CESE - Indexed Articles in Journals

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    Dynamic VRP in pharmaceutical distribution - a case study
    ( 2006) José Miguel de Magalhães ; Jorge Pinho de Sousa
    In recent years, the pharmaceutical sector has gone through deep changes, partially due to the ageing of the population and to the increasing of costs in health care services. With margins that are getting lower and lower, the drug distribution problem to pharmacies has become much more important, particularly in large metropolitan areas. As pharmacies demand shorter delivery times, vehicle routing and scheduling problems become harder for distributors. It is recognized that the traditional system based on fixed routes does not fulfil the expectations of pharmacies and may, in some cases, be quite inefficient for distributiors. In this work, a case study has been carried out and a change of the traditional approach is proposed, by adopting a system of variable routes that are dynamically designed, based on orders that are constantly arriving along the day. A dynamic algorithm is therefore proposed, meant to be run several times a day. It has four phases: first, a clustering of th
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    Single machine multi-product capacitated lot sizing with sequence-dependent setups
    ( 2007) Diego Klabjan ; Bernardo Almada-Lobo ; Maria Antónia Carravilla ; José Fernando Oliveira
    In production planning in the glass container industry, machine-dependent setup times and costs are incurred for switch overs from one product to another. The resulting multi-item capacitated lot-sizing problem has sequence-dependent setup times and costs. We present two novel linear mixed-integer programming formulations for this problem, incorporating all the necessary features of setup carryovers. The compact formulation has polynomially many constraints, whereas the stronger formulation uses an exponential number of constraints that can be separated in polynomial time. We also present a five-step heuristic that is effective both in finding a feasible solution (even for tightly capacitated instances) and in producing good solutions to these problems. We report computational experiments.
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    Improving the quality of collaboration requirements for information management through social networks analysis
    ( 2007) Carla Pereira ; António Lucas Soares
    The right choice of the method of organizational analysis to use is a key factor in the process of requirements analysis and specification of an information system. Although a high number of approaches of organizational analysis exist, the choice of the most appropriate option for each concrete case will influence the quality of the results obtained in the analysis of requirements and consequent specification. This paper present a new way for organizational analysis to improve the quality of the requirements of systems that support information management and where collaboration is an important aspect. This is achieved through the application of the social network analysis approach, applied to refine, classify and prioritize the requirements for collaboration and information management in an organization. The paper begins by analysing shortly content management systems and wiki systems as IT platforms for collaboration and information management. After having described the method, a practical case of application of SNetCol method to a R&D institution is presented. The paper finishes by presenting the results of the evaluation of the two particular technological options considered for satisfying the specified requirements are described.
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    Simple Meta-heuristics using the simplex algorithm for non-linear programming
    ( 2007) João Pedro Pedroso
    In this paper we present an extension of the Nelder and Mead simplex algorithm for non-linear programming, which makes is suitable for both unconstrained and constrained optimisation. We then explore several extensions of the method for escaping local optima, and which make it a simple, yet powerful tool for optimisation of nonlinear functions with many local optima. A strategy which proved to be extremely robust was random start local search, with a correct, though unusual, setup. Actually, for some of the benchmarks, this simple meta-heuristic remained as the most e®ective one. The idea is to use a very large simplex at the begin; the initial movements of this simplex are very large, and therefore act as a kind of ¯lter, which naturally drives the search into good areas. We propose two more mechanisms for escaping local optima, which, still being very simple to implement, provide better results for some dif- ¯cult problems.
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    Cutting and packing
    ( 2007) José Fernando Oliveira ; Gerhard Wäscher
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    Critical technologies for the North of Portugal in 2015: the case of ITCE sectors - information technologies, communication and electronics
    ( 2007) Luís Carneiro ; António Carrizo ; Marta Tavares
    The Commission for Coordination and Regional Development of the North of Portugal (CCDR-N) promoted NORTINOV 2015, a project created to define a regional innovation strategy for the North of Portugal based on automotive clusters and Information Technology, Communication and Electronics (ITCE) clusters. Accordingly, it developed a technology forecast for the year 2015 in order to help the North of Portugal cope with the intensifying global competition and rapid technological changes. This paper describes the methodology used to identify critical technologies for the regional economy of the North of Portugal under the project NORTINOV 2015. It involved three main steps: technology identification and study, in which a list of emerging technologies was implemented; refinement of emerging technologies, in which 90 technologies were identified and finally, classification and hierarchisation of technologies, in which 30 technologies were identified as critical for the crafting of regional innovation strategy. In this final step, a workshop involving major stakeholders of the three clusters under study played a major role.
