[pt] Esta tese de doutorado é composta de dois artigos científicos com contribuições na área de Smart Grid. Além disso, a tese também contribui para o desenvolvimento de soluções computacionais eficientes para problemas de programação linear mista e inteira. Outra importante contribuição é o desenvolvimento de método de decomposição benders com segundo estágio inteiro e não convexo aplicado ao problema de Transmission Switching. O primeiro artigo científico mostra os benefícios com o advento de uma rede inteligente e o aumento da capacidade do operador do sistema de energia elétrica em tomar ações corretivas em face de ocorrências de contingências. O artigo também analisa consequências práticas na capacidade de self-healing da rede pós-contingência. Em nosso contexto, uma rede self-healing é uma rede com total flexibilidade para ajustar a geração e as linhas de transmissão antes e depois da ocorrência de alguma contingência. Resultados numéricos mostram significantes reduções no corte de carga para cada contingência e no total. Foi considerado um único período que representa a demanda de pico do sistema, comparou-se o novo método com os utilizados em publicações anteriores. O segundo artigo contribui também para a aplicação da tecnologia de Smart Grid, em particular a teoria de Transmission Switching. De fato, desenvolvemos uma estratégia de solução para lidar com a complexibilidade NP-Hard criada pelas variáveis de transmission switching e unit commitment do problema de otimização. Foi desenvolvida uma solução algorítmica baseada na teoria dos grafos. Estudou-se a estrutura topológica desses problemas. Além disso, a maior contribuição foi o desenvolvimento de um novo método de decomposição de benders aplicado para o problema de transmission switching com o segundo estágio inteiro e não convexo. Para lidar com este problema de não convexidade, foi desenvolvido um método de convexificação sequencial, implícito a decomposição de benders. / [en] This PhD Thesis is composed by two papers with contributions on operations research applied to smart grid theory. The first paper highlights the economic and security benefits of an enhanced system operation with the advent of a smart grid technology by introducing a novel model, which is a joint energy and reserve scheduling that incorporates the network capability to switch transmission lines as a corrective action to enhance the system capability to circumvent contingency events. The main goal is to reduce operating costs and electric power outages, by adjusting the network connectivity when a contingency occurs. In such a framework, results show that, with a limited number of corrective switches, the system operator is able to circumvent a wider range of contingencies, while resulting in lower operational costs and reserve levels. In our context, a grid that is capable to adjust its generation and also its topology through post-contingency line switching is called a self-healing grid, and its importance in network security and operating costs is demonstrated in this work. The graph structure is explored in the algorithmic solution of the post-contingency transmission switching problem. Numerical results demonstrate a significant reduction in total load shedding and operating cost. It has been also illustrated an expressive improvement in terms of security and operating cost, in comparison to the transmission switching models previously published. The second paper is an application of a modified Benders decomposition to the post-contingency transmission switching problem. The decomposition is an attempt to deal with the NP-hard optimization problem created by the transmission switching and unit commitment variables. The major contribution is the application of a new benders decomposition approach to the problem of transmission switching, in which the first and second stages problems are a mixed-integer program. To deal with this issue, it is used a Branch and Bound (B&B) procedure for the first-stage problem and a sequential convexification procedure for the second-stage problem.

