Some basic considerations on the Mansfeld method

The mathematical developments of the original and new versions of the Mansfeld method are given and the characteristic function G(u(0)) is introduced. The reliability and effectiveness of the use of G(u(0)) have been verified by processing theoretical data, computed over the Delta E interval [-150. 150] mV at 10 mV steps and describing ideal systems with rather different values of I-c, where B-a does not exhibit large changes and B-c ranges from 70 to 120 mV. The roots of G(u(0)) were computed using a false position method and single precision. Data processing after 30 iterations provided very accurate values of the electrochemical parameters. It was also verified that the accuracy of the improved method does not depend on the Delta E interval amplitude. The convergence criteria of the numerical sequence u(0n-1) + Delta u(n) have been discussed and some applications have been given. The results indicate that the convergence of u(0n-1) + Delta u(n) is very fast and very accurate evaluations of B-a, B-c and I-c are attained after a few iterations. (C) 1998 Elsevier Science Ltd. All rights reserved.