Dans un monde où les réseaux deviennent une forme dominante d’organisation, la structure des réseaux et la position des individus en leur sein affectent les comportements individuels et les résultats économiques agrégés. L’analyse de la formation des réseaux par un planificateur central ou par les individus est au cœur de cette thèse en économie des réseaux. Le Chapitre 1 étudie de manière théorique la formation et la protection optimale des réseaux par un planificateur central sachant qu’un agent externe peut détruire k liens. La protection s’effectue soit en densifiant les liens entre les nœuds, soit en protégeant les liens. Lorsque le coût de protection est suffisamment faible, un réseau minimalement connecté constitué de liens protégés garantit le flux de communication; si ce coût est élevé, la solution optimale est de former un réseau symétrique où chaque nœud possède au moins k+1 liens non-protégés. Le Chapitre 2 explore la formation décentralisée de réseaux en laboratoire en analysant les décisions individuelles de formation de liens lorsqu’un agent a une valeur supérieure aux autres et que le processus de formation de liens est séquentiel. Les résultats montrent que la séquentialité facilite la coordination sur des réseaux efficaces mais qui ne correspondent pas à l’équilibre parfait en sous-jeu. L’hétérogénéité entre les agents accroit l’asymétrie du réseau en raison de la polarisation des liens sur l’agent à valeur supérieure. Le Chapitre 3 étudie l’impact de la formation endogène d’un réseau sur l’importance des effets de pairs, avec une application aux comportements malhonnêtes. Afin d’identifier les effets des comparaisons sociales, deux environnements contrôlés sont créés en laboratoire dans lesquels les individus choisissent ou non leurs pairs, puis observent leur comportement. Les résultats montrent que les effets de pairs sur les comportements malhonnêtes sont significativement accrus lorsque les individus peuvent choisir leurs pairs. / In a world where networks become a dominant form of organization, the structure of networks and the position of individuals in these networks affect individual behavior and aggregate economic outcomes. The analysis of network formation by a central planner or by individuals themselves is at the heart of this thesis on the economics of networks.Chapter 1 theoretically studies the optimal formation and protection of networks by a central planner knowing that an external agent can destroy k links. The protection of the network can be guaranteed either by densifying the links between nodes, or by protecting the links. When the cost of protection is relatively small, a minimally connected network composed of protected links guarantees the communication flow; if this cost is high, the optimal solution is to form a symmetric network where each node has at least k+1 non-protected links.Chapter 2 explores the decentralized formation of networks in the laboratory by analyzing individual linking formation decisions when one agent has a higher value than others and that the linking formation process is sequential. The results show that sequentiality facilitatesthe coordination on efficient networks but that do not correspond to the Subgame PerfectEquilibrium. The heterogeneity across agents increases the asymmetry of networks because of the polarization of links on the agent with a higher value.Chapter 3 studies the impact of the endogenous formation of networks on the importance of peer effects, applied to dishonest behavior. In order to identify the effects of social comparisons, two controlled environments are designed in the laboratory in which individuals choose or not their peers, and then observe their behavior. The results show that peer effects on dishonest behavior are significantly higher when individuals can choose their peers.

This diploma thesis describes several selected network attacks detection method using statistical models with NetFlow data. First are described several well known and threats for computer networks, which are easily detectable in the NetFlow data. Thesis also introduce and present the NetFlow technology including its protocol and architecture. The theoretical part of the thesis describes statistical methods with focus on the ASTUTE method, that can be used for an anomaly detection. Following part introduces tools used for method implementation as the NfSen plugins. Last parts of the thesis describe in detail implementation of the plugins and following plugins testing which included simulated network attacks.

