DECOM - Departamento de Computação

URI Permanente desta comunidade

http://www.repositorio.ufop.br/handle/123456789/575

Navegar

Navegando DECOM - Departamento de Computação por Data de Publicação

Filtrar resultados por ano ou mês
Agora exibindo 1 - 20 de 501
  • Nenhuma Miniatura disponível
    Item
    Projeto/Reprojeto de bancos de dados relacionais : a ferramenta DB-Tool.
    (1997) Ferreira, Anderson Almeida; Laender, Alberto Henrique Frade; Silva, Altigran Soares da
    This paper describes a tool that supp orts the design and redesign of relational databases The tool produces optimized relational representations of entity relationship ER schemas and is implemented using Informix as its target database management system DBMS The tool operates in two phases In the first phase it receives as input an ER schema and generates a list of commands to implement the corresponding Informix schema In the second phase it receives a list of redesign commands specifying changes to the ER schema and generates a redesign plan to reestructure the database accordingly An example illustrates the use of the tool.
  • Nenhuma Miniatura disponível
    Item
    Scatter search based approach for the quadratic assignment problem
    (1997) Cung, Van Dat; Mautor, Thierry; Michelon, Philippe Yves Paul; Tavares, Andréa Iabrudi
    Scatter search is an evolutionary heuristic, proposed two decades ago, that uses linear combinations of a population subset to create new solutions. A special operator is used to ensure their feasibility and to improve their quality. In this paper, we propose a scatter search approach to the QAP problem. The basic method is extended with intensification and diversification stages and we present a procedure to generate good scattered initial solutions
  • Nenhuma Miniatura disponível
    Item
    A type system for context-dependent overloading.
    (1998) Figueiredo, Lucília Camarão de; Figueiredo, Carlos Camarão de
    This article presents a type system for context-dependent overloading, based on the notion of constrained types. These are types constrained by the definition of functions or constants of given types. This notion supports both overloading and a form of subtyping, and is related to Haskell type classes [11,2], System O [7] and other systems with constrained types. We study an extension of the Damas-Milner system [4,1] with constrained types. The inference system presented uses a context-dependent overloading policy, which is specified by means of a predicate used in a single inference rule. The idea simplifies the treatment of overloading, enables the simplification of inferred types (by means of class type annotations), and is adequate for use in a type system with higher-order types.
  • Nenhuma Miniatura disponível
    Item
    Towards higher-order types.
    (1998) Figueiredo, Carlos Camarão de; Figueiredo, Lucília Camarão de
    This article explores the use of types constrained by the definition of functions of given types. This notion supports both overloading and a form of subtyping, and is related to Haskell type classes and System O. We study an extension of the Damas-Milner system, in which overloaded functions can be defined. The inference system presented uses a context-independent overloading policy, specified by means of a predicate used in a single inference rule. The treatment of overloading is less restrictive than in similar systems. Type annotations are not required, but can be used to simplify inferred types. The work motivates the use of constrained types as parameters of other, higher-order types.
  • Nenhuma Miniatura disponível
    Item
    Evolving visual features and detectors.
    (1998) Guarda, Álvaro; Le Gal, Christophe; Lux, Augustin
    This paper addresses the problemof automatic synthesis of visual detectors. We present a method using genetic techniques to learn visual features and a program which combines and integrates the features in non-linear ways. The method is integrated in a face tracking system to generate a variety of new visual perceptual processes.
  • Nenhuma Miniatura disponível
    Item
    System-level partitioning with uncertainty.
    (1999) Albuquerque, Jones; Coelho Júnior, Claudionor José Nunes; Cavalcanti, Carlos Frederico Marcelo da Cunha; Silva Júnior, Diógenes Cecílio da; Fernandes, Antônio Otávio
    Several models and algorithms have been proposed in the past to generate HW/SW components for system-level designs. However, they were focused on a single designer who had a throughout knowledge of the design. In other words, the decision trade-offs were simplified to a stand-alone developer who did not have to consider individual skills, concurrent development for portions of the design, risk analysis for time-to-market development, nor team load and assignment. In this paper, we propose a design management approach associated with a partitioning methodology to deal with the concurrent design problems of system-level specifications. This methodology allows one to incorporate the uncertainties related to development at the very early stages of the design, and to follow up during the development of a final product.
