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Vol. 7, No. 2 (1947)

1947-01-20
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CONTENT
GENERAL THEORY OF THE QUASI-GHEMICAL METHOD IN THE STATISTICAL THEORY OF SUPERLATTIGES
C. N. Yang, Y. Y. Li
1947, 11 (2): 59-71. doi: 10.7498/aps.7.59
Abstract +
The generalization of the quasi-chemical method of Fowler and Guggenheim in the statistical theory of superlattices made by one of the authors is extended to a binary alloy of any composition. The formulae are very similar to those for the composition 1:1. The alloy AuCu3 is treated in more detail.
FACTORS AFFECTING THE FREQUENCY DEVIATION IN REACTANCE-TUBE FREQUENCY MODULATION CIRCUITS
Chai Yeh, Y. K. Tzu
1947, 11 (2): 72-80. doi: 10.7498/aps.7.72
Abstract +
In reactance-tube frequency modulation circuits, the fractional frequency deviation is expected to vary with the phase shift constants of the modulator and the Lf/Cf ratio of the tank-circuit of the oscillator. The way in which the frequency deviation is affected by these factors is discussed theoretically. Experimental checks are made, Two types of circuits are studied, the inductive and the capacitive reactance-tube circuits. It is found that within the straight portion, of the operating characteristic of the tube, the agreement is fairly satisfactory.
THE FOURIER AND THE NEW POINT DIAGRAM SYNTHESES IN X- RAY CRYSTALLOGRAPHY
S. H. Yu
1947, 11 (2): 81-95. doi: 10.7498/aps.7.81
Abstract +
A newly developed synthesis of X-ray data for crystal analysis, called the point diagram synthesis, is compared with the classical Fouriers. The fundamental assumption in the method s first explained. A correlation matrix of index 10 is then quoted. Some mathematical properties of the correlation matrices, that is, the absolute convergence, and the h- and μ-summation rules are described and illustrated. The method is next applied in parallel with the Fouriers to an arbitrary structure along with its two component structures. The crystal NaCl is next studied, using the actual experimental data. It is shown that on the basis of exactly the same experimental data the inormation given by the two types of syntheses are entirely different. Conclusions about the method drawn in the previous articles are then discussed in the light of the new studies and approved once more.
THE LAMINAR MIXING MOTION OF TWO INCOMPRESSIBLE GASES
P. Y. Chou
1947, 11 (2): 96-101. doi: 10.7498/aps.7.96
Abstract +
Equations determining the velocity and density distributions within the mixing region of two incompressible gases with different densities are set up, their temperatures being assumed to be the same. For incompressible mixing the total number of gas molecules per unit volume is constant, although the density of the gaseous mixture varies from point to point due to diffusion of matter. As an illustration we consider the plane jet and steady motion. The boundary layer method of approximation can still be applied. The boundary of the jet is shown to be the same as that for one fluid. The solution of the problem then depends upon the numerical value of the coefticient of viscosity of the mixture which is a function of the number of molecules of each constituent gas in the unit volume. The present method of investigation is applicable to the cylindrical and half jets and also to the case where the two gases are at different temperatures.
LARGE DEFLECTION OF A CIRCULAR CLAMPED PLATE UNDER UNIFORM PRESSURE
Wei-Zang Chien
1947, 11 (2): 102-107. doi: 10.7498/aps.7.102
Abstract +
The problem of large deflection of a clamped circular plate under uniform pressure is studied by the method of successive approximation in terms of the parameter representing the ratio of the center deflection to the thickness. The tedious numerical computations, involved in Way's power series solution are thus avoided. The yielding condition at the edge checks very well with the experimental results given by McPherson, Ramberg and Levy. The method may be easily extended to any other boundary conditions and loading details.