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Biblioteca Digital do IPB (53.442 recursos)

A Biblioteca Digital do IPB, tem por objectivo divulgar e permitir o livre acesso à produção científica produzida pela comunidade académica, promovendo a integração, partilha e a visibilidade da informação científica e garantindo a preservação da memória intelectual do Instituto Politécnico de Bragança.

DIC - CC - Artigos em Actas de Conferências Indexadas

Mostrando recursos 1 - 13 de 13

  1. Computation of conservation laws in optimal control

    Gouveia, Paulo D.F.; Torres, Delfim F.M.
    Making use of a computer algebra system, we define computational tools to identify symmetries and conservation laws in optimal control.

  2. Multivox: conversor texto fala para português

    Teixeira, João Paulo; Freitas, D.; Gouveia, Paulo D.F.; Olaszy, Gabor; Nemeth, G.
    Apresenta-se neste artigo uma visão genérica sobre sistemas de conversão texto-fala. Aborda-se de uma forma mais detalhada o sistema MULTIVOX de conversão texto fala para o português como um modelo de síntese de formantes baseado em regras. Este sistema foi desenvolvido no âmbito da cooperação entre o CEFAT e a Universidade Técnica de Budapeste em duas versões. Uma primeira versão, desenvolvida até 1996, que será descrita por blocos para permitir uma melhor compreensão deste sistema. Uma segunda versão, ainda em desenvolvimento, será apresentada nas suas potencialidades. O sistema corre num processador 386 ou superior com recurso a uma placa de...

  3. Divisão silábica automática do texto escrito e falado

    Gouveia, Paulo D.F.; Teixeira, João Paulo; Freitas, D.
    Este artigo apresenta um algoritmo que permite realizar automaticamente a separação silábica do texto como uma etapa do desenvolvimento de um trabalho mais extenso, que é o estudo de modelos prosódicos para o português europeu, enquadrado no desenvolvimento de um sintetizador de fala. O algoritmo de separação silábica está foi concebido para aplicação em duas situações distintas: na primeira é aplicado ao texto escrito e na segunda à sequência de fonemas realmente produzidos na locução desse mesmo texto. Cada uma das aplicações está envolta nas suas peculiaridades e dificuldades, que são descritas, bem como as soluções adoptadas para a sua...

  4. Computing ODE symmetries from a variational point of view

    Gouveia, Paulo D.F.; Torres, Delfim F.M.

  5. Uma forma bidimensional que maximiza a resistência aerodinâmica newtoniana

    Gouveia, Paulo D.F.; Plakhov, Alexander; Torres, Delfim F.M.
    Um corpo bidimensional, apresentando um ligeiro movimento rotacional, desloca-se num meio rarefeito de partículas que colidem com ele de uma forma perfeitamente elástica. Em investigações que os dois primeiros autores realizaram anteriormente [Plakhov and Gouveia, 2007], procuraram-se formas de corpos que maximizassem a força de travagem do meio ao seu movimento. Dando continuidade a esse estudo, encetam-se agora novas investigações que culminam num resultado que representa um grande avanço qualitativo relativamente aos então alcançados.Esse resultado, que agora se apresenta, consiste numa forma bidimensional que confere ao corpo uma resistência muito próxima do seu limite teórico.

  6. Visualization of domain-specific programs’ behavior

    Oliveira, Nuno; Pereira, Maria João; Cruz, Daniela; Henriques, Pedro
    Program domain concepts are rather complex and low level for a fast assimilation. On the other hand, problem domain concepts are closer to human’s mind, hence they are easier to perceive. Based on Brook’s theory, a full comprehension of a program is only achieved if both domains are connected and visualized in synchronization, resulting on an action-effect visualization. Domain-specific languages, as languages tailored for a specific class of problems, raise the abstraction of the program domain concepts and approximate them to the problem domain’s. This way, a systematic approach can be used to perform the action-effect visualization of a program written in a domain-specific...