  • Nenhuma Miniatura disponível
    Item
    Qualidade de serviço IP : nasce uma nova internet.
    (2000) Cavalcanti, Carlos Frederico Marcelo da Cunha; Loureiro, Antônio Alfredo Ferreira; Fernandes, Antônio Otávio; Nogueira, José Marcos Silva
    Por causa do rápido crescimento do tráfego em aplicações de tempo real, as redes de computadores requerem mais funções do que anteriormente oferecidas no passado. Na presente geração da Intemet, constata-se a grande demanda por aplicações comércio eletrônico, de voz e de multimídia. É essencial que a rede suporte diferentes níveis de Qualidade de Serviço (QoS) e cada nível seja associado a um usuário ou a um grupo de usuários distintos. Em resposta ao crescimento da demanda por QoS na Intemet, a Internet Engineering Task Force estabeleceu dois grupos de trabalho denominados DiffServ and IntServ. Este artigo apresenta os principais conceitos e soluções propostas por ambos para prover Qualidade de Serviço, estendendo a arquitetura TCP/IP.
  • Nenhuma Miniatura disponível
    Item
    Melhorando quadros de horário de escolas através de caminhos mínimos.
    (2000) Souza, Marcone Jamilson Freitas; Maculan Filho, Nelson; Ochi, Luiz Satoru
  • Nenhuma Miniatura disponível
    Item
    Engineering the multi-service internet : MPLS and IP-based techniques.
    (2001) Trimintzios, Panos; Georgiadis, Leonidas; Pavlou, George; Griffin, David; Cavalcanti, Carlos Frederico Marcelo da Cunha; Georgatsos, Panos; Jacquenet, C.
    IP Differentiated Services (DiffServ) is seen as the framework to support quality of service (QoS) in the Internet in a scalable fashion, turning it to a global multiservice network. In this context, integrated service/network management and traffic control mechanisms are of paramount importance for service provisioning and network operation, aiming to satisfy the QoS requirements of contacted services while optimizing the use of underlying network resources. In this paper, after briefly introducing an architectural framework for integrated service/network management and control, we concentrate in its traffic engineering aspects comparing and contrasting two different approaches: MPLS-based explicit routed paths and IP-based hop-by-hop routing. We consider relatively longterm network dimensioning based on the requirements of contracted services and subsequent dynamic route and resource management that react in shorter time scales to statistical traffic fluctuations and varying network conditions.
  • Nenhuma Miniatura disponível
    Item
    An architectural framework for providing QoS in IP differentiated services networks.
    (2001) Trimintzios, Panos; Andrikopoulos, Ilias; Pavlou, George; Cavalcanti, Carlos Frederico Marcelo da Cunha; Georgatsos, Panos; Griffin, David; Jacquenet, C.; Goderis, D.; T'Joens, Y.; Georgiadis, Leonidas; Egan, R.; Memenios, G.
    As the Internet evolves, a key consideration is support for services with guaranteed quality of service (QoS). The proposed differentiated services (DiffServ) framework, which supports aggregate traffic classes, is seen as the key technology to achieve this. DiffServ currently concentrates on control/data plane mechanisms to support QoS but also recognises the need for management plane aspects through the bandwidth broker (BB). In this paper we propose a model and architectural framework for supporting end-to-end QoS in the Internet through a combination of both management and control/data plane aspects. Within the network we consider control mechanisms for traffic engineering (TE) based both on explicitly routed paths and on pure node-by-node layer 3 routing. Management aspects include customer interfacing for service level specification (SLS) negotiation, network dimensioning, traffic forecasting and dynamic resource and routing management. All these are policy-driven in order to allow for the specification of high-level management directives. Many of the functional blocks of our architectural model are also features of BBs, the main difference being that a BB is seen as driven purely by customer requests whereas, in our approach, TE functions are continually aiming at optimising the network configuration and its performance. As such, we substantiate the notion of the BB and propose an integrated management and control architecture that will allow providers to offer both qualitative and quantitative QoS-based services while optimising the use of underlying network resources
  • Nenhuma Miniatura disponível
    Item
    An embedded converter from RS232 to universal serial bus.
