Abstract
Markov models have been widely used for modelling users' web navigation behaviour. In previous work we have presented a dynamic clustering-based Markov model that accurately represents second-order transition probabilities given by a collection of navigation sessions. Herein, we propose a generalisation of the method that takes into account higher-order conditional probabilities. The method makes use of the state cloning concept together with a clustering technique to separate the navigation paths that reveal differences in the conditional probabilities. We report on experiments conducted with three real world data sets. The results show that some pages require a long history to understand the users choice of link, while others require only a short history. We also show that the number of additional states induced by the method can be controlled through a probability threshold parameter.

Abstract
Ranking problems arise from the knowledge of several binary relations defined on a set of alternatives, which we intend to rank. In a previous work, the authors introduced a tool to confirm the solutions of multi-attribute ranking problems as linear extensions of a weighted sum of preference relations. An extension of this technique allows the recognition of critical preference pairs of alternatives, which are often caused by inconsistencies. Herein, a confirmation procedure is introduced and applied to confirm the results obtained by a multi-attribute decision methodology on a tender for the supply of buses to the Porto Public Transport Operator.

Abstract

Abstract
In this paper will be compared, by means of a next event dynamic simulation, two different stock refill policies applied to the same in-lined one-product Supply Chain. The first method is the Japanese method usually known as KANBAN(1) (similar to the "Two Bins" method, in terms of dynamics), and the second is a naive method named by the authors the "BanKan" for the reasons that will be explained later in this text. The surprising results obtained show an obvious operational advantage of the naive method, at least under the conditions of the present Supply Chain design and configuration. This method does not make use of any criteria dependent on the actual stock level at the facility, and it was also observed that the materials flow through the Supply Chain as in a "river without dams", and with extremely low local inventory, as it was defended by Taiichi Ohno, the father of just-in-time (JIT) systems, in the 1980s.

Abstract
Data in this article results from a study of simulation about the procurement of addictives for lubricants in the Oil Refinery of Porto (Portugal). Here we describe the real case under study as well as the method we have chosen to board it by means of simulation, which finally leaded us to some interesting results regarding the choices on purchasing the addictives from the suppliers. Costs including transportation, holding and stockouts have been considered during the simulation as well as in the final conclusions, which let us recommend a more frequent reordering of materials at the lubricants plant. This we expect to result in the saving of around 0.3MEURO/year in global costs.

Abstract
This paper describes a case study concerning the teaching of logistics in the Computers and Electrical Engineering degree at FEUP. The logistics course is taken in the last semester of the degree and there are no lectures given by the teachers. All the learning strategy is based upon the autonomous learning capacity of the students, following the widespread citation of Confucius, ‘I hear and I forget. I see and I remember. I do and I understand’. The students are organized in groups and their autonomous work is motivated by the presentation that each group leader has to give every other week. A discussion period follows each presentation, and can be used by the teachers to evaluate the involvement of each member of the group and to complement the presentation whenever necessary. All the students are leaders at least once. The leaders are responsible for the group management and must prepare for the ‘leaders’ meeting', where the presentation session is organized. Assessment is based both on the quality of the presentation and on the technical correctness and completeness in the way subjects are treated and on leadership skills. While the teachers evaluate the two first issues, peers evaluate leadership. © 2004, Taylor & Francis Group, LLC.