Submitted by Oscar Simoes (oscar.simoes@citi.com) on 2011-09-06T20:01:02Z No. of bitstreams: 1 Dissertação Oscar Simoes FINAL.pdf: 585897 bytes, checksum: 7cd8393ba1823e9dcfc4bde821b40736 (MD5) / Approved for entry into archive by Gisele Isaura Hannickel (gisele.hannickel@fgv.br) on 2011-09-08T12:46:40Z (GMT) No. of bitstreams: 1 Dissertação Oscar Simoes FINAL.pdf: 585897 bytes, checksum: 7cd8393ba1823e9dcfc4bde821b40736 (MD5) / Approved for entry into archive by Gisele Isaura Hannickel (gisele.hannickel@fgv.br) on 2011-09-08T12:48:10Z (GMT) No. of bitstreams: 1 Dissertação Oscar Simoes FINAL.pdf: 585897 bytes, checksum: 7cd8393ba1823e9dcfc4bde821b40736 (MD5) / Made available in DSpace on 2011-09-08T12:48:49Z (GMT). No. of bitstreams: 1 Dissertação Oscar Simoes FINAL.pdf: 585897 bytes, checksum: 7cd8393ba1823e9dcfc4bde821b40736 (MD5) Previous issue date: 2011-08-12 / Este trabalho tem três objetivos básicos, tendo como base um banco de dados de taxas reais de câmbio entre Brasil e 21 parceiros comerciais no período de 1957 a 2010. O primeiro objetivo é o de verificar a validade da Paridade do Poder de Compra entre Brasil e seus parceiros comerciais através de três testes de raiz unitária (ADF, PP, KPSS). Para a maioria dos países, os testes de raiz unitária foram inconclusivos ou não rejeitaram raiz unitária quando foram utilizados dados mensais e modelos lineares. Já para dados de periodicidade anual, houve maior aceitação de estacionariedade, além de um número menor de resultados inconclusivos. O segundo objetivo é o de investigar a hipótese em Taylor (2001) de que a meia-vida é superestimada quando a amostra é formada a partir de um processo de agregação temporal pela média. Os resultados confirmam as conclusões de Taylor e superestimam a meia-vida em uma janela de 35% a 56% do que seria a meia-vida calculada a partir de dados de final de período. O terceiro objetivo do trabalho é o de verificar se a taxa real de câmbio possui uma reversão não-linear à média. Considerando dados mensais, foi verificado que na maioria dos testes rejeita-se a hipótese nula de raiz unitária contra a hipótese alternativa de globalmente estacionária, porém não-linear. / This dissertation has three main objectives and is based on real exchange rates between Brazil and 21 commercial counterparties for the period of 1957-2010. The first objective is to verify the validity of the Purchasing Power Parity through 3 different linear unit root tests (ADF, PP, and KPSS). For the majority of the cases, null hypotheses of unit roots could not be rejected or were inconclusive for monthly end-of-period data and linear models. For yearly end-ofperiod data, results were more inclined to accepting stationarity, and the number of inconclusive results was reduced. The second objective is to investigate Taylor’s (2001) conclusion that temporal aggregation overestimates the half-lives of the real exchange rates. Under the tests done, Taylor’s points are confirmed, and half-lives are overestimated by a range of 35% to 56% when aggregated temporally by its means and when compared with endof-period half-lives. The third objective is to verify if real exchange rates have non-linear mean-reversion. Considering monthly data, the majority of the tests confirm non-linearity and global stationarity against the unit root hypothesis

Today’s society requires that transformation of information is done effectively and correctly. In other words, the received message must correspond to the message being sent. There are a lot of decoding methods to locate and correct errors. The main purpose in this degree project is to study one of these methods based on the Euclidean algorithm. Thereafter an example will be illustrated showing how the method is used when decoding a three - error correcting BCH code. To begin with, fundamental concepts about coding theory are introduced. Secondly, linear codes, cyclic codes and BCH codes - in that specific order - are explained before advancing to the decoding process. The results show that correcting one or two errors is relatively simple, but when three or more errors occur it becomes much more complicated. In that case, a specific method is required. / Dagens samhälle kräver att informationsöverföring sker på ett effektivt och korrekt sätt, det vill säga att den information som når mottagaren motsvarar den som skickades från början. Det finns många avkodningsmetoder för att lokalisera och rätta fel. Syftet i denna uppsats är att studera en av dessa, en som baseras på Euklides algoritm och därefter illustrera ett exempel på hur metoden används vid avkodning av en tre - rättande BCH - kod. Först ges en presentation av grunderna inom kodningsteorin. Sedan introduceras linjära koder, cykliska koder och BCH - koder i nämnd ordning, för att till sist presentera avkodningsprocessen. Det visar sig att det är relativt enkelt att rätta ett eller två fel, men när tre eller fler fel uppstår blir det betydligt mer komplicerat. Då krävs någon speciell metod.