Cette recherche a pour objet un dispositif de télécollaboration asymétrique qui met en relation des apprentis tuteurs de FLE avec des apprenants distants. Notre objectif est d’examiner le parcours de l’apprenant à travers ses activités et ses échanges avec les tuteurs. La communication entre les deux groupes est exclusivement médiatisée par ordinateur à travers une plateforme d’apprentissage en mode asynchrone (forums) et quasi-synchrone (clavardage). La recherche est focalisée sur les apprenants et elle cherche à voir si leurs échanges en ligne avec les tuteurs se révèlent potentiellement acquisitionnels au plan de l’interaction verbale et de la réflexion sur la langue.La recherche s’inscrit dans le domaine des sciences du langage et plus particulièrement de la didactique des langues, dans la lignée des recherches en apprentissage des langues assisté par ordinateur (ALAO, CALL en anglais). Ayant comme objectif de mieux comprendre le vécu et l’activité des apprenants, de manière holistique, nous faisons appel à d’autres champs d’études, à savoir les sciences de l’éducation, les sciences de l’information et de la communication, les technologies éducatives et la psychologie des apprentissages. Ainsi, notre cadre conceptuel est transdisciplinaire.Nos analyses reposent sur deux axes. Le premier a pour but d’examiner la dimension communicationnelle des échanges en ligne à travers les tâches proposées aux apprenants par les tuteurs. Le second vise à étudier les pratiques « méta » des apprenants, issues du feedback correctif que les tuteurs donnent aux apprenants dans le cadre de leurs tâches. Nous avons recueilli plusieurs types de données et pour répondre à nos questions de recherche, nous recourons à leur triangulation. Nous avons adopté une démarche descriptive et notre analyse est qualitative et empirico-inductive. Nous avons aussi fait appel à l’approche systémique qui nous permet d’étudier l’ensemble des éléments de notre système, interreliés de telle manière que tout changement d’un paramètre a un effet sur les autres.Cette étude a deux visées : herméneutique et praxéologique. D’une part, nous cherchons à étudier et à comprendre l’activité d’apprentissage à travers les technologies tout en prenant en compte les relations qui existent entre le contexte et le sens que l’apprenant accorde à l’apprentissage dans ce même contexte. D’autre part, la recherche propose quelques pistes pédagogiques, interactionnelles et ingénieriques fondées sur les échanges observés ; l’objectif est d’améliorer les pratiques d’apprentissage à partir de la télécollaboration asymétrique étudiée grâce à la modélisation de certains paramètres. / This research looks into an asymmetric telecollaborative exchange, where tutor trainees of French as a foreign language communicate with distance learners. Our work examines students’ paths through their learning activities and exchanges with the tutors. Communication between the two groups is exclusively mediated by computer, via a learning platform in asynchronous and quasi-synchronous mode (forums and chats respectively). The research focuses on learners and aims at studying whether online exchanges with tutors prove to be potentially acquisitional in terms of verbal interaction and reflection on language.The research focuses on language sciences and in particular on applied linguistics in line with research on computer assisted language learning (CALL). With a view to better understanding learners’ experience and activity, in a holistic approach, we also refer to other fields of study, such as educational sciences, information and communication sciences, educational technologies and psychology of learning. Thus, our conceptual framework is transdisciplinary.Our analysis consists of two phases. Firstly, we examine the communicative dimension of online exchanges through tasks designed for the learners by the tutors. Secondly, we study learners’ “meta” practices, coming from the tutors’ corrective feedback on their tasks. We collected several types of data and, in order to answer to our research questions, we used data triangulation. We used a descriptive approach and our analysis is qualitative and empirico-inductive. We also used a systemic approach, which allows us to examine all of the elements of our system. These elements are interrelated in such a way that any change of one parameter has an effect on the others.This study has two goals: hermeneutics and praxeological. On the one hand, we intend to study and understand learning activity through technology, while taking into account the relationship between the context and the meaning that the learner gives to learning within this context. On the other hand, our research suggests some pedagogical leads based on the exchanges we studied; our aim is to improve learning practices from asymmetric telecollaboration observed by modelling certain parameters.

This study investigates the effectiveness of context-specific teaching materials delivered through an adapted process genre model of writing, in enhancing academic writing proficiency of tertiary level English foreign language (EFL) students. The study was conducted at a College of Technology in Oman and was motivated by the low EFL writing level of tertiary students at the college. The study employed a quasi-experimental design in which two main groups (experimental and control) were included. The experimental group received EFL writing instruction for one semester via the especially developed teaching materials, while the control group received EFL writing instruction via the prescribed textbook. The findings indicated statistically significant differences between the experimental and control groups in the Mid-Semester examination (MSE) and the Level-Exit examination (LEE). A qualitative analysis of the experimental group’s writing suggests that this group significantly outperformed the control group in writing fluency and accuracy. Therefore, based on the findings of the current study, it can be concluded that context-specific materials delivered through the proposed process genre model of writing are effective in enhancing tertiary level students’ academic writing proficiency in an EFL context. Specifically, the writing intervention had a positive effect on students’ ability to compose a variety of genres in an examination setting, which is an important finding, given that the process-genre approach to writing is normally not associated with writing in an examination setting. / Linguistics and Modern Languages / D. Litt. et Phil. (Linguistics)

Mgr. Jan Siřínek, The Scenic Principle in Psychotherapy Abstract This dissertation explores the effectivity of a targeted application of body/drama- oriented therapy in the act of inducing a corrective emotional experience. The term scenic- symbolic principle is introduced and meant to 1) ascribe symbolic significance to people, objects, or parts intrinsic to the therapy room; 2) enable these as roles for dramatization; and 3) employ the symbolic significance of physical contact and body motion. Therapeutic schools that use the scenic-symbolic principle are summarized. Detailed attention is given to Pesso Boyden System Psychomotor (PBSP) therapy, in which the scenic-symbolic principle serves as the central instrument in achieving a corrective emotional experience. After examining the theoretical concepts and intervention procedures of PBSP, this paper describes an experiment, in which 40 persons were randomly distributed between experimental and control groups (N = 20 for each group). The goal of the experiment was to achieve a change in attitude towards a job, task, or duty that the subjects were facing, in an effort to reduce negative emotions. While intervention in the experimental group was enriched by using the scenic-symbolic principle, both groups demonstrated significant improvement (pe < 0.001; pc...

