<p dir="ltr"> The general design goal of low latency communication systems is to minimize the end-to-end delay while attaining the predefined reliability and throughput requirements. The burgeoning demand for low latency communications motivates a renewed research interest of the tradeoff between delay, throughput, and reliability. In this dissertation research, we consider slotted-based systems and explore the potential advantages of the so-called sequential codes in low latency network communications.</p><p dir="ltr"> The first part of this dissertation analyzes the exact error probability of random linear streaming codes (RLSCs) in the large field size regime over the stochastic independently and identically distributed (i.i.d.) symbol erasure channels (SECs). A closed-form expression of the error probability <i>p</i>_<em>e</em> of large-field-size RLSCs is derived under, simultaneously, the finite memory length α and decoding deadline Δ constraints. The result is then used to examine the intricate tradeoff between memory length (complexity), decoding deadline (delay), code rate (throughput), and error probability (reliability). Numerical evaluation shows that under the same code rate and error probability requirements, the end-to-end delay of RLSCs is 40-48% of that of the optimal block codes (i.e., MDS codes). This implies that switching from block codes to streaming codes not only eliminates the queueing delay completely (which accounts for the initial 50% of the delay reduction) but also improves the reliability (which accounts for the additional 2-10% delay reduction).</p><p dir="ltr"> The second part of this dissertation focuses on the asymptotics of the error probability of RLSCs in the same system model of the first part. Two important scenarios are analyzed: (i) tradeoff between Δ and <i>p</i>_<em>e</em> under infinite α; and (ii) tradeoff between α and <i>p</i>_<em>e</em> under infinite Δ. In the first scenario, the asymptote of <i>p</i>_<em>e</em>(Δ) is shown to be <i>ρ</i>Δ^-1.5<i>e</i>^-^<em>η</em>^Δ. The asymptotic power term Δ^-1.5 of RLSCs is a strict improvement over the Δ^-0.5 term of random linear block codes. A pair of upper and lower bound on the asymptotic constant <i>ρ</i> is also derived, which are tight (i.e., identical) for one specific class of SECs. In the second scenario, a refine approximation is proposed by computing the parameters in a multiterm asymptotic form, which closely matches the exact error probability even for small memory length (≈ 20). The results of the asymptotics can be further exploited to find the <i>c</i>-optimal memory length <i>α</i>_<em>c</em>^*(Δ), which is defined as the minimal memory length α needed for the resulting <i>p</i>_<em>e</em> to be within a factor of <i>c</i>>1 of the best possible <i>p</i>_<em>e</em>^<em>*</em>_{<em> </em>}for any Δ, an important piece of information for practical implementation.</p><p dir="ltr"> Finally, we characterize the channel dispersions of RLSCs and MDS block codes, respectively. New techniques are developed to quantify the channel dispersion of sequential (non-block-based) coding, the first in the literature. The channel dispersion expressions are then used to compare the levels of error protection between RLSCs and MDS block codes. The results show that if and only if the target error probability <i>p</i>_<em>e</em> is smaller than a threshold (≈ 0.1774), RLSCs offer strictly stronger error protection than MDS block codes, which is on top of the already significant 50% latency savings of RLSCs that eliminate the queueing delay completely.</p>

Abstract is in English, Zulu and Afrikaans / South Africa is facing a challenge regarding the shortage of South African (SA) engineers. The National Certificate (Vocational) (NC(V)) was introduced by Department of Education (DoE) in 2007 to address this challenge. However, there has been a cry and dissatisfaction from the government, industry, community and other stakeholders that NC(V) engineering curriculum is not addressing the shortage of engineers. SA has one engineer per 2 600 people compared to international norms, where one engineer serves 40 people. It has been ten years since the introduction of NC(V) curriculum, SA should not be in this state of importing engineers if the NC(V) engineering