Masters Degrees (Electrical and Electronic Engineering)
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Browsing Masters Degrees (Electrical and Electronic Engineering) by browse.metadata.type "Masters"
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- ItemDesign and implementation of a two-element interferometer(Stellenbosch : Stellenbosch University, 2022-04) Schleich, Stella; De Villiers, Dirk; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: This thesis describes the design and implementation of a two-element interferometer. This is aimed to exhibit the basis of radio astronomy and act as a demonstrator of interferome tery. The instrument consists of two identical channels with three subsystems within the channels. The first is an offset reflector antenna system, where axially corrugated horn antennae are designed as the feed antennae. The second subsystem is a receiver chain, which consists of off-the-shelf components. A dual-conversion superheterodyne receiver is designed to process the radio frequency signal before digitisation. The last subsystem is a digital correlator. This consists of digitisation of the signal and correlation between the two receiver channels which is implemented using Red Pitaya and MATLAB. The system has an operating frequency of 12 GHz with a 60 MHz bandwidth. The chosen source for observation is the sun and the instrument is oriented on a east-west direction, while taking meridian drift scan observations. The observations show that it is possible to detect the sun.
- ItemDesign of a soluble P-selectin biosensor for detecting platelet activation(Stellenbosch : Stellenbosch University, 2019-12) Laubscher, Riaan Willem; Perold, W. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: The main causes of death are shifting from communicable disease, such as Tuberculosis, to non-communicable disease, such as cardiovascular disease. This disease, along with many other diseases, have been associated with chronic in ammation which is also interrelated with activated blood platelets. When platelets activate, they release biomolecules that can be used as biomarkers for diagnosing or monitoring diseases. Currently, there are no highly accurate tests that can measure the level of chronic in ammation and conventional tests ar either costly, time-consuming, or unpractical in remote areas. Therefore, there is room for improvement in the area of diagnostics of chronic in ammation. This project set out to find a potential biomarker that is a good indicator of platelet activation and is upregulated in an in ammatory individual. Soluble P-selectin was identified as a platelet membrane receptor that is shed upon activation into the blood stream. A study was conducted about the different biosensing techniques, and a label-free electrochemical biosensor approach was chosen for this work. Electrochemical biosensors have been shown to be robust and can be manufactured with relatively low-cost materials. Commercial graphene oxide and carbon nanofiber screen printed electrodes were acquired to establish a working proof of concept. The sensors were electrografted with 4-carboxyphenyl diazonium salt to create support groups for the subsequent attachment of human soluble P-selectin antibodies through EDC/NHS crosslinking chemistry. Square wave voltammetry was identified as a very sensitive diagnostic technique that can be used to quantify the concentration of biomolecules in a sample. Ferricyanide/ferrocyanide and hexaammineruthenium(III) chloride was used as the two redox probes for the voltammetry measurements. In parallel, an application specific potentiostat device was developed to apply the square wave potential and measure the sensor response. The portable device had a potential range of ±1:65 V and a current range of ±244 µA. The project used three different approaches for the detection tests over a range of five full scale experiments. Even though none of the approaches were successful in realizing a linear detection range, one approach showed a difference in response between sP-selectin and non-specific CRP. Due to an unfortunate event with the sensors at the closing of the project, the home-built potentiostat could not be used to perform the final detection measurements of the immunosensor. However, it showed excellent performance against a conventional potentiostat device for detecting ferricyanide/ferrocyanide concentrations in the range of 0.5 to 5 mM. The work done in this thesis showed that if the immunosensor was optimized with the necessary equipment and materials, it would have been possible to use the home-built potentiostat to quantify the level of soluble P-selectin in a sample.