We investigate into the limitations of the sum-product algorithm for binary low density parity check (LDPC) codes having isolated short cycles. Independence assumption among messages passed, assumed reasonable in all configurations of graphs, fails the most in graphical structures with short cycles. This research work is a step forward towards understanding the effect of short cycles on error floors of the sum-product algorithm. We propose a modified sum-product algorithm by considering the statistical dependency of the messages passed in a cycle of length 4. We also formulate a modified algorithm in the log domain which eliminates the numerical instability and precision issues associated with the probability domain. Simulation results show a signal to noise ratio (SNR) improvement for the modified sum-product algorithm compared to the original algorithm. This suggests that dependency among messages improves the decisions and successfully mitigates the effects of length-4 cycles in the Tanner graph. The improvement is significant at high SNR region, suggesting a possible cause to the error floor effects on such graphs. Using density evolution techniques, we analysed the modified decoding algorithm. The threshold computed for the modified algorithm is higher than the threshold computed for the sum-product algorithm, validating the observed simulation results. We also prove that the conditional entropy of a codeword given the estimate obtained using the modified algorithm is lower compared to using the original sum-product algorithm.

A dissertação analisa as experiências de anticoncepção de mulheres pobres multíparas, considerando os fatores que condicionam a sua autonomia no campo da anticoncepção. A pesquisa foi de cunho qualitativo, do tipo descritivo-exploratório. A coleta das informações foi desenvolvida através da realização de grupos focais com multíparas que freqüentam uma Unidade Básica de Saúde da região metropolitana de Porto Alegre. As informações foram analisadas através de análise de conteúdo proposta por Minayo. A análise sugere que, para as participantes da pesquisa, o número elevado de filhos se justifica em função da sua autonomia contraceptiva reduzida gerada por fatores sociais e individuais. A análise indicou os seguintes fatores como implicados na produção de multiparidade – (1) sociais: dificuldades financeiras, problemas de acesso aos serviços de saúde e aos métodos anticoncepcionais e desigualdades de poder de gênero e (2) individuais: efeitos colaterais dos métodos anticoncepcionais e a auto-responsabilização pelo controle da fertilidade do casal. A multiparidade traz repercussões negativas para a vida dessas mulheres e, apesar de as participantes da pesquisa, em alguma medida, terem consciência dos fatores que limitam o seu potencial de autonomia para escolherem quando e quantos filhos ter, elas parecem não ter poder para modificar essa situação. No entanto, como o poder circula nas relações, suas falas sugerem que existe sempre a possibilidade de que elas ocupem posições de poder e consigam minimizar as dificuldades que enfrentam para controlar sua fertilidade. A pesquisa permite concluir que a retórica produzida no campo do planejamento familiar e sua ênfase na defesa dos direitos reprodutivos contradizem as experiências vividas pelas mulheres pobres que participaram desta pesquisa, no sentido de que essas mulheres não estão exercendo o direito de controlar sua fertilidade. O estudo traz contribuições para o trabalho dos profissionais de saúde no sentido de indicar não só as circunstâncias e os fatores implicados com a produção do fenômeno da multiparidade em comunidades pobres, como também de mostrar os limites das ações e dos serviços que atuam no campo do planejamento familiar. / This dissertation analyzes experiences of contraception among low-income multiparae women, considering factors that condition their autonomy in the field of contraception. The research is characterized as qualitative, descriptive-exploratory. Data collection was carried out through focus groups of multiparae women who attended a Basic Health Unit in Porto Alegre. Information was analyzed through the content analysis proposed by Minayo. The analysis has suggested that, for the participants of this research, the high number of children is justified by their reduced contraceptive autonomy, which is generated both by social and individual factors. The analysis has pointed out the following factors as being implied in the production of multiparity. (1) Social: financial problems, difficult access to health services and contraceptive methods, and inequality of gender power; (2) Individual: side effects of the contraceptive methods, and self-responsibility for the couple’s fertility control. Multiparity causes negative effects in those women’s lives and, although the participants of this research, to a certain extent, were aware of the factors that limit their autonomy potential to choose when and how many children to