A presente investigação aborda temas relacionados ao grupo Fluxus no acervo do MAC-USP. Fluxus foi um coletivo artístico que atuou nos limites da arte durante as décadas de 1960 e 1970, questionando valores instituídos pelos sistemas oficiais de produção, circulação e exibição de objetos artísticos. Tendo como referência as poéticas Fluxus, as importantes realizações que constituem a sua história, dados e fatos que situam as atividades de seus integrantes na história do surgimento das novas linguagens artísticas da segunda metade do séc. XX, realizamos um amplo levantamento sucedido de documentação e análise crítica de algumas dentre as 116 obras selecionadas no acervo do MAC-USP de autoria de artistas Fluxus. / The present study deals with themes related to the Fluxus group in the MAC-USP collection. Fluxus was an artistic group that worked in the boundaries of art during the Sixties and Seventies, having questioned the values established by the official systems of art production, circulation and exhibition. Regarding Fluxus poetics, the important accomplishments that form its history, data and facts which place the activities of its artists in the history of new languages outbreak during the second part of XX century, we carry out a wide survey followed by registry and critical analyze in some of the 116 works of Fluxus artists which were selected from the MAC-USP collection.

Esta pesquisa investiga a prática de artistas do Nordeste brasileiro a partir do uso do carimbo como linguagem, no intuito de compreender essas produções, sob o contexto sociocultural e político no qual estão inseridas. Apresentamos uma arqueologia do carimbo, aproximando-o da xilogravura a partir da técnica de impressão, para, em seguida, traçar um panorama mais geral de sua emergência na história da arte moderna e contemporânea. A partir da pesquisa no acervo do Museu de Arte Contemporânea da Universidade de São Paulo (MAC USP) propomos um levantamento que contempla uma tipologia dos carimbos bem como o contexto politico e social de seus usos. Em paralelo, uma pesquisa de campo foi desenvolvida no Triângulo Amoroso região compreendida nesta pesquisa pelas cidades de Natal, João Pessoa e Recife no intuito de investigar junto aos artistas suas produções no recorte temporal entre 1960 e 1980. Por fim, apresentamos as práticas dos artistas José Cláudio, Falves Silva, Jota Medeiros, Unhandeijara Lisboa, Daniel Santiago, Leonhard Frank Duch e Paulo Bruscky, com intuito de problematizar o uso do carimbo como dispositivo gráfico e político situado em uma produção que caminha à margem das instituições artísticas no Brasil. / This research investigates the use of the rubber stamp as a language in the practice of artists in Brazilian Northeast in order to understand these productions under the social, cultural and political context in which they work. We present an archeology of the rubber stamp, approaching it to the woodcut thought the printing technique and then, we draw up a more general overview of its emergence in the history of modern and contemporary art. Based on a research through the collection of the Museum of Contemporary Art of the University of São Paulo (MAC USP) a data raising is being proposed including a typology of rubber stamps regarding the political and social context of their use. In parallel a field research was conducted in the Love Triangle region delimited in this research through the cities Natal, João Pessoa and Recife in order to investigate with the artists about their productions in the time frame from 1960 to 1980. Finally, we present, the practices of the artists José Cláudio, Falves Silva, Jota Medeiros, Unhandeijara Lisboa, Daniel Santiago, Leonhard Frank Duch and Paulo Bruscky, aiming to discuss the use of the rubber stamp as a graphic and political device in an artistic production that works in the fringe of artistic institutions in Brazil.

