La technique de la microscopie à grille de balayage (SGM) consiste à mesurer la conductance d'un gaz bidimensionnel d'électrons (2DEG) sous l'influence d'une pointe balayant la surface de l'échantillon. Dans ce travail, une approche analytique complétée par des simulations numériques est développée pour étudier la relation entre les mesures SGM et les propriétés électroniques locales dans des systèmes mésoscopiques. La correspondance entre la réponse SGM et la densité locale partielle (PLDOS) est étudiée pour un contact quantique entouré d’un 2DEG en présence ou en absence de désordre, pour une pointe perturbative ou non perturbative. Une correspondance SGM-PLDOS parfaite est trouvée pour des transmissions entières et des pointes locales. La dégradation de la correspondance en dehors de cette situation est étudiée. D’autre part, la liaison entre la réponse SGM et la transformée de Hilbert de la densité locale est discutée. Pour étudier le rôle de la force de la pointe sur la conductance SGM, une formule analytique donnant la conductance totale est obtenue. Dans le cas d'une pointe à taille finie nous proposons une méthode basée sur les fonctions de Green permettant de calculer la conductance en connaissant les propriétés non-perturbées. En plus, nous avons étudié la dépendance des branches de la PLDOS en fonction de l’énergie de Fermi. / The scanning gate microscopy (SGM) technique consists in measuring the conductance of a two dimensional electron gas (2DEG) under the influence of a scanning tip. In this work, an analytical approach complemented by numerical simulations is developed to study the connection between SGM measurements and local electronic properties in mesoscopic devices. The connection between the SGM response and the partial local density of states (PLDOS) is studied for the case of a quantum point contact surrounded by clean or disordered 2DEG for perturbative or non-perturbative, local or extended tips. An SGM-PLDOS correspondence is found for integer transmissions and local tips. The degradation of this correspondence out of these conditions is studied. Moreover, a presumed link between the SGM response and the Hilbert transform of the LDOS is discussed. To study the role of the tip strength, an analytical formula giving the full conductance in the case of local tips is obtained. Furthermore, a Green function method enabling to calculate the quantum conductance in the presence of a finite size tip in terms of the unperturbed properties is proposed. Finally the dependence of the PLDOS branches on the Fermi energy is studied.

Abstract Carbon nanotubes (CNTs) have fascinating mechanical, electrical and thermal properties, all of which significantly depend on structural properties such as nanotube length, number of walls, lattice defect densities, impurities and surface functional groups. A number of different applications of carbon nanotubes have been demonstrated during the past two decades including electrical interconnects, transistors, heating and cooling devices, sensors and various actuators. However, further studies on the structure-dependent properties and innovative handling techniques of these materials are needed in order to explore the limitations of use and to be able fully to exploit the advantageous properties of such one-dimensional sp2 hybridized carbon nanomaterials. In this thesis, random networks of single-wall and multi-walled carbon nanotubes (SWCNTs and MWCNTs, respectively) and aligned films of multi-walled carbon nanotubes are studied in the context of three main application fields: gas sensing, electrical interconnects/electrodes and thermal cooling elements. Analyses of associated material properties and some feasible integration techniques are discussed. Single-wall and multi-walled carbon nanotube films cast from aqueous dispersions are shown to be selective nitric oxide sensing components in Taguchi-type sensor devices, in which films based on SWCNTs outperformed those made of MWCNTs. The thickness dependent electrical conduction mechanism of inkjet-printed SWCNT films is also discussed. Robust aligned MWCNT films are demonstrated as soft electrical contact brushes in DC motors and in other moving electrical contacts. The thermal properties of freestanding aligned MWCNT forests are analyzed and shown to be potential alternatives to copper or aluminium in the thermal management of electrical