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Volume 32 (1980)
- Issue 12 Pages 721-
- Issue 11 Pages 671-
- Issue 10 Pages 585-
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- Issue 6 Pages 309-
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Volume 21 (1969)
- Issue 4 Pages 705-
- Issue 3 Pages 573-
- Issue 2 Pages 471-
- Issue 1 Pages 385-
Volume 21, Issue 2
Displaying 1-12 of 12 articles from this issue
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Susumu KATO, Sadami MATSUSHITA1969 Volume 21 Issue 2 Pages 471-478
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSWe investigate the effect of (J×B0) force on the tidal wave transmission where J is electric current and B0 the geomagnetic field. It is found that the force is considerably effective on any positive mode of the diurnal tide and the semi-diurnal tide except for the first semi-diurnal mode. The diurnal and semi-diurnal velocity oscillations of these modes, which are excited in the lower neutral atmosphere, cannot be transferred to the ionized atmosphere. An exception occurs, however, at the magnetic equator, where (J×B0) force is almost ineffective. The refractive index of the tidal wave is calculated for a simple model where the Coriolis force is ignored and (J×B0) is assumed to be uniform with longitude and latitude.View full abstractDownload PDF (748K) -
R. D. HILL1969 Volume 21 Issue 2 Pages 479-486
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThere are difficulties at present in accepting the theory that ELF sferics are mainly excited by cloud-to-ground discharges. Some discrepancies between theory and experiment are discussed. A new approach to the analysis of the frequency content of intra-cloud and cloud-to-ground discharges is taken by Fourier integrating the whole discharge. It is shown that the current-moment spectrum of the average intra-cloud discharge is approximately an order of magnitude larger than the average cloud-to-ground discharge spectrum in the important ELF sferics range from 10 to-100Hz.View full abstractDownload PDF (756K) -
Elmer L. SCHUMAN1969 Volume 21 Issue 2 Pages 487-493
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSData on the diurnal variation of the air-earth current and electric field obtained on the Carnegie ship cruises in 1928-29; at Thule, Greenland in 1958-59; and at the Amundsen-Scott Station at the South Pole in 1964 are compared from a numerical point of view. The normalized results are found not to agree. The analysis of the degree of significance of the disagreements reveals that different methods of normalizing yield drastically different interpretations; expressing the data as a percentage of the yearly mean renders the differences in the results insignificant at the 75% level while, if a daily mean is employed, those differences are found to be significant at the 90% level. The effects of various normalizing procedures on the dispersion of the data are also discussed. How unawareness of the errors arising even in simple averaging of data on atmospheric electric parameters leads to meaningless and often contradictory results is illustrated.View full abstractDownload PDF (534K) -
Mitiyasu OHNAKA1969 Volume 21 Issue 2 Pages 495-505
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSStress stability of the remanent magnetization of basalt under compression was experimentally tested. It was also examined, using a thick lava of basalt, whether the effect of compressive stress on remanent magnetization depends upon grain size of rock-forming ferromagnetic minerals. Intensity of IRM of the rocks shows an irreversible and remarkable reduction under axial compression. TRM and NRM decrease gradually as axial force is increased. Change of remanent magnetizations with respect to pressure is well expressed in a hyperbolic form: M(P)=M0/(1+βr·P), in the same manner as that of the initial magnetic susceptibility of volcanic rocks. TRM is more stable than IRM against pressure. For IRM, the stronger the applied magnetic field, the more stable the intensity and direction of remanent magnetization become with respect to pressure. It was found that the magnetically effective grain size of ferromagnetic minerals controls the stress stability of NRM as well as the intensities of TRM, the coercive force and the initial magnetic susceptibility.View full abstractDownload PDF (7300K) -
R. T. MERRILL, Naoto Kawai1969 Volume 21 Issue 2 Pages 507-512
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSA method using etching by HCl to test for self-reversal in rocks containing two or more magnetic minerals is illustrated by application to specimens from the Bucks batholith in Northern California. The etching results support the hypothesis that this batholith contains a self-reversed titanohematite and a normally magnetized magnetite.View full abstractDownload PDF (4445K) -
David J. Dunlop, Minoru Ozima, Hajimu Kinoshita1969 Volume 21 Issue 2 Pages 513-518
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe remanent magnetic properties of single-domain grains under uniaxial compression are easily interpreted by a graphical method based on the Néel thermal fluctuation theory, provided the stress σ and the magnetic field H are parallel. The change in remanence resulting from a change in magnetic field, stress, or temperature can be represented by the area swept out by a moving “blocking curve” on a graph of grain volume, v, versus microscopic coercive force, Hc. Applying or removing σ moves the blocking curve parallel to the Hc axis a distance 3λσ/Js. This graphical method is useful for visualizing pressureinduced remanence (PRM) and pressure demagnetization. If the grain distribution n(v, Hc) is known, it is also suitable for quantitative analysis. The theory explains some observed relationships between the intensity of PRM and the order in which σ and H are applied and removed, and predicts that these different types of PRM should have measurably different stabilities against AF, thermal, and pressure demagnetization.View full abstractDownload PDF (648K) -
Peter N. SHIVE1969 Volume 21 Issue 2 Pages 519-529
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe stress fields of edge and screw dislocations are analyzed to determine whether dislocations can exert independent magnetostrictive control over magnetization in magnetite. The stress-defined easy direction near a screw dislocation is described by a 45° helix or spiral about the dislocation line, although exchange and anisotropy energy suppress the spiral angle to less than 30°. The stress-defined easy directions near an edge dislocation are primarily normal to the dislocation line with a small region favoring magnetization parallel to the line. Single edge or screw dislocations can not control magnetization independent from the surrounding domain, even in the absence of a demagnetizing field, although both types will certainly produce local deflections of the spins within a domain.View full abstractDownload PDF (1080K) -
Yukio Hagiwara1969 Volume 21 Issue 2 Pages 531-541
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe magnetic field dragged by a constant convective motion in a conducting fluid was illustrated in the previous paper. When the interaction between magnetic fields and motions is strong, the motions distort magnetic lines of force, while the convection currents are in turn modified by the deformation of magnetic lines of force. We should therefore solve induction equation coupled with equation of motion in order to know the exact behaviors of magnetic lines of force as well as that of fluid streams. The author makes in this paper an attempt at solving the above equations for a model with a pair of convection. It turns out that the pattern of velocity streamlines is markedly distorted while the magnetic flux is deformed only slightly. Time-dependent deformations of both the stream lines and magnetic lines of force are graphically illustrated in series of figures in such a way that they can easily be compared with the results obtained on the assumption of the constant fluid motion.View full abstractDownload PDF (1098K) -
Yilmaz ISPIR1969 Volume 21 Issue 2 Pages 543-555
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThis paper is specifically aimed at the problem of obtaining magnetic fields of the highest possible uniformity at the center of coil systems of a number of given shapes, principally combinations of circular, square and solenoidal coil. The field uniformities of some previous arrangements and some new arrangements are discussed. The variations of the onaxis fields due to different coil arrangements are shown graphically (Fig. 3 and 10) near their centers and tabulated numerically along their axes of symmetry.View full abstractDownload PDF (907K) -
Ken-ichi MAEDA1969 Volume 21 Issue 2 Pages 557-567
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSDownload PDF (894K) -
IAGA Commission 2 Workiong Group No. 4 Analysis o1969 Volume 21 Issue 2 Pages 569-571
Published: June 20, 1969
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSDownload PDF (241K) -
1969 Volume 21 Issue 2 Pages 572
Published: June 20, 1969
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSDownload PDF (20K)
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