is achieving the goals of National Development Plan 2030. Since lecturers are the implementers of the NC(V) engineering curriculum, it was necessary to investigate their experiences in search for improvement of the curriculum and to find out the challenges facing lecturers which are hindering the success of this curriculum. Lecturers, Senior Lecturers and a Head of Department (HoD) as the primary implementers of the engineering curriculum were involved in the study as participants. There were 15 participants for this study who are lecturing in one selected college but at two different campuses which is why the qualitative research approach was employed, making use of a multiple case study. They took part in semi-structured individual interviews and shared their experiences with the researcher. Their experiences revealed that lecturers are experiencing challenges with the implementation of NC(V) engineering curriculum. Their main challenge was the minimum requirement, which is a Grade 9 pass. Their concern was that no matter what they try, a learner who has not mastered Mathematics up to Grade 12 will struggle with engineering subjects. Emanating from this challenge, low attendance rate, low pass rate, low throughput rate and high drop-out rate is experienced by participants every year. One of the aims of the Transformative Learning Theory (used as one of the theories in the theoretical framework) is to allow lecturers to identify challenges and design improvement plans on their own. This study has indicated that Technical Vocational Education and Training (TVET) colleges have challenges that are hindering teaching and learning. It was evident that some lecturers believe that government officials should resolve such challenges. However, on engaging with different lecturers they realised that they have the capacity to address classroom-based challenges. If this can be the case in every college, teaching and learning will improve because that will mean lecturers are focusing on teaching and learning and taking ownership of their subjects and students. The governance challenges, such as reviewing the NC(V) curriculum yearly, provide subject specific training to upskill lecturers and implementing Work Integrated Learning (WIL) in the professional development of lecturers were recommended to be addressed by the Department of Higher Education and Training (DHET). / INingizimu Afrika ibhekene nenselelo mayelana nokusweleka konjiniyela. Uhlelo lwemfundo iNational Certificate (Vocational) (NC(V)) lwethulwa wuMnyango wezeMfundo ngonyaka ka 2007 ukuze uxazulule le nkinga. Yize-kunjalo kuye kwaba khona ukungagculiseki ngasohlangothini lukahulumeni, lwezimboni, lomphakathi kanye nakwezinye izinhlaka ezidlala indima yenkinga yokuntuleka konjiniyela. INingizimu Afrika (SA) inonjiniyela oyedwa kubantu abayi 2 600 uma iqhathaniswa nezinga lomhlaba lokuthi unjiniyela oyedwa kufanele ibhekane nabantu abayi 40. Sekudlule iminyaka eyishumi selokhu kwethulwa lezi zinhlelo, ngakho-ke, iSA akufanele izithole isesimeni sokudinga onjiniyela abavela ngaphandle uma ngabe izinhlelo ezikhona ziyanceda ekufinyeleleni izimpokophelo zoHlelo lwezokuThuthukisa iZwe National Development Plan 2030. Njengoba abafundisi bangabaqhubi bezinhlelo zobunjiniyela, phecelezi NC(V), nokho sasikhona isidingo sokuphenya lokho abahlangabezana nakho ukuze kuthuthukiswe izinhlelo futhi kuvunjululwe izinselele ezibhekene nabafundisi, okuyizinselele ezikhinyabeza impumelelo yalezi zinhlelo. Abafundisi, abafundisi abaphezulu kanye neziNhloko zoMnyango Head of Department (HoD) njengabaqhubi bokuqala bezinhlelo bebebambe iqhaza kulolu cwaningo. Abadlalindima abayi 15 bebefundisa kwikholeji ekhethiwe, kodwa emagatsheni amabili ehlukene, lokho okwenza isizathu kusetshenziswe uhlelo locwaningo oluzinze kwizingxoxo, ngokusebenzisa izinhlobonhlobo zocwaningo lotho. Kwenziwe izinhlolovo ezimbaxambili zocwaningo kanti abadlalindima bavezele umcwaningi ulwazi lwabo. Baye baveza ukuthi behlangabezene nezingqinamba uma besebenzisa izinhlelo zobunjiniyela NC(V). Inselele enkulu abahlangabezene nayo kuye kwaba yisidingo sokuphumelela uGreyidi 9. Inkinga enkulu yabo ukuthi bethi bezama ngamandla kulokho abakwenzayo, umfundi owehluleke esifundweni seMethamethiki ukufikela kuGreyidi 12 uzohlangabezana nobunzima