A doação de obras do espólio de Yolanda Mohalyi apresenta-se como exercício para a compreensão do que representa a aquisição de coleções particulares para a constituição e a organização de um acervo especializado em arte contemporânea. O estudo sobre a incorporação do espólio de Yolanda Mohalyi pode contribuir para uma melhor compreensão sobre o perfil do acervo MAC USP e, principalmente, indicar a importância dos parâmetros adotados nos processos de doação e aquisição de obras de arte em acervos públicos. Através da análise da trajetória de Yolanda Mohalyi e de sua coleção doada ao MAC USP, em 1979 se torna possível identificar questões que envolvem os mecanismos de incorporação de obras, de manutenção das obras e de pesquisa das mesmas, assim como a definição do que se constitui um acervo e uma coleção. / The donation of Yolanda Mohalyi\'s legacy shows itself as an exercise for the comprehension of the meaning of the acquisition of private collections to the constitution and organization of a collection specialized in contemporary art. The study of the incorporation of Yolanda Mohalyi\'s legacy can contribute for a better comprehension of the MAC USP collection\'s profile and, above all, indicates the importance of the criteria adopted on the donation and acquisition of works of art in public collections. By analyzing the history of Yolanda Mohalyi and the history of her collection donated to MAC USP in 1979, it is possible to identify issues that involve the mechanisms of incorporation of works of art, their conservation and the research about them, as well as the way a Collection is constituted.

Esta pesquisa de mestrado teve por objetivo o estudo das obras em acervo no Museu de Arte Contemporânea da Universidade de São Paulo de autoria dos artistas do Gruppo degli Otto, adquiridas por Francisco Matarazzo Sobrinho, em 1952 e 1954, na XXVI e na XXVII Bienal de Veneza, para o acervo do antigo Museu de Arte Moderna de São Paulo. As obras permitem, um estudo sobre os artistas e a formação do Gruppo degli Otto, além de uma imersão na produção de Lionello Venturi (Modena, 1885 Roma, 1961), crítico e historiador da arte que se coloca a frente desses artistas. Levaram também a uma pesquisa a respeito do cenário artístico daquele momento, tanto da Itália, de onde as obras partem, quanto do Brasil, para onde as obras se destinam, e à construção de uma história a respeito da crítica de arte italiana no ambiente da Bienal de Veneza na Guerra Fria, além do estudo do papel da instituição veneziana na fundação da Bienal de São Paulo e os impactos e ramificações deste debate crítico no Brasil. / This master\'s research intended to study the works in the collection not Museum of Contemporary Art, University of São Paulo by the artists of the Gruppo degli Otto, that were acquired by Francisco Matarazzo Sobrinho, in 1952 and 1954, at the XXVI and XXVII Venice Biennale, to integrate the collection of the former Museum of Modern Art of São Paulo. Those paintings led to a study on the artists that composed the Gruppo degli Otto and its foundation. They also allowed an immersion in the production of Lionello Venturi (Modena, 1885 - Rome, 1961), critic and art historian, who took to himself the role of the critic ahead of the group. The works also lead to a research on the artistic scene of that moment, both in Italy, where the paintings are made, as well as in Brazil, the place to where those paintings would be destined to live, as well as the study of the history of Italian art criticism in the environment the Venice Biennale in the Cold War, and lastly the study of the role of the Venetian institution in the founding of the São Paulo Bienal and the impacts and changes of this critical debate in Brazil.

