of the permanent magnet. Due to demagnetization or ageing or manufacturing asymmetry, the field distribution may not be uniform along the periphery of the magnet. In this paper the effect of this magnetization non-uniformity on the performances of the bearing system has been studied.
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| 8.
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Hossein, Bayani ; Nishino, Masanobu ; Yamada, Sotoshi ; Iwahara, Masayoshi ; 山田, 外史 ; 別所, 一夫
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In this paper we propose a model to reproduce a PCS pattern eddy current testing signal based on 3D FEM package and scanning simulation. In this method we consider some common PCB elements as test pieces while a simple Meander-type
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coil is utilized as excitation coil above the elements. Numerical solution to the above problem with the help of a 3D FEM provides the magnetic flux density in the region above the PCB test elements. Shifting the test element's position step by step and repeating the numerical calculation for each of the test elements new positions, the scanning process of a PCB test piece is simulated. Analysing and smoothing the magnetic field data from all of the aforementioned steps provide the final PCB pattern signal. Image processing technique was applied to obtain the PCB part image.<br />Special Issue on 16th MAGADA Conference
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| 9.
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Kakikawa, Makiko ; Hosono, R. ; Hashimoto, S. ; Iwahara, Masayoshi ; Yamada, Sotoshi ; 柿川, 真紀子 ; 岩原, 正吉 ; 山田, 外史
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| 10.
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Chomsuwan, K. ; Fukuda, Y. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; Wakiwaka, H. ; Shoji, S. ; 山田, 外史 ; 岩原, 正吉
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| 11.
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Mukhopadhyay, S.C. ; Iwahara, Masayoshi ; Yamada, Sotoshi ; 岩原, 正吉 ; 山田, 外史
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| 12.
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Hagino, T. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; 山田, 外史 ; 岩原, 正吉
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Toyama, H. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; Roy, Debabrata P. ; Miya, K. ; 山田, 外史 ; 岩原, 正吉
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| 14.
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Okada, T. ; Hussien, A. ; Ohji, T. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; 山田, 外史 ; 岩原, 正吉
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Yamada, Sotoshi ; Gooneratne, Chinthaka ; Iwahara, Masayoshi ; Kakikawa, Makiko ; 山田, 外史 ; 岩原, 正吉 ; 柿川, 真紀子
概要:
金沢大学理工研究域電子情報学系<br />出版社照会後に全文公開|許可を得て登録
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| 16.
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Yamada, Sotoshi ; Gooneratne, C. ; Chomsuwan, K. ; Iwahara, Masayoshi ; Kakikawa, Makiko
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This paper describes a new application of a spin-valve type giant magnetoresistance sensor in the biomedical field. The
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hyperthermia treatment, based on the hysteresis loss of magnetite under external ac fields, requires determination of the content density of magnetite injected inside the body to control the heat capacity. We propose a low-invasive methodology to estimate the density of magnetite by measuring magnetic fields inside the cavity. For this purpose, we investigated the relationship between the density of magnetite and the magnetic fields, and developed a needle-type magnetic probe with a giant magnetoresistance sensor for low-invasive measurement. The experimental results demonstrate the possibility of estimating the low-concentration density of magnetite injected into the body. © 2008 American Institute of Physics.
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| 17.
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Yamada, Sotoshi ; Iwahara, Masayoshi ; Fukuda, Y. ; Taniguchi, T. ; Wakiwaka, H.
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Gooneratne, C. P. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; Kakikawa, Makiko ; Matsumoto, Y.
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Utilization of magnetic nanoparticles in biomedicine has seen an unprecedented growth in recent years. The ability to accurately estimate magnetic nanoparticles inside small areas of the body provides an advantage in
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hyperthermia therapy, a form of cancer treatment. This paper concentrates on a novel giant magnetoresistance (GMR) needle-type sensor to detect and estimate low concentration magnetic fluid inside minute agar cavities injected with magnetic fluid. Theoretical analysis, experimental results and information on the fabricated GMR needle-type sensor are reported. The experimental results show a favorable agreement to the analytical analysis, supporting the potential use of the GMR needle-type sensor in hyperthermia therapy<br /><Special Issue> Asia-Pacific Symposium on Applied Electromagnetics and Mechanics (APSAEM08)
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| 19.