ukuze aphumelele ezifundweni zobunjiniyela. Okubhebhethekiswa yile nselele, yizinga eliphansi labafundi abahambela lesi sifundo, izinga eliphansi labafundi abaphumelelayo kanye nezinga eliphezulu labafundi abayeka ukufunda njalo nje ngonyaka. Enye yezinhloso zethiyori yemfundo eguqulayo (used as one of the theories in the theoretical framework) ukuvumela abafundisi ukuba bakwazi ukubona izinselele futhi badizayine izinhlelo zokuzithuthukisa ngokwabo. Lolu cwaningo luye lwaveza ukuthi amakholeji. Phecelezi Vocational Education and Training (TVET) colleges ahlangabezene nezinselele eziphazamisa uhlelo lokufunda nokufundisa. Kuye kwacaca ukuthi abanye abafundisi babekholelwa ekutheni abasebenzi bakahulumeni kufanele baxazulule izinselele ezinjengazo lezi. Yize-kunjalo, ngemuva kokuxoxisana nabafundisi abahlukahlukene, baye bazwisisa ukuthi banamandla okuqeda izinselele ezisemagunjini okufunda. Uma ngabe lokhu kuyenzeka ngempela kuwo wonke amakholeji, ngakho-ke uhlelo lokufunda nokufundisa luzothuthuka ngoba lokho kuzochaza ukuthi abafundisi bagxile ohlelweni lokufunda nokufundisa kanti ngokunjalo baba yibo abalawula izifundo kanye nabafundi babo. Izinselele zokuphatha, ezinjengokubuyekezwa kohlelo lwemfundo, phecelezi NC(V) njalo nje ngonyaka, lunikeza ukuqeqeshwa okuthile okuthuthukisa abafundisi. Ukulandela uhlelo lwemfundo oluhlangene nomsebenzi olumayelana nokuthuthukiswa ngokomsebenzi wabafundisi kuyinto enconywe ukuba ilungiswe uMnyango weMfundo ePhakeme kanye nokuQeqeshwa (Department of Higher Education and Training). / ʼn Tekort aan ambagslui staar Suid-Afrika in die gesig. Om hierdie rede het die Departement van Onderwys in 2007 die Nasionale Sertifikaat (Beroepsgerig) (NS(B)) ingestel. Tot die ontevredenheid van die regering, die bedryf, die gemeenskap en ander belanghebbendes vul hierdie kurrikulum nie die tekort aan nie. In Suid-Afrika is daar een ambagspersoon vir elke 2 600 mense teenoor die internasionale norm van een ambagspersoon per 40 mense. Hierdie kurrikulum is meer as tien jaar gelede ingestel en SA moet tans ambagslui invoer. Die oogmerke van die Nasionale Ontwikkelingsplan 2030 word dus nie verwesenlik nie. Aangesien dosente die NS(B) kurrikulum vir werktuigkundiges implementeer, moes hulle belewenisse ondersoek en hulle probleme bepaal word om die kurrikulum te verbeter. Dosente, senior dosente en departementshoofde, as die implementeerders van hierdie kurrikulum, het aan die studie deelgeneem. Die 15 deelnemers is verbonde aan een kollege wat twee kampusse het. Daarom is ʼn kwalitatiewe navorsingsbenadering gevolg en ʼn veelvuldige gevallestudie gebruik. ʼn Halfgestruktureerde onderhoud is met elke deelnemer gevoer. Uit die onderhoude blyk dat dosente moeite met die implementering van die NS(B) kurrikulum ondervind. Die grootste struikelblok is die minimumvereiste van Graad 9. Al doen hulle ook wat, ʼn leerder wat nie Graad 12-wiskunde geslaag het nie, sal tegniese vakke nie kan bemeester nie. Afgesien hiervan is die bywonings- en slaagsyfer sowel as die omset jaar na jaar laag en die uitsaksyfer hoog. Die transformatiewe leerteorie is deel van die teoretiese raamwerk. Die oogmerk hiervan is dat dosente self probleme aantoon en met verbeteringsplanne kom. In hierdie studie is bevind dat kolleges vir tegniese beroepsgerigte onderwys en opleiding (TBOO) met probleme te kampe het wat onderrig en leer belemmer. Sommige dosente is van mening dat staatsamptenare hierdie probleme moet oplos. Ná gesprekke het talle dosente egter besef dat hulle oor die vermoë beskik om self hulle klaskamerprobleme op te los. As dit van alle kolleges waar is, sal onderrig en leer verbeter omdat dosente hulle op onderrig en leer sal toespits en vir hulle vakke en studente verantwoordelik sal wees. Vakopleiding word gegee om aan bestuursprobleme, soos die jaarlikse hersiening van die NS(B)-leerplan, die hoof te bied. Daar word aanbeveel dat die Departement van Hoër Onderwys en Opleiding toesien dat werkgeïntegreerde leer deel uitmaak van dosente se professionele ontwikkeling. / Curriculum and Instructional Studies / M. Ed. (Curriculum Studies)

