Faculty of Engineering and Built Environment
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Item A particle swarm optimization approach for model independent tuning of PID control loops(IEEE, 2007-09) Nelendran Pillay; Poobalan GovenderThe paper proposes a model independent tuning technique that yields optimal proportional-integral-derivative parameters for a range of typical process control loops. The proposed tuning technique utilizes the particle swarm optimization algorithm to generate optimal tuning parameters. The PSO tuning method is applied to typical process models. Comparisons are made between the proposed PSO technique and other conventional methods. ©2007 IEEE.Item PWM-VSI inverter-assisted stand-alone dual stator winding induction generator(Institute of Electrical and Electronics Engineers (IEEE), 2000-11) Ojo, Olorunfemi; Davidson, Innocent EweanThis paper presents a novel usage of a dual stator winding three-phase induction machine as a stand-alone generator with both controlled output load voltage magnitude and frequency. This generator, with both three-phase power and control windings housed in the stator structure, has the load connected to the power winding and a three-phase pulsewidth modulation (PWM) voltage-source inverter sourcing the control winding. The input to the PWM inverter is either a battery source or a charged dc capacitor. The operational characteristics of these generator schemes with either of the two inverter sources are investigated and shown to have desirable performance. How the load voltage magnitude depends on the various control and design parameters such as rotor speed, compensating capacitance, and load impedance is determined using a detailed mathematical model of the system.Item Evaluation and effective management of non-technical losses in power networks(2002-10) Davidson, Innocent EweanMarket-driven economies and deregulated electricity industry environment have stimulated the minimization of technical and non-technical losses (NTL) even though they do not constitute major operational or quality of supply problems. Their impact is economic and utilities often passed down the costs to consumers. NTL need to be addressed to determine the overall performance of power networks, as these losses are expected to be more dominant at the sub-transmission (132kV-33kV) and reticulation (22kV and 11kV) levels of the electricity supply industry value chain. In some national grid operations, NTL are estimated to account for up to 30% in revenue losses to electric utilities, and overhead expenditure in added maintenance costs. This paper discusses a method for NTL evaluation and an effective management approach to loss minimization and revenue collection. Copyright © 2002 IEEE.Item Performance analysis of a shaded-pole linear induction motor using symmetrical components, field analysis, and finite element method(Institute of Electrical and Electronics Engineers (IEEE), 2000-03) Davidson, Innocent Ewaen; Gieras, Jacek F.The application of symmetrical components of two-phase asymmetric systems, field theory, and finite element method (FEM) to the performance calculation of the shaded-pole linear induction motor (LIM) is presented. The results compared with measurements are satisfactory though the performance of the shaded-pole single-phase LIM is poor when compared to three-phase LIMs. LIMs generally have low efficiencies due to their open airgap. The maximum efficiency of rotary shaded-pole induction motors with cage-rotors rated at 100 W usually does not exceed 20%.Item An analysis of the factors influencing the relationship between soil properties and optimum moisture content and the formulation of an abbreviated test method of determinig maximum dry density(1997) Allinsin, Anthony James; Coetzee, J.The strength and durability of any soil structure is dependent on the quality of the compaction of the soil. This quality is measured by employing a standard compaction test, which provides a standard with which density may be compared, called the maximum dry density, and the moisture content of the soil at which this is achieved, called the optimum moisture content. As a matter of routine during quality control, the particle size distribution, plasticity index and liquid limit of the soil are determined at the same time as its maximum dry density and optimum moisture content.Item Methodologies for the optimal design of fibre-reinforced composite structures(2003) Smith, Ryan Elliot; Walker, MarkComposites have become important engineering materials, especially in the fields of automotive, aerospace and marine engineering. This is due to the high specific strength and stiffness properties they offer. At present, fibre-reinforced plastic (FRP) laminates are some of the most common types of composite used. They are produced in various forms with different structural properties. As with all engineering materials, there is the existence of both advantages and disadvantages. One of the main disadvantages is the expense involved in producing both the material and the finished product. The design time is also costly as the material has to be designed concurrently with the structure.Item Laboratory optimisation of the carbonatation process with regard to colour removal at the Malelane Refinery(2001) Moodley, Manogran; Lionnet, G. R. E.The purpose of this investigation was to identify and then optimise the factors that affect the decolourisation during the carbonatation process. Batch carbonatation tests, carried out in a pilot plant in the laboratory, were performed to establish the effect of selected factors on the decolourisation of melt.Item Cost effective electrical reticulation of the rural areas in Transkei at the district of Lady Frere (Nkolonga)(1995) Booi, Bongani Mpumelelo; Khumalo, J.The purpose of this study is to investigate the most cost effective way of electrifying rural areas in the Transkei concentrating in the district of Lady Frere. One Administrative Area (A.A) was used for research. Questionnaires were send to people of this area where a like rat format was followed. For the purpose of this study, 20 families were randomly selected for investigation.Item An investigation into the development of a portable, ultrasonic, density measuring instrument(1987) Hulse, Nigel Douglas; Stewart, A. B.In the gold mining industry, one of the significant physical properties of the mineral slurry is its density and it is important to be able to measure this parameter in most processes. There are many techniques for determining the density of fluids, but because of the hostile, abrasive nature of mineral slurry, very few of these are suitable, This dissertation describes the deveiopment, construction and testing of a portable, ultrasonic, density measuring instrument. The instrument uses an ultrasonic transducer as the primary measuring element, and system operation is based on the fact that the driving impedance of the transducer varies with changes in the physical properties, and hence the characteristic impedance, of the surrounding medium into which the ultrasonic energy is being transferred. The technique may a-Lao be used to measure the relative concentrations of two liquids in a mixture or emulsion, provided that the characteristic impedances of the liquids are sufficiently dissimilar. The electronic circuitry is fairly straightforward, consisting essentially of an oscillator, driving circuit for the transducer and a voltage monitor to provide a d.c. voltage proportional to the impedance of the transducer, and hence to the density of the surrounding medium. Most of the research has been concentrated on the probe design, as the type of transducer, the type and thickness of facing material and the method of construction all contribute to the sensitivity of the instrument. A design of probe assembly has been developed that may be used for both slurry density measurement and the measurement of the ratio of aqueous to organic liquids in emulsion.Item An investigation into the quality of supply voltage dip-proofing(1998) Lange, Lyle George; Crow, A.With the ever increasing electrical demand on an electrical system, the quality of the supply will be tested more and more. And it is with this deteriorating quality that the topic of voltage dips and depressions has become a contentious issue amounts the industrial sector and supply authorities, hence the means to combat this issue in recent years.