Two-period production planning and inventory control

We study a single product two-period production/inventory model, in which the demands at each period are independent random variables. To optimally satisfy these random demands, quantities can be produced at the beginning of each period using slow or fast production mode, under capacity constraints. In addition to the usual decision variables for such models, we consider that a certain quantity can be salvaged at the beginning of each period. Such salvage processes are useful if the initial inventory of a period is considered to be too high. The unsatisfied demands for each period are backlogged to be satisfied during the next periods. After the end of the second period, a last quantity is produced in order to satisfy remaining orders and to avoid lost sales. The remaining inventory, if any, is salvaged. We formulate this model using a dynamic programming approach. We prove the concavity of the global objective function and we establish the closed-form expression of the second period optimal policy. Then, via a numerical solution approach, we solve the first period problem and exhibit the structure of the corresponding optimal policy. We provide insights, via numerical examples, that characterize the basic properties of our model and the effect of some significant parameters such as costs, demand variabilities or capacity constraints

Supplementary Materials for: "Sustainable multi-vehicle traveling purchaser problem with speed optimization and social cost of CO2"

Supplementary material #1: Data files of 24 MVTPP instances as MATLAB files used to validate the proposed heuristic in the article: "Sustainable multi-vehicle traveling purchaser problem with speed optimization and social cost of CO2".Supplementary material #2: Data files of 81 MVTPP instances as MATLAB files used to study the complexity of the problem investigated in the article: "Sustainable multi-vehicle traveling purchaser problem with speed optimization and social cost of CO2".THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Best Maritime Transportation Option for the Arctic Crude Oil: A Profit Decision Model

Navigation via the Northern Sea Route (NSR) requires specific vessels in comparison with the Suez Canal Route (SCR). We develop a profit decision model that defines the best option mixing the shipping lane (NSR or SCR) and the ice-class of the vessel (1A, 1AS, and Open Water (OW)) for oil producers operating in the Russian Arctic zone. The effects of the Brent barrel price, bunker cost and ice-thickness are analyzed. The best option depends in fact on the strategy implemented by the shipper. For instance, the solutions of a profit focused strategy or of a cost-oriented strategy are different. © 2020 Elsevier Lt

The feasibility of Arctic container shipping: the economic and environmental impacts of ice thickness

An evaluation of the competitiveness of the Northern Sea Route (NSR) for container shipping services, considering ice thickness changes during the year, is presented in the present work. The variation in ice thickness has three implications. Firstly, it entails a probability of blockage in ice and reduces the number of days in which a round-trip liner service can be completed. Secondly, ice thickness impacts schedule integrity. Thirdly, it impacts costs (icebreaker fees and fuel consumption), transit time, and the amount of CO2 emitted per TEU. Accounting for these elements in a model and then in a business case, this study concludes that NSR liner services are only competitive, compared with the Suez Canal Route or the Trans-Siberian Railway Connection, for a limited period of 1.5 months per year