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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Research into adventitious lung sound signals originating from pulmonary tuberculosis using electronic auscultation

Becker, Konrad Wilhelm 03 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009. / Pulmonary tuberculosis is a common and potentially deadly infectious disease, commonly affecting the respiratory area. Over one-third of the world’s population is infected with the tuberculosis bacterium. Since pulmonary tuberculosis damages the respiratory area, the sound properties of infected lungs differ from those of non-infected lungs. However, auscultation is often ruled out as a reliable diagnostic technique due to the random position and severity of damage to the lungs as well as requiring the personal and trained judgment of an experienced medical practitioner. This project investigates a possible improvement in the pulmonary diagnostic and treatment field by applying electronic and computer-aided sound analysis techniques to analyze respiratory actions beyond human audible judgment. Respiratory sounds of both healthy subjects and subjects who were infected with pulmonary tuberculosis were recorded from seven locations per lung on both the posterior and anterior chest walls, using self-designed hardware. Adaptive filtering signal and analysis techniques yielded a wide range of signal features. This included analysis for time, frequency and both wheeze and crackle adventitious respiratory sounds. Following the analysis, statistical methods identified the most attractive signal measurements capable of separating the recordings of healthy and unhealthy respiratory sounds. Selected signal features were used with neural network optimization to obtain a successful implementation for the semi-automated identification of healthy and unhealthy respiratory sounds originating from pulmonary tuberculosis, with a performance of over 80% for sensitivity, specificity and accuracy. The success of categorizing the recordings justifies the capabilities of the digital analysis of respiratory sounds and supports an argument for further research and refinement into the assessment of pulmonary tuberculosis by electronic auscultation. Further research is recommended, with improvements justified and highlighted in this report.

Nystagmus and eye reflex sensor

Swart, Wayne 12 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Nystagmus is an eye movement pattern that consists of a drifting gaze component, known as the slow phase, followed by a corrective quick phase component. The presence of nystagmus or the lack thereof under certain conditions can be used for various diagnostic purposes including the diagnosis of physiological, pathological and neurological conditions. The angular velocity of the quick phase can make the detection of nystagmus a challenging task for the untrained eye, since the quick phases are usually comparable with saccadic eye motions. The goal is thus to develop a fully automated diagnostic tool that can identify the presents of nystagmus in a patient’s eye motions. In this thesis, an appropriate eye tracking method was selected from a number of eye tracking methods that are commonly implemented in the literature. A video-oculography goggle concept was chosen based on criteria such as invasiveness, sampling rate, accuracy and telemedicine capability, amongst other nystagmus related necessities. A binocular video-oculography concept was chosen that satisfied the technical requirements and provided a cost-effective design. An automated analysis algorithm was developed for automatic nystagmus identification from eye motion data. The algorithm was validated by testing the performance of the algorithm on an optokinetic nystagmus signal. It proved to provide a reliable automatic identification of nystagmus beats, even in signals that contained nystagmus as well as random motion components. A statistical analysis showed that the algorithm provided a sensitivity of 91.8% and a specificity of 96.5% for pure nystagmus signals, and a sensitivity and specificity of 87.8% and 91.1% respectively for mixed signals. / AFRIKAANSE OPSOMMING: Nystagmus is ’n oogbewegingspatroon wat bestaan uit ’n dwalende tuurkomponent, wat die stadige fase genoem word, gevolg deur ’n vinnige korrigereringsbeweging wat bekend staan as die vinnige fase. Die teenwoordigheid van nystagmus, of afwesigheid daarvan in sekere gevalle, kan gebruik word in ’n verskeidenheid diagnostiese toepassings, onder andere die diagnose van fisiologiese-, patalogiese- en neurologiese kwale. Die hoeksnelheid van die vinnige fase lei daartoe dat nystagmus dikwels moeilik is om te bespeur vir ongeöefende oë, aangesien dit vergelykbaar is met saccade bewegings. Die doel van hierdie navorsing is dus die ontwikkeling van ’n stelsel wat ’n volledige automatiese identifisering van nystagmus kan behartig. ’n Gepaste oogvolgtegniek was gekies vanuit ’n aantal verskillende oogvolgmetodes wat dikwels in die praktyk gebruik word. Die finale keuse was ’n skermbril, video-oogvolgmetode wat gekies was op grond van kriteria soos onder andere, invallendheid, meetfrekwensie, akkuraatheid en geskiktheid vir telemedisyne toepassings. Die ontwikkelde brilkonsep bied ’n koste-effektiewe oplossing, met die moontlikheid om albei oë te volg en bevredig al die bogenoemde tegniese spesifikasies. ’n Geoutomatiseerde nystagmus identifiseringsalgoritme is ontwikkel. Die algoritme se effektiwiteit is getoets op optokinetiese nystagmusseine. Betroubare resultate is vekry vanaf die algoritme, selfs in die geval van gemengde seine wat bestaan uit arbritrêre- en nystagmus komponente. Statistiese analiese het gewys dat die algoritme ’n sensitiwiteit van 91.8% en ’n spesifisiteit van 96.5% kon behaal vir seine met slegs nystagmus inhoud. Vir gemengde inhoud seine het die algoritme ’n sensitiwiteit van 87.8% en spesifisiteit van 91.1% behaal.