    (2001) Zuquim, Ana Luiza de Almeida Pereira; Coelho Júnior, Claudionor José Nunes; Fernandes, Antônio Otávio; Oliveira, Marcos Pêgo; Tavares, Andréa Iabrudi
    Universal Serial Bus (USB) is a new personal computer interconnection protocol, developed to make the connection of peripheral devices to a computer easier and more efficient. It reduces the cost for the enduser, improves communication speed and supports simultaneous attachment of multiple devices (up to 127). RS232, in another hand, was designed to single device connection, but is one of the most used communication protocols. An embedded converter from RS232 to USB is very interesting, since it would allow serial-based devices to experience USB advantages without major changes. This work describes the specification and development of such converter and it is also a useful guide for implementing other USB devices. The converter specification was based on Engetron UPS’ serial communication requirements and its implementation uses a Cypress microcontroller with USB support.
  • Nenhuma Miniatura disponível
    Item
    A method for specification of collaborative interfaces through the use of scenarios.
    (2001) Dumont, Anamaria Montandon; Pietrobon, Carlos Alberto Marques
    The complexity and the extension of tasks in the world today demand an extensive interaction among people with different knowledge backgrounds, who need to work in cooperation, aiming at a common goal. In this paper, we present a method to model the tasks and actions that a group of users carries out when working cooperatively through a computational system integace. For this purpose, we use scenarios for requirements gathering for user-cooperative interfaces. Along with the method, we propose the use of a notation that was developed to support interaction characteristics of users in cooperative work.
  • Nenhuma Miniatura disponível
    Item
    Uma heurística para o problema de programação de horários em escolas.
    (2001) Souza, Marcone Jamilson Freitas; Maculan Filho, Nelson; Ochi, Luiz Satoru
    Apresentamos GBT-II, uma heurística para resolver problemas de programação de horários em escolas. A partir de uma solução inicial gerada por um procedimento construtivo parcialmente guloso, um procedimento de Busca Tabu inicia sua pesquisa. Quando uma solução sem sobreposições, mas com, possivelmente, algum outro tipo de inviabilidade, é gerada, acionamos um procedimento chamado intraturmas-Intertumas para tentar recuperar a viabilidade. Sendo bem sucedido, ele é novamente acionado, agora para tentar melhorar a capacidade da agenda dos professores, bem como outras medidas de qualidade. Após um certo número de interações sem melhora, todo o processo, desde a geração de uma solução inicial, é repetido até que uma condição de parada seja satisfeita . Resultados computacionais mostram que a tilização do procedimento Intraturmas-Interturmas faz produzir soluções melhores rapidamente.
  • Nenhuma Miniatura disponível
    Item
    ABCTool - uma ferramenta para cooperação baseada na arquitetura do sistema.
    (2002) Barros, Cynthia Maria Silva de; Pietrobon, Carlos Alberto Marques
    O projeto de um sistema de software pode se tornar um trabalho bastante complexo em se tratando da construção de grandes sistemas. Assim, cada vez mais os projetistas têm reconhecido a importância do design da arquitetura no projeto do sistema com o propósito de facilitar o trabalho de desenvolvimento. Outro aspecto que também tem sido observado é o fato de que estes sistemas são desenvolvidos por grupos de pessoas que trabalham paralelamente e cooperativamente. A dificuldade de comunicação entre a equipe gera problemas na hora da integração das partes que cada um desenvolveu. Esse artigo propõe uma ferramenta de apoio ao desenvolvimento cooperativo de software baseado na arquitetura do sistema sendo desenvolvido.
  • Nenhuma Miniatura disponível
    Item
    Using XML to improve frameworks reuse.
