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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.
311

X-Ray Near-Field Holography: Beyond Idealized Assumptions of the Probe

Hagemann, Johannes 16 August 2017 (has links)
No description available.
312

Narrative structure and the individual in the Íslendingasögur : motivation, provocation and characterisation

Shortt Butler, Joanne January 2016 (has links)
This thesis takes a fresh, character-based approach to the Íslendingasögur. It is inspired by a narratological study that unites the functional and structural role of characters with their human, individualistic portrayal. My major objective is to demonstrate the important connection between characterisation and structure in the sagas. By drawing attention to characters that I term narrative triggers, I offer a way of reading the sagas that relies both on the narrative conventions of tradition and on the less predictable, personal interactions between the cast of any given saga. In the case of both major and minor figures in the Íslendingasögur a certain type of character is often present to perform necessary motivational functions, allowing the plot to develop. In Part I I emphasise the functional aspect of these characters, before exploring unusual examples that emphasise their individuality in Part II.The motivation of the plot is linked throughout to the figure of the ójafnaðarmaðr. A secondary objective is to provide a clearer understanding of the nature and function of this commonly occurring character type. The ójafnaðarmaðr is frequently alluded to in scholarship,but this thesis provides the first in-depth study of the portrayal of these characters. The quality that informs them (ójafnaðr,‘inequity’, lit. ‘unevenness’) is a threat to one of the core values of saga society and hints at an ‘unbalancing’ of social interactions and of the narrative equilibrium itself. That this unbalance leads to changes in the social structure of the setting is a key factor in driving the plots of the sagas along. For this reason, a detailed examination of the figure of the ójafnaðarmaðr is long overdue: they can be observed to perform a specific narrative function but are always fitted to suit their particular context. Focussing on the structural conventions of character introduction, Part I establishes my methodology and catalogues the examples of characters introduced as ójafnaðarmenn. The scope is limited to those introduced as such because it allows me to establish for the first time the full corpus and conventions of these characters and their introductions. Following developments in our understanding of the oral background to the sagas, my approach to these narratives is built upon the evidence of their shared origins in pre-literate storytelling [...]. The intersection between functionality and individuality in character brings certain aspects of the Íslendingasögur to the fore. Part II of this thesis shows that in combination with the structural markers explored in Part I, the sagas employ the collective perspective of the general public, other characters and ‘irrational’ motivators such as fate to contribute to their techniques of characterisation. Because disruptive qualities speak inherently of a difference in the way an individual sees themselves and in the way the public sees them, or we as an audience are meant to see them, figures termed ójafnaðarmaðr are an ideal focal point for the development of this study.
313

Structural Characterization of III-V Bismide Materials Grown by Molecular Beam Epitaxy

January 2020 (has links)
abstract: III-V-bismide semiconductor alloys are a class of materials with applications in the mid and long wave infrared spectrum. The quaternary alloy InAsSbBi is attractive because it can be grown lattice-matched to commercially available GaSb substrates, and the adjustment of the Bi and Sb mole fractions enables both lattice constant and bandgap to be tuned independently. This dissertation provides a comprehensive study of the surface morphology and the structural and chemical properties of InAsSbBi alloys grown by molecular beam epitaxy. 210 nm thick InAsSbBi layers grown at temperatures from 280 °C to 430 °C on (100) on-axis, (100) offcut 1° to (011), and (100) offcut 4° to (111)A GaSb substrates are investigated using Rutherford back scattering, X-ray diffraction, transmission electron microscopy, Nomarski optical microscopy, atomic force microscopy, and photoluminescence spectroscopy. The results indicate that the layers are coherently strained and contain dilute Bi mole fractions. Large surface droplets with diameters and densities on the order of 3 µm and 106 cm-2 are observed when the growth is performed with As overpressures around 1%. Preferential orientation of the droplets occurs along the [011 ̅] step edges offcut (100) 1° to (011) substrate. The surface droplets are not observed when the As overpressure is increased to 4%. Small crystalline droplets with diameters and densities on the order of 70 nm and 1010 cm-2 are observed between the large droplets for the growth at 430°C. Analysis of one of the small droplets indicates a misoriented zinc blende structure composed of In, Sb, and Bi, with a 6.543 ± 0.038 Å lattice constant. Lateral variation in the Bi mole fraction is observed in InAsSbBi grown at high temperature (400 °C, 420 °C) on (100) on-axis and (100) offcut 4° to (111)A substrates, but is not observed for growth at 280 °C or on (100) substrates that are offcut 1° to (011). Improved crystal and optical quality is observed in the high temperature grown InAsSbBi and CuPtB type atomic ordering on the {111}B planes is observed in the low temperature grown InAsSbBi. Strain induced tilt is observed in coherently strained InAsSbBi grown on offcut substrates. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2020
314

