  We propose new mathematical models of inventory management in a reverse
logistics system. The proposed models extend the model introduced by Nahmias
and Rivera with the assumption that the demand for newly produced and repaired
(remanufacturing) items are not the same. We derive two mathematical models and
formulate unconstrained and constrained optimization problems to optimize the
holding cost. We also introduce the solution procedures of the proposed
problems. The exactness of the proposed solutions has been tested by numerical
experiments. Nowadays, it is an essential commitment for industries to reduce
greenhouse gas (GHG) emissions as well as energy consumption during the
production and remanufacturing processes. This paper also extends along this
line of research, and therewith develops a three-objective mathematical model
and provides an algorithm to obtain the Pareto solution.