<p>This ethnographic project delves into the spheres of life of three autistic adults and their families. This thesis analyzes their experiences, current routines, and personal and family narratives about what it means to be an autistic adult across different identities and geographies. This thesis also identifies forms of knowledge that arise in these life experiences and shape strategies, decisions, or attitudes taken to navigate through life or overcome possible difficulties in their present and futures. This research takes place in Colombia, a diverse country and engages with anthropology of the everyday, sensory anthropology and disability studies.</p>

Introduction : L’utilisation des méthodes anatomiques classiques rend difficile la localisationprécise des micro-fibres nerveuses et ne permet pas de déterminer leur nature ni leur fonction.La chirurgie pelvienne est associée à des séquelles urinaires et sexuelles fréquentes causéespar lésion iatrogène des nerfs pelviens. La connaissance de l’anatomie et de la physiologie del’innervation intra-pelvienne est fondamentale pour tenter de réduire le taux de troublesfonctionnels postopératoires.Objectifs : i) étudier l’anatomie topographique et la nature de fibres nerveuses intrapelvienneen utilisant la reconstruction tridimensionnelle des coupes histologiques immunomarquéesii) standardiser la technique de Dissection Anatomique Assistée par Ordinateur(DAAO) et vérifier sa faisabilité sur des sujets adultes et iii) établir grâce à cette technique deDAAO des modèles pédagogiques tridimensionnels afin d’améliorer la compréhension desdysfonctions sphinctériennes et sexuelles survenant après la chirurgie (rectale et prostatique)et d’adapter éventuellement la technique opératoire.Matériel et méthodes : Des coupes histologiques sériées de pelvis ont été réalisées chez septfoetus masculins, sept foetus féminins et six cadavres adultes masculins. Les coupes ont ététraitées par des méthodes histologiques (Hématoxyline-Eosine et trichrome de Masson) etimmuno-histochimiques pour détecter les fibres nerveuses (anti-S100), les fibres somatiques(anti-PMP22), les fibres adrénergiques (anti-TH), cholinergiques (anti-VAChT), sensitives(anti-SP/CGRP) et nitrergiques (anti-nNOS) ainsi que l’actine lisse des sphincters. Les lamesont ensuite été numérisées par un scanner de haute résolution optique et les imagesbidimensionnelles ont été reconstruites en trois dimensions grâce au logiciel WinSurf.Résultats: La reconstruction tri-dimensionnelle des coupes histologiques immuno-marquéesa permis d'identifier l’anatomie topographique et structurelle de l’innervation intra-pelvienne.Les structures nerveuses afférentes du plexus hypogastrique inférieur (PHI) : nerfssplanchniques pelviens (NSP) et nerfs hypogastriques (NH) véhiculent de façon mixte l’influxsympathique et parasympathique pelvien.Les fibres nerveuses issues de la partie distale du PHI sont responsables de la continenceurinaire et de la fonction sexuelle. Elles sont regroupées et associées au pédicule vasculairepour former la bandelette neuro-vasculaire (BNV). Trois efférences principales sont issues decette BNV : i) des fibres antérieures destinées au sphincter urétral, ii) des fibres antérolatérales,par rapport à la prostate et au vagin, constituant le nerf caverneux destiné aux corpscaverneux du pénis/clitoris et iii) des fibres nerveuses postéro-latérales, par rapport à laprostate et au vagin, formant le « nerf spongieux » destiné aux corps spongieux/bulbesvestibulaires.Les communications autonomiques-somatiques entre le PHI supra-lévatorien et le nerfpudendal infra-lévatorien existent à trois niveaux ; proximal, intermédiaire et distal. Lacommunication distale caverno-pudendale est responsable de l’activité érectile segmentaireobservée au sein du nerf dorsal du pénis/clitoris.Conclusion: La DAAO est une méthode originale de recherche anatomique qui a étéprogressivement améliorée au sein de notre unité de recherche. Cette évolution illustre le faitque l'anatomie descriptive est encore une science dynamique. Notre étude a permis dedévelopper des modèles anatomo-physiologiques d’innervation pelvienne contribuant àaméliorer du point de vue morphologique, chirurgical et pédagogique la compréhension derégions anatomiques complexes comme le petit bassin. / Introduction: Classic anatomical methods have limitations in micro determination of nervefibre location. Furthermore, the precise detection of the nerve fibres nature is not possible bymeans of