In the Master’s Thesis “Pre-investigation of Stormwater Quality at Metals Scrap Processing Plant” the literature review of 136 sources was performed with the focus on storm water pollution, physical and chemical properties of specific pollutants, origins of the pollution and pathways of the pollutants transport to the environment. Types of industrial storm water samples and sampling methodologies are described as well. Raprinfall data calculation are performed for the design of industrial storm water collection and treatment systems. The comprehensive analyses of storm water treatment are done. The experimental part of the work was carried out at the metal scrap processing industry with paved and unpaved aeries of the surfaces. During the research the industrial storm water screening characterisation was done at different locations of the whole territory. The treatment technology, including the sedimentation tank, retention tank and filtration trench was selected and calculated for the treatment of storm water of the investigated industry. The generalized conclusions and results of the work can be useful for state institutions, research institutions and the enterprises engaged in storm water management.

The separation of aqueous and organic mixtures with thermal separation processes is an important and challenging task in the chemical industry. Rising prices for energy, stricter environmental regulations and the increasing demand for high purity chemicals are the main driving forces to find alternative solutions to common separation technologies such as distillation and absorption. These are mostly too energy consumptive and can show limited separation performance, especially when applied to close boiling or azeotropic mixtures. Pervaporation can overcome these thermodynamic limitations and requires less energy because only the separated components need to be evaporated. This separation technology is already well established for the production of anhydrous solvents, but not yet widely distributed in the chemical and petrochemical industry due to some crucial challenges, which are still to overcome. Besides the need of high selective membranes, the development of membrane modules adapted to the specific requirements of organoselective pervaporation needs more research effort. Furthermore, only few modelling and simulation tools are available, which hinders the distribution of this process in industrial scale. In this work, these issues are addressed in a combined approach. In close collaboration with our cooperation partners, a novel membrane module for organophilic pervaporation is developed. A novel technology to manufacture high selective polymeric pervaporation membranes is applied to produce a membrane for an industrially relevant organic-organic separation task. A three step modelling approach ranging from a shortcut and a discrete to a rigorous model is developed and implemented in a user interface. A hydrophilic and an organophilic membrane are characterised for the separation of a 2-butanol/water mixture in a wide range of feed temperature and feed concentration in order to establish a generally valid description of the membrane performances. This approach is implemented in the three developed models to simulate the novel membrane module in industrial scale. The simulations are compared to the results of pilot scale experiments conducted with the novel membrane module. Good agreement between simulated and experimental values is reached.

Charakteristisch für Perlcellulose als Regenerat vom Typ Cellulose II sind sphärisch geformte, poröse Partikel mit einer hohen spezifischen Oberfläche und einer guten Bioverträglichkeit. Aufgrund ihrer Eigenschaften sind diese Cellulosemikropartikel besonders gut für medizinische Anwendungen geeignet. Im Mittelpunkt der Arbeit standen Herstellung, Charakterisierung und Modifizierung von Perlcellulosen mit Partikelgrößen von etwa 1 bis10 µm. Im Rahmen der Arbeit wurden zunächst sieben technische Cellulose-2,5-acetate mit vergleichbaren molekularen Eigenschaften auf ihre Eignung zur Herstellung von Perlcellulose nach dem in EP0750007 beschriebenen Acetatverfahren untersucht. Dabei erfolgte der Vergleich verschiedener Eigenschaften. Aus allen untersuchten Celluloseacetaten können Perlcellulosen synthetisiert werden. Als besonders geeignet erwies sich ein Produkt mit einer Molmasse von über 100.000, einem Verhältnis der Molmasse zur numerischen Molmasse von etwa 1,5 und einer guten Löslichkeit in Ethylacetat / Methanol (100:17,5). Die hergestellte Perlcellulose hat eine geringe Partikelgröße und eine relativ enge Größenverteilung. Damit