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Pacientes portadores de deformidades dentofaciais podem relatar dificuldades de mastigação e fala, desordens temporomandibulares, preocupação com a imagem corporal e baixa autoestima. Frequentemente, buscam tratamento orto-cirúrgico pela motivação de obter melhora notável nos aspectos estético, funcional e psicossocial. A evidência atualmente disponível sobre os benefícios na qualidade de vida relacionada à saúde bucal desta modalidade terapêutica ainda não é conclusiva, devido à diversidade de metodologias adotadas entre os estudos existentes, majoritariamente realizados na América do Norte, Europa, Oriente Médio e Ásia. Logo, é essencial utilizar instrumentos específicos para avaliar os efeitos desta modalidade de tratamento também na vida diária dos pacientes brasileiros. O propósito do presente estudo transversal foi determinar o impacto que o tratamento orto-cirúrgico exerce sobre a percepção de qualidade de vida dos pacientes portadores de deformidades dentofaciais, bem como a influência exercida pelo gênero, idade, renda, escolaridade e características da má oclusão, nas quatro etapas inerentes a esta modalidade de tratamento: (1) Inicial; (2) Preparo ortodôntico para a cirurgia; (3) Pós-cirúrgico; e (4) Contenção (pós-tratamento). Duzentos e cinquenta e quatro pacientes foram entrevistados em três importantes centros de atendimento na cidade do Rio de Janeiro. A qualidade de vida foi avaliada pelos questionários OHIP-14 (Oral Health Impact Profile - Short Version) e pelo OQLQ (Orthognathic Quality of Life Questionnaire) em suas versões traduzidas e validadas para o português. A gravidade da má oclusão e autopercepção estética foram avaliadas com base no Índice de Necessidade de Tratamento Ortodôntico (IOTN) e pelo Índice de Estética Dental (DAI). A análise dos dados foi efetuada pelos testes qui-quadrado, Kruskal-Wallis e modelos de regressão binomial negativa múltipla. Os pacientes dos quatro grupos foram semelhantes em relação ao gênero (p = 0,463), escolaridade (p = 0,276) e renda familiar (p = 0,100). Entre os entrevistados houve o predomínio de mulheres, com ensino médio completo e renda familiar entre 2 e 3 salários mínimos, portadores de má oclusão de Classe III de Angle grave. No modelo de regressão binomial negativa ajustado para os fatores gênero, idade, renda familiar e escolaridade, a qualidade de vida aferida pelo OHIP-14 demonstrou que o grupo Inicial sofreu impactos mais negativos do que os grupos Pós-cirúrgico, Preparo e Contenção; o OQLQ indicou que o grupo Inicial sofreu impactos mais negativos do que os grupos Preparo, Pós-cirúrgico e Contenção, nesta sequência. Não foi detectada influência da idade, renda e escolaridade nestes resultados. Foi observado que o gênero feminino sofreu mais impacto negativo na qualidade de vida, principalmente nas dimensões relativas à função e a aspectos sociais. Concluiu-se que os pacientes que finalizaram o tratamento orto-cirúrgico apresentaram como benefícios menores impactos na qualidade de vida específica e relacionada à saúde bucal, melhor autopercepção estética e menor gravidade da má oclusão, em comparação aos pacientes nas etapas pré e pós-cirúrgica e aos pacientes portadores de deformidades dentofaciais em busca de tratamento. / Patients with dentofacial deformities may complain about having trouble chewing and speaking, temporomandibular joint disorders, dissatisfaction with their own appearance and low self-esteem. They frequently seek out orthosurgical treatment motivated by an expectation of a significant aesthetic, functional and psychosocial improvement. Evidence currently available is not yet conclusive about the benefits of orthognathic surgery towards Oral Health-Related Quality of Life (OHRQoL). This