Internet access in rural areas of Latin America is deficient, since the rural population either does not have access to this technology or does it from public places at a very low speed connection. This situation does not happen with the TV which is more popular and accessible than the Internet, mobile telephony, and even radio. This is why is intended to use the characteristics of the TV broadcast services, specifically Digital Terrestrial Television (DTT) to provide Internet connectivity in places where only the TV signal arrives. Thus DTT technologies such as DVB-RCT published in April 2001 by the European Telecommunications Standards Institute (ETSI), which provides a dedicated wireless return channel in the VHF / UHF for concurrent access from many interactive user terminals using TDMA / OFDMA techniques. As well as DVB-T2 which was published in 2008 by the European standardization Forum (DVB) to efficiently transmit advanced television services such as high definition TV (HDTV) or dimensional TV (3D TV) [1] using OFDM will allow to design a new standard for better performance than RCT that takes advantage of the capacities that give robustness to DVB-T2 and which will be called DVB-RCT2 (Digital Video Broadcasting - Return Channel Terrestrial 2nd Generation), which would consist on a broadcast channel (DL) to receive information from the service provider to the end user, using any DTT technology such as ISDB-Tb, DVB-T or DVB-T2 for this purpose; while for reverse communication (UL) it would properly use the DVB-RCT2 architecture proposed in this PhD study. The aforementioned would make it possible for this new standard to be used throughout Latin America. To validate the design standard, it will be evaluated in terms of coverage and capacity with respect to its predecessor DVB-RCT, and then the channel conditions RCT2 will be emulated in a laboratory. Subsequently socio-economic studies of the new standard will be carried out in order to be able to provide internet connectivity services in rural areas. Finally, the possibility of using 4G wireless networks in the 700 MHz UHF band will be analyzed as well as the band of 1700 MHz (AWS). / El acceso a Internet en zonas rurales de América Latina es deficiente, puesto que la población rural o no tiene acceso a esta tecnología o lo hace desde lugares públicos a una muy baja velocidad de conexión. Esta situación no sucede con la TV la cual es más popular y accesible que el Internet, la telefonía móvil, e incluso que la radio. Es por esto que se pretende utilizar las características de los servicios de difusión de TV, específicamente los de Televisión Digital Terrestre (TDT) a fin de proporcionar conectividad a Internet en lugares donde solo llega la señal de TV. Es así que tecnologías de TDT como DVB-RCT publicada en Abril de 2001 por el Instituto de Normas de Telecomunicaciones Europeo (ETSI - European Telecommunications Standards Institute), que provee un canal de retorno inalámbrico dedicado en las bandas de VHF/UHF para el acceso concurrente desde muchos terminales interactivos de usuario usando técnicas TDMA/OFDMA. Así como DVB-T2 que fue publicado en 2008 por el foro de estandarización europeo (DVB) para transmitir eficientemente servicios avanzados de televisión como TV en alta definición (HDTV) o TV tridimensional (3D TV) [1] utilizando modulación OFDM; permitirán diseñar un nuevo estándar de mejores prestaciones que RCT que aproveche las capacidades que dan robustez a DVB-T2 y al cual se lo llamará DVB-RCT2 (Digital Video Broadcasting - Return Channel Terrestrial 2nd Generation), el