Abstract

Abstract

Abstract
This paper analyses distinct methods to represent a polygon through circle covering, which satisfy specific requirements, that impact primarily the feasibility and the quality of the layout of final solution. The trade-off between the quality of the polygonal representation and its derived number of circles is also discussed, showing the impact on the resolution of the problem, in terms of computational efficiency. The approach used to tackle the Nesting problem in strip packing uses a Non-Linear Programming model. Addressing these problems allows to tackle real world problems with continuous rotations. © IFAC.

Abstract

Abstract
Unicer, a major Portuguese beverage company, improved its tactical distribution planning decisions and study alternative scenarios for its supply strategies and network configuration as result of an operations research (OR)-driven process. In this paper, we present the decision support system responsible for this new methodology. At the core of this system is a mathematical programming-based heuristic that includes decision variables that address transportation and inventory management problems. Unicer runs a set of production and distribution platforms with various characteristics to fulfill customers demand. The main challenge of our work was to develop a tactical distribution plan, which Unicer calls an annual distribution budget, as realistically as possible without jeopardizing the nature of the strategic and tactical tool. The company had a complex tactical distribution planning problem because of the increasing variety of its stock-keeping units and its need for a flexible distribution network to satisfy its customers, who demand a very fragmented set of products. Atypical flows of finished products from Unicer's distribution centers to its production platforms are a major cause of this complexity, which yields an intricate supply chain. The quality of the solutions we provided and the implementation of a user-friendly interface and editable inputs and outputs for our decision support system motivated company practitioners to use it. Unicer saves approximately two million euros annually and provides better information to its decision makers. As a result, these decision makers now view their operations from a more OR-based perspective.

Abstract
This work addresses an integrated framework for deciding about the supplier selection in processed food supply chains that accounts for tactical production and distribution planning. We are especially concerned with the option of producing with local or mainstream raw materials. The contribution of this paper is two-fold. Firstly, it proposes a new multi-objective two-stage stochastic mixed-integer programming model for the supplier selection that maximizes the profit and minimizes the risk of a low customer service. Secondly, the main complexities of processed food supply chains management are considered: perishability of raw materials and final products, uncertainty at downstream and upstream parameters, and customer willingness to pay. Results indicate that dual sourcing is a strategy to be pursued across several scenarios. The multi-objective approach shows that a small decrease in the expected value of profit results in a significant increase in the customer service. Acknowledging the increase in customers willing to pay for local products is also fundamental.