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Volume 19, Issue 5
Displaying 1-6 of 6 articles from this issue
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Contributed Papers
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D. Suga, A. Shinjo, S. Nisikawa, Y. Chiba1995 Volume 19 Issue 5 Pages 872-874
Published: October 01, 1995
Released on J-STAGE: November 07, 2007
JOURNAL OPEN ACCESSThe present paper deals with the effect of a static magnetic field on the viability, motility, and velocity of thawed cattle sperm collected from four bulls and stored in straws. Each sample was exposed continuously for 0, 1, 2, 4, 6, or 8 hours to magnetic field of 1000 Gauss at 4°C, 20°C, or 38°C. A solution of 2% Eosin Bluish was used to determine the sperm's viability. The motility and velocity were determined by means of the CellSoft computer-assisted sperm motion analysis system (CASA). The viability of sperm exposed to the magnetic field was higher than that of non-exposed sperm at 4°C (8 hours), 20°C (6 and 8 hours), and 38°C (2 and 4 hours). Magnetic field exposure at 38°C for one hour also enhanced the motility of the sperm. However no significant differences were found in the velocity of sperm as a result of the treatment. These findings suggest that the effectiveness of the magnetic field is high for sperm viability, but only slight for motility, and negligible for velocity.View full abstractDownload PDF (227K) -
O. Miyashita, K. Ohniwa, T. Fujimaki, M. Morikawa1995 Volume 19 Issue 5 Pages 875-878
Published: October 01, 1995
Released on J-STAGE: November 07, 2007
JOURNAL OPEN ACCESSPower electronic converters, such as dc choppers and inverters, generate a pulsating current. The magnetic flux lags behind the current, because of eddy currents in the solid part of an electrical machine. This paper analyzes magnetic flux transients, which are closely related to such delayed responses caused by eddy currents in iron cores, and proposes a method for estimating magnetic responses on the basis of an equivalent circuit model for an iron-cored winding. The model parameters can be determined by measuring the de resistance and testing the impedance at a commercial frequency. The calculated results agree well with the experimental results. The method can be used to estimate the electromagnetic response of windings such as those used in electrical machines.View full abstractDownload PDF (271K) -
T. Muramatsu, M. Michijima, M. Kadono, T. Fujine1995 Volume 19 Issue 5 Pages 879-884
Published: October 01, 1995
Released on J-STAGE: November 07, 2007
JOURNAL OPEN ACCESSThe temperature dependence of the initial permeability (μi) for FeAlSi evaporated films was studied in the presence of external stress. The uniaxial magnetic anisotropy (Km) due to magnetostriction was separately evaluated from crystalline magnetic anisotropy (Ku). For a film of standard composition (4.8 wt%Al, 9.6 wt%Si, bal. Fe),Km (1.6 × 102 J/m3 at -10°C) gradually became smaller and went below zero at 110°C; on the other hand, Ku increased from 10 to 50 J/m3 in the temperature range of -10°C and 110°C. Km and Ku almost equally affected the magnetic softness of the film. And μi had a peak of 5400 at 40°C, at which the sum of Km and Ku reached a minimum. It was found that the frequency characteristics of a thin-film magnetic head with both a small magnetostriction constant of the order of 10-7 and a small residual thermal stress of 3 × 108 N/m2 as tensile stress were 1≅2 dB better than those of a head with no residual stress, above 20 MHz.View full abstractDownload PDF (419K) -
T. Hidaka, T. Yamamoto, T. Yoneyama1995 Volume 19 Issue 5 Pages 885-888
Published: October 01, 1995
Released on J-STAGE: November 07, 2007
JOURNAL OPEN ACCESSPreparation and magnetic properties of Sm2Fe17Nxα-Fe composite magnets obtained by HDDR method have been investigated. Sm-Fe alloys prepared by arc melting were rapidly quenched at a surface velocity of Vs=50 m/s. These as-quenched ribbons, containing 6∼8 at%Sm, possessed a Sm-Fe phase of TbCu7-type. After HDDR treatment, a Th2Zn17-type Sm-Fe phase and an α-Fe phase were observed. Sm2Fe17Nx+α-Fe composite magnets were obtained by subsequent nitrogenation.
Nitrogenated Sm8Zr2Fe90 powders exhibited high magnetic properties with σm=115 emu/g and HcJ=12.4 kOe, after applying magnetization field of 50 kOe. These powders showed σr/σm ratio of 0.63 without demagnetization correction.View full abstractDownload PDF (227K) -
S. Kainuma, H. Takahasi1995 Volume 19 Issue 5 Pages 889-892
Published: October 01, 1995
Released on J-STAGE: November 07, 2007
JOURNAL OPEN ACCESSGalvanostatically controlled pulsed electrodeposition was used to prepare Co/Cu multilayers. The magnetoresistance of [Co(Cu)/Cu] × 150 films grown on vacuumdeposited Cu and Permalloy films was measured as a function of the Cu layer thickness and a value of the order of 6% was obtained at room temperature. The peak was centered at a Cu thickness of about 2.5 nm. A high-angle X-ray diffraction pattern did not show any satellite peak. This observation suggests that the interfaces are fairly rough on an atomic scale. It may be assumed that this roughness is mainly due to the dissolution of newly deposited Co in Cu solution.View full abstractDownload PDF (266K) -
K. Hamada, E. Hirota, I. Ishida, A. Okada, K. Uchiyama, N. Kaminaka1995 Volume 19 Issue 5 Pages 893-897
Published: October 01, 1995
Released on J-STAGE: November 07, 2007
JOURNAL OPEN ACCESSMagnetic domain structure change under a magnetic field across the length of an MR element (transverse magnetization) was observed in detail by Lorentz electron microscopy for a sample whose size was the same as that of the actual element, l0 × 100 μm2. Various magnetic field were applied through the objective lens of the electron microscope utilized. During the magnetization process, the element retained a single magnetic domain structure while non-uniform rotation of the magnetization took place within the domain. The transfomation from the nonuniform to uniform rotation of the magnetization upon the application of a longitudinal bias field was confirmed.View full abstractDownload PDF (640K)
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