mismo que constaría de un canal de difusión (canal descendente) para recibir información desde el proveedor del servicio hasta el usuario final, utilizando para esto cualquier tecnología de TDT como ISDB-Tb, DVB-T o DVB-T2; mientras que para la comunicación inversa (canal ascendente) utilizaría propiamente la arquitectura DVB-RCT2 propuesta en este estudio de doctorado. Lo anteriormente mencionado haría factible que este nuevo estándar pueda ser utilizado en toda Latinoamérica. Para validar el diseño del estándar, se lo evaluará en términos de cobertura y capacidad con respecto a su predecesor DVB-RCT, y después se emulará en laboratorio las condiciones del canal RCT2. Posteriormente se realizarán estudios socio-económicos del nuevo estándar a fin de poder proporcionar servicios de conectividad a Internet en zonas rurales. Por último, se analizará la posibilidad de utilizar redes inalámbricas 4G en la banda UHF de 700 MHz, así como en la banda de 1700 MHz (AWS). / L'accés a Internet en zones rurals d'Amèrica Llatina és deficient, ja que la població rural o no té accés a esta tecnologia o ho fa des de llocs públics a una molt baixa velocitat de connexió. Esta situació no succeïx amb la TV la qual és més popular i accessible que l'Internet, la telefonia mòbil, i inclús que la ràdio. És per açò que es pretén utilitzar les característiques dels servicis de difusió de TV, específicament els de Televisió Digital Terrestre (TDT) a fi de proporcionar connectivitat a Internet en llocs on només arriba el senyal de TV. És així que tecnologies de TDT com DVB-RCT publicada a l'Abril de 2001 per l'Institut de Normes de Telecomunicacions Europeu (ETSI - European Telecommunications Estàndards Institute), que proveïx un canal de retorn sense fil dedicat en les bandes de VHF/UHF per a l'accés concurrent des de molts terminals interactius d'usuari usant tècniques TDMA/OFDMA. Així com DVB-T2 que va ser publicat en 2008 pel fòrum d'estandardització europeu (DVB) per a transmetre eficientment servicis avançats de televisió com TV en alta definició (HDTV) o TV tridimensional (3D TV) [1] utilitzant modulació OFDM; permetran dissenyar un nou estàndard de millors prestacions que RCT que aprofite les capacitats que donen robustesa a DVB-T2 i al qual se'l nomenarà DVB-RCT2 (Digital Vídeo Broadcasting - Return Channel Terrestrial 2nd Generation), el mateix que constaria d'un canal de difusió (canal descendent) per a rebre informació des del proveïdor del servici fins a l'usuari final, utilitzant per a açò qualsevol tecnologia de TDT com ISDB-Tb, DVB-T o DVB-T2; mentres que per a la comunicació inversa (canal ascendent) utilitzaria pròpiament l'arquitectura DVB-RCT2 proposta en este estudi de doctorat. L'anteriorment mencionat faria factible que este nou estàndard puga ser utilitzat en tota Llatinoamèrica. Per a validar el disseny de l'estàndard, se l'avaluarà en termes de cobertura i capacitat respecte al seu predecessor DVB-RCT, i després s'emularà en laboratori les condicions del canal RCT2. Posteriorment es realitzaran estudis socioeconòmics del nou estàndard a fi de poder proporcionar servicis de connectivitat a Internet en zones rurals. Finalment, s'analitzarà la possibilitat d'utilitzar xarxes sense fil 4G en la banda UHF de 700 MHz, així com en la banda de 1700 MHz (AWS). / Radicelli García, CD. (2017). Diseño y validación de la segunda generación del estándar de TDT con canal de retorno inalámbrico, para proveer conectividad a Internet en zonas rurales en Latinoamérica [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/80288 / TESIS

No description available.

