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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
761

Développement et mise en œuvre d’un mécanisme « 4D-addressing Wakeup radio » pour la réduction de la consommation d’énergie dans les réseaux de capteurs sans fil / Development and implementation of a "4D-addressing wakeup radio" mechanism for the reduction of energy consumption in wireless sensor networks

Antilahy, Herimpitia Tsilavina Chrystelle 27 August 2018 (has links)
Les réseaux de capteurs sans fil qui conviennent pour vaste domaine d’applications, constituent une solution prometteuse qui répond à toute exigence de surveillance continue. L’autonomie énergétique des nœuds constitue un facteur de vulnérabilité qui influe directement leur longévité et la capacité du réseau à assurer longuement la couverture d’une zone géographique d’intérêt. La gestion de consommation énergétique représente la seule approche pour accroître la durée de vie de ces réseaux et leur conférer une autonomie raisonnable. Des solutions logicielles proposées à travers les protocoles MAC, apportent des améliorations significatives à la minimisation de la dépense énergétique des nœuds. Elles permettent de réduire les périodes d’écoute du canal qui, représente l’opération la plus coûteuse en termes d’énergie dans le fonctionnement des nœuds de capteurs sans fil. Néanmoins, se limiter à ces solutions n’est pas suffisant pour garantir une longévité acceptable. La seule méthode pour optimiser la conservation d’énergie dans les RCSFs est de mettre chaque nœud constamment en mode faible puissance et d’utiliser un mécanisme de télé-réveil à travers des signaux de réveil. Cela implique, l’utilisation de circuits de réveil de faible consommation qui assurent la surveillance de canal et qui déclenchent le réveil des nœuds uniquement à chaque fois qu’événement d’intérêt se produit. Dans ce contexte, une quantité importante de travaux ont proposés l’utilisation d’un mécanisme d’adressage (adresses MAC ou d’autres informations binaires), pour permettre aux nœuds non concernés de retourner rapidement dans son état de sommeil. Cette démarche est intéressante, mais implique toutefois une dépense énergétique non négligeable, liée à la réception et au traitement des informations d’adresse au niveau de tous les nœuds. La solution la plus efficace énergétiquement serait l’utilisation d’une autre forme d’adresse. Cette thèse s’inscrit dans le contexte de minimisation de la consommation énergétique des RCSFs par la mise en œuvre d’un adressage qui permet aux nœuds de recevoir et de traiter les signaux de réveil, sans allumer leur module de communication principal. Il s’agit pour nous de supprimer la dépense énergétique liée à l’allumage du module RF et à la réception de paquets d’adresse, en se tournant vers l’exploitation de la durée des signaux de réveils. Notre solution se repose sur les caractéristiques matérielles du microcontrôleur (IRQ, Timer/Counter) des nœuds de capteurs. Elle permet de réduire les complexités liées aux conditionnements des signaux de réveils. Notre solution est implémentée sur un réseau de petite taille. Elle est évaluée expérimentalement et ses performances énergétiques sont comparées à celles d’un schéma classique de télé-réveil sans mécanisme d’adressage et à celles d’un schéma classique basé sur le duty-cycling. / Wireless sensor networks that are suitable for a wide range of applications, represent a promising solution that meets any requirement for continuous monitoring. The energy autonomy of sensor nodes constitutes a vulnerability factor that directly affects their longevity and the capacity of the network to ensure long coverage of the geographical area of interest. Energy consumption management is the only way to increase the lifespan of these networks and to give them a reasonable autonomy. Software solutions proposed through MAC protocols, bring significant improvements to the minimization of the energy expenditure of sensor nodes. They reduce the idle-listening periods which represents the most expensive operation in terms of energy, in the operation of the wireless sensor nodes. However, Focusing lonely on these solutions is not enough to guarantee acceptable longevity. The only way to optimize energy conservation in the WSN is to constantly put each node in low power mode and use a wakeup mechanism through wake-up signals. This involves the use of low-power wake-up circuits that provide channel monitoring, and trigger node wake-up only whenever event of interest occurs. In this context, a significant amount of work has proposed the use of an addressing mechanism (MAC addresses or other binary informations), to allow non-concerned nodes to quickly return to their sleep state. This approach is interesting, but involves a significant energy expenditure, related to address information’s reception and processing at all nodes. The most energy efficient solution would be the use of another type of address. This thesis is part of the context of minimizing the energy consumption of the WSN, using an addressing system that allows sensor nodes to receive and process the wake-up signals, without turning on their main communication module. It is to eliminate the energy expenditure related to the RF module’s activation and the reception of address packets, by exploiting wakeup signals duration. Our solution is based on the hardware characteristics of the microcontroller (IRQ, Timer/Counter) of sensor nodes. It reduces the complexities related to wakeup signals conditioning. Our solution is implemented on a small network. Its evaluations were done experimentally and its energy performance is compared to a conventional wake-up mechanism without addressing,and a conventional scheme based on duty-cycling.
762

Essays on the interaction between migration and sending communities : evidence from China and Vietnam / Essais sur l’interaction entre migration et communautés d’origine : les cas de la Chine et du Vietnam