Le schéma Marker-And-Cell (MAC) est un schéma de discrétisation des équations aux dérivées partielles sur maillages cartésiens, très connu en mécanique des fluides. Nous nous intéressons ici à son analyse mathématique dans le cadre des écoulements incompressibles sur des maillages cartésiens non-uniformes en dimension 2 ou 3. Dans un premier temps nous discrétisons les équations de Navier-Stokes pour un écoulement incompressible stationnaire; nous établissons des estimations a priori sur les suites de vitesses et pressions approchées qui permettent d’une part d'établir l’existence d’une solution au schéma, et d’obtenir la compacité de ces suites lorsque le pas d’espace tend vers 0. Nous montrons alors la convergence de ces suites (à une sous-suite près) vers une solution faible du problème continu, ce qui nécessite une analyse fine du terme de convection non linéaire. Nous nous intéressons ensuite aux équations de Navier-Stokes en régime instationnaire avec une discrétisation en temps implicite. Nous démontrons que le schéma préserve les propriétés de stabilité du problème continu et obtenons ainsi l’existence d’une solution au schéma. Puis, grâce à des techniques de compacité et en passant à la limite dans le schéma, nous démontrons qu’une suite de vitesses approchées converge. Si l’on se restreint au problème de Stokes, et en supposant de plus que la condition initiale de la vitesse est dans H 1 , nous obtenons une estimation sur la pression qui permet de montrer la convergence forte des pressions approchées. Enfin nous étendons l’analyse aux écoulements incompressibles à masse volumique variable. On montre la convergence du schéma. / The Marker-And-Cell (MAC) scheme is a discretization scheme for partial derivative equations on Cartesian meshes, which is very well known in fluid mechanics. Here we are concerned with its mathematical analysis in the case of incompressible flows on two or three dimensional non-uniform Cartesian grids. We first discretize the steady-state incompressible Navier-Stokes equations. We show somea priori estimates that allow to show the existence of a solution to the scheme and some compactness and consistency results. By a passage to the limit on the scheme, we show that the approximate solutions obtained with the MAC scheme converge (up to a subsequence) to a weak solution of the Navier-Stokes equations, thanks to a careful analysis of the nonlinear convection term. Then, we analyze the convergence of the unsteady-case Navier-Stokes equations. The algorithm is implicit in time. We first show that the scheme preserves the stability properties of the continuous problem, which yields, the existence of a solution. Then, invoking compactness arguments and passing to the limit in the scheme, we prove that any sequence of solutions (obtained with a sequence of discretizations the space and time step of which tend to zero) converges up to the extraction of a subsequence to a weak solution of the continuous problem. If we restrict ourselves to the Stokes equations and assume that the initial velocity belongs to H 1, then we obtain estimates on the pressure and prove the convergence of the sequences of approximate pressures. Finally, we extend the analysis of the scheme to incompressible variable density flows. we show the convergence of the scheme.

Ce mémoire de thèse se place dans le contexte des applications de surveillance de l’environnement nécessitant des mesures régulières de caractéristiques biologiques ou géo-physiques. Il s’agit par exemple de mesurer la propagation de polluants dans les cours d’eau, de surveiller le développement de bactérie dans des eaux de baignade. Les réseaux de capteurs sans fils (RCsF) apparaissent comme des solutions économiques et fiables pour permettre l’automatisation de la collecte de telles données. Le bon fonctionnement de ces réseaux dépend de la qualité des transmissions radio, ce qui est particulièrement vrai dans des milieux où les conditions sont peu favorables à la propagation des ondes radio et où les liens peuvent donc se révéler intermittents. L’objectif de ce travail est de proposer une solution protocolaire efficace dans de telles conditions, dans le cas particulier d’un réseau de capteur déployé à la surface de l’eau. Le mémoire débute par la description d’une méthodologie, des mécanismes et d’une plate-forme destinée à explorer la qualité d’un lien radio situé à la surface de l’eau. Nous présentons différentes mesures qui ont été effectuées. Les solutions protocolaires que nous proposons prennent en compte le caractère évolutif de la topologie due à l’instabilité des liens radio afin d’améliorer l’efficacité de la collecte et de réduire la consommation énergétique des noeuds. Notre approche est basée sur la reconstruction périodique de la topologie, la communication entre les noeuds par rendez-vous définis par des fenêtres de transmissions, l’utilisation du multi-canal pour drainer les données et l’adaptation de la taille des fenêtres de transmission en fonction du trafic local. L’ensemble de ces propositions est validé par prototypage et par simulation sur NS-3. Les résultats montrent que notre solution est capable de collecter les données dans une topologie dynamique tout en réduisant à la fois le délai de collecte et la consommation énergétique. / This thesis takes place in the context of environmental monitoring applications requiring regular measurements of biological or geophysical characteristics. These applications include for instance the measuring of the spread of pollutants in rivers, monitoring of the development of bacteria in bathing waters, etc. Wireless Sensor Networks (WSNs) provide cost-effective and reliable solutions to allow the automation of such data gathering. The good functioning of these networks depends on the quality of the radio transmissions, which is particularly true in environments where the conditions are not suitable for the propagation of radio waves and where the links may therefore be intermittent. The objective of this work is to propose an effective protocol solution under such conditions, in the particular case of a sensor network deployed on the water surface. The thesis begins with a description of the methodology, mechanisms and a platform for exploring the quality of a radio link displayed at the water surface. We present different measures that have been carried out. The protocol solutions we propose take into account the evolutionary nature of the topology due to the instability of the radio links in order to improve the efficiency of the data gathering and to reduce the energy consumption of the nodes. Our approach is based on the periodic reconstruction of the topology, the communication between nodes by appointments defined by transmission windows, the use of the multi-channel to drain the data and the adaptation of the transmission window size as a function of local traffic. All these propositions are validated by prototyping and simulation using NS-3. The results show that our solution is capable of collecting data in a dynamic topology while reducing both gathering time and energy consumption.