Development of a neck palpation device for telemedical environments

Van den Heever, David Jacobus 12 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / An abnormal sized mass in the neck is a common clinical finding and it can be the result of inflammation caused by bacterial or viral infection or it can be due to more serious diseases and malignant tumours. The most popular method of examining the neck is by manual palpation. Other methods include ultrasound, CT scan, MRI and PET. These methods though are expensive to perform and require specialists to interpret the results. The aim of this thesis was to design and develop a neck palpation device for telemedicine applications. The device uses an array of Force Sensing Resistors (FSRs) attached to an inflatable bladder. The bladder is mounted to the inside of a neck brace and it is inflated with an air pump controlled by a computer. As the bladder inflates the sensors press against the patient’s neck and the necessary data can be collected. A technique known as image registration is used to improve the resolution of the images sensed with the FSRs. The device provides a reproducible record of the examination for both the surgeon and the patient’s medical record, and provides the patient information as if the doctor examined the patient with his own hands without physically being there. A prototype of the device was built and used to perform numerous tests. The tests were conducted using different objects which are inserted into a silicone neck to simulate different lymph nodes. The device was used to test for shape, smallest size, different sizes, repeatability and hardness. The results showed that the device works well for spherical objects of different sizes but gives unsatisfactory results when the objects have sharp edges and complex forms. The image registration algorithm enhanced the images to a good representation of the object. Different sizes could be distinguished as well as hardness to some extend.

Conceptual design of a fixtureless reconfigurable automated assembly system

Dymond, F. S. D. 12 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The conceptual design of a fixtureless reconfigurable automated spot welding system for manufacturing subassemblies for residential circuit breakers was investigated. This research was aimed at developing a possible low cost automation alternative to a South African industrial manufacturer, which is presently heavily dependent on personnel for manual assembly of their core products. System reconfiguration allows for the assembly of a range of subassemblies with geometric component variation on a given system configuration, as well as the potential for the system to be reconfigured to assemble other ranges of circuit breaker subassemblies. The subassembly selected as focus consists of six different components, which vary geometrically from one product variant to another. A fixtureless approach was selected, to minimise reconfiguration down time and the need for reconfigurable fixtures since reconfigurable fixtures have not found significant acceptance in industry. This varies from a fixture-based approach, which was considered in related research. The conceptual assembly system presented here consists of the following modules: a flexible vision based part feeder, twin 6 DOF robotic manipulators each with a multipurpose gripper, and a stationary spot welding station. Critical conceptual design elements were further investigated to refine their selection and confirm feasibility with respect to the target industry application. This process ended with a preliminary cost estimate which served as a basis for comparison between the fixtureless, fixture-based and present manual assembly process. The fixtureless concept was overall more expensive than the fixture-based concept, primarily because of the limits to production throughput. The fixtureless concept was however cheaper than the present manual assembly approach but had a far longer payback period than desired by the industry. The complexity and possible uncertainties of the concept combined with the long payback period indicated that the fixtureless concept is not suitable for the target application. / AFRIKAANSE OPSOMMING: Die konsepsionele ontwerp van 'n setmaatlose herkonfigureerbare outomatiese puntsweisstelsel vir die vervaardiging van subsamestellings van huishoudelike stroombrekers is ondersoek. Hierdie navorsing is gemik op die ontwikkeling van 'n moontlike lae koste outomatiese alternatief vir 'n Suid Afrikaanse industriële vervaardiger, wat tans sterk afhanklik is van werkers wat die montering van hul kern produkte met die handsamestelling doen. Stelsel herkonfigurasie laat die samestelling van 'n reeks subsamestellings, met geometriese komponentvariasies, op 'n gegewe stelsel toe, asook die potensiaal om die stelsel te herkonfigureer om ander reekse van stroombreker-subsamestellings te monteer. Die subsamestelling wat as fokus gekies is, bestaan uit ses verskillende komponente met geometriese verskille van tussen produkvariante. 'n Setmaatlose benadering is gekies ten einde aftyd vir herkonfigurasie en die noodsaaklikheid van herkonfigureerbare setmate te minimeer, omdat laasgenoemde nie noemenswaardig deur die industrie aanvaar word nie. Hierdie benadering verskil van 'n setmaat-gebaseerde benadering wat in verwante navorsing ondersoek is. Die konsepsionele monteringstelsel wat hier aangebied word, bestaan uit die volgende modules: 'n plooibare, visiegebaseerde voerapparaat; dubbele sesvryheidsgraad robotiese manipuleerders, elk met 'n veeldoelige gryper; en 'n statiese puntsweisstasie. Kritiese elemente van die konseptuele ontwerp is verder ondersoek om hul keuses te verfyn en uitvoerbaarheid in die teiken industriële toepassing te bevestig. Hierdie proses is afgesluit deur 'n voorlopige kosteraming wat gedien het as 'n basis vir die vergelyking van setmaatlose, setmaat-gebaseerde en die huidige handsamestellingstelsels. Die setmaatlose konsep was oorhoofs duurder as die setmaat-gebaseerde konsep, hoofsaaklik as gevolg van beperkings op die produksie-deurset. Die setmaatlose konsep was egter goedkoper as die huidige handmonteringsproses, maar het 'n veel langer terugbetalingstydperk as wat deur die industrie verlang word. Die kompleksiteit en moontlike onsekerhede van die konsep, gepaard met die lang terugbetalingstydperk, dui daarop dat die setmaatlose konsep nie vir die teiken toepassing geskik is nie.