Plasticity and damage mechanisms in specific multiphased steels with bainitic matrix under various mechanical loading paths : influence of temperature / Etude des mécanismes d'endommagement et de plasticité d'aciers multiphasés à matrice bainitique sous différents trajets de chagement : impact de la température

Martin, Pauline 14 November 2019 (has links)
Ce travail de thèse porte sur les mécanismes de plasticité et d'endommagement des aciers complexe-phase (CP). La microstructure bainitique de ces aciers, permets d’acquérir de bonnes propriétés de formabilité, qui intéressent les constructeurs automobiles. Cependant, la complexité de ces microstructures, qui se caractérisent par une grande quantité de joints de grains et une densité élevée de dislocations, influence la plasticité et les mécanismes d'endommagement. Afin d'estimer l'impact de la microstructure, une étude des caractéristiques métallurgiques des aciers à phases complexes est réalisée. Les mécanismes de plasticité sont ensuite étudiés par des tests de tension-compression afin d’étudier les mécanismes d’écrouissage du matériau. Ensuite, l’évolution de l’endommagement au sein de la microstructure est analysée à différente taux de triaxialité des contraintes afin d’obtenir la fraction de surface volumique ainsi que le nombre et le diamètre moyen des vides en fonction de la déformation plastique. Enfin, pour examiner la stabilité thermique de ces paramètres (microstructure, plasticité et endommagement), des expériences sont effectuées dans une plage de températures allant de 20 ° C à 600 ° C. / This PhD work investigates plasticity and damage mechanisms of complex phase steels. The bainitic microstructures of such steels, which feature retained austenite islands, result in these steels exhibiting good formability properties, which are of interest to automotive companies. However, the complexity of these microstructures, which are characterised by a high amount of grain boundaries and a high density of dislocations, influences plasticity and damage mechanisms. In order to estimate the impact of a steel's microstructure on these properties, the investigation of metallurgical features of complex phase steels provided by the company Faurecia is performed. Plasticity mechanisms are then investigated by tension-compression tests to determine the influence of long- and short-range interactions on the motion dislocation. Thereafter, the evolution of damage within microstructures is analysed at different stress triaxialities in order to obtain the volume area fraction and the number and average diameter of voids as functions of plastic strain. Finally, to examine the thermal stability of these parameters (microstructure, plasticity, and damage), experiments are performed at a range of temperatures between 20°C and 600°C.
315

Caractérisation et modélisation de la variabilité au niveau du dispositif dans les MOSFET FD-SOI avancés / Characterization and modelling of device level variability in advanced FD-SOI MOSFETs

