In specifying the interfaces by the crystallite theory of liquid, here is proposed to replace the excess boundary energy by the excess free energy. A correction is also made as to the previous procedure in determining the value of the orientational order parameter. With these modifications the theoretical results can be formulated in considerable agreement with the experimental rules, such as the Lindemann’s formula as to the melting point, the melting entropy, and the Andrade’s formula as to the coefficient of viscosity. Just above the melting point, more-over, we have expectation of some abnomalities of the specific heat and of the viscosity coefficient, due to the structural change more or less sharp there.

View full abstract

Mayer’s cluster method is developed in the crystal statistics analogously with the one in imperfect gases. The discussion is confined to the problem for the two cases, one for the two phase separation and another for the order-disorder transition. These Problems are treated just as the one for one-component imperfect gases, and the order parameters in binary crystal are calculated in the same way as is used to obtain the radial distribution functions in imperfect gases by Montroll and Mayer. By means of the chain approximation, the expression for the pair distribution function is obtained in the closed form which is somewhat like Zernike’s formula. And the transition temperatures are identified with the temperatures at which singular points of the distribution function begin to appear. It seems, however, that the results are not better than those obtained from Bethe’s approximation.

View full abstract

Thermodynamical considerations are given on the diffusion of ideal gases, sedimentation of dilute colloidal solution, dielectric anomalies of polar solution and intrinsic viscosity of macromolecule of non-spherical shape. In all these phenomena an important rôle is Played by differential equations of diffusion type which determine the distribution functions of molecules and the currents of the probability density. It is shown that the energy dissipation and the entropy increasing multiplied by absolute temperature are given by the works done by the external force and by the diffusion force respectivcly against the current of the probability density, and in particular the irreversible production of entropy multiplied by absolute temperature is given by the heat produced by the friction of the particles with the velocity equal to the current of the probability density. Finally, the theories by W. Kuhn and H. Kuhn and by one of the authors for the non-Newtonian viscosity of macromolecules are discussed and the equivalence of the final results of the two theories is demonstrated.

View full abstract

The phase transition and the crystal structures of the three modifications in cuprous bromide (CuBr) were studied by the X-ray powder method and the calorimetric measurement. The crystal structures in γ, β and α phases were determined to be face centered cubic, hexagonal and body centered cubic respectively. In the γ-phase, the structure belongs to the zincblende type, but it shows an anomalous change with temperature. This anomalous change of the structure was investigated by the same method as applied to the recent study of γ-CuI, and it was found that this anomaly is analogous to that of γ-CuI. The structures of β and α-CuBr were ascertained to be both the average structures closely resembling to those of β and α-AgI respectively.

View full abstract

The size distributions of Barkhausen impulses were obtained, at twelve different portions on the hysteresis loop of a silicon steel wire, with seven searchcoils, which had the same turn-density but different coil-lengths from each other. An experimental regularity was found in the relation between the distribution of impulse size and the coil-length. The distribution of domain size was calculated from this regularity, by making some assumption on the mechanism of Barkhausen effect. The main numerical results obtained are as follows; average length of domain: 0.345–5.20 mm; average volume; 0.298–6.40×10⁻⁵ mm³; average diameter: 3.32–3.96×10⁻³ mm; minimum average propagating velocity of the magnetic reversal: 3–50 m/sec.

View full abstract

The numerical values for domain size, obtained in Part I, were discussed, in comparison with the results by Bloch’s theory of ellipsoidal domain. It was concluded that the distribution of internal stress plays a leading role in the determination of the remaining position of domain boundary. The distribution of internal stress were determined from the standpoint of the probability theory. Domain size distribution formulae, showing the experimental regularties between the impulse size and the search-coil length, as described in Part I, were deduced from consideration on the relations between the distribution of internal stress and that of domain boundary.

View full abstract

The time interval distributions of the Barkhausen impulses were investigated. The experimental results show beautiful regularities, in contrast with Tyndall’s conclusion. An explanation for the experimental result was given, by assuming a simple mechanism for the reversal of domain magnetization. It was concluded that the magnetic reversal is not perfectly accidental, as is the case in the disintegration of radioactive substance. The reversal of domain magnetization needs always some accumulation of energy by some effects, either magnetic or of origins of other kinds.

View full abstract

In ferromagnetic substance, the origin of internal friction under low stress amplitude has been considered to be due to two kinds of eddy current. The first named macroscopic eddy current was studied by Brown and its theoretically predicted contribution to internal friction was known to be consistent with the experimental data. But the second named microscopic eddy current has not yet been investigated except in demagnetized state. In this paper, this loss is calculated as a function of magnetization assuming that magnetic anisotropy energy is negligibly small compared with the internal stress energy. The result shows that internal friction increases initially with increase of magnetization but decreases rapidly near the magnetic saturation. The experimental behavior of internal friction obtained previously can be qualitatively explained by this theoretical result.

View full abstract

Internal friction of Ni₃Fe is measured as a function of magnetization for different, stages of superlattice formation by using transversal vibration of about 500 c. p. s. For every stage of superlattice formation, the relation of internal friction vs. magnetization shows one or two maximums. This behavior can be explained by considering that one maximum is due to macroscopic and the other due to microscopic eddy current. By using the theoretical conclusion, on the microscopic eddy current which is given in the previous paper, the detailed behaviors of experimental relations can be explained by considering internal stress which is closely relate to the superlattice formation.