have, they seemed not to have power to change this situation. However, as power circulates in the relationships, their speech suggests that there is always the possibility to occupy power positions and be able to minimize difficulties they face to control their fertility. The research allows for the conclusion that the rhetoric produced in the field of family planning and its emphasis on the advocacy of reproduction rights contradicts the experiences that poor women have had, in the sense that those women are not exercising their right to control their fertility. The study has brought contributions to work of health professionals, not only indicating the circumstances and factors implied in the production of the multiparity phenomenon in low-income communities, but also showing the limits of actions and services that are present in the field of family planning. / La disertación analiza las experiencias de anticoncepción de mujeres pobres multíparas, considerando los factores que condicionan su autonomía en el campo de la anticoncepción. La investigación fue de cuño cualitativo, del tipo descriptivoexploratorio. La colecta de las informaciones fue desarrollada a través de la realización de grupos focales con multíparas que frecuentan una Unidad Básica de Salud de la región metropolitana de Porto Alegre. Las informaciones fueron analizadas a través del análisis de contenido propuesto por Minayo. El análisis sugiere que, para las participantes del estudio, el número elevado de hijos se justifica en función de su autonomía contraceptiva reducida generada por factores sociales e individuales. El análisis indicó los siguientes factores involucrados en la producción de multipariedad – (1) sociales: dificultades financieras, problemas de acceso a los servicios de salud y a los métodos anticoncepcionales y desigualdades de poder de género y (2) individuales: efectos colaterales de los métodos anticoncepcionales y la auto-responsabilidad por el control de la fertilidad de la pareja. La multipariedad trae repercusiones negativas para la vida de esas mujeres y, a pesar de que las participantes de la investigación, en cierta medida, tengan conciencia de los factores que limitan su potencial de autonomía para escoger cuándo e cuántos hijos tener, ellas parecen no tener poder para modificar esa situación. Sin embargo, como el poder circula en las relaciones, sus discursos sugieren que siempre existe la posibilidad de que ellas ocupen posiciones de poder y consigan minimizar las dificultades que enfrentan para controlar su fertilidad. El estudio permite concluir que la retórica producida en el campo de la planificación familiar y su énfasis en la defensa de los derechos reproductivos contradicen las experiencias vividas por las mujeres pobres que participaron de esta investigación, en el sentido de que esas mujeres no están ejerciendo el derecho de controlar su fertilidad. Este estudio también trae contribuciones para el trabajo de los profesionales de la salud en relación a la posibilidad de indicar no solo las circunstancias y los factores implicados en la producción del fenómeno de lamultipariedad en comunidades pobres, como también de mostrar los límites de las acciones y de los servicios que actúan en el campo de la planificación familiar.

A dissertação analisa as experiências de anticoncepção de mulheres pobres multíparas, considerando os fatores que condicionam a sua autonomia no campo da anticoncepção. A pesquisa foi de cunho qualitativo, do tipo descritivo-exploratório. A coleta das informações foi desenvolvida através da realização de grupos focais com multíparas que freqüentam uma Unidade Básica de Saúde da região metropolitana de Porto Alegre. As informações foram analisadas através de análise de conteúdo proposta por Minayo. A análise sugere que, para as participantes da pesquisa, o número elevado de filhos se justifica em função da sua autonomia contraceptiva reduzida gerada por fatores sociais e individuais. A análise indicou os seguintes fatores como implicados na produção de multiparidade – (1) sociais: dificuldades financeiras, problemas de acesso aos serviços de saúde e aos métodos anticoncepcionais e desigualdades de poder de gênero e (2) individuais: efeitos colaterais dos métodos anticoncepcionais e a auto-responsabilização pelo controle da fertilidade do casal. A multiparidade traz repercussões negativas para a vida dessas mulheres e, apesar de as participantes da pesquisa, em alguma medida, terem consciência dos fatores que limitam o seu potencial de autonomia para escolherem quando e quantos filhos ter, elas parecem não ter poder para modificar essa situação. No entanto, como o poder circula nas relações, suas falas sugerem que existe sempre a possibilidade de que elas ocupem posições de poder e consigam minimizar as dificuldades que enfrentam para controlar sua fertilidade. A pesquisa permite concluir que a retórica produzida no campo do planejamento familiar e sua ênfase na defesa dos direitos reprodutivos