A hydraulic wave energy converter

Du Plessis, Jacques 03 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: As a renewable energy source, wave energy has the potential to contribute to the increasing global demand for power. In South Africa specifically, the country’s energy needs may easily be satisfied by the abundance of wave energy at the South-West coast of the country. Commercially developing and utilizing wave energy devices is not without its challenges, however. The ability of these devices to survive extreme weather conditions and the need to achieve cost-efficacy while achieving high capacity factors are but some of the concerns. Constant changes in wave heights, lengths and directions as well as high energy levels and large forces during storm conditions often lead to difficulties in keeping the complexity of the device down, avoiding over-dimensioning and reaching high capacity factors. The point absorber device developed as part of this research is based on an innovation addressing the abovementioned issues. An approach is followed whereby standard "offthe- shelf" components of a proven hydraulics technology are used. The size of the device is furthermore adaptable to different wave climates, and the need for a control system is not necessary if the design parameters are chosen correctly. These characteristics enable low complexity of the device, excellent survivability and an exceptionally high capacity factor. This may lead to low capital as well as low operationand maintenance costs. In this paper the working principle of this concept is presented to illustrate how it utilises the available wave energy in oceans. The results obtained from theoretical tests correlate well with the experimental results, and it is proven that the device has the ability to achieve high capacity factors. As the device makes use of existing, "off-the-shelf" components, cost-efficient energy conversion is therefore made feasible through this research. / AFRIKAANSE OPSOMMING: As ’n hernubare/ herwinbare energiebron bied golfenergie die potensiaal om by te dra tot die bevrediging van die stygende globale energie-navraag. In spesifiek Suid-Afrika kan die oorvloed van beskikbare golfenergie aan die Suid-Weskus van die land gebruik word om aan die land se energiebehoeftes te voldoen. Betroubaarheid en oorlewing in erge weerstoestande, koste-effektiwiteit en die behaal van hoë kapasiteitsfaktore is beduidende struikelblokke wat oorkom moet word in die poging om ’n golfenergie-omsetter wat kommersieël vervaardig kan word, te ontwikkel. Daarby dra voortdurende veranderings in golfhoogtes, -lengtes en -rigtings sowel as hoë energievlakke en groot kragte tydens storms by to die feit dat dit moeilik is om die kompleksiteit van die stelsel laag te hou. Dit terwyl daar voorkom moet word dat die toestel oorontwerp en verhoed word dat hoë kapsiteitsfaktore bereik word. Die puntabsorbeerder-toestel wat in hierdie navorsing ontwikkel is, bestaan uit ’n ontwerp wat spesifiek ontwikkel is om die bogenoemde probleme aanspreek. ’n Unieke benadering is gevolg waardeur standaard, maklik-bekombare komponente gebruik is en die komponent-groottes ook aangepas kan word volgens golfgroottes. Indien die ontwerpsdimensies akkuraat gekies word, is die moontlikheid verder goed dat ’n beheerstelsel nie geïmplementeer hoef te word nie. Hierdie eienskappe verseker lae stelselkompleksiteit, uitstekende oorlewingsvermoë en ’n uitstaande kapasiteitsfaktor. Lae kapitaal- sowel as onderhoudskostes is dus moontlik. Die doel van hierdie dokument is om die werking van die konsep voor te stel en teoreties sowel as prakties te evalueer. Die resultate van teoretiese toetse stem goed ooreen met eksperimentele resultate, en dit is duidelik dat die toestel hoë kapasiteitsfaktore kan behaal. Aangesien die toestel verder gebruik maak van bestaande komponente wat alledaags beskikbaar is, word die koste-effektiewe omsetting van golfenergie dus moontlik gemaak deur hierdie navorsing.