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Iwahara, Masayoshi ; Muramoto, Hiroshi ; Miyazawa, Eijiro
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金沢大学理工研究域電子情報学系<br />Recently, a remarkable advance is seen in the application on the laser equipment, particle beam acc
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elerator, and pulsed X-ray equipment. These apparatus requires an intermittent high voltage or large current power source to do work, and those power sources are required to have a high reliability and a durability. For this reason, a power supply using passive circuit elements is often used for these apparatus. A multistage circuit made by a saturable reactor and a capacitor is a good example of pulse power supply. In this paper, a discussion is given on the optimal circuit parameter and the optimal operation mode of a fundamental two-stages pulse compression circuit. Analysis for the two-stages LC circuit is developed by use of the state variable method, and it is assumed that a saturable reactor has a magnetization characteristics approximated by a polygonal line with two segments. Defining evaluation indices on voltage boost ratio G_v, current gain G_j and pulse width compression ratio ζ, the optimal operation mode was determined by these indices, and the optimal circuit parameter was obtained. As the results, it is shown that the C_1 equals to 10×C_2 in case of two reactors, with a same value, and it is obtained that G_v=0.35, G_j=0.26 and ζ=0.66. It is also shown that the reactor loss is a very sensible to the performance of this circuit.
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| 20.
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Mukherjee, A. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; Mukhopadhyay, S.C.
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Fast transient analysis of a passive fault current limiter (FCL) using permanent magnets can be done by direct numerical solution of a single non-linear differential equation. The non-linear B-H excursion that is caused by hysteresis
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is incorporated in the computation using a transient hysteresis model. Rational fractions are used to represent the parent hysteresis loop curves. Since the method uses preconstructed expressions as applicable to FCL schemes only, computation time required is less.
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| 21.
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Kacprzak, D. ; Taniguchi, T. ; Nakamura, N. ; Yamada, Sotoshi ; Iwahara, Masayoshi
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This paper presents a novel eddy-current testing (ECT) sensor for the inspection of printed circuit board (PCB), which detects trace damages on PCB conductors. The sensor is composed of a meander-exciting coil and three solenoid pick-up
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coils. Application of three pick-up coils increases the speed of the inspection process. Information about defects can be extracted either from an amplitude or a phase of a signal obtained during the inspection. A visualization process was provided using the amplitude data. In this paper the structure of the ECT sensor and principles of detection as well as experimental results are presented.
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| 22.
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Calman, S. ; Dawson, F.P. ; Yamada, Sotoshi ; Iwahara, Masayoshi
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This paper shows that flux nonuniformity in a passive magnetic fault current limiter softens the transition characteristics from the saturated to the unsaturated state. Soft transition characteristics lead to higher core losses
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and a derating in the maximum nominal operating current. Flux uniformity is improved by using a combination of extended magnets and an anisotropic saturable core. The use of distributed permanent magnets or an extended magnet leads to larger differential inductance ratios.
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| 23.
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Taniguchi, T. ; Kacprzak, D. ; Yamada, Sotoshi ; Iwahara, Masayoshi
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This paper presents a wavelet-based image processing technique, which analyzes eddy-current testing (ECT) images derived by scanning printed circuit boards (PCB's) with an ECT probe and automatically detects the existence and location
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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's 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's reveal the effectiveness and problems of the given approach.
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| 24.
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Mukhopadhyay, S.C. ; Iwahara, Masayoshi ; Yamada, Sotoshi ; Dawson, F.P.
概要:
There is an increasing need in power system applications for fault current limiter, to limit the fault current in semiconductor devices and switchgear. These fault current limiters must be reliable, compact and inexpensive. This
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paper reports the result of an investigation of the characteristics of a Fault Current Limiter (FCL) consisting of a steel core and permanent magnet. Design criteria are presented. The FCL characteristics are simulated using a Tableau approach and the simulation results have been compared with experimental result.
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| 25.
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Roy, D. ; Fujiyoshi, A. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
This paper has reported the eddy current and secondary-core flux density distributions of a flux-concentration type linear induction motor (FCLIM) based on the effect of flux-concentration by eddy currents. In the developed FCLIM,
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the slot leakage flux is reduced and as a result more flux is concentrated into the air gap. Thrust characteristics are also determined using the parameters of the equivalent circuit. It is observed from the calculated and experimental results that the developed FCLIM has better performance than that of the normal type tubular LIM.
