2016
Authors
Mourato, M; Moreira, JM; Correia, T;
Publication
Proceedings of the Workshop on Large-scale Learning from Data Streams in Evolving Environments (STREAMEVOLV 2016) co-located with the 2016 European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML/PKDD 2016), Riva del Garda, Italy, September 23, 2016.
Abstract
Many water boiler manufacturers are not able to detect the occurrence of failures in the machines they produce before they can pose inconvenience and sometimes danger for costumers and workers. Moreover, the number of boilers that have to be monitored, are many times in the range of the thousands or even millions, proportionaly to the number of costumers a company possesses. The detection of these failures in real time, would provide a significant improvement to the perception that consumers have of a certain company, since, if these failures occur, maintenance services can be deployed almost as soon as a failure happens. In this paper, an application prototype capable of monitoring and preventing failures in domestic water boilers, on the y, is presented. This application evaluates measurements which are performed by sensors within the boilers, and identifies the ones that greatly differ from those received previously, as new data arrives, detecting tendencies which might illustrate the occurrence of a failure. The incremental local outlier factor is used with an approach based on the interquatile range measure to detect the outlier factors that should be analysed.
2016
Authors
Nikhalat Jahromi, H; Bell, MGH; Fontes, DBMM; Cochrane, RA; Angeloudis, P;
Publication
ENERGY POLICY
Abstract
The importance of liquefied natural gas (LNG) is rising as demand for it grows rapidly and steadily due to growth in energy demand, the transition to a low carbon economy and the longer distances over which natural gas is now traded. Given its importance, this work proposes an optimization model that assists to decide on when and where LNG should be delivered by coordinating tanker type, assignment and routing, inventory management, contract obligations, arbitrage and uncommitted LNG. The model maximizes the profit mainly by taking advantage of price differences between different markets. The contributions of this work are twofold. First, following the analysis of expenses and revenues, a new mixed integer programming model for LNG liquefaction and shipping is proposed from a corporate finance perspective. Furthermore, a solution approach for it is implemented and tested. Second, the model is used to derive a short term trade policy for the Middle Eastern LNG producers regarding the spot sale of their uncommitted product to Japan or to the UK, namely to: dispatch to whichever market has the higher current spot price, regardless of the variability of the transport expenses.
2016
Authors
Fathi, M; Rodriguez, V; Fontes, DBMM; Alvarez, MJ;
Publication
INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH
Abstract
The Assembly Line Part Feeding Problem (ALPFP) is a complex combinatorial optimisation problem concerned with the delivery of the required parts to the assembly workstations in the right quantities at the right time. Solving the ALPFP includes simultaneously solving two sub-problems, namely tour scheduling and tow-train loading. In this article, we first define the problem and formulate it as a multi-objective mixed-integer linear programming model. Then, we carry out a complexity analysis, proving the ALPFP to be NP-complete. A modified particle swarm optimisation (MPSO) algorithm incorporating mutation as part of the position updating scheme is subsequently proposed. The MPSO is capable of finding very good solutions with small time requirements. Computational results are reported, demonstrating the efficiency and effectiveness of the proposed MPSO.
2016
Authors
Pinto, AA; Almeida, JP; Parreira, T;
Publication
JOURNAL OF DYNAMICS AND GAMES
Abstract
We develop a theoretical framework to study the location-price competition in a Hotelling-type network game, extending the Hotelling model, with linear transportation costs, from a line (city) to a network (town). We show the existence of a pure Nash equilibrium price if, and only if, some explicit conditions on the production costs and on the network structure hold. Furthermore, we prove that the local optimal localization of the firms are at the cross-roads of the town.
2016
Authors
Pinto, AA; Parreira, T;
Publication
JOURNAL OF DYNAMICS AND GAMES
Abstract
For the quadratic Hotelling model, we study the optimal localization and price strategies under incomplete information on the production costs of the firms. We compute explicitly the pure Bayesian-Nash price duopoly equilibrium and we prove that it does not depend upon the distributions of the production costs of the firms, except on their first moments. We find when the maximal differentiation is a local optimum for the localization strategy of both firms.
2016
Authors
Ferreira, M; Almeida, JP; Oliveira, BMPM; Pinto, AA;
Publication
Springer Proceedings in Mathematics and Statistics
Abstract
We consider an R&D investment function in a Cournot duopoly competitionmodel inspired in the logistic equation. We study the economical effects resulting from the firms having different R&D efficiencies. We present three cases: (1) both firms are efficient and have the same degree of efficiency; (2) both firms are less efficient and have the same degree of efficiency; (3) firms are asymmetric in terms of the efficiency of their R&D investment programs.We study the myopic dynamics on the production costs obtained from investing the Nash investment equilibria. © Springer-Verlag Berlin Heidelberg 2016.
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