Continued development of a joint-type knee wear simulator

Van Der Merwe, Johan 03 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This thesis is concerned with the continued development of the Stellenbosch University joint-type knee wear simulator. Initially, information regarding simulators from the literature and commercial entities was collected to provide a knowledge base for current and future work. To further the design of the simulator itself, electronic hardware and software subsystems was developed and evaluated during experimental testing procedures. National Instruments’ cDAQ 9174 data acquisition unit was deemed inadequate for real-time inputoutput control, though proved sufficient for signal capturing purposes in conjunction with LabView software. Furthermore, the various servo-pneumatic sub-circuits’ individual ability to conform to the ISO 14243 series standards’ protocol led to the estimation of measurable performance criteria and the application to a single circuit for illustration. The anterior/posterior actuation circuit in question demonstrated adequate performance for the cases where the piston’s rod was respectively fixed and free to move. In-silico modelling and identification of the relevant servo-pneumatic components then commenced, with the valve and cylinder chamber models yielding adequate estimates of the recorded data. The identified quasi-static friction model proved sensitive to transient effects present within the system, resulting in performance deterioration of the integrated model. Sufficiently accounting for these effects would result in the emergence of the sub-circuit’s model as an invaluable tool in terms of control system development, prediction of the simulator’s behaviour and subsequent design recommendations. Future work therefore concerns improvement, identification and integration of the various sub-circuit models to fully exploit the aforementioned advantages. / AFRIKAANSE OPSOMMING: Hierdie tesis handel oor die voortgesette ontwikkeling van Universiteit Stellenbosch se gewrigstipe knie-afslytingsimulator. Aanvanklik is inligting versamel vanaf literatuur en kommersiële entiteite om sodoende ’n kennisbasis te verskaf vir huidige en toekomstige werk. Elektroniese hardeware en sagteware stelsels is ontwerp en geëvalueer tydens toetsprosedures om die ontwerp van die simuleerder self te verbeter. National Instruments se cDAQ 9174 dataversamelaarseenheid word onvoldoende geag vir intydse inset-uitset beheer, maar wel vir dataversamelingsdoeleindes tesame met LabView sagteware. Die nodigheid om die verskeie servo-pneumatiese sub-stroombane se individuele vermoë om aan te pas by die ISO 14243-reeks se protokol-standaarde te ondersoek, het gelei tot die beraming van meetbare werkverrigtingskriteria en die toepassing daarvan ter illustrasie. Die anterior/posterior stroombaan het voldoende werksverrigting getoon vir studies waar die suier se stang onderskeidelik vas en los was. In-silico modellering en die identifisering van servo-pneumatiese komponente het hierna begin. Die klep en silinderkamer modelle het voldoende skattings gelewer van die gemete data. Die geïdentifiseerde kwasistatiese wrywingsmodel het sensitiwiteit getoon teenoor die oorgangseffekte teenwoordig in die stelsel wat gelei het tot verminderde werksverrigting van die geïntegreerde model. Deur rekening te hou met sulke effekte kan die sub-stelsel se model waardevol wees sover dit beheerstelsel ontwikkeling aangaan, sowel as die voorspelling van die simuleerder se optrede en die daaropvolgende ontwerpsvoorstelle. Toekomstige navorsing kan fokus op die verbetering, identifikasie en integrasie van die verskeie sub-stroombaan modelle om die voorafgenoemde potensiaal ten volle ontgin.

