Masters Degrees (Electrical and Electronic Engineering)
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Browsing Masters Degrees (Electrical and Electronic Engineering) by browse.metadata.advisor "Blanckenberg, M. M."
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- ItemAutomated pediatric cardiac auscultation(Stellenbosch : University of Stellenbosch, 2005-03) De Vos, Jacques Pinard; Blanckenberg, M. M.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.Most of the relevant and severe congenital cardiac malfunctions can be recognized in the neonatal period of a child’s life. The delayed recognition of a congenital heart defect may have a serious impact on the long-term outcome of the affected child. Experienced cardiologists can usually evaluate heart murmurs with a high sensitivity and specificity, although non-specialists, with less clinical experience, may have more difficulty. Although primary care physicians frequently encounter children with heart murmurs most of these murmurs are innocent. The aim of this project is to design an automated algorithm that can assist the primary care physician in screening and diagnosing pediatric patients with possible cardiac malfunctions. Although attempts have been made to automate screening by auscultation, no device is currently available to fulfill this function. Multiple indicators of pathology are nonetheless available from heart sounds and were elicited using several signal processing techniques. The three feature extraction algorithms (FEA’s) developed respectively made use of a Direct Ratio technique, a Wavelet analysis technique and a Knowledge based neural network technique. Several implementations of each technique are evaluated to identify the best performer. To test the performance of the various algorithms, the clinical auscultation sounds and ECG-data of 163 patients, aged between 2 months and 16 years, were digitized. Results presented show that the De-noised Jack-Knife neural network can classify 163 recordings with a sensitivity and specificity of 92 % and 92.9 % respectively. This study concludes that, in certain conditions, the developed automated auscultation algorithms show significant potential in their use as an alternative evaluation technique for the classification of heart sounds in normal (innocent) and pathological classes.
- ItemDesign of a haptic controller for excavators(Stellenbosch : University of Stellenbosch, 2009-03) Van der Zee, Lodewyk Francois; Blanckenberg, M. M.; Treurnicht, N. F.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.The input orientation of the excavators in use today usually comprises two joysticks that control the actuator links individually. In order to perform an excavation task, several different combinations of joystick inputs are required, placing high psychomotor demands on the operator. In training an operator this creates a steep learning curve, with a lengthy training time and a reasonable amount of experience being required to perform an excavation task skilfully. In this master’s thesis a haptic1 device was developed, resolving input ergonomics and creating a single input device capable of providing feedback to the operator. The design and construction of the haptic device, with the related control scheme, is presented and discussed. The control scheme combines position and rate control, and relates all the actuator joint positions to a single end-effector point. The control and ergonomic aspects of the haptic device were tested and compared to the traditional two joystick control setup by means of the implementation of a virtual excavator simulator. The simulation was developed in MATLAB, and virtual excavator displayed in an openGL window. The objective of this study was to evaluate the human factors related to the input orientation. Ten inexperienced test subjects were recruited to perform four sets of tests, where each test required a different level of operator skill. The results indicated that, on average, the test subjects had an increased level of performance after training on the haptic device. These results strongly support the hypothesis that haptic control simplifies the operational tasks required for operating an excavator. 1The word haptic means of, or relating to, the sense of touch, or tactile
- ItemThe design of a hysteroscopy simulator(Stellenbosch : University of Stellenbosch, 2007-12) Kruger, Gerrit V.; Blanckenberg, M. M.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.This thesis documents the research, design and implementation of a virtual hysteroscopy simulator. A hysteroscopy is a medical procedure used in the field of obstetrics and gynaecology. The system consists of a mechanically modelled hysteroscope connecting to any personal computer using USB, and is plug and play compatible on any modernWindows operating system. The scope interfaces with custom-designed software, which simulates a patient’s anatomy and thus creates a virtual operating environment. The software incorporates features like simulated soft tissue and an ablation algorithm. This system is developed with the aim to aid the young or inexperienced surgeon with hands-on training, developing his hand-eye coordination and visual and surgical skills used in this procedure.
