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Biblioteca Digital do IPB (53.442 recursos)

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Mostrando recursos 1 - 20 de 50

  1. Estrategias para facilitar la comprensión de programas

    Berón, Mario; Uzal, Roberto; Henriques, Pedro; Pereira, Maria João
    La Comprensión de Programas es una disciplina de la Ingeniería de Software cuyo objetivo es proveer Modelos, Métodos, Técnicas y Herramientas para facilitar el estudio y entendimiento de los sistemas de software. A través de un extenso estudio y experiencia en el desarrollo de productos de comprensión se pudo comprobar que el principal desafío en esta área consiste en: Relacionar el Dominio del Problema con el Dominio del programa. El primero hace referencia a la salida del sistema. El segundo a las componentes de software usadas para producir dicha salida. La construcción de este tipo de relación es muy compleja e implica el estudio de disciplinas tales como: Modelos Cognitivos, Visualización de Software, Estrategias de Interrelación de Dominios...

  2. Computing ODE symmetries as abnormal variational symmetries

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

  3. Automatic computation of conservation laws in the calculus of variations and optimal control

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

  4. A double parabola with retroreflection properties

    Gouveia, Paulo D.F.
    This Demonstration shows the reflective behavior of a two-dimensional shape formed by similar arcs of two parabolas. An interesting and unexpected reflective behavior arises when this shape takes a specific configuration, with two parabolas of unit focal length. In this particular configuration it is found that, except for the rays with absolute value of the entry angle less than 19.47º, a ray emerges from the cavity with a trajectory that is nearly opposite to its entry trajectory. This characterizes a cavity with retroreflective behavior. Even in the case of trajectories with entry angle below 19.47º, the exit direction does not...

  5. Reflection of parallel rays by a two-dimensional body of nearly maximal resistance

    Gouveia, Paulo D.F.
    This Demonstration shows a class of nonconvex bodies that maximize resistance as they move forward while slowly rotating through a rarefied medium. This class of shapes yields a resistance very close to the theoretical maximum, improving all previous results found by the authors.

  6. A Maple interface for computing variational symmetries in optimal control

    Gouveia, Paulo D.F.; Torres, Delfim F.M.
    A computer algebra package, for the automatic computation of variational symmetries in optimal control, was recently developed by the authors [2,3]. Now we present a graphical user interface which permit to interact, in a point-and-click environment, with all the previous symbolical tools.

  7. A framework to optimize compilation task

    Matos, Paulo
    Nowadays, compiler construction is supported by several tools, many of them are based on frameworks, composed by several components that can be combined or instantiated to build new components or even entire compilers. This paper is a software engineering exercise applied to the compiler construction tools. It is used a concrete framework for compilers development - the Dolphin, that supplies several components that work over a single code representation model, to show that the simple composition of such components is not enough. It raises serious obstacles that make the compilers construction more arduous. The exercise evolves for a reformulation of the framework, resulting on an independent architecture that could be...

  8. Dolphin-complab: a virtual compilers laboratory

    Matos, Paulo; Henriques, Pedro
    The goal of this paper is to present the Dolphin-COMPilers LABoratory (COMPLAB), an integrated environment conceived for the investigation, teaching, development and use of compilers. It employs Web technologies to make available a virtual laboratory containing a set of functionalities to: implement, analyze, test, evaluate and simulate compiler routines. This environment aims to support the classes of Language Processors of the graduate and post-graduate levels of the Computer Science courses, inside and outside of the classroom. The environment, reachable using a simple Web browser (connected to the Internet), should supply three distinct levels of access that correspond to three distinct...

  9. Dolphin-FEW: an architecture for compilers development, monitoring and use on the web

    Matos, Paulo; Henriques, Pedro
    DOLPHIN is a framework developed to help the construction of high performance, multi-language and retargetable compilers. It is constituted by a set of components, used to build and test new compilers or compiler routines; and by a set of tools, used to access, manage and develop the components. To improve and enlarge the functionalities of the DOLPHIN, several small projects were implemented around the framework, one of them is the DOLPHIN – Front-End for the Web, whose the goal is to build a set of applications to make available via web a set of services related with compilers, namely: an...

  10. Construção dinâmica de um sistema interactivo para visualização do código intermédio do processo de compilação

    Matos, Paulo; Henriques, Pedro
    O DOLPHIN is a framework conceived to help the development of high-performance, multi-language and multi-architecture compilers. It includes several components, one of them is designated by DOLPHIN – Front-End for the Web. This one is responsible for all DOLPHIN items related with the web, namely an integrated development environment that allows, between other things, to observe and analyze, as hiper-text, the information along the compilation process. In this article is introduced a new solution developed with this intent (visualize and analyze the information of the compilation process), with an interactive graphical interface, built dynamically from a description of the information...

  11. Applying compiler technology to solve generic

    Matos, Paulo; Henriques, Pedro
    Compilers are tools that transform a high level programming languages into assem- bly or binary code. The essential of the process is done by the interpretation and the code generation steps, but nowadays most compilers have also a strong component of code optimization, that explore as much as possible the potential of the computer architectures to which the compiler must generate the code. These optimizations are based on the information provided by several analysis processes. This paper present some of these code analysis and optimizations, and shows how they can be used to solve problems or improve the quality of solutions used at areas such as industrial engineer...

  12. Data flow analysis applied to optimize generic workflow problems

    Matos, Paulo; Henriques, Pedro
    The compiler process, the one that transforms a program in a high level language into assembly or binary code, is a much elaborated process that mixes several powerful technologies, some of them developed specifically for this area. Nowadays, compilers are highly developed systems that can analyze and improve quite efficiently the source code, profiting from all the potential of the new processor architectures. This paper introduces a common type of analysis - the Data Flow Analysis – that is used to compute flow-sensitive information about programs, whose results are essential to produce many code optimizations. It is also argued that...

