Browsing by Author "Fleming, P. J."
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- A spectral estimator using parallel-processing for use in a doppler blood-flow instrumentPublication . Ruano, M. Graça; Nocetti, D. F. G.; Fish, P. J.; Fleming, P. J.The work described here is part of a research program aiming to increase the sensitivity to disease detection using Doppler ultrasound by reducing the effects to the measurement procedure on the estimation of blood velocity and detection of flow disturbance.
- Accelerating multi-objective control system design using a neuro-genetic approachPublication . Duarte, N. M.; Ruano, Antonio; Fonseca, C. M.; Fleming, P. J.Designing control systems using multiobjective genetic algorithms can lead to a substantial computational load as a result of the repeated evaluation of the multiple objectives and the population-based nature of the search. Here, a neural network approach, based on radial basis functions, is introduced to alleviate this problem by providing computationally inexpensive estimates of objective values during the search. A straightforward example demonstrates the utility of the approach.
- Alternative parallel implementations of an AR-modified covariance spectral estimator for diagnostic ultrasonic blood flow studiesPublication . Ruano, M. Graça; Nocetti, D. F. G.; Fish, P. J.; Fleming, P. J.The work described here is part of a research program aiming to increase the sensitivity to desease detection using Doppler ultrasound by reducing the effects of the measurement procedure on the estimation of blood velocity and detection of flow disturbance. The paper presents a summary of autoregressive spectral estimation, focusing the attention on a specific estimator - the modified covariance method. This method has been realized in parallel to achieve a fast computer processing. The new parallel version of this algorithm has been developed and implemented on a multiprocessing transputer-based system. Two different approaches to the problem of parallel partitioning the algorithm into a number of tasks were considered - a fine and a medium grain task scheme. The medium grain scheme is mapped onto a transputer-based system, by means of a processor farm computational structure. Two approaches to this farm model were adopted: a linear and a tree topology. For different model parameters, performance measurements were obtained revealing that the tree topology offers a higher performance. © 1993.
- An efficient parallel implementation of a least squares problemPublication . Ruano, Antonio; Fleming, P. J.; Jones, D. I.Least squares solutions are a very important problem, which appear in a broad range of disciplines (for instance, control systems, statistics, signal processing). Our interest in this kind of problems lies in their use of training neural network controllers.
- An efficient parallel implementation of a least squares problemPublication . Ruano, Antonio; Fleming, P. J.; Jones, D. I.Least squares solutions are a very important problem, which appear in a broad range of disciplines (for instance, control systems, statistics, signal processing). Our interest in this kind of problems lies in their use of training neural network controllers.
- Automatic tuning of PID controllers using a neuro-genetic systemPublication . Ruano, Antonio; Lima, João; Azevedo, Ana Beatriz da Piedade de; Duarte, N. M.; Fleming, P. J.Neural networks and genetic algorithms have been in the past successfully applied, separately, to controller turning problems. In this paper we propose to combine its joint use, by exploiting the nonlinear mapping capabilites of neural networks to model objective functions, and to use them to supply their values to a genetic algorithm which performs on-line minimization.
- Comparison of alternative approaches to neural network PID autotuningPublication . Ruano, Antonio; Lima, João; Mamat, R.; Fleming, P. J.In this paper, a scheme for the automatic tuning of PID controllers on-line, with the assistance of trained neural networks, is proposed. The alternative approaches are presented and compared.
- Connectionist approach to PID autotuningPublication . Ruano, Antonio; Fleming, P. J.; Jones, D. I.Proportional, Integral and Derivative (PID) regulators are standard building blocks for industrial automation. The popularity of these regulatores comes from their rebust performance in a wide range of operationg conditions, and also from their functional simplicity, which makes them suitable for manual tuning.
- A connectionist approach to PID autotuningPublication . Ruano, Antonio; Fleming, P. J.; Jones, D. I.Proportional, Integral and Derivative (PID) regulators are standard building blocks for industrial automation. The popularity of these regulators comes from their rebust performance in a wide range of operating conditions, and also from their functional simplicity, which makes them suitable for manual tuning.
- Identification of aircraft gas-turbine dynamics using B-splines neural networksPublication . Lopes, J. C.; Ruano, Antonio; Fleming, P. J.This paper describes preliminary results regarding the development of a B-splines neural network model of the fuel feed to shaft-speed dynamics of a twin-shaft gas turbine engine. Data recorded from practical testing of the turbine to a multisine input were employed, and models were identified at different points along the turbine operating curve. B-splines neural networks have been found to be good models of the system, delivering good results especially for long-range predictions.
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