The phenomenon of the decrease in cutoff frequency of mesa-transistors at high injection level is investigated in detail. The emitter current dependence of cutoff frequency is expressed by the experimental formula _??_ where I0 is the characteristic current and η the index of rapidity of the decrease. The dependence of these parameters on the collector resistivity is given. In the case of mesa-transistors, the mechanism of the decrease in cutoff frequency can not be accounted for by the decrease in the effective mobility of minority carrier but by the saturation of current density in the collector region. It is also pointed out that the optimum collector resistivity can be determined if this phenomenon is taken into account.
Automatic pole figute X-ray recording apparatus which is provided with an improved integrating specimen holder and enables the measurement of metal sheets composed of large crystal grains up to 0.8mm dia. is described. Intermittent measurement eliminates errors that arise from incorrect time constant of the apparatus, and an accurate relation between grain size and limit of experiment is obtained. Several examples to which the integrating method was applied are shown. Generally, even with specimens composed of large crystal grains, complete pole figures can be obtained provided more than 400 crystal grains are within the region exposed to X-radiation. Application of the integrating method to X-ray diffraction of large crystal grain powder is also described.
Analyses on blackness of cylinder-type black body and temperature distribution inside a thinwalled hollow cylinder emitting radiant heat concerning the inter-reflection of thermal radiation are made on a luminous analogue computer (L. A. C.) developed by P. F. O'Brien with the following results. 1) Values of blackness of bottom and other parts inside a hollow black body of uniform temperature distribution agreed within 0.5% with those Nakaji's. 2) Even, in the above, when the temperature distribution is not uniform or heat emissivity is different from place to place, L. A. C. is useful for approximate calculation. 3) Result of computation of temperature distribution on inside surface of a thin-walled hollow cylinder emitting radiant heat agreed with that of Ito's calculation.
A measuring system for obtaining informations on surface texture is proposed. The measuring instrument is composed of two parts, “pattern” producer and analyzer. The former transforms. surface cross-section profiles into “patterns” which have analogue contour curves of the crosssections. The transformation is achieved by recording the surface profile on a photografic film in the form of variable-area. The “pattern” is mounted on the out-side of a large diameter glass tube. The latter is made up of a variable-area masking mechanism, rotatable mechanism, lense systems with light source and photocell. Feeding the “pattern” into the mechanism, one can obtain surface texture informations, i. e. average depth, depth of average line, center line average value, total height, form coefficient, loading curve and continuous average curve for arbitrary sampling length automatically or semiautomatically through optical process. The experiment conducted with an instrument made on trial shows that the above surface informations can be evaluated with accuracy of about 1% in error.
Precipitation process of nitride from α-iron is studied by measuring the period of vibration of torsion pendulum and the internal friction. The change in dynamic rigidity or in ΔM-effect measured at a temperature higher than Snoek's peak temperature was found to be proportional to the change in the height of Snoek's peak during quench-aging of Fe-0.02% N. This enables a quantitative study on the process of nitride precipitation by measuring the change in dynamic rigidity at temperatures higher than Snoek's peak temperature during aging, heating or cooling. On quenchaging of Puron loaded with 0.02% nitrogen, meta-stable nitride precipitate is found to form at a relatively lower temperature of 69°C or 98°C. A part of this meta-stable precipitate re-dissolves into matrix on heating up to 300°C or on aging at 147°C, then stable γ'-nitrides begin to precipitate. The rate of precipitation of meta-stable α"-nitrides becomes faster as the quenching temperature is higher.
Use of selenium rectifying element as the element of semi-conductor barrier capacitance (P-N junction) of parametron has been known. In this report, results of measurement on direct current characteristic, bias voltage dependence of barrier capacitance and Q (regarded as element efficiency), suitable exciting voltage, oscillation characteristic, exciting power and rate of change of barrier capacitance for supplied alternating voltage and also hystograms of scattering of these values are given. A flip-flop circuit by the use of selen parametron is devised; satisfactory operation of this circuit was confirmed.
The double-diffusion problem is solved both analytically and numerically. The analytic solution for the problem with surface rate limitation as the boundary condition is obtained by the use of Green's function. Impurity distribution profiles are presented graphically with evaporation rate constant as a parameter. It is suggested that the double-diffusion process is effective for the purpose of improving the high frequency characteristics of mesa-transistors. When all the other electrical parameters are set equal, base resistance becomes lower in the case of double-diffusion process than in the case of single-diffusion one. The method to evaluate quantitatively the degree of improvement is given and the numerical results are shown graphically.
Wear rates of flat specimens of brass and other metals sliding over the periphery of a rotating disc of cast iron, stellite or tool steel are measured. Reproducible wear values are obtained under unlubricated and cetane-lubricated conditions. The wear values when lubricated by cetane with e. p. additive or by refrigerator oil decrease gradually with the number of runs of the turns of the disc and become almost steady at the tenth run. These final values together with other observed values, both expressed in specific wear K, are summarized in a table in which one can perceive the effects of lubricant, sliding speed, material combination, annealing and working of the material, continued grinding of the rotating disc, etc. on the wear rate. The table includes also the results on bearing steel and three plastic materials. Micrographs of deformation produced on an annealed brass specimen by a cast iron rotating disc are shown.
In chapter 1, the peculiarity of powder (soil) mechanics is considered and it is concluded that the stress in powder mass is, if possible, to be measured without inserting any probe. A photoelastic method using no probe is proposed. In chapter 2, outline of the procedures of this method is explained and the following are made known: (1) Isoclinics can be observed in the same way as in ordinary photoelastic experiment; (2) Distribution of brightness caused by the photoelastic effect in less than one fringe is observed, the equibrightness lines corresponding to ordinary isochromatics; (3) A sort of striped pattern resulted from fibrous structure in powder mass is observed by a circular polariscope, the direction of the stripes coinciding with that of the major principal stress in powder mass; (4) Measurements by Babinet Compensator and Tank's method are also possible. In the next report, the following will be given; (1) Photoelastic properties of glass powder mass; (2) Technical problems in experimental procedure; (3) Utility of this method in engineer ing field.