Excitations In Poly Research Articles

The Chandlerian Period of minimum excitation

Up to the present, the Chandlerian Period has been defined as the mean period of the revolution of the pole around its mean position. However, as the motion of the excitation pole does not contain the Chandlerian component, we can determine the length of the Chandlerian Period under the condition that the motion of the excitation pole attains a minimum after elimination of the Chandlerian component. It is calculated as 416 (mean solar) days. It means the period deduced from the angular velocity of the pole around the instantaneous excitation pole, and is able to match better those deduced from the theory of the internal constitution of the Earth. The calculated results using the recent data of ERP with a high precision show that the Chandlerian Period in this sense seems to have a reality.The main results are shown in the Figure on the next pape.This paper was published in full form in the Journal of the Geodetic Society of Japan, 33 (1987) pp.97–100.

An Investigation of Carrier to Noise Ratio in Perpendicular Magnetic Recording with Narrow Track-Width Head

Actual examples are given to show that low head impedance is extremely important in narrow track-width heads for high-density perpendicular magnetic video recording and reproduction, and that it strongly affects the wideband frequency characteristics and the noise level of the head. A main pole excitation probe-type head (MPD), with 7 μm track width, was fabricated to compare the dependence of frequency band and noise characteristics on head impedance. With high sensitivity and low impedance, the MPD head had a very favorable CN ratio of 54.5 dB, suggesting that in the future it will provide significant advantages for widebanddigital recording.

A.C. diesel–electric drive system using consequential pole changing

The paper describes the development of a commutatorless diesel-electric drive system which uses an alternator and induction motors as the drive elements. The system provides a set of discrete final motor drive speeds at a fixed alternator drive speed, and so may be regarded as an electrical `gearbox?, a feature of the scheme being that, during normal operation, gear selection is carried out by pole changing the alternator excitation winding. Pole changing of the alternator output winding and the induction-motor stator winding is also used, but is a consequence of changing the alternator excitation pole number, and switching at full power level between the alternator and motors is thereby entirely avoided. The paper includes a sample design for a traction system having a continuous rating of 3600hp. The prediction of the performance of the sample design is substantiated by experimental results taken on a simplified laboratory model of the system.

Electric Excitation and Disintegration of Nuclei. I. Excitation and Disintegration of Nuclei by the Coulomb Field of Positive Particles

General formulas for the cross section for the ${2}^{l}$-pole excitation (or disintegration) of a nucleus by the electric field of a non-relativistic positively charged projectile have been obtained by using the Born approximation; the finite size of the nucleus has been taken into account. For electric dipole and quadrupole excitation a more accurate evaluation has been made in which the initial and final states of the charged projectile are described by the exact coulomb field wave functions.The cross section for electric ${2}^{l}$-pole excitation of a nucleus by the field of a charged projectile is proportional to the corresponding photo-excitation cross section; the proportionality factor may be interpreted as the number of virtual electric ${2}^{l}$-pole quanta in the field of the charged projectile. In the electric dipole case, the cross section for the inelastic scattering of a charged projectile is shown to be proportional to the cross section for the production of continuous x-rays by deflection of the projectile in a coulomb field. Thus a relation is established between the virtual quanta representing the coulomb field of the projectile and the real quanta of the x-ray spectrum corresponding to the scattering process.The theory of electric transitions has been applied, in some detail, in a discussion of two cases in which it seems likely that these transitions play a significant role. These two cases are (1) the inelastic scattering of deuterons and (2) the electric break-up of the deuteron when it collides with a target nucleus.