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| 26.
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Chomsuwan, K. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
This paper describes the improvement on the defect detection performance of printed circuit board (PCB) inspection based on the eddy-current testing (ECT) technique with the multispin-valve giant magnetoresistance (SV-GMR) sensor. To
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obtain the ECT signal in the same scanning line, SV-GMR sensors are mounted on the exciting coil in the same column parallel with the scanning direction. Harmonic analysis based on the Fourier transform is used to analyze the signal from the SV-GMR sensor in order to increase scanning speed. Then signal averaging is applied to the ECT signal in order to improve the signal-to-noise ratio. Experimental results are performed to verify the inspection performance.
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Yamada, Sotoshi ; Chomsuwan, K. ; Fukuda, Y. ; Iwahara, Masayoshi ; Wakiwaka, H. ; Shoji, S.
概要:
This paper proposes an eddy-current testing (ECT) probe composed of a spin-valve giant magnetoresistance (SV-GMR) sensor and a meander coil for the inspection of bare printed circuit board. The SV-GMR sensor serves as a magnetic sensor for
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the ECT probe to sense the variation of the magnetic field distribution occurred on the printed circuit board. The SV-GMR sensor is used specifically to detect the changing magnetic field distribution occurred at the defect point. The characteristics of the proposed probe are discussed in this paper. The comparisons of signal-to-noise ratios obtained from ECT probe with SV-GMR sensor and with solenoid coil verify that the applying of SV-GMR sensor to the ECT probe can improve the PCB inspection results.
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| 28.
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Kacprzak, D. ; Taniguchi, T. ; Nakamura, N. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
This paper presents a theory of the superposition of two signal components formed during the inspection of printed circuit board (PCB) by an eddy-current testing probe composed of a meander-exciting coil and a solenoid pick-up coil.
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Proportion of these two components effects the amplitude and the phase of the output signal. Characteristic changes of the phase characteristic, obtained from calculations and observed during the real inspection of PCB, are explained.
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| 29.
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Mukhopadhyay, S.C. ; Dawson, F.P. ; Iwahara, Masayoshi ; Yamada, Sotoshi
概要:
The fabrication and development of a novel compact three phase magnetic current limiter consisting of permanent magnets (PM) and saturable cores is described in this paper. Simulation results using the tableau approach are presented for
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varying operating conditions. Experimental results are in good agreement with the simulation results. The proposed current limiter has potential in moderately low voltage applications.
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| 30.
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Iwahara, Masayoshi ; Mukhopadhyay, S.C. ; Yamada, Sotoshi ; Dawson, F.P.
概要:
So far the reported literature on the magnetic fault current limltcr(FCL) arc based on series biasing mode in which the flux due to Hue current flows through the permanent magnet, As a result there ta a high possibility of demagnetization
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of the permanent mngnet. A passive Cault current limiter lu a combination or passive elements such a.s permanent magnet and saturablc core. Permanent mngnet Is used to bias (he core, In order to avoid severe demagnetization of permanent magnet, in this paper we have Investigated the performances of passive fault current limiter based on permanent magnet nnd saliirablc core In parallel biasing mode, the functional characteristics have been analyzed by Tableau approach and the simulation results arc presented. The experimental results for a small scale prototype model are also presented for verification.
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| 31.
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Yamada, Sotoshi ; Katou, M. ; Iwahara, Masayoshi ; Dawson, F.P.
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This paper presents a new eddy-current probe composed of a micro-planar mesh coil and meander coil. The probe can be use
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d to detect the existence and the size of cracks in metallic structures. Experimental results for the sensed output voltage of this device are presented. The output signal is shown to have a discrete nature. Also, the results show that the signal strength is weak and that an offset voltage exists. Improved probe characteristics are obtained by connecting two mesh coils in series, stacking the coils on top of each other and orienting the two coils 180° apart.
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| 32.
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Chomsuwan, K. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; Wakiwaka, H. ; Shoji, S.
