It is a fundamental decision making process in container terminals to allocate container transporting works among ALVs. Nowadays, container terminals tend to be larger in storage space and more efficient in handling. As a result, estimations of ALV travel times could be inaccurate, the scale of ALV work allocation could be quite large, and a fixed handling sequence could be hardly ensured befor...

In this research effort, we study three exterior penalty function approaches for solving linear programming problems. These methods are an active set l 2 penalty approach (ASL2), an inequality-equality based l 2 penalty approach (IEL2), and an augmented Lagrangian approach (ALAG). Particular effective variants are presented for each method, along with comments and experience on alternative algo...

This paper deals with the assembly line balancing problem with incompatibilities between tasks with two hierarchical objectives: minimising the number of stations, and once these are fixed, minimising the cycle time. It is solved through CPLEX optimiser software, in which we have introduced a bounding procedure and an exploration strategy based on greedy heuristic priority rules.

This paper illustrates how large instances of the linear ordering problem can be effectively modeled and solved as unconstrained quadratic binary programs (UQP). Computational experience comparing a basic tabu search code for UQP to the state-ofthe-art commercial code (CPLEX) demonstrates the viability and attractiveness of our approach.

In this report we discuss the Vehicle Routing Problem with Skill Sets. We first provide an Integer Programming formulation for the problem, which we solve optimally using CPLEX for small instances. We then present a local search algorithm to solve larger instances.

In this paper, we present a capacitated multiple allocation hub location problem, which arose from a network design problem in German wagonload traffic. We develop heuristic solution approaches based on local improvements. We solve the problem with the heuristics and CPLEX on test data sets provided by our partner Deutsche Bahn AG. The computational results are presented and compared.

A small but notoriously hard integer program formulated by Donald Knuth fifty years ago is solved by three versions of a lexicographic algorithm using Gomory cuts. The lexicographic cutting plane algorithms are faster than CPLEX on this problem by a factor of at least 20.

We compiled an improved version of the G-VRP model of Erdogan and Miller-Hooks (2012) and used it to solve the set of small G-VRP benchmark instances with CPLEX. To be concise, we use the original notation from Erdogan and Miller-Hooks (2012) to describe our model:

In wagonload traffic, a production form in railway freight traffic, small groups of wagons have to be transported. In order to decrease transportation costs, wagons from different relations are consolidated. In railyards trains can be separated and rearranged to new trains. The costs arising from this process, which is called reclassification, must be balanced with the transportation costs. The...