Xu, Hui 30 September 2011 (has links)
Cette thèse comporte trois chapitres qui se rattachent aux relations entre les migrants et leur communauté d'origine sur le cas de la Chine et le Vietnam. Le premier chapitre étudie la relation entre les transferts de fonds envoyés par les migrants, et le niveau de confiance et de fiabilité des villageois vietnamiens qui en sont bénéficiaires. Voici les résultats principaux obtenus en combinant les données d’un terrain d’expérimentation de 2010 avec les données de VHLSS 2002 (2002 Vietnam Household Living Standard Survey). En ce qui concerne le niveau de confiance, cette étude montre que les transferts de fonds internationaux sont liés de manière positive au comportement de confiance de ceux qui les reçoivent. En ce qui concerne le niveau de fiabilité, l’étude trouve que les transferts de fonds internationaux ont un lien négatif avec le niveau de fiabilité de celui qui les reçoit tandis que les transferts de fonds internes ont un lien positif avec le niveau de fiabilité de celui qui les reçoit. Cette étude montre en outre que le niveau de fiabilité est plus élevé dans le sud que dans le nord de Vietnam. Le deuxième chapitre s'interroge sur l'impact des enfants lassés dans la communauté d’origine par les migrants sur leur décision de retour en Chine en utilisant une enquête ménage en milieu rural du district de Wuwei (dans la province de l’Anhui) en 2008. Un modèle de durée paramétrique à hasards proportionnels en temps discret et un modèle probit sont employés pour estimer séparément le rôle des enfants laissés au village par âge et par sexe sur la longueur des épisodes migratoires pour les migrants actuels et les migrants du retour, ainsi que pour les intentions de retour de migrants actuels. Cette étude souligne le rôle des enfants lassés derrières comme raison significative pour le retour des parents migrants. Le dernier chapitre étudie l’impact de l’expérience migratoire sur le choix d’être entrepreneur pour un migrant du retour après son retour dans sa communauté d’origine. En utilisant la même base de donnés chinoise, cette étude montre que les migrants du retour ont une tendance plus affirmée à devenir entrepreneurs que les non-migrants, et que l'épargne rapatriée par les migrants, comme la fréquence des changements d'emploi pendant l'épisode migratoire, exercent une influence positive sur la probabilité des migrants de devenir entrepreneurs après leur retour. / This dissertation is comprised of three chapters on the interaction between migrants and their source regions applied to China and Vietnam. The first chapter examines whether remittances are related to receivers’ trust and trustworthiness in Vietnam. Using a combination of a field experiment conducted in 2010 and the “2002 Vietnam Household Living Standards Survey”, the chapter finds that while internal remittances have no significant relationship to trusting behavior, international remittances demonstrate a significantly positive connection. On the other hand, international remittances are negatively related to trustworthiness, while internal remittances are positively associated. Besides, this study finds that the level of trustworthiness is higher in the south than in the north. The second chapter explores the role of children by age and by gender as a motive for return migration in China by using a rural household survey conducted in Wuwei County (Anhui province) in 2008. Resorting to a discrete time proportional hazard model and a binary Probit model to estimate respectively the determinants of migration duration for both on-going migrants and return migrants, and the return intentions of on-going migrants, the chapter finds consistent results regarding the role of left-behind children as a significant motive for return. The last chapter examines the impact of the migration experience on individuals’ choice of being self-employed upon their return to their home villages. By using the same data of Wuwei survey, the chapter finds that return migrants are more likely to be self-employed than non-migrants, and that both return savings and the frequency of job changes during migration increase the likelihood for return migrants to become self-employed.
763

Resposta dinâmica dos motores de indução trifásicos a afundamentos de tensão na rede de alimentação / Dynamic response of three-phase induction motors to voltage sags in the power supply network

Gerson Bessa Gibelli 04 June 2009 (has links)
Esta pesquisa apresenta um estudo da resposta dinâmica dos motores de indução trifásicos submetidos a afundamentos de tensão. As simulações computacionais sobre um sistema de distribuição, assim como a modelagem dos motores de indução trifásicos baseada em dados reais, foram realizadas utilizando-se do software ATP (Alternative Transients Program). Estas tiveram por objetivo gerar situações representativas da operação do sistema elétrico de potência (SEP), caracterizando afundamentos de tensão, fenômenos estes pertencentes à classe de variações de tensão de curta duração (VTCD), no contexto da qualidade da energia elétrica (QEE). Da observação destes afundamentos, verificaram-se as situações que vieram ou não, a comprometer a alimentação do equipamento analisado e, conseqüentemente, seu desempenho. Pelos resultados observados, evidencia-se que a metodologia de análise aplicada é satisfatória e condizente com o encontrado em situações reais de operação dos motores de indução trifásicos, denotando certas características intrínsecas no contexto das VTCDs. / This research shows a study on the dynamic response of three-phase induction motors submitted to voltage sags. Computer simulations about a distribution system, as well as the modeling of three-phase induction motors based on actual data, were made using ATP (Alternative Transients Program) software. These simulations intended to generate representative situations of the electrical power system (EPS) operation, characterizing voltage sags, which is a phenomenon belonging to the class of short duration voltage variations (SDVV), in the electrical power quality context (EPQ). From the observation of these sags, we verified the situations that jeopardized or not the supply of the analyzed equipment and, consequently, its performance. From the observed results, it becomes evident that the methodology of the applied analysis is satisfactory and in agreement with the one found in actual situations of three-phase induction motors operations, indicating certain characteristics intrinsic to the SDVV context.
764

