A maior parte dos produtos industrializados, principalmente na indústria metal mecânica, sofre algum tipo de processo de usinagem em alguma de suas etapas de produção. A máquina-ferramenta CNC, se destaca atualmente nessa indústria devido sua alta produtividade e precisão. Contudo, erros geométricos em peças usinadas podem prejudicar o desempenho da indústria causando perda de lotes, insatisfação do cliente e mal funcionamento do produto final. Entre as causas de erros geométricos em peças usinadas, erros térmicos da máquina-ferramenta correspondem a 70% do total. Esses podem ser reduzidos com a aplicação de uma estratégia de compensação térmica, a qual pode se basear em um modelo empírico, atuando em conjunto com a correção do sistema de coordenadas em máquinas CNC. Este trabalho obteve modelos de deformação térmica por meio de medições de posição e temperatura durante ciclos de aquecimento e ensaios de usinagem. Visando um modelo robusto com baixo número de sensores, os modelos foram classificados estatisticamente. Além disso seus comportamentos foram analisados segundo modos de erro térmico de cada componente principal da máquina ferramenta. O sistema de compensação foi desenvolvido, implementado e testado utilizando-se um centro de torneamento. / Most manufactured products, mainly in metalworking industry, have some kind of machining process included in their processing stages. The CNC machine tool plays na important role in the industry due to its high productivity and precision. However, geometrical erros in machined parts can decrease the performance of the industry, causing rejected batches, customer dissatisfaction and malfunction of the final product. Among the causes of geometric errors on machined parts, thermal errors of machine tool corresponding to 70% of the total. For CNC machines, these errors can be reduced by implementing a strategy of thermal compensation, wich may be based on an empirical model, working in parallel with the correction of the coordinate system. This research work led to the development of thermal deformation models obtained by measurements of position and temperature cycles for heating and machining tests. Targeting a robust design with a low number of sensors, the statistical models were ranked. In addition, the behavior of the models was analyzed according to the thermal error modes of each main component of the machine tool. The compensation system was developed, implemented and tested in a CNC turning center.

O fenômeno da compensação pode ser identificado em atletas que atuam no mesmo nível de desempenho esportivo, mas, que tenham características morfológicas e funcionais diferentes. Algumas características podem apresentar escores baixos (em relação a seus pares), e são compensadas por outras com escores altos. O objetivo da presente pesquisa foi verificar a existência do fenômeno da compensação em atletas de voleibol infanto-juvenis e adultas por meio de características antropométricas, de aptidão física e psicossociais. As discussões foram realizadas em quatro etapas. Na primeira etapa, foram descritas as características antropométricas, somatotípicas, de aptidão física e psicossociais. Na segunda etapa, foram verificados a idade de início da prática esportiva no vôlei e quantos anos de treinamento cada atleta tinha acumulado em sua carreira. Na terceira etapa, foram averiguadas as semelhanças e as diferenças na combinação dos perfis antropométrico, de aptidão física e psicossocial das atletas, por meio de escores padronizados. Na quarta e última etapa, foi constatada a efetividade da seleção de talentos considerando-se duas variáveis determinantes para o voleibol: a estatura e a impulsão vertical. Os resultados encontrados indicaram que é possível identificar o fenômeno da compensação em atletas de voleibol do mesmo nível de desempenho esportivo. / The compensation phenomenon may be identified in athletes that compete at the same performance level, but achieve this performance level through distinct morphological and functional characteristics. An athlete may present lower scores in some characteristics, but he can compensate them having higher scores in others. The aim of this study was to identify the compensation phenomenon in junior and in senior female volleyball players through anthropometric, motor abilities and psychosocial characteristics. The analysis of the compensation phenomenon was performed in a four-step approach. In the first step, anthropometric, somatotype, motor abilities and psychosocial characteristics were described. In the second step, age of practice start and years each athlete had accumulated in the training career were described. In the third step, similarities and differences of the athletes were analyzed through the combination of anthropometric, motor abilities and psychosocial profile scores padronization. Finally, in the fourth, the efficiency of talent selection was verified considering two determinant characteristics of volleyball players: height and vertical jump. The results showed that is possible to identify the compensation phenomenon in athletes that compete in the same level of sport performance.

