Recent developments in electrical properties of amorphous semiconductors have been reviewed. Some experiments on DC and AC conductivities, high-field effect, magnetbresistance, ESR and carrier transport through the junction are given. New models and interpretation for them are introduced. A few methods for the evaluation of Mott's parameters are also discussed.
Waveforms of an ArII laser excited by the discharge of a square current pulse have been observed. The onset of laser oscillations is delayed by τD relative to the start of the current pulse; τD decreases with increasing discharge current. These results can be explained by solving the rate equations for a simplified four-level model in which radiation trapping and the variation of ion temperature at the initial stage of discharge are considered. Changes of waveform with the discharge current is also explained on the basis of the difference in the excitation mechanism for upper levels and that for lower levels.
There are two ingeneous methods of recording computer-generated Fourier transform holograms: namely Lohmann's binary holograms and Lee's sampled Fourier transform holograms. In this paper, we point out that holograms generated by these two methods are interpreted as differently sampled ones referring to the optical set up in the identical geometry. A generalized equation of transmittance of computer-generated Fourier transform hologram is derived by a way of this geometry, The generalized equation includes these two types of holograms. Moreover, improved images are reconstructed from holograms generated by new methods, which are derived from the generalized equation. Experiments are done, where line printer displayed holograms are used and some conclusions are reached.
The movable tube gas flowmeter of angular momentum type already reported indicates that the theoretically calculated values of the mass flow rate of a gaseous substance agree fairly well with the experimentally measured values. The gas flowmeter reported in this paper is a movable L tube flowmeter of momentum type with a thermometer and manometer. This flowmeter enables us to find the mass flow rate of a gaseous substance by measuring the force acted on the movable tube, the temperature and pressure at the inlet (or outlet) section of the tube. The theory of the flowmeter is based on the assumption that the velocity is uniform all over the inlet (or outlet) section. When this assumption does not hold a discharge coefficient is needed to correct the small error due to lack of uniformity of velocity. The experimental results show that the discharge coefficient for a gas is equal to that for a liquid provided they have the same Reynolds number. The discharge coefficient for air determined experimentally is 0.98 in the region of Reynolds number 1×104_??_3.3×104.
New curious image-forming action was found experimentally for the Moiré pattern by holding the spacing-gap between two fly's-eye lens plates at a well-adjusted value. The Moire pattern, consisting of many disk-like patterns, can act as many imaging lenses capable of varying the image size and controlling the direction of image in an extremely simple way, i.e. changing the rotation angle of the plates. Through detailed investigations including the analysis of Moiré lens, it has been clarified that many pairs of two micro-lenses whose focal planes coincide approximately and whose centers displace slightly each other play an important role in this phenomenon.
An injecting water dew point hygrometer using atmospheric pressure as the standard of the pressure difference measurement is described. A sample gas is introduced into a metal vessel which is connected to two U-tube mano-meters, one of which has one end open to the atmosphere and the other attached to a pump for changing the volume of the sample gas. As water of constant volume is injected into the vessel, the pressure of the sample gas increases, and when the pressure is reduced to the initial pressure, the volume of the sample gas will be increased. The dew point of the sample gas is determined theoretically either from the increased pressure before and after the injection of water or from the increased volume after the reduc-tion of pressure; in both cases the temperature of the sample gas is made the same before and after the injection. It is shown experimentally that both the constant volume and the constant pressure methods are applicable for measuring the dew point with a high accuracy.