M. Ing. / Fault detection tools have gained popularity in recent years due to the increasing need for reliable and predictable equipments. Transformer bushings account for the majority of transformer faults. Hence, to uphold the integrity of the power transmission and dis- tribution system, a tool to detect and identify faults in their developing stage is necessary in transformer bushings. Among the numerous tools for bushings monitoring, dissolved gas analysis (DGA) is the most commonly used. The advances in DGA and data storage capabilities have resulted in large amount of data and ultimately, the data analysis crisis. Consequent to that, computational intelligence methods have advanced to deal with this data analysis problem and help in the decision-making process. Numerous computational intelligence approaches have been proposed for bushing fault detection. Most of these approaches focus on the accuracy of prediction and not much research has been allocated to investigate the interpretability of the decisions derived from these systems. This work proposes a rough set theory (RST) model for bushing fault detection based on DGA data analyzed using the IEEEc57.104 and the IEC 60599 standards. RST is a rule-based technique suitable for analyzing vague, uncertain and imprecise data. RST extracts rules from the data to model the system. These rules are used for prediction and interpreting the decision process. The lesser the number of rules, the easier it is to interpret the model. The performance of the RST is dependent on the discretization technique employed. An equal frequency bin (EFB), Boolean reasoning (BR) and entropy partition (EP) are used to develop an RST model. The model trained using EFB data performs better than the models trained using BR and EP. The accuracy achieved is 96.4%, 96.0% and 91.3% for EFB, BR and EP respectively. This work also pro poses an ant colony optimization (ACO) for discretization. A model created using ACO discretized achieved an accuracy of 96.1%, which is compatible with the three methods above. When considering the overall performance, the ACO is a better discretization tool since it produces an accurate model with the least number of rules. The rough set tool proposed in this work is benchmarked against a multi-layer perceptron (MLP) and radial basis function (RBF) neural networks. Results prove that RST modeling for bushing is equally as capable as the MLP and better than RBF. The RST, MLP and RBF are used in an ensemble of classifiers. The ensemble performs better than the standalone models.

Le phénomène de l'alternance codique a été connu et étudié depuis le début du XXe siècle. L'intérêt psycholinguistique à l'alternance codique orale a été suivi par des perspectives socio-pragmatiques dans la seconde moitié du XXe siècle ; puis vers la fin du siècle, l'attention des chercheurs a été attirée sur l'alternance codique écrite. Même si l'alternance codique a été bien étudié depuis, il y a encore quelques lacunes. Par exemple, l'intersection de l'écriture bilingue et la critique génétique présente une source de données naturalistes bilingues écrites qui restent fortement peu étudiées. Cette thèse tente de combler cette lacune en fournissant une analyse qualitative et quantitative des brouillons d'examen des apprenants de langue seconde. L'approche multimodale englobe la perspective visuelle, pragmatique et linguistique. Les résultats montrent que l'alternance codique représente un outil que les élèves utilisent habilement dans leur écriture personnelle académique. Néanmoins, les objectifs de son utilisation diffèrent non seulement entre les individus mais aussi entre les sociétés / communautés. Cela souligne la valeur sociolinguistique de l'écriture personnelle bilingue. Ce travail démontre également l'alternance codique dans l'écriture personnelle comme un type indépendant de l'alternance codique, qui peut prendre une place égale à côté de l'alternance codique orale, écrite et littéraire et qui mérite d'être étudié en tant que tel. / The phenomenon of code-switching has been known and researched since the beginning of the 20th century. The psycholinguistic interest in spoken code-switching was followed by socio-pragmatic perspectives in the second half of the 20th century; then towards the end of the century, researchers' attention was drawn to code-switching in writing. Even though language alternation has been well studied since, there are still some lacunae. For example, the intersection of bilingual writing and genetic criticism presents a source of naturalistic bilingual written data which remains significantly under-studied. The present thesis attempts to fill this gap by providing a qualitative and quantitative analysis of second-language learners' examination drafts. The multimodal approach encompasses the visual, the pragmatic and the linguistic perspectives. The findings show that code-switching represents a tool which students skillfully use in their academic personal writing. However, the purposes of its use differ not only among individuals but also among societies/communities. This emphasizes the sociolinguistic value of bilingual personal writing. This work also recognizes code-switching in personal writing as an independent type of code-switching, which can be placed in line with the oral, written and literary code-switching and which merits to be studied as such.