is due to a lack of consensus among the various methods used to measure the changes among the existing studies, mainly performed in North America, Europe, Middle East and Asia. Therefore the use of specific tools is important to evaluate the effects of this therapeutic modality on the daily life of Brazilian patients. The aim of this cross-sectional study was to assess the impact of orthosurgical treatment on patients perceptions of their OHRQoL, and the influence of gender, age, socioeconomic status, schooling and occlusal characteristics, at the four stages of this treatment modality: (1) Initial; (2) Pre-surgical orthodontic treatment; (3) Post-surgical; and (4) Retention (post-treatment). Two hundred and fifty-four patients were interviewed at three important local attendance centers in the city of Rio de Janeiro. Quality of life was evaluated by OHIP-14 (Oral Health Impact Profile - Short Version) and OQLQ (Orthognathic Quality of Life Questionnaire) translated and validated into Brazilian Portuguese. The severity of Malocclusion and aesthetic self-perception were assessed by IOTN (Index of Orthodontic Treatment Need) and DAI (Dental Aesthetic Index). Data analysis was performed using Chi-square and Kruskal-Wallis tests and negative binomial regression models. The four groups shared similar make up in terms of gender (p = 0.463), schooling (p = 0.276) and economic status (p = 0.100). Among those interviewed, there was a predominance of women, who had graduated from high school, and with family income of between two and three minimum wages, presenting severe Class III malocclusion. In the negative binomial regression model, adjusted for gender, age, family income and schooling, the OHRQoL evaluated by OHIP-14 demonstrated that the Initial group presented more negative impact than the Postsurgical, Pre-surgical or Retention groups; OQLQ showed that the Initial group suffered more negative impacts than the Pre-surgical, Post-surgical and Retention groups, in this sequence. Any influence of age, family income and schooling was not detected. The female gender showed more negative impact on the OHRQoL, primarily concerning dental function and social aspects. It was concluded that patients who completed orthosurgical treatment presented the benefit of less acute impacts on the OHRQoL, better self-perception of the aesthetic and less severe malocclusion, when compared to patients at pre and post-surgical stages and those individuals not treated for dentofacial deformities.

This independent degree project investigates how formative feedback on written assignments affect Swedish upper secondary school pupils’ writing skills regarding form, what the effects are, and if the effects are the same for pupils in different ability bands. This was done by a time series analysis of tests where a collection of texts from pupils in different ability bands (E, C, and A) in two different classes was collected. All errors in the texts were counted and categorised, as well with the teachers’ highlighted errors on the pupils’ texts. The errors were further calculated into number of errors per 100 words due to different lengths of the texts. The results showed that there was a somewhat positive effect of the teachers’ feedback overall, and that pupils in lower ability bands processed feedback more effectively than pupils in higher ability bands. However, the results also suggested that in order to fully draw conclusions such as these, a statistical study is necessary to strengthen the results due to the low numbers in the results. The pedagogical implications found showed that teachers need to work differently with feedback for high-grade pupils. In order to do so, teacher education programs must emphasise this and address to teachers how to do this.