La virtualisation de réseau permet de créer des réseaux logiques, dits virtuels sur un réseau physique partagé dit substrat. Pour ce faire, le problème d’allocation des ressources aux réseaux virtuels doit être résolu efficacement. Appelé VNE (Virtual Network Embedding), ce problème consiste à faire correspondre à chaque nœud virtuel un nœud substrat d’un côté, et de l’autre, à tout lien virtuel un ou plusieurs chemins substrat, de manière à optimiser un objectif tout en satisfaisant un ensemble de contraintes. Les ressources de calcul des nœuds et les ressources de bande passante des liens sont souvent optimisées dans un seul réseau substrat. Dans le contexte multi-domaine où la connaissance de l’information de routage est incomplète, l’optimisation des ressources de nœuds et de liens est difficile et souvent impossible à atteindre. Par ailleurs, pour assurer la continuité de service même après une panne, le VNE doit être réalisé de manière à faire face aux pannes. Dans cette thèse, nous étudions le problème d’allocation de ressources (VNE) sous diverses exigences. Pour offrir la virtualisation dans le contexte de réseau substrat multi-domaines, nous proposons une méthode de mappage conjoint des liens inter-domaines et intra-domaines. Avec une information réduite et limitées annoncées par les domaines, notre méthode est capable de mapper simultanément les liens intra-domaines et les liens inter-domaines afin d’optimiser les ressources. De plus, pour améliorer la robustesse des réseaux virtuels, nous proposons un algorithme d’évitement des pannes qui minimise la probabilité de panne des réseaux virtuels. Des solutions exactes et heuristiques sont proposées et détaillées pour des liens à bande passante infinie ou limitée. En outre, nous combinons l’algorithme d’évitement des pannes avec la protection pour proposer un VNE robuste et résistant aux pannes. Avec cette nouvelle approche, les liens protégeables puis les liens les moins vulnérables sont prioritairement sélectionnés pour le mappage des liens. Pour déterminer les liens protégeables, nous proposons une heuristique qui utilise l’algorithme du maxflow afin de vérifier etdedéterminerlesliensprotégeablesàl’étapedumappagedesliensprimaires. Encasd’insuffisance de ressources pour protéger tous les liens primaires, notre approche sélectionne les liens réduisant la probabilité de panne. / Network virtualization allows to create logical or virtual networks on top of a shared physical or substrate network. The resource allocation problem is an important issue in network virtualization. It corresponds to a well known problem called virtual network embedding (VNE). VNE consists in mapping each virtual node to one substrate node and each virtual link to one or several substrate paths in a way that the objective is optimized and the constraints verified. The objective often corresponds to the optimization of the node computational resources and link bandwidth whereas the constraints generally include geographic location of nodes, CPU, bandwidth, etc. In the multi-domain context where the knowledge of routing information is incomplete, the optimization of node and link resources are difficult and often impossible to achieve. Moreover, to ensure service continuity even upon failure, VNE should cope with failures by selecting the best and resilient mappings. Inthisthesis,westudytheVNEresourceallocationproblemunderdifferentrequirements. To embed a virtual network on multi-domain substrate network, we propose a joint peering and intra domain link mapping method. With reduced and limited information disclosed by the domains, our downsizing algorithm maps the intra domain and peering links in the same stage so that the resource utilization is optimized. To enhance the reliability of virtual networks, we propose a failure avoidance approach that minimizes the failure probability of virtual networks. Exact and heuristic solutions are proposed and detailed for the infinite and limited bandwidth link models. Moreover, we combine the failure avoidance with the failure protection in our novel protection-level-aware survivable VNE in order to improve the reliability. With this last approach, the protectable then the less vulnerable links are first selected for link mapping. To determine the protectable links, we propose a maxflow based heuristic that checks for the existence of backup paths during the primary mapping stage. In case of insufficient backup resources, the failure probability is reduced.

