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Ornge provides air-ambulance services to the province of Ontario. A major part of its services involves prescheduled transports between medical facilities. These transports almost exclusively require fixed-wing aircraft because of [...]

In this paper, we consider two fundamental inventory models, the single-period newsvendor problem and its multiperiod extension, but under the assumption that the explicit demand distributions are not known and [...]

We consider two classical stochastic inventory control models, the periodic-review stochastic inventory, control problem and the stochastic lot-sizing problem. The goal is to coordinate a sequence of orders of a [...]

We consider several classical models in deterministic inventory theory: the single-item lot-sizing problem, the joint replenishment problem, and the multistage assembly problem. These inventory models have been studied extensively, and [...]

A study aimed at minimizing the weighted sum of the job completion times has developed two techniques for the design of approximation algorithms for NP-hard scheduling problems. The techniques produced the first constant performance guarantees for different scheduling models. The first approach used an optimal solution to a linear programming relaxation to handle a simple list-scheduling rule.

Several algorithms for the rapid solving of fractional packing and covering problems are introduced. The algorithms, which use the Lagrangian relaxation technique, are based on an extension to a method for deriving approximate solutions for multicommodity flow problems. They may be applied to job shop scheduling, the Held-Karp bound for the traveling salesman problem, network embedding problems and the minimum-cost multicommodity flow problem.