O presente trabalho analisou numericamente e experimentalmente as características mecânicas de alças ortodônticas com geometria delta, com e sem helicóide superior. Estudos dessa natureza sobre alças delta sem o helicóide superior ainda não se encontram na literatura. O material utilizado na confecção das alças foi uma liga formada por titânio-molibdênio, comum em aplicações ortodônticas. As simulações numéricas foram realizadas através do método dos elementos finitos (MEF) utilizando elementos tridimensionais e análise para grandes deslocamentos, diferentemente das análises encontradas até o momento para este tipo de alça que são exclusivamente bidimensionais. As alças foram simuladas de acordo com uma situação real de uso clínico, com ativação horizontal (direção x). Nas análises experimentais, onde foram obtidas as forças e momentos reativos, utilizou-se uma plataforma com extensômetros montados em ponte completa de Wheatstone, os quais fornecem valores de tensões elétricas de saída correspondentes à deformação aplicada na alça (corpo de prova). Para a leitura das variações de tensões elétricas foi utilizado um sistema de aquisição de dados da National Instruments, o qual, através do programa Labview, fornece valores de tensões elétricas que são convertidos em forças e momentos calibrando-se a plataforma. Cada valor de força e momento reativo foi tabulado desde a ativação nula até seu valor máximo de ativação, isto é, um pouco antes de atingir o escoamento do material da alça. Além de forças e momentos reativos, foram determinadas as relações momento força (M/F). Tais relações, segundo a literatura, definem o tipo de movimentação dentária em um caso clínico. Os resultados obtidos mostraram que as forças reativas no eixo x nas alças sem helicóide são maiores que nas alças com helicóide. Já as forças reativas de intrusão/extrusão dentária atuantes no eixo y apresentaram valores similares para os dois tipos de alças, sendo muito pequenas e por isso desconsideras nesta pesquisa devido à sua pouca influência nos resultados. Obteve-se uma curva da variação de tensões ao longo das alças em função da ativação, e observou-se que alças sem helicóide apresentam tensões mais altas em um mesmo valor de ativação e consequentemente maior tendência a plastificação. A relação M/F predominante neste trabalho foi a relação Mz/Fx a qual estabelece a maioria dos tipos de movimentos dentários encontrados na literatura e a única para o tipo delta até então. Os tipos de movimentos dentários originados com o uso das alças delta com e sem helicóide, de acordo com a relação Mz/Fx, no plano xy são de rotação de raiz, rotação de coroa e de translação. Partindo-se dos valores de My/Fx infere-se que não há movimentação dentária para este tipo de alça. Outro fator não explorado na literatura e presente nesta pesquisa é a variação angular entre as extremidades e seu impacto nos resultados finais de forças, momentos e relação M/F. / This study analyzed numerically and experimentally the mechanical characteristics of orthodontic springs with delta geometry with and without an upper loop. To our knowledge this kind of study of delta springs without an upper loop has not yet been described in the literature. The material used to make the springs was a titanium-molybdenum alloy commonly used in orthodontic applications. Numerical simulations were performed with finite element modeling (FEM) using three-dimensional elements and large-displacement analysis, unlike the analyses found in the literature to date for this type of spring, which are exclusively two-dimensional. The springs were simulated to reflect a real clinical situation with horizontal activation (in the x direction). In the experimental analysis to determine the reactive forces and moments, a platform with strain gauges mounted on a full Wheatstone bridge whose output voltages corresponded to the strain applied to the spring (the test specimen) was used. The voltage variations were read with the aid of a National Instruments data acquisition system, which, when used with the LabVIEW program, provides voltage values which are converted into forces and moments to calibrate the platform. Each value of force and reactive moment was recorded in a table, from zero activation to the maximum value, i.e., just before the yield strength of the material was reached. In addition to the reactive forces and moments, the moment-to-force ratios (M:F) were measured. According to the literature, these ratios define the type of tooth movement in a clinical case. The results show that the reactive forces along the x-axis in the springs without a loop were greater than in the springs with a loop. In contrast, the reactive intrusive/extrusive forces in the y-axis, which were very small and could be neglected in this study because they had little influence on the results, were similar for both types of spring. A curve showing the change in stress along the spring as a function of activation was plotted. This showed that springs without a loop had higher stresses for a given activation value and therefore a greater tendency to deform plastically. The predominant M:F ratio in this study was the Mz/Fx ratio, which is the moment-to-force ratio that produces most types of tooth movements described in the literature and is to date the only moment-to-force ratio described in the literature for the delta spring. The tooth movements in the xy-plane as a result of the Mz/Fx moment-to-force ratio produced by delta springs with and without a loop are root rotation, crown rotation and translation. Based on the values of My/Fx observed, it can be inferred that this type of spring does not produce any tooth movement in the xz-plane. Another factor that is not explored in the literature but that was considered here is the variation in the angle between the extremities of the spring and its impact on the final forces, moments and M:F ratio.