Submitted by Rafael Santana (rafael.silvasantana@ufpe.br) on 2017-04-26T16:31:53Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO- Igor Nogueira de Oliveira.pdf: 1932477 bytes, checksum: de99161e3dad0c3f6869af876a3e2b5a (MD5) / Made available in DSpace on 2017-04-26T16:31:53Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO- Igor Nogueira de Oliveira.pdf: 1932477 bytes, checksum: de99161e3dad0c3f6869af876a3e2b5a (MD5) Previous issue date: 2016-03-04 / Desde sua padronização, o protocolo Hypertext Transfer Protocol (HTTP) tornou-se o estado da arte em protocolos de transporte da internet, sendo utilizado para transmissão de arquivos hipertexto e hipermídias, como áudio e vídeo de forma cada vez mais interativa. Porém, o HTTP em suas versões 1.0 e 1.1 apresenta pontos que podem ser otimizados, como o fato de atender requisições de forma síncrona, o que normalmente atrasa a renderização de páginas Web podendo vir a afetar a qualidade de experiência dos usuários. Recentemente, o protocolo HTTP foi atualizado para a versão HTTP/2, recebendo diversas modificações, direcionadas principalmente a melhorias no tocante ao uso dos recursos de rede. Dentre estas melhorias, podese citar a adição do recurso push, que permite que o servidor Web responda a uma solicitação com mais de um recurso ao mesmo tempo. Este trabalho apresenta uma análise de desempenho do recurso push no transporte de páginas Web em conexões HTTP/2. Para tanto, foram realizados experimentos em um ambiente simulado, replicando características de rede presentes na internet. Foram adotados o Total Download Time (TDT) e o Page Load Time (PLT) como métricas de análise e a execução do experimento foi realizada através de requisições de páginas web com diferentes quantidades e tamanhos de objetos. Através dos resultados obtidos, foi possível observar que apesar do protocolo HTTP/2 possuir recursos para a melhoria do carregamento de páginas Web o uso inadequado destes recursos pode causar, em determinadas configurações, degradações no carregamento das páginas. / Since its standardization, the Hypertext Transfer Protocol (HTTP) has been considered the state of the art for transmission of hypertext and hypermedia files, such as audio and vídeo in an interactive way. However, 1.0 and 1.1 versions of HTTP present some weaknesses that may be optimized, such as synchronized requests, which typically slow Web pages rendering thus affecting the end user experience. Recently, the protocol was updated to the 2.0 version and received several modifications, focused mainly on improvements in the network usage. Among these improvements one can cite the addition of push, a feature that allows the server to reply to a request with more than one resource simultaneously. This work presents a performance analysis of push feature on the transport of web pages on HTTP/2 connections. Therefore, experiments were conducted on a prototype environment using Total Download Time (TDT) and Page Load Time (PLT) as metrics, and Web page requests with different amounts and sizes of objects. From the results, one can observe that despite presenting features to improve Web page load time, improper use of these HTTP/2 resources may lead, on certain conditions, to the opposite effect.

The electronics newspaper becomes a main source for online news readers. When facing the numerous stories, news readers need some supports in order to review a topic in short time. Due to previous researches in TDT (Topic Detection and Tracking) only considering how to identify events and present the results with news titles and keywords, a summarized text to present event evolution is necessary for general news readers to retrospect events under a news topic. This thesis proposes a topic retrospection process and implements the SToRe system that identifies various events under a new topic and constructs the relationship to compose a summary which gives readers the sketch of event evolution in a topic. It consists of three main functions: event identification, main storyline construction and storyline-based summarization. The constructed main storyline can remove the irrelevant events and present a main theme. The summarization extracts the representative sentences and takes the main theme as the template to compose summary. The summarization not only provides enough information to comprehend the development of a topic, but also can be an index to help readers to find more detailed information. A lab experiment is conducted to evaluate the SToRe system in the question-and-answer (Q&A) setting. From the experimental results, the SToRe system can help news readers more effectively and efficiently to capture the development of a topic.

