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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.
1

Motor aspects of binocularity

Bosman, Jeroen. January 2001 (has links)
Proefschrift Universiteit Maastricht. / Met lit. opg. - Met samenvatting in het Nederlands.
2

Development of a robust active infrared-based eye tracking system

Coetzer, Reinier Casper 18 July 2012 (has links)
Eye tracking has a number of useful applications ranging from monitoring a vehicle driver for possible signs of fatigue, providing an interface to enable severely disabled people to communicate with others, to a number of medical applications. Most eye tracking applications require a non-intrusive way of tracking the eyes, making a camera-based approach a natural choice. However, although significant progress has been made in recent years, modern eye tracking systems still have not overcome a number of challenges including eye occlusions, variable ambient lighting conditions and inter-subject variability. This thesis describes the complete design and implementation of a real-time camera-based eye tracker, which was developed mainly for indoor applications. The developed eye tracker relies on the so-called bright/dark pupil effect for both the eye detection and eye tracking phases. The bright/dark pupil effect was realised by the development of specialised hardware and near-infrared illumination, which were interfaced with a machine vision camera. For the eye detection phase the performance of three different types of classifiers, namely neurals networks, SVMs and AdaBoost were directly compared with each other on a dataset consisting of 17 individual subjects from different ethnic backgrounds. For the actual tracking of the eyes, a Kalman filter was combined with the mean-shift tracking algorithm. A PC application with a graphical user interface (GUI) was also developed to integrate the various aspects of the eye tracking system, which allows the user to easily configure and use the system. Experimental results have shown the eye detection phase to be very robust, whereas the eye tracking phase was also able to accurately track the eyes from frame-to-frame in real-time, given a few constraints. AFRIKAANS : Oogvolging het ’n beduidende aantal toepassings wat wissel van die deteksie van bestuurderuitputting, die voorsiening van ’n rekenaarintervlak vir ernstige fisies gestremde mense, tot ’n groot aantal mediese toepassings. Die meeste toepassings van oogvolging vereis ’n nie-indringende manier om die oë te volg, wat ’n kamera-gebaseerde benadering ’n natuurlike keuse maak. Alhoewel daar alreeds aansienlike vordering gemaak is in die afgelope jare, het moderne oogvolgingstelsels egter nogsteeds verskeie uitdagings nie oorkom nie, insluitende oog okklusies, veranderlike beligtingsomstandighede en variansies tussen gebruikers. Die verhandeling beskryf die volledige ontwerp en implementering van ’n kamera-gebaseerde oogvolgingsstelsel wat in reële tyd werk. Die ontwikkeling van die oogvolgingsstelsel maak staat op die sogenaamde helder/donker pupil effek vir beide die oogdeteksie en oogvolging fases. Die helder/donker pupil effek was moontlik gemaak deur die ontwikkeling van gespesialiseerde hardeware en naby-infrarooi illuminasie. Vir die oogdeteksie fase was die akkuraatheid van drie verskillende tipes klassifiseerders getoets en direk vergelyk, insluitende neurale netwerke, SVMs en AdaBoost. Die datastel waarmee die klassifiseerders getoets was, het bestaan uit 17 individuele toetskandidate van verskillende etniese groepe. Vir die oogvolgings fase was ’n Kalman filter gekombineer met die gemiddelde-verskuiwings algoritme. ’n Rekenaar program met ’n grafiese gebruikersintervlak was ontwikkel vir ’n persoonlike rekenaar, sodat al die verskillende aspekte van die oogvolgingsstelsel met gemak opgestel kon word. Eksperimentele resultate het getoon dat die oogdeteksie fase uiters akkuraat en robuust was, terwyl die oogvolgings fase ook hoogs akuraat die oë gevolg het, binne sekere beperkinge. Copyright / Dissertation (MEng)--University of Pretoria, 2012. / Electrical, Electronic and Computer Engineering / unrestricted
3

Gotiese elemente in Francois Bloemhof se debuutroman, Die nag het net een oog

Loots, Maria Johanna 03 1900 (has links)
Thesis (MA (Afrikaans and Dutch))—University of Stellenbosch, 2007. / In this thesis I examine the Gothic elements in François Bloemof’s debut novel, Die nag het net een oog (1991). There are two reasons this novel can be seen as an exemplary text in Afrikaans: firstly, it contributes to a genre of which there are very few examples in Afrikaans, namely the Gothic novel. Secondly, it leads to a reevaluation of texts of C.J. Langenhoven, C. Louis Leipoldt and Marius Gie (pseudonym of Martha C Gieseke). Apart from a discussion of the Gothic novel in general and specifically Bloemhof’s novel, this thesis also examines his large oeuvre, constant focus on renewal and his position in the Afrikaans literary system. The Gothic novel is generally regarded as a form of popular literature. This aspect, together with the history, function, development and characteristics of the Gothic novel, is also looked at in the thesis in an attempt to contribute to the minimal theoretization on this subject in Afrikaans. Lastly I will discuss the Gothic elements in Bloemhof’ s debut novel. Die nag het net een oog has many of the characteristics of the earlier Gothic novels, but Bloemhof renews them by crossing over conventional boundaries. The heroine being the rescuer instead of the rescuee, is one such example. The study is concluded with short summarizing comments and suggestions for further study.
4