- ItemEfficient registration of limited field of view ocular fundus imagery(Stellenbosch : Stellenbosch University, 2013-12) Van der Westhuizen, Christo Carel; Blanckenberg, M. M.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Diabetic- and hypertensive retinopathy are two common causes of blindness that can be prevented by managing the underlying conditions. Patients suffering from these conditions are encouraged to undergo regular examinations to monitor the retina for signs of deterioration. For these routine examinations an ophthalmoscope is used. An ophthalmoscope is a relatively inexpensive device that allows an examiner to directly observe the ocular fundus (the interior back wall of the eye that contains the retina). These devices are analog and do not allow the capture of digital imagery. Fundus cameras, on the other hand, are larger devices that o er high quality digital images. They do, however, come at an increased cost and are not practical for use in the eld. In this thesis the design and implementation of a system that digitises imagery from an ophthalmoscope is discussed. The main focus is the development of software algorithms to increase the quality of the images to yield results of a quality closer to that of a fundus camera. The aim is not to match the capabilities of a fundus camera, but rather to o er a cost-e ective alternative that delivers su cient quality for use in conducting routine monitoring of the aforementioned conditions. For the digitisation the camera of a mobile phone is proposed. The camera is attached to an ophthalmoscope to record a video of an examination. Software algorithms are then developed to parse the video frames and combine those that are of better quality. For the parsing a method of rapidly selecting valid frames based on colour thresholding and spatial ltering techniques are developed. Registration is the process of determining how the selected frames t together. Spatial cross-correlation is used to register the frames. Only translational transformations are assumed between frames and the designed algorithms focuses on estimating this relative translation in a large set of frames. Methods of optimising these operations are also developed. For the combination of the frames, averaging is used to form a composite image. The results obtained are in the form of enhanced grayscale images of the fundus. These images do not match those captured with fundus cameras in terms of quality, but do show a signi cant increase when compared to the individual frames that they consists of. Collectively a set of video frames can cover a larger region of the fundus than what they do individually. By combining these frames an e ective increase in the eld of view is obtained. Due to low light exposure, the individual frames also contain signi cant noise. In the results the noise is reduced through the averaging of several frames that overlap at the same location.
- ItemImplementation of a proton therapy supervisory system for iThemba Labs(Stellenbosch : Stellenbosch University, 2012-12) Qhobosheane, Sehlabaka; Blanckenberg, M. M.; Muller, N.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.Please refer to full text for abstract.
- ItemAn infrared earth horizon sensor for a LEO satellite(Stellenbosch : University of Stellenbosch, 2008-03) Van Rensburg, Helgard Marais; Blanckenberg, M. M.; Steyn, W. H.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.Horizon sensing is an effective way to determine the pitch and roll of a LEO satellite and Earth horizon sensors that operate in the visible range of the electromagnetic spectrum are commonly used. These sensors have the disadvantage that they cannot operate when the satellite is in eclipse. Earth horizon sensors that operate in the infrared spectral range are a solution to take attitude measurements when the satellite is in eclipse. Until recently infrared detectors could only operate at very low temperatures and needed to be cryogenically cooled. The result was that their power consumption and physical characteristics (like dimensions and mass) were such that they were not suitable for use in small and medium LEO satellites. As a result of technology expansion in the field of infrared imagers the past few years, infrared imagers were developed which do not require cooling. The scope of this project was to develop and implement an Earth horizon sensor by using a low-cost, uncooled infrared imager. The performance and physical characteristics of various imager were evaluated and it was decided to select a low resolution thermopile imager mainly as a result of the cost limitations of the project. Software algorithms were then evaluated and selected for horizon detection and attitude determination. The Earth horizon sensor that was developed did not comply with the accuracy requirement (3s < 0.1o) that was set for the project because of the low resolution of the sensor. Methods to improve the accuracy were investigated and finally a sub-pixel edge estimation algorithm was developed and implemented which resulted in an improvement of 69% in the pitch accuracy and 49% in roll accuracy. With the sub-pixel edge estimation algorithm implemented the horizon sensor almost met the accuracy requirements (s < 0.0811o for pitch and s < 0.2944o for roll). This project confirms that, with further improvement to the design and test facilities, developing a low-cost, uncooled infrared Earth horizon sensor that meets the accuracy requirements is feasible.
- ItemA Java bytecode compiler for the 8051 micro-controller(Stellenbosch : Stellenbosch University, 2002-03) Mbhambhu, Tsakani Joseph; Blanckenberg, M. M.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic engineering.ENGLISH ABSTRACT: This report describes the development of a Java Bytecode Compiler (JBC) for the 8051 micro-controller. Bytecodes are found in the class file generated when a Java source file is compiled with the java compiler (javac). On Java platforms, the Java Virtual Machine (JVM) interprets and executes the bytecodes. Currently existing Java platforms do not support programming the 8051 using Java. As an 8-bit micro-controller with only 64 KB of total memory, the 8051's word size and memory is too limited to implement a NM. Moreover, full applications of the 8051 require that it handles hardware interrupts and access 110 ports and special registers. This thesis proposes a JBC to compile the standard bytecodes found in the class file and generate equivalent assembly code that can run on the 8051. The JBC was tested on the 8051 compatible AT89C52*44 micro-controller with a program that simulates an irrigation controller. The code generated by the JBC executes correctly but is large in size and runs slower than code of a program written in assembly. Conclusions drawn are that the JBC can be used to compile Java programs intended for the 8051 and its family of micro-controllers. In particular, it is especially a good tool for people who prefer Java to other languages. The JBC is suitable for smaller programs that do not have efficiency as a major requirement.