dissection. Pelvic surgery is associated with urinary and sexual consequence causedby iatrogenic damage of the pelvic nerves. Anatomic and physiologic knowledge of the intrapelvicinnervation is essential to reduce the rate of postoperative functional complication.Objectives: i) to study the topographic anatomy and the nature of intra-pelvic nerve fibersusing three-dimensional reconstruction of histological immuno-labeled sections ii)standardize the technique of Computer-Assisted Anatomic Dissection (CAAD) and check itsfeasibility on adult subjects iii) reconstructe three dimensional teaching models to improveunderstanding of urinary and sexual dysfunction occurring after surgery (of rectal and ofprostate) to ameliorate the operative technique.Materials and methods: serial histological sections of pelvic portion were performed inseven male foetuses, seven female foetuses and six adult male cadavers. The sections weretraited by histological methods (Hematoxylin-Eosin and Masson's trichrome) and immunohistochemicalmarker of the nerve fibers (anti-S100), the somatic fibers (anti-PMP22), theadrenergic (anti-TH), cholinergic (anti-VAChT), sensory (anti-SP/CGRP) and nitrergic (antinNOS)fibers and the actin smooth muscles. The slides were then digitized by a scanner ofhigh optical resolution and two-dimensional images were reconstructed in three dimensionsusing WinSurf software.Results: The three dimensional reconstruction of histological immuno-labelled sectionsidentified structural and topographic anatomy of intra-pelvic innervation. The afferencenerves of the inferior hypogastric plexus (IHP): pelvic splanchnic nerves (PSN) andhypogastric nerves (HN) contain both sympathetic and parasympathetic fibers.The nerve fibers from the distal part of the IHP is responsible for urinary continence andsexual function. They are grouped and associated with the vascular pedicle to form theneurovascular bundles (NVB). Efferences of this NVB are distributed in three maindirections: i) anterior fibers the urethral sphincter, ii) anterolateral fibers, compared withprostate / vagina, which constitute the cavernous nerve for the corpora cavernosa of the penis/ clitoris and iii) " spongious nerve”, which is the continuity of posterior-lateral nerve fibers,compared with prostate / vagina, for the corpus spongiosum / vestibular bulbs.Autonomic-somatic communications between supra-lavator IHP and infra-levator pudendalnerve are present at three levels; proximal, intermediate and distal communications. Cavernopudendaldistal communication provides segmental erectile activity of the dorsal nerve of thepenis / clitoris.Conclusion: The CAAD is an original method in anatomical research which has beenprogressively improved. This illustrates the fact that descriptive anatomy is still a dynamicscience. Our study has developed anatomico-physiological models of intra-pelvic innervationcontributing to a better understanding of complex anatomical

On a réalisé la démonstration d'une commutation spatiale de données d'une entrée vers 64 sorties par voie tout optique. Les composants originaux utilises sont une matrice de modulateurs a puits quantiques multiples en technologie gaalas a 64 éléments et une structure bistable optique de même technologie. Le principal résultat est le fonctionnement complet du démonstrateur voie par voie a la fréquence d'horloge de 20mhz (taux d'erreur inférieur a 1%). Les limitations viennent de la stabilité du laser et des non uniformités lors de la croissance epitaxiale des composants.

Magister Scientiae - MSc (Physics) / An increasing energy demand and growing environmental concerns regarding the use of fossil fuels in South Africa has led to the challenge to explore cheap, alternative sources of energy. The generation of electricity from Photovoltaic (PV) devices such as solar cells is currently seen as a viable alternative source of clean energy. As such, crystalline, amorphous and nanocrystalline silicon thin films are expected to play increasingly important roles as economically viable materials for PV development. Despite the growing interest shown in these materials, challenges such as the partial understanding of standardized measurement protocols, and the relationship between the structure and optoelectronic properties still need to be overcome.