Mitigação de variações de tensão causadas pela proteção anti-ilhamento de geradores distribuídos via controle de taps de reguladores de tensão / Mitigating voltage variations caused by the anti-islanding protection of distributed generator via voltage regulator tap control

Daniel Ferreira Lima 04 August 2017 (has links)
A conexão de geradores distribuídos em sistemas de distribuição deve ser cuidadosamente avaliada para que os mesmos auxiliem efetivamente na melhoria do desempenho das redes elétricas, buscando reduzir ou eliminar eventuais situações que causem a degradação da qualidade da energia elétrica fornecida aos consumidores, entre outros aspectos. Neste contexto, existem vários trabalhos que analisam a influência da conexão de geradores distribuídos no perfil de tensão da rede elétrica, frequência, desequilíbrio de fases e distorção harmônica. No entanto, há poucos trabalhos analisando os efeitos da desconexão de geradores distribuídos na qualidade da energia fornecida aos consumidores. Uma vez operando em paralelo com a rede de distribuição, esses geradores influenciam o perfil de tensão e o comportamento dos dispositivos reguladores de tensão. Como consequência, sua desconexão pode provocar variações de tensão intensas causando danos ou mau funcionamento às cargas. A desconexão pode ser repentina ou devido à atuação da proteção anti-ilhamento, seguida dos procedimentos de religamento automático do alimentador, se houver. Visando estudar este problema, o qual tende a se tornar uma nova preocupação das concessionárias de energia elétrica, e no intuito de minimizar e/ou eliminar os possíveis efeitos negativos dessas variações de tensão, esta pesquisa propõe o desenvolvimento de um método de controle dos taps dos reguladores de tensão. Neste método, o controle dos taps foi modelado como um problema de otimização, minimizando as violações de tensão mencionadas anteriormente e também a quantidade de operações dos reguladores de tensão ao longo de um dia típico. A otimização foi solucionada com um Algoritmo Genético e os resultados obtidos indicaram que é possível minimizar as variações de tensão usando a curva de carga do sistema para planejar a operação dos reguladores de tensão. / The connection of distributed generators in an electric power system should be evaluated carefully to ensure that they effectively assist in improving the performance of electrical networks, reducing or eliminating any situations that cause degradation of the power quality of the consumers, and other issues. In this context, there are several studies that analyze the influence of generators connected to distribution systems and how they affect the frequency, cause variations in voltage magnitude, voltage unbalance and harmonic distortion. However, there are a few studies analyzing the effects that the disconnection of distributed generators induces to the power quality of consumers. Once operating in parallel with the distribution network, these generators have an effect on voltage variations and voltage regulator devices. As a result, disconnection can cause severe voltage variations causing damage or malfunction to the loads. The disconnection may be sudden or due to the action of anti-islanding protection, followed by the procedure to reconnect the substation, if it is possible. In order to study this problem, which tends to become a new power quality concern for electric utilities, and in order to minimize and / or eliminate the possible side effects of the voltage variations, this research proposes the development of a control method of voltage regulators\' taps. In this method, the control of taps was modeled as an optimization problem which aimed to minimize these voltage variations aforementioned and also the amount of voltage regulator operations over a typical day. The optimization was solved by a Genetic Algorithm and the results obtained demonstrate that it is possible to minimize the voltage variation by using the system load curve to plan the operation of voltage regulators.
765

Características morfogênicas e estruturais da braquiária xaraés e do estilosantes mineirão / Brachiaria xaraes and stylosanthes mineirão morphogenetic and structural characteristics

