A New Equation for Predicting the Dielectric Constant of a Mixture

The dielectric constant of a compound consisting of two different materials was simulated using the Monte Carlo and finite element methods. In the high concentration range of the higher dielectric constant material, the simulated value of the dielectric constant showed a "parallel-model"-like tendency. On the other hand, in the low concentration range of the higher dielectric constant material, the compound showed a "serial-model"-like behavior. Around 65% content of the higher dielectric constant material, it exhibited results similar to the logarithmic mixing rule. After careful consideration of these results, a new equation to predict the dielectric constant of the compound was derived. The agreement between the dielectric constant calculated by the new equation and the measured values was better than in any other case reported before.     

Fundamental design and electrical characteristics of superconducting commutatorless motor

Since there are no iron cores in the rotor and stator windings of superconducting synchronous motors, some reactances are intrinsically smaller than those of conventional motors. Thus the low synchronous reactance would be expected to improve the torque-ampere ratio stability and the overload capacity in case of the variable-speed drive system of a load-commutated inverter due to the small armature reaction. Moreover, the low subtransient reactance may contribute to lessen the voltage stress during the shortened commutating period, especially in current source-type inverter (CSI) systems. In this paper, after presenting analytical formulas needed for a machine design, one design algorithm is described, citing one example of an experimental CSI-fed superconducting motor of 30 kVA which will be fabricated. Further, the distinguished features in its operation, as expected in the foregoing, are verified by the computer simulation study in comparison with a conventional machine in terms of a high specific power density, an extension of stable power limit, and so on.     

Oxidation of silicon carbide in a wet atmosphere

The effects of water vapour on oxidation of pressureless-sintered silicon carbide containing alumina as a densifying aid were studied in a wet air flow with 10, 20, 30 and 40vol% H₂O at 1300° C for 100h. The oxidation kinetics were determined in a wet air flow with 20 vol % H₂O and in a dry air flow at 1300° C for times up to 360 h. The weight gain on oxidation showed an increasing tendency with increasing water vapour content. Water vapour in the atmosphere strongly influenced oxidation and accelerated the reaction. Oxidation in a wet atmosphere proceeded in a diffusion-controlled manner, in the same process as that for the dry atmosphere. No remarkable differences were noticed in the microstructure of the oxide layer and the surface roughness between the samples oxidized under the four wet conditions, but the surface roughness increased with increasing oxidation time. Water vapour evidently accelerated the devitrification of amorphous silica and promoted oxidation. Oxidation in a wet atmosphere (10 to 40 vol % H₂O for 100 h and 20 vol % H₂O up to 360 h) had a slight degrading effect on the flexural strength. The microstructure or surface roughness of the oxide layer formed during oxidation presumably had very little effect on the room-temperature strength.     

Velocity Errors of the Resolver Phase Shifter

An equivalent circuit is derived by applying the theory of two-phase symmetrical components to the rotating resolver phase shifter, in which a resistance and a capacitor are connected to the secondary windings of the resolver, and an output voltage equation for calculation of velocity errors is also derived on the basis of this equivalent circuit. Based on the analysis of the output voltage equation, effects of the rotor speed on the magnitude of the output voltage and the phase-angle error are investigated.     

Secondary electron emission from polymers and its application to the flexible channel electron multiplier

The basic characteristics of secondary electron emission (SEE) from various organic compounds have been investigated, and a channel electron multiplier with high gain and flexibility has been developed. The maximum SEE yield is higher for the aliphatic compound than for the aromatic, and is higher for the organic solid with high ionization potential. By studying the SEE yields from the electron-conductive polymeric compositions which consist of plasticized poly(vinyl chloride) and electroconductive particles (NaTCNQ or carbon black), it is shown that the SEE yield depends mainly on the characteristics of the matrix polymer and is almost independent of the addition of electroconductive particles which inherently have low SEE yields. Adding less than 5% stabilizers to these polymeric compositions has little effect on the SEE yields. A flexible channel electron multiplier (FCEM) made of the electron-conductive polymeric composition shows the following characteristics: gain ? 10⁸ (applied voltage of 3 kV); rise time ? a few nanoseconds; background count rate < 0.1 cps; and maximum output current ? 10^?6 A. As a photon detector in the vacuum UV region, the FCEM shows a threshold value of 8.4 eV for photoelectric emission.     

Photoelectrochemical observations on chlorophyll- carotene interactions in a lipid bilayer film

Photoelectrochemical investigations were undertaken on energy transfer and other interactions between chlorophyll-a (Chl-a) and β-carotene (Car) in lipid monolayers. A heterobilayer composed of a Chl-a-lecithin monolayer and a Car- lecithin monolayer was prepared on an SnO₂ semiconductor electrode by Langmuir-Blodgett techniques. When the bilayer-coated electrode was irradiated in an aqueous electrolyte, anodic photocurrents due to the sensitizations by Chl-a and Car respectively were observed. The photocurrent efficiency (ratio of photons to electrons) was much for Car (about 10^-3) than for Chl-a (about 10^-1). This large difference permits a quantitative estimation of the energy transfer from Car to Chl-a, based on the concept that the energy transfer results in an increase in the Car- induced sensitized photocurrent. The effect of added Chl-a on the Car photocurrent was measured for heterobilayers with various Chl-a-to-Car molar ratios. The experimental results, as well as theoretical calculations, showed that the Car-to- Chl-a energy transfer is inefficient. The effect of Car on the Chl-a-sensitized photocurrent was also studied with the same bilayer system. The effect was shown to be complex depending on the Car content. A lowering of the Chl-a photocurrent occurred at high Car contents, which is considered to reflect the quenching of the Chl-a excited triplet by Car. The usefulness of the present photoelectrochemical approach for the study of energy transfer between the photosynthetic pigments is demonstrated.