The speaker of condenser type has an advantage over the speaker of moving coil type in high frequency region of acoustic waves, for in the former the driving force acts directly upon the whole of the vibrating diaphragm and the diaphragm can be made very light, less than a milligram per cm2. But for obtaining the response in medium and low frequency regions as high as in high frequency region, use of a large diaphragm, high direct bias voltage and high signal voltage becomes necessary, which is not practical. Condenser type speakers with diaphragm made of ribbon-shaped vibrating units have been made. Because of a large electric capacity of the speaker and a large effective area of the diaphragm, the speaker can be driven by a direct bias voltage of 300400 volts and a signal voltage of 50_??_60 volts. Of these speakers, electric capacity, dumper and driving force are described and several frequency-response characteristics obtained experimentally are shown. These speakers have a nearly constant response over the range of 500-12000 c. p. s.
Friction between a flat plate of plastic and two hard hemispheres of different radii of curvature is studied. Hertz's equation can be applied to the contacts between the plate and the hemispheres. With the glass hemisphere, about 4 cm in radius, the frictional force is verified to be proportional to the contact area. The proportional constant is closely related to Young's modulus of plastic. With the steel hemisphere, 0.24cm in radius, a grooved track is formed on the plastic after rubbing, and the frictional force is found not proportional to the contact area. However, this is not the behaviour that can be explained by the effect of ploughing force. It is found that the formation of track is mainly originated from a non-recoverable part of deformation under the compression by the hemisphere. If Young's modulus in the equation is assumed to depend upon the sliding speed of hemisphere, Hertz's equation seems to become applicable to the track width. It is concluded that the friction on plastics is likely to be caused by the resistance to surface deformation.
A number of triglycerides are fractionated from butter by decanting it with methyl ethyl keton solution at elevated temperatures. The fractionated triglycerides are crystalized from the solution with various solvents and by the use of low temperature replica method the crystals are morphologically examined by electron microscope. The crystal growth is found to vary by the kind of solvent; generally the crystals assume a needle-like form. A triglyceride of m. p. 55°C had the height of the growth step of approximately 500 Å which is roughly ten times of the longest chain of triglyceride molecules suggesting that the step is of multiple layer of molecules. Such growth can conveniently be explained by the kinematic wave theory.
A negative hydrogen ion source which yielded a maximum current of 1.6pA of H ions has been built. This is accomplished by first producing approximately 500μA of positive ions in a RFtype ion source. These ions are extracted and their charge is exchanged in an electron pickup tube of convertor, which serves as an extracting electrode. These negative ions are further accelerated up to 20 KeV and are focused on a 3 mm diameter spot by an electrostatic saddle field lens and then are magnetically analyzed.
For the purpose of reading the beam current, use of an ionization chamber attached directly to the beam scanner of a Van de Graaff generator is examined. It is shown that, when the beam current is large, saturation current is difficult to be obtained even the voltage is raised high, but in the range of low voltage, the relation of ionization current to applied voltage is linear. From this linearity, the beam current can easily be determined. This method has the advantage of measuring or controlling the beam current while the irradiation is being carried on.
In the first part of the present paper the structure of the accelerating tube and some important techniques in its construction such as conductive coating of the inner surface and the assemblage of electron gun are described in some detail. In the second part, some problems connected with the auxiliary circuits for the betatron such as electron-injection circuit, orbit expanding circuit and monitoring circuit are discussed. Lastly, the controlling system and the operation of the betatron are described.
It often happens that partially overlapped two lines on photograms, when viewed with the naked eye, appear distinctly separated by a region of minimum density, but when measured microphotometrically, the obtained curve has no minimum. The illusion of this kind which gives rise to errors is explained by demonstrating it on photographs of made-up double line taken by light of given intensity distribution.
To enable two or more signals of very different intensities or signals with occasional high peak of intensity to be recorded on one and the same recording sheet without altering the sensitivity of the recorder, a device is made in which the moving direction of recording pen is automatically reversed at the end of the indicator scale backward toward zero of the scale, and with further rise of intensity it is reversed again at zero toward the end of the scale. This reversal of direction occurs also during falling of the intensity. In this way, strong signals are recorded on the recorder which is made sensitive to weak signals much more effectively than the double pen system which only doubles the range. This device can be used for recorders of constant as well as varying reference voltage. The reversal of direction is effected by reversing the polarity of slide wire, by reversing A. C. input or signal input to servo motor and by changing the position of slide wire in reference voltage network. The device is composed of a signal generator, a polarity reversing unit and a range changing unit with relays and switches. Operation of the device is explained and recorded results are shown.
Electrification by being forced through the air of sprayed skim-milk, powdered skim-milk and other foodstuff-powdered whole-milk, powdered butter-milk, powdered lactose and flour-is measured by the gain of potential in their swift movement. In spraying of skim-milk, charge on most of the particles atomized to about 200μ in diameter is positive while that on larger ones is negative. In pneumatic conveying of powdered skim-milk through duct, amount of positive charge on particles incleases with their concentration in air and the velocity of air stream. Concerning those foodstuff that were examined, amount of charge on powder particles of less than about 25μ in diameter increases with their surface area, but for larger particles, it is the volume rather than the surface that determines the increase. Powder particles except those of lactose are almost charged positive if they are small, but negative if large. Particles larger than about 80μ in diameter have no polarity. Charge per particle ranged 0.394×10-4-_??_4.142×10-4 e. s. u., and mean density of charge 0.881.85 e. s. u. /cm2.