erfüllt dieses Cellulose-2,5-acetat alle Anforderungen für die Synthese von Perlcellulose. Der entscheidende Verfahrensschritt zur Herstellung von Perlcellulose ist das Dispergieren der Emulsion mittels Inline-Ultraturrax. Die Partikelgrößenverteilung hängt im Wesentlichen von den Bedingungen während des Dispergierens ab. Im Rahmen der Arbeit gelang die reproduzierbare Herstellung von Cellulosemicrospheres mit einer Partikelgröße unter 5 µm. Für die Herstellung von Cellulosemikropartikeln mit definierten Eigenschaften ist neben den Synthesebedingungen auch die Charakterisierung der Perlcellulosen von entscheidender Bedeutung. Dafür wurden zunächst etablierte Verfahren verwendet (Partikelgrößenmessung, REM und Quecksilberporosimetrie). Parallel dazu erfolgte die Entwicklung bzw. Einführung neuer Methoden. Im Vordergrund stand die Untersuchung des Sedimentationsverhaltens der Perlcellulosen durch analytisches Zentrifugieren. Davon ausgehend konnte ein Verfahren zur Berechnung der Porosität aus dem Sedimentationsvolumen entwickelt werden. Zum Nachweis der kompletten Deacetylierung der Proben wurde die Ramanspektroskopie genutzt. Durch die Anwendung vorhandener und die Entwicklung neuer Methoden wird die genaue Einstellung von Eigenschaften der Perlcellulosen (z. B. Partikelgröße und deren Verteilung, Morphologie sowie Porosität) ermöglicht und deren Reproduzierbarkeit gewährleistet. Weitere Versuche hatten die Entwicklung von Endotoxinadsorbermaterial auf Basis von Perlcellulose und Polymyxin-B-sulfat (PMB) zum Ziel. Die Kopplung des PMB erfolgte meist nach Aktivierung der Proben mit Epichlorhydrin. Zunächst wurde die eingesetzte Epichlorhydrinmenge variiert, um das Optimum für die Aktivierung der Perlcellulosen zu finden. Weiterhin wurden unterschiedliche Mengen PMB angebunden und die Anbindung an nicht aktivierte Proben untersucht. Die Planung aller Versuche erfolgte jeweils nach Auswertung der an der Donau-Universität Krems durchgeführten Limulus- Amöbocyten- Lysat (LAL)-Tests. Mittels dieser Batchtests wurde die Wirksamkeit des Endotoxinadsorbermaterials sowohl im Vergleich zu unbehandeltem Blutplasma und als auch zu kommerziell erhältlichen Adsorbern auf Polystyrenbasis getestet. Endotoxinadsorber, die bei diesen Tests besonders gut bewertet wurden, konnten in einem up-scale- Versuch erstmals in größeren Mengen synthetisiert werden. Auch die direkte Herstellung von Endotoxinadsorbermaterial aus Perlcelluloseacetat konnte realisiert werden. Bei diesem neu entwickelten Verfahren erfolgen Deacetylierung und Aktivierung in einem Schritt. Damit kann die Herstellung vereinfacht werden. Zur Gewährleistung der Erstfehlersicherheit in extrakorporalen Blutreinigungssystemen sollen magnetisierte Perlcellulosepartikel als bioverträgliche Marker eingesetzt werden. Versuche zur Magnetisierung von Cellulosemikropartikeln während des Herstellungsprozesses zeigten, dass die Einbindung von Magnetit bei Erhalt der sphärischen Partikelstruktur prinzipiell auch auf diesem homogenen Syntheseweg möglich ist. / Bead cellulose is regenerated cellulose II characterized by spherically shaped, porous particles with a high specific surface and a good biocompatibility. Because of their properties these cellulose microspheres are especially suited for medical applications. The focus of this work was the synthesis, characterization and modification of bead cellulose with particle sizes between 1 to 10 µm. In the frame of this work seven technical cellulose-2.5-acetates were investigated with regard to their suitability for making bead cellulose according to the process described in EP0750007. These cellulose acetates have comparable molecular characteristics. Different properties were compared. Bead celluloses can be synthesized from all investigated cellulose acetates. A product with a molecular weight of more than 100,000 and with a ratio between molecular weight and numeric molecular weight of about 1.5 is special suited. This cellulose-2.5-acetate has a good solubility in ethyl acetate / methanol (100:17.5). The bead cellulose made from it has a low particle size and a relative narrow size distribution. Thus this cellulose acetate complies with the requirements for making bead cellulose. The most important process step for making bead cellulose is the dispersing of the emulsion using an inline-ultraturrax. The distribution of particle size depends mainly on the conditions during dispersing. A reproducible synthesis of cellulose microspheres with a particle size range below 5 µm was successfully achieved. In addition to determining conditions for manufacturing bead cellulose the characterization