Operations Research in Trasportation and Logistics: a half-day seminar at IDSIA

Istituto Dalle Molle di studi sull'intelligenza artificiale

Data d'inizio: 12 Settembre 2007

Data di fine: 13 Settembre 2007

A series of seminars on recent advances in Operations Research and their application to large and complex industrial-scale problems in transporation and logistics.

Place: SUPSI, Galleria 2, 6928 Manno
Room: Primavera
Date: Tuesday, 11 September 2007
Time: 9:00-12:00
Admission: Free

9:00-9:40
Luca Maria Gambardella, IDSIA
METAHEURISTICS FOR TRANSPORT AND LOGISTICS

An overview of the recent research and applied activities in the area of transport and logistic is presented. We start by presenting the work done in La Spezia Container Terminal to optimize ships loading and unloading and resources allocation. Next Platform Project is presented with emphasis on the simulation and optimization of a train terminal in case of rail/road synchronization. Last industrial vehicle routing projects based on ant colony optimization are presented.

9:40-10:20
Ilaria Vacca, EPFL
OPTIMIZATION AT CONTAINER TERMINALS

Over the last years, international sea-freight container transportation has grown dramatically and container terminals play nowadays a key-role in the global shipping network. The increased competitiveness among terminals requires more and more efficiency in container operations, both along the quayside and within the yard, in order to minimize ship's turnaround time. Operations research methods and techniques are therefore worth being used in optimizing terminal operations.
In this work, we first give an overview of decision problems which arise in the management of a container terminal (e.g. berth allocation, crane scheduling, storage policies and strategies, transfer operations) and we briefly describe models and methods presented in the literature. Then, starting from a collaboration with some of the busiest ports in Europe, we have identified some critical issues which will be illustrated: in particular, we focus on the impact that gate operations and transshipment operations have on the yard and we propose a new approach to the yard management which takes into account these interactions. We conclude with suggestions of possible research tracks and open issues.

10:20-10:40 Break

10:40-11:20
Roberto Montemanni, IDSIA
ANT COLONY SYSTEMS FOR LARGE SEQUENTIAL ORDERING PROBLEMS

The sequential ordering problem ([1]) is a version of the asymmetric traveling salesman problem where precedence constraints on vertices are imposed. A tour is feasible if these constraints are respected, and the objective is to find a feasible solution with minimum cost.
The sequential ordering problem models a lot of real world applications, mainly in the fields of transportation and production planning.
We propose an extension of a well known ant colony system for the problem, aiming at making the approach more efficient on large problems. The extension is based on a problem manipulation technique that heuristically reduces the search space.
Computational results, where the extended ant colony system is compared to the original one, are finally presented.


11:20-12:00
Matteo Salani, EPFL
A BRANCH-AND-PRICE ALGORITHM FOR VEHICLE ROUTING PROBLEM WITH SOFT TIME WINDOWS

The Vehicle Routing Problem with Time Windows consists of computing a minimum cost set of routes for a fleet of vehicles of limited capacity visiting a given set of customers with known demand, with the additional constraint that each customer must be visited in a specified time window.
We consider the case in which time window constraints are relaxed into "soft" constraints, that is penalty terms are added to the solution cost whenever a vehicle serves a customer out of its time window. We present a branch-and-price algorithm which is the first exact optimization algorithm for this problem.