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Thesis (M.S.)--Kutztown University of Pennsylvania, 2002. / Source: Masters Abstracts International, Volume: 45-06, page: 2720. Typescript. Abstract precedes thesis as preliminary leaves 1-2. Includes bibliographical references (leaves 34-35).

Submitted in fulfillment of the academic requirements for the Master’s Degree of Technology: Electrical Engineering – Light Current, Durban University of Technology, 2012. / The development of a transit radio telescope at the hydrogen line frequency of 1420 MHz is described. The telescope antenna uses a 5 m diameter parabolic reflector with an estimated efficiency of 50 % and an F/D ratio of 0.5. The gain of the antenna at 1420 MHz (wavelength of 21.1 cm) is approximately 35 dB with a beamwidth of approximately 3°. The antenna is mounted on a concrete beam at the first floor level, running between two 5 floor tower blocks on the Steve Biko campus of the Durban University of Technology. The majority of the components of the radio telescope antenna and receiver were designed and manufactured at the Durban University of Technology by students of the Departments of Mechanical and Electronic Engineering. The measured sensitivity of the receiver is approximately -94 dBm with a bandwidth of approximately 80 MHz. Radio sources successfully detected by the radio telescope include the Sun, the Moon, Sagittarius A, Centaurus A and Vela X.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The use of Focal Plane Arrays (FPAs) as suitable feed-structures for the Parabolic Dish Reflector antennas that are intended to form a large part of the Square Kilometre Array (SKA) is currently the topic of conversation in various SKA research groups. The simulation of these structures however, relies on intensive computational resources, which can result in very long simulation runtimes - a serious problem for antenna designers. It was the purpose of the research to investigate efficient simulation techniques, based on the Method of Moments (MoM). In this thesis, the reader will be introduced to ways of improving FPA design by using resources such as High Performance Clusters, developing efficient MoM formulations for FPAs such as the Vivaldi antenna array and by developing efficient solution techniques for the resulting MoM equations by using techniques such as the Characteristic Basis Function Method (CBFM). In addition to the above mentioned methods, the concept of distributed computing is explored as a way to further aid the antenna designer in obtaining desired results in a reasonable time and with sufficient accuracy. / AFRIKAANSE OPSOMMING: Die gebruik van Fokus Punt Samestellings (FPS) vir die voer van Paraboliese Skottel Antennas in die Square Kilometer Array (SKA), geniet tans baie aandag in verkeie navorsing-sirkels. Die analise van hierdie samestellings vereis egter intensiewe berekenings-infrastrukture, wat tot lang simulasies kan lei - ’n ernstige probleem vir antenna ontwerpers. Die doel van die skrywer se navorsing was om effektiewe simulasie metodes te ondersoek, gebaseer op die Moment Metode. In hierdie tesis, sal die leser bekendgestel word aan verskeie metodes om die ontwerp van Fokus Punt Samestellings doeltreffend te verrig; nl. die gebruik van Parallel Rekenaar Klusters, die ontwikkeling van effektiewe Moment Metode kode vir samestellings soos die Vivaldi antenna konfigurasie, asook die ontwikkeling van effektiewe oplos-metodes vir die matrikse wat deur die Moment Metode gelewer word, deur die sogenaamde Karakteristieke Basis Funksie Metode (KBFM) te gebruik. Hierby ingesluit word die konsep van verspreide numeriese berekening ondersoek, as ’n manier waarop die antenna ontwerper resultate binne ’n aanvaarbare tyd en akkuraatheid kan verkry.

Thesis submitted in fulfilment of the requirements for the degree Doctor of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology, 2013 / Networked Control Systems is a control system where the plant and the controller exchange information via a shared communication network and the network is considered as part of the closed loop control system. Unfortunately the network introduces network induced random varying time delays and data packet loss amongst the communication network imperfections. The network delays are considered to be between the controller and the actuator and between the sensor and the controller. These network imperfections degrade the performance of the closed loop control system and result in closed loop system instability. The complexity of measuring the communication network imperfection in networked control systems makes it difficult for the control engineers to develop methods for design of controllers that can incorporate and compensate these imperfections in order to improve the performance of the networked control systems. In this thesis a co-simulation toolset called LabNS2 is developed to address the first problem of measuring the communication network imperfections by providing an ideal environment that can be used to investigate the influence of network time delays or packet loss. The software environment of the toolset is based on LabVIEWTM and Network Simulator Version 2 (NS2). A new robust predictive optimal controller design method is developed to address the problem of the destabilising effect of the network induced time delay between the controller and the actuator. The design approach is based on time shifting of the optimisation horizon and a state predictor. The design of the controller is based on a model of the plant with delay in the control vector equal to the delay between the controller and the actuator or to the sum of the delays between the controller and the actuator and between the sensor and the controller. The time shifting approach allows the design of the controller to be performed for a model without time delay. Then the control action is based on the future values of the state space vector estimates. The state predictor is developed to predict these future values of the state using the present and past values of the state estimates and control actions. This technique is made possible by the use of the plant model Transition Matrix. A Discrete Kalman Filter is modified to address the problem of the destabilising effect of the network induced time delay between the sensor and the controller. An additional state estimation vector is added to the filter estimate at every current moment of time. iv The developed methods are implemented for networked control of a dish antenna driven by two stepper motors. The outcomes of the thesis can be used for the education and fundamental research purposes, but the developed control strategies have significant sense towards the Square Kilometer Array projects and satellite systems industry. / National Research Foundation