Von Beginn der flexiblen Automatisierung mit numerisch gesteuerten Werkzeugmaschinen und der zugehörigen Programmier-Software bis zum gegenwärtigen Entwicklungsstand (Industrie 4.0) wird die historische Entwicklung von 1960 bis 2020 aus der Position eines aktiven Mitgestalters dargestellt. Interessanterweise vollzogen sich die wesentlichen Entwicklungsetappen für die ersten dreißig Jahre parallel in beiden deutschen Staaten. Aus den Lehren des Zweiten Weltkrieges wurden im Rahmen der UNESCO zum friedlichen Informationsaustausch geeignete wissenschaftliche Organisationen gegründet: • IFIP (Internationale Föderation für Informationsprozesse, speziell Arbeitsgrupp CAM • CIRP (Internationale Akademie der Fertigungstechniker) Mit der Berufung und aktiven Mitarbeit in diesen Organisationen war eine Plattform für die deutsch-deutsche und darüber hinaus internationale Kooperation gegeben. Ein besonderer Schwerpunkt für den geordneten Informationsaustausch im Rahmen der gesamten dynamischen Entwicklung im Gebiet der Produktionsautomatisierung war dabei die im 3-Jahres-Rhythmus durchgeführte Konferenzserie PROLAMAT (Programming Languages for Machine Tools), gestartet 1969 in Rom. Im weiteren Verlauf wurde dieser Begriff viel breiter für das gesamte Gebiet der automatisierten Informationsverarbeitung und Fertigung erweitert. Ein besonderer Höhepunkt war dabei die erfolgreichste PROLAMAT-Konferenz 1988 in Dresden. Parallel dazu erfolgten an der TU Dresden Entwicklungen in Richtung CAD/CAM-Labor und später CIM-TT (CIM-Technologietransferzentrum). Damit war an der TU Dresden 1989/90 ein Entwicklungsstand gegeben, der unmittelbar zu gemeinsamen deutsch-deutschen und internationalen EU-Projekten genutzt werden konnte. Dieses hohe Entwicklungsniveau wurde zur offiziellen Eröffnung des CIM-TT-Zentrums in den Eröffnungsreferaten durch den damaligen Wissenschaftsminister Dr. Riesenhuber und Ministerpräsident Prof. Biedenkopf gewürdigt. Durch die zum gleichen Zeitpunkt verfügte veränderte Nutzung des für das CIM-TT im Aufbau befindliche Gebäude durch die neugegründete Juristische Fakultät wurde der erfolgreich vorbereitete Weg verhindert. Unabhängig davon blieb meine fachliche Orientierung mit den gravierenden Weiterentwicklungen eng verbunden. Dazu trug das Sabbatical-Jahr in Norwegen und den USA 1992 maßgeblich bei. Mit dem Forschungsaufenthalt war die Entscheidungsvorbereitung für die vorgesehene Groß-Investition für das neueste generative Verfahren verbunden. Gleichzeitig mit dem fundierten Nachweis der bestgeeigneten sog. Rapid-Prototyping-Anlage vom deutschen Anbieter EOS München war die TU Dresden auf diesem neuen High-Tech-Gebiet 1992 in einer anerkannten Spitzenposition. Mit meiner Publikation eines der ersten Fachbücher im Gebiet Advanced Prototyping (jetzt Additiv Manufacturing) war darüber hinaus eine gute Basis für weitere innovative Aktivitäten gegeben Dazu gehört die Gründung einer High-Tech-Firma (SFM - Schnelle Fertigung von Modellen) mit bemerkenswerten beispielgebenden Ergebnissen. Hervorgehoben soll die zwanzigjährige aktive Kooperation mit der Universität Stellenbosch (RSA - Republik Südafrika), die unter anderem mit meiner Berufung zum Extraordinary Professor im Jahr 2003 verbunden ist. Mit der Eröffnung eines Technologie-Zentrums nach dem Vorbild des ursprünglichen CIM TT -Zentrums der TU Dresden konnte für Südafrika ein wertvoller Beitrag geleistet werden. Das gesamte Lebenswerk ist gekennzeichnet durch die Entwicklungsschritte von der Mathematisierung über die Algorithmierung bis hin zur Programmierung vielfältiger technologischer Sachverhalte. Die Ergebnisse sind in einer Anzahl von persönlichen Fachbüchern (z.T. übersetzt in das Russische und Ungarische) wie auch Konferenzberichten und mehr als 200 Veröffentlichungen (deutsch und englisch) dokumentiert.

