Stephen J. Weddell

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This study investigates the classification ability of linear and nonlinear classifiers on biological signals using the electroencephalogram (EEG) and examines the impact of architectural changes within the classifier in order to enhance the classification. Consequently, artificial events were used to validate a prototype EEG-based microsleep detection(More)
The performance of a microsleep detection system was calculated in terms of its ability to detect the behavioural microsleep state (1-s epochs) from spectral features derived from 16-channel EEG sampled at 256 Hz. Best performance from a single classifier model was achieved using leaky integrator neurons on an echo state network (ESN) classifier with a mean(More)
Brief episodes of momentarily falling asleep - microsleeps - can have fatal consequences, especially in the transportation sector. In this study, the EEG data of eight subjects, while performing a 1-D tracking task, were used to predict imminent microsleeps. A novel algorithm was developed to improve the accuracy of microsleep identification from two(More)
A new method is presented which provides prediction of the spatially variant point spread function for the restoration of astronomical images, distorted by atmospheric turbulence when viewed using ground-based telescopes. Our approach uses reservoir computing to firstly learn the spatio-temporal evolution of aberrations caused by turbulence, and secondly,(More)
The maximum subarray problem is used to identify the subarray of a two dimensional array, where the sum of elements is maximized. In terms of image processing, the solution has been used to find the brightest region within an image. Two parallel algorithms of the maximum subarray problem solve this problem in O(n) and O(log n) time. A field programmable(More)
Precise measurement of aberrations within an optical system is essential to mitigate combined effects of user-generated aberrations for the study of anisoplanatic imaging using optical test benches. The optical system point spread function (PSF) is first defined, and methods to minimize the effects of the optical system are discussed. User-derived(More)
Two methods of physiological gating, prospective and retrospective, have been investigated for the Medipix All-Resolution Systems (MARS) spectral CT scanner in order to reduce image blurring due to cardiovascular motion. The scanner is currently designed for scanning small animals, however there are plans to extend it to clinical applications in future.(More)
Motivation for this research is the real-time restoration of faint astronomical images through turbulence over a large field-of-view. A simulation platform was developed to predict the centroid of a science object, convolved through multiple perturbation fields, and projected on to an image plane. Centroid data were selected from various source and target(More)
Biosignal classification systems often have to deal with extraneous features, highly imbalanced datasets, and a low SNR. A robust feature selection/reduction method is a crucial step in this process. Sets of artificial data were generated to test a prototype EEG-based microsleep detection system, consisting of a combination of EEG and 2-s bursts of 15-Hz(More)