View full abstract

The magneto-thermoelectric power of iron single crystal was measured in a temperature region between room temperature and −195°C and the anisotropic constants (E_m)₁₀₀ and (E_m)₁₁₁ (which specify the effect along the direction [100] and [111], respectively) were calculated, at various temperatures. From thes results and those at high temperatures reported in the provious papers both the constants (E_m)₁₀₀ and (E_m)₁₁₁ were found to have the maximum values near room temperature and decrease gradually with decreasing temperature and may tend to zero at 0°K.

View full abstract

A. C. magnetization characteristics of a perminvar wire under tension were observed and discussed on the basis of the pipe-domain theory, the results of the discussion being compared with those based on the classical eddy current theory. It was found that the said domain theory would give a semi-quantitative interpretation of the a. c. data, and suggest the existence of an effect other than eddy currents. These results were, in essential, in agreement with the prediction by Williams and others on the a. c. magnetization characteristics of a single crystal of silicon iron. In connection with this, an account was given of an experiment based on the usual technique of estimation of the mean volume of domains and it was found that estimated sizes of the volume had little significance for the a. c. characteristics.

View full abstract

In cuprous oxide we discovered a new hydrogen-like absorption spectrum beside that in the previous work. Thus we have two groups of hydrogen-like energy levels, of which the one previously found seems to be due to a self-trapped electron and the other newly found on the other hand, seems to be due to an exciton and leads to the estimation of the static dielectric constant of cuprous oxide, being 9.5.

View full abstract

The author discusses the two-dimensional isostatical problem in the mechanics of either perfectly plastic or pulverulent body, obeying the maximum shear theory in “plane strain” or Coulomb’s plasticity condition in “plane stress” respectively, as a kind of gasdynamics of the hypothetical gas here introduced. This gas is non-viscous compressible and obeys the following pressure-density relation: p⁄ρ^γ=const., −1<γ<1, or p⁄logρ=const. The velocity of sound of the gas at rest is chosen to be zero in either case.
By applying the hodograph method, well-known in gasdynamics, to the gas flow, a general solution of the problem is obtained.
After considering simple waves and shocks of the gas flow, an extension of the analogy to plastic bodies of revolution is briefly mentioned.

View full abstract

The new method of solving the isostatical problem in the soil mechanics and theory of plasticity, which has been developed in the part (I) of this paper, is applied to practical problems, resulting in a demonstration of several plastic states of stress, slip lines, and isostatics.
There are illustrated, with mathematical expressions, figures, and photographs, slip lines on surface of a metal or soil produced by forcing a cylindrical punch into it, those in a plastic mass pressed between two rough parallel or inclined plates, regular markings on face of compressed prism of paraffin, and spiral cracks in safety glass disks broken under a concentrated load, etc.

View full abstract

Existing theories of the hydrodynamical stability of plane Poiseuille flow are divided into two groups by their quite different conclusions. Results attained by Lin and other earlier authors are that this flow is unstable for sufficiently large Reynolds numbers. On the other hand, Pekeris has obtained different results that the flow is stable for any value of the Reynolds number and that, in addition to the ordinary disturbances discussed by earlier authors, there exists another class of perturbation which is characterized by c_r→1 as αR→∞.
In this paper, a critical survey for these conflicting results is presented. It is shown that Pekeris’s first result arises essentially from the poor convergency of his series expansion of c, namely c=c₀+α²c₁+…, and that if this procedure is avoided, the existence of Lin’s stability limit is asymptotically confirmed. It is also found that Pekeris’s second prediction is erroneous.

View full abstract

The solution of trans-sonic flow is treated by the use of Laplace transformation in the hodograph method. As an example, the trans-sonic flow past a nearly, circular cylinder is calculated.

View full abstract

We have studied on the effect of temperature especially on the fluctuation of the strength of glass under uniformly increasing load with time on the center of glass plate suspended freely at the two ends. The region of temperature was between the room temperature and 300°C. μ(t), the probability of breakdown at the time t,is described as follows,
μ(t)=aexp\left[−\fracE₀(T)−βfkT\ ight]
Here, E₀(T) is the activation energy for breakdown when there is no applied load, f the load, β f the energy applied by external load, T the absolute temperature and k is the Boltzmann’s constant. According to the result of experiment, β is not constant but depends on the temperature, having a minimum at about 150°C. The magnitude of E₀ is some kcals/mol and increases with the temperature.

View full abstract

An uniform dilatational stress was produced in a thin layer of resin melted on a metallic tray by rapid cooling. This layer of resin holded on the tray was floated on the water and some mechanical shocks were given by electric discharges at two or three adjacent points near the bottom of the tray. The phenomena of the refractions of the cracks thus produced in the resin starting from each of these points were studied. At the places where α>90° (α, angle between the direction of the crack starting from one of the sources A′ and that of the shock wave from the other source A), the cracks refracted towards the point A, while if α<90° , the cracks refracted in the direction diverging from the point A. The velocity of propagation of these cracks was estimated from the relation between the distances travelled by the crack and the shock wave.

View full abstract

The author has found that when the microwave gas breakdown occurs, the direct current flows, without application of any direct voltage, in the external circuit from the outer conductor to the central wire of a cylindrical cavity containing gas.
An attempt has been made to explain this phenomenon by use of the diffusion theory of Herlin and Brown. The electron diffusion current density potential has been determined and thence the maximum electron density has been derived.

View full abstract

If the microwave gas breakdown once occurs, the microwave gas discharge continues even at the lower power and at the same time the direct current continues to flow, without application of any direct voltage, in the external circuit. From the observation of the length of the microwave glow appearing along the axis of cylindrical cavity, the direct current J has been shown to be proportional to E and nearly inversely proportional to P, where E in the maximum value of the microwave electric field intensity and P the gas pressure.

View full abstract