of the microspheres is essential to obtain bead cellulose with well defined properties. At first well-established methods of characterization were used (particle size measurement, SEM and mercury porosimetry). In parallel new methods were developed and implemented. The main focus was the investigation of sedimentation behaviour of bead cellulose using analytical centrifugation. Based on this knowledge of the sedimentation volume a new method to calculate the porosity was designed. Raman spectroscopy was used for detecting the complete deacetylation of the samples. By using well-established and newly developed methods properties of bead cellulose such as particle size and distribution, morphology and porosity can be accurately adjusted. In this way the reproducible synthesis of cellulose microspheres can be ensured. The aim of further experiments was to develop an endotoxin adsorber material based on a coupling of bead cellulose with Polymyxin B sulfate (PMB). The coupling with PMB was carried out after activation of the samples by using epichlorohydrin. At first the added epichlorohydrin amount was diversified in order to find the optimum for the activation of bead cellulose. Later the coupling of different amounts of PMB took place and the linking of PMB to non activated samples was investigated too. The planning of all experiments occurred after evaluation of Limulus amebocyte lysate (LAL) tests at Danube-University Krems. Using these batch tests the effectiveness of the endotoxin adsorber material was tested compared to untreated blood plasma as well as commercial available adsorbers based on polystyrene. Endotoxin adsorbers showing the best adsorption rate were then synthesized for the first time in larger quantities. Also the direct synthesis of endotoxin adsorber material based on bead cellulose acetate could be realized. Using this newly developed method, deacetylation and activation occur during the same step. This means manufacturing process can be simplified. Using magnetized bead cellulose as biocompatible marker particles is planned to achieve first fault safety in case of a membrane rupture during extracorporeal blood purification. Initial tests have shown that the magnetization of cellulose microspheres is possible during the manufacturing process. The incorporation of magnetite can be realized while keeping the spherical shape of the particles using this homogenous synthesis pathway.

Photovoltaic energy is the most promising future energy source. Therefore, strong efforts are made to improve their price-to-efficiency ratio. New technologies and materials are being involved in the production, such as poly-crystalline materials rather than mono-crystalline silicon. Some of these materials are based on copperchalcopyrite with advantageous properties like directly tunable band gap, high absorption coefficients, low deposition temperatures, low-cost materials and capability of deposition on suitable materials. However, correlation between the thin film materials characteristics and device performance are not well understood, and increasing the efficiency needs an exhaustive comprehension of the different phenomena involved in their performance, such as role of defects, doping concentrations and potentials, which requires the development of innovative techniques for the characterization. Electron holography in the TEM would be very helpful, because it allows the quantitative reconstruction of the complex object wave. The measurement of phase and amplitude of the wave makes it possible to determine the potential in the object studied. In this manner, electron holography is a powerful tool for materials characterization at nanometre scale because it relates potential distributions with structure. However, artefacts can be introduced in the measurement. Therefore, the procedure of acquisition, reconstruction and correction of artefacts of the electron holograms, fundamental for the interpretation of the results in terms of potential, are in detail presented. Moreover, the object of study exhibits challenges to the technique because of their polycrystalline structure, which introduces dynamic interaction with the electron beam sometimes stronger than the desired one. Consequently it is necessary to have an adequate measurement procedure. To overcome this limitation, a characterization method including in-situ stimuli is proposed and applied to crystalline silicon and CIGS solar cells. For this, a suitable sample preparation procedure with Focused Ion Beam (FIB) milling, and a specially designed sample holder allowing illumination with light and biasing a TEM sample are