Electrical and Electronic Engineering - Research Publications

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    Least-square Fitting on the Circle using Optimal Control
    Liu, C ; Suvorova, S ; Evans, RJ ; Moran, W ; Melatos, A (Elsevier BV, 2023-07-01)
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    Estimating and detecting random processes on the unit circle
    Liu, C ; Suvorova, S ; Evans, RJ ; Moran, W ; Melatos, A (Elsevier BV, 2023-01-01)
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    Detection and Estimation of Randomly Phase Modulated Signals
    Liu, C ; Suvorova, S ; Evans, RJ ; Moran, B ; Melatos, A (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2023)
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    Frequency Permutations for Joint Radar and Communications
    Senanayake, R ; Smith, PJ ; Han, T ; Evans, J ; Moran, W ; Evans, R (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2022-11)
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    Combined Radar and Communications With Phase-Modulated Frequency Permutations
    Han, T ; Senanayake, R ; Smith, P ; Evans, J ; Moran, W ; Evans, R (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2023)
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    Systematic upper limits on the size of missing pulsar glitches in the first UTMOST open data release
    Dunn, L ; Melatos, A ; Suvorova, S ; Moran, W ; Evans, RJ ; Oslowski, S ; Lower, ME ; Bailes, M ; Flynn, C ; Gupta, V (OXFORD UNIV PRESS, 2022-03-22)
    ABSTRACT A systematic, semi-automated search for pulsar glitches in the first UTMOST public data release is presented. The search is carried out using a hidden Markov model which incorporates both glitches and timing noise into the model of the assumed phase evolution of the pulsar. Glitches are detected through Bayesian model selection between models with and without glitches present with minimal human intervention. Nine glitches are detected among seven objects, all of which have been previously reported. No new glitches were detected. Injection studies are used to place 90 per cent frequentist upper limits on the size of undetected glitches in each of the 282 objects searched. The mean upper limit obtained is $\Delta f^{90{{\%}}}/f = 1.9 \times 10^{-8}$, with a range of $4.1 \times 10^{-11} \le \Delta f^{90{{\%}}}/f \le 2.7 \times 10^{-7}$, assuming step events with no post-glitch recoveries. It is demonstrated that including glitch recovery has a mild effect, in most cases increasing the upper limit by a factor of ≲5 conservatively assuming complete recovery on a time-scale of $100\ \mathrm{d}$.
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    Bayesian Detection of a Sinusoidal Signal With Randomly Varying Frequency
    Liu, C ; Suvorova, S ; Evans, RJ ; Moran, B ; Melatos, A (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2022)
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    Testing for a Random Walk Structure in the Frequency Evolution of a Tone in Noise
    Abramson, S ; Moran, W ; Evans, R ; Melatos, A (MDPI, 2022-08)
    Inference and hypothesis testing are typically constructed on the basis that a specific model holds for the data. To determine the veracity of conclusions drawn from such data analyses, one must be able to identify the presence of the assumed structure within the data. In this paper, a model verification test is developed for the presence of a random walk-like structure in the variations in the frequency of complex-valued sinusoidal signals measured in additive Gaussian noise. This test evaluates the joint inference of the random walk hypothesis tests found in economics literature that seek random walk behaviours in time series data, with an additional test to account for how the random walk behaves in frequency space.
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    On the use of switched linear controllers for stabilizability of implicit recursive equations
    Nesic, D (IEEE, 1998-01-01)
    Stabilizability of implicit recursive equations is investigated. These equations arise naturally in the context of output dead-beat control for systems described by NARMAX models. Due to non-uniqueness of the solutions of these equations a special kind of a constrained stabilizability problem is considered. We take a hybrid switching control approach in testing the existence of a locally stabilizing controller. A method for the design of a stabilizing switching controller is also presented.
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    Analysis of minimum phase properties for non-affine nonlinear systems
    Nesic, D ; Skafidas, E ; Mareels, IMY ; Evans, RJ (IEEE, 1997)
    A system can be termed non-minimum phase according to some definitions available in the literature and yet the same system may exhibit stable zero output constrained dynamics. We show that for non-affine nonlinear systems there may not exist a continuous control law which would keep the output identically equal to zero and for which the zero output constrained dynamics are stable, whereas a discontinuous controller which achieves this exists. We give conditions for existence and present a method for design of discontinuous switching controllers which yield stable zero dynamics. In this sense, the results of this paper enlarge the class of non-affine nonlinear systems that can be termed minimum-phase.