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    Heuristics for a dynamic rural postman problem
    ( 2007) José Soeiro Ferreira ; António Miguel Gomes ; Luís Miguel Moreira ; José Fernando Oliveira
    This paper presents a very special cutting path determination problem appearing in a high precision tools factory, and provides two new heuristics for its resolution. Particular features of both the cutting process, and of the material to be cut, bring in a set of unusual constraints, when compared with other cutting processes, which confer additional complexity and originality to the problem. In particular, this is a matter of practical and economic relevance, since the solution methods are intended to be implemented in a real-life industrial environment. The concept of dynamic graph is exploited to deal with the arc routing problem under study, which is modelled as a dynamic rural postman problem. The constructive heuristics developed, the “higher up vertex heuristic” (HUV) and the “minimum empty path heuristic” (MEP) are tested with real data sets.
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    The geometry of nesting problems: A tutorial
    ( 2008) José Fernando Oliveira ; Julia A. Bennel
    Cutting and packing problems involving irregular shapes is an important problem variant with a wide variety of industrial applications. Despite its relevance to industry, research publications are relatively low when compared to other cutting and packing problems. One explanation offered is the perceived difficulty and substantial time investment of developing a geometric tool box to assess computer generated solutions. In this paper we set out to provide a tutorial covering the core geometric methodologies currently employed by researchers in cutting and packing of irregular shapes. The paper is not designed to be an exhaustive survey of the literature but instead will draw on the literature to illustrate the theory and implementation of the approaches. We aim to provide a sufficiently instructive description to equip new and current researchers in the area to select the most appropriate methodology for their needs.
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    Hierarchical Clustering of Time-Series Data Streams
    ( 2008) João Pedro Pedroso ; Pedro Pereira Rodrigues ; João Gama
    This paper presents and analyzes an incremental system for clustering streaming time series. The Online Divisive-Agglomerative Clustering (ODAC) system continuously maintains a tree-like hierarchy of clusters that evolves with data. ODAC uses a top-down strategy. The splitting criterion is a correlation-based dissimilarity measure among time series, splitting each node by the farthest pair of streams, which defines the diameter of the cluster. In stationary environments expanding the structure leads to a decrease in the diameters of the clusters. The system uses a merge operator, which agglomerates two sibling clusters, in order to react to changes in the correlation structure between time series. The split and merge operators are triggered in response to changes in the diameters of existing clusters. The system is designed to process thousands of data streams that flow at high-rate. The main features of the system include update time and memory consumption that do not depend on the number of examples in the stream. Moreover, the time and memory required to process an example decreases whenever the cluster structure expands. Experimental results on artificial and real data assess the processing qualities of the system, suggesting competitive performance on clustering streaming time series, exploring also its ability to deal with concept drift.
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    Fast solutions for UC problems by a new metaheuristic approach
    ( 2008) Ana Viana ; Jorge Pinho de Sousa ; Manuel Matos
    Due to its combinatorial nature, the Unit Commitment problem has for long been an important research challenge, with several optimization techniques, from exact to heuristic methods, having been proposed to deal with it. In line with one current trend of research, metaheuristic approaches have been studied and some interesting results have already been achieved and published. However, a successful utilization of these methodologies in practice, when embedded in Energy Management Systems, is still constrained by the reluctance of industrial partners in using techniques whose performance highly depends on a correct parameter tuning. Therefore, the application of metaheuristics to the Unit Commitment problem does still justify further research. In this paper we propose a new search strategy, for Local Search based metaheuristics, that tries to overcome this issue. The approach has been tested in a set of instances, leading to very good results in terms of solution cost, when compared either to the classical Lagrangian Relaxation or to other metaheuristics. It also drastically reduced the computation times. Furthermore, the approach proved to be robust, always leading to good results independently of the metaheuristic parameters used.
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    Defining the regional innovation strategy for the year 2015: the case of the ITCE clusters in the North of Portugal
    ( 2008) Catarina Selada ; António Carrizo ; Luís Carneiro
    This paper describes the methodology and the definition of the regional innovation strategy, based on the Information Technology, Communications and Electronics (ITCE) clusters, for the North of Portugal under the project NORTINOV 2015, which was promoted by the commission for the coordination and regional development of the north of Portugal (CCDR-N) under the NORTINOV programme. Three strategic lines were proposed to achieve a regional innovation strategy for the ICTE cluster for the year 2015: the strategic line, in order to create conditions for the development of innovative clusters, the sustainability line, in order to facilitate the interaction with other clusters, and the structural line, in order to position the North region as a world-class region.
