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Vol. 7, No. 3 (1948)

1948-02-05
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CONTENT
A STUDY OF THE IONOSPHERIC DATA OBTAINED AT WUCHANG-SEPT. 1946 THRU. DEC. 1947
P. H. LIANG, H. L. LUNG, S. WANG
1948, 12 (3): 1-17. doi: 10.7498/aps.7.1
Abstract +
Routine hourly observations of ionospheric characteristics have been taken at Wuchang since August 20. 1946. In this paper a general analysis of the data obtained from September 1946 through December 1947 is attempted. The diurnal and seasonal variations of ionization density and virtual height for all regular layers (E, F-l, F-2) are plotted in diagrams and briefly explained. Deviations from the normally recognized characteristics are discussed in more detail.Besides the normal characteristics, some special phenomena such as the occurrence of E2 near Sunrise and two major ionospheric storms are briefly described. Comparatively detailed study is made on the sporadic E ionization, with the conclusion that its percentage time of occurrence before mid-night is more than that after mid-night and that it is more prevalent in autumn than in any other season. Abnormally high E3 ionization was observed on October 10, 1946 when the Giacobini-Zinner comet was nearest the Earth. These facts indicate that metenrs are probably important agents in producing sporadic E jouization.
THERMODYNAMICS OF EQUILIBRIUM AND STABILITY
J. S. WANG
1948, 12 (3): 18-61. doi: 10.7498/aps.7.18
Abstract +
The dependence of the entropy of a homogeneous system on the composition is investigated with the help of a reversible adiabatic process which allows the change of composition by means of a semipermeable wall. The conditions of equilibrinm for phase transition and for homogeneous chemical reaction are derived in a new way. Next the criterion of minimum energy for constant entropy and volume is derived from the principle of increase of entropy. This criterion is then applied to obtain the conditions of equilibrium and stability with the help of Lagrange's multipliers. The conditions of stability are expressed in several alternative forms. Next the equilibrium properties of a binary system arc considered, and some types of phase diagram are explained by means of equations. The theory is extended to the general heterogeneous equilibrium of a system consisting of any number of independent components. A system of equations for the change of temperature, pressure, and composition are obtained and are solved by means of determinants. Next Planck's theory of a binary solution is extended to a solution consisting of several solnte components, with the same conclusion regarding the lowering of freezing point as for a binary solution. Finally Planck's theory on the number of coexisting phases for aone-component system is extended to a system consisting of k components with the result that a state with, σ coexisting phases is more stable than one with σ-1 phases: where σ is an integer not greater than k + 2.
A KINETIC THEORY OF TURBULENCE
GWOH-FAN DJANG
1948, 12 (3): 62-77. doi: 10.7498/aps.7.62
Abstract +
This paper deals with a method of treating problems of Turbulence from a kinetic point of view. Turbulence "temperature", "pressure", and "entropy" are first defined as state functions, and then the pressure and temperature are incorporated into the equations of motion. Turbulent flows through a circular pipe and between parallel planes are considered in some detail, while the problems of turbulence decay, turbulence structure, and correlation characteristics are briefly discussed. Practically in all cases, the constancy of the turbulence temperature is found to play an important role.
THE RECTIFYING CHARACTERS OF ORDINARY ELECTRIC BULBS
CHEN SHANG-YI, LIU PEN-HSUN
1948, 12 (3): 78-91. doi: 10.7498/aps.7.78
Abstract +
Rectified current derivable from an electric bulb when it is painted with Chinese ipk has been observed. The rectifying characters of twenty three ordinary electric bulbs made by eleven different companies were studied. It was observed that the polarity of the rectified current derived from the surface of the bulb depends on the nature of the bulb and an explanation to account for the phenomenon has been attempted. Results showing the relation between the output and the input, the effect of the position of the paint on the bulb, the temperature, the composition of the paint and the nature of the bulb are given.