Die gruwel en die Gotiese in drie hedendaagse tekste : Die nag het net een oog - Francois Bloemhof, Drif - Reza de Wet, Een hart van steen - Renate Dorrestein

Buys, Helga Minnette 03 1900 (has links)
Thesis (MA)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: This thesis contains the results of an investigation into the elements of the horror story and the Gothic novel in three contemporary works. The investigation was conducted within the theoretical framework of the original historical Gothic novel of the eighteenth century, in comparison with contemporary theorization on the Gothic, with specific reference to the study of Eddy Bertin, and to some extent Hendrik van Gorp and Fred Botting. Four conventions of the Gothic genre were identified, and were applied to an Afrikaans novel and drama, as well as a Dutch novel, to establish to which extent the Gothic manifests itself in these contemporary texts. The study focussed on The night only has one eye (1991) by Francois Bloemhof, Crossing/ Passion (1994) by Reza de Wet and A heart of stone (1999) by Renate Dorrestein. From these texts, which were read within a Gothic framework, it could be deduced that there is a deviation from the conventional Gothic texts within both the Afrikaans and the Dutch texts. This deviation especially occurs with regard to characterization, with specific reference to the female character. The authors use the traditional Gothic characters as a point of departure, but bring about renewal in the texts by making them part of a wider philosophical field. The portrayal of the themes of good versus evil, space and tension, also shows a deviation from the Gothic conventions. An important finding in this study is that the Gothic genre in its pure form can not successfully be traced in contemporary literature. The three texts under discussion show the occurrence of allogamy between the different sub-categories of horror. A further important conclusion is that these three texts cannot be merely categorized as Popular literature because of the renewal it brings regarding the traditional Gothic conventions. / AFRIKAANSE OPSOMMING: Hierdie tesis bevat die resultate van 'n ondersoek na elemente van die gruwelverhaal en die Gotiese roman in drie kontemporêre tekste. Die ondersoek is gedoen binne die teoretiese raamwerk oor die genre van die oorspronklike historiese Gotiese roman van die agtiende eeu, in vergelyking met die hedendaagse teoretisering oor die Gotiek, met spesifieke verwysing na die navorsing van Eddy Bertin, en in 'n mindere mate Hendrik van Gorp en Fred Botting. Vier konvensies van die Gotiese verhaaltipe is geïdentifiseer en toegepas op 'n Afrikaanse roman en drama, asook 'n Nederlandse roman, om vas te stel in watter mate en op watter wyse die Gotiek gemanifesteer word in dié hedendaagse tekste. Die navorsing fokus op Die nag het net een oog (1991) van Francios Bloemhof, Drif (1994) van Reza de Wet en Een hart van steen (1999) van Renate Dorrestein. Dié tekste vertoon al drie duidelik Gotiese kenmerke, maar vertoon daarbyook opvallende afwykings van die tradisionele verskyningsvorme van die Gotiek. Dit geld veral vir karakterisering - meer spesifiek die vroulike karakter en die verhouding tussen die twee geslagte. Die outeurs gebruik die tradisionele Gotiese tipe karakters as vertrekpunt, maar bring vernuwing deur die tekste deel te maak van 'n wyer filosofiese veld. Die tekste se hantering van ander konvensies op die terrein van die tematiese (die goeie versus die bose), ruimte en spanning wyk ook af van die historiese Gotiek. 'n Belangrik aspek wat in die ondersoek na vore kom, is dat die Gotiek as verhaaltipe selde nog in sy suiwer vorm in literatuur aangetref word. Die drie tekste onder bespreking toon in watter aansienlike mate kruisbestuiwing plaasvind tussen die onderskeie sub-kategorieë van die riller. Laastens word daar aangevoer dat die Gotiese en gruwel-elemente binne dié drie tekste op so 'n vernuwende wyse geproblematiseer en uitgedaag word, dat dit nie sonder meer as triviaalliteratuur beskou kan word nie.
5

Exposure to hand-arm vibration and its effects on workers at a mine rock drill repair and maintenance workshop / D.P. Visagie.