contradizem as experiências vividas pelas mulheres pobres que participaram desta pesquisa, no sentido de que essas mulheres não estão exercendo o direito de controlar sua fertilidade. O estudo traz contribuições para o trabalho dos profissionais de saúde no sentido de indicar não só as circunstâncias e os fatores implicados com a produção do fenômeno da multiparidade em comunidades pobres, como também de mostrar os limites das ações e dos serviços que atuam no campo do planejamento familiar. / This dissertation analyzes experiences of contraception among low-income multiparae women, considering factors that condition their autonomy in the field of contraception. The research is characterized as qualitative, descriptive-exploratory. Data collection was carried out through focus groups of multiparae women who attended a Basic Health Unit in Porto Alegre. Information was analyzed through the content analysis proposed by Minayo. The analysis has suggested that, for the participants of this research, the high number of children is justified by their reduced contraceptive autonomy, which is generated both by social and individual factors. The analysis has pointed out the following factors as being implied in the production of multiparity. (1) Social: financial problems, difficult access to health services and contraceptive methods, and inequality of gender power; (2) Individual: side effects of the contraceptive methods, and self-responsibility for the couple’s fertility control. Multiparity causes negative effects in those women’s lives and, although the participants of this research, to a certain extent, were aware of the factors that limit their autonomy potential to choose when and how many children to have, they seemed not to have power to change this situation. However, as power circulates in the relationships, their speech suggests that there is always the possibility to occupy power positions and be able to minimize difficulties they face to control their fertility. The research allows for the conclusion that the rhetoric produced in the field of family planning and its emphasis on the advocacy of reproduction rights contradicts the experiences that poor women have had, in the sense that those women are not exercising their right to control their fertility. The study has brought contributions to work of health professionals, not only indicating the circumstances and factors implied in the production of the multiparity phenomenon in low-income communities, but also showing the limits of actions and services that are present in the field of family planning. / La disertación analiza las experiencias de anticoncepción de mujeres pobres multíparas, considerando los factores que condicionan su autonomía en el campo de la anticoncepción. La investigación fue de cuño cualitativo, del tipo descriptivoexploratorio. La colecta de las informaciones fue desarrollada a través de la realización de grupos focales con multíparas que frecuentan una Unidad Básica de Salud de la región metropolitana de Porto Alegre. Las informaciones fueron analizadas a través del análisis de contenido propuesto por Minayo. El análisis sugiere que, para las participantes del estudio, el número elevado de hijos se justifica en función de su autonomía contraceptiva reducida generada por factores sociales e individuales. El análisis indicó los siguientes factores involucrados en la producción de multipariedad – (1) sociales: dificultades financieras, problemas de acceso a los servicios de salud y a los métodos anticoncepcionales y desigualdades de poder de género y (2) individuales: efectos colaterales de los métodos anticoncepcionales y la auto-responsabilidad por el control de la fertilidad de la pareja. La multipariedad trae repercusiones negativas para la vida de esas mujeres y, a pesar de que las participantes de la investigación, en cierta medida, tengan conciencia de los factores que limitan su potencial de autonomía para escoger cuándo e cuántos hijos tener, ellas parecen no tener poder para modificar esa situación. Sin embargo, como el poder circula en las relaciones, sus discursos sugieren que siempre existe la posibilidad de que ellas ocupen posiciones de poder y consigan minimizar las dificultades que enfrentan para controlar su fertilidad. El estudio permite concluir que la retórica producida en el campo de la planificación familiar y su énfasis en la defensa de los derechos reproductivos contradicen las experiencias vividas por las mujeres pobres que participaron de esta investigación, en el sentido de que esas mujeres no están ejerciendo el derecho de controlar su fertilidad. Este estudio también trae contribuciones para el trabajo de los profesionales de la salud en relación a la posibilidad de indicar no solo las circunstancias y los factores implicados en la producción del fenómeno de lamultipariedad en comunidades pobres, como también de mostrar los límites de las acciones y de los servicios que actúan en el campo de la planificación familiar.