developed and applied to solar cells. As result of the work, it is shown that expectedly the electron illumination has an important influence. It produces larger generation rates than 1 sun standard illumination. As counterpart, the recombination processes occurring at the surface of the small and thin sample tend to reduce the potential generated by the illumination. As consequence, only the p-n junction potential is usually measured. To produce an appreciable effect by illumination with light, the TEM lamella must be thicker, and the illumination intensity of the light must be strongly increased. This thesis realises the first extensive study of the application of electron holography to the measurement of potentials in solar cells applying in-situ illumination and biasing. The experimental findings were corroborated by simulation calculations. They show that the processes in the objects are essentially correctly understood, however, quantitative interpretation is not yet sufficiently accurate. / Photovoltaik bietet eine vielversprechende Energiequelle der Zukunft. Deshalb werden große Anstrengungen unternommen, um ihr Preis-Nutzen-Verhältnis zu verbessern. Neue Technologien und Materialien, wie poly-kristalline Materialien werden interessanter als mono-kristallines Silizium. Einige dieser Materialien beruhen auf der Basis von Kupfer-Chalkopyrit mit vorteilhaften Eigenschaften, wie direkt einstellbarer Bandlücke, hohen Absorptionskoeffizienten, niedrigen Abscheidetemperaturen und Verwendung von Low-Cost-Materialien. Allerdings ist die Korrelation zwischen den Eigenschaften der Dünnschicht-Materialien und der Leistung der Solarzellen noch nicht ausreichend verstanden, um die Effizienz weiter zu steigern. Hierfür muss ein umfassendes Verständnis der verschiedenen Phänomene wie der Rolle von Defekten, Dotierungskonzentrationen und Potenzialen erreicht werden, die die Entwicklung von innovativen Techniken für die Charakterisierung erfordert. Elektronen-Holographie kann zur Beantwortung dieser Fragen beitragen, weil sie die quantitative Rekonstruktion der komplexen Objektwelle im TEM erlaubt. Die Messung der Phase und der Amplitude der Welle macht es möglich, die Objektpotentiale zu bestimmen. Auf diese Weise wird Elektronen-Holographie ein leistungsfähiges Werkzeug für die Materialcharakterisierung im Nanometerbereich, weil sie Struktur und Potentialverteilung an derselben Stelle bestimmen kann. Doch können Artefakte und Missinterpretationen entstehen. Daher sind Aufzeichnung von Elektronenhologrammen sowie Rekonstruktion und Korrektur der Objektwelle von grundlegender Bedeutung für die Interpretation der Ergebnisse und werden im Detail vorgestellt. Ein spezielles Problem von polykristallinen Materialien ist die Tatsache, dass durch unterschiedlich orientierte Kristallite unterschiedliche Innere Potentiale gemessen werden können. Darüber hinaus besteht die Gefahr, dass die Elektronen mit unterschiedlichen Körnern in unterschiedlicher Weise dynamisch wechselwirken; dies führt zu Phasendifferezen, die erheblich stärker sein können als die eigentlich interessanten Halbleiterpotentiale. Deshalb werden die holographischen Untersuchungen so modifiziert, dass die Objekte in-situ, beispielsweise unter Anlegen elektrischer Spannungen (“biasing”) oder Beleuchtung mit Licht, untersucht werden. Die hierzu nötigen neuen Präparationsverfahren für die Objekte werden entwickelt. Ebenso werden neue in-situ Objekthalter entwickelt, die diese Parameter gezielt zu verändern gestatten. Als Ergebnis der Arbeit wird auch gezeigt, dass die Elektronenbeleuchtung einen wichtigen Einfluss auf die gemessenen Potentialverteilungen hat. Sie produziert größere Generationsraten von Elektronen-Loch-Paaren als 1 sun (Standard-Beleuchtung). Tatsächlich werden durch Rekombinationsprozesse an der Oberfläche der Probe die induzierten Potentiale in der Solarzelle verringert. Als Folge wird in der Regel nur das Potenzial des pn-Übergang gemessen. Um eine spürbare Wirkung durch Bestrahlung mit Licht zu erzeugen, muss die TEM-Lamelle dicker gewählt werden, und die Beleuchtung muss wesentlich intensiver sein als unter normalbedingungen. Diese Dissertation realisiert die erste umfassende Studie über die Anwendung von Elektronen-Holographie für die Messung von Potenzialen in Solarzellen unter Anwendung von Biasing und in-situ-Beleuchtung. Die experimentellen Befunde wurden mit umfangreichen Simulationsrechnungen verglichen. Diese zeigen, dass die Vorgänge im wesentlichen qualitativ verstanden sind, auch wenn sie die gemessenen Potentialverteilungen quantitativ oft noch nicht mit der erwünschten Genauigkeit wiedergeben.