Sousa, Renata Rodrigues Jardim 15 August 2012 (has links)
Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-10-06T13:52:31Z No. of bitstreams: 2 Dissertação Renata Jardim.pdf: 620239 bytes, checksum: dbbb756833afca246328749e9e3946cf (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-10-06T15:44:58Z (GMT) No. of bitstreams: 2 Dissertação Renata Jardim.pdf: 620239 bytes, checksum: dbbb756833afca246328749e9e3946cf (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-10-06T15:44:58Z (GMT). No. of bitstreams: 2 Dissertação Renata Jardim.pdf: 620239 bytes, checksum: dbbb756833afca246328749e9e3946cf (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2012-08-15 / This study aimed to evaluate the morphogenetic and structural characteristics of the Brachiaria brizantha cv. Xaraés and Stylosanthes guianensis var. vulgaris cv. Mineirão at Jataí Campus of Federal University of Goiás. The experimental design was the randomized complete block with three planting systems (Xaraés and Estilosantes both single and both intercropped) under three phosphorus levels (low, medium and high - 70, 105 and 140 kg/ha P2O5) applied at sowing with four replications. Data analysis was performed in a split plot model, considering in the plot, the planting system, the block and the evaluation period and at the split plot the dose effect and the interaction between planting system and dose. The means comparison was performed by “t” test at 5% of probability, using SAS® program version 9.0. The phosphorus doses and planting systems did not influence the morphogenetic and structural characteristics of the Brachiaria brizantha cv. Xaraés. The best results of leaf appearance rate, phyllochron, branching elongation rate, leaf enlargement rate, primary branches number, secondary branches number, leaflets length and width for the Stylosanthes guianensis var. vulgaris cv. Mineirão were verified in the single planting system. Independent of the planting system evaluated, the low (70 kg/ha P2O5) and medium (105 kg/ha P2O5) phosphorus doses have provided higher leaf elongation rate and petiole elongation rate for the Mineirão. The higher phosphorus dose (140 kg/ha P2O5) yielded lower elongation petiole rate for the Mineirão in the intercropped system and longer leaflets. / Objetivou-se com este trabalho avaliar as características morfogênicas e estruturais da Brachiaria brizantha cv. Xaraés e do Stylosanthes guianensis var. vulgaris cv. Mineirão no Campus Jataí da Universidade Federal de Goiás. O delineamento utilizado foi o de blocos completos ao acaso, com três arranjos de plantio (Xaraés e Estilosantes solteiros e consorciados) associado a três doses de fósforo (baixa, média e alta - 70, 105 e 140 kg/ha de P2O5) aplicadas na semeadura, com quatro repetições. A análise dos dados foi realizada em parcela subdividida considerando o efeito do arranjo de plantio, bloco e período de avaliação na parcela e efeito da dose e interação de arranjo de plantio e dose na subparcela. A comparação das médias foi realizada pelo teste t a 5% de probabilidade, utilizando o programa SAS® versão 9.0. Arranjos de plantio e doses de fósforo não influenciaram (P>0,05) as características morfogênicas e estruturais da Brachiaria brizantha cv. Xaraés. Por outro lado, influenciaram (P<0,05) as características do estilosantes. Os melhores resultados para taxa de aparecimento de folhas, filocrono, taxa de alongamento de ramificação, taxa de alargamento de folha, número de ramificações primárias, número de ramificações secundárias, comprimento de folíolos e largura de folíolos do Stylosanthes guianensis var. vulgaris cv. Mineirão foram verificados no plantio solteiro. As doses baixa (70 kg/ha de P2O5) e média (105 kg/ha de P2O5) de fósforo proporcionam as maiores taxas de alongamento de folha e de alongamento de pecíolos do estilosantes Mineirão independente do arranjo de plantio avaliado. A dose alta de fósforo (140 kg/ha de P2O5) proporciona menor taxa de alongamento de pecíolos do estilosantes Mineirão no plantio consorciado. A dose alta de fósforo proporcionou maior comprimento de folíolos do estilosantes Mineirão.
766

Estimador de variações de tensão de curta duração em sistemas elétricos de potência utilizando estratégias evolutivas. / Estimate short duration voltage variation using evolutionary strategies.