Este trabalho tem por objetivo a modelagem numérica das fibras microestruturadas e a proposição de dispositivos inovadores com base nos modelos numéricos construídos. Primeiramente, são implementados dois formalismos distintos: o FDTD (do inglês Finite Diference Time Domain) para a geração dos diagramas de bandas dos cristais fotônicos e o SOR (do inglês Successive Over Relaxation) para a análise modal das fibras. A partir destes modelos, são propostas três aplicações distintas que utilizam as propriedades inovadoras das fibras microestruturadas, a saber: compensador de dispersão a fibra com capacidade de compensar um enlace óptico com cerca de vinte vezes seu comprimento, amplificador Raman com alto ganho óptico e isolador óptico a fibra microestruturada. / The goal of this work is the numerical modeling of microstructured optical fibers and the proposition of novel applications using the model developed. First, two distinct formalisms are implemented, the Finite Difference Time Domain Method (FDTD) to generate the photonic crystal band diagrams and the Successive Over Relaxation method (SOR) to carry out modal analysis on the microstructured optical fibers. By means of these models, three applications are investigated: high performance dispersion compensation fiber, high gain Raman amplifier and microstructured optical fiber isolator.

La présente thèse contribue à la littérature empirique sur la flexicurité en se concentrant sur deux axes de recherche : l’utilisation du chômage partiel par les établissements et le rôle des trois « socles » de la flexicurité - contrat de travail, compétences et territoire (Freyssinet, 2006) - sur la sécurisation des parcours professionnels des individus. En rapport au premier axe, la thèse propose une méthodologie pour évaluer l’efficacité du chômage partiel. Selon deux critères d’efficacité (éviter les licenciements économiques et la disparition des établissements), le chômage partiel ne protège pas l’emploi et il n’est donc pas efficace. Entre 1995 et 2005, il est avant tout un outil de flexibilité. Il ne peut pas s'analyser comme un outil répondant aux principes de la flexicurité. Pour le deuxième axe, nous analysons comment les « socles » de la flexicurité sécurisent les parcours, en s’appuyant sur trois mobilités professionnelles : premier emploi-emploi, emploi-emploi et chômage-emploi. Nous soulignons le rôle central de l’emploi temporaire, des liens entre les entreprises et du lieu de résidence dans le processus de sécurisation des trajectoires. Nous montrons que : (i) les contrats temporaires ne sont pas un obstacle à la stabilisation dans l'emploi, dès lors que leur durée est suffisamment longue ; (ii) les réseaux d’entreprises traduits par l’existence de marchés professionnels ou internes favorisent l’acquisition de compétences facilitant la mobilité entre deux emplois ; (iii) un cadre géographique « défavorisé » dans lequel vit l’individu apparaît comme un obstacle dans la sécurisation de son parcours. / This PhD dissertation provides useful empirical contributions for two research topics about flexicurity: the use of the short-time compensation (STC) program by French establishments and the role of the three “bases” of flexicurity – employment contract, skills and territory (Freyssinet, 2006) – in making professional career paths secure. About the first topic, we develop a methodology to analyse the efficiency of STC and to verify if it could be considered as a flexicurity tool. According to two efficiency criteria (avoiding redundancies and establishment exit), STC does not protect employment and so it is inefficient: Between 1995 and 2005, it represents mainly a flexibility tool. It can not been seen as a tool responding to the principles of flexicurity. In the line of the second topic, we analyse how the “bases” of flexicurity make professional career paths secure, by focusing on three professional mobilities: first employment-employment, employment-employment and unemployment-employment. We show the importance of temporary contracts, firm networks and individual’s place of residence in the process of making professional career paths secure. We show that: (i) fixed-term contracts secure professional trajectories if the link between individuals and firms is long enough; (ii) firm networks support the acquisition of skills, making easier professional mobilities; (iii) a “disadvantaged” place of residence seems to be an obstacle in making professional career paths secure.