The thesis focuses on elastic polymer material that is biodegradable and compatible with human cells and tissues. The presented research describes polymer synthesis, material processing, physico-chemical investigation and biological tests performed on this novel biomaterial.

Η διασπορά κβαντικών τελειών ως πυρήνων αταξίας σε οργανωμένα συστήματα, έχει προσελκύσει επιστημονικό ενδιαφέρον και ερευνητικές δραστηριότητες, τόσο στο πεδίο της φυσικής στερεάς κατάστασης, όσο και σε αυτό της επιστήμης των υλικών. Δεν είναι σπάνια η διαπίστωση ότι υβριδικά συστήματα που προκύπτουν από συνδυασμούς όπως αυτός των υγρών κρυστάλλων και των νανοσωματιδίων, παρουσιάζουν αξιοσημείωτες και συχνά αναπάντεχες νέες ιδιότητες. Το θέμα της παρούσας διδακτορικής διατριβή κινείται σε δύο άξονες: το σχεδιασμό και την χημική σύνθεση κβαντικών τελειών επιφανειακά κατεργασμένων, για ελεγχόμενη αλληλεπίδραση με υγρούς κρυστάλλους, και τη μελέτη των φυσικών ιδιοτήτων των σύνθετων νανοδομημένων υγροκρυσταλλικών συστημάτων, που σχηματίζονται με διασπορά των νανοσωματιδίων αυτών σε χειρόμορφους θερμοτροπικούς υγρούς κρυστάλλους. Στο πρώτο μέρος της διατριβής παρουσιάζεται η χημική σύνθεση και επιφανειακή τροποποίηση κβαντικών τελειών CdSe, με υδρόφοβες επιφανειοδραστικές ομάδες τρι– οκτυλοφωσφίνης (TOP)/ελαϊκής αμίνης (ΟΑ), TOP/οκταδεκυλαμίνης, ΤOP/δωδεκυλα-μίνης, TOP/οκτυλαμίνης και τριφαινυλφωσφίνης/τριφαινυλαμίνης. Ο χαρακτηρισμός της δομής και των οπτικών ιδιοτήτων των νανοσωματιδίων έγινε με περίθλαση σκόνης ακτίνων Χ, φασματοσκοπία υπεριώδους–ορατού και φασματοσκοπία υπερύθρου, ενώ για τη διερεύνηση της μορφολογίας τους και τον προσδιορισμό των διαστάσεών τους, χρησιμοποιήθηκε ηλεκτρονική μικροσκοπία διέλευσης. Οι χημικές συνθέσεις, βασισμένες στην θερμολυτική διάσπαση οργανομεταλλικών ενώσεων, οδήγησαν σε επιτυχημένη παραγωγή σφαιρικών νανοσωματιδίων, μέσης διαμέτρου 3–4 nm, με στενή κατανομή μεγεθών και καλή διαλυτότητα σε οργανικούς διαλύτες. Στη συνέχεια μελετήθηκαν οι επιπτώσεις από τη διασπορά των νανοσωματιδίων CdSe με TOP και OA, με μέση διάμετρο 3.2 nm στη θερμοδυναμική και μοριακή οργάνωση χειρόμορφων υγρών κρυστάλλων, με τις τεχνικές της θερμιδομετρίας εναλλασσόμενης θερμικής εισόδου και με περίθλαση σκόνης ακτίνων Χ. Το ενδιαφέρον επικεντρώθηκε στη θερμοκρασιακή περιοχή των Μπλε φάσεων και στη μετάπτωση φάσης SmA–SmC*. Οι Μπλε φάσεις παρόλο που παρουσιάζουν εξέχουσες ιδιότητες για καινοτόμες εφαρμογές στη βιομηχανία οθονών και αισθητήρων, ωστόσο, είναι σταθερές σε πολύ στενά θερμοκρασιακά εύρη, μεταξύ Ισοτροπικής και Χειρόμορφης Νηματικής φάσης, γεγονός που δεν ευνοεί τη χρήση τους. Οι πειραματικές μετρήσεις αποκάλυψαν νέα φαινόμενα, όπως τη σταθεροποίηση της θερμοκρασιακής περιοχής της Μπλε φάσης ΙΙΙ (BPIII) σε μεγάλο θερμοκρασιακό εύρος, σε σχέση με τον αμιγή υγρό κρύσταλλο, και τη μετατόπιση των θερμοκρασιών μετάπτωσης σε μικρότερες τιμές. Η θεωρητική μελέτη που πραγματοποιήθηκε καταδεικνύει ισχυρή αλληλεπίδραση των νανοσωματιδίων με τις σειρές πλεγματικών ατελειών του υγρού κρυστάλλου. Παράλληλα τα αποτελέσματα φανερώνουν ότι ο χαρακτήρας Μέσου Πεδίου–Landau της μετάπτωσης SmA–SmC*, για το ίδιο σύστημα, δεν αλλοιώνεται. Η αλληλεπίδραση των κβαντικών τελειών CdSe με επιφανειακή δραστικοποίηση ΟΑ και TOP με χειρόμορφους