Alternating current impedance studies on oxide films in metal/oxide/electrolyte systems: a modified approach

The accurate determination of the impedance of oxide films in metal/oxide/electrolyte systems is shown to be possible through a modified procedure. The film impedance thus determined is found to be quite different from the measured cell impedance for anodic aluminium oxide formed on pure aluminium. The computed values of tan and conductivity are found to be in agreement with the values reported earlier for anodic and thermal oxides.     

Dissociation constants of long chain fatty acids in methanol-water and ethanol-water mixtures

The pK_a values of lauric acid, myristic acid, palmitic acid and stearic acid in methanol-water and ethanol-water mixtures of different compositions at 303 K and ionic strength, I=0.1M(KNO₃) have been determined. The pK_a values of the fatty acids have been found to increase with the alcohol content of the solvent. It has also been found that, in general, the pK_a values in the ethanolic solvent are greater than those in the methanolic solvent. In a given solvent mixture the observed pK_a value decreases in the order of stearic acid > palmitic acid > myristic acid > lauric acid. Departure from the predicted linearity of the plots of pK_a against the inverse of the dielectric constant, 1/D indicates that the electrostatic effects taken into account by the Born theory are not adequate enough to represent the total medium effects on pK_a.     

Technology trends in microcomputer control of electrical machines

A comprehensive review of technology trends in microcomputer control of electrical machines is presented. Although microcomputer control and computer-aided design techniques are the main themes of discussion, motion control as multidisciplinary technology has been reviewed in the broad perspective of electrical machines, power semiconductor devices, converter technology, microcomputers, and VLSI circuits. The concepts discussed are valid not only for small machines, but for large machines as well     

CdTe photoelectrochemical solar cells—chemical modification of surfaces

Chemical modification of bothn andp type CdTe has been found to improve the performance and stability of PEC solar cells. The surfaces, modified by Ru³⁺, have been examined by a variety of techniques. Modification results in enhanced barrier height at the surface due to the formation of a passivating oxide layer.     

A State Language for the Sequencing in a Hybrid Electric Vehicle

The application of a state language to the real-time control of a hybrid electric vehicle is explained. The state language has been developed both as a specification aid to the system designer and as a means for the programmer to produce microcomputer software. A translator program, which was developed on a VAX minicomputer, preprocesses the state language into a software module to be compiled by the standard Intel PL/M 86 compiler.     

Direct electrowinning of lead from galena concentrate anodes

The results of an investigation of the electrowinning of lead directly from a galena concentrate compact anode employing an acetate bath as the electrolyte are reported. The effects of graphite content in the compact electrode, bath composition, time of electrolysis, temperature of the bath, current density and compaction pressure were studied on a laboratory scale to optimize operating conditions. An electrode containing 6.25% graphite, compacted at 238 MN m^?2 for 5 min, resulted in 70% current efficiency for the dissolution of lead according to the reaction PbS → Pb²⁺ S⁰ + 2e in a bath of ammonium acetate (0.5 M), acetic acid (0.35 M) and lead acetate (0.1 M) when electrolysed at 333 K with a current density of 110.5 A m^?2. The results have formed the basis of a pilot plant design.     

Generalized inverse of polynomial matrices

Investigations are made into conditions that preserve the algebraic structure of a matrix in its generalized inverse, with particular reference to polynomial matrices. The procedure also constructs such a type of inverse, when it is found to exist.