Browsing by Issue Date, starting with "2009-12"
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- Optimizing Multiple Sequence Alignment by Improving Mutation Operators of a Genetic AlgorithmPublication . Silva, Fernando José Mateus da; Pérez, Juan Manuel Sánchez; Pulido, Juan Antonio Gómez; Rodríguez, Miguel A. Vega; Silva, Fernando;Searching for the best possible alignment for a set of sequences is not an easy task, mainly because of the size and complexity of the search space involved. Genetic algorithms are predisposed for optimizing general combinatorial problems in large and complex search spaces. We have designed a Genetic Algorithm for this purpose, AlineaGA, which introduced new mutation operators with local search optimization. Now we present the contribution that these new operators bring to this field, comparing them with similar versions present in the literature that do not use local search mechanisms. For this purpose, we have tested different configurations of mutation operators in eight BAliBASE alignments, taking conclusions regarding population evolution and quality of the final results. We conclude that the new operators represent an improvement in this area, and that their combined use with mutation operators that do not use optimization strategies, can help the algorithm to reach quality solutions.
- Software projects’ most important activities of quality management: A Delphi studyPublication . Catarino, Márcia Filipa Lopes; Gonçalves, Dulce Cristina dos Santos Iria; Pereira, António Manuel de Jesus; Varajão, João Eduardo Quintela Alves de Sousa;Quality management is a very important contributor for the success of software project management. In quality management area we can find multiple activities to carry out, however organizations cannot always execute all those tasks and many times it is indispensable to make choices about what can and should be made. In order to help the organizations to identify the most important activities in quality management, we carried out a Delphi study with the participation of several senior project managers. The result is the identification of several groups of activities, ordered by importance for the project success.
- Effect of asymmetrical rolling and annealing the mechanical response of an 1050-o sheetPublication . Simões, Fábio; Sousa, Ricardo J. Alves de; Grácio, José J. A.; Barlat, Frédéric; Yoon, Jeong WhanThe asymmetrical rolling process has been studied as a way to promote intense shear deformations across the sheet thickness. These shear deformations may lead, given the proper conditions, to the development of shear texture components ({001}<110>, {111}<110> and {111}<112>) and also grain refinement. In this work, a 1050-O sheet is asymmetrically rolled and annealed. Conventional rolling is also performed, for comparison purposes. Shear texture components are obtained for the asymmetrically rolled specimens, and seem to be retained after annealing. Differences in mechanical response between asymmetrical and conventionally rolled specimens, as well as texture evolution after heat treatment processing are inferred based on experimental tensile and shear tests. Numerical simulations are used to help explain the differences found on experimental tests. It is proven that it is difficult to spread shear texture through the entire sheet thickness from a general asymmetric rolling process. Based on the fact, future research is discussed at closure.
- Gastronomy as main attraction of a tourism destination Case Study of Mealhada – PortugalPublication . Oliveira, Simão; Coelho, Júlio; Gúzman, TomásThis study demonstrates that the gastronomy may be in fact the main tourist attraction of a destination. Although the classical models do not refer gastronomy as relevant tourism attraction, in fact, it can be. Mealhada is a successful tourism destination, however, the dependence on a single attraction may compromise the sustainability of the destinition in the future and at various levels
- GRASP and grid computing to solve the location area problemPublication . Almeida da Luz, Sónia Maria; Rodriguez-Hermoso, Manuel M.; Vega-Rodriguez, Miguel A.; Gomez-Pulido, Juan A.; Sanchez-Perez, Juan M.In this paper we present a new approach based on the GRASP (Greedy Randomized Adaptive Search Procedure) metaheuristic to solve the Location Area (LA) problem over a grid computing environment. All the experiments carried out to complete this study were executed in a real grid environment provided by a virtual organization of the European project EGEE. These experiments were divided into sequential and parallel executions with the intention of analyzing the behavior of the different variants of GRASP when applied to the LA problem. We have used four distinct test networks and also decided to compare the results obtained by this new approach with those achieved through other algorithms from our previous work and also by other authors. The experimental results show that this GRASP based approach is very encouraging because, with the grid computing, the execution time is much more reduced and the results obtained are very similar to those of other techniques proposed in the literature.
