A REGIONAL CONVEXITY TEST FOR GLOBAL OPTIMIZATION - APPLICATION TO THE PHASE-EQUILIBRIUM PROBLEM

This paper introduces a new method for testing the convexity of a func tion in an n-rectangular region of its domain which may be used in con junction with a branch and bound global optimization algorithm to impr ove its convergence rate. The method makes use of interval analysis te chniques together with a determinant test based on Schur complements. Its enhancement of a global optimization algorithm is demonstrated on a set of phase equilibrium problems which are formulated as nonconvex Gibbs energy minimization problems where the Gibbs energy function is modelled using the NRTL equation. (C) 1998 Elsevier Science Ltd. All r ights reserved.