Liberalized electricity markets, increased awareness of clean energy resources and theirdecreasing costs have resulted in large numbers of distributed power generators beinginstalled on distribution network. Installation of distributed generation has altered thepassive nature of distribution grid. A concept of Active Distribution Network is proposedwhich will enable present day infrastructure to host renewable energy resources reliably.Fault management that includes fault localization, isolation and service restoration ispart of active management of distribution networks.This thesis aims to introduce a distributed protection methodology for fault localizationand isolation. The objective is to enhance reliability of the network. Faults are identifiedbased on root mean square values of current measurements and by comparing thesevalues with preset thresholds. The method based on multi-agent concept can be usedto locate the faulty section of a distribution network and for selection of faulty phases.The nodal Bus Agent controls breakers that are associated with it. Based on indicationof fault, adjacent bus Agents communicate with each other to identify location of fault.A trip signal is then issued to corresponding Breakers in adjacent Bus Agents, isolatingthe faulty section of line. A case study was carried out to verify suitability of the proposedmethod. A meshed network model and multi-agent based protection scheme wassimulated in Simulink SimPowerSystems. Considering nature of Distribution Network,separate breakers for each phase are considered. The distribution network protectionsystem identified fault introduced in the network correctly along with interrupting thefault current.Keywords

The ever increasing demands of Internet users caused by the introduction of new high bandwidth applications and online services as well as the growing number of users and devices connected to the Internet, bring many challenges for the operators, especially in the last mile section of the network. Next generation access architectures are expected to offer high sustainable bandwidth per user. They also need to support a much larger service areas to decrease number of current central offices and hence potentially save the network expenditures in the future. Obviously, it requires high capacity and low loss transmission and optical fiber technology is the only future proof candidates for broadband access. Although this technology has already been widely deployed in the core networks, it is hard to use the same expensive devices made for core segment to solve the last mile bottlenecks, due to the low number of users sharing the network resources (and deployment cost). Therefore, the next generation optical access (NGOA) networks need to be designed with consideration of cost efficiency in the first place.   Network reliability is also turning to be an important aspect for the NGOA networks as a consequence of long reach, high client count and new services requiring uninterrupted access. Consequently, new architectures not only need to be cost efficient but also they should fulfill the increasing reliability requirements.   Although several NGOA alternatives have been proposed in the literatures, there is not yet an agreement on a single architecture. As described earlier, network expenditure and reliability performance are the two main factors to be considered. Therefore, this thesis concentrates on finding a suitable alternative for future broadband access by evaluating the reliability performance and total cost of ownership for several NGOA candidates. In particular, in this thesis we analyze the tradeoff between the cost needed to deploy backup resources and the reliability performance improvement obtained by the provided survivability mechanism.   First, we identified the suitable NGOA candidates by comparing two main groups of optical access networks, namely passive optical networks (PONs) and active optical networks (AONs), in terms of cost, reliability performance and power consumption. The initial results have shown that wavelength division multiplexing PON (WDM PON) is the most promising alternative for the NGOA networks because of its high potential capacity, low cost and power consumption. So we continued our studies by investigating two WDM-based PON architectures regarding their cost and reliability performance. The study has also included a proposed fiber layout compatible with these two candidates aiming to minimize the required investment needed to offer protection. Our primary results confirmed that hybrid PON (HPON) is the best alternative for the NGOA networks. Therefore we further analyzed this candidate considering several variants of HPON. The most important components and sections of the HPON, which need to be protected to decrease the impact of each failure in the network have been identified. Based on these outcomes, two resilience architectures protecting the shared part of the HPON were proposed and their reliability performance parameters as well as cost of protection were evaluated. According to the results, using our proposed protection schemes a considerable improvement in reliability performance of the HPON variants can be provided at minor extra investment. We also introduced a cost efficient HPON architecture with different levels of protection for users with various reliability requirements, i.e. the protection of shared parts of the access network for all the connected users and end-to-end resilience scheme for some selected ones (e.g., business users). To gain an overall view on the cost efficiency of the proposed architecture, we evaluated the investment required for deploying these schemes considering several network upgrading paths towards a protected network. Moreover, a sensitivity analysis investigating the influence of network deployments time and the density of the users with higher availability requirements was presented.   