A practical radioactive snow gauge of a new design with a telemetering system has been made. The principle of measurement is based upon the mass absorption of the gamma rays by deposited snow. The gamma rays are emitted from artificial radio-isotope Co60 suspended at a suitable height above the ground. The counting rate of pulses by a G-M counter, which is specially prepared ethyl formate quenched one, buried just under the ground surface indi-cates the water equivalent of snow deposited over that spot. The output current of the rate-meter converted from the pulse is used to operate the Morse code system of a radio trans-mitter. This enables very accurate remote of snowfall in isolated mountain areas. General arrangement of the telemetering system of the gauge is shown in a figure. Preliminary tests of the system in Sapporo were sufficiently successful. The new gauge with necessary improvements will be set at a suitable point in the Lake Shikaribetsu basin for practical use in ascertaining the volume of water which will become available to the Shikaribetsu hydroelectric plants.
It is desirable that angle of inclination of the supporting fork of wheels rooling on sand should agree with the direction of the combined force of resistances offered by the sand and the load. But since the direction of the combined resistance varies with the state of the sand, the shape of the rim and the velocity, it is required to change the inclination of the fork according to the working condition.
Studies on deformation of Al and mild steel plates pierced by a bullet of 12.2φ×25mm with velocities of 230_??_490m/sec are given. In the case of Al plates, the pierced hole is characterized by shear fracture. The de-lormation is the smaller, the larger the velocity of the bullet for a given thickness of the plate and the thinner the plate for a given velocity. The time repuired for piercing seems to affect the magnitude of deformation. Annealed plates show larger deformations when compared with as-rolled plates. In the case of mild steel plates, there are two patterns; one is the clean shear fracture and the other the shear fracture accompanied with tensile fracture. The deformation is the smaller, the larger the velocity for the same pattern of the fracture. Annealing seems to make the deformation slightly larger. In the case of eutectoid steel plates, in spite of the considerable deformability by slow punching, no plastic deformation is observed and brittle-type fracture appears on the back of the plate.
Report is made on the propagation of fractures in mild steel plates caused by impact of high speed bullets with observations on twinning of ferrite grains and distortion of twin lines. (1) On the propagation of fracture For as-rolled plates, resistance to fracture is larger in the direction of the rolling than in the direction perpendicular to it. This difference is lost by annealing. In annealed plates, the crack is apt to take its path along pearlite grains. In as-rolled plates, crack with bifurcation is observed. (2) On the deformation after twinning Micro-photographs show that the twinning is completed at the moment of impact followed by intense distortion of twin lines with the flow of ferrite grains. From this fact, it is denied that the twinning would proceed simultaneously with the brittle-type fracture.
A stable and precise extensiometer for strip temper pass mill has been constructed and successfully used as a measure of operation with the accuracy of ±0.2% in extension. Strip speeds before and after rolling are picked up by photoelectrical device and converted to two frequencies. The beat frequency of the two is at first obtained and the ratio of the best frequency to one of the original frequencies, namely the percentage of the extension, is directly indicated by a counting rate ratio meter. Detailed explanation of the meter and the result of practical operation are given.
The orientation of deposited silver by evaporation on several crystal surfaces, of silver bromide is studied by electron diffraction, making a comparison with the case of photolytic silver. The results well agree in most cases with that of photolytic silver provided that the deposited silver hardey impairs the silver bromide crystals. The mechanism of silver separation is made known from equilibrium conditions of the ionic space charge and the electronic energy levels. This idea successfully explaines the experimintal results, suggesting the presence of the defects formed by interstitial silver ions and the complexes supposed to consist of two silver vacancies and one bromine vacancy, just before the formation of Schottky defects. A speculation is made on the structure sensitive properties of silver bromide.
Electrolytically polished surfaces of Cu-Be (Be 0.5, 1, 2, 3%) and Cu-Mg (Mg 0.5, 1.5%) alloys are studied by electron diffraction and the results are summarized in a table. The fact that the electrolytically polished surfaces of 2% and 3% Be-Cu alloys are composed of r phase is of interest. This fact can be considered to have resulted by the selective dissolution of a phase of the alloys. On such surface BeO-film is produced selectively by oxidation in open air. The surfaces oxidized at 400_??_500◊C have the characteristics of secondary electron emis-sion as good as those of the surface prepared by the standard method in which a mechanically polished surface is oxidized in the atmosphere of reduced pressures.