The Speedy Delivery (SD) waveform does not undergo dispersion in transmission lines. The waveform was first introduced by Dr. Robert Flake in US Patent 6,441,695 B1 issued on August 27, 2002. Use of the SD waveform allows for high precision time domain measurements on transmission lines. High precision time domain reflectometry (TDR) and time domain transmission (TDT) measurements are described. An example measurement is presented. The design of the experimental apparatus is detailed. Voltage bias adjustments are made during measurements to increase the repeatability. Voltage bias adjustments are examined in detail. Efforts to produce short terminated measurements with high precision are included. A technique for performing TDR measurements with highly attenuated signals is presented with results. / text

O grande desafio da Epidemiologia Genética, atualmente, é identificar, em um espaço de variáveis preditoras de alta dimensão e esparso, fatores de risco genéticos para doenças complexas. Um delineamento amostral útil nestes estudos é coletar dados de trios, que são pequenos núcleos familiares (pai e mãe, livres da doença, e filho afetado) e, em cada indivíduo, obter dados do genótipo de marcadores moleculares, sendo a plataforma de marcadores do tipo SNPs (do inglês, Single Nucleotide Polymorphism), com cerca de 1 milhão de variáveis preditoras genéticas, a mais adotada. Neste trabalho é proposto um procedimento em múltiplos estágios para identificar SNPs associados com a doença em dados de trios. A primeira etapa do procedimento é baseada em uma série de análises unilocos (para cada variável preditora), usando um teste de simetria em tabelas de contingência 2 x 2 (conhecido, em Genética, como teste TDT, do inglês, Transmission Disequilibrium Test). Em um segundo estágio da análise, os resultados destes testes são usados para construir uma estatística de somas acumuladas padronizadas (CUSUM) que permite a seleção de conjuntos de SNPs (isto é, conjuntos de variáveis preditoras), possivelmente associados com a doença. Como um terceiro passo da análise, nas regiões selecionadas no passo dois, são realizadas análises de simetria via testes exatos considerando tabelas 2 x 2 e 4 x 4 (pares de SNPs). A formulação do TDT em termos de testes de simetria é uma inovação na área de Genética e facilita a extensão do caso uniloco para o multilocos. A contribuição deste trabalho reside ainda na formulação exata do teste que é útil em situações de amostras pequenas que ocorrem com frequência em dados de trios. Neste caso inferências parciais foram realizadas a partir de decomposições apropriadas da função de verossimilhança. A modelagem do problema em termos do modelo logístico permitiu concluir que não é necessário corrigir a associação para o efeito de covariáveis avaliadas nos pais. O procedimento é implementado usando recursos dos aplicativos PLINK e R. A aplicação é realizada utilizando dados de 71 trios da população brasileira, em que os indivíduos caso (filhos) foram definidos em termos da ocorrência de uma cardiopatia e, em cada um dos 213 indivíduos, estão disponíveis dados genéticos de uma plataforma de SNPs. / Currently, the great challenge of Genetic Epidemiology is to identify, in a high dimensional and sparse space of predictor variables, genetic risk factors for complex diseases. A useful sampling design in these studies is to collect data from trios, which are small nuclear families (father and mother, free from disease, and affected child), and obtain genotypic information from each individual. The molecular markers platform most commonly used for this purpose is of SNPs (Single Nucleotide Polymorphisms), with about 1 million genetic predictor variables. This work proposes a multi-stage procedure to identify SNPs associated with disease using data from trios. The first step of the procedure is based on a series of single locus analysis (for each predictor variable) using a test for symmetry in 2 x 2 contingency tables (known in genetics as TDT (Transmission Disequilibrium Test). In a second stage of the analysis, the results of these tests are used to construct a standard statistic of the cumulative sums (CUSUM), which allows the selection of sets of adjacent SNPs (ie, sets of predictor variables), possibly associated with the disease. As a third step of the analysis, in the regions selected in step two, are performed an extended analysis of symmetry considering 4 x 4 contingency tables. The TDT formulation in terms of symmetry tests is an innovation in the genetics area and facilitates the extension of the single locus analysis to the multiloci case. The contribution of this work lies in the exact formulation of the symmetry test for square contingency tables that is useful in situations of small sample sizes that often occur in data from trios. In this case, partial inferences were performed from appropriate decompositions of the likelihood function. The structural modeling of the problem in terms of logistic model allowed us to conclude that there is no need to adjust the association for data from parents, but only for the effect of covariates evaluated in each parental haplotype. The procedure is implemented using resources of the R statistical environment and Plink. The application is performed using real data from 71 trios of the Southeast Brazilian population, in which affected child was defined in terms of the occurrence of one congenital heart disease, and in each of the 213 individuals, genomic data were collected using Affymetrix SNP 6.0 platform.