The exact mechanism of the discharge in liquids ignition is not sufficiently known up to now. Although during the last years was achieved the great progress and overloading which some of them are written in this theoretical part of thesis. This thesis is divided into two experimental parts. When the first part deals with diagnostics of diaphragm discharge in electrolyte solutions and the second part is focused on its use for uncoiling (higher homogenization) of carbon nanotubes in solutions. In experiment 1, three different sized (4 l, 100 ml, 50 ml) diaphragm discharge configurations were used to diagnose diaphragm discharge in electrolyte solutions. Diagnostics is done through current and voltage waveforms with the addition of synchronized ICCD camera images that have been connected to a four-channel oscilloscope. The V-A characteristic can be described by three events occurring in the electrolyte solution with a gradual increase in voltage. Slowly increasing of the voltage in the solution leads first to electrolysis. The next phase is the formation of microbubbles or bubbles, which is characteristic of the curve by a slight decrease in the increase of the current passing between electrodes. The sudden increase in the current flow is characteristic of the last phase, namely the discharge phase. The distance of the electrodes from the diaphragm does not significantly affect the V-A characteristic. The higher diameter of the pin hole, therefore, has a higher voltage, but this does not affect the origin of bubble generation or breakdown. The higher thickness of diaphragm, the higher voltage is needed to the beginning of the bubbles generation, and consequently the discharge breakdown. Comparison of the voltage of the start generation of the bubbles and breakdown for PET diaphragms and diaphragms from the ceramic there was no mark able difference. One of the most important parameters is the conductivity of the electrolyte solution. The lower voltage is needed for the start generation of the bubbles at the higher solution conductivity, and also the discharge generation is observed at a lower breakdown voltage. The second experimental part is focused on the study of the diaphragm discharge effect on carbon nanotubes. A specially designed U-shaped reactor is used to modify carbon nanoparticles. Tap water and aqueous solutions of organic compounds are used as the electrolytic solutions. The discharge is generated by a non-pulsed DC high source with a voltage in the range of 0-2.8 kV supplied to platinum electrodes located in the electrolyte solution. The experimental results have shown that the diaphragm discharge has positive effects on the disintegration of clusters and agglomerates of carbon nanotubes. The primary effect on disintegration is probably the shock waves generated by the discharge. It turned out that it depends on the electrode configuration, where the treatment in anode space has far greater effects than the treatment in cathode half of the reactor. Effects of carbon nanotubes disintegration in solution are long-lasting and the treatment effect is not loosed after several months. There were detected no significant changes in the structure of plasma-treated nanotubes by Infra-red spectroscopy.

Different methods for the determination of cantilever properties in non-contact atomic force microscopy (NC-AFM) are under investigation. A key aspect is the determination of the cantilever stiffness being essential for a quantitative NC-AFM data analysis including the extraction of the tip-surface interaction force and potential. Furthermore, a systematic analysis of the displacement noise in the cantilever oscillation detection is performed with a special focus on the thermally excited cantilever oscillation. The propagation from displacement noise to frequency shift noise is studied under consideration of the frequency response of the PLL demodulator. The effective Q-factor of cantilevers depends on the internal damping of the cantilever as well as external influences like the ambient pressure and the quality of the cantilever fixation. While the Q-factor has a strong dependence on the ambient pressure between vacuum and ambient pressure yielding a decrease by several orders of magnitude, the pressure dependence of the resonance frequency is smaller than 1% for the same pressure range. On the other hand, the resonance frequency highly depends on the mass of the tip at the end of the cantilever making its reliable prediction from known cantilever dimensions difficult. The cantilever stiffness is determined with a high-precision static measurement method and compared to dimensional and dynamic methods. Dimensional methods suffer from the uncertainty of the measured cantilever dimensions and require a precise knowledge its material properties. A dynamic method utilising the measurement of the thermally excited cantilever displacement noise to obtain cantilever properties allows to characterise unknown cantilevers but requires an elaborative measurement equipment for spectral displacement noise analysis. Having the noise propagation in the NC-AFM system fully characterised, a proposed method allows for spring constant determination from the frequency shift noise at the output of the PLL demodulator with equipment already being available in most NC-AFM setups.