Wilingthon Guerra Zvietcovich 19 September 2011 (has links)
Neste trabalho, é proposta uma metodologia para estimar o estado de um sistema elétrico de potência (SEPs) durante variações de tensão de curta duração (VTCDs) causadas por faltas elétricas nas linhas que compõem a rede elétrica avaliada. Para cumprir esta meta, são utilizados os valores registrados nos equipamentos de medição instalados nas redes elétricas. Na realidade, existem poucos equipamentos nas redes elétricas devido aos custos elevados dos medidores de qualidade de energia elétrica (QEE). Embora estes custos tenham diminuído nos últimos anos, ainda é inviável a utilização de um número suficiente de medidores para garantir a monitoração de toda a rede, por tornar-se muito oneroso. Esta realidade constitui um desafio para se desenvolver técnicas que permitam, a partir de um pequeno número de pontos de monitoração, determinar os locais de faltas e estimar os valores das VTCDs em todas as barras que compõem um sistema elétrico. Como contribuição à solução destes problemas, esta tese propõe a utilização do algoritmo denominado Estratégias Evolutivas (EEs), que integra a família dos Algoritmos Evolutivos. Tal algoritmo mostrou ser viável por sua facilidade de implementação e rapidez de resposta na busca de uma solução dentro de um vasto espaço de soluções. As EEs, nesta tese, são utilizadas para se determinar: o local de falta, tipo de falta e impedância de falta, que caracterizam um indivíduo, de forma que as tensões resultantes nas barras monitoradas sejam as mais próximas possíveis das medições realizadas. Para alcançar esse objetivo, inicialmente se constrói uma população inicial de indivíduos que representam alternativas de solução do problema. Em seguida, uma parte destes indivíduos será submetida a mutação e recombinação para então serem selecionados os indivíduos que sobreviverão na geração futura. Este processo iterativo é realizado até que se encontre uma solução o mais próximo da procurada. Cada indivíduo é avaliado através de função objetivo, que representa o erro quadrático entre os valores medidos e os valores calculados. Para este cálculo, é necessário simular um curto-circuito com as características do indivíduo avaliado com base em informações da rede bem como dos valores das tensões provenientes dos medidores. A partir da determinação das características da falta, é feita a estimação dos valores das tensões em toda a rede levando à avaliação das VTCDs. Uma vez atingido este objetivo, é possível, por exemplo, determinar indicadores de qualidade associados às VTCDs, como o SARFI (System Average RMS Frequency Index), determinar as áreas mais propensas a causar as VTCDs e elaborar planos de manutenção preventiva. Foram implementados dois algoritmos que calculam o número mínimo de medidores e os locais onde estes devem ser instalados. O primeiro algoritmo tem a finalidade de garantir o monitoramento de toda a rede em relação às VTCDs enquanto o segundo garante o menor erro de estimação de VTCDs nas barras onde não se têm medidores instalados. A referida metodologia pode ser aplicada em redes radiais ou em malha, sendo inicialmente aplicada em sistemas de pequeno porte (redes de 14 e 30 barras do IEEE) com intuito de verificar a capacidade do algoritmo. Foram então simuladas redes de maior complexidade, por meio de testes em redes de 57 barras e 118 barras do IEEE. Para avaliar a eficiência da metodologia desenvolvida foi feita uma comparação com outra metodologia de otimização baseada em Algoritmos Genéticos (AGs). / A methodology is herein proposed to estimate Short Duration Voltage Variation (SDVV) in electric power systems, caused by electrical faults. To attain this target, values recorded by measurement equipment in specific sites are used. In fact, there are few power quality meters installed in power networks, due to the high cost of such meters. Although these costs have decreased in recent years, the installation of a sufficient number of meters to ensure monitoring the entire network is still unfeasible. This reality poses a challenge to developing techniques that, with a small number of monitoring points, allow the determination of fault locations and estimation of SDVV values in specified buses. As contribution this thesis proposes an algorithm called Evolutionary Strategies (ESE), which integrates the group of evolutionary algorithms. This algorithm can be easily implemented and finds a solution within a wide solution space. The ESE determines the fault location, fault type and fault impedance, that characterize an individual, so that the resulting voltages on monitored buses are as close as possible to the measured ones. An initial population is generated as alternative solutions to the problem. Some of the individuals in the population will be submitted to mutation and recombination operators. Individuals are then selected to the future generation. An iterative process is carried out to determine a solution as close as possible to the desired one. Each individual is evaluated by the objective function, which represents the quadratic error between the measured and calculated values. This calculation is based on short circuit calculation related to the evaluated individual and from information of voltage values gathered from power quality meters. Voltage values in specific network buses can then be determined to monitor their corresponding SDVV values. This allows, for example, determining quality indicators associated to the SDVV, such as the System Average RMS Frequency Index (SARFI), to evaluate sensitive areas, i.e. which are prone to cause SDVVs and to develop plans for preventive maintenance. Two algorithms that calculate the minimum number of meters and their locations have been implemented. The first algorithm aims to ensure monitoring the entire network regarding SDVVs, while the second algorithm ensures the smallest error of SDVV estimation in buses where no meters are installed. This methodology can be applied to meshed or radial networks. It was initially implemented in small networks (IEEE 14 and 30 buses) with the purpose of verifying the ability of algorithm. In sequence the methodology was applied to more complex networks (IEEE 57 and 118 buses). To assess the efficiency of the methodology a comparison with other optimization methodology based on Genetic Algorithms (GA) was carried out.
767

Análise da robustez e da sensibilidade de sistemas de distribuição para a alocação otimizada de medidores frente às variações de tensão de curta duração / Analysis of the robustness and sensitivity of distribution systems for optimal allocation of monitors in face of Short Duration Voltage Variations

Thais Reggina Kempner 19 May 2016 (has links)
Como as Variações de Tensão de Curta Duração (VTCDs) estão entre as perturbações mais difíceis de serem monitoradas, uma vez que são ocasionadas por fatores aleatórios e imprevisíveis, a monitoração do Sistema de Distribuição (SD) representa uma providência essencial para a obtenção de informações representativas para a regulamentação de novos indicadores relativos a esses distúrbios. Neste cenário, este trabalho busca garantir a completa observabilidade das VTCDs em SD, quando da incidência de qualquer tipo de curto-circuito, através da alocação ótima de medidores. Para a determinação da magnitude da tensão em cada nó do SD é utilizado o método das posições de falta, denotando assim, a influência e a propagação das VTCDs sobre a rede como um todo. Na sequência, é determinada uma matriz binária resultante que observa os afundamentos de tensão de forma simultânea para todos os tipos de faltas. Posteriormente, é proposta a redução desta matriz para diminuir o esforço computacional em SDs de grande porte. Ainda, é analisada a vulnerabilidade de cada nó do SD para estabelecer a sua posterior ponderação no processo de otimização. Os resultados revelam que a metodologia de alocação apresentada torna o processo de obtenção da solução ótima ágil e direto, pois menos execuções computacionais são necessárias para obter diferentes soluções ótimas e garantir a monitoração dos afundamentos de tensão para todos os tipos de curtos-circuitos. Além disso, pela metodologia, tem-se também a prioridade de instalação dos medidores conforme a maior observabilidade dos afundamentos de tensão, possibilitando a escolha do melhor arranjo de medidores que atenda aos limites orçamentários das distribuidoras de energia. / Short Duration Voltage Variations (SDVVs) are among the most difficult disturbances to be monitored, since they are caused by random and unpredictable factors. Hence, the Distribution System (DS) monitoring is an essential step for obtaining representative information for the regulation of new power quality indices for these disturbances. In this scenario, this work aims to ensure the entire observability of SDVVs, considering any short circuit occurrence in the DS, based on algorithm to achieve the monitors\' optimal allocation. In order to determine the voltage magnitude at each node, the fault positions method is used, showing the influence and propagation of SDVVs on the DS. Subsequently, a resulting binary matrix is determined. This matrix observes the voltage sags, simultaneously, for all fault types. Then, the downsizing of this matrix is proposed in order to reduce the computational effort in large DSs. Furthermore, the vulnerability of each DS node is analyzed to establish the relative weighting in the optimization process. The results show a faster and more direct allocation methodology to obtain the optimal solution, because fewer computational executions are needed for different optimal solutions and to ensure the voltage sags monitoring for all short circuits types. Moreover, the power quality monitor installation priority is performed according to the higher observability of the voltage sags, making it possible to choose the best arrangement of monitors that meets the budget constraints of the power utilities.
768