概要:
High-density double-layer printed circuit board (PCB) inspection based on the eddy-current testing (ECT) technique is proposed in this paper. The ECT probe, which consisted of a planar meander exciting coil and spin-valve giant
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magnetoresistance (SV-GMR) sensor array, is used for this propose. Defects on both the top- and bottom-layer of the high-density double-layer PCB are examined by the ECT technique with scanning over either the top or bottom layer. The characteristics of the proposed ECT probe for high-density double-layer PCB inspection are studied. The inspection results of the high-density double-layer PCB model verify that applying the ECT technique enables identification of the defects of both the top and bottom layer with one-side scanning.
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| 33.
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Mukhopadhyay, S.C. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
To overcome the directional properties of a planar meander-type sensor, a new planar micromagetic sensor having mesh-type configuration is reported in this paper. Analytical models are usually used for the characterization of the
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planar-type sensors. Sensors having mesh-type configuration have been fabricated for the derivation of the optimum coil pitch.
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| 34.
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Roy, D. ; Saruhashi, D. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
This paper has reported the fabrication and development of a novel flux-concentration type linear induction motor (LIM) based on the effect of flux concentration by eddy currents. In the developed LIM, the leakage flux between
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the yokes is reduced and as a result more flux is concentrated into the air gap. It is observed from the calculated results using equivalent circuit parameters and the experimental results that the flux-concentration type LIM (FCLIM) has better thrust-characteristics compared to that of normal type tubular LIM.
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| 35.
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Somsak, T. ; Chomsuwnan, K. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
This paper describes the detection of both single and array conductive microbead (PbSn) by using a spin-valve giant magn
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etoresistance (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.
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| 36.
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Bayani, H. ; Nishino, M. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
In this paper we propose a model to reproduce printed circuit board (PCB) pattern eddy current testing signals based on 3D finiteelement method (FEM) package and scanning simulation. In this method we consider some common PCB
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elements as test pieces while a simple Meander-type coil is utilized as excitation coil above the elements. Numerical solution to the above problem with the help of a 3D FEM provides the magnetic flux density in the region above the PCB test elements. Shifting the test element's position step by step and repeating the numerical calculation for each of the test elements new positions, the scanning process of a PCB test piece is simulated. Analysing and smoothing the magnetic field data from all of the aforementioned steps provide the final PCB pattern signal. Image processing technique was applied to obtain the PCB part image.
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| 37.
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Nishimura, T. ; Miyamoto, Y. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
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
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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.
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| 38.
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Ohji, T. ; Mukhopadhyay, S.C. ; Iwahara, Masayoshi ; Yamada, Sotoshi
概要:
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
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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's periphery nonuniform. In this paper the effect of this magnetization nonuniformity on the performance of the bearing system has been studied.
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| 39.
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Nishimura, T. ; Miyamoto, Y. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
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
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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.
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| 40.
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Mukhopadhyay, S.C. ; Ohji, T. ; Iwahara, Masayoshi ; Yamada, Sotoshi ; Matsumura, Fumio
概要:
Repulsive Type Magnetic Bearing using permanent magnet for the lévitation and radial control makes the system cheap and
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simplified control scheme. But the system is prone to disturbance in the absence of any active control. This paper reports on the application of H°°control for robust stabilization and configuration of permanent magnet resulting in improved stiffness characteristics for disturbance attenuation in the radial direction of repulsive type magnetic bearing system. A laboratory prototype model and the controller around digital signal processor have been developed and experiments are carried out.
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| 41.
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Yamada, Sotoshi ; Katou, M. ; Iwahara, Masayoshi ; Dawson, F.P.
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This paper presents results pertaining to image data obtained from a planar meander-mesh coupled coil type ECT probe. The image data makes it possible to detect not only the existence of a defect but also to extract detailed
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information regarding the nature of the defect, such as its position, shape, length, and direction. In order to recognize a defect distinctly, we have fabricated the high sensitive planar coil which can be used to image a 2-D representation of the ECT signal. The relationships between the image pattern and defect shape are discussed.
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| 42.
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Yamada, Sotoshi ; Nakamura, Kazunori ; Iwahara, Masayoshi ; Taniguchi, T. ; Wakiwaka, H.
