Influence of Magnetic Saturation of Iron-Core on Performance of Thyristor Phase Control Circuit

The influence of magnetic saturation of iron-core on the performance of thyristor phase control circuit with series RLC elements is described. The circuit is analyzed by applying an approximate model of three straight lines to the flux Φ vs. current i curve of the iron-core reactor. And the influence on waveforms, r.m.s. values, power factor and response are discussed

Experimental observation of shear thickening oscillation

We report experimental observation of the shear thickening oscillation, i.e. the spontaneous macroscopic oscillation in the shear flow of severe shear thickening fluid. The shear thickening oscillation is caused by the interplay between the fluid dynamics and the shear thickening, and has been predicted theoretically by the present authors using a phenomenological fluid dynamics model for the dilatant fluid, but never been reported experimentally. Using a density-matched starch-water mixture, in the cylindrical shear flow of a few centimeters flow width, we observed strong vibrations of the frequency around 20 Hz, which is consistent with our theoretical prediction.Comment: 4pages, 5 figure

Source mechanisms of twenty-six large, shallow earthquake (M_S ≧ 6.5) during 1980 from P-wave first motion and long-period Rayleigh wave data

Source mechanisms of 26 large shallow earthquakes are determined in terms of a double-couple point source with a correction for the nondirectional part of source finiteness by using P-wave first motions and long-period Rayleigh wave spectra recorded on WWSSN, IDA, and GDSN networks. The combined use of both data sets allows us to determine the double-couple mechanism uniquely in most cases. Constrained linear moment tensor inversion (M_(xz) = M_(yz) = 0) correctly determines the strike of the fault, but fails to estimate the dip, and underestimates the scalar moment. All thrust events along the deep-sea trenches analyzed in this study show nodal planes which dip perpendicular to the trench axis at an angle shallower than 45°. The fit to data of the double-couple inversion is comparable to that of the constrained moment tensor inversion. Using the phase spectra of surface waves we can detect a slow source process with an accuracy of about 10 to 20 sec

Measurements of Mantle Wave Velocities and Inversion for Lateral Heterogeneity and Anisotropy - 1. Analysis of Great Circle Phase Velocities

Long-period (100–330 s) fundamental-mode Love and Rayleigh waves have been processed to measure the great circle phase velocities for about 200 and 250 paths, respectively. The observations are inverted for regionalized phase velocities and for an even-order harmonic expansion of the lateral velocity heterogeneity. The regionalized inversions achieve a maximum variance reduction of about 65% and 85% for the Love and the Rayleigh wave data, respectively. The l_max = 2 inversions give a maximum variance reduction of about 60% and 90% for Love and Rayleigh waves, respectively. The l_max = 8 inversion does not make a large improvement in the fit. The Love wave phase velocities have more power in l = 4 and 6, relative to l = 2, than the Rayleigh waves. For both Love and Rayleigh wave data the sectoral component dominates the l = 2 harmonics, and this component is stable if we increase l_max from 2 to 6. Heat flow also has strong sectoral components (lm = 22), which are approximately in phase with those of the phase velocities. The l = 2 harmonics of the nonhydrostatic geoid are dominated by large zonal (lm = 20) and moderate sectoral components. The sectoral components are in phase with those of the phase velocities. The sectoral pattern of heat flow and phase velocity is controlled by high heat flow-low velocity of the East Pacific Rise and western North America, which is reinforced by low velocities in the antipodal region (Red Sea-Gulf of Aden-East African Rift). By contrast the geoid l = 2 pattern is dominated by geoid highs over the western Pacific subduction zones. A spherical harmonic expansion of regionalized phase velocities shows that they have l = 2 variations similar to those of the l_max = 2 nonregionalized inversions. This means that the regionalization approach is appropriate as a first step for studying lateral heterogeneity of the earth. However, the great circle phase velocities are not sufficient by themselves to uniquely locate the lateral heterogeneity. The same is true for free oscillation data. Regions of convergence have the interesting property of being slow for short-period waves and fast, faster than shields, for long-period waves

Measurements of mantle wave velocities and inversion for lateral heterogeneity and anisotropy - II. Analysis by the single-station method

Phase and group velocities of G_2, G_3, R_2 and R_3 (100-330_s) are measured by the single-station method and are inverted to give a spherical harmonic representation of the velocity lateral variation. Approximately 200 paths have been studied. The results are presented for degrees and orders up to 6. The even harmonics of the phase velocity representation are consistent with those obtained from great circle phase velocities (Paper I). The odd harmonics are less constrained and generally have larger standard deviations than the even harmonics. To suppress the poorly determined harmonics in the velocity contour maps we construct a filter which is derived from an inverse problem formulation. The filter reduces the amplitudes of regional variations, but does not change the overall pattern. The patterns of the regional variations are generally consistent with those obtained by regionalized inversion of great circle data (Paper I). The velocity maps show significant differences within oceans and continents. An analysis is made of correlations of surface wave velocities with heat flow and the non-hydrostatic geoid. The slownesses correlate well with heat flow for l = 1-6. The correlation peaks at l = 2 and 5. The geoid has an anticorrelation with the slownesses at l = 2 and 3, and a positive correlation from l = 4 to 6

Computer Aided Design of Thyristor Phase-Control Circuits

The paper presents the computer aided design (CAD) method, the program, the design and the experimental results of inverse parallel thyristor phase control circuits. The calculated values agree well with the measured. The CAD program contains the next two methods which are inquired carefully by authors, such as (i) the optimization by SUMT (Sequential Unconstrained Minimization Technique) method, and (ii) the combined use of the gradient and the cramp calculation methods

Analysis of Thyristor Phase Control Circuit with Parallel Resonance Elements

The phase control characteristics in a thyristor phase control circuit with parallel resonance elements indicate very interesting phenomenon. Several extreme values appear on the phase control curve. The phenomenon is different from the step-up one in a thyristor phase control circuit with series RLC elements which is interpreted as series resonance. To comprehend the circuit performance with those loads, it is necessary that the phenomenon on extreme value is physically clarified from other viewpoints. In this paper the performance in this circuit is studied from two viewpoints of a natural oscillation and a parallel resonance. Then, it is found that the performance depends on a natural frequency in thyristor conducting period and a parallel resonance frequency in thyristor non-conducting period. Therefore, the interesting phenomenon on extreme value is affected by the alternative of natural frequency or parallel resonance frequency

Generalized Analytical Program of Thyristor Phase Control Circuit with Series and Parallel Resonance Load

The systematic analytical method is reqUired for the ac phase control circuit by means of an inverse parallel thyristor pair which has a series and parallel L-C resonant load, because the phase control action causes abnormal and interesting phenomena, such as an extreme increase of voltage and current, an unique increase and decrease of contained higher harmonics, and a wide variation of power factor, etc. In this paper, the program for the analysis of the thyristor phase control circuit with a series and parallel connected load of series R-L-C circuit units, is been developed. By means of the program, the transient and steady state characteristics of the circuit can be calculated and then comparative study of various versions of circuits can be carried out systematically. The usefulness of the program is demonstrated by some numerical calculated examples