O presente trabalho analisou numericamente e experimentalmente as características mecânicas de alças ortodônticas com geometria delta, com e sem helicóide superior. Estudos dessa natureza sobre alças delta sem o helicóide superior ainda não se encontram na literatura. O material utilizado na confecção das alças foi uma liga formada por titânio-molibdênio, comum em aplicações ortodônticas. As simulações numéricas foram realizadas através do método dos elementos finitos (MEF) utilizando elementos tridimensionais e análise para grandes deslocamentos, diferentemente das análises encontradas até o momento para este tipo de alça que são exclusivamente bidimensionais. As alças foram simuladas de acordo com uma situação real de uso clínico, com ativação horizontal (direção x). Nas análises experimentais, onde foram obtidas as forças e momentos reativos, utilizou-se uma plataforma com extensômetros montados em ponte completa de Wheatstone, os quais fornecem valores de tensões elétricas de saída correspondentes à deformação aplicada na alça (corpo de prova). Para a leitura das variações de tensões elétricas foi utilizado um sistema de aquisição de dados da National Instruments, o qual, através do programa Labview, fornece valores de tensões elétricas que são convertidos em forças e momentos calibrando-se a plataforma. Cada valor de força e momento reativo foi tabulado desde a ativação nula até seu valor máximo de ativação, isto é, um pouco antes de atingir o escoamento do material da alça. Além de forças e momentos reativos, foram determinadas as relações momento força (M/F). Tais relações, segundo a literatura, definem o tipo de movimentação dentária em um caso clínico. Os resultados obtidos mostraram que as forças reativas no eixo x nas alças sem helicóide são maiores que nas alças com helicóide. Já as forças reativas de intrusão/extrusão dentária atuantes no eixo y apresentaram valores similares para os dois tipos de alças, sendo muito pequenas e por isso desconsideras nesta pesquisa devido à sua pouca influência nos resultados. Obteve-se uma curva da variação de tensões ao longo das alças em função da ativação, e observou-se que alças sem helicóide apresentam tensões mais altas em um mesmo valor de ativação e consequentemente maior tendência a plastificação. A relação M/F predominante neste trabalho foi a relação Mz/Fx a qual estabelece a maioria dos tipos de movimentos dentários encontrados na literatura e a única para o tipo delta até então. Os tipos de movimentos dentários originados com o uso das alças delta com e sem helicóide, de acordo com a relação Mz/Fx, no plano xy são de rotação de raiz, rotação de coroa e de translação. Partindo-se dos valores de My/Fx infere-se que não há movimentação dentária para este tipo de alça. Outro fator não explorado na literatura e presente nesta pesquisa é a variação angular entre as extremidades e seu impacto nos resultados finais de forças, momentos e relação M/F. / This study analyzed numerically and experimentally the mechanical characteristics of orthodontic springs with delta geometry with and without an upper loop. To our knowledge this kind of study of delta springs without an upper loop has not yet been described in the literature. The material used to make the springs was a titanium-molybdenum alloy commonly used in orthodontic applications. Numerical simulations were performed with finite element modeling (FEM) using three-dimensional elements and large-displacement analysis, unlike the analyses found in the literature to date for this type of spring, which are exclusively two-dimensional. The springs were simulated to reflect a real clinical situation with horizontal activation (in the x direction). In the experimental analysis to determine the reactive forces and moments, a platform with strain gauges mounted on a full Wheatstone bridge whose output voltages corresponded to the strain applied to the spring (the test specimen) was used. The voltage variations were read with the aid of a National Instruments data acquisition system, which, when used with the LabVIEW program, provides voltage values which are converted into forces and moments to calibrate the platform. Each value of force and reactive moment was recorded in a table, from zero activation to the maximum value, i.e., just before the yield strength of the material was reached. In addition to the reactive forces and moments, the moment-to-force ratios (M:F) were measured. According to the literature, these ratios define the type of tooth movement in a clinical case. The results show that the reactive forces along the x-axis in the springs without a loop were greater than in the springs with a loop. In contrast, the reactive intrusive/extrusive forces in the y-axis, which were very small and could be neglected in this study because they had little influence on the results, were similar for both types of spring. A curve showing the change in stress along the spring as a function of activation was plotted. This showed that springs without a loop had higher stresses for a given activation value and therefore a greater tendency to deform plastically. The predominant M:F ratio in this study was the Mz/Fx ratio, which is the moment-to-force ratio that produces most types of tooth movements described in the literature and is to date the only moment-to-force ratio described in the literature for the delta spring. The tooth movements in the xy-plane as a result of the Mz/Fx moment-to-force ratio produced by delta springs with and without a loop are root rotation, crown rotation and translation. Based on the values of My/Fx observed, it can be inferred that this type of spring does not produce any tooth movement in the xz-plane. Another factor that is not explored in the literature but that was considered here is the variation in the angle between the extremities of the spring and its impact on the final forces, moments and M:F ratio.

