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Publicações

2000

Mixed-signal BIST using correlation and reconfigurable hardware

Autores
Machado Da Silva, J; Duarte, JS; Matos, JS;

Publicação
Proceedings -Design, Automation and Test in Europe, DATE

Abstract
Reducing the area overhead required by BIST structures can be achieved by reconfiguring existing hardware to perform test related control and processing functions. This work shows how the resources required for these operations can be implemented in-circuit, taking advantage of programmable logic available in the system. Structural and functional tests are performed using correlation to obtain iDD and uOUT cross-correlation signatures, and to measure gain, phase, and total harmonic distortion. © 2000 IEEE.

2000

A real time approach to identify actions to prevent voltage collapse using Genetic Algorithms and Neural Networks

Autores
Ferreira, JR; Lopes, JAP; Saraiva, JT;

Publicação
2000 IEEE POWER ENGINEERING SOCIETY SUMMER MEETING, CONFERENCE PROCEEDINGS, VOLS 1-4

Abstract
In this paper we describe a new approach to identify the combination of tap transformer positions, capacitor bank steps together with the minimum amount of toad to be shed that assures one to obtain a specified security degree of a power system. The basic approach is designed to identify the most adequate actions to be taken for a given contingency. This identification procedure uses Genetic Algorithms given their adequacy to model discrete actions. However, Genetic Algorithms are known for their usually large computation time. In order to address this issue and having in mind the objective of developing a real time tool, we incorporated a classification procedure based on Neural Networks. The paper includes results obtained using the developed approach both to evaluate the quality of the solutions for a number of contingencies and the quality of the overall performance when using the Neural Network tool. Results obtained for a reduced version of the Brazilian Mate Grosso transmission system are presented and discussed.

2000

A Web browser based DMS - Distribution Management System

Autores
Silva, MP; Saraiva, JT; Sousa, AV;

Publicação
2000 IEEE POWER ENGINEERING SOCIETY SUMMER MEETING, CONFERENCE PROCEEDINGS, VOLS 1-4

Abstract
In this paper we describe an application corresponding to a DMS system - Distribution Management System - that is organized in terms of a distributed multitask client-server architecture. The system is implemented according to the Object Oriented paradigm leading to a number of objects related with electric devices and specific algorithms. At this level of development, these algorithms correspond to topology processor, state estimation, power flow and short circuit analysis. They correspond to main coordinator objects that can be achieved by clients of the system in terms of Java applets running within a WEB browser. fn the paper we detail the structure of the system and describe some objects and applications.

2000

Components as processes: An exercise in coalgebraic modeling

Autores
Barbosa, LS;

Publicação
FORMAL METHODS FOR OPEN OBJECT-BASED DISTRIBUTED SYSTEMS IV

Abstract
Software components, arising, typically, in systems' analysis and design, are characterized by a public interface and a private encapsulated state. They persist (and evolve) in time, according to some behavioural patterns. This paper is an exercise in modeling such components as coalgebras for some kinds of endo-functors on Set, capturing both (interface) types and behavioural aspects. The construction of component categories, cofibred over the interface space, emerges by generalizing the usual notion of a coalgebra morphism. A collection of composition operators as well as a generic notion of bisimilarity, are discussed.

2000

Data driven underwater transient detection based on time-frequency distributions

Autores
Oliveira, PM; Barroso, V;

Publicação
OCEANS 2000 MTS/IEEE - WHERE MARINE SCIENCE AND TECHNOLOGY MEET, VOLS 1-3, CONFERENCE PROCEEDINGS

Abstract
The complexity of real-life transients, coupled with the incomplete (or absent) knowledge of their statistical structure or defining features has motivated the interest on the use of blind, data driven detection schemes. One such scheme, proposed by Jones and Sayeed, uses Time-Frequency distributions to implement sub-optimal quadratic detectors which, under certain conditions, approach the performance of optimal quadratic detectors. However, their use of Fisher's discriminants to obtain class separation has some drawbacks, which we solve by using a simple perceptron to obtain the discriminant. Also, more often than not, we will have a multiclass situation, implying the use of different Time-Frequency Distributions, each one of them tuned for a given class of transients. The different nature of these distributions (bias, type of cross-terms, time-frequency resolution, etc.) will hamper the performance of the algorithm, forcing the need for experimental validation of its heuristical aspects. These are the issues we will address. The algorithm will be applied to real data, and its performance investigated.

2000

Agents working on the integration of heterogeneous information sources in distributed healthcare environments

Autores
Oliveira, IC; Belo, O; Cunha, JP;

Publicação
ADVANCES IN ARTIFICIAL INTELLIGENCE

Abstract
Hospital information infrastructures integrate today complex mosaics of heterogeneous systems, often dependent on legacy systems. The integration of disparate information sources in healthcare is an essential effort since physicians, and other hospital personnel, use to analyze and combine data provided by different sources distributed along the hospital facilities. Day-after-day their needs for effective means and tools to support such integration of data increase significantly. In order to fulfill such requirements we designed and developed an extensible multi-agent system that physicians may use to access multiple medical data sources available at the hospital, in a transparent way. This paper presents an overall description of the system giving special attention to its architecture and community of software agents. The agents were specially planned for clinical information gathering, cleaning, integration and presentation in healthcare environments.

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