- ItemA mass memory system for satellites using field programmable gate arrays and synchronous DRAM(Stellenbosch : Stellenbosch University, 2006-12) Vosloo, Jacobus Jurie; Blanckenberg, M. M.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Technological advances have increased storage requirements on board satellites tremendously in recent years. Storage normally used on satellites is expensive and often complex and rigid hardware systems are needed to access the large number of interconnected devices effectively. This thesis looks at the lower cost higher volume alternative of Synchronous DRAM, coupled with the flexibility of reprogrammable logic. A VHDL design of the system is done using a narrow data bus and no address bus and includes SDRAM control, reducing external components. Suggestions are also made to reduce the inherent risk associated with the technologies used to implement the design.
- ItemNie-destruktiewe klankonttrekking, restourasie en spraakverheffing van Edison-fonograafsilinders(Stellenbosch : Stellenbosch University, 2003-12) Van der Westhuizen, Ewald; Blanckenberg, M. M.; Schwardt, L.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Two non-destructive methods of extracting audio from Edison phonographic cylinders were investigated. A recording device with high accuracy positioning was designed and manufactured. A microscopic image method was investigated first. Surface images of the cylinder were obtained using a webcamera. An audio signal was then extracted from the width modulation. Results were not pleasing as echoes caused by intergroove modulation were perceptable. The audio also lacked resolution. The true modulation of the audio is not embedded in the width, but in the depth of the groove. The second audio extraction method involved using a laser pick-up from a compact disc player to measure the depth of the groove. Three laser recording methods were investigated. The first was forward recording, that measured the depth modulation in the recording direction of the groove. The second method, backward recording, was identical to forward recording with the mechanical system moving in reverse. Four recordings from different positions in the groove were combined to create an audio signal. This combination of recordings showed a substantial improvement in the signal-to-noise ratio. A third recording method, transverse recording, that measured the whole depth profile of the groove was also investigated. The groove profile was then processed to an audio signal. A manual audio restoration program was written to replace visible sections of distorted data with better interpolations. Two speech enhancement methods were investigated, the first being the most commonly used speech enhancement method for digital audio restoration, Short-Time Spectral Attenuation (STSA). The second method is based on linear predictive coefficient (LPC) estimation of short-time frames. The two methods were evaluated by means of listening tests. The LPC enhancement method was preferred because it enhanced the intelligibility of the speech.
- ItemThe selection and single event upset testing of a DSP processor for a LEO satellite(Stellenbosch : Stellenbosch University, 2002-03) Berner, Heiko; Blanckenberg, M. M.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: After successful use of a DSP processor onboard the SUNSAT satellite, the need arose for a faster floating-point processor. A list of possible processors was generated from various selection criteria. Two suitable DSP processors were chosen, and because no radiation information was available for one of them, the decision was made to perform radiation tests on it. The procedures used to test the processor are described in detail so the same methods can be used for future radiation tests. An error detection and correction circuit was implemented to check and correct upsets in the on-chip memory of the DSP processor. This ensures that the processor code and data stays intact.
- ItemUpgrading of a radar system to implement a firmware based pulse compressor(Stellenbosch : Stellenbosch University, 2007-03) Rust, Johannes Stephanus Warnich; Blanckenberg, M. M.; Wolfaardt, P. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: This project investigates the improvement of an existing radar system by means of currently available technologies and signal processing techniques. Upgrades are aimed to improve the system's speci cations with focus on range resolution. Pulse compression and Doppler processing techniques are used to accomplish the improvement in range resolution. The use of pulse compression however resulted in numerous modi cations to the RF sub-system required by the introduction of Direct Digital Synthesizer modules. A full replacement of the existing signal processor with a Doppler processing based signal processor implemented on a single programmable rmware device was designed. Certain sections of this signal processor were implemented and tested. Pulse compression was successfully implemented and tested in both the transceiver and signals processor sections.
- ItemVideo camera design and implementation for telemedicine application(Stellenbosch : Stellenbosch University, 2005-04) Behaimanot, Kibreab Ghebrehiwet; Blanckenberg, M. M.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Primary health care telemedicine services require the acquisition and transmission of patient data including high quality still and video images via telecommunication networks. The objective of this thesis is to investigate the implementation of a generalpurpose medical camera as an alternative to the complex and costly CCD based cameras generally in use at present. The design is based on FillFactory’s SXGA (1280 ×1024) CMOS image sensor. A low-cost Altera Cyclone FPGA is used for signal interfacing, filtering and colour processing to enhance image quality. A Cypress USB 2.0 interface chip is employed to isochronously transfer video data up to a maximum rate of 23.04 MBytes per second to the PC. A detailed design and video image results are presented and discussed; however the camera will need repackaging and an approval for medical application by medical specialists and concerned bodies before releasing it as full-fledged product.