概要:
The detection of imperfections (such as disconnections, chipping cracks, nonuniformity in thickness and short-circuit, etc.) on the traces of bare printed circuit board (PCB) using a new high-sensitive eddy-current testing
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(ECT) probe has been reported in this paper. The ECT technique is composed of planar meander type exciting coil and a new multiple solenoid sensing coil. The image processing method is used to analyze the results. This paper has discussed the structure of the new probe, the characteristics of the measurement technique to inspect high-density PCB with narrow conductor-width. And the possibility of detecting micro-metal ball has been explored.<br />A new application of eddy current testing techniques for investigating trace defects on printed circuit boards is proposed, A test probe consisting of a meander type exciting coil is used to induce eddy currents. The following three experiments are conducted: measuring the induced signal when a circuit trace is cut; measuring the induced signal for a number of traces placed in parallel and with a cut in the centre trace; measuring the induced signal for two back to back right angle traces. The experimental results reveal that it is possible to clearly detect defects and that the signal response obtained is strongly associated with a particular defect pattern. The signals obtained from a high density patterned board have a complicated signal signature and are therefore difficult to interpret. This complexity can be avoided by comparing the signal signature of a known good board with a defective board. The difference signal gives a clear indication of a trace defect.
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| 43.
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Yamada, Sotoshi ; Chomsuwan, K. ; Hagino, T. ; Tian, H. ; Minamide, K. ; Iwahara, Masayoshi
概要:
This paper describes the detection of conductive microbeads (PbSn) based on eddy-current testing (ECT) technique. High-frequency magnetic field applied to the conductive microbeads enables spin-valve giant magnetoresis-tance (SV-GMR)
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sensor to detect the magnetic fields occurred from eddy currents flowing in the conductive microbeads. In this paper, analysis of these magnetic fields by an analytical method is discussed and compared with experimental results.
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| 44.
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Dawson, F.P. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
The purpose of this paper is to experimentally verify the current limiting characteristics of a two material magnetic device consisting of a ferrite and permanent magnet material. A resonant pulsed excitation source and a 60 Hz ac
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source are used to test the characteristics of the device. The experiments confirm that there is a saturated and unsaturated inductance operating region and a current limiting and loss of current limiting kneepoint.
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| 45.
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Hussien, A.A. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
Many applications of the single-axis controlled repulsive-type magnetic bearing have been proposed earlier. However, both passive and active magnetic bearings are employed in most of such systems. In this paper, a new permanent magnet (PM)
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repulsive-type micromass measurement system is developed. The repulsive forces of the PM section are used effectively to keep the radial direction stable where the electromagnets, control circuits, and peripheral devices needed for controlling the unstable direction are simplified. The configuration, control design, and operating characteristics of the proposed system have been presented.
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| 46.
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Yamada, Sotoshi ; Gooneratne, Chinthaka Pasan ; Iwahara, Masayoshi ; Kakikawa, Makiko
概要:
Due to its biocompatibility, magnetic fluid or nanoparticles have been used inside the body to deliver medicines or to act as self heating agents to kill cancerous tumors. The estimation of magnetic fluid inside tumors is critical in
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hyperthermia therapy. This paper reports a unique needle-type GMR sensor fabricated for the purpose of confirming the presence and location, and estimating low-concentration magnetic fluid inside the body, in a minimally invasive way. Theoretical analysis is presented for detecting and estimating magnetic fluid in vivo. Experiments are performed initially to detect magnetic fluid in trays with embedded cavities followed by detecting and estimating magnetic fluid inside pieces of agar. The results show that the needle-type GMR sensor has good potential to be used in clinical applications such as hyperthermia therapy in cancer treatment.
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| 47.
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論文
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Young, S. ; Dawson, F.P. ; Iwahara, Masayoshi ; Yamada, Sotoshi
概要:
This paper investigates the inductance versus current characteristics of a two-material and a three-material magnetic cu
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rrent limiter. The two-material device consists of a NdFeB permanent magnet, a high saturation flux density magnetic material, and a high saturation flux density magnetic pole piece placed on both sides of the magnet. The three-material device consists of a NdFeB permanent magnet, a high saturation flux density magnetic material, and a low saturation flux density material. Finite-element results for the three-material device agree with the results obtained using design equations. In contrast, the results obtained for the two-material device show that the transition current is overestimated and that the ratio of the maximum safe current and transition current, as well as the unsaturated inductance is underestimated. Extending the magnet beyond the adjoining surfaces improves the sharpness of the transition characteristics when the ratio of the core length to the core width is large. © 1998 American Institute of Physics.
