A measuring apparatus for bevel angle of cutleries has been devised by the writer. There is the Honda's paper-cutting sharpness tester which measures the durability as well as the initial sharpness of the edge. As far as the durability is concerned, the shape of bevel is of great importance. In general, the bevel is not a simple geometric wedge but a surface of complicated curvature. Using the new apparatus, the curvature and the edge along the whole length of the bevel can be examined by simple and easy manipulation with reflection of a narrow beam of parallel rays of light directed to the bevel. Safety razor blades have so far been examined revealing many characteristics hitherto unobserved.
Calculations of characteristics of doublet antenna with ribbon-shaped reflector, which were already reported, are applied to those with rectangular reflector. Numerical values of the latter are shown in the table, in which the rectangular reflectors are taken between 1λ (λ: wavelength) and 2λ in length and between IA and 3λ in width at intervals of 0.25λ in length or in width. From this table it is found that the directional characteristics in H-plane are affected by width rather than length, and that if a reflector is used in proper size, the radiator with such a reflector shows a flat directional characteristic curve over some angles in H-plane. For example, when the reflector is 1.6λ in width and 2λ in length, the radiator shows almost the same curve as that with infinitely extended reflector, which shows a flat curve over ±20 degrees in H-plane. The several directional characteristic curves shown in this table are verified by measurements. Results of measurement show very good agreement with those of computations. It is shown that these formulas can be used in case that the reflector is larger than 1λ in width or in length.
The size and refractive index of the crystals that constitute pearl essence are measured, and the relation between the luster of pearl essence and the optical properties of the crystal, namely reflection, transmission and scattering are studied. The crystals are of (2/100_??_3/100mm)×(2_??_8μ) rectangles with 70_??_80 mμ in thickness. The refractive index is 1.91>n>1.80. Theoretical calculation shows that the thickness of the crystal is adequate to the condition for the pearl essence to give out the lust of pearls.
Velocity of both longitudinal and transverse ultrasonic waves in polystyrene and polymethyl methacrylate is measured over the temperature range -60° to 90°C. Values of the bulk-modulus, shearing modulus, and Poisson's ratio are computed from the measurements. It is found that each curve of the velocity-temperature and of the moduli-temperature changes its slope at the temperature near the second order transition and that this temperature is independent of frequency. Measurements are also made on polymethyl methacrylate of different moisture contents. Water being absorbed, the shearing modulus becomes smaller but below room temperature the bulk-modulus becomes larger. Comparing with the density-temperature characteristics, this effect of absorbed water is explained as due to the decrease of the free volume and the plasticizer effect caused by the entry of water.
The dynamic Young's modulus and the piezoelectric constant of old timbers have been measured. They increase with time during the first about 300 years, then decrease gradually. The relation between the modulus and the constant is linear, indicating that both depend on the crystalline region content of cellulose fibers. The changes of the modulus and the constant with time can be explained by the crystallization and the heat dissociation of cellulose molecules that go on for long years.
In order to estimate accurately the allowable plate dissipiation of vacuuI_??_ tubes, some analyses are performed on the temperature distribution of a thin-walled hollow cylinder at a high temperature where the heat conduction through cylinder wall is negligibly small compared with the radiation from cylinder surfaces. The fundamental equation is deduced under the following assumptions. 1) Heat radiation follows Lambert's law. 2) Heat conduction through cylinder wall is negligible. 3) Total emissivity of the cylinder surfaces is independent of temperature. The equation is given in following formula. _??_ where A: total emissivity, a: radius of the cylinder, l: length of the cylinder, P(Z1): input energy Q(Z1): heat energy coming away from inner surface of the cylinder. This is a Fredholm's integral equation of the second kind. Two methods of numerical solutions of the equation are shown, and the results for some values of A and l/2a are tabulated. For example, TO/T5, the ratio of the maximum and minimum temperatures, is 0.990730 for A=0.2 & l/2a=1, and 0.900059 for A=0.2 & l/2a=8. It may be said that the temperature distribution is chiefly dependent on the geometrical dimensions of the cylinder but little dependent on the total emissivity of its surface. Short discussion is given on the method of obtaining the cylinder temperature availing so-called “Winkelverhältniss” which is deduced under the assumption that the cylinder has an uniform temperature distribution.