In summary, we have shown that HPON is able to fulfill the main NGOA requirements such as high bandwidth per-user, large coverage and client count. The work carried out in the thesis has proved that HPON can also offer high reliability performance while keeping the network expenditures at an acceptable level. Moreover, low power consumption and high flexibility in resource allocation of this architecture, makes it a winning candidate for the NGOA networks. Therefore, HPON is a promising architecture to be deployed as NGOA network in the near future considering the fact that components are soon to be available in the market. / <p>QC 20130530</p> / FP7 EU project, Optical Access Seamless Evolution(OASE)

Made available in DSpace on 2016-04-28T20:38:05Z (GMT). No. of bitstreams: 1 Paula Orchiucci Miura.pdf: 1310094 bytes, checksum: cc7fb098b82684cb54f582c02421a2c3 (MD5) Previous issue date: 2012-04-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The violence inside family, theme of this work, doesn t refers only to excess of physical, sexual, verbal strength against others, but also to the absence of an investment on care, on preoccupation with others that needs emotional and physical care. The violence inside family affects, marks, causes failures on the process of personal maturation, according Winnicott (1962/1990a), it s not possible the health development of a child on environments that aren t sufficiently good . Winnicott doesn t uses the term violence inside family properly said, but substantiating this term in his theory violence inside family would be the absence of an environment sufficiently good , where this kind of environment has self established as a pattern on development process, precluding the healthy development of the members of this family. This research had as objectives: rescue and compare historical, legislative, populational, political, cultural and social aspects of the violence inside families on Brazil and Portugal; and comparatively investigate and analyze the intervention process adopted by services of Arujá/Brazil and Coimbra/Portugal on the treatment on the cases of people who have experienced situations of violence inside family and, concomitantly, analyze the psychic constitution of those people based on Winnicott s theory. This work was realized by means of participating observation on the following services: Receive Program and Childs and Teenagers Courtyard Center as well as the observation of articulation of those services with other services that composes the Arujá Protection Network. At Coimbra, the participation observation occurred at Inside Family Violence Service and on Childs and Teenagers Protection Committee, besides of the observation of the articulation of those with other services of Coimbra s Protection Network. Other strategy adopted for the realization of this research was the case studies. With this study it was possible to realize that was progress on investigations, on legislations and on social politics against inside family violence in Portugal and in Brazil, but also it was realized that the perpetuation of this kind of violence occurs considerately until nowadays. In relation to therapeutic action of Coimbra s and Arujá s Protection Network, it was realized that the effectiveness of the first Network, the responsibles for this was meeting themselves to discuss and talk the best action to each occurrence. Differently of the second, that has presented numerous failures of communication and articulation. By the other way, some specific services of Aruja s Protection Network Receive Program, Courtyard Center and Shelter were able to develop an intervention work, based on Winnicott s theory, that would be sufficiently good on the process of maintenance of being of child, teenagers and their families that have experienced situations of violence inside family. The Coimbra s Network Protection, on ambit of therapeutic intervention presented some failures on center itself mostly on the eradication of the inside of family violence, neglecting the patient by a few. It concludes that therapeutic actions of services should focus on the maturation of the being and not only on a symptom showed by him on a determinate moment of his life. Act on ethical manner and therapeutically is much more than eliminate momentarily the violence inside the family socially defined; providing sufficiently good conditions for the people who have their maturation process interrupted they could continue on being . Without this kind of intervention, the inside of family violence