La méthode IIM (Immersed Interface Method) permet d'étendre certaines méthodes numériques à des problèmes présentant des discontinuités. Elle est utilisée ici pour étudier un fluide incompressible régi par les équations de Navier-Stokes, dans lequel est immergée une membrane exerçant une force singulière. Nous utilisons une méthode de projection dans une grille de différences finies de type MAC. Une dérivation très complète des conditions de saut dans le cas où la viscosité est continue est présentée en annexe. Deux exemples numériques sont présentés : l'un sans membrane, et l'un où la membrane est immobile. Le cas général d'une membrane mobile est aussi étudié en profondeur. / The Immersed Interface Method allows us to extend the scope of some numerical methods to discontinuous problems. Here we use it in the case of an incompressible fluid governed by the Navier-Stokes equations, in which a membrane is immersed, inducing a singular force. We use a projection method and staggered (MAC-type) finite difference approximations. A very complete derivation for the jump conditions is presented in the Appendix, for the case where the viscosity is continuous. Two numerical examples are shown : one without a membrane, and the other where the membrane is motionless. The general case of a moving membrane is also thoroughly studied.

Architecture et mécanismes de bout en bout pour les communications mobiles et sans fil dans l'Internet. La gestion performante de la mobilité et l'amélioration des performances des couches basses sont deux enjeux fondamentaux dans le contexte des réseaux sans fil. Cette thèse apporte des solutions originales et innovantes qui visent à répondre à ces deux problématiques empêchant à ce jour d'offrir des possibilités de communication performantes et sans couture aux usagers mobiles accédant à l'Internet via des réseaux d'accès locaux sans fil (WLAN). Ces solutions se distinguent en particulier par l'impact minimum qu'elles ont sur les protocoles standards de l'Internet (niveaux transport et réseau) ou de l'IEEE (niveaux physique et liaison de données). S'inscrivant dans les paradigmes de "bout en bout" et "cross-layer", notre architecture permet d'offrir des solutions efficaces pour la gestion de la mobilité : gestion de la localisation et des handover en particulier. En outre, nous montrons que notre approche permet également d'améliorer l'efficacité des transmissions ainsi que de résoudre efficacement plusieurs syndromes identifiés au sein de 802.11 tels que les anomalies de performance, l'iniquité entre les flux et l'absence de contrôle de débit entre la couche MAC et les couches supérieures. Cette thèse résout ces problèmes en combinant des modèles analytiques, des simulations et de réelles expérimentations. Ces mécanismes adaptatifs ont été développés et intégrés dans une architecture de communication qui fournit des services de communication à haute performance pour réseaux sans fils tels que WIFI et WIMAX. / Wireless networks, because of the potential pervasive and mobile communication services they offer, are becoming the dominant Internet access networks. However, the legacy Internet protocols, still dominant at that time, have not been designed with mobility and wireless in mind. Therefore, numerous maladjustments and “defaults of impedance” can be observed when combining wireless physical and MAC layers with the traditional upper layers. This thesis proposes several solutions for a pacific coexistence between these communication layers that have been defined and designed independently. Reliable mobility management and Low layer performance enhancements are two main challenging issues in the context of wireless networks. Mobility management (which is mostly based on mobile IP architecture nowadays) aims to continuously assign and control the wireless connections of mobile nodes amongst a space of wireless access networks. Low layer performance enhancements mainly focus on the transmission efficiency such as higher rate, lower loss, interference avoidance. This thesis addresses these two important issues from an original and innovative approach that, conversely to the traditional contributions, entails a minimum impact on the legacy protocols and internet infrastructure. Following the “end to end” and “cross layer” paradigms, we address and offer efficient and light solutions to fast handover, location management and continuous connection support through a space of wireless networks. Moreover, we show that such an approach makes it possible to enhance transmission efficiency and solve efficiently several syndromes that plague the performances of current wireless networks such as performance anomaly, unfairness issues and maladjustment between MAC layer and upper layers. This thesis tackles these issues by combining analytical models, simulations and real experiments. The resulting mechanisms have been developed and integrated into adaptive mobility management communication architecture that delivers high performing communication services to mobile wireless systems, with a focus on WIFI and WIMAX access networks.

