l. e. cardenas barron

Many applications of optimisation require the final value of the decision variables tobe integer. In many cases the relaxed optimal solution does not satisfy the integral-ity constraint therefore, the problem must be solved by integer or mix-integer pro-gramming algorithms at a significant computational effort and most likely a worsenobjective function value. The contribution of this paper is twofold: The identificationof a type of problems in which the relaxed optimal objective function value can bekept in the implementation by a change in the planning horizon; and the identifica-tion of a multi-period based solution procedure. Three small instances are providedin order to illustrate the methodology as well as the economic impact involved. Inaddition, a fourth industrial size case is included for the benefit of practitioners.This work shows that business profit can be increased for pseudo-continuous-integerperiodical linear problems by identifying optimal decision-making periods.

This research paper builds a manufacturer-retailer integrated inventory model to compute jointly the optimal values for the order quantity, the lead time, the reorder point and the number of shipments taking into consideration the effect of learning-forgetting phenomenon on the setup cost. The fabrication process of manufacturer is not perfect and certain level of product quality can attain with an additional cost. Service level constraint is incorporated into the inventory model to evade the backorder which gives negative impact to company reputation. The lead time is reduced with the help of crashing cost. The proposed inventory model is illustrated with the help of an example. From this example, it is detected that centralized decision is better than decentralized one. It is also observed from the analysis that players have to compromise with their profit if they decide to increment the service level and quality of the product. Due to the effect of learning-forgetting on the setup cost, profit of the centralized system increases.

This study deals with a dual channel supply chain where selling price of each player, delivery time for direct channel and retail service dependent demand structures are considered for manufacturer and retailer. In the direct channel, the manufacturer sells the products directly to the customers with a maximum mentioned delivery time. The delivery time of the products is adjustable according to customers’ demand with extra delivery charge. In the retail channel, the customers are extra benefited by the retail service and direct connection with the products. Selling price for direct market is considered as lower than the retail market selling price. The behavior of the model under integrated system is analyzed. In the decentralized structure, vertical Nash and manufacturer Stackelberg models are also discussed. The sensitivity of the key parameters is examined to test feasibility of the model. Finally, a numerical example with graphical illustrations is provided to investigate the proposed model.

Services are increasingly important in the modern economy, for both service and manufacturing firms, yet inventory literature has been focused mainly on physical goods and, only a few studies have included services in optimization. On the other side, traditional service management literature relies on an extremely narrow definition of inventory that excludes services, because they are perishable. Thus, there is a lack of research in the link between inventory optimization and service management. However, according to a new service inventory approach, businesses components such as tasks or information, as different from physical goods, can be performed and stored in anticipation of service demand as a form of service inventory—that is, inventorying by anticipation rather than delaying the service. This article aims to contribute to this lack of research by proposing a service inventory optimization model that integrates a service orientation to optimize tasks and information to be performed in advance. In contrast with traditional inventory models, where the objective is to optimize physical items, in this approach physical products whenever included, constitute only mechanisms for service provision. This service inventory model contributes to optimize the quantity of tasks or information to be anticipated and thus provides benefits for customers.