components. / Tiivistelmä Hiilinanoputkien kiehtovat mekaaniset, sähköiset ja lämmönjohto-ominaisuudet ovat kiinnostaneet tutkijoita suuresti viimeisten kahden vuosikymmenen ajan. Monia erilaisia applikaatioita on demonstroitu tänä aikana: mukaan lukien sähköiset kontaktit, transistori-rakenteet, lämmitys- ja jäähdytyslaitteet, anturirakenteet sekä erilaiset aktuaattori-rakenteet. Tämän väitöskirjan päätavoitteena on tutkia hiilinanoputkien toiminnollisuutta ja käytännöllisyyttä erilaisissa sovelluskohteissa. Tässä työssä käytettävät hiilinanoputkirakenteet ovat joko satunnaisjärjestyksessä olevia nanoputkista koostuvia verkostorakenteita tai yhdensuuntaisia, makroskooppisia hiilinanoputkikalvoja. Nanoputkia tutkitaan kolmessa erityyppisessä sovelluskohteessa: kaasuanturisovelluksessa, sähköisissä kontaktirakenteissa sekä jäähdytyselementteinä. Työssä analysoidaan hiilinanoputkirakenteiden ominaisuuksia eri sovelluskohteissa sekä esitetään joitain käyttökelpoisia tekniikoita hiilinanoputkien integroimiseen olemassa oleviin tekniikoihin. Hiilinanoputkien osoitetaan olevan käyttökelpoisia aktiivisia materiaaleja typpioksidille resistiivisessä kaasuanturirakenteessa. Tulosten perusteella yksiseinämäiset hiilinanoputket ovat moniseinämäisiä herkempiä ja parempia kyseisessä sovelluksessa. Lisäksi tutkitaan ja analysoidaan mustesuihku-tulostettujen yksiseinämäisten hiilinanoputkifilmien sähköisten ominaisuuksien riippuvuutta filmin paksuudesta. Vantterien yhdensuuntaisten moniseinämäisten hiilinanoputkirakenteiden osoitetaan toimivan erinomaisesti pehmeinä sähköisinä kontaktielementteinä liikkuvissa sähköisissä kontakteissa. Vapaasti seisovien yhdensuuntaisten, moniseinämäisten hiilinanoputkirakenteiden lämmönjohto-ominaisuuksien tutkiminen ja analysointi osoittaa, että kyseisiä rakenteita voidaan käyttää tehokkaina jäähdytyselementteinä ja mahdollisesti korvaavana vaihtoehtona alumiinille ja kuparille sähköisten komponenttien lämmönhallinta sovelluksissa.

An environmentally sustainable production of electrical power is important for preserving the earth’s natural resources. In order to utilize this power as efficiently as possible, it is of great importance to minimize the losses, for example in sliding electrical contacts. A sliding electrical contact is where current is transferred from one rotating to one stationary component and power is lost due to friction and contact resistance. Also in some signal applications, high performance sliding contacts are crucial to ensure stable signal transfer with low noise. Although sliding electrical contacts are primarily designed for good electrical performance, the system will benefit also from optimization of the tribological properties. The aim of this thesis is to increase the fundamental knowledge of the tribological and electrical performance of metal-graphite composite materials for sliding electrical contacts. The influence of mechanical and electrical load was investigated. Different stationary materials, from pure copper to nanocomposite coatings, were tested against copper- and silver-graphites. Two complementary test setups were used, one with reciprocating and one with unidirectional sliding. Surface analysis was essential to gain deepened understanding of the influence of the interaction on the surfaces. Especially my novel imaging of cross-sections has advanced the level on knowledge in this research field. On the stationary material surface, a tribofilm forms with constituents from the metal-graphite and the surrounding atmosphere. Cross-sectioning reveals a material flow that indicates turbulence. Furthermore, the presence of oxides in the tribofilm is not necessarily detrimental for the contact resistance as long as there is also pure metal available. The presence of graphite is vital for low friction and wear. It is shown that the tribological and electrical behaviour of this system is only marginally influenced by the material selection of the stationary contact. Increasing the metal content in the composite, on the other hand, greatly reduces the contact resistance while there is no significant impact on friction and wear. The mechanical load has to be optimized to compromise between low wear (achieved with low load) and low contact resistance (achieved with high load). Pure mechanical tests show a lower friction and higher wear rate in comparison to tests with a five ampere current.