  13. Apoio 3D ao ensino da língua gestual

    Deusdado, Leonel
    There is an agreement on the need of human intervention in the teaching of a sign language; it is also true that there is no dispute in relation to the added value that the new technologies represent as support material in the teaching. We give special emphasis on the technologies that use images and/or models based in three-dimensional graphics to create virtual signers. This paper focuses on the use of the new technologies in the diffusion and teaching of the Portuguese Sign Language, the goal is to construct an improved graphical environment for transcription, 3-D graphics display and translate portuguese alphabetical to portuguese sign language, combining computer technology and linguistics research to...

  14. Abecedário 3D

    Deusdado, Leonel
    O artigo apresentado debruça-se sobre a utilização das novas tecnologias para divulgação e ensino da língua gestual. Embora exista um consenso sobre a necessidade de intervenção humana no ensino de uma língua gestual, também é verdade que não há contestação em relação ao valor acrescentado que as novas tecnologias representam como material complementar desse ensino. É dado um especial ênfase às tecnologias que utilizam imagens sintetizadas e/ou modelos baseados em gráficos tridimensionais para produzir e disponibilizar na Web um abecedário 3D em Língua Gestual Portuguesa.

  15. Influence of domain-specific notation to program understanding

    Kosar, Tomaz; Mernik, Marjan; Crepinsek, Matej; Henriques, Pedro; Cruz, Daniela; Pereira, Maria João; Oliveira, Nuno
    Application libraries are the most commonly used implementation approach to solve problems in general-purpose languages. Their competitors are domain-specific languages, which can provide notation close to the problem domain. We carried out an empirical study on comparing domain-specific languages and application libraries regarding program understanding. In this paper, one case study is presented. Over 3000 lines of code were studied and more than 86 pages long questionnaires were answered by end-users, answering questions on learning, perceiving and evolving programs written in domain specific language as well as general-purpose language using application library. In this paper, we present comparison results on end-users’ correctness and...

  16. VisualLISA: visual programming environment for attribute grammars

    Oliveira, Nuno; Henriques, Pedro; Cruz, Daniela; Pereira, Maria João
    The benefits of using visual languages and graphical editors are well known. In some specific domain it is really crucial to program with graphical representations, icons, geometric objects, colors and so on. Nowadays it is possible to easily implement a visual language, constructing, automatically, visual editors for it. In this paper we want to emphasize how it is possible to easily specify a huge amount of complex information, associated with an attribute grammar, using graphical objects and a very intuitive modular approach. For that purpose we present a new visual language to specify attribute grammars (called VisualLISA) and we present also a...

  17. Applying program comprehension techniques to Karel robot programs

    Oliveira, Nuno; Henriques, Pedro; Cruz, Daniela; Pereira, Maria João; Mernik, Marjan; Kosar, Tomaz; Crepinsek, Matej
    Abstract—In the context of program understanding, a challenge research topic1 is to learn how techniques and tools for the comprehension of General-Purpose Languages (GPLs) can be used or adjusted to the understanding of Domain-Specific Languages (DSLs). Being DSLs tailored for the description of problems within a specific domain, it becomes easier to improve these tools with specific visualizations (at a higher abstraction level, closer to the problem level) in order to understand the DSLs programs. In this paper, comprehension techniques will be applied to Karel language. This will allow us to explore the creation of problem domain visualizations for this language and to...

  18. Instrumentaciones de programas escritos en C para interrelacionar las vistas comportamental y operacional de los sistemas de software

    Berón, Mario; Henriques, Pedro; Pereira, Maria João; Uzal, Roberto
    La Comprensión de Programas es una disciplina de la Ingenier´ýa de Software cuyo principal objetivo es simplificar la comprensión de los sistemas de software. Una forma de alcanzar esta finalidad consiste en el desarrollo de estrategias de comprensión que permitan relacionar el Dominio del Problema, es decir el comportamiento del sistema, con el Dominio del Programa, o sea las construcciones del lenguaje de programacion utilizadas en la implementación del programa. La creación de este tipo de estrategias requiere de la: i) Definición de representaciones de los Dominios del Problema y Programa; ii) Elaboración de un procedimiento que vincule ambas representaciones y iii)...

  19. Comparison of XAML and C# frorms using cognitive dimensions framework

    Mernik, Marjan; Kosar, Tomaz; Crepinsek, Matej; Henriques, Pedro; Cruz, Daniela; Pereira, Maria João; Oliveira, Nuno
    Many domain-specific languages arise in the past years, trying to bring feasible alternatives for existing solutions with purpose to simplify programmers work. Although these little languages seem to be easier to use, there is an open issue whether they bring advantages comparing to most commonly used implementation approach, application libraries. In this work we present an experiment, carried out to compare such domain-specific language with comparable application library. The experiment was conducted with 36 programmers, which were answering questions on more than 100 long pages on both implementation approaches. For domain-specific language and application library the same problem domain has been used...

  20. VisualLISA: a domain specific visual language for attribute grammars

    Oliveira, Nuno; Pereira, Maria João; Henriques, Pedro; Cruz, Daniela
    The focus of this paper is on the translation of AG formalisms into a new visual language, and on the development of the associated programming environment. We present a solution for rapid development of VisualLISA editor using DEViL . This tool uses traditional attribute grammars, to specify the language’s syntax and semantics, extended by visual representations to be associated with grammar symbols. From these specifications a visual programming environment is automatically generated. This environment allows us to edit a visual description of an AG that is automatically translated into textual notations. In this paper, we emphasize the design and implementation of VisualLISA that...

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