υγρούς κρυστάλλους, παρέχει δυνατότητες και δημιουργεί σημαντικές προϋποθέσεις για νέες τεχνολογικές εφαρμογές και επιστημονικές εξελίξεις. / One dimensional semiconductor structures are intriguing materials for both fundamental research and industrial applications. On the other hand the long-range nature of the orientational order of liquid crystals is responsible for many fascinating optical, electromechanical and critical properties of these materials. Hybridization of these two fields may lead to novel materials with unusual optical and physical properties that are of considerable importance for technological applications as well as for basic physics studies on phase transitions and critical phenomena. In this context, complex soft materials were formulated that result from the dispersion of surface functionalized quantum dots in thermotropic chiral LCs. Special attention was paid to the synthesis and properties of the nanocrystals and to the dispersion state, as well as to the thermal and structural study of the composite materials. In the first part of this Thesis a chemical approach for the synthesis of semiconducting quantum dots is presented. The method, based on the thermolytic decomposition of organometallic compounds, leads to the production of spherical nanocrystalline particles highly soluble in organic media, with an average diameter of 3.2 nm, capped with a variety of amine and phosphine molecules. The as-synthesized nanoparticles were characterized by means of powder X-ray diffraction, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy and transition electron microscopy. The second part of the Thesis is concentrated on the effects upon the Blue phases and smectic-A to chiral smectic-C* phase transition of the liquid crystal CE8, arising from the dispersion of CdSe quantum dots, surface-treated with oleylamine and trioctylphosphine. For this purpose, ac calorimetry and X-ray scattering studies have been carried out. Liquid– crystalline blue phases exhibit exceptional properties for applications in the display and sensor industry. However, in single component systems, they are stable only for a very narrow temperature range between the isotropic and the chiral nematic phase, a feature that severely hinders their applicability. The systematic high-resolution calorimetric studies revealed that Blue phase III is effectively stabilized in a wide temperature range by mixing surface-functionalized nanoparticles with chiral liquid crystals. The calorimetric measurements also revealed substantial downshifts of the transition temperature. Theoretical arguments show that the aggregation of nanoparticles at disclination lines is responsible for the observed effects. Furthermore, it was found that at the SmA–SmC* phase transition, as a function of increasing nanoparticle concentration, the heat capacity anomalies display an extended-mean-field to mean-field–like crossover behavior, while the temperature dependence of the tilt angle remains bulk-like with no occurrence of pretransitional effects. The interaction of CdSe quantum dots with the cores of disclination lines gains further support, as bound disclination lines are expected to affect smectic–smectic phase transitions in a very limited manner.