    (2002) Amaral, Juliana Alves; Pietrobon, Carlos Alberto Marques
    This paper presents an approach to promote framework exchange through the use of XML standards. This exchange is quite important for developers’ teams who do not work at the same place neither the same environment, but need to collaborate in common projects. This paper combines the benefits of XML for defining, validating and sharing documents on the Web with the benefits of frameworks and object-oriented Unified Modeling Language (UML). UML-F-X, a extension of UML-F (an extension of UML for framework domain), is then proposed in this paper in order to take advantage of DTD concepts, reducing the semantic loss of framework-DTD mapping. By using standards for storing (UML) and sharing (XML) object-oriented frameworks, development teams using tools from multiple vendors can build and reuse applications in a distributed environment. The objective of this approach is to use the Web as a channel to exchange frameworks, stimulating then the use of this object-oriented technique among software engineers.
  • Nenhuma Miniatura disponível
    Item
    A view on abstract and extensible types.
    (2002) Figueiredo, Lucília Camarão de; Figueiredo, Carlos Camarão de
    This paper presents a type declaration construct which provides either a type synonym, a datatype, an abstract type with views, a subtype of an existing type, or a module (collection of declarations), in the style of modern functional programming languages ahich provide support for parametric polymorphism.
  • Nenhuma Miniatura disponível
    Item
    Simulated annealing approach to solve the daily crew scheduling problem.
    (2002) Silva, Gustavo Peixoto; Souza, Marcone Jamilson Freitas; Alves, José Maria do Carmo Bento
  • Nenhuma Miniatura disponível
    Item
    Geração de números aleatórios.
    (2002) Pereira Junior, Álvaro Rodrigues; Freitas, Maria Eugênia de Almeida; Lacerda, Wilian Soares
    Este artigo aborda a geração de números aleatórios uniformemente distribuídos no intervalo [0,11 utilizando o método do resíduo. A partir desta distribuição, é possível gerar outras atribuições por meio de transformações. Entretanto, é difícil obter uma distribuição perfeita devido às dificuldades computacionais. São apresentados exemplos de geração de números aleatórios com algumas distribuições conhecidas (gaussiana e exponencial) e mostrados os resultados obtidos.
  • Nenhuma Miniatura disponível
    Item
    Syntactic similarity of web documents.
    (2003) Pereira Junior, Álvaro Rodrigues; Ziviani, Nivio
    This paper presents and compares two methods for evaluating the syntactic similarity between documents. The first method uses the Patricia tree, constructed from the original document, and the similarity is computed searching the text of each candidate document in the tree. The second method uses shingles concept to obtain the similarity measure for every document pairs, and each shingle from the original document is inserted in a hash table, where shingles of each candidate document are searched. Given an original doc-ument and some candidates, two methods find documents that have some similarity relationship with the original doc-ument. Experimental results were obtained by using a pla-giarized documents generator system, from 900 documents collected from the Web. Considering the arithmetic ave rage of the absolute differences between the expected and ob-tained similarity, the algorithm that uses shingles obtained a performance of 4,13 % and the algorithm that uses Patricia tree a performance 7.50%
  • Nenhuma Miniatura disponível
    Item
    An early warning system for space-time cluster detection.
    (2003) Assunção, Renato Martins; Tavares, Andréa Iabrudi; Kulldorff, Martin
    A new topic of great relevance and concern has been the design of efficient early warning systems to detect as soon as possible the emergence of spatial clusters. In particular, many applications involving spatial events recorded as they occur sequentially in time require this kind of analysis, such as fire spots in forest areas as in the Amazon, crimes occurring in urban centers, locations of new disease cases to prevent epidemics, etc. We propose a statistical method to test for the presence of space-time clusters in point processes data, when the goal is to identify and evaluate the statistical significance of localized clusters. It is based on scanning the three dimensional space with a score test statistic under the null hypothesis that the point process is an inhomogeneous Poisson point process with space and time separable first order intensity. We discuss an algorithm to carry out the test and we illustrate our method with space-time crime data from Belo Horizonte, a large Brazilian city.