Made available in DSpace on 2016-03-15T19:32:58Z (GMT). No. of bitstreams: 1 Marisa Gomes da Costa.pdf: 2649705 bytes, checksum: 9dfdf2c39e3c4389540dc1f3a8f8d26f (MD5) Previous issue date: 2016-02-01 / This study aims to identify the determinants of Brazil country risk level, during the period from February 1995 to August 2015, based on the deviations from the covered interest rate parity condition. These deviations represent a measure of the risk assumed by an investor who choose to invest in a Brazilian security in Brazil, rather than do it abroad. Using Autometrics, an algorithm for automatic model selection, developed by Doornik (2009), thirty-nine explanatories variables were selected from previous studies. The Brazil country risk level is susceptible to changes in the balance of payments, import by GDP, the deviation covered interest rate parity of the previous period, the inflation rate, the change in exports, total debt per GDP, and external debt by exports. / Este estudo propõe-se a identificar os fatores determinantes do nível do risco Brasil, durante o período de fevereiro de 1995 a agosto de 2015, calculado pelos desvios da condição da paridade coberta de juros. Estes desvios representam a medida do risco assumido por um investidor ao optar investir em um título brasileiro no Brasil, ao invés de fazê-lo no exterior. Utilizando a técnica de seleção automática de modelos com a aplicação do algoritmo Autometrics, desenvolvido por Doornik (2009), trinta e nove variáveis explicativas foram selecionadas a partir de estudos anteriores. O nível do risco Brasil é altamente suscetível às variações do balanço de pagamento, da importação por PIB, do desvio da condição da paridade coberta do período anterior, à taxa de inflação, à variação das exportações (em $ e em volume), à dívida total por PIB e à dívida externa pela exportação.

This study has looked at how the diversity of representatives’ backgrounds changed after the introduction of the Binominal parity vote in the French local elections. The aim was to contribute to our understanding of the impact of gender quotas in other dimensions than gender. Another aim was to explore the workings of the Binominal parity vote, which has a unique design and obligates candidates to run as pairs, constituting of one man and one woman. The diversity of each local council in 2011 and 2015 was measured with the Herfindahl-Hirschman Index (HHI). By looking at the changes in HHI, the study has shown that the diversity of representatives and candidates has increased in terms of age and profession, but decreased in terms of party representation. The exact workings of the mechanisms behind the changes have not been established, but some preliminary conclusions have been made. The relationship between the gender quota’s effectiveness and the change in diversity is strong, but statistically insignificant. Societal gender differences cannot be the sole driver of the changes, as the diversity increased among both women and men. If the increased district magnitude from one to two contributed to the increase in diversity, it was not through the strategic matching of representatives, as they are shown to be almost randomly matched.

Cette thèse traite du problème d'observation et d'estimation des variables caractéristiques des systèmes dynamiques. Il s’agit d’une problématique fondamentale qui est au cœur de nombreux domaines relavant des sciences de l'ingénieur. Les travaux sont conduits dans un contexte ensembliste. Les techniques développées pour l’estimation de l’état et des variables d’entrées ont pour objectif final le contrôle de cohérence des systèmes non linéaires à temps continu. Une première approche conjugue les relations de parité et les différentiateurs à modes glissants pour l’estimation des entrées d’un système non linéaire. Les domaines des entrées compatibles avec les mesures sont alors reconstruits grâce à l’analyse par intervalles et aux techniques de satisfaction de contraintes. Il est montré que la relaxation des contraintes de stabilité/coopérativité pour la construction d’un observateur intervalle peut se faire grâce à des changements de base déterminés de différentes manières et pouvant être variants ou invariants dans le temps. Des simulations numériques illustrent les techniques proposées. Une application à un système aéronautique est également présentée à l’aide d’un jeu de données réelles. / This thesis deals with the problem of a dynamical system observation and the estimation of its characteristic variables; the latter point constitutes the core element in many engineering science fields. The final aim is to build a general framework for integrity control and fault detection of such systems within a bounded error context. The developments offered herein make use of parity relations, sliding mode differentiators, interval observers and constraint satisfaction problems. Input reconstruction techniques are developed for a general class of nonlinear continuous-time systems. Domains are reconstructed for the input values which are consistent with the measurements using interval analysis and constraint satisfaction techniques. It is shown that time-varying or invariant coordinate changes may relax the applicability conditions (stability/cooperativity) of the interval observer design methods. Sliding mode differentiators were also used to enhance interval observer accuracy. The proposed approaches are illustrated through computer simulations and they have been applied to aircraft servo loop control surface for robust and early detection of abnormal positions.