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| 48.
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Ohji, Takahisa ; Mukhopadhyay, S.C. ; Iwahara, Masayoshi ; Yamada, Sotoshi
概要:
Two types of magnetic bearing systems employing permanent magnets to be used for vertical-shaft and horizontal-shaft mac
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hines, respectively, have been designed and fabricated in our laboratory. In this article we report a comparative evaluation of (i) the permanent magnet configuration and its effect on radial disturbance attenuation, (ii) magnetic losses and their effect on energy storage, and (iii) the off-state position of the rotor magnet in two types of bearing systems. Experimental results are presented. © 1999 American Institute of Physics.
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| 49.
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Iwahara, Masayoshi ; Yamada, Sotoshi
概要:
Mathematical model of hysteresis is introduced, and it is characterized to analyze highly saturable magnetic equipment on the effect of specific paramenters. Using this mathematical model, performance of magnetic pulse
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compression circuit is nemerically analyzed.
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| 50.
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論文
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Chomsuwan, K. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
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門<br />This paper describes the improvement on the defect detection performance of printed cir
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cuit board (PCB) inspection based on the eddy-current testing (ECT) technique with the multispin-valve giant magnetoresistance (SV-GMR) sensor. To obtain the ECT signal in the same scanning line, SV-GMR sensors are mounted on the exciting coil in the same column parallel with the scanning direction. Harmonic analysis based on the Fourier transform is used to analyze the signal from the SV-GMR sensor in order to increase scanning speed. Then signal averaging is applied to the ECT signal in order to improve the signal-to-noise ratio. Experimental results are performed to verify the inspection performance. © 2007 IEEE.
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| 51.
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Ohji, T. ; Mukhopadhyay, S. C. ; Iwahara, Masayoshi ; Yamada, Sotoshi
概要:
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門<br />Permanent magnet bearing system utilizes the repulsive forces between the stator and ro
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tor 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's periphery nonuniform. In this paper the effect of this magnetization nonuniformity on the performance of the bearing system has been studied.
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| 52.
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論文
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Yamada, Sotoshi ; Katou, Masaki ; Iwahara, Masayoshi ; Dawson, Francis P.
概要:
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門<br />This paper presents results pertaining to image data obtained from a planar meander-mes
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h coupled coil type ECT probe. The image data makes it possible to detect not only the existence of a defect but also to extract detailed information regarding the nature of the defect, such as its position, shape, length, and direction. In order to recognize a defect distinctly, we have fabricated the high sensitive planar coil which can be used to image a 2-D representation of the ECT signal. The relationships between the image pattern and defect shape are discussed. © 1996 IEEE.
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| 53.
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論文
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Nishimura, T. ; Miyamoto, Y. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
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門<br />The measurement and visualization of three-dimensional radial and vectored magnetic fie
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ld 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. © 2005 IEEE.
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| 54.
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Hussien, Alaa A. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; Okada, Tomotada ; Ohji, Takahisa
概要:
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門
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| 55.
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Yamada, Sotoshi ; Chomsuwan, K. ; Iwahara, Masayoshi
概要:
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門<br />This paper describes the applications of spin-valve type giant magnetoresistance sensor
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(GMR) for nondestructive evaluation. One is the eddy-current testing (ECT) probe which enables us to inspect micro defect and to detect micro conductors. The proposed ECT probe was applied to the inspection of bare printed circuit board and the recognition of micro solder bead for IC surface mounting package. Another is the measurement of the density of magnetic fluid injected in living body for the hyperthermia treatment. For this purpose, the needle type GMR probe was developed. The experimental results verify the possibility of the proposed system. © 2006 IEEE.
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| 56.
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Nishimura, T. ; Miyamoto, S. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
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門
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| 57.
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Somsak, T. ; Chomsuwan, K. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
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門
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| 58.
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Nishimura, T. ; Miyamoto, S. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
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門
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| 59.
