We consider a real-world problem arising in a warehouse for spare parts. Items ordered by customers shall be collected and for this purpose our task is to determine efficient pickup tours within the warehouse. The algorithm we propose embeds a dynamic programming algorithm for computing individual optimal walks through the warehouse in a general variable neighborhood search (VNS) scheme. To enh...

This paper presents a hybrid multi-objective model that combines Integer Programming (IP) and Variable Neighbourhood Search (VNS) to deal with highly constrained nurse rostering problems in modern hospital environments. An IP is first used to solve the subproblem which includes the full set of hard constraints and a subset of soft constrains. A basic VNS then follows as a postprocessing procedu...

In this paper we propose a variable neighbourhood search (VNS) meta-heuristic [25] for the university examination timetabling problem. In addition to a basic VNS method, we introduce a variety of variants which further improve the quality of the results produced by the technique. We also aim to demonstrate that the proposed technique is capable of producing high quality solutions across a wide ...

A major challenge in the initial stage of production planning for the steel industry is the material allocation problem (MAP): finding the best match of orders and materials (steel slabs and coils) with respect to an objective function that takes into account order due dates, preferences for matches, allocated weights, surplus weights of materials, and other factors. The MAP is NP-hard and is d...

We present a data mining approach for reducing the search space of local search algorithms in a class of binary integer programs including the set covering and partitioning problems. The quality of locally optimal solutions typically improves if a larger neighborhood is used, while the computation time of searching the neighborhood increases exponentially. To overcome this, we extract variable ...

The berth allocation problem is to allocate space along the quayside to incoming ships at a container terminal in order to minimize some objective function. We consider minimization of total costs for waiting and handling as well as earliness or tardiness of completion, for all ships. We assume ships can arrive at any given time, i.e., before or after the berths become available. The resulting ...

proposing a robust designed facility location is one of the most effective ways to hedge against unexpected disruptions and failures in a transportation network system. this paper considers the combined facility location/network design problem with regard to transportation link disruptions and develops a mixed integer linear programming formulation to model it. with respect to the probability o...