Atlas numérique Genius Loci, modélisation de connaissance à partir d’une poétique du chantier / Digital Atlas Genius Loci, knowledge modelling based on poetics of construction sites

Domengie, Céline 22 November 2018 (has links)
Cette thèse de recherche en art se déploie dans deux dimensions principales intimement liées, l’une épistémologique et l’autre artistique. Premièrement, du point de vue épistémologique, elle est l’expression du continuum entre théorie et pratique. Elle pose l’hypothèse que le méta-art initié par deux artistes : Adrian Piper dans les années 1970 et Jean-Paul Thibeau dans les années 1990, constitue la méthode idoine pour expliciter et analyser l’expérimentation artistique. Le programme théorico-pratique que nous avons conçu s’articule sur deux registres de textes : les récits d’expérience relatant quatre projets (Genius Loci Monflanquin, Genius Loci Aix, Genius Loci Villeneuve, Genius Loci UBUBM) et les commentaires analytiques relatifs aux récits d’expérience (« Comment représenter le mouvement ? », « Comment l’écosophie permet-elle d’éclairer les pratiques artistiques qui investissent le quotidien comme situation d’expérimentation ? », « Comment prendre une décision ? », et « Comment ménager des passes au milieu du milieu ? »). Deuxièmement, du point de vue artistique, cette thèse ouvre un espace d’expérimentation pour la création de l’Atlas Genius Loci. Les situations de chantier à partir desquelles nous avons travaillé (en particulier ceux des universités bordelaises) nous ont amené à pratiquer une recherche-création sur des terrains de vie concrets et à mettre en œuvre des processus de coopération artistique avec des maîtres d’ouvrage et des institutions. À partir d’une interrogation sur les articulations possibles entre l’art et les pratiques architecturales de l’industrie du bâtiment (Building Information Modelling), notre Atlas est devenu un « processus mésologique », un travail d’inter-relation au sein d’un milieu, construisant une présence-alliance entre une artiste et une institution. Le prolongement de cette recherche-création, où le terrain-milieu d’où l’on parle est à la fois explici-té dans sa matérialité et impliqué dans l’expérimentation, s’inscrit dans l’héritage de l’analyse institutionnelle (sociologie) et de la critique institutionnelle (art) pratiquée dès les années 1970. L’enjeu de ce travail porte sur les engagements contemporains de l’artiste dans la société, et réciproquement, sur la place que celle-ci réserve à l’art, il rend compte de la singularité de la recherche en art, et de la façon dont elle ouvre aujourd’hui des perspectives originales pour l’alliance du monde académique avec la société civile. / This research thesis in art unfolds in two main and closely linked dimensions, one epistemological and the other artistic. Firstly, from an epistemological point of view, it is the expression of the continuum between theory and practice. It hypothesizes that meta-art initiated by two artists: Adrian Piper in the 1970s and Jean-Paul Thibeau in the 1990s, defines the right method to explicit and analyse the artistic experimentation. This theoretical-practical program is carried out through the writing of two kinds of texts: the experience accounts of our projects (Genius Loci Monflanquin, Genius Loci Aix, Genius Loci Villeneuve, Genius Loci UBUBM) and the analytical comments ("How to represent movement? ", " How can ecosophy shed light on the artistic practices that take place in everyday life as a experimentation situation? ", "How to make a decision? ", and "How to build a pathway to the heart of a living environment?”). Secondly, from an artistic point of view, this thesis opens up a space for experimentation on the creation of the Atlas Genius Loci. The "construction site situations" from which we have worked (in particular those with Bordeaux universities) have led us to practice a research-creation on tangible living environments, and to pursue artistic cooperation with project owners and institutions. With the possible links between art and architecture (Building Information Modeling) as a starting point, our Atlas has become a "mesological process" claiming a presence-alliance between an artist and an institution. The extension of this research-creation, where the field-environment from where one speaks is both explicit in its materiality and involved in the experimentation, is part of the legacy of institutional analysis (sociology) and institutional criticism (art) practiced since the 1970s.The contemporary commitment of the artist in society, and reciprocally, the place that society gives to art, expresses the singularity of the artistical research, and the way that it now opens up original perspectives for the alliance of the academic world with civil society.
769

Associação da apneia obstrutiva do sono e da curta duração do sono com a função renal em pacientes com doença arterial coronariana / Association of obstructive sleep apnea and short sleep duration with renal function in patients with coronary artery disease

