The coordinated multi-item inventory problem refers to the problem of managing inventories where there is a joint fixed cost for replenishing plus an item-by-item fixed cost for each item included in the replenishment order. Given that the optimal solution is likely to be too complex, attention has focused on fixed heuristics, and in particular ‘can-order’ or (s, c, S) policies. This paper makes two contributions. First, a new lower bound on the cost of the optimal policy is proposed in order that the performance of heuristics may be measured. Second, motivated by the lower bound, a simple periodic policy is proposed and shown to be an improvement over ‘can-order’ policies for many data sets.

No abstract

A zero-one integer linear programming model is proposed for selecting and scheduling an optimal project portfolio, based on the organization's objectives, and constraints such as resource limitations and interdependence among projects. The major contribution of the paper is that the proposed model not only suggests projects that should be incorporated in the optimal portfolio, but it also determines the starting period for each project. Scheduling considerations can have a major impact on the combination of projects that can be incorporated in the portfolio, and may all ow the addition of certain projects to the portfolio that could not have been selected otherwise. Moreover, the model handles situations that frequently happen in real world applications, in which the amount of available and consumed resources varies in different periods. An example problem is described and solved with the proposed model to ill ustrate the approach, and some areas for future research are discussed .

No abstract

No abstract