Made available in DSpace on 2014-12-17T14:54:58Z (GMT). No. of bitstreams: 1 ArrheniusVCO_TESE.pdf: 1241211 bytes, checksum: 636a162e62ee1658f0ee78ed1516228d (MD5) Previous issue date: 2011-03-03 / Eventually, violations of voltage limits at buses or admissible loadings of transmission lines and/or power transformers may occur by the power system operation. If violations are detected in the supervision process, corrective measures may be carried out in order to eliminate them or to reduce their intensity. Loading restriction is an extreme solution and should only be adopted as the last control action. Previous researches have shown that it is possible to control constraints in electrical systems by changing the network topology, using the technique named Corrective Switching, which requires no additional costs. In previous works, the proposed calculations for verifying the ability of a switching variant in eliminating an overload in a specific branch were based on network reduction or heuristic analysis. The purpose of this work is to develop analytical derivation of linear equations to estimate current changes in a specific branch (due to switching measures) by means of few calculations. For bus-bar coupling, derivations will be based on short-circuit theory and Relief Function methodology. For bus-bar splitting, a Relief Function will be derived based on a technique of equivalent circuit. Although systems of linear equations are used to substantiate deductions, its formal solution for each variant, in real time does not become necessary. A priority list of promising variants is then assigned for final check by an exact load flow calculation and a transient analysis using ATP Alternative Transient Program. At last, results obtained by simulation in networks with different features will be presented / Na opera??o de sistemas el?tricos verificam-se, eventualmente, viola??es de restri??es operativas, como sobrecargas em linhas de transmiss?o e transformadores de pot?ncia de subesta??es ou viola??es de limites de tens?es em barramentos. Caso o monitoramento dessas grandezas indique poss?veis problemas, ? necess?rio adotar medidas corretivas para elimin?los ou atenuar sua intensidade, devendo a restri??o de carga ser utilizada como ?ltimo recurso. Uma medida de controle bastante eficaz ? a t?cnica intitulada Chaveamentos Corretivos, capaz de influenciar o fluxo de pot?ncia de redes malhadas a partir de altera??es em suas topologias, sem, entretanto, produzir qualquer custo operacional adicional. Em trabalhos anteriores, o c?lculo desenvolvido para verificar a capacidade de uma determinada variante de chaveamento em eliminar a sobrecarga em um ramo espec?fico era realizado atrav?s de redu??o de redes ou atrav?s de an?lises heur?sticas. O presente trabalho objetiva a dedu??o anal?tica de equa??es para estimar a altera??o de corrente em um ramo espec?fico, ap?s a realiza??o de chaveamentos em subesta??es, mediante o emprego de poucos c?lculos, decorrentes de aproxima??es lineares. Para o acoplamento de barras de subesta??es, as dedu??es ser?o baseadas na teoria de curto-circuito e na metodologia da Fun??o de Al?vio. J? para a abertura de barras de subesta??es, ser? deduzida uma nova Fun??o de Al?vio, fundamentada na t?cnica de circuito equivalente. Embora sistemas de equa??es lineares sejam utilizados para fundamentar as dedu??es, sua solu??o formal para cada variante, em tempo real n?o ? necess?ria. A partir das estimativas realizadas, elabora-se uma lista de variantes priorit?rias, para teste final atrav?s de um c?lculo exato de fluxo de carga e de uma an?lise de transit?rios atrav?s do software ATP Alternative Transient Program. Por fim, apresentamse resultados obtidos atrav?s de simula??es em redes el?tricas de caracter?sticas distintas