Motivée par les besoins du domaine spatial en termes de diagnostic embarqué et d’autonomie, cette thèse s’intéresse aux problèmes de diagnostic, de diagnosticabilité et de diagnostic actif des systèmes hybrides. Un formalisme hybride est proposé pour représenter les deux dynamiques, continues et discrètes, du système. En s’appuyant sur ce modèle, une approche de diagnostic passif est proposée en mariant les techniques des systèmes à événements discrets et des systèmes continus. Un cadre formel pour la diagnosticabilité des systèmes hybrides a également été établi proposant des définitions et des critères pour la diagnosticabilité hybride. Suite à un diagnostic passif ambigu, le diagnostic actif est nécessaire afin de désambiguïser l’état du système. Cette thèse propose donc une approche de diagnostic actif, qui partant d’un état de croyance incertain, fait appel aux propriétés de diagnosticabilité du système pour déterminer la configuration où les fautes peuvent être discriminées. Une nouvelle machine à états finis appelée diagnostiqueur actif est introduite permettant de formaliser le diagnostic actif comme un problème de planification conditionnelle. Un algorithme d’exploration de graphes ET-OU est proposé pour calculer les plans de diagnostic actif. Finalement, l’approche de diagnostic a été testée sur le Système de Contrôle d’Attitude (SCA) d’un satellite de Thales Alenia Space. Le module de diagnostic a été intégré dans la boucle fermée de commande. Des scénarios de faute ont été testés donnant des résultats très satisfaisants. / Motivated by the requirements of the space domain in terms of on-board diagnosis and autonomy, this thesis addresses the problems of diagnosis, diagnosability and active diagnosis of hybrid systems. Supported by a hybrid modeling framework, a passive approach for model-based diagnosis mixing discrete-event and continuous techniques is proposed. The same hybrid model is used to define the diagnosability property for hybrid systems and diagnosability criteria are derived. When the diagnosis provided by the passive diagnosis approach is ambiguous, active diagnosis is needed. This work provides a method for performing such active diagnosis. Starting with an ambiguous belief state, the method calls for diagnosability analysis results to determine a new system configuration in which fault candidates can be discriminated. Based on a new finite state machine called the diagnoser, the active diagnosis is formulated as a conditional planning problem and an AND-OR graph exploration algorithm is proposed to determine active diagnosis plans. Finally, the diagnosis approach is tested on the Attitude Control System (ACS) of a satellite simulator provided by Thales Alenia Space. The diagnosis module is successfully tested on several fault scenarios and the obtained results are reported.

Cette thèse a pour cadre les transmissions sur les réseaux CPL-BE et les réseaux de capteurs à faible capacité. L'état de l'art classique sur la protection de l'information dans la transmission par réseaux de capteurs fait référence à l'utilisation de codage distribué où les relais implémentent des opérations de parité (mélange des flux) sur les data issues des capteurs. Cependant, il est difficile, de par la nature variable de la qualité des liens en liaisons sans fil, de contrôler la qualité du codeur équivalent construit et de maintenir ses performances au cours du temps. C'est pourquoi nous nous sommes orientés dans cette thèse vers la recherche de schémas de codage différents qui résistent mieux à la variation de qualité des liaisons à travers le réseau. Notre choix s'est porté sur le codage par sous-espace inspiré des travaux de Gabidulin. Le but est de former un code qui utilise une métrique simple et résistante pour sécuriser les transmissions sur le réseau. Les codes à métrique de rang répondent bien à ce besoin car il n'y a qu'à contrôler le rang de la matrice obtenue en réception pour vérifier l'intégrité de la transmission. Les codes à métrique de rang et leur algorithme de décodage ont été étudiés dans un premier temps. Puis, les performances du code LRPC proposé concaténé avec les codes convolutifs sont testées dans des schémas de transmission des contextes différents. / This thesis considers the context of transmissions on CPL-BE networks and low-capacity sensor networks. The state of the art on information protection intransmission by sensor networks refers to the use of distributed coding, where therelays implement parity operations (mixing of streams) on data transmitted by thesensors. However, due to the varying nature of the quality of the wireless links, it is difficult to control the quality of the equivalent encoder constructed and to maintain its performance over time. Therefore, in this thesis, we have focused on the search for different coding schemes that are better resist the variation in the quality of the links across the network. Our choice was based on the sub-space coding inspired by Gabidulin's work. The goal is to form a code that uses a simple and resistant metric to secure transmission across the network. Rank metric codes respond well to this need because it only has to control the rank of the matrix obtained in reception to verify the integrity of the transmission. The rank metric codes and their decoding algorithm were studied in a first step. Then, the performance of the proposed LRPC code concatenated with the convolutional codes is tested in transmission schemes of different contexts.