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    A note on "the capacited lot-sizing and scheduling problem with sequence-dependent setup costs and setup times"
    ( 2008) Maria Antónia Carravilla ; Bernardo Almada-Lobo ; José Fernando Oliveira
    Abstract Gupta and Magnusson [The capacitated lot-sizing and scheduling problem with sequence-dependent setup costs and setup times. Computers and Operations Research 2005;32(4):727–47] develop a model for the single machine capacitated lot-sizing and scheduling problem (CLSP) with sequence dependent setup times and setup costs, incorporating all the usual features of setup carryovers. In this note we show that this model does not avoid disconnected subtours. A new set of constraints is added to the model to provide an exact formulation for this problem.
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    Interoperability in Collaborative Networks: Independent and industry-specific initiatives - The case of the footwear industry
    ( 2008) Claudia Chituc ; César Toscano ; Américo Azevedo
    The development of information and communication technologies and turbulent market conditions have forced enterprises to adapt their way of undertaking business, from traditional practices to e-business. In this context, achieving seamless interoperability among heterogeneous organizations becomes a critical issue. This article has two main objectives: (1) to present a review of the most relevant approaches aiming at achieving seamless interoperability in a collaborative networked environment. In this sense, major interoperability issues (e.g., interoperability requirements, technologies) are discussed, and the most significant independent (e.g., ebXML) and industry-specific initiatives (e.g., RosettaNet, papiNet, TexWeave) are analyzed; (2) to introduce a recently developed two-layered operational infrastructure aiming at attaining seamless interoperability in the footwear industry (the up-stream segment), based on the requirements identified for this sector in a recent industry survey conducted at European level. Other relevant initiatives targeting this sector are also analyzed, emphasizing the innovative aspects and advantages of this approach.
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    Collaborative business frameworks comparison, analysis and selection: an analytic perspective
    ( 2009) Américo Azevedo ; César Toscano ; Claudia-Melania Chituc
    Several e-business frameworks are currently available, which are aimed at modelling e-business. The aim of this article is to analyse and compare relevant industry-neutral and industry-specific e-business frameworks currently in use, emphasising their strengths and weaknesses towards seamless interoperability in a collaborative networked environment. Their main differences and similarities are underlined based on an analytical model for e-business frameworks comparison. The applicability of the Analytic Hierarchy Process multi-criteria method in e-business frameworks selection is discussed. These analytical approaches are then illustrated with two real cases from industry.
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    'Heuristic approaches to large-scale periodic packing of irregular shapes on a rectangular sheet'.
    ( 2009) Maria Teresa Costa ; António Miguel Gomes ; José Fernando Oliveira
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    "A tutorial in irregular shape packing problems"
    ( 2009) Julia A. Bennell ; José Fernando Oliveira
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    Partner selection in virtual enterprises: a multi-criteria decision support approach
    ( 2009) José António Crispim ; Jorge Pinho de Sousa
    Partner selection in virtual enterprises (VE) can be viewed as a multi-criteria decision making problem that involves assessing trade-offs between conflicting tangible and intangible criteria. In general, this is a very complex problem due to the dynamic topology of the network, the large number of alternatives and the different types of criteria. In this paper we propose an exploratory process to help the decision-maker obtain knowledge about the network in order to identify the criteria and the companies that best suit the needs of each particular project. This process involves a multi-objective tabu search metaheuristic designed to find a good approximation of the Pareto front, and a fuzzy TOPSIS algorithm to rank the alternative VE configurations. In the exploratory phase we apply clustering analysis to confine the search according to the decision-maker beliefs, and case base reasoning, an artificial intelligence approach, to totally or partially construct VEs by reusing past experiences. Preliminary computational results clearly demonstrate the potential of the approach for practical application.
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    A framework proposal for seamless interoperability in a collaborative networked environment
    ( 2009) Claudia Chituc ; Américo Azevedo ; César Toscano
    The advances in information and communication technologies and economic factors impelled organizations to engage in new forms of collaboration, such as collaborative networks. They require adequate frameworks, architectures, tools and platforms to support interoperability among heterogeneous and geographically distributed organizations. Despite the high number of research projects in this area, existing tools and infrastructures, this objective has not been totally achieved. The aim of this research work is to advance the research in the area of interoperability in collaborative networks. A conceptual framework towards seamless interoperability in a collaborative-competitive economic networked environment is described, which comprises six elements: (1) a messaging service; (2) a collaboration profile/agreement definition and management service; (3) five clusters of collaborative activities; (4) a centralized repository; (5) a set of business documents and a set of contracting documents; (6) a performance assessment service. The functionality of the conceptual framework proposed is illustrated with a real implementation case targeting the footwear industry. The proposed conceptual framework is then compared with relevant e-business frameworks.
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