Pradeep, Krishna 08 April 2019 (has links)
Selon l’esprit de la “loi de Moore” utilisant des techniques innovantes telles que l’intégration 3D et de nouvelles architectures d’appareils, le marché a également évolué pour commencer à imposer des exigences spécifiques aux composants, comme des appareils à faible consommation et à faible fuite, requis par l’Internet des objets (IoT) applications et périphériques hautes performances demandés par les applications 5-G et les centres de données. Ainsi, le secteur des semi-conducteurs s’est peu à peu laissé guider par les avancées technologiques, mais aussi par les applications.La réduction de la tension d’alimentation est encore plus importante pour les applications à faible puissance, comme dans l’IoT, cela est limité par la variabilité du périphérique. L’abaissement de la tension d’alimentation implique une marge réduite pour que les concepteurs gèrent la variabilité du dispositif. Cela nécessite un accès à des outils améliorés permettant aux concepteurs de prévoir la variabilité des périphériques et d’évaluer son effet sur les performances des leur conception, ainsi que des innovations technologiques permettant de réduire la variabilité des périphériques.Cette thèse se concentre dans la première partie et examine comment la variabilité du dispositif peut être modélisée avec précision et comment sa prévision peut être incluse dans les modèles compacts utilisés par les concepteurs dans leurs simulations SPICE. La thèse analyse d’abord la variabilité du dispositif dans les transistors FD-SOI avancés à l’aide de mesures directes. À l’échelle spatiale, en fonction de la distance entre les deux dispositifs considérés, la variabilité peut être classée en unités de fabrication intra-matrice, inter-matrice, inter-tranche, inter-lot ou même entre différentes usines de fabrication. Par souci de simplicité, toute la variabilité d’une même matrice peut être regroupée en tant que variabilité locale, tandis que d’autres en tant que variabilité globale. Enfin, entre deux dispositifs arbitraires, il y aura des contributions de la variabilité locale et globale, auquel cas il est plus facile de l’appeler la variabilité totale. Des stratégies de mesure dédiées sont développées à l’aide de structures de test spécialisées pour évaluer directement la variabilité à différentes échelles spatiales à l’aide de caractérisations C-V et I-V. L’effet de la variabilité est d’abord analysé sur des facteurs de qualité (FOM) sélectionnés et des paramètres de procédés extraits des courbes C-V et I-V, pour lesquels des méthodologies d’extraction de paramètres sont développées ou des méthodes existantes améliorées. Cette analyse aide à identifier la distribution des paramétres et les corrélations possibles présentes entre les paramètres.Ensuite, nous analysons la variabilité dépendante de la polarisation dans les courbes I-V et C-V. Pour cela, une métrique universelle, qui fonctionne quelle que soit l’échelle spatiale de la variabilité, est definée sur la base de l’analyse des appariement précédemment rapportée pour la variabilité locale. Cette thèse étend également cette approche à la variabilité globale et totale. L’analyse de l’ensemble des courbes permet de ne pas manquer certaines informations critiques dans une plage de polarisation particulière, qui n’apparaissaient pas dans les FOM sélectionnés.Une approche de modélisation satistique est utilisée pour modéliser la variabilité observée et identifier les sources de variations, en termes de sensibilité à chaque source de variabilité, en utilisant un modèle physique compact comme Leti-UTSOI. Le modèle compact est d’abord étalonné sur les courbes C-V et I-V dans différentes conditions de polarisation et géométries. L’analyse des FOM et de leurs corrélations a permis d’identifier les dépendances manquantes dans le modèle compact. Celles-ci ont également été incluses en apportant de petites modifications au modèle compact. / The ``Moore's Law'' has defined the advancement of the semi-conductor industry for almost half a century. The device dimensions have reduced with each new technology node, and the design community and the market for the semiconductor have always followed this advancement of the industry and created applications which took better advantage of these new devices. But during the past decade, with the device dimensions approaching the fundamental limits imposed by the materials, the pace of this scaling down of device dimensions has decreased. While the technology struggled to keep alive the spirit of ``Moore's Law'' using innovative techniques like 3-D integration and new device architectures, the market also evolved to start making specific demands on the devices, like low power, low leakage devices demanded by Internet of Things (IoT) applications and high performance devices demanded by 5-G and data centre applications. So the semiconductor industry has slowly moved away from being driven by technology advancement, and rather it is now being driven by applications.Increasing power dissipation is an unavoidable outcome of the scaling process, while also targeting higher frequency applications. Historically, this issue has been handled by replacing the basic transistors (BJTs by MOSFETs), freezing the operation frequency in the system, lowering supply voltage, etc. The reduction of supply voltage is even more important for low power applications like in IoT, but this is limited by the device variability. Lowering the supply voltage implies reduced margin for the designers to handle the device variability. This calls for access to improved tools for the designers to predict the variability in the devices and evaluate its effect on the performance of their design and innovations in technology to reduce the variability in the devices. This thesis concentrates in the first part, and evaluates how the device variability can be accurately modelled and how its prediction can be included in the compact models used by the designers in their SPICE simulations.At first the thesis analyses the device variability in advanced FD-SOI transistors using direct measurements. In the spatial scale, depending on the distance between the two devices being considered, the variability can be classified into intra-die, inter-die, inter-wafer, inter-lot or even between different fabs. For the sake of simplicity all the variability within a single die can be grouped together as local variability, while others as global variability. Finally between two arbitrary device, there will be contributions from both local and global variability, in which case it is easier to term it as the total variability. Dedicated measurement strategies are developed using specialized test structures to directly evaluate the variability in different spatial scales using C-V and I-V characterisations. The effect of variability is first analysed on selected figure of merits (FOMs) and process parameters extracted from the C-V and I-V curves, for which parameter extraction methodologies are developed or existing methods are improved. This analysis helps identify the distribution of the parameters and the possible correlations present between the parameters.A very detailed analysis of the device variability in advanced FD-SOI transistors is undertaken in this thesis and a novel and unique characterisation and modelling methodology for the different types of variability is presented in great detail. The dominant sources of variability in the device behaviour, in terms of C-V and I-V and also in terms of parasitics (like gate leakage current) are identified and quantified. This work paves the way to a greater understanding of the device variability in FD-SOI transistors and can be easily adopted to improve the predictability of the commercial SPICE compact models for device variability.
316

