In South Africa, there is an increasing interest in installing rooftop mounted solar photovoltaic systems. However, financing the photovoltaic systems causes most interest to be abandoned, largely due to the cost required to replace a building's asbestos roof. An alternative solution to replacing an asbestos roof is to install a ground-mounted photovoltaic system, which is more costly compared to a rooftop mounted system. This study aims to determine if a ground-mounted or a rooftop mounted solar photovoltaic system is the most financially feasible solar photovoltaic configuration. In this study three photovoltaic systems were analysed, all of which are installed in Atlantis, Western Cape (WC). Since all three systems are in the same area, they are all exposed to the same metrological conditions, allowing for identical energy generation potential. Two of the photovoltaic systems are ground-mounted systems located respectfully at the South African Renewable Energy Incubator (SAREBI) and at Stripform Packaging. The third system is a rooftop mounted system located at SA Tyre Recyclers. The photovoltaic system at SAREBI is a 9.75 kWp system consisting of 30 Canadian Solar CS6U-325P modules, one Schneider Electric 20 kW inverter, a tilt angle of 15° and an azimuth angle of -19°. The photovoltaic system at SA Tyre Recyclers is a 231 kWp system consisting of 700 JA Solar JAP72S-01-330-SC modules, 7 SolarEdge 27.6 kW inverters, a tilt angle of 13° and an azimuth angle of 22°. The photovoltaic system at Stripform Packaging is a 20.1 kWp system consisting of 60 Canadian Solar CS6U-335P modules, one SMA 20 kW inverter, a tilt angle of 15° and an azimuth angle of 46°. To achieve the aim of this study, the performance of each of the solar photovoltaic systems was examined, by comparing their annual specific yield. After which the technical aspects and differences of each of the photovoltaic systems were explored, to illustrate how each of the systems differ technically and how each system can be improved. Finally, the comparative cost of each of the solar photovoltaic systems was examined by analysing the levelized cost of energy (LCOE) and the payback period for each of the photovoltaic systems. The results demonstrated that from an annual specific yield perspective, the ground-mounted configuration was the best performing, whilst from a financial perspective, the rooftop mounted configuration had the lowest levelized cost of energy (LCOE) and payback period. However, installing a ground-mounted system is more financially feasible than replacing an asbestos roof and then installing a rooftop mounted system. In conclusion, by fully understanding the performance, payback period and levelized cost of energy, a clear understanding of potential risk can be determined, thus making the installation of photovoltaic systems more appealing for financiers. It is recommended that this study be repeated in a manner in which each of the photovoltaic system configurations are constructed consisting of all the same photovoltaic components, measuring equipment, tilt and azimuth angles. All of which would result in two identical photovoltaic systems where one is installed on a rooftop and the other installed on the ground. Once the two photovoltaic system configurations are equal in all aspects, an accurate comparison to determine which configuration is the most optimal performer and which is the most financially viable will be possible.

In this study, 1/2 £f mode SMR filters on Si substrates by reactive RF magnetron sputtering method were fabricated. In addition, the thermal annealing process was adopted to improve the insertion loss of SMR filter. The Bragg reflector in SMR is alternately mounted by high and low acoustic impedance materials, with low acoustic impedance material of SiO2 and high acoustic impedance material of W. We could obtained three kinds of crystal structures of W, £\ - phase W¡B£] - phase W and £\ & £] - mixed phase W, respectively, it could be obtained by modulating the sputtering recipe. £\ - phase W possesses higher acoustic impedance and is suitable for high acoustic impedance material in bragg reflector. The piezoelectric layer of ZnO is sputtered by a 2-step deposition method on Si substrates with different temperature. The ZnO film with stronger C-axis (002) orientation and lower surface roughness value could be obtained at substrate temperature of 200 ¢J, which is suitable for fabricating SMR device. After the SMR filter had completed, the device is thermal annealed with CTA¡BRTA and RTA in O2 ambient. After thermal treatment, the properties of filters are improved. The properties could be optimized with RTA in O2 ambient condition. The insertion loss was improved from -12.03 dB to -6.96 dB. The film characteristics of ZnO changes after the SMR processed thermal treatment. The strongest C-axis (002) intensity with the lowest surface roughness value at 400 ¢J annealing temperature could be obtained, in that, approximate equal Zn:O ratio could be achieved by XPS examination. The central frequency of SMR filter drifted to higher value as the temperature of thermal treatment increased, which is attributed to the changes of the ZnO acoustic velocity(£o) after thermal treatment.

