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Limited By:	Subject = Spectral analysis;

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Displaying Results 1 - 5 of 5 on page 1 of 1

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Application of non-linear analysis techniques to sigma-delta modulators (1997)

Farrell, Ronan; Feely, Orla

Application of non-linear analysis techniques to sigma-delta modulators (1997)

Farrell, Ronan; Feely, Orla

Abstract:

In the past sigma-delta modulators have been analysed using linear analysis techniques. In these approaches the quantiser is replaced by an additive white noise source and then standard linear systems analysis is applied. This approach can provide good estimates of noise performance but it is unable to explain much of the behaviour of sigma-delta modulators, especially such phenomena as instability, integrator spans, quantiser switching frequency, idle tones, strong limit cycle behaviour and chaos, which are inherently non-linear. To examine these problems it will be necessary to utilise some of the many non-linear analysis techniques now available. A full rigorous non-linear analysis of these systems using any one technique would be very difficult, if not impossible. An alternative is to identify specific problems, such as instability, and to apply the most suitable non-linear analysis technique to the problem. Three main approaches have been applied to the non-linear analysis of s...

http://mural.maynoothuniversity.ie/9754/

Marked Mark

Convolutive non-negative matrix factorisation with a sparseness constraint (2006)

Pearlmutter, Barak A.; O'Grady, Paul D.

Convolutive non-negative matrix factorisation with a sparseness constraint (2006)

Pearlmutter, Barak A.; O'Grady, Paul D.

Abstract:

Discovering a representation which allows auditory data to be parsimoniously represented is useful for many machine learning and signal processing tasks. Such a representation can be constructed by non-negative matrix factorisation (NMF), a method for finding parts-based representations of non-negative data. We present an extension to NMF that is convolutive and includes a sparseness constraint. In combination with a spectral magnitude transform, this method discovers auditory objects and their associated sparse activation patterns.

http://mural.maynoothuniversity.ie/1375/

Marked Mark

Experimental Determination of the Hydrodynamic Parameters of an OWC (2017)

Kelly, Thomas; Dooley, Thomas; Ringwood, John

Experimental Determination of the Hydrodynamic Parameters of an OWC (2017)

Kelly, Thomas; Dooley, Thomas; Ringwood, John

Abstract:

A novel technique to measure the frequency-dependent hydrodynamic parameters of an oscillating water column (OWC) using tank testing is proposed. This technique arose from investigations into the effect on the power absorbed by OWCs of air compressibility in the chamber above the water column. Two models of an OWC were constructed for that investigation. For the first model, the volume of the air chamber above the water column was scaled geometrically by the factor to which the water column was scaled. For the second, the volume of the air chamber was scaled by the square of the factor to which the water column was scaled. The proposed technique to measure the hydrodynamic parameters,which eliminates the need for a forced-oscillation rig, uses these two OWC models, and relies on water column motion which takes place due to air compression when the air chamber of the second model is seale...

http://mural.maynoothuniversity.ie/12459/

Marked Mark

Predictor Design for Altitude Control of a Seaweed Harvester (2010)

Galllieri, Marco; Ringwood, John; Giantomassi, Andrea; Ippoliti, Gianluca; Longhi, Sauro

Predictor Design for Altitude Control of a Seaweed Harvester (2010)

Galllieri, Marco; Ringwood, John; Giantomassi, Andrea; Ippoliti, Gianluca; Longhi, Sauro

Abstract:

In this paper, the predictor design, for altitude control of a seaweed harvester, is investigated. The harvesting system consists of a vessel and a suspended harvester device, the altitude of which is controlled by a winch. The control approach of Gallieri and Ringwood (2010), including a feedforward action, which requires a single step disturbance prediction, is investigated further, focusing on the disturbance prediction, for noisy sensors. The prediction is performed using AR and ARMA models, identified online, by using the Recursive Least Squared with Forgetting Factor (RLSFF) algorithm and the Kalman Filter (KF). The dependance between the error spectrum and the quality of the control is shown, and the prediction performances are evaluated, using an FFT-based criterion, oriented to the feedforward application. The control performances are then evaluated, and the results are compared to Gallieri and Ringwood (2010).

http://mural.maynoothuniversity.ie/3609/

Marked Mark

Sinusoids, noise and transients: spectral analysis, feature detection and real-time transformations of audio signals for musical applications (2012)

Glover, John C.

Sinusoids, noise and transients: spectral analysis, feature detection and real-time transformations of audio signals for musical applications (2012)

Glover, John C.

Abstract:

This thesis examines the possibilities for real-time transformations of musical audio signals using sinusoidal models. Four open-source software libraries were developed with the goal of providing real-time spectral synthesis by analysis tools for composers, musicians, researchers and audio signal processing developers. The first of these, called Simpl, provides a consistent API for interacting with established sinusoidal modelling systems from the literature, and integrates seamlessly with a powerful suite of libraries for scientific computing. Sinusoidal models have been used to transform slowly-varying quasi-harmonic signals with much success, but they have well-documented weaknesses in dealing with transient signal regions. This problem is significant, as in monophonic musical sounds, transient locations often correspond with the attack section of notes and this region plays a large part in our perception of timbre. However in order to improve the synthesis of note attack transi...

http://mural.maynoothuniversity.ie/4523/

Displaying Results 1 - 5 of 5 on page 1 of 1