Optimal retrofit design for improving process flexibility in nonlinear systems. Efstratios N. Pistikopoulos Ignacio E. Grossmann Carnegie Mellon University.Engineering Design Research Center. 10.1184/R1/6467276.v1 https://kilthub.cmu.edu/articles/journal_contribution/Optimal_retrofit_design_for_improving_process_flexibility_in_nonlinear_systems_/6467276 Technical Report 1988-01-01 00:00:00 Flow charts. Nonlinear programming.