O grande desafio da Epidemiologia Genética, atualmente, é identificar, em um espaço de variáveis preditoras de alta dimensão e esparso, fatores de risco genéticos para doenças complexas. Um delineamento amostral útil nestes estudos é coletar dados de trios, que são pequenos núcleos familiares (pai e mãe, livres da doença, e filho afetado) e, em cada indivíduo, obter dados do genótipo de marcadores moleculares, sendo a plataforma de marcadores do tipo SNPs (do inglês, Single Nucleotide Polymorphism), com cerca de 1 milhão de variáveis preditoras genéticas, a mais adotada. Neste trabalho é proposto um procedimento em múltiplos estágios para identificar SNPs associados com a doença em dados de trios. A primeira etapa do procedimento é baseada em uma série de análises unilocos (para cada variável preditora), usando um teste de simetria em tabelas de contingência 2 x 2 (conhecido, em Genética, como teste TDT, do inglês, Transmission Disequilibrium Test). Em um segundo estágio da análise, os resultados destes testes são usados para construir uma estatística de somas acumuladas padronizadas (CUSUM) que permite a seleção de conjuntos de SNPs (isto é, conjuntos de variáveis preditoras), possivelmente associados com a doença. Como um terceiro passo da análise, nas regiões selecionadas no passo dois, são realizadas análises de simetria via testes exatos considerando tabelas 2 x 2 e 4 x 4 (pares de SNPs). A formulação do TDT em termos de testes de simetria é uma inovação na área de Genética e facilita a extensão do caso uniloco para o multilocos. A contribuição deste trabalho reside ainda na formulação exata do teste que é útil em situações de amostras pequenas que ocorrem com frequência em dados de trios. Neste caso inferências parciais foram realizadas a partir de decomposições apropriadas da função de verossimilhança. A modelagem do problema em termos do modelo logístico permitiu concluir que não é necessário corrigir a associação para o efeito de covariáveis avaliadas nos pais. O procedimento é implementado usando recursos dos aplicativos PLINK e R. A aplicação é realizada utilizando dados de 71 trios da população brasileira, em que os indivíduos caso (filhos) foram definidos em termos da ocorrência de uma cardiopatia e, em cada um dos 213 indivíduos, estão disponíveis dados genéticos de uma plataforma de SNPs. / Currently, the great challenge of Genetic Epidemiology is to identify, in a high dimensional and sparse space of predictor variables, genetic risk factors for complex diseases. A useful sampling design in these studies is to collect data from trios, which are small nuclear families (father and mother, free from disease, and affected child), and obtain genotypic information from each individual. The molecular markers platform most commonly used for this purpose is of SNPs (Single Nucleotide Polymorphisms), with about 1 million genetic predictor variables. This work proposes a multi-stage procedure to identify SNPs associated with disease using data from trios. The first step of the procedure is based on a series of single locus analysis (for each predictor variable) using a test for symmetry in 2 x 2 contingency tables (known in genetics as TDT (Transmission Disequilibrium Test). In a second stage of the analysis, the results of these tests are used to construct a standard statistic of the cumulative sums (CUSUM), which allows the selection of sets of adjacent SNPs (ie, sets of predictor variables), possibly associated with the disease. As a third step of the analysis, in the regions selected in step two, are performed an extended analysis of symmetry considering 4 x 4 contingency tables. The TDT formulation in terms of symmetry tests is an innovation in the genetics area and facilitates the extension of the single locus analysis to the multiloci case. The contribution of this work lies in the exact formulation of the symmetry test for square contingency tables that is useful in situations of small sample sizes that often occur in data from trios. In this case, partial inferences were performed from appropriate decompositions of the likelihood function. The structural modeling of the problem in terms of logistic model allowed us to conclude that there is no need to adjust the association for data from parents, but only for the effect of covariates evaluated in each parental haplotype. The procedure is implemented using resources of the R statistical environment and Plink. The application is performed using real data from 71 trios of the Southeast Brazilian population, in which affected child was defined in terms of the occurrence of one congenital heart disease, and in each of the 213 individuals, genomic data were collected using Affymetrix SNP 6.0 platform.