Příprava mezoporézních vrstev oxidu titaničitého materiálovým tiskem / Fabrication of titania mesoporous layers by material printing

Schovancová, Petra January 2011 (has links)
This diploma thesis was focused on the preparation of mesoporous titanium dioxide layers. Mesoporous layers were prepared from titanium tetraisopropoxide as a precursor with addition diethanolamine and polyethylene glycol. These layers were deposited by material printing. This work was also focused on the characterisation of prepared layers. Hydrophilicity of titanium dioxide layers were studied. The photocatalytic activity of the printed titanium layers was tested by the photocatalytic degradation of stearic acid. Bang-gap studies were performed. Quality of prepared layers was inspected by optical microscopy, scanning electron microscopy and atomic force microscopy.
317

Search for antiplasmodial compounds from Ghanaian medicinal plants / Recherche des composés antiplasmodiaux de plantes médicinales Ghanéennes

Komlaga, Gustav 15 December 2015 (has links)
Une enquête ethnobotanique a été menée en Bosomtwi et Sekyere Est Districts de la Région Ashanti, au Ghana, en utilisant des questionnaires validés pour identifier les plantes traditionnellement utilisées pour gérer le paludisme. Cinq plantes avec une utilisation élevée ont été sélectionnés et une extraction préliminaire des matières végétales sélectionnées effectuées avec de l'eau, le methanol, l'acétate d'éthyle et d'éther de pétrole. Les extraits ont été dosés pour l'activité antiplasmodiale utilisant les méthodes antiplasmodiales in vitro. Les deux les plus prometteuses plantes, Phyllanthus fraternus (Phyllanthaceae) et Bambusa vulgaris (Pocea) ont été choisis pour l'isolement bio-guidée de constituants bioactifs en utilisant des méthodes chromatographiques (par exemple TLC, flash chromatographie, HPLC semi-préparative). Élucidation de la structure des composés isolés ont été effectuées en utilisant des méthodes spectroscopiques (par exemple 1D et 2D Magnétique Nucléaires Résonance (MNR), infrarouge et spectrométrie de masse et leur activité antiplasmodiale étudiés. / An ethnobotanical survey was conducted in Bosomtwi and Sekyere East Districts of the Ashanti Region, Ghana, using validated questionnaires to identify plants used traditionally to manage malaria. Five plants with high usage were selected and a preliminary extraction of the selected plant materials done using water, methanol, ethyl acetate and petroleum ether. The extracts were assayed for antiplasmodial activity using in vitro antiplasmodial methods. The two most promising plants, Phyllanthus fraternus (Phyllanthaceae) and Bambusa vulgaris (Pocea) were selected for bio-guided isolation of bioactive constituents using chromatographic methods (e.g. TLC, flash chromatography, semi-preparative HPLC). Structural elucidation of the isolated compounds were done using spectroscopic methods (e.g. 1D and 2D Nuclear Magnetic Resonance, Infrared and mass spectrometry) and their antiplasmodial activity studied.
318