Au cours de l’élaboration des peintures rupestres, divers matériaux colorants peuvent être mobilisés et produire des vestiges archéologiques liés aux différentes étapes de la préparation de la matière picturale. À Nawarla Gabarnmang, site majeur d’art rupestre Jawoyn (Terre d’Arnhem, Territoire du Nord – Australie), les fouilles archéologiques ont mis au jour un grand nombre de ce type de vestiges. La séquence archéologique, obtenue par datation au 14C, a révélé la présence de dépôts culturels parmi les plus anciens connus en Australie, avec une occupation du site qui s’étend de ≥48 000 ans cal BP jusqu’au début du XXème siècle. Plafonds et piliers du site présentent plusieurs générations de peintures ; les plafonds du site contiennent à eux seuls près de 1400 entités graphiques. La place de cet art interroge : est-il l’expression des premiers Hommes arrivés sur le continent australien il y a près de 50 000 ans ou le témoin d’occupations plus récentes ? Caractérisé par la superposition de plusieurs générations de peintures qu’on ne peut dater de manière « directe » en raison de la nature minéralogique des composants des peintures, la définition de leur chronologie constitue un fort enjeu de recherche. Menés d’emblée dans une approche intégrée, les premiers travaux ont permis d’étudier la chronologie et la nature des occupations, via les fouilles archéologiques, d’identifier les aménagements réalisés au cours des différentes phases d’occupation et de mettre en avant la richesse et la diversité de son répertoire artistique de même que l’abondance et la variété des vestiges associés à l’art rupestre. Afin d’appréhender au mieux la temporalité et les usages du site de Nawarla Gabarnmang depuis les premières occupations préhistoriques jusqu’aux fréquentations subactuelles, l’analyse des matières colorantes et colorées, retrouvées dans les carrés de fouille réalisés sous les panneaux peints des plafonds ou à l’aplomb des piliers décorés, permet de reconstituer les étapes de la chaîne opératoire ayant produit les matières picturales : de la source d’approvisionnement en matières premières, aux modes de transformation et de préparation (broyage, mélange avec charges et/ou liants, traitement thermique) jusqu’à leur application. La stratégie méthodologique mise en place couvre un large panel de techniques de caractérisation physico-chimique pour répondre aux problématiques soulevées par les différents vestiges associés à l’art rupestre. De l’observation macroscopique aux micro-analyses non invasives couplées à des analyses structurales, en passant par des techniques basées sur le rayonnement synchrotron, l’étude menée sur les matières colorantes et colorées a permis de révéler une diversité et une complexité de phases minérales utilisées dans l’art rupestre de Nawarla Gabarnmang. Croisée avec les données archéologiques, anthropo-géomorphologiques et pariétales, elle permet de proposer un cadre chronologique des différentes générations de peintures en lien avec les phases d’occupation qui ont marqué l’histoire du site. L’analyse des matières colorantes et colorées réalisée au cours de cette thèse constitue un vecteur de connaissances importantes et livre des informations complémentaires aux approches archéologique, géomorphologique et pariétale menées sur le site de Nawarla Gabarnmang. Les informations apportées par l’étude de ces matières permettent de renseigner tant sur les évolutions techniques et comportementales que sur l’implication culturelle de ce site, aussi bien dans ses dimensions spatiales que temporelles. / In the making of rock art, raw colouring material is used, thus providing many artifacts related to different steps of elaboration of pictorial matter. In the case of the important rock art site of Nawarla Gabarnmang in the Jawoyn country (Arnhem Land, North Territory – Australia), excavations have revealed a large number of such artifacts. The archaeological sequence from the floor deposits, radiocarbon-dated from ≥48,000 cal BP to the early twentieth century, has revealed some of the oldest known cultural deposits in Australia. The ceilings of the site contain well over 1400 still-visible paintings in multiple, superimposed layers. Countless additional paintings cover many of the rock pillars’ walls. This art raises questions: is it an expression of the first humans arrived on the Australian continent 50,000 years ago, or the evidence of recent occupation periods? Characterized by a succession of overlaid motifs, which cannot be “directly” dated because of the mineralogical nature of the rock paintings’ components, the determination of the age of the rock paintings represents a major issue. Through an integrated approach to the matter, the first results of the archaeological excavations enabled to study the chronology and the nature of activities, to identify the origins and transformations of the sheltered space through time, to highlight the richness and the diversity of its artistic work, as well as the abundance and the variety of the artifacts. To get a better insight into the temporality and the uses of Nawarla Gabarnmang since the first prehistoric activities until the recent periods, the analysis of the colouring and coloured matters, found in trial excavations under the painted panels