AfrikaansIn die vroeë Transvaalse koerante se korrespondensiekolomme, sowel as in die eerste Afrikaanse Bybel en die spelreëls vanaf 1875, is ‘n verskynsel bemerk waarvoor daar in dié studie rekenskap gegee word, naamlik dat daar n tydstip was waarin daar ‘n tipe Afrikaans (ATA) bestaan het wat van sowel huidige AB-Afrikaans as AB-Nederlands van die begin van die eeu verskil het. Hiérdie Afrikaans bewys dus dat daar iewers in die ontwikkelingsgang van Afrikaans ‘n proses van vernederlandsing moes plaasgevind het, want ABA en ABN vertoon tans groot ooreenkomste, terwyl die vroeë Transvaalse Afrikaans ‘n karakteristieke eiesoortigheid weerspieel. Vernederlandsing impliseer taalverandering en taalverandering geskied op verskeie wyses: deur middel van natuurlike ontwikkeling, taalkontak, taalversteuring, ensovoorts. In hierdie studie word veral gelet op die produktiewe prosesse van taalverandering wat in Afrikaans werksaam was, te wete sosiale verandering en grammatikale verandering/reëluitbreiding. Laasgenoemde begin in die vorm van variante/wisselvorme - heel moontlik as gevolg van botsende lae, naamlik tussen ‘n standaardnorm en nie-standaardnorm. Die variante vertoon ‘n kenmerkende verspreiding wat in die formule Informele taalgebruik gaan formele taalgebruik voorafuitgedruk kan word. In die meertalige situasie aan die Kaap het daar verskeie nie-standaardvorme van die doelwittaal, Nederlands, bestaan. Omdat taalverandering vanuit die nie-standaardlaag (hierdie informele vlak) van ‘n taal plaasvind, het een van die nie-standaardvorme van Nederlands sekere veranderinge as gesproke taal begin vertoon en sodoende is die proses van die verafrikaansing van die nie-Standaardnederlands vol trek. Tydens die Engelse periode in Suid-Afrika moes Nederlands en Afrikaans hul kragte saamsnoer om teen die magtige kultuurtaal, Engels, te bly voortbestaan. Die aanslag is inderdaad afgeweer en hierna het Afrikaans Nederlands geleidelik as hoëfunksietaal begin vervang. Afrikaans is in 1925 as amptelike taal naas Engels erken – ‘n taal wat in daardie stadium nog nie volle wasdom bereik het nie, maar volgens Regeringsordonnansie sy plek as volwaardige taal as Engels moés inneem. Die eie Afrikaanshede wat diensbaar was aan die nuwe omstandighede van die bestaan is behou, maar verder is daar in hierdie wordingstryd na Nederlands teruggegryp ten opsigte van die woordeskat, spreekwoorde, sinsbou, woordorde, spelling en spelreëls, die wetenskaplike en tegnologiese terminologie, selfs in die daarstelling van ‘n eie Afrikaanse Bybel - die proses van vernederlandsing waaroor hierdie studie dit het. English In this study an account is given of a phenomenon which becomes apparent when studying correspondence columns of the earliest Transvaal papers, the first Afrikaans Bible as well as Afrikaans spelling rules (as from 1875), viz. that there is a distinguishable difference between early written Afrikaans as used in the Transvaal, and modern Afrikaans, and even between this early Afrikaans and Dutch. This clearly proves that there was a time when Afrikaans did not resemble presentday Afrikaans. Why the change? Change in a language is a natural phenomenon. If change takes place in a multilinguistic situation, it may result in the development of so-called non-standard varieties of the dominant language. From 1652 onwards there existed a multilinguistic speech community in South Africa in which different non-standard varieties of the dominant language, Dutch, were found. One of these non-standard varieties developed into Afrikaans (the process of change always originates at a stage of non-standard usage) . In this way the process of Afrikaansification ("verafrikaansing") became complete. When English became the dominant language in South Africa, Dutch as the formal "high" language and Afrikaans as the so-called "low" variety had to combine forces in order to survive the onslaught of Anglicising influences. Afrikaans eventually replaced Dutch as the "high" language and even became one of the official languages of South Africa in 1925. This meant that Afrikaans had to hold its own in opposition to English, but it was a question of whether Afrikaans was vigorous enough to do so. As it obviously was not, it had to borrow from the Dutch lexicon, spelling system, word order and syntactic patterns, as well as from Dutch scientific definition and technical terminology. It even took Dutch as a model for the translation of the first Bible in Afrikaans. Thus, the process of the Dutchification of Afrikaans became a reality. This process may be illustrated as follows: Dutch -----> Afrikaansification -----> Back to Dutch (Thus: Dutchification). staan(en) -----> staat ----> staan / Thesis (DLitt)--University of Pretoria, 2008. / Afrikaans / unrestricted