Erarbeitung einer Handlungsanweisung zur Charakterisierung von Verschmutzungen im industriellen Umfeld

Kricke, Sebastian 28 February 2020 (has links)
Um die Sicherheit von Lebensmitteln zu garantieren und die Gesundheit des Verbrauchers zu schützen existieren strenge Vorschriften bezüglich der Hygiene an die Lebensmittelindustrie. Daher handelt es sich bei der Reinigung um einen kritischen Prozessschritt in der Lebensmittelindustrie. Die bei der Reinigung ablaufenden Wirkmechanismen zwischen Reinigungsflüssigkeit und Verschmutzung sind noch nicht vollständig verstanden. Innerhalb der Arbeit wird der Quellungsprozess spezieller Modellverschmutzungen charakterisiert und mithilfe eines entwickelten Versuchsstandes dessen Auswirkung auf die wirkenden Bindungskräfte bestimmt. Zudem wird eine Anleitung erstellt welche der Industrie einfache Methoden für eine solche Verschmutzungscharakterisierung aufzeigt.:Verzeichnis der verwendeten Formelzeichen Verzeichnis der verwendeten Abkürzungen 1 Einleitung 2 Stand der Technik 2.1 Grundlagen der Reinigung 2.2 Einfluss der Bindungskräfte 2.3 Versuchsaufbau zur Bestimmung der Bindungskräfte 2.3.1 Versuchsprinzip nach LIU et al. 2.3.2 Provisorischer Bindungskraftversuchsaufbau 2.3.3 Bindungskraftversuchsaufbau 2.3.4 Differentiation der wirkenden Kräfte bei Verschmutzungsabzug 3 Zielsetzung und Lösungsweg 4 Modellverschmutzungen 4.1 Vaselineverschmutzung 4.1.1 Allgemeines 4.1.2 Chemischer Aufbau und physikalische Eigenschaften der Vaseline 4.1.3 Reproduzierbare Herstellung der Vaselineverschmutzung 4.2 Stärkeverschmutzung 4.2.1 Allgemeines 4.2.2 Chemischer Aufbau und physikalische Eigenschaften der Stärke 4.2.3 Reproduzierbare Herstellung der Stärkeverschmutzung 5 Quellverhalten der Modellverschmutzungen 5.1 Zielsetzung und Vorbetrachtung 5.2 Validierung der Umgebungseinflüsse mittels Vaseline 5.3 Gravimetrische Betrachtung der Stärkequellung 5.3.1 Versuchsdurchführung 5.3.2 Messergebnisse 5.3.3 Erstellung eines Prozessmodells 5.4 Optische Vermessung der Phasengrenze der Stärke 5.4.1 Versuchsdurchführung 5.4.2 Messergebnisse 5.4.3 Erstellung eines Prozessmodells 6 Einflüsse verschiedener Parameter auf Bindungskräfte 6.1 Versuchsplanung 6.2 Vaselineverschmutzung 6.2.1 Auswertung des Versuchsplans 6.2.2 Einfluss des Flächenverschmutzungsgewichts 6.2.3 Einfluss des Rakelspalts 6.2.4 Einfluss der Rakelgeschwindigkeit 6.2.5 Einfluss der Temperatur 6.2.6 Einfluss des Reinigungsmediums 6.3 Stärkeverschmutzung 6.3.1 Auswertung des Versuchsplans 6.3.2 Einfluss des Flächenverschmutzungsgewichts 6.3.3 Einfluss der Quelldauer 6.3.4 Einfluss des Rakelspalts 6.3.5 Einfluss der Rakelgeschwindigkeit 6.3.6 Einfluss des rheologischen Verhaltens 6.3.7 Einfluss des Quellmediums 7 Kombination der Erkenntnisse aus Bindungskraftversuchen und Quellverhalten 7.1 Differentiation der wirkenden Kräfte bei Abzug der Modellverschmutzungen 7.1.1 Vorbetrachtung 7.1.2 Vaselineverschmutzung 7.1.3 Stärkeverschmutzung 7.2 Einfluss der Konzentration der Stärkeverschmutzung 8 Industrienahe Verschmutzungscharakterisierung 8.1 Vereinfachter Versuchsaufbau 8.1.1 Konstruktive Umsetzung 8.1.2 Bestimmung der Versagensart weiterer Verschmutzungen 8.2 Anleitung zur Verschmutzungscharakterisierung 9 Zusammenfassung 10 Ausblick Literaturverzeichnis Abbildungsverzeichnis Tabellenverzeichnis Anlagenverzeichnis
319

