Browsing Doctoral Degrees (Electrical and Electronic Engineering) by Title
Now showing items 57-76 of 139
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Efficient Decoding of High-order Hidden Markov Models
(Stellenbosch : University of Stellenbosch, 2007-12)Most speech recognition and language identification engines are based on hidden Markov models (HMMs). Higher-order HMMs are known to be more powerful than first-order HMMs, but have not been widely used because of their ... -
Efficient finite element electromagnetic analysis of antennas and microwave devices : the FE-BI-FMM formulation and a posteriori error estimation for p adaptive analysis
(Stellenbosch : Stellenbosch University, 2002-09)ENGLISH ABSTRACT: This document presents a Galerkin FE formulation for the full-wave, frequency domain, electromagnetic analysis of three dimensional structures relevant to microwave engineering, together with the ... -
Efficient high-order time domain finite element methods in electromagnetics
(Stellenbosch : University of Stellenbosch, 2009-03)The Finite Element Method (FEM) as applied to Computational Electromagnetics (CEM), can beused to solve a large class of Electromagnetics problems with high accuracy and good computational efficiency. For solving wide-band ... -
Efficient Mixed-Order Hidden Markov Model Inference
(Stellenbosch : University of Stellenbosch, 2007-12)Higher-order Markov models are more powerful than first-order models, but suffer from an exponential increase in model parameters with order, which leads to data scarcity problems during training. A more efficient ... -
Efficient numerical analysis of finite antenna arrays using domain decomposition methods
(Stellenbosch : Stellenbosch University, 2014-12)ENGLISH ABSTRACT: This work considers the efficient numerical analysis of large, aperiodic finite antenna arrays. A Method of Moments (MoM) based domain decomposition technique called the Domain Green's Function Method ... -
Empirical state space modelling with application in online diagnosis of multivariate non-linear dynamic systems
(Stellenbosch : Stellenbosch University, 1999-12)ENGLISH ABSTRACT: System identification has been sufficiently formalized for linear systems, but not for empirical identification of non-linear, multivariate dynamic systems. Therefore this dissertation formalizes and ... -
Estimating the Pen Trajectories of Static Handwritten Scripts using Hidden Markov Models
(Stellenbosch : University of Stellenbosch, 2005-12)Individuals can be identified by their handwriting. Signatures are, for example, currently used as a biometric identifier on documents such as cheques. Handwriting recognition is also applied to the recognition of ... -
Evaluation and design aspects of magnetic gears and magnetically geared electrical machines
(Stellenbosch : Stellenbosch University, 2015-12)ENGLISH ABSTRACT: In the past decade, magnetic gears and magnetically geared electrical machines have emerged as electromechanical devices with exceptionally high torque densities. Their distinct advantages such as low ... -
An experimental study of artificial isotropic chiral media at microwave frequencies
(Stellenbosch : Stellenbosch University, 1994-12)ENGLISH ABSTRACT: An artificial chiral medium can be made by embedding metal helices (chiral or handed structures) with random orientation inside au achiral hnst medium. The electromagnetic behaviour of such artificial ... -
Fabrication of Josephson junctions using AFM nanolithography
(Stellenbosch : University of Stellenbosch, 2010-12)ENGLISH ABSTRACT: Planar weak link structures, such as micro-bridges, variable thickness bridges and nanobridges, have always attracted a lot of attention. Their potential to behave as real Josephson elements make them ... -
Fast Mesh-based physical optics for large-scale electromagnetic analysis
(Stellenbosch : Stellenbosch University, 2016-12)ENGLISH ABSTRACT: At sufficiently high frequencies, the electrical size of scattering objects become very large. The electromagnetic field simulation of such objects becomes prohibitively expensive with physically rigorous ... -
Fast multi-core CEM solvers and flux trapping analysis for superconducting structures
(Stellenbosch : Stellenbosch University, 2018-03)ENGLISH ABSTRACT: The dissertation presents the development of a numerical field solver, called TetraHenry (TTH), for inductance extraction and flux trapping analysis of superconducting integrated circuits. The solver ... -
A Fixed Switching Frequency technique for finite-set model predictive control of power electronic converters
(Stellenbosch : Stellenbosch University, 2016-03)ENGLISH ABSTRACT: A fixed switching frequency scheme for finite-control-set model predictive control is resented. The purpose of the control scheme is to achieve an output waveform quality that compares well to that of a ... -
A framework and criteria for the operability of unmanned aircraft systems
(Stellenbosch : University of StellenboschDrone aircraftAirplanes -- Radio control, 2010-12)ENGLISH ABSTRACT: Airworthiness certification of unmanned aircraft systems (UAS) is normally considered to be a regulatory function. In the absence of comprehensive UAS airworthiness regulations, the development of new ... -
From high-speed superconducting devices to nanosensors
(Stellenbosch : Stellenbosch University, 2017-03)ENGLISH ABSTRACT: In this dissertation the story of a research career spanning 34 years is told. It started in microelectronics in the early 1980’s and focused on aspects of design and optimization of high-voltage diodes. ... -
GPU acceleration of matrix-based methods in computational electromagnetics
(Stellenbosch : University of Stellenbosch, 2011-03)ENGLISH ABSTRACT: This work considers the acceleration of matrix-based computational electromagnetic (CEM) techniques using graphics processing units (GPUs). These massively parallel processors have gained much support ... -
Growth-based computer aided design strategies for multimode waveguide design with the aid of functional blocks
(Stellenbosch : Stellenbosch University, 2001-12)ENGLISH ABSTRACT: A new technique for the design of multimode devices in overmoded waveguide is presented. The technique applies the principle of growth-based design and uses a conceptual functional block representation ... -
Hardware description language modelling and synthesis of superconducting digital circuits
(Stellenbosch : Stellenbosch University, 2017-03)ENGLISH ABSTRACT: The energy demands and computational speed in high performance computers threatens the smooth transition from petascale to exascale systems. Miniaturization has been the art used in CMOS (complementary ... -
Improving the direction-dependent gain calibration of reflector antenna radio telescopes
(Stellenbosch : Stellenbosch University, 2013-12)ENGLISH ABSTRACT: Utilising future radio interferometer arrays, such as the Square Kilometre Array (SKA), to their full potential will require calibrating for various direction- dependent effects, including the radiation ... -
Interpolation-based modelling of microwave ring resonators
(Stellenbosch : University of Stellenbosch, 2006-12)Resonant frequencies and Q-factors of microwave ring resonators are predicted using interpolation- based modelling. A robust and efficient multivariate adaptive rational-multinomial combination interpolant is presented. ...