The Regional Integration Agreements surround the international economy as an alternative to total liberalization of markets. Latin America was not astonished with the resurgence of the post-cold war regionalism. Regarding the imperfect customs union Mercosur, even when in this kind of agreement the goal is a Common External Tariff (CET) that would stimulate the external competitiveness under the aegis of the XXIV article of the GATT/OMC, discrimination still persists. In this case, Brazil, by removing restrictions to commerce for the members of the Block, reduced the CET tariff to 10 %. As an effect of the change in trade politics due to integration, a redirection in Mercosur trade flow took place. With a glance on the Brazilian economy and the rice market, which behavioral pattern would these alterations have, under the optics of the customs unions approach, knowing that Brazil is a loyal rice importer from Argentina and Uruguay now with the benefit of the absence of tariff restriction? According to the Vinerian approach, these effects might be beneficial trade creation or damaging trade diversion for the economical welfare. These effects to Mercosur can be measured with a partial equilibrium model for the cereal in order to find the potential of trade creation and diversion after the change in Brazil s import politics. As a result, we find that the greatest trade potential was created with the tariff reduction in the Block, from 1995 to 1999, as well as the trade creation surpassed the trade diversion to the Block from 1991 to 1994. Regarding the trade creation, Argentina was the more benefited country to the removal of tariffs. Nevertheless, the trade creation has gradually diminished for both members of the Mercosur. As consequence the Brazilian internal production has been more competitive than the imports, even without tariff protection. Regarding trade diversion, its values were minimal, so the damages to third party trade represent somewhat if compared to the potential of trade creation in the Block. Finally, it was clear that the alterations of the rough rice trade tariff allowed a great potential of trade creation and a real impact on the Brazil importation and internal production of rice. / Os Acordos Regionais de Integração permeiam a economia internacional como uma alternativa à total liberalização dos mercados. No caso a união aduaneira imperfeita do Mercado Comum do Sul (Mercosul) alterou a dinâmica do mercado de arroz. Nesse caso, o Brasil ao remover as restrições ao comércio para os membros do Bloco reduziu a proteção em uma TEC de 10%. Como efeito, a mudança nos instrumentos de política comercial, em função da integração, geraram uma re-orientação dos fluxos de comércio no Mercosul. Com um olhar na economia brasileira e sobre o mercado de arroz, essas alterações, pela ótica da abordagem das uniões aduaneiras, teriam qual padrão de comportamento, sabendo que o Brasil é fiel importador de arroz da Argentina e Uruguai agora beneficiados pela ausência de restrição tarifária? Segundo a abordagem Vineriana esses efeitos poderiam ser benéficos criação de comércio ou prejudiciais desvio de comércio para o bem-estar econômico. Os efeitos, criação e desvio de comércio, ocorridos no Mercosul foram mensurados por meio de um modelo de equilíbrio parcial para o cereal a fim de estimar o potencial de comércio criado e desviado. Como resultado, tem-se que no período de 1995 a 1999 se concentra o maior potencial de comércio criado com a desgravação tarifária no Bloco. Bem como, o comércio criado entre 1991 e 1994 superou o comércio desviado para dentro do Bloco. Sob essa ótica, a partir da direção comércio criado, a Argentina foi país que mais se beneficiou com a remoção das tarifas. Contudo, o comércio criado, paulatinamente, diminuiu ao longo do tempo para ambos os membros do Mercosul. Do lado do desvio de comércio, seus valores foram mínimos e, dessa forma, os prejuízos ao comércio com terceiros, pouco representam se comparado ao potencial de comércio criado no interior do Bloco. Por fim, ficou claro que mediante a alterações na tarifa, no comércio de arroz, existe um grande potencial de criação de comércio e um real impacto sobre as importações e produção brasileira de arroz.