Furlan, Sofia Fontanello 26 October 2018 (has links)
Introdução: A doença arterial coronariana (DAC) constitui uma das principais causas de mortalidade mundial à despeito dos avanços no seu tratamento. Neste sentido, importantes comorbidades podem contribuir para este cenário desfavorável. Um dos fatores de pior prognóstico nos pacientes com DAC é a presença da doença renal crônica (DRC). Entre os potenciais novos candidatos para este prognóstico desfavorável, podemos citar os distúrbios do sono. Diversos estudos sugerem que a apneia obstrutiva do sono (AOS) e a curta duração do sono (CDS) isoladamente estão associados com piores desfechos cardiovasculares, incluindo uma maior incidência de DAC. No entanto, não está claro se a interação da AOS com a CDS está associada com pior função renal e com maior taxa de DRC em pacientes com DAC bem como maior taxa combinada de eventos cardiovasculares e não cardiovasculares. Métodos: Foram recrutados pacientes consecutivos com DAC estabelecida (pacientes com indicação clínica para a intervenção coronária percutânea, ICP) eletiva. Após a realização da ICP com implante de stent com sucesso (estenose residual < 20% e fluxo TIMI 2- 3), todos os pacientes foram submetidos à monitorização do sono com a poligrafia portátil (Embletta Gold®) por uma noite (ainda durante a internação hospitalar) e à actigrafia de pulso (Actiwatch 2, Respironics®) durante sete dias (após o retorno do paciente às atividades habituais). Definimos a AOS por um índice de apneia-hipopneia (IAH) >=15 eventos/hora e a CDS por <6 horas por noite de sono. Nós estratificamos a associação da AOS, da CDS e a interação de ambas baseada na taxa de filtração glomerular (TFG) e a presença de DRC com exame de creatinina coletado pré-ICP. Estimamos a TFG usando a equação do Chronic Kidney Disease: Epidemiology Consortium (CKD-EPI) de forma contínua e categorizada em dois níveis: TFG < 60mL/min/1.73 m2 (diminuição moderada a grave) e TFG > 60mL/min/1.73 m2 (normal ou levemente diminuído). Após o exame do sono, o seguimento clínico foi realizado por meio de ligações telefônicas e checagem dos prontuários com 1 mês, 6 meses e depois anualmente procurando avaliar a ocorrência de eventos cardiovasculares fatais e não fatais de forma sistematizada. Resultados: Foram estudados 262 pacientes (64,1% sexo masculino, idade média: 63±10 anos e índice de massa corpórea [IMC] 27,8±4,4 Kg/m2). A frequência da AOS e CDS foi de 58,4% e 25,6%, respectivamente. Pacientes com AOS apresentaram pior TFG em relação aos pacientes sem AOS (62±26 vs. 74±20 mL/min/1,73m2, p < 0,001) e consequentemente maior taxa de DRC (42,1 vs. 26,6%, p=0,009). Em contraste, a TFG foi similar nos pacientes com e sem CDS (65±29 vs. 68±23 mL/min/1,73m2, p=0,38) e uma frequência não significante de DRC (44.8 vs. 32.5%, p=0.07). Na análise multivariada, AOS, mas não a CDS, foi independentemente associada com a TFG: beta= -10,57 (-16,46 - - 4,68), p < 0,001) e com a DRC (OR=1,95; 95% IC=1,12-3.38, p=0,01). As interações da AOS e da CDS com a TFG e a presença da DRC não foram significantes. Os resultados permaneceram similares após avaliarmos a AOS (pelo IAH) e a duração do sono de forma continua ou ao classificarmos a CDS como < 5 horas. Em uma análise exploratória, após seguimento mediano foi de 25 meses, ocorreram 43 eventos cardiovasculares (15 infartos agudos do miocárdio; 1 revascularização do miocárdio; 6 acidentes vasculares cerebrais; 7 óbitos cardiovasculares e 14 reestenoses de stent). Considerando os eventos combinados, não encontramos até o momento diferenças significantes entre os grupos com AOS e CDS quando comparados aos respectivos grupos sem estes distúrbios. Conclusão: Em pacientes com DAC, a AOS, mas não a CDS, foi independentemente associada com pior TFG e DRC, marcadores de pior prognóstico nestes pacientes / Introduction: Coronary artery disease (CAD) is one of the main causes of worldwide mortality despite advances in the medical treatment. In this sense, important comorbidities can contribute to this unfavorable scenario. One of the factors associated with poor prognosis in patients with CAD is the presence of chronic kidney disease (CKD). Sleep disorders are potential new candidates contributing to poor prognosis in CAD as well. Although not consistent, several studies suggested that obstructive sleep apnea (OSA) or short sleep duration (SSD) are associated with a higher prevalence of CAD and poor cardiovascular outcomes, including higher CAD incidence. However, it is unclear whether the interaction of OSA with SSD is associated with lower renal function and higher frequency of CKD in patients with established CAD, as well as with increased rate of cardiovascular and non-cardiovascular events. Methods: Consecutive patients with established CAD (those with clinical indication for elective percutaneous coronary intervention, PCI) were recruited. After a successful PCI procedure (residual stenosis < 20% and TIMI 2-3 flow), all patients underwent sleep monitoring with portable polygraphy (Embletta Gold®) for one night (during hospital stay) and wrist actigraphy (Actiwatch 2, Respironics®) for seven days (after patient return to usual activities). We defined OSA by an apnea-hypopnea index (AHI) >= 15 events / hour and SSD for < 6 hours per night of sleep. We stratified the association of OSA, SSD and their interaction based on the eGFR and the presence of CKD with the creatinine collected pre PCI procedure. We estimated eGFR using the Chronic Kidney Disease: Epidemiology Consortium (CKD-EPI) equations and categorized into two levels: eGFR < 60mL / min / 1.73 m2 (moderate to severe decrease) and eGFR > 60mL / min / 1.73 m2 (normal or mildly decreased). After the sleep study, clinical follow-up was performed through phone calls and medical records revisions at 1 month, 6 months, and then annually, searching for the occurrence of fatal and non-fatal cardiovascular events in a systematized way. Results: A total of 262 patients (64.1% males, mean age: 63±10 years and body mass index [BMI] 27.8±4.4 kg/m2) were studied. The frequencies of OSA and SSD were 58.4% and 25.6%, respectively. Patients with OSA had lower eGFR compared to patients without OSA (62±26 vs. 74±20 mL/min/1.73m2, p < 0.001) and consequently a higher rate of CKD (42.1 vs. 26.6%, p=0.009). In contrast, eGFR was similar in patients with and without SSD (65±29 vs. 68±23 mL/min/1.73 m2, p=0.38) and a no significance frequency of CKD (44.8 vs. 32.5%, p=0.07). In the multivariate analysis, AOS, but not SSD, was independently associated with eGFR (-10.57 (-16.46 - -4.68), p < 0.001) and with CKD (OR = 1.95, 95% CI=1.12-3.38, p=0.01). The interactions of OSA and SSD with eGFR and the presence of CKD were not significant. These results remained unchanged after evaluating AHI and sleep duration as continuous variables or setting SSD as < 5 hours. In an exploratory analysis, after a median follow up of 25 months, forty-three cardiovascular events (15 episodes of acute myocardial infarction, 1 coronary artery bypass graft, 6 strokes, 7 deaths and 14 stent restenosis). Considering the combined events, we did not find significant differences between OSA and SSD groups and their counterparts so far. Conclusion: In patients with CAD, OSA, but not SSD was independently associated with lower GFR and CKD, markers of poor prognosis in these patients
770