Depending upon their nature, Outdoor AR applications can be deployed on head mounted displays (HMD) like Google glass or handheld Displays (HHD) like smartphones. This master’s thesis investigates novel gesture-based interaction techniques and applications for a HMD-HHD hybrid system that account for advantages presented by each platform. Prior research in HMD-HHD hybrid systems and gestures used in VR and surface computing were taken into account while designing the applications and interaction techniques. A prototype system combining a HMD and HHD was developed and four applications were created for the system. For evaluating the gestures, an application that compared four of the proposed gestures for selection tasks was developed. The results showed a significant difference between the different gestures and that the choice of gesture for selection tasks using a hybrid system depended upon application requirements like speed and accuracy.

This study investigated the performance and cost of scarification with a tractormounted excavator. Due to variations in terrain conditions the performance variedbetween 0.08 and 0.11 ha/E15h and, with a machine cost of 366 SEK/h, the cost ofscarification varied between 3 330 and 4 750 SEK/ha.

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Virtual reality (VR) headsets are becoming more common and will require evolving input mechanisms to support a growing range of applications. Because VR devices require users to wear head-mounted displays, there are accomodations that must be made in order to support specific input devices. One such device, a keyboard, serves as a useful tool for text entry. Many users will require assistance towards using a keyboard when wearing a head-mounted display. Developers have explored new mechanisms to overcome the challenges of text-entry for virtual reality. Several games have toyed with the idea of using motion controllers to provide a text entry mechanism, however few investigations have made on how to assist users in using a physical keyboard while wearing a head-mounted display. As an alternative to controller based text input, I propose that a software tool could facilitate the use of a physical keyboard in virtual reality. Using computer vision, a user€™s hands could be projected into the virtual world. With the ability to see the location of their hands relative to the keyboard, users will be able to type despite the obstruction caused by the head-mounted display (HMD). The viability of this approach was tested and the tool released as a plugin for the Unity development platform. The potential uses for the plugin go beyond text entry, and the project can be expanded to include many physical input devices.

Graduation date: 1997

This dissertation examines the developments and progress of spatial calibration procedures for Optical See-Through (OST) Head-Mounted Display (HMD) devices for visual Augmented Reality (AR) applications. Rapid developments in commercial AR systems have created an explosion of OST device options for not only research and industrial purposes, but also the consumer market as well. This expansion in hardware availability is equally matched by a need for intuitive standardized calibration procedures that are not only easily completed by novice users, but which are also readily applicable across the largest range of hardware options. This demand for robust uniform calibration schemes is the driving motive behind the original contributions offered within this work. A review of prior surveys and canonical description for AR and OST display developments is provided before narrowing the contextual scope to the research questions evolving within the calibration domain. Both established and state of the art calibration techniques and their general implementations are explored, along with prior user study assessments and the prevailing evaluation metrics and practices employed within. The original contributions begin with a user study evaluation comparing and contrasting the accuracy and precision of an established manual calibration method against a state of the art semi-automatic technique. This is the first formal evaluation of any non-manual approach and provides insight into the current usability limitations of present techniques and the complexities of next generation methods yet to be solved. The second study investigates the viability of a user-centric approach to OST HMD calibration through novel adaptation of manual calibration to consumer level hardware. Additional contributions describe the development of a complete demonstration application incorporating user-centric methods, a novel strategy for visualizing both calibration results and registration error from the user’s perspective, as well as a robust intuitive presentation style for binocular manual calibration. The final study provides further investigation into the accuracy differences observed between user-centric and environment-centric methodologies. The dissertation concludes with a summarization of the contribution outcomes and their impact on existing AR systems and research endeavors, as well as a short look ahead into future extensions and paths that continued calibration research should explore.