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Chomsuwan, Komkrit ; Yamada, Satoshi ; Iwahara, Masayoshi
概要:
岩原, 正吉
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| 60.
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Yamada, Sotoshi ; Chomsuwan, Komkrit ; Hagino, T. ; Tian, H. ; Iwahara, Masayoshi
概要:
岩原, 正吉
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| 61.
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Javora, Radek ; Iwahara, Masayoshi ; Yamada, Sotoshi
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| 62.
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論文
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Chomsuwan, K. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
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門<br />This paper describes bare printed circuit board (PCB) inspection based on eddy-current
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testing (ECT) technique with high scanning speed. A high-frequency ECT probe composed of a meander coil as an exciting coil and the spin-valve giant magnetoresistance (SV-GMR) sensor was fabricated and is proposed. The ECT probe was designed based on crack inspection over flat surface, especially suitable for microdefect detection on high-density bare PCB. The ECT signal detected by the SV-GMR sensor was acquired by high-speed A/D converter for applying the signal processing based on digital technique. Harmonic analysis based on Fourier transform was used to analyze the ECT signal at fundamental frequency in order to increase inspection speed and this technique allowed the ECT probe to scan bare PCB, with high sampling frequency and with high-spatial resolution inspection. Experimental results verified the possibility and the performance of the proposed PCB inspection system based on ECT technique. © 2007 IEEE.
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| 63.
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論文
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Yamada, Sotoshi ; Chomsuwan, K. ; Fukuda, Y. ; Iwahara, Masayoshi ; Wakiwaka, H. ; Shoji, S.
概要:
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門<br />This paper proposes an eddy-current testing (ECT) probe composed of a spin-valve giant
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magnetoresistance (SV-GMR) sensor and a meander coil for the inspection of bare printed circuit board. The SV-GMR sensor serves as a magnetic sensor for the ECT probe to sense the variation of the magnetic field distribution occurred on the printed circuit board. The SV-GMR sensor is used specifically to detect the changing magnetic field distribution occurred at the defect point. The characteristics of the proposed probe are discussed in this paper. The comparisons of signal-to-noise ratios obtained from ECT probe with SV-GMR sensor and with solenoid coil verify that the applying of SV-GMR sensor to the ECT probe can improve the PCB inspection results.
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| 64.
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論文
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Chomsuwan, K. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; Wakiwaka, H. ; Shoji, S.
概要:
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門
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| 65.
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論文
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Yamada, Sotoshi ; Chomsuwan, K. ; Hagino, T. ; Tian, H. ; Minamide, K. ; Iwahara, Masayoshi
概要:
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門<br />This paper describes the detection of conductive microbeads (PbSn) based on eddy-curren
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t testing (ECT) technique. High-frequency magnetic field applied to the conductive microbeads enables spin-valve giant magnetoresis-tance (SV-GMR) sensor to detect the magnetic fields occurred from eddy currents flowing in the conductive microbeads. In this paper, analysis of these magnetic fields by an analytical method is discussed and compared with experimental results. © 2005 IEEE.
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| 66.
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論文
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Yamada, Sotoshi ; Fujiki, Hisashi ; Iwahara, Masayoshi ; Mukhopadhyay, S. C. ; Dawson, Francis P.
概要:
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門<br />A new application of eddy current testing techniques for investigating trace defects on
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printed circuit boards is proposed, A test probe consisting of a meander type exciting coil is used to induce eddy currents. The following three experiments are conducted: measuring the induced signal when a circuit trace is cut; measuring the induced signal for a number of traces placed in parallel and with a cut in the centre trace; measuring the induced signal for two back to back right angle traces. The experimental results reveal that it is possible to clearly detect defects and that the signal response obtained is strongly associated with a particular defect pattern. The signals obtained from a high density patterned board have a complicated signal signature and are therefore difficult to interpret. This complexity can be avoided by comparing the signal signature of a known good board with a defective board. The difference signal gives a clear indication of a trace defect. © 1997 IEEE.
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| 67.
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論文
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Nishimura, T. ; Miyamoto, Y. ; Yamada, Sotoshi ; Iwahara, Masayoshi
概要:
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門<br />The precise measurement of two-dimensional and three-dimensional magnetic flux distribu
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tion 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. © 2005 IEEE.
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