一般帳戶投資型年金之資產負債管理:免疫理論與最適資產配置之應用

謝冠生 Unknown Date (has links)
本研究主要是針對投資型年金之資產負債管理作探討,其中是就規避利率風險對於資產負債管理上的影響以及分析資產配置最適化作為研究的架構,而所利用的研究方法乃是取決於建構利率隨機模型並輔以免疫理論與Markowitz投資組合理論,以期在規避利率風險的同時,亦能將資產配置達至最佳化。 首先,為實際模擬出符合現實經濟環境變動下的隨機利率期間模型,本研究利用C.I.R利率期間結構模型來建構年金保單期間的利率結構,並且由於投資型年金之保單價值的累積特性,因此本研究同時亦建構出連接保單價值的投資資產之報酬率型態,進而模擬出各期之現金流量以及各項投資資產的存續期間;再者,藉由Markowitz投資組合理論,以在免疫條件之限制下進行最適資產配置之評估。 最後,以某知名的保險公司所推出的投資型年金商品作為本研究之實證對象,透過模擬之方法,將研究模型中之各項參數予以評估,並且根據上述之研究過程將免疫理論與投資組合理論相連接,以檢視投資型年金商品在規避利率風險的狀態下,其最適之資產配置比例是否與現行法令之規範相牴觸,而能給予適時之建議。另外,由本實證結果可知,經由本研究的分析流程,可以有效地給予年金管理者規劃出年金資產負債管理時的最適投資組合比例,並且在增加外國投資資產時,更能有效的增加年金資產之報酬,同時也不影響保險法對於投資資產的比例與總金額之限制。再者,對於探討規避利率風險前後之資產組合之資產報酬之變化時,可以進一步了解到,當年金管理者在運用免疫策略來規避利率風險時,其所面對的風險成本之多寡,以作為制定避險決策時的依據。 / This research explores the asset-liability management (ALM) for the Investment-Link-Annuity. Two aspects investigated in this research are the interest rate risk and the optimal asset allocation. Moreover, the major issue investigated here is the trade-off between the optimal investment return and the hedge of interest rate risk. We refer this trade-off as ALM cost. By using stochastic interest rate model, Immunization theory and Portfolio Selection Model, we construct an ALM model to achieve the optimal asset allocation given on hedging the interest rate risk under the immunization strategies for the insurance company. First, we utilize the public trading data for investment market in Taiwan and in USA from 1985 to 2000 and the investment-link annuity product of a well-know insurance company in Taiwan to simulate the cash flow and demonstrate the implementation of our model. By analyzing different simulations under various scenarios, the empirical results are as the followings: 1.The ALM cost for immunization strategies is very small, and is estimated to be about 1% to 2%. Therefore, we suggest that insurance companies should start to undertake the asset liability management as soon as possible. 2.If relaxing the investment restrictions of Insurance Law or allowing insurance company to invest in foreign investment market, the overall investment return will be increased and the ALM cost will be reduced effectively.

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