  7. Efficient conservative collision detection for populated virtual worlds

    Ramires Fernandes, A.; Deusdado, Leonel
    Large virtual worlds, with considerable level of detail are starting to emerge everywhere, from large areas of actual cities to archaeological reconstructions of large sites. Populating a virtual world adds an extra touch to the visualization of these worlds, but unfortunately it also brings an extra burden to the system. Several tasks are required when adding animated characters to a virtual world, such as collision detection, path planning and other AI algorithms, rendering of dynamic geometry, amongst others. In here a method for efficient and scalable conservative collision detection is presented, that is able to deal with large scenes and...

  8. How to interconnect operational and behavioral views of web applications

    Fonseca, Ruben; Cruz, Daniela; Henriques, Pedro; Pereira, Maria João
    In the context of our research project, we are looking for program comprehension tools that are able to interconnect operational and behavioral views, aiming at aiding the programmer to relate problem and program domains to reach a full understanding of software systems. In particular we have been studying the adaptation of that principle to web applications. In this context, we had designed and implemented a tool called WebAppViewer. In this paper, we emphasize the development of the module (BORS) that is responsible for providing interconnection functionalities and we propose a tool demonstration. A dedicated web server is included in the system to allow the...

  9. Specifying languages using aspect-oriented approach: aspectLISA

    Rebernak, Damijan; Mernik, Marjan; Henriques, Pedro; Cruz, Daniela; Pereira, Maria João
    Object-oriented techniques and concepts have been successfully used in language specification and formalization. They greatly improve modularity, reausability and extensibility. In spite of using 00 paradigms in language specification, some semantic aspects still crosscut many language constructs. Improvements can be achieved with aspect-oriented techniques. The paper describes AspectLISA tool wich uses aspect-oriented approach for language specification (aspect-oriented attribute grammars). An example will be worked out in order to illustrate the approach. We will show how to identify an aspect, specify it in the concrete AspectLisa syntax, and how to gather parts in order to develop a complete language processor.

  10. Visualization/animation of programs based on abstract representations and formal mappings

    Pereira, Maria João; Henriques, Pedro
    In the context of Alma (a system for program visualization and algorithm animation), we use an internal representation-based on the concept of an attributed abstract syntax tree decorated with attribute values, a DAST-to associate (static) figures to grammar rules (productions) and to step over program dynamics executing state changes in order to perform its animation. We do not rely upon any source program annotations (visual/animation statements, or parameters), neither on any special visual data types. On account of such principle, the approach becomes source language independent. It means that we can apply the same visualizer and animator, that is the Alma's...

  11. Grammatical approach to problem solving

    Henriques, Pedro; Kosar, Tomaz; Mernik, Marjan; Pereira, Maria João; Zumer, Viljem
    The paper presents a grammatical approach to problem solving. It supports for-mal software, specification using attribute grammars, from, which, a rapid prototype can be generated as well the incremental, software development. Domain concepts and relationships among them. have to be identified from a problem statement and represented as a context-free grammar. The obtained context-free grammar describes the syntax of a dowain-specific language whose semantics is the same as the functionality of the system under implementation. The semantics of this language is then described using attribute grammars from which a compiler is automatically generated. The execution of a particular programme written...

  12. Grammatical approach to problem solving

    Henriques, Pedro; Kosar, Tomaz; Mernik, Marjan; Pereira, Maria João; Zumer, Viljem
    The paper presents a grammatical approach to problem solving. It supports for-mal software, specification using attribute grammars, from, which, a rapid prototype can be generated as well the incremental, software development. Domain concepts and relationships among them. have to be identified from a problem statement and represented as a context-free grammar. The obtained context-free grammar describes the syntax of a dowain-specific language whose semantics is the same as the functionality of the system under implementation. The semantics of this language is then described using attribute grammars from which a compiler is automatically generated. The execution of a particular programme written...

  13. Visualization/animation of programs in Alma: obtaining different results

    Pereira, Maria João; Henriques, Pedro
    Alma, a system for program animation, receives as input a computer program and produces a sequence of visualizations that will describe its functionality. The system generates automatically program animations basing this process on the internal representation of those programs. The back-end of this system works over at? execution tree (DAST Decorated Abstract Syntax Tree), implementing the animation algorithm. This algorithm uses two bases of rules: visualizing rules (to associate graphical representation with program elements creating a visual description of the program state) and rewriting rules (to change the program state). In this paper the main goal will be to present the...

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