Cette thèse traite de la modélisation du frittage à l’échelle du Volume Élémentaire Représentatif de la pastille de matériau. L’objectif est de développer des outils numériquesde compréhension des phénomènes physiques mis en jeu lors du frittage. Le domaine d’application ciblé est la fabrication du combustible nucléaire. Une approche multi-Échelle a été mise en oeuvre. Dans un premier temps une modélisation à l’échelle d’un empilement, basée sur la méthode des Éléments Discrets, a été adoptée. Différentes études utilisant cette approche ont été proposées dans la littérature ces dernières années. Tous ces travaux utilisent une méthode discrète explicite. Si certains résultats ont pu être validés expérimentalement,une des limites vient de l’utilisation des méthodes explicites dontle pas de temps critique est très petit. Afin d’augmenter le pas de temps, la masse des particules y est augmentée artificiellement de plusieurs ordres de grandeur. Or,il a été démontré que cette pratique conduit, dans certains cas, à une diminution du réarrangement des particules au sein de l’empilement. Dans cette thèse, une méthode Éléments Discrets implicite appelée Dynamique des Contacts a été adaptée au frittage. Elle permet l’utilisation d’un pas de temps très supérieur à celui des méthodes discrètes explicites et ne nécessite pas d’augmenter artificiellement la massedes particules. La comparaison entre la Dynamique des Contacts et la Méthode des Éléments Discrets explicite montre que notre approche conduit à une représentation plus fidèle du réarrangement. Une validation expérimentale par Microtomographie X ainsi qu’une étude paramétrique sur le frittage des poudres bidispersés sont également présentées pour montrer les possibilités de l’approche discrète appliquée au frittage.La seconde partie est consacrée à une modélisation à l’échelle de deux particules parla méthode des Éléments Finis. Ce modèle repose sur une approche mécanique et vise à représenter de façon plus précise le comportement de deux particules en contact. Les diffusions au joint de grains, en surface et en volume peuvent être représentées. Pour le moment, seules les diffusions en surface et au joint de grains ont été étudiées. Si certaines optimisations restent nécessaires pour que le code soit fonctionnel, plusieurs aspects apparaissent déjà déterminants, comme la courbure de la surface à proximité du joint de grains. A l’avenir, le modèle Dynamique des Contacts du frittage pourra être complété etamélioré grâce aux éléments apportés par le modèle mécanique à l’échelle du grain. / This thesis deals with the simulation of the sintering of nuclear fuel on a pellet scale. The goal is to develop numerical tools which can contribute to a better understandingof the physical phenomena involved in the sintering process. Hence, a multi scale approach is proposed. First of all, a Discrete Element model is introduced. It aims at modeling the motion of particles on a Representative Elementary Volume scale using an original Discrete Element Method. The latter is a Non Smooth Method called Contact Dynamics. Recently, there have been numerous papers about the simulation of sintering using Discrete Element Method. As far as we know, all these papers use smooth methods. Different studies show that the results match well experimental data. However, some limits come from the fact that smooth methods use an explicit scheme which needsvery small time steps. In order to obtain an acceptable time step, the mass of particles have to be dramatically increased. The Non Smooth Contact Dynamics uses an implicit scheme, thus time steps can be much larger without scaling up the mass of particles. The comparison between smooth and non smooth approaches shows thatour method leads to a more realistic representation of rearrangement. An experimental validation using synchrotron X-Ray microtomography is then presented, followedby a parametric study on the sintering of bimodal powders that aims at showing the capacity of this model.The second part presents a mechanical model on the sub-Granular scale, using a Finite Element method. This targets a better understanding of the behavior of twograins in contact. The model is currently being developped but the first results already show that some parameters like the shape of the surface of the neck are very sensitive.In the future, the Non smooth Contact Dynamics model of sintering may be improvedusing the results obtained by the sub-Granular scale mechanical model.