[pt] Baseando -se no contexto das mudanças climáticas, esta pesquisa fundamenta seus estudos na relação entre o fenômeno atmosférico da Frente Polar Atlântica (FPA) e os impactos de eventos extremos, especificamente no litoral carioca, partindo da premissa que, decorrente do aumento destes eventos frontais atmosféricos, estaria ocorrendo um consequente aumento do número de ressacas oceânicas com potenciais repercussões litorâneas negativas. O trabalho tem como objetivo identificar esta tendência dos impactos de eventos costeiros extremos sobre a linha de costa carioca a partir da análise das ocorrências históricas da expansão da Frente Fria Polar Atlântica ao longo das últimas três décadas (1988 – 2017). Para alcançar o objetivo proposto foram realizadas a aquisição de dados secundários meteorológicos, oceânicos e de registros midiáticos, baseados nas seguintes etapas: estudo numérico da frequência absoluta total da FPA (primeira etapa), assim como de ressacas significativas (segunda etapa) e eventos de impactos costeiros (terceira etapa), além da elaboração estatística do coeficiente de correlação e a frequência relativa percentual entre estes eventos (quarta etapa). Diante disto, obteve-se uma correlação positiva moderada, capaz de comprovar a hipótese desta dissertação de que há de fato uma variação numérica simultânea quanto à ocorrência das FPA s e os impactos costeiros sobre a orla carioca. Finalizando, a quinta etapa metodológica se baseou no processamento dos dados sobre a frequência histórica dos impactos costeiros, elaborando o mapa de frequência dos impactos costeiros (FIC S) no município do Rio de Janeiro (1988 – 2017), a partir do software ArcGis 10.3 e Google Earth Pro. / [en] Based on the context of climate change, this research bases its studies on the relationship between the atmospheric phenomenon of the Atlantic Polar Front (FPA) and the impacts of extreme events, specifically on the coast of Rio de Janeiro, based on the premise that, due to the increase in these frontal events atmospheric conditions, there would be a consequent increase in the number of ocean surfs with potential negative coastal repercussions. The work aims to identify this trend of the impacts of extreme coastal events on the coast of Rio de Janeiro from the analysis of the historical occurrences of the expansion of the Cold Atlantic Polar Front over the last three decades (1988 - 2017). To achieve the proposed objective, the acquisition of secondary meteorological, oceanic data and media records was carried out, based on the following steps: numerical study of the total absolute frequency of the FPA (first stage), as well as significant hangovers (second stage) and events of coastal impacts (third stage), in addition to the statistical elaboration of the correlation coefficient and the percentage relative frequency between these events (fourth stage). In view of this, a moderate positive correlation was obtained, capable of proving the hypothesis of this dissertation that there is in fact a simultaneous numerical variation as to the occurrence of FPA s and the coastal impacts on the Rio shore. Finally, the fifth methodological step was based on the processing of data on the historical frequency of coastal impacts, elaborating the frequency map of coastal impacts (FIC S) in the municipality of Rio de Janeiro (1988 - 2017), using the software ArcGis 10.3 and Google Earth Pro.

Master thesis deals with the selection of a suitable information system for company ELKOV elektro a.s., which deals with the sale of electronic material and luminaries. A Suitable system is selected using rough and fine selection according per company's requirements. The thesis also contains timetable for implementation and economic evaluation.

A Matlab numerical model for scattering simulation was proposed based on the solution derived from the Beckmann-Kirchhoff scalar theory of scattering of electromagnetic waves from rough surfaces. A series of various synthetic surface samples were obtained using the open source software Gwyddion on which numerical simulations of scattering were carried out. The validity of this numerical model was tested and compared with experimental results.

The principle of an original instrument for experimental measurement of electromagnetic wave scattering from rough planar surfaces is presented in the diploma theses. A design and realization of the instrument is presented too. The instrument is primarily intended for measurement of angle intensity distribution of light scattered from solar cells surfaces. Owing to a possibility to analyse surfaces with a high level anisotropy of electromagnetic wave scattering it is possible to use the instrument for a study of surfaces with an arbitrary type of the surface roughness.

La présente thèse traite de la théorie des équations stochastiques en dimension finie. Dans la première partie, nous dérivons des conditions géométriques nécessaires et suffisantes sur les coefficients d’une équation différentielle stochastique pour l’existence d’une solution contrainte à rester dans un domaine fermé, sous de faibles conditions de régularité sur les coefficients.Dans la seconde partie, nous abordons des problèmes d’existence et d’unicité d’équations de Volterra stochastiques de type convolutif. Ces équations sont en général non-Markoviennes. Nous établissons leur correspondance avec des équations en dimension infinie ce qui nous permet de les approximer par des équations différentielles stochastiques Markoviennes en dimension finie.Enfin, nous illustrons nos résultats par une application en finance mathématique, à savoir la modélisation de la volatilité rugueuse. En particulier, nous proposons un modèle à volatilité stochastique assurant un bon compromis entre flexibilité et tractabilité. / The present thesis deals with the theory of finite dimensional stochastic equations.In the first part, we derive necessary and sufficient geometric conditions on the coefficients of a stochastic differential equation for the existence of a constrained solution, under weak regularity on the coefficients. In the second part, we tackle existence and uniqueness problems of stochastic Volterra equations of convolution type. These equations are in general non-Markovian. We establish their correspondence with infinite dimensional equations which allows us to approximate them by finite dimensional stochastic differential equations of Markovian type. Finally, we illustrate our findings with an application to mathematical finance, namely rough volatility modeling. We design a stochastic volatility model with an appealing trade-off between flexibility and tractability.

