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Software construction for mathematical applications

Silva, Miguel Oliveira e; Vaz, Francisco

This paper studies the problem of software construction for mathematical applications, and proposes a different structuring technique following the Object-Oriented paradigm. A short study about the “classic” functional structure used in this area is made, pointing out its qualities and drawbacks. An Object-Oriented analysis and design is performed, and from it is enumerated a set of requirements to impose on pr...


User interface for a decision support system based on factor analysis

Carvalhal, Carlos Rui; Santos, Beatriz Sousa; Ferreira, Carlos; Rafael, José Alberto

A Decision Support System based on Factor Analysis was designed to offer the user the possibility to perform easily four types of Factor Analysis: Principal Component, Discriminant, Correspondence and Distance. We will describe the user interface of such a system, developed for Windows using Visual Basic TM 3.0.; Neste artigo descreve-se o interface de utilizador de um Sistema de Apoio à Decisão baseado em...


Dynamic neural model for categorical perception of speech

Bicho, Estela; Schoner, Gregor; Vaz, Francisco

The phenomenon of categorical perception has played an enormous role in the theory of speech perception. One reason is that categorical perception is at the interfacebetween the analog sensory signal and the discrete andsimbolic nature of language. Another phenomenon involvedin speech perception is selective adaptation. Adaptationeffects appear with respect to the location of the categoricalboundary along a spe...


Application of structured methods in the specification and implementation of a ...

Santos, José P.; Ramos, Fernando M. S.

In 1990 INESC (Institute of System Engineering and Computers) was contracted hy PT-Portugal Telecom -the Portuguese telecom operator - to develop the prototype ofa telesurveilling system supported on ISDN (IntegratedServices Digital Network), in the context of the R&Dactivities promoted hy PT concerning the introduction ofISDN in Portugal, project that was concluded in 1994. Thispaper includes a hrief surve...


Portuguese participation in the RACE TeleCommunity Project

Rocha, Nelson Pacheco da; Afonso, Ernesto; Breda, Pedro; Machado, Manuel; Pereira, Leonor Moniz; Cidade, Clara

The TeleCommunity project in the context of RACE program is a set of Advanced Communications Experiments that aim to study the implementation of advanced communications services for disabled people. The paper presents the support services and the terminal equipment developed for the Portuguese experiment within the TeleCommunity Project. The services (Learning and Training, Remote Delivery ofExpertise, Collabor...


Ethernet traffic measurements: a case study

Oliveira, José Luís; Martins, Joaquim Arnaldo; Pinto, Joaquim Sousa

Local Area Networks have been spread over the world during the last decade with an increasing installation rate. The expansion of each LAN, caused the introduction of new systems, usually implies more network traffic. It's important to the network manager to know the characteristics of this traffic in order to study, by simulation, the expected grow on data interchange and to plan future redesign of the network...


Linearization of power amplifiers for active feedback

Pedro, José Carlos; Perez, Jorge; Pereira, José Rocha

This paper describes the work developed under thePh.D. course of its author [I]. It is devided in four main partswhich refer to the motivation, theoretical background ofamplifier linearization circuits design, GaAs MESFETmodeling, and finally, experimental validation. That wasacheived by the design and test of a MMIC power amplifier, linearized by means of active feedback.; O trabalho que neste artigo se descre...


Determination of brain activity maps from a band of frequencies

Barreto, Carlos Loff; Vaz, Francisco

In this paper we present a new method to compute brain maps. It is based on the power estimation of the filtered signal on a11 channels which is faster to compute than the traditional aproach using DFT. Reducing the time needed for computation we can have a better dynamic display of the evolution of the brain potentials on the scalp.; Apresenta-se neste trabalho um novo método para a determinação de mapas ...


Digital image processing package in Microsoft WINDOWS environment

Godinho, Anabela; Santos, Osvaldo; Pereira, A. Sousa

The goal of this paper is to describe a generic Digital Image Processing Package in Microsoft WINDOWS environment. Several tecniques are used, such as Image Transforms ( Fourier, Walsh, Hadamard ), Histogram processing, Spatial Filtering and Color Map processing. An automatic character recognition tecnique isalso described.; Este artigo descreve um sistema genérico de Processamento Digital de Imagem em amb...


A low cost and high linearity receiver's for Cable TV Systems to the Home (FTTH)

Domingues, Paulo Grilo; Pedro, José Carlos

A receiver circuit for use in Fiber to the Home (FTTH) Cable TV Systems is presented. The design is based on low cost small signal GaAs FET devices and proposes a new scheme for the reduction of the 2nd order non-linear distortion generated by the active devices.; É apresentado um circuito para utilização em receptores de Televisão por Cabo Óptico até ao assinante (FTTH). A arquitectura é baseada em d...


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