Formulace a testování nanočástic z větvených polyesterů s rifampicinem / Formulation and testing of rifampicin-loaded branched polyesters nanoparticles

Balciarová, Andrea January 2018 (has links)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Consultant: doc. RNDr. Milan Dittrich, CSc. Student: Andrea Balciarová Title of Thesis: Formulation and testing of rifampicin-loaded branched polyesters nanoparticles In presented thesis, the main attention in theoretical part is focused on nanoparticles for targeted drug delivery, their types, structure and carriers used for their preparation. Moreover, in this part there is an overview of physicochemical characteristics and preparation methods of polymeric nanoparticles applicable in formulation of pharmaceutical products. The experimental part is concerned on studying the influence of the concentration of biodegradable polymers, the presence of cationic surfactants and rifampicin as model drug substance on nanoparticles΄ size and zeta-potential. The main attention is given to nanoparticles decoration with anionic biopolymers, hyaluronic acid and xanthan gum. The simple method of preparation which is usable in nanosystems formulation that influence biological functions purposefully was tried and tested in different contexts.
320

Biodegradation and ageing of bio-based thermosetting resins from lactic acid

Gomes Hastenreiter, Lara Lopes January 2019 (has links)
The need for replacing petroleum-based polymers has been increasing and bio-based polymers prove to be a suitable solution. The aim of this thesis was to synthesize bio-based resins with different chemical architectures to evaluate the effect of the structure on the properties and on their response to ageing and biodegradation. For this, three different bio-based thermoset resins have been synthesised by reacting one of three distinct core-molecules with lactic acid. The options of core-molecules chosen for this work were ethylene glycol, glycerol and pentaerythritol. Lactic acid was first reacted with a core-molecule by direct condensation, the resulting branched molecule was then end-functionalized with methacrylic anhydride. The amount of moles of lactic acid varied according to which core-molecule it was reacted with, but the chain length (n) was always maintained as three. Part of the samples were characterised by Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile test. DSC and TGA were used for determining the thermal behaviour. FT-IR was used to verify the first and second stage of the reaction and to ascertain the occurrence of the crosslinking reaction. Tensile test was done for investigation of mechanical properties. The ageing and biodegradation tests are useful to ascertain the material possible applications. Therefore, the samples that went through the process of ageing or biodegradation were also characterised in the end of the procedures to further check the effect of those processes on the specimens. The test results indicated that the PENTA/LA cured resin was the most stable thermally. The cured resin’s mechanical properties were similar to each other, so there was no comparison to make in this area. The samples proved to be affected by the biodegradation and the ageing processes, both in visual and structural aspects.

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