Visagie, Daniël Petrus January 2012 (has links)
In many occupations, exposure to hand-transmitted vibration (HTV) over a prolonged period causes various disorders involving the vascular, neural and musculoskeletal systems, collectively known as the hand-arm vibration syndrome (HAVS). It is a complex and potentially disabling chronic disorder of the upper extremities, especially of the hands. Numbness, tingling, reduced tactile discrimination, and impaired manipulative dexterity are often reported by workers exposed to HTV. The precise pathophysiological mechanism responsible for vascular injuries in HAVS has not yet been fully clarified; it seems to be multifactorial and highly complex. Interaction of neural signals, hormones, mediators and changes in the blood vessel itself appear to contribute to the development of such vascular injuries. This study aims to assess the risk of the hand-transmitted vibration exposure during pneumatic impact wrench operation in a rock drill repair and maintenance workshop at a South African platinum mine. A total of 8 workers working on a day to day basis with impact wrenches were available for this study. For each of the workers a control (not exposed to vibration) was selected on the basis of gender, ethnic group, smoking habits, age and body mass index (BMI). Grip force, dexterity and hand-eye co-ordination were tested on the workers and control group before and after work. Finger systolic blood pressure (FSBP) was also measured after cold provocation of the worker and control groups. Results have shown astatistically significant difference between the two groups with respect coordination, dexterity and FSBP after cold provocation. Vibration measurements shows three workers had values above the suggested ELV of 5 m/s² for an eight hour A (8) workday. With regards to dexterity, workers were capable to manipulate small objects better with their dominant right (vibration exposed) hand after work than before work. In contrast, it seems that the number of pegs correctly inserted by the controls is not uniformly affected by their 8 hour workday. The worker group showed a greater grip force than that of the control group, both before and after work.There was a statistically significant difference between the control and worker group with respect to the number of mistakes during the mirror trace and the time to complete this test only for the right hand. The difference in FSBP after cold provocation between the control and worker group observed is of medium importance when compared with effect sizes, however, there was no statistical significant difference. In this study, it was very difficult to make valid conclusions due to the limitations of a small sample size. A longitudinal study should be conducted preferably using newly appointed workers with no prior exposure to vibration and a sufficient control group to eliminate the effect other confounding variables such as general working conditions. / Thesis (MSc (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2013.
6

Exposure to hand-arm vibration and its effects on workers at a mine rock drill repair and maintenance workshop / D.P. Visagie.

Visagie, Daniël Petrus January 2012 (has links)
In many occupations, exposure to hand-transmitted vibration (HTV) over a prolonged period causes various disorders involving the vascular, neural and musculoskeletal systems, collectively known as the hand-arm vibration syndrome (HAVS). It is a complex and potentially disabling chronic disorder of the upper extremities, especially of the hands. Numbness, tingling, reduced tactile discrimination, and impaired manipulative dexterity are often reported by workers exposed to HTV. The precise pathophysiological mechanism responsible for vascular injuries in HAVS has not yet been fully clarified; it seems to be multifactorial and highly complex. Interaction of neural signals, hormones, mediators and changes in the blood vessel itself appear to contribute to the development of such vascular injuries. This study aims to assess the risk of the hand-transmitted vibration exposure during pneumatic impact wrench operation in a rock drill repair and maintenance workshop at a South African platinum mine. A total of 8 workers working on a day to day basis with impact wrenches were available for this study. For each of the workers a control (not exposed to vibration) was selected on the basis of gender, ethnic group, smoking habits, age and body mass index (BMI). Grip force, dexterity and hand-eye co-ordination were tested on the workers and control group before and after work. Finger systolic blood pressure (FSBP) was also measured after cold provocation of the worker and control groups. Results have shown astatistically significant difference between the two groups with respect coordination, dexterity and FSBP after cold provocation. Vibration measurements shows three workers had values above the suggested ELV of 5 m/s² for an eight hour A (8) workday. With regards to dexterity, workers were capable to manipulate small objects better with their dominant right (vibration exposed) hand after work than before work. In contrast, it seems that the number of pegs correctly inserted by the controls is not uniformly affected by their 8 hour workday. The worker group showed a greater grip force than that of the control group, both before and after work.There was a statistically significant difference between the control and worker group with respect to the number of mistakes during the mirror trace and the time to complete this test only for the right hand. The difference in FSBP after cold provocation between the control and worker group observed is of medium importance when compared with effect sizes, however, there was no statistical significant difference. In this study, it was very difficult to make valid conclusions due to the limitations of a small sample size. A longitudinal study should be conducted preferably using newly appointed workers with no prior exposure to vibration and a sufficient control group to eliminate the effect other confounding variables such as general working conditions. / Thesis (MSc (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2013.

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