Browsing by Author "Nocetti, D. F. G."
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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.
- 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.
- High performance parallel-DSP computing in model-based spectral estimationPublication . Gonzalez, J. S.; Nocetti, D. F. G.; Ruano, M. GraçaDoppler blood flow spectral estimation is a technique for non-invasive cardiovascular disease detection. Blood flow velocity and disturbance may be determined by measuring the spectral mean frequency and bandwidth, respectively. The work presented here, evaluates a high performance parallel-Doppler Signal Processing architecture (SHARC) for the computation of a parametric model-based spectral estimation method known as the modified covariance algorithm. The model-based method incorporates improvement in frequency resolution when compared with Fast Fourier Transform (FFT)-based methods. However, the computational complexity and the need for real-time response of the algorithm, makes necessary the use of high performance processing in order to fulfil such demands. Sequential and parallel implementations of the algorithm are introduced, A performance analysis of the implementations is also presented, demonstrating the effectiveness of the algorithm and the feasibility for real-time response of the system. The results open a greater scope for utilising this architecture in implementing new and more complex methods. The results are applied to the development of a real-time spectrum analyser for pulsed Doppler blood flow instrumentation. (C) 1999 Elsevier Science B.V. All rights reserved.
- High-performance computing for real-time spectral estimationPublication . Madeira, M. M.; Bellis, S. J.; Beltran, L. A. A.; Gonzalez, J. S.; Nocetti, D. F. G.; Marnane, W. P.; Tokhi, M. O.; Ruano, M. GraçaThis paper presents two separate investigations into the real-time implementation of the modified covariance spectral estimator: one comparing performances on digital signal processors, the TMS320C40, and the recently released ADSP2016x (SHARC); another using application-specific custom circuitry. The advantages and disadvantages of each of these different approaches are reviewed, resulting in the design of a field-programmable gate array/digital signal processor-based high-performance system that combines the hardware and software approaches. In conjunction with pulsed Doppler ultrasound blood-flow detectors, the spectral estimator offers increased sensitivity in the non-invasive detection of arterial disease. (C) 1999 Elsevier Science Ltd. All rights reserved.
- Solving practical issues of a portable Doppler ultrasound system for blood flow assessment during coronary graft surgeryPublication . Zabihian, B.; Ruano, M. Graça; Gonzalez, J. S.; Nocetti, D. F. G.; Cruz, M. F.This paper presents some practical issues regarding the development of a dedicated Doppler Ultrasound system (DUS) for the assessment of blood flow signal on coronary grafts during heart surgery. The DUS is composed of several processing units. This paper concentrates on front-end units: the transducer and a particular issue of the software interface for clinical evaluation, the noise cancellation technique (NCTech). The experimental set-up implemented to evaluate the transducer response is presented. The procedure employed to eliminate the noise components embedded in the DUS data is described. Each of these units was primarily tested in laboratory. Results show their effectiveness in achieving their specific goals. Comments on the overall system's performance are presented denoting the usefulness of such dedicated DUS during bypass assessment at heart surgery. © 2011 IEEE.