The could figure of the positive corona discharge in Wilson cloud chamber is a branching' figure, but sometimes a ring or a semi-sphere is seen in the center of the figure. The ring or the semi-sphere cloud figure depends on the sharpnessof the needle and the crest value of the impressed impulse voltage. When the needle is sharp and also the impressed voltage is high, such a cloud figure appears. When the expansion ratio is smaller than the value which is suitable for appearance of the branching figure, or the impulse voltage is sent to the needle sooner a little, the branching figure diffuses, while the ring or the semi-sphere cloud figure appears more clearly. As the reason for appearance of such a cloud figure, the corona wind from the needle is considered. Experiments are carried out in air which contains some water and ethylalcohol vaper, , with a single needle electrode and a double needle electrode.
Number density and size distribution of bubbles formed by cavitation in a rapid flow of liquid through a nozzle into a vessel under reduced pressures are studied in order to clarify the performance of, and also to obtain a sound basis for the design of, a simple deaerator in which such a cavitation is utilized. The way in which the dissolved gas in liquid is liberated by the swarm of bubbles rising in the liquid under reduced pressures, is also investigated experimentally. A simple theoretical consideration is put forward to explain the experimental results. The main conclusions obtained may be summarized as follows: 1) As the pressure in the vessel is reduced, the average size of bubbles formed by cavitation steadily increases while the number density of bubbles increases at first and then, through a maximum at the total pressure between 200 mmHg and 300 mmHg at the nozzle, decreases. 2) There are only small differences in the size and the number density of bubbles when different nozzles are used. The average size of the bubbles varies from 0.4×10-2cm to 1.3×10-2cm in diameter. The number density of bubbles amounts to about 5.0×105/cm3 at the peak. 3) The air concentration in the liquid taken out of the vessel satisfies approximately the following relation. _??_ when the pressure at the nozzle (ha+h0) is larger than about 70mmHg, while, under lower pressures than this value, correction should be made by a factor ƒ.
We have found that the domain structure in annealed state, of a 40 percent cobalt-nickel single crystal is very fine and complicated as compared with that of ordinary ferromagnetic crystals but, after being quenched from above the Curie temperature, it becomes larger and simpler. This can be explained as follows:-Since the domain structure it considered fine and complicated at temperatures just below the Curie point, the domain walls must be displaced to attain a more stable domain configuration at low temperatures. But, this process is suppressed appreciably at relatively low temperatures, because, in solid solutions, uniaxial anisotropy is induced, in compliance with the domain distribution, by anisotropic distribution of atom pairs at high temperatures and the domain wall displacement can take place only when accompanied by redistribution of atom pairs which can not occur at low temperatures. In quenching, the specimen is cooled down so rapidly that the uniaxial anisotropy and hence the anisotropic distribution of atom pairs can not be induced and thus the quenched specimen behaves just as ordinary ferromagnetics. It is shown that these findings together with the results of considerations reported previously lead us to the conclusion that the perminvartype magnetic properties are due to the stabilization of domain walls by the induced uniaxial anisotropy in f. c. c. solid solutions and in b. c. c. solid solutions with negative cubic anisotropy constants.
Design of “photo-tracer”, an apparatus for measuring photoelastic fringe order by means of photoelectric method, is described. The apparatus is being used not only to measure the fringe order of isochromatic lines, but also to determine the darkest position of isoclinic lines. The apparatus enables the fringe order to be determined with the accuracy of 1/1000 of the fringe width.
An improved method of anodic oxidation for titanium is described. The process consists of two stages, anodization with lower current densities of less than 0.5 mA/cm2 for about half an hour and subsequently with higher current densities of more than 5 mA/cm2. Compact oxide films are formed on the surface of titanium plates anodically. It is difficult to produce dense oxide films on the surface of titanium by the ordinary electrolytic anodization method which is commonly used for aluminium by applying high current densities of more than 5 mA/cm2 from the begining. The oxidized film produced at the early stage of this ordinary method is TiO2 (Anatase). During the first stage of the improved method, on the contrary, fine oxidized film is formed growing denser with time and found to be amorphous by electron diffraction. The amorphous film turns into TiO2 (Anatase) by successive anodization. The electron microscope and diffraction studies indicate that the formation of oxide film at the early stage of anodization is essential to obtain suitable dense oxide film in the application of titanium to electrolytic condesner.
Pieces of α-brass (Cu 70, Zn 30) wire of l mm in diameter are cold-worked to various degrees by rolling and twisting, and annealed at a constant rising rate of 1.7°C/min from the room temperature to 4600°C. The rigidity is measured by means of a torsion pendulum at various temperatures during the annealing. (1) The rigidity of annealed specimen decreases slowly in a linear manner with rising temperature up to about 240°C, and departs rapidly from this linear relation at this temperaJture. (2) There is a marked difference in the aspect of the temperature change of rigidity :according to either the specimens are cold-rolled or cold-twisted. In cold-twisted specimens the rigidity recovers rapidly at first up to about 60°C, but in cold-rolled specimens this is not observed. In cold-twisted specimens the rigidity increases gradually from this temperature, up to a certain temperature θ1, but as the temperature rises higher than this value, the rigidity becomes almost constant up to a certain temperature θ2. On the other hand, in cold-rolled specimens the rigidity increases gradually from the beginning of measurement up to θ1 and within the temperature range of θ1 and θ2 the rigidity increases at a moderate rate with rising temperature. In either case, the rigidity begins to increase at the temperature θ2 at which the recrystallization begins. (3) For all specimens tested, the rigidity decreases at first and reaches a minimum, after which it increases gradually as the degree of cold-working steadily advances. But the mode of change is different for cold-rolled and cold-twisted specimens. (4) The change of the rigidity caused by cold-working may be explained as the combined, effect of three factors, that are, lattice distortion and rotation of crystal grains, both of which make the rigidity decrease, as well as the fragmentation of the grains which increases the rigidity.
Parts of the living body that are perceptible to vibrations tangible to the tips of fingers have been observed over a range from 10 to 500 cps with a vertical vibration generator. Between the finger tips and the elbow, there are parts, each of which perceives characteristic frequencies resonant to it as shown below which are observed on the writer's own body. Elbow 10_??_20 cps; Wrist joint 30_??_50 cps; Palm 60_??_80 cps Metacarps phalangeal joint of middle finger 90_??_100 cps Proximal phalanx joint of middle finger 150_??_200 cps Interphalangeal joint joint of middle finger 200_??_250 cps Middle phalanx joint of middle finger 300 cps Distal interphalangeal joint joint of middle finger 350 cps Distal phalanx joint of middle finger 400 cps
In nuclear research, pulse amplifiers with short rise time in millimicrosecond regions are now requiered for scintillation counters. A high gain, wide-band distributed amplifier has been made for the purpose. This amplifier, consisting of only four tubes of secondary emission type, EFP-60, has a gain of 70 in the frequency region from 500 c/s to 100mc/s and its rise time is below 10 millimicroseconds, and the obtained output pulse voltage is over 100 volts. Amplifiers of this type are suitable for high speed synchroscope units because the push-pull output voltages are obtained directry from the anode-dynode constructions.
Measurement of diffusion constant by means of three-slits interferometer is des cribed. By changing the second refractive index, the diffusion constant is calculated using polyvinylalcohol in aqua between two plan parallel plates.