Abstract

The results of theoretical and experimental investigations of the special synchronous machine and the electrical drive on its base are submitted. This paper covers the principle of operation the brushless synchronous machine, its experimental characteristics, comparison with other types of motors, technique of account of the electromagnetic torque, functional circuits of the electric drive with the independent excited synchronous reactive motor (FRRM - Field Regulated Reluctance Machine). It is the most favorable application of the considered electric drive in the vehicles with heavy conditions of operation, where such are urgent it advantages, as: brushless, high rigidity of the shaft, large overloads on the torque. It can be used in the regular cars for starter generators, in pure-electrical and hybrid-electrical vehicles for power drive, in independent power generating installations with high-speed of the gas turbine engine and so on. Copyright © 2007 SAE International.

Abstract

The acid dissociation constants (pKas) of perfluoroalkyl carboxylic acids (PFCAs) have been the subject of discussion in the literature; for example, values from -0.2 to 3.8 have been suggested for perfluorooctanoic acid (PFOA). The dissociated anionic conjugate bases of PFCAs have negligible air-water partition coefficients (KAWs) and do not volatilize from water. The neutral acids, however, have relatively high KAWs and volatilization from water has been demonstrated. The extent of volatilization of PFCAs in the environment will depend on the water pH and their pKa. Knowledge of the pKas of PFCAs is therefore vital for understanding their environmental transport and fate. We investigated the water-to-air transfer of PFCAs in a novel experimental setup. We used ∼1 μg L(-1) of PFCAs in water (above environmental background concentrations but below the concentration at which self-association occurs) at different water pH (pH 0.3 to pH 6.9) and sampled the PFCAs volatilized from water during a 2-day experiment. Our results suggest that the pKas of C4-11 PFCAs are "1.6. For PFOA, we derived a pKa of 0.5 from fitting the experimental measurements with a volatilization model. Perfluoroalkane sulfonic acids were not volatilized, suggesting that their pKas are below the investigated pH range (pKa "0.3).