<p>Communication tools such as text-based instant messaging, voice and video relay services, real-time video chat and mobile SMS and MMS have successfully been used among Deaf people. Several years of field research with a local Deaf community revealed that disadvantaged South African Deaf&nbsp / people preferred to communicate with both Deaf and hearing peers in South African Sign Language as opposed to text. Synchronous video chat and video&nbsp / relay services provided such opportunities. Both types of services are commonly available in developed regions, but not in developing countries like South&nbsp / Africa. This thesis reports on a workaround approach to design and develop an asynchronous video communication tool that adapted synchronous video&nbsp / &nbsp / codecs to store-and-forward video delivery. This novel asynchronous video tool provided high quality South African Sign Language video chat at the&nbsp / expense of some additional latency. Synchronous video codec adaptation consisted of comparing codecs, and choosing one to optimise in order to&nbsp / minimise latency and preserve video quality. Traditional quality of service metrics only addressed real-time video quality and related services. There was no&nbsp / uch standard for asynchronous video communication. Therefore, we also enhanced traditional objective video quality metrics with subjective&nbsp / assessment metrics conducted with the local Deaf community.</p>

<p>Communication tools such as text-based instant messaging, voice and video relay services, real-time video chat and mobile SMS and MMS have successfully been used among Deaf people. Several years of field research with a local Deaf community revealed that disadvantaged South African Deaf&nbsp / people preferred to communicate with both Deaf and hearing peers in South African Sign Language as opposed to text. Synchronous video chat and video&nbsp / relay services provided such opportunities. Both types of services are commonly available in developed regions, but not in developing countries like South&nbsp / Africa. This thesis reports on a workaround approach to design and develop an asynchronous video communication tool that adapted synchronous video&nbsp / &nbsp / codecs to store-and-forward video delivery. This novel asynchronous video tool provided high quality South African Sign Language video chat at the&nbsp / expense of some additional latency. Synchronous video codec adaptation consisted of comparing codecs, and choosing one to optimise in order to&nbsp / minimise latency and preserve video quality. Traditional quality of service metrics only addressed real-time video quality and related services. There was no&nbsp / uch standard for asynchronous video communication. Therefore, we also enhanced traditional objective video quality metrics with subjective&nbsp / assessment metrics conducted with the local Deaf community.</p>

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Student Number : 9306442N - PhD thesis - School of Electrical and Information Engineering - Faculty of Engineering and the Built Environment / This thesis describes the design, construction and evaluation of a prototype modified tubular linear synchronous motor. The linear motor has a long static primary and a short permanent magnet mobile secondary. The design is unique in that a tubular topology has been modified to allow access to the moving secondary section. This modification means that this design can be used in long distance applications. The application for this research is the use of linear motors in rope-less vertical trans- portation systems in ultra deep level mines. The design of the linear motor has been analysed from an electrical, magnetic, mechanical and thermal perspective. Finite Element Analysis was used to predict the performance of the linear motor. The design of the secondary section has been optimised to produce the greatest possible thrust force while reducing the effects of the cogging forces. The linear motor has been tested extensively and the results correlate with theoretical predictions from the Finite Element Analysis. This project proves that the modified tubular lin- ear synchronous motor is a viable technology that can be used in rope-less vertical transportation systems.