This paper is focusing on an important transportation application encountered in supply chains, namely the capacitated two-stage fixed-charge transportation problem. For solving this complex optimization problem we described a novel hybrid heuristic approach obtained by combining a genetic algorithm based on a hash table coding of the individuals with a powerful local search procedure. The prop...

C often face nonstationary demand due to product life cycles and seasonality, and nonstationary demand complicates supply chain managers’ inventory decisions. This paper proposes a simple heuristic for determining stocking levels in a serial inventory system. Unlike the exact optimization algorithm, the heuristic generates a near-optimal solution by solving a series of independent single-stage ...

This paper addresses a class of two-stage robust optimization models with integer adversarial variables. We discuss the importance of this class of problems in modeling two-stage robust resource planning problems where some tasks have uncertain arrival times and duration periods. We apply Dantzig-Wolfe decomposition to exploit the structure of these models and show that the original problem red...

Heuristic concentration (HC) is a two-stage metaheuristic that can be applied to a wide variety of combinatorial problems. It is particularly suited to location problems in which the number of facilities is given in advance. In such settings, the ®rst stage of HC repeatedly applies some random-start interchange (or other) heuristic to produce a number of alternative facility con®gurations. A su...

We consider the problem of detecting elliptical curves using Hough Transform methods. Storage and efficiency problems are overcome by decomposing the problem into two stages. The first stage uses a novel constraint as the basis for a Hough Transform to detect the ellipse center while the second stage finds the remaining parameters using a simple but efficient focussing implementation of the HT....

We consider the classic continuous-review N stage serial inventory system with a homogeneous Poisson demand arrival process at the most downstream stage (Stage 1). Any shipment to each stage, regardless of its size, incurs a positive fixed setup cost and takes a positive constant lead time. The optimal policy for this system under the long-run average cost criterion is unknown. Finding a good w...

The minimum shift design problem (MSD) is a scheduling problem that commonly arises in workforce management activities. Given a collection of shifts and workforce requirements, the problem consists in finding a minimum cardinality set of work shifts, and the number of workers to assign to each shift, in order to meet (or minimize the deviation from) prespecified staff requirements. This problem...

In this paper, two Benders decomposition algorithms and a novel two-stage integer programming-based heuristic are presented to optimize the beam angle and fluence map in Intensity Modulated Radiation Therapy (IMRT) planning. Benders decomposition is first implemented in the traditional manner by iteratively solving the restricted master problem and then identifying and adding the violated Bende...