Cette étude analyse l'ensemble des limites à l'autonomie procédurale des États membres en matière de recours en indemnité ; la recherche est articulée en deux parties, avec une partie préliminaire, et une partie finale.La partie préliminaire est consacrée à l’analyse de la notion d'autonomie procédurale et du droit à l’indemnisation, et elle se compose de deux chapitres, chacun divisés en deux sections. Le premier chapitre est consacré aux limites générales que le droit de l’UE pose à la compétence étatique en matière de procédure, et il essaye de mettre en évidence les différences et les similitudes entre le droit international et droit de l’Union européenne. Le deuxième chapitre de la partie introductive, au contraire, a pour objet l’analyse du droit à indemnisation, et notamment on montre comment en vue d’assurer la protection effective et efficace de ce droit au niveau national, a progressivement été mis en place un processus de limitation de la souveraineté de l’État dans le domaine de la procédure ; ce chapitre essaye aussi de mettre en évidence les différences et les similitudes entre droit international et droit de l’Union européenne.La première partie, au lieu, est consacrée à la signification du qualificatif « statique » du recours en indemnité, car on prend en analyse les limites sur les règles de procédure qui régissent le régime juridique du droit à indemnisation et les conditions de mise en œuvre; elle se compose de deux titres, chacun divisés en deux chapitre, consacrés à l’analyse des limites substantielles et de procédure que le droit de l’UE pose à la compétence nationale à régler le recours en indemnité. Le premier titre de la première partie de cette recherche, dédiée aux limites substantielles, se compose de deux chapitres. Le première chapitre est consacré à la reconstruction des limites aux règles de procédure que représentent les conditions d’imputabilité de la violation à l’État ; en particulier, on prend en compte le grand nombre de cas qui ont donné lieu à des problèmes de cohérence entre les systèmes nationaux de procédure à cause d’une réglementation différente, et souvent contradictoire avec l’élément subjectif de la violation ; plus spécifiquement, on met en place une analyse de la jurisprudence de la Cour de justice qui a donné lieu à la formation prétorienne de nouveaux dispositifs de procédure concernant la responsabilité non contractuelle de l’État-législateur, de l’État administrateur et de l’État-juge. Le deuxième chapitre du premier titre, quant à lui, est consacré aux limites des règles de procédure qui régissent les conditions de mise en œuvre de la responsabilité non contractuelle, c’est-à dire celles qui définissent l’élément objectif de la violation ; plus spécifiquement, on prend en analyse la jurisprudence qui concerne les conflits entre les normes de procédure nationales et les trois conditions qu’il faut réunir pour obtenir l’indemnisation, à savoir : que la règle du droit de l’Union violée ait pour objet de conférer des droits aux particuliers; que la violation de cette règle soit suffisamment caractérisée et qu’il existe un lien de causalité direct entre cette violation et le préjudice subi par les particuliers.[...] / This work analyses the limits that the principle of State liability for damages suffered by individuals because of breach of EU law poses to the procedural autonomy of the Member States of the EU; at the same time, the work provides a concept of procedural autonomy capable of showing its own constitutive limits. The research is divided into two parts, preceded by an introductory part.The introductory part of this work is dedicated to the general character of the limitations EU law poses to the State’s competence in matters of procedure/procedural matters. Specifically, it analyzes the process by which the Court of justice and national courts consider the incompatibility of national rules of procedure with the european law; in addition, it highlights the specific conjugation of these limits in the matter of compensation of damages.The first part of the research, instead, focuses on the specific limits that european law poses on the rules of procedure relating to the legal regime of the right to compensation and its operating conditions; in particular, this first part explores respectively the “substantive” and “procedural” limits that EU law poses to the State’s autonomy to regulate actions for damages for breaches of EU law. The substantial limits, which are the object of the first chapter of the first part of this work, concern the conditions of eligibility of liability and to the constitutive conditions of the right to compensation; in particular, these are the limits that the european law pose on national rules of procedure governing the subjective and objective elements of the breach of EU law. Firstly, I analyse the judgments of the Court of justice that gave rise to the formation of procedural provisions related to the eligibility of breaches of EU law by the State-legislator, the State-administrator and the State-judge. Secondly, I derive the set of procedural requirements that national courts have to apply for verifying the existence of a breach of EU law, and especially to verify the existence of the three conditions that have to be met for conferring right to reparation: the infringed rule has to be intended to confer rights on individuals; the breach has to be sufficiently serious; a direct causal link between the breach of the obligation resting on the state and the damage sustained by the injured parties has to be present. The procedural limits to the action for damages, to which the second chapter of the first part of this work is dedicated, refer to the concrete organization and characteristics of the judicial action. I explore here the requirements and common rules that have gradually replaced numerous internal procedure provisions. These are related in particular to the identification of the best forum and the powers ofjurisdiction, as well as to the different aspects of the trial and of its organization, with specific reference to areas affected by substantial EU law. This chapter, therefore, reconstructs the rules related to the identification of the competent jurisdiction and to the power that jurisdiction has to enjoy in order to protect and enforce the european law, focusing on the case of a Member State sued in front of a Court of another Member state; in addition I explore the organization strictu sensu of action of damages, I concentrate on class actions, on the classic theme of limitation periods and decadence and, moreover, on rules concerning evidences.[..]

