Publications

Oxygen reduction in a gas‐fed porous electrode attached to a proton exchange membrane is discussed. Experimental data and a mathematical model are presented for the test cell used. Various membrane and electrode assemblies were tested at different levels of platinum loading and Teflon® content. The model accounts for the diffusion and reaction of oxygen and the diffusion and reaction of hydrogen ions. Sulfuric acid was placed above the membrane in the test cell reservoir to provide a source of protons for the reduction of oxygen at the cathode. Based upon model predictions, it is shown that the transport of the protons in the active layer of the cathode is an important factor in the operation of the test cell.

An algebraic model for a parallel plate, zinc/bromine flow cell is presented and used to predict various performance quantities, which are compared to those predicted by using previously published differential equation models. The results presented compare well with previous work. The model is based on the concept of using well‐mixed zones and linear concentration and potential profiles for the diffusion layers and the separator. The Butler‐Volmer equation is used for the electrochemical reactions, and the homogeneous reaction between bromine and bromide is included.

A one-dimensional mathematical model for the lithium/thionyl chloride primary cell is used in conjunction with a parameter estimation technique, in order to estimate the electrode kinetic parameters of this electrochemical system. The electrode kinetic parameters include the anodic transfer coefficient and exchange current density of the lithium oxidation, $\alpha$a, 1 and io, 1, ref; the cathodic transfer coefficient and the effective exchange current density of the thionyl chloride reduction, $\alpha$c, 4 and a°i0, 4, ref, and a morphology parameter, $\xi$. The parameter estimation is performed on simulated data first in order to gain confidence in the method. Data reported in the literature for a high-rate discharge of an experimental lithium/thionyl chloride cell is used for an analysis. © 1989, The Electrochemical Society, Inc. All rights reserved.

A two-dimensional thermal model for spirally wound batteries has been developed. The governing equation of the model is the energy balance. Convective and insulated boundary conditions are used, and the equations are solved using a finite element code called TOPAZ2D. The finite element mesh is generated using a preprocessor to TOPAZ2D called MAZE. The model is used to estimate temperature profiles within a spirally wound D-size cell. The model is applied to the lithium/thionyl chloride cell because of the thermal management problems that this cell exhibits. Simplified one-dimensional models are presented that can be used to predict best and worst temperature profiles. The two-dimensional model is used to predict the regions of maximum temperature within the spirally wound cell. Normal discharge as well as thermal runaway conditions are investigated.

Amorphous alloys also known as metallic glasses appear to have unique corrosion resistant properties. The corrosion characteristics of a (Ti90Ru10)87Si13 alloy have been measured in 0.5 M NaCl and in artificial seawater (ASW) by linear polarization resistance, ac impedance and small amplitude cyclic voltammetry (SACV). Results show a low corrosion rate of the alloy in these media, with the rate of corrosion in seawater slightly faster than the rate of corrosion in sodium chloride. © 1989.

English to Indian language machine translation poses the challenge of structural and morphological divergence. This paper describes English to Indian language statistical machine translation using pre-ordering and suffix separation. The pre-ordering uses rules to transfer the structure of the source sentences prior to training and translation. This syntactic restructuring helps statistical machine translation to tackle the structural divergence and hence better translation quality. The suffix separation is used to tackle the morphological divergence between English and highly agglutinative Indian languages. We demonstrate that the use of pre-ordering and suffix separation helps in improving the quality of English to Indian Language machine translation.

Polypyrrole is an attractive polymer for use as a high-energy-density secondary battery because of its potential as an inexpensive, lightweight, and noncorrosive electrode material. A mathematical model to simulate cyclic voltammograms for polypyrrole is presented. The model is for a conductive porous electrode film on a rotating disk electrode (RDE) and is used to predict the spatial and time dependence of concentration, overpotential, and stored charge profiles within a polypyrrole film. The model includes both faradic and capacitance charge components in the total current density expression.