Railway vehicles require a certain level of adhesion between wheel and rail to operate efficiently, reliably, and economically. Different levels of adhesion are needed depending on the vehicle running conditions. In the wheel tread–railhead contact, the dominant problem is low adhesion, as low adhesion on the railhead negatively affects railway operation: on one hand, the vehicle will lose traction resulting in delay when driving on low-adhesion tracks; on the other hand, low adhesion during deceleration will extend the braking distance, which is a safety issue. This thesis examines the influence of several contaminants, i.e., water, oil, and leaves, on the adhesion in the wheel tread–railhead contact. This study will improve our knowledge of the low-adhesion mechanism and of how various contaminants influence adhesion. The thesis consists of a summary overview of the topic and three appended papers (A–C). Papers A and B focus mainly on water and oil contamination examined using two methods, numerical simulation and lab testing. In paper A, real measured wheel and rail surfaces, low- and high-roughness surfaces, along with generated smooth surfaces are used as input to the numerical model for predicting the adhesion coefficient. Water-lubricated, oil-lubricated, and dry contacts are simulated in the model. In the research reported in paper B, scaled testing using a mini traction machine (MTM) was carried out to simulate the wheel–rail contact under lubricated conditions. Two types of disc surfaces of different roughnesses were run at different contact pressures and temperatures. A stylus machine and atomic force microscopy (AFM) were used to measure the surface topography. A study of leaf contamination on the railhead surface, based on field testing, is presented in paper C. Railhead surface samples were cut and the friction coefficient was measured on five occasions over the course of a year. Electron spectroscopy for chemical analysis (ESCA) and glow discharge optical emission spectrometry (GD-OES) were used to detect the chemical composition of the leaf-contamination layer on the railhead surface. The main conclusion of the thesis is that different contaminants reduce the adhesion coefficient in different ways. Oil reduces the adhesion coefficient by carrying the normal force due to its high viscosity. Water can reduce the adhesion coefficient to different degrees depending on the surface topography and water temperature. The mixture of an oxide layer and water contamination may have an essential impact. A leaf-formed blackish layer causes low adhesion by means of a chemical reaction between the leaves and bulk material. The thickness of the friction-reducing oxide layer predicts the friction coefficient and the extent of leaf contamination. / QC 20111123

Cut-To-Length (CTL) logging is the dominating logging method in many parts of the world. CTL logging requires a forwarder for the logs from the felling area to a landing area. Due to the harsh off-road working conditions, a well performed suspension system is necessary for the forwarder. A down-scaled forwarder prototype of the full-scale XT28 prototype was developed last year but without any control system. In this project, the forwarder was conducted to the Skogforsk standard rough ground test and development and implementation of a control system was chosen as a refinement task. Structure refinement was also achieved for the improvement of the dynamic behavior. Within the project, the down-scaled version of standard test track was realized as well. The control system with fuzzy logic control strategy was implemented to control the pitch and roll angle when passing the bumps on the track. The scaling effect was investigated with the Buckingham Pi Theorem and utilized to understand the relation between the dynamic behavior of the down-scaled prototype and the full-scale forwarder. During the test, the pitch and roll angle history were collected with a maximum angle of 8 degrees when the forwarder was moving with a speed of 0.06m/s. The test with the control system was recorded but due to the vibration it was hard to collect data in this circumstance. From the test, it is clear that the control system was able to work but its ability was limited owing to the slow reaction speed of the linear actuator. With the analysis of the real hydraulic actuator, it was implied that a better performance could be achieved if this control system was implemented on the full-scale forwarder. / Kortvirkesmetoden är den dominerade avverkningsmetoden i Sverige och resten av Europa. Metoden baseras på två maskiner, en skördare och en skotare, där skotaren transporterar det kapade virket till en uppsamlingsplats för vidare transport med lastbil. För att minska helkroppsvibrationer vid arbete i hård och ojämn terrängen, är det önskvärt att skotaren kan förses med ett effektivt och hållbart fjädringssystem. En nedskalad skotare, baserad på fullskaleprototypen XT28, utvecklades vid ett examensarbete förra året. Skalmodellen saknade styrsystem. I detta projekt realiserades också en nedskalad prototyp av den standardiserade provbana för hård och ojämn terräng som tagits fram av Skogforsk. Ett aktivt styrsystem, med syftet att förbättra skalmodellens dynamisk prestanda i ojämn terräng, utvecklades också för skalmodellens pendelarmar. Den valda reglerstrategin för rollvinkeln, baserades på fuzzi-logik. Skalningseffekterna undersöktes med Buckingham Pi, och dessa resultat användes för att förstå förhållandet mellan dynamiskt beteende hos skalprototypen och fullskaleprototypen. Under testet, registrerades pitch- och rollvinklarna, med en maximal vinkel på 8 grader. Vid provet framfördes skotaren med hastigheten 0,06 m/s. På grund av vibrationerna var det svårt att samla in analyserbara data för styrsystemet. Från testet, är det klart att styrsystemet kunde arbeta som tänkt, men dess förmåga var begränsad på grund av skalmodellens långsamma elektriska ställdonen. Analys av de verkliga hydrauliska ställdonen i fullskaleprototypen indikerar att styrsystemet skulle fungera betydligt bättre för den verkliga skotaren.