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This DPhil thesis is a collection of three empirical papers that study the role of firms in the UK labour market. Each chapter focuses on firms at different points in their lifecycle. Young firms are an engine of job creation but little is known about the quality of the jobs that they offer. In Chapter 1, I use a matched employer-employee dataset to study how starting wages and lifecycle earnings of employees differ between young and mature firms. I find that young firms pay a small premium to new hires, but subsequent wage growth is better at mature firms, both within continuing job matches and when individuals change jobs. Crucially, highly-paid and stable jobs at young firms have become increasingly rare over time, as young firms themselves have become less likely to survive and attain high productivity levels - both in absolute terms and relative to mature firms over the same period. Policies that aim to stimulate job growth by encouraging the formation of new firms should therefore pay close attention to the types of firms that form. Chapter 2 asks what determines the proportion of a firm's income that workers receive as compensation. I use longitudinal firm data from a period of substantial labour share variation to understand the firm-level determinants of the labor share of income - a question that has typically only been addressed with country- and sector-level data. Estimating a dynamic model using GMM, I find that firms with greater market power and a higher ratio of capital to labour allocate a smaller proportion of their value added to workers. Testing the impact of tangible and intangible capital on low- and high-wage firms leads to conclusions consistent with the hypothesis of capital-skill complementarity. Overall, the results suggest that firm-level drivers play a key role in the evolution of the aggregate labour share, which has declined significantly since the 1970s. Chapter 3 co-authored with Brian Bell, focuses on mature firms and asks how wages at such firms respond to idiosyncratic firm-level cost shocks. We create a unique dataset that links longitudinal data on workers' compensation to the unexpected costs related to firms' legacy defined benefit pension plans. We show that firms are able to share the burden of such costs when a significant share of their workers are current or former members of the plan. We also find that firms that respond to deficits by closing down the pension plans effectively reduce the total compensation of plan members. These results point to significant frictions in the labour market, which we show are a direct result of the pension arrangement that workers have. Yet closing schemes has an implicit cost for firms, since it reduces the frictions that workers face, and increases mobility.