El presente estudio analizó diversas investigaciones relevantes sobre los ascensos en la carrera gerencial, para evaluar si este solo se centra en los méritos que puede alcanzar una persona o en otros factores que deben ser desarrollados. Evidentemente, las empresas buscan a los mejores profesionales para liderar equipos de trabajo en puestos gerenciales; por tal motivo, es importante resaltar los medios que necesitan alcanzar los trabajadores para obtener una posición gerencial exitosa. En este sentido, la relevancia se centró en descubrir los otros factores que permiten tener un desarrollo del tema más amplio, ejemplos, estadísticas, actualidad, la comparación de las diferentes posiciones de los autores, etc. Los resultados de este estudio, identificaron que la meritocracia es uno de los principales temas que abordaron diversos autores en la investigación. Sin embargo, según el contexto y las variables que solicitan los reclutadores y las empresas en la actualidad, se refiere a un conjunto de características que debe poseer el candidato al ser promovido, no basta con merecerlo, debe ser un profesional altamente calificado con los estudios y experiencia adquiridas en su etapa laboral. Es preciso extender las investigaciones para identificar otros factores que sean clave para el ascenso gerencial. La globalización, el crecimiento de las economías, el desarrollo de la tecnología está en constante cambio y las organizaciones deben adaptarse y estar en sintonía a dichos cambios, por tal motivo, es necesario el estudio de otras posturas. / The present study analyzed various relevant research on promotions in the managerial career, to assess whether it only focuses on the merits that a person can achieve or on other factors that must be developed. Obviously, companies look for the best professionals to lead work teams in managerial positions; For this reason, it is important to highlight the means that workers need to achieve to obtain a successful managerial position. In this sense, the relevance focused on discovering the other factors that allow to have a broader development of the subject, examples, statistics, news, the comparison of the different positions of the authors, etc. Meritocracy is one of the main topics addressed by various authors in the research. However, according to the context and the variables requested by recruiters and companies today, it refers to a set of characteristics that the candidate must have when promoted, it is not enough to deserve it, they must be a highly qualified professional with studies and experience acquired in his work stage. Research needs to be extended to identify other factors that are key to managerial advancement. Globalization, the growth of economies, the development of technology is constantly changing and organizations must adapt and be in tune with these changes, for this reason, it is necessary to study other positions. / Trabajo de Suficiencia Profesional

The thesis is focused on the calculation of electrodynamic forces that counterwork on moving contacts of compact circuit breaker BL1600 from the company OEZ Letohrad. The thesis is divided into separates chapters that build on themselves. In the introduction the reason why we deal with calculation of dynamic forces and structural arrangement of current carrying path is described. In the following chapter there is a theoretical analysis of electrodynamic forces that conterwork on individual parts of circuit breaker´s element. The third part is devoted to structural arrangement of the circuit breaker BL1600. In this part we can find an example of using the circuit broker Modeion in practice. Two next chaptures deal with adjustment of the model of current carrying path which then serves for the calculation of electrodynamic forces. The rest of the thesis is devoted to my own calculations. These calculations are mainly stationary where we try to find the forces that conterwork on the contacts in a steady current and in a point in time. There are also dynamics calculation when we can watch the forces that counterwork on contacts in a certain time interval. The last chapter is devoted to a stationary calculation of forces that counterwork on the electrical arc which arises while turning the short-circuit current off. The obtained results are evaluated in partial conclusions of this thesis.

