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In this study, a comprehensive model for an industrial low-density polyethylene (LDPE) tubular reactor is presented. The model parameters are tuned using industrial data on the temperature profile, the monomer conversion and the number-average molecular weight at the end of the reactor, and estimates of the several side products from the reactor. Complete details of the model are provided. Thereafter, a two-objective optimization of this LDPE reactor is performed; the monomer conversion is maximized while the sum of the normalized concentrations of the three important side products (methyl, vinyl, and vinylidene groups) is minimized. Three variants of the binary-coded non-dominated sorting genetic algorithmnamely, NSGA-II, NSGA-II-JG, and NSGA-II-aJGare used to solve the optimization problem. The decision variables used for optimization include the following:  the feed flow rates of the three initiators …