- A Practical Solution for Automatic Service Discovery and Usage over Resource Poor Ad-hoc Sensor NetworksPublication . Costa, Nuno; Pereira, António; Serôdio, CarlosAd-hoc networks present new challenges due to its mobility, lack of infrastructure and resource limited devices. This means that service discovery (and usage) protocols targeted for traditional networks are not suitable for ad-hoc networks because they usually rely on the fixed and high availability characteristics of nodes to run important services. Ad-hoc networks need service discovery protocols compliant with its mobility and changing topology. In this paper we present a practical solution capable of provide automatic service discovery and usage over ad-hoc networks of resource poor sensor nodes. The solution was not developed from the ground-up. Instead, it was based on a (successfully) solution for traditional networks but then modified to address ad-hoc networks while keeping it original semantics.
- Integration of Resource Poor Wireless Sensor Networks into Smart SpacesPublication . Costa, Nuno; Pereira, António; Serôdio, CarlosWireless Sensor networks (WSNs) have been referred to as one part of the background infrastructure required to achieve ubiquitous computing, where smart spaces are included. For instance, WSNs could be especially useful to compute the user context or even 'context' of mobile resources in general. To serve this purpose, wireless sensor network must expose some sort of service discovery and usage capability and be compatible with the nowadays ubiquitous technologies. In this paper we present a practical approach to bring WSNs, specially the ones built from resource poor sensor nodes, to participate into smart environments as ubiquitous devices. The approach addresses device heterogeneity, uses the state of the art and ubiquitous TCP/IP communication stack, is service driven and do not rely in any external resource rich device. As a result, we successfully created a Java based service discovery and usage protocol that is compliant with ad-hoc networks and resource constrained devices and a framework capable of produce the source and binary code ready to run on both resource constrained sensor nodes and PCs.
- Solving a Realistic Location Area Problem Using SUMATRA Networks with the Scatter Search AlgorithmPublication . Luz, Sónia Maria Almeida da; Vega-Rodríguez, Miguel A.; Gómez-Pulido, Juan A.; Sánchez-Pérez, Juan M.This paper presents a new approach based on the Scatter Search (SS) algorithm applied to the Location Management problem using the Location Area (LA) scheme. The LA scheme is used to achieve the best configuration of the network partitioning, into groups of cells (location areas), that minimizes the costs involved. In this work we execute five distinct experiments with the aim of setting the best values for the Scatter Search parameters, using test networks generated with realistic data [1]. We also want to compare the results obtained by this new approach with those achieved through classical strategies, other algorithms from our previous work and also by other authors. The simulation results show that this SS based approach is very encouraging.
- A Java Software Stack for Resource Poor Sensor Nodes: Towards Peer-to-Peer JiniPublication . Costa, Nuno; Pereira, António; Serôdio, CarlosSensor networks have been referred to as part of the background infrastructure required to achieve ubiquitous computing. This has recently promoted a considerable amount of attention from the research community that concluded that existing protocols and techniques for service discovery, such as JINI or UPnP are not suitable for the case of resource poor, battery-powered sensor nodes. We do not really agree with this approach. We think that those protocols could be a good starting point to "power-up" sensor nodes with poor resources for ubiquitous computing support. Starting from this principle and recognizing that existing sensor node system software is not suitable for our purpose, we decided to build a new sensor node software stack. The result was a stand-alone Java Virtual Machine, suitable for sensor nodes with poor resources, an implementation of the ubiquitous TCP/IP communication stack and Jini based middleware to achieve automatic service discover and usage. This software stack was tailored to perfectly fit in the state-of-the-art Mica2 class of sensor nodes.
- Multiobjective frequency assignment problem using the MO-VNS and MO-SVNS algorithmsPublication . Maximiano, Marisa; Vega-Rodriguez, Miguel A.; Gomez-Pulido, Juan A.; Sanchez-Perez, Juan M.In GSM networks, the Frequency Assignment is a critical task for the mobile operators. In this paper we study different multiobjective metaheuristics to address the Frequency Assignment problem (FAP). In fact, solving optimization problems with multiple (often conflicting) objectives is, generally, a very difficult goal. This is the scenario in the FAP, where it is sought an assignment of frequencies to a number of transmitters in as efficient way as possible. The multiobjective FAP tries to minimize the number of interferences caused when a limited number of frequencies needs to be assigned to a high number of transceivers. Besides these interferences costs, the separation costs are also considered. Our approach uses a Multiobjective Variable Neighborhood Search (MO-VNS) algorithm and also its variant Multiobjective Skewed Variable Neighborhood Search (MO-SVNS). Two real-world GSM networks were used, currently being in operation, to test the presented metaheuristics.