cycle would never halt / A violência intrafamiliar, tema desse trabalho, não se refere apenas ao excesso de força física, sexual, verbal contra o outro, mas também à ausência de um investimento no cuidado, na preocupação com o outro que necessita de acolhimento emocional e cuidados físicos. A violência intrafamiliar afeta, marca, provoca falhas no processo de amadurecimento pessoal, segundo Winnicott (1962/1990a), não é possível o desenvolvimento saudável de crianças em ambientes que não sejam suficientemente bons . Winnicott não utiliza o termo violência intrafamiliar propriamente dito, mas fundamentando este termo em sua teoria, violência intrafamiliar seria a ausência de um ambiente suficientemente bom , onde este tipo de ambiente se estabeleceu como um padrão no processo do desenvolvimento, impossibilitando o desenvolvimento saudável dos membros dessa família. Esta pesquisa teve como objetivos: resgatar e comparar aspectos histórico, legislativo, populacional, político, cultural e social da violência intrafamiliar no Brasil e em Portugal; e investigar e analisar comparativamente o processo de intervenção adotado pelos serviços de Arujá/Brasil e Coimbra/Portugal no atendimento dos casos de pessoas que vivenciaram situações de violência intrafamiliar e, concomitamente, analisar o processo de constituição psíquica dessas pessoas com base na teoria winnicottiana. Esse trabalho foi realizado por meio da observação participante nos seguintes serviços: Programa Acolher e Centro de Convivência da Criança e do Adolescente, bem como da observação da articulação desses serviços com outros serviços que compõem a Rede de Proteção de Arujá. Em Coimbra, a observação participante aconteceu no Serviço de Violência Intrafamiliar e na Comissão de Proteção de Crianças e Jovens, além de observar a articulação desses com outros serviços da Rede de Proteção de Coimbra. Outra estratégia adotada para a realização dessa pesquisa foi o estudo de casos. Com esse estudo pôde-se perceber que houve progressos nas investigações, nas legislações e nas políticas sociais contra a violência intrafamiliar tanto em Portugal quanto no Brasil, mas também se percebeu que a perpetuação deste tipo de violência se arrasta consideravelmente até hoje. Com relação à ação terapêutica das Redes de Proteção de Coimbra e de Arujá, pôde-se perceber a atuação eficaz da primeira Rede, os responsáveis por esta estavam sempre se reunindo para conversar e discutir a melhor ação para cada ocorrência. Diferentemente da segunda, que apresentou inúmeras falhas de comunicação e articulação. Por outro lado, alguns serviços específicos da Rede de Proteção de Arujá Programa Acolher, Centro de Convivência e Abrigo conseguiram desenvolver um trabalho de intervenção, baseada na teoria winnicottiana, que pudesse ser suficientemente bom no processo de continuidade-de-ser das crianças, adolescentes e suas famílias que experienciaram situação de violência intrafamiliar. Já a Rede de Proteção de Coimbra, no âmbito da intervenção terapêutica apresentou algumas falhas, ao centrar-se mais na eliminação da violência intrafamiliar, descurando-se um pouco do indivíduo. Conclui-se que a ação terapêutica dos serviços deve focar o processo de amadurecimento do indivíduo e não somente o sintoma apresentado por ele num determinado momento de sua vida. Atuar de maneira ética e terapêutica é muito mais do que eliminar momentaneamente a violência intrafamiliar definida sociologicamente; é proporcionar condições suficientemente boas para que as pessoas que tiveram seu processo de amadurecimento interrompido possam, então, continuar-a-ser. Sem esse tipo de intervenção o ciclo da violência intrafamiliar nunca cessará

Les travaux de cette thèse portent sur l'intégration dans le réseau électrique du limiteur supraconducteur de courant (SCFCL). Un modèle du ruban supraconducteur ont été développé et validé grâce à une comparaison avec des tests expérimentaux. Premièrement, ce modèle a permis le dimensionnement du SCFCL du projet Eoccoflow (projet européen). Dans un deuxième temps, le modèle de SCFCL est intégré dans différents types de réseau. D'une part, l'intégration du SCFCL dans les réseaux haute tension continu maillés rend vraisemblable la protection de tels réseaux. D'autre part, grâce au SCFCL de nouvelles architectures du réseau de distribution sont proposées permettant l'intégration massive de génération distribuée. Cette thèse se clot sur le dimensionnement et les tests d'un SCFCL pour un réseau à taille réduite. / This PhD deals with superconducting fault current limiter (SCFCL) network integration. A model of a superconducting tape had been developed and validated in comparison with experimental quench tests. This SCFCL model allowed us to design the SCFCL of the european project Eccoflow. Using this SCFCL model, SCFCLs are integrated in various types of networks. On one hand, SCFCL benefits are first studied in case of meshed HVDC networks. Indeed, the SCFCL makes realistic the protection of such networks. On the other hand, thanks to the SCFCL some new distribution network topologies are suggested in order to increase the distributed generation integration capacity. This PhD ends with the design and the test of a SCFCL in a downsize scale network.