Le fretting est un endommagement induit par le glissement cyclique à très faible amplitude de deux corps en contact. Il se caractérise par un amorçage d’une fissure en surface, qui peut ensuite propager, menant ainsi à la rupture. Le fretting est présent dans de nombreux secteurs industriels où il constitue un critère de résistance à la fatigue plus ou moins sévère. Ce mémoire s’intéresse aux fissures de fretting qui apparaissent dans une liaison entre pale et disque d’une turbomachine. La sollicitation cyclique de contact est dans ce cas le fruit de la combinaison d’un chargement statique à un chargement vibratoire à très haute fréquence (quelques milliers de Hertz). Pouvoir estimer la durée de vie de la liaison sous un tel chargement est indispensable pour la sécurité des vols. La méconnaissance de certains paramètres d’entrée, la non-proportionnalité du chargement ainsi que les fortes concentrations de contraintes mises en jeu, sont autant de verrous techniques à la modélisation. Ce mémoire de thèse propose une méthode numérique permettant le calcul d’une criticité à amorçage de fretting sous sollicitation vibratoire. Le modèle se décompose en une première phase de calcul des contraintes et déformations cycliques par éléments finis, suivie d’une seconde qui consiste à post-traiter les résultats avec le critère de Dang Van. Le modèle est développé grâce au support d’un banc d’essai innovant qui permet de reproduire les chargements subis par un contact d’une liaison pale/disque. Une utilisation intensive du processus de calcul mis au point permet de tirer des conclusions et de mieux comprendre les phénomènes mis en jeu dans ce type d’endommagement. Une confrontation des différentes études numériques réalisées permet de comparer la représentativité des moyens expérimentaux par rapport aux configurations moteurs réelles. / Fretting is a damage induced by small cyclic slip of two bodies in contact. It is characterized by surface crack initiation, which can then propagate, thus leading to failure. Fretting is present in many industrial environments where it is a more or less severe resistance criterion. This work focuses on the fretting cracks that appear in blade/disk roots of turboshaft engines. In this case, the cyclic contact loading is the result of the combination of a static loading and a high frequency vibratory loading (some thousands of Hertz). Being able to estimate the lifetime of the root under such a solicitation is essential for flight safety. The lack of knowledge of certain input parameters, the non-proportionality of the solicitation as well as the high stress gradient involved, make this phenomenon difficult to predict. This work proposes a numerical method allowing the computation of a fretting crack initiation criterion. First, stresses and deformations fields are computed with finite element method. Then, the post-processing of the fields is done woth Dang Van criterion. The model is developed with the support of an innovative test bench which makes it possible to reproduce the loadings sustained by a a blade/disk root. An intensive use of the computation process developed makes it possible to draw conclusions and provides better understanding of the phenomenon involved in this type of damage. The different numerical studies carried out make it possible to compare the representativeness of the experimental means with respect to the actual engine configurations.

"Patient motion is a significant cause of artifacts in SPECT imaging. It is important to be able to detect when a patient undergoing SPECT imaging is stationary, and when significant motion has occurred, in order to selectively apply motion compensation. In our system, optical cameras observe reflective markers on the patient. Subsequent image processing determines the marker positions relative to the SPECT system, calculating patient motion. We use this information to decide how to aggregate detected gamma rays (events) into projection images (frames) for tomographic reconstruction. For the most part, patients are stationary, and all events acquired at a single detector angle are treated as a single frame. When a patient moves, it becomes necessary to split a frame into subframes during each of which the patient is stationary. This thesis presents a method for splitting frames based on hypothesis testing. Two competing hypotheses and probability model are designed. Whether to split frames is based on a Bayesian recursive estimation of the likelihood function. The estimation procedure lends itself to an efficient iterative implementation. We show that the frame splitting algorithm performance is good for a sample SNR. Different motion simulation cases are presented to verify the algorithm performance. This work is expected to improve the accuracy of motion compensation in clinical diagnoses."

Made available in DSpace on 2015-03-05T19:14:41Z (GMT). No. of bitstreams: 0 Previous issue date: 24 / Nenhuma / O objetivo deste estudo foi verificar se as formas de remuneração dos executivos das Companhias Latino-Americanas influenciam o gerenciamento de resultados contábeis. Realizou-se uma análise empírica de 48 empresas, de 4 diferentes países latino-americanos em um período de 5 anos (entre 2002 e 2006), perfazendo um total de 240 observações. Para verificar a ocorrência de gerenciamento de resultados nas companhias latino-americanas, foi adotado o modelo Kang e Sivaramakrishnan (1995). Os testes estatísticos utilizados foram: U Mann-Whitney e Teste Wald. Os resultados do estudo indicaram indícios de maior nível de gerenciamento de resultados nas empresas que fornecem remuneração não fixa aos seus executivos. / The objective of this study was to determine whether the forms of compensation for executives of companies Latin American influence earnings management. There was an empirical analysis of 48 companies, of 4 different Latin American countries in a period of 5 years (between 2002 and 2006), which totaled of 240 observations. To check the occurrence of earnings management in Latin American companies, the model adopted was Kang and Sivaramakrishnan (1995). The statistical tests used to the validity of regressions were: Mann-Whitney U test and Wald. The findings the study showed signs of greater level of earnings management in companies that ofter variable pay to their executives.