on the ceilings or at the bottom of decorated pillars, allow us to rebuild the steps of the “chaîne opératoire” leading to the production of pictorial matter: from the sources of raw materials, the methods of transformation and preparation (grinding, mixing with mineral extenders and/or organic binders, heat treatment), to the application on the rock. To answer the questions raised by different artifacts, the methodological strategy includes a large range of microscopic and spectroscopic approaches. Subjected to macroscopic observations and non-invasive micro-analytical techniques along with structural techniques, as well as techniques using synchrotron radiation, the analysis of the colouring and coloured matters has revealed the variety and the complexity of mineral compounds used in the rock art of Nawarla Gabarnmang. Then, cross-referenced with archaeological, archaeomorphological and rock art studies, the physico-chemical characterization allows to suggest a chronological framework for the different superimposed layers linked to the periods of activities that marked the history of the site. The analysis of colouring and coloured matters undertaken by this thesis represents an important source of knowledge and delivers further informations to the geomorphological, archaeological and rock art studies carried out at the Nawarla Gabarnmang. The results provided by the study of these materials bring information as well on technical and behavioral evolutions, as on the cultural involvement of this site, not only in its spatial but also in its temporal dimensions.

Characterisation of modern complex powertrains is a time consuming and expensive process. Little effort has been made to improve the efficiency of testing methodologies used to obtain data for this purpose. Steady-state engine testing is still regarded as the golden standard, where approximately 90% of testing time is wasted waiting for the engine to stabilize. Rapid dynamic engine testing, as a replacement for the conventional steady-state method, has the potential to significantly reduce the time required for characterisation. However, even by using state of the art measurement equipment, dynamic engine testing introduces the problem that certain variables are not directly measurable due to the excitation of the system dynamics. Consequently, it is necessary to develop methods that allow the observation of not directly measurable quantities during transient engine testing. Engine testing for the characterisation of the engine air-path is specifically affected by this problem since the air mass flow entering the cylinder is not directly measurable by any sensor during transient operation. This dissertation presents a comprehensive methodology for engine air charge characterisation using dynamic test data. An observer is developed, which allows observation of the actual air mass flow into the engine during transient operation. The observer is integrated into a dual-ramp testing procedure, which allows the elimination of unaccounted dynamic effects by averaging over the resulting hysteresis. A simulation study on a 1-D gas dynamic engine model investigates the accuracy of the developed methodology. The simulation results show a trade-off between time saving and accuracy. Experimental test result confirm a time saving of 95% compared to conventional steady-state testing and at least 65% compared to quasi steady-state testing while maintaining the accuracy and repeatability of conventional steady-state testing.

Summary in English / The purpose of this research is to make a literary appreciation of the detective story in Tshivenda. Chapter 1 is the introductory chapter which discusses the aim of study, the definition of detective story, methodology, detective noels in Tshivenda, background information regarding the authors, summaries regarding selected novels and the scope of research. Chapter 2 is devoted to the plot structure of the two detective novels, and outlines the diegetic and meta-diegetic stories. The elements of mystery and dramatic irony are also discussed. Chapter 3 concentrates mainly on the setting of the two selected detective novels and its influence on the crimes committed, the lives of the characters and the tools that are used. Chapter 4 deals with the depiction of the victims, suspects and detectives in the selected detective stories. Chapter 5 concludes the study and summarises the main findings of the appraisal. / African Languages / M. A. (African Languages)

This study analyses the nature and implementation of electronic commerce in order to identify possible problems for taxation and pinpoint those problems which may be relevant to South Africa. Solutions suggested by certain countries and institutions are evaluated for possible implementation in South Africa. The study suggests that although current taxation legislation in South Africa is apP'icable to electronic commerce transactions it is not sufficient to cater effectively for this type of business. The conclusion reached Is that international co-operation is essential in finding solutions. A number of recommendations are made regarding aspects of South African taxation legislation which need to be clarified through policy decisions. Title of / Taxation / M.Comm.