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Publicações

Publicações por CEGI

2001

How the FEUP Removal to the New Premises Was Facilitated by the Internal Information System

Autores
Ribeiro, LM; Carravilla, MA; David, G;

Publicação
The Changing Universities - The Role of Technology, The 7th International Conference of European University Information Systems, March 28-30, 2001, Berlin, Germany, Proceedings

Abstract
[No abstract available]

2001

Simulated Annealing for the Unit Commitment problem

Autores
Viana, A; De Sousa, JP; Matos, M;

Publicação
2001 IEEE Porto Power Tech Proceedings

Abstract
Due to their efficiency and their interesting design and implementation features, metaheuristics have been used for a long time with success, in dealing with combinatorial problems. In recent years they have been applied to the Unit Commitment problem with rather interesting results that justify further research in the area. In this paper we present a Simulated Annealing approach to the Unit Commitment problem. Two coding schemes are compared, new neighbourhood structures are presented and some searching strategies are discussed. Preliminary computational experience, performed on some test instances, shows that this approach is flexible, effective and able to handle variations on the problem structure. © 2001 IEEE.

2001

Support vector machines with different norms: motivation, formulations and results

Autores
Pedroso, JP; Murata, N;

Publicação
PATTERN RECOGNITION LETTERS

Abstract
We introduce two formulations for training support vector machines, based on considering the L-1 and L-infinity norms instead of the currently used L-2 norm, and maximising the margin between the separating hyperplane and each data sets using L-1 and L-infinity distances. We exploit the geometrical properties of these different norms. and propose what kind of results should be expected for them. Formulations in mathematical programming for linear problems corresponding to L-1 and L-infinity norms are also provided, for both the separable and non-separable cases. We report results obtained for some standard benchmark problems. which confirmed that the performance of all the formulations is similar. As expected, the CPU time required for machines solvable with linear programming is much shorter.

2001

Wisdom - A UML based architecture for interactive systems

Autores
Nunes, NJ; Cunha, JFE;

Publicação
INTERACTIVE SYSTEMS: DESIGN, SPECIFICATION, AND VERIFICATION

Abstract
The UML is recognized to be the dominant diagrammatic modeling language in the software industry. However, it's support for building interactive systems is still acknowledged to be insufficient. In this paper we discuss and identify the major problems using the UML framework for interactive system development, specifically, in what concerns the architectural issues. Here we present a conceptual architectural model that expands the analysis framework of the Unified Process and the UML profile for software development processes. Our proposal leverages on user-interface domain knowledge, fostering coevolutionary development of interactive systems and enabling artifact change between software engineering and human-computer interaction, under the common notation and semantics of the UML.

2001

Pitfalls and protocols in DEA

Autores
Dyson, RG; Allen, R; Camanho, AS; Podinovski, VV; Sarrico, CS; Shale, EA;

Publicação
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH

Abstract
The practical application of data envelopment analysis (DEA) presents a range of procedural issues to be examined and resolved including those relating to the homogeneity of the units under assessment, the input/output set selected, the measurement of those selected variables and the weights attributed to them. Each of these issues can present difficulties in practice. The purpose of this paper is to highlight some of the pitfalls that have been identified in application papers under each of these headings and to suggest protocols to avoid the pitfalls and guide the application of the methodology. © 2001 Elsevier Science B.V.

2001

Zipf's Law for Web Surfers

Autores
Levene, M; Borges, J; Loizou, G;

Publicação
Knowledge and Information Systems

Abstract

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