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Capacitated lot sizing is a frequently encountered production-planning problem in manufacturing companies. However, many real life factors are usually not taken into account during the model development phase for these problems. In this study, an integrated lot-sizing and scheduling problem of a paper bag production firm is considered. A mixed integer mathematical programming model is proposed for modeling and solving the problem. Setup cost/time between product and period changes are considered in the proposed model. It is aimed to minimize the total cost of production, holding inventory, backorder, procurement and setup for product type change and product period change. It is observed that productive utilization of manufacturing resources and the generation of more effective production plans are possible by the application of the proposed model. [ABSTRACT FROM AUTHOR]

Although sufficient amounts of wheat are produced in Turkey, which ranks first in the world in terms of flour export, wheat imports negatively affect the sector. In general, farmers in Turkey produce in small quantities in small production area, and deliver their products with small capacity vehicles and multiple trips. Purchased wheat is classified according to quality characteristics in collection silos, and wheat purchase is limited by harvest period. On the other hand, shipments to the factory from collection silos can be made all year around. In this paper, a 0-1 mixed integer programming formulation for wheat supply network design is proposed to supply sufficient wheat with the desired quality and lowest cost. The proposed formulation uses vehicles with different capacities and reduces the number of trips by choosing the appropriate vehicle for the load amount. In addition to the road, the formulation also considers the rail option. In its current form, the considered problem is described as a wheat supply network design problem with capacity-constraint multi-period multi-stage multi-modal multi-product. The proposed formulation has been tested using real data in a wheat flour factory operating in Konya. The formulation, which was run for three different scenarios of the company, provided sufficient and desired quality wheat by optimizing transportation costs. Computational results recommend the rail transport option in some regions. The results of the formulation are thought to be of a nature that guides the company's tactical and strategic plans. [ABSTRACT FROM AUTHOR]