L'objectif de ce travail de thèse est le développement d'une approximation polynomiale axiale dans un solveur basé sur la Méthode des Caractéristiques. Le contexte, est celui de la solution stationnaire de l'équation de transport des neutrons pour des systèmes critiques, et l'implémentation pratique a été réalisée dans le solveur "Two/three Dimensional Transport" (TDT), faisant partie du projet APOLLO3®. Un solveur MOC pour des géométries en trois dimensions a été implémenté dans ce code pendant un projet de thèse antécédent, se basant sur une approximation constante par morceaux du flux et des sources des neutrons. Les développements présentés dans la suite représentent la continuation naturelle de ce travail. Les solveurs MOC en trois dimensions sont capables de produire des résultats précis pour des géométries complexes. Bien que précis, le coût computationnel associé à ce type de solveur est très important. Une représentation polynomiale en direction axiale du flux angulaire des neutrons a été utilisée pour réduire ce coût computationnel.Le travail réalisé pendant cette thèse peut être considéré comme divisé en trois parties: transport, accélération et autres. La première partie est constituée par l'implémentation de l'approximation polynomiale choisie dans les équations de transmission et de bilan typiques de la Méthode des Caractéristiques. Cette partie a aussi été caractérisée par le calcul d'une série de coefficients numériques qui se sont révélés nécessaires afin d'obtenir un algorithme stable. Pendant la deuxième partie, on a modifié et implémenté la solution des équations de la méthode d'accélération DPN. Cette méthode était déjà utilisée pour l'accélération et des itérations internes et externes dans TDT pour les solveurs deux et trois dimensionnels avec l'approximation des flux plat, quand ce travail a commencé. L'introduction d'une approximation polynomiale a demandé plusieurs développements numériques regardant la méthode d'accélération. Dans la dernière partie de ce travail on a recherché des solutions pour un mélange de différents problèmes liés aux premières deux parties. En premier lieux, on a eu à faire avec des instabilités numériques associées à une discrétisation spatiale ou angulaire pas suffisamment précise, soit pour la partie transport que pour la partie d'accélération. Ensuite, on a essayé d'utiliser différentes méthodes pour réduire l'empreinte mémoire des coefficients d'accélération. L'approche qu'on a finalement choisie se base sur une régression non-linéaire au sens des moindres carrés de la dépendance en fonction des sections efficaces typique de ces coefficients. L'approche standard consiste dans le stockage d'une série de coefficients pour chaque groupe d'énergie. La méthode de régression permet de remplacer cette information avec une série de coefficients calculés pendant la régression qui sont utilisés pour reconstruire les matrices d'accélération au cours des itérations. Cette procédure ajoute un certain coût computationnel à la méthode, mais nous pensons que la réduction de la mémoire rende ce surcoût acceptable.En conclusion, le travail réalisé a été concentré sur l'application d'une simple approximation polynomiale avec l'objectif de réduire le coût computationnel et l'empreinte mémoire associées à un solveur basée sur la Méthodes des Caractéristiques qui est utilisé pour calculer le flux neutroniques pour des géométries à trois dimensions extrudées. Même si cela ne constitue pas une amélioration radicale des performances, l'approximation d'ordre supérieur qu'on a introduit permet une réduction en termes de mémoire et de temps de calcul d'un facteur compris entre 2 et 5, selon le cas. Nous pensons que ces résultats constitueront une base fertile pour des futures améliorations. / The purpose of this PhD is the implementation of an axial polynomial approximation in a three-dimensional Method Of Characteristics (MOC) based solver. The context of the work is the solution of the steady state Neutron Transport Equation for critical systems, and the practical implementation has been realized in the Two/three Dimensional Transport (TDT) solver, as a part of the APOLLO3® project. A three-dimensional MOC solver for 3D extruded geometries has been implemented in this code during a previous PhD project, relying on a piecewise constant approximation for the neutrons fluxes and sources. The developments presented in the following represent the natural continuation