Malgré leur réussite remarquable, les premières versions des normes de réseaux locaux sans fil IEEE 802.11, IEEE 802. 11 a/b/g WLAN, sont caractérisées par une efficacité spectrale faible qui est devenue insuffisante pour satisfaire la croissance explosive de la demande de capacité et de couverture. Grâce aux progrès considérables dans le domaine des communications sans fil et l'utilisation de la bande de fréquence autour de 5 gigahertz le standard IEEE 802.11n et plus récemment 1'IEEE 802.11ac ont amélioré les débits offerts par la couche physique. Cela été possible grâce principalement à l'introduction des techniques multi-antennaires (MIMO, pour Multiple-Input) et des techniques avancées de modulation et de codage. Aujourd'hui, deux décennies après sa première apparition, le Wi-Fi est présenté comme une technologie WLAN permettant des débits supérieurs à 1 gigabit par seconde. Cependant, dans la plupart des scénarios de déploiement du monde réel, il n'est pas possible d'atteindre la pleine capacité offerte par la couche physique. Avec la croissance rapide de la densité des déploiements des WLANs et l'énorme popularité des équipements Wi-Fi, la réutilisation spatiale doit être optimisée. D'autre part, des nouveaux cas d’utilisation sont prévus pour décharger les réseaux cellulaires et pour couvrir des grandes surfaces (stades, gares, etc.). Ces environnements de haute densité représentent un vrai défi pour les générations actuelles de Wi-Fi qui doivent offrir une meilleure qualité à moindre coût. C'est dans ce contexte que s’inscrit l'objectif de cette thèse qui porte sur l'amélioration de l'efficacité des protocoles de la couche MAC des réseaux WLAN de haute densité. Notamment, un des buts de cette thèse est de contribuer à la préparation de la prochaine génération du standard Wi-Fi : IEEE 802.11ax High Efficiency WLAN (HEW). Plutôt que de continuer à cibler l'augmentation des débits maximums théoriques, nous nous concentrons dans le contexte de HEW sur l'amélioration du débit réel des utilisateurs. Pour cela, on prend en compte tous les autres équipements associés à des WLANs voisins, qui essayent d'accéder au même canal de transmission d’une manière simultanée. Pour améliorer la performance du Wi-Fi dans ces environnements denses, nous proposons une adaptation dynamique du mécanisme de détection de signal. Comparé au contrôle de la puissance de transmission, le mécanisme proposé est plus incitatif parce que l'utilisateur concerné bénéficie directement de son application. Les résultats de nos simulations montrent des gains importants en termes de débit atteint dans les scénarios de haute densité. Ensuite, nous étudions l’impact de la nouvelle adaptation sur les mécanismes de sélection de débit actuellement utilisés. D'après les résultats obtenus, 1'adaptation proposée peut être appliquée sans avoir besoin de modifications substantielles des algorithmes de sélection de débit. Pour améliorer l'équité entre les différents utilisateurs, nous élaborons une nouvelle approche distribuée pour adapter conjointement le mécanisme de détection de signal et le contrôle de la puissance de transmission. Cette approche est évaluée ensuite dans différents scénarios de simulation de haute densité où elle prouve sa capacité à résoudre les problèmes d'équité en particulier en présence de nœuds d'anciennes générations dans le réseau, cela tout en améliorant le débit moyen d'un facteur 4 par rapport à la performance conventionnelle du standard. Enfin, nous concevons et mettons en œuvre une solution centralisée basée sur l'apprentissage à base de réseaux de neurones. Cette approche repose sur l'adaptation conjointe de puissance de transmission et du mécanisme de détection du signal. [...] / Despite their remarkable success, the first widely spread versions of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 Wireless Local Area Network (WLAN) standard, IEEE 802. 