Lot sizing model for multiple products over finite planning horizon under the effect of learning and time-value of money with cap-and-trade and carbon tax regulations: a fuzzy framework

This study presents a multi-item manufacturing process by assuming that the demand for different products depends on the selling price and awareness program. The manufacturer adopts a system improvement program to reduce the defective items and an investment policy on green technology to curb carbon emission. This article also explores the influence of learning on unit production time. Impreciseness in different costs is handled with fuzzy set theory. The optimal solution is obtained with the help of the classical optimisation technique. Further, obtained results indicate the advantage of carbon regulation policies as carbon tax and carbon cap and trade policy. The result also shows a significant improvement in the system's profit by considering the learning effect. The whole of the study is carried out under the impact of inflation. The developed model is investigated further with the help of a numerical example. In the end, sensitivity analysis is performed for important parameters.