of this work. Three-dimensional neutron transport MOC solvers are able to produce accurate results for complex geometries. However accurate, the computational cost associated to this kind of solvers is very important. An axial polynomial representation of the neutron angular fluxes has been used to lighten this computational burden.The work realized during this PhD can be considered divided in three major parts: transport, acceleration and others. The first part is constituted by the implementation of the chosen polynomial approximation in the transmission and balance equations typical of the Method Of Characteristics. This part was also characterized by the computation of a set of numerical coefficients which revealed to be necessary in order to obtain a stable algorithm. During the second part, we modified and implemented the solution of the equations of the DPN synthetic acceleration. This method was already used for the acceleration of both inners and outers iteration in TDT for the two and three dimensional solvers at the beginning of this work. The introduction of a polynomial approximation required several equations manipulations and associated numerical developments. In the last part of this work we have looked for the solutions of a mixture of different issues associated to the first two parts. Firstly, we had to deal with some numerical instabilities associated to a poor numerical spatial or angular discretization, both for the transport and for the acceleration methods. Secondly, we tried different methods to reduce the memory footprint of the acceleration coefficients. The approach that we have eventually chosen relies on a non-linear least square fitting of the cross sections dependence of such coefficients. The default approach consists in storing one set of coefficients per each energy group. The fit method allows replacing this information with a set of coefficients computed during the regression procedure that are used to re-construct the acceleration matrices on-the-fly. This procedure of course adds some computational cost to the method, but we believe that the reduction in terms of memory makes it worth it.In conclusion, the work realized has focused on applying a simple polynomial approximation in order to reduce the computational cost and memory footprint associated to a Method Of Characteristics solver used to compute the neutron fluxes in three dimensional extruded geometries. Even if this does not a constitute a radical improvement, the high order approximation that we have introduced allows a reduction in terms of memory and computational times of a factor between 2 and 5, depending on the case. We think that these results will constitute a fertile base for further improvements.

El objetivo principal del proyecto de tesis doctoral es proponer y evaluar soluciones técnicas compatibles con la familia de estándares DVB diseñados para redes TDT que permitan por un lado, la transmisión simultánea de contenidos de TV a receptores fijos y móviles en configuraciones de red con alta capacidad de transmisión, y por otro lado la e ficiente provisión de contenidos locales en topologías SFN. Esta propuesta de tesis está dividida en tres secciones. La primera sección consiste en una revisión del estado del arte respecto a la planificación y diseño de redes de TDT que utilizan los estándares DVB, las soluciones propuestas e implementadas a día de hoy para la provisión de contenidos de TV digital a terminales móviles a través de las infraestructuras de TDT; así como las técnicas de transmisión utilizadas para la provisión de contenidos locales en redes de TDT, las soluciones propuestas en el estándar de segunda generación DVB-T2 y los requerimientos técnicos del futuro estándar DVB-NGH para la e ficiente emisión de estos contenidos en topologías de red SFN. Con base en el estado del arte se de ne en la segunda sección el objetivo principal, los objetivos específicos y los resultados esperados en el desarrollo de la tesis doctoral. Finalmente en la tercera sección se describe la metodología y los escenarios de evaluación que se utilizarán en las diferentes etapas del proceso de investigación. / López Sánchez, J. (2014). Transmisión Eficiente de Servicios Fijos/Móviles y Servicios Locales en Redes de Televisión Digital Terrestre de Primera y Segunda Generación [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/35134 / TESIS

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.