11 a/b/g, featured low spectral efficiencies that are becoming insufficient to satisfy the explosive growth in capacity and coverage demands. Thanks to the advances in the communication theory and the use of the 5 GHz frequency band, the IEEE 802.11n and recently the IEEE 802.1lac amendments improved the Physical Layer (PHY) data rates by introducing Multiple-Input Multiple Output (MIMO) techniques, higher Modulation and Coding Scheme (MCS), etc. Today, after almost two decades of its first appearance, Wi-Fi is presented as a gigabit wireless technology. However, the full potential of the latest PHY layer advances cannot be enabled in all real world deployment scenarios. With the rapidly increasing density of WLAN deployments and the huge popularity of Wi-Fi enabled devices, spatial reuse must be optimized. On another hand, the new challenging use case environments and the integration of mobile networks mainly for cellular offloading are limiting the opportunity of the current Wi-Fi generations to provide better quality at lower cost.In this thesis, we contribute to the current standardization efforts aiming to leverage the Wi-Fi efficiency in high density environments. At the time of writing this document, the IEEE 802.11ax Task Group (TG) is developing the specification for the High Efficiency WLAN (HEW) standard (next Wi-Fi evolution). Rather than continuing to target increased theoretical peak throughputs, we focus in the context of HEW on improving the throughput experienced by users in real life conditions where many other devices, belonging to neighboring overlapping networks, simultaneously contend to gain access. To enhance this performance, we propose a dynamic adaptation of the carrier sensing mechanism. Compare to controlling the transmission power, the proposed mechanism has more incentives because it benefits directly the concerned user. Extensive simulation results show impor1ant throughput gains in dense scenarios. Then, we study the impact of the new adaptation on the current rate control algorithms. We find that our adaptation mechanism operates efficiently without substantially modifying these algorithms that are widely used in today's operating WLANs. Furthermore, after analyzing the fairness performance of the proposed adaptation, we devise a new approach to jointly adapt the carrier sensing and the transmission power in order to preserve higher fairness degrees while improving the spatial reuse. This approach is evaluated in different dense deployment scenarios where it proves its capability to resolve the unfairness issues especially in the presence of legacy nodes in the network, while improving the achieved throughput by 4 times compared to the standard performance. Finally, we design and implement centralized learning-based solution that uses also an approach based on joint adaptation of transmission power and carrier sensing. This new solution takes benefit from the capability of artificial neural networks to model complex nonlinear functions to optimize the spatial reuse in dense WLANs while preserving fairness among contending nodes. The different contributions of this work have helped bring efficient solutions for future WiFi networks. We have presented these solutions to the IEEE 802.11ax TG where they were identified as important potential technical improvements for the next WLAN standard.

This diploma thesis deals with the design and implementation of an application suitable for the anonymization of PCAP files. The thesis presents TCP/IP model and for each layer highlights attributes that can be used to identify real people or organizations. Some of the anonymization methods suitable to modify highlighted attributes and sensitive data are described. The implemented application uses TShark tool to parse byte data of PCAP format to JSON format that is used in the application. TShark supports lots of network protocols which allows the application to anonymize various attributes.  Anonymization process is controlled by anonymization politics that can be customized by adding new attributes or anonymization methods.