The development of a device for the investigation of dorsiflexion range of the ankle with a capacity to measure pathology, recovery and pharmacological benefit

Botha, Jan 12 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005. / Various ways exist whereby balance abilities of the individual can be assessed. However, most of these are subjective methods. This thesis strives to demonstrate the effectiveness of a new device, the Dorsiflexometer that can be used to objectively assess one’s balance abilities. The Dorsiflexometer was constructed and mathematically modelled using appropriate simplifying assumptions. After its construction, the Dorsiflexometer was tested using two experimental set-ups to obtain raw data. Both these set-ups consisted of the two tiltable platforms equipped with three load cells each, the bridge amplifiers and the personal computer (PC). The only difference in the two experimental set-ups is in the type of test that was performed as well as the bridge amplifiers used. Numerous parameters, such as the radius of movement and the Lyapunov number can be extracted from the raw data. A computer program was written to analyse the raw data and present the results in a user-friendly manner. A new parameter, the Sway Index, was used to obtain a single balance value for the tested individual. This parameter proved useful in quantifying balance. An advanced patent search was carried out before the device was constructed. This was necessary to provisionally patent the device – official application number: 2003/6702.

Conceptual design of a fixture-based reconfigurable spot welding system

Sequeira, Michael Allan 03 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009. / This thesis details the conceptual design of a fixture-based, reconfigurable, automated spot welding system aimed at manufacturing various sub-assemblies of circuit breakers. The welding operations are currently done using manual welding equipment, making this stage of the assembly process highly labour intensive. A range of product models and variants are assembled in quantities requiring frequent change-overs. Low-cost automation within a developing country’s manufacturing industry, more specifically within the Republic of South Africa, is the target context. The chosen design restriction, of incorporating a part fixturing design approach, distinguishes this research from F. S. D. Dymond’s work, who addressed the same problem while restricted to a fixtureless assembly approach. A conceptual layout design was developed to address part feeding, manipulation, transportation, fixturing and welding requirements, for an entire breaker model range. A simulation model for three possible layouts of the selected conceptual design provided a means to investigate each layout’s ability to tolerate and balance variation in production requirements, and to establish objective comparative performance data. This showed that the optimal configuration consists of four single loop layout systems. The thesis concludes that the final concept possesses the flexibility to produce the primary product range. Reconfiguration for production beyond this range is assisted by the modular nature of the layout. Ultimately, a reconfigurable design should focus on a properly selected base of core product ranges, providing an expandable and reusable system. The system can be supported by manual assembly stations which handle highly variant, incompatible product ranges.

The development of a system that emulates percussion to detect the borders of the liver

Rauch, Hanz Frederick 03 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009. / Percussion is a centuries old bedside diagnostic technique that is used to diagnose various conditions of the thorax and abdomen, among these, abnormalities of the liver. The physician taps the patient’s skin in the area of interest to determine the qualities or presence of the underlying tissue or organ, by listening to the generated sound. The research contained in this thesis views percussion as a system identification method which uses an impulse response to identify the underlying system. A design employing an electromagnetic actuator as input pulse generator and accelerometer as impulse response recorder was motivated and built. Tests were performed on volunteers and the recorded signals were analysed to find methods of identifying the presence of the liver from these signals. The analyses matched signals to models or simply extracted signal features and matched these model parameters or signal features to the presence of the liver. Matching was done using statistical pattern recognition methods and the true presence of the liver was established using MR images. Features extracted from test data could not be matched to the presence of the liver with sufficient confidence which led to the conclusion that either the test, apparatus or analysis was flawed. The lack of success compelled a further test on a mock-up of the problem – a silicone model with an anomaly representing the organ under test. Results from these tests showed that signals should be measured further from the actuator and the approach followed during this test could lead to the successful location of the anomaly and discrimination between subtle differences in the consistency thereof. It is concluded that further research should aim to first validate percussion as performed by the physician and increase complexity in a phased manner, validating results and apparatus at each step. The approach followed was perhaps too bold in light of the lack of fundamental understanding of percussion and the underlying mechanisms.

Wireless physiological monitoring system for psychiatric patients

Rademeyer, A. J. 12 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--Stellenbosch University, 2008. / This thesis is concerned with the development and testing of a non-invasive device that is unassailable, and can be placed on an aggressive psychiatric patient to monitor the vital signs of this patient. Two devices, a glove measuring oxygen saturation and another on the dorsal part (back) of the patient measuring heart rate via electrocardiography (ECG), skin temperature and respiratory rate were designed and implemented. The data is transmitted using wireless technology. Both devices connect to one central monitoring station using two separate Bluetooth connections ensuring a total wireless setup. All the hardware and software to measure these variables have been designed and implemented. A Matlab graphical user interface (GUI) was developed for signal processing and monitoring of the vital signs of the psychiatric patient. Detection algorithms were implemented to detect ECG arrhythmias such as premature ventricular contraction and atrial fibrillation. The prototype was manufactured and tested in a laboratory setting on five volunteers. Satisfactory test results were obtained and the primary objectives of the thesis were fulfilled

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