La paralysie cérébrale (PC) est la première cause de l’handicap moteur de l’enfant en France (2 naissances pour 1000). Il s’agit d’une pathologie causée par des atteintes non progressives survenues lors du développement du cerveau chez le foetus ou le nourrisson. L’équin de la cheville est la déformation musculo-squelettique la plus fréquente chez les enfants atteints par la PC. Malgré des thérapies médico-chirurgicales multiples, le taux de récidive post-opératoire demeure très élevé(48%). Une des principales raisons des échecs des thérapies est le manque de connaissance de la biomécanique articulaire et musculaire. Les techniques d’imagerie en IRM dynamique permettent aujourd’hui d’explorer l’appareil musculo-squelettique au cours du mouvement dans les 3 dimensions de l’espace avec une grande précision (<1mm). Cependant, ces techniques viennent avec leur propre liste de problèmes tels que la résolution réduite, l’anisotropie et les artefacts de mouvement. Dans cette thèse, nous abordons ces problèmes en combinant l’information spatiale de l’IRM conventionnel avec l’information temporelle fournie par les séquences IRM dynamique. Nous avons réussi à atteindre l’objectif principal de ces travaux de recherche en développant des algorithmes robustes combinant des aspects informatiques et mathématiques (dont le recalage d’images basé sur l’intensité était le facteur clé) qui nous ont permis de reconstruire les mouvements articulaires et donc d’établir une analyse biomécanique de la cheville en plus de la reconstruction spatio-temporelle de la séquence dynamique en utilisant une approche logeuclidienne. Les algorithmes proposés ont été appliqués sur la base de données actuellement disponible (contenant 6 sujets normaux) et devraient être également appliqués sur une base plus large contenant des sujets pathologiques de la même tranche d’âges afin de comparer les deux populations et de caractériser la pathologie. / Cerebral Palsy (CP) is a common birth pathology in children leading to ankle joint deformity, also known as the Spastic Equinus (SE) deformity, which causes abnormal function of the joint. While the management of ankle disorders focuses on restoring the joint functions, the underlying pathomechanics is not clearly understood yet. To better understand the biomechanics of the pediatric ankle joint, it is crucial to establish in vivo normative joint biomechanics before focusing on pathomechanics studies. Dynamic MRI has made it possible to non-invasively capture the ankle joint during a complete motion cycle. However, dynamic MRI comes with its own set of unique challenges such as low resolution, anisotropy, and motion artifacts. This motivates our choice for combining spatial information of conventional static MRI with temporal information of dynamic MRI sequences. The global aim of this research work is to build computational frameworks and to develop robust intensity-based approaches for estimating the joint motion and deformations from 3D+t MRI data, and thus for deriving the joint kinematics and the joint contact mechanics during a single cycle of dorsiplantarflexion. Due to a lack of sufficient Imaging data in the pediatric cohort, the proposed algorithms are applied on dynamic MRI data (portraying both passive and active ankle motions) from 6 healthy children.

This thesis compares four Czech translations of the novel Thérèse Raquin by the French writer Émile Zola. The introduction is focused on the source text and its author. Then the thesis deals with the reception of Thérèse Raquin in the Czech culture and refers also to its entry on the Russian cultural scene. The second part of the thesis is focused on an analysis of the Czech translations. This analysis considers the background in which each text was produced, especially from the point of view of time, and it aims to describe not only the language aspects of each translation, but also the global approach of the translator.

Germanium (Ge) is the most compatible semiconductor material with silicon-based complementary metal-oxide semiconductor technology, which has higher electron and hole mobility than Si, leading to enhanced device performance. In addition, semiconductor nanowires (NWs) have attracted significant attention as promising candidates for next-generation nanoscale devices. Due to their unique geometry and physical properties, NWs show excellent optical and electrical properties such as quantum size effects, enhanced light absorption, and high biological and chemical sensitivity. Furthermore, high response to light irradiation is one of the most significant properties of semiconductor NWs, which makes them excellent candidates for photodetectors. Hence, Ge NWs are promising high-mobility nanostructures for optoelectronic devices. Despite constant improvement in the performance of single NW-based devices, determining their electrical properties remains challenging. Here, a symmetric six-contact Hall bar configuration is developed for top-down fabricated highly doped Ge NWs with different widths down to 30 nm, which simultaneously facilitates Hall effect and four-probe resistance measurements. Furthermore, accurate control of doping and fabrication of metal contacts on n-type doped Ge NWs with low resistance and linear characteristics remain significant challenges in Ge-based devices. Therefore, a combined approach is reported to fabricate Ohmic contacts on n-type doped Ge NWs using ion implantation and rear-side flash lamp annealing. This approach allows the fabrication of axial p–n junctions along the single NWs with different widths. The fabricated devices demonstrated rectifying characteristics in dark conditions. The photoresponse of the axial p–n junction photodetectors was investigated under three different illumination wavelengths of 637 nm, 785 nm, and 1550 nm. Moreover, the fabricated axial p–n junction photodetector demonstrated a high-frequency response up to 1 MHz at zero bias.