Submitted by Davi Silistino de Souza (dvssouza@hotmail.com) on 2018-02-27T18:37:49Z No. of bitstreams: 1 Dissertação - Davi.pdf: 1308006 bytes, checksum: 3dbf8e602397954ecbcacf60eed1b2b6 (MD5) / Approved for entry into archive by Elza Mitiko Sato null (elzasato@ibilce.unesp.br) on 2018-02-28T14:52:18Z (GMT) No. of bitstreams: 1 souza_ds_me_sjrp.pdf: 1308006 bytes, checksum: 3dbf8e602397954ecbcacf60eed1b2b6 (MD5) / Made available in DSpace on 2018-02-28T14:52:18Z (GMT). No. of bitstreams: 1 souza_ds_me_sjrp.pdf: 1308006 bytes, checksum: 3dbf8e602397954ecbcacf60eed1b2b6 (MD5) Previous issue date: 2018-02-09 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de confiança e Aperfeiçoamento de financiamento desta Pessoal de Nível pesquisa Superior (CAPES) / As injustiças e opressões enfrentadas pelos subalternos vêm sido estudadas há algumas décadas pelos Grupos de Estudos Subalternos, seja o de origem indiana ou latina. Com o auxílio dessas pesquisas, na contemporaneidade, os indivíduos excluídos adquirem voz, sendo ouvidos e respeitados na sociedade. Considerando esses fatos, a dissertação tem como objetivo contribuir para esse enfrentamento, ao estudar de que maneira a subalternidade é representada nas personagens de Cloud Atlas (2004), romance escrito por David Mitchell. Em nossas análises, evidenciaremos a presença de uma crítica às estruturas hegemônicas na construção das protagonistas, pertencentes a sociedades organizadas em hierarquias sociais e econômicas que propiciam a subjugação e abafamento da voz dos marginalizados. Verificaremos como Mitchell dá voz a personagens subversoras da relação de desprezo, ataque ou mesmo silenciamento. Como aparato crítico-teórico, fundamentamos nossa pesquisa em Grosfoguel (2008), Mignolo (2007) e Castro-Goméz (2005), para discutir questões relacionadas à decolonialidade; em Foucault (2015), Rabinow e Rose (2006), para tratar do conceito de biopoder; em Butler (2003), Foucault (1980) e Stadniky (2007), para estudar as questões de identidade e gênero; em Arendt (2000), Bauman (2014), Butler e Spivak (2007), para debater acerca da liberdade dos subalternos; em Bauman (2014) e Eagleton (2004; 1996), para estudar conceitos relacionados à contemporaneidade; e, por fim, Bhabha (2013) e Santana (2008), para discutir questões relacionadas às diversas concepções de tempo. / Injustices and oppressions faced by subalterns have been studied for some decades by Subaltern Studies Groups, whether of Indian or Latin origin. With the aid of the group researches, contemporarily, excluded individuals acquire a voice, being heard and respected. Considering these facts, the dissertation aims to contribute to this fight by studying how subalternity is represented in characters in Cloud Atlas (2004), a novel written by David Mitchell. In our analysis, we will highlight the presence of hegemonic structure critiques in the construction of characters from subaltern groups. They belong to societies organized in a social and economic hierarchy, responsible for subjugation and muffling of subaltern’s voices. We will observe how Mitchell gives voice to characters who subvert the contempt, attack or even muzzling subalterns. As a criticaltheoretical approach, we base our research on Grosfoguel (2008), Mignolo (2007) and Castro-Goméz (2005), to discuss issues related to decoloniality; in Foucault (2015), Rabinow and Rose (2006), to deal with the concept of biopower; in Butler (2003), Foucault (1980) and Stadniky (2007), to study identity and gender issues; in Arendt (2000), Bauman (2014), Butler and Spivak (2007), to discuss subaltern freedom; in Bauman (2014) and Eagleton (2004, 1996), to study concepts related to contemporaneity; and finally, Bhabha (2013) and Santana (2008), to discuss issues related to different conceptions of time. / 2015/25282-4

abstract: Security has been one of the top concerns in cloud community while cloud resource abuse and malicious insiders are considered as top threats. Traditionally, Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS) have been widely deployed to manipulate cloud security, with the latter one providing additional prevention capability. However, as one of the most creative networking technologies, Software-Defined Networking (SDN) is rarely used to implement IDPS in the cloud computing environment because the lack of comprehensive development framework and processing flow. Simply migration from traditional IDS/IPS systems to SDN environment are not effective enough for detecting and defending malicious attacks. Hence, in this thesis, we present an IPS development framework to help user easily design and implement their defensive systems in cloud system by SDN technology. This framework enables SDN approaches to enhance the system security and performance. A Traffic Information Platform (TIP) is proposed as the cornerstone with several upper layer security modules such as Detection, Analysis and Prevention components. Benefiting from the flexible, compatible and programmable features of SDN, Customized Detection Engine, Network Topology Finder, Source Tracer and further user-developed security appliances are plugged in our framework to construct a SDN-based defensive system. Two main categories Python-based APIs are designed to support developers for further development. This system is designed and implemented based on the POX controller and Open vSwitch in the cloud computing environment. The efficiency of this framework is demonstrated by a sample IPS implementation and the performance of our framework is also evaluated. / Dissertation/Thesis / Masters Thesis Computer Science 2014

Made available in DSpace on 2014-06-12T15:57:46Z (GMT). No. of bitstreams: 2 arquivo3224_1.pdf: 1528247 bytes, checksum: a3554156b6142706a9da81ae71bcfd08 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Faculdade de Amparo à Ciência e Tecnologia do Estado de Pernambuco / Atualmente, os computadores vêm experimentando um aumento de capacidades, apesar de passarem por constante miniaturização e ganho de mobilidade. Em paralelo, a velocidade e a confiabilidade das conexões evoluem a passos largos. Para explorar esta nova relação entre comunicação em rede e processamento foi desenvolvido o conceito de computação em nuvem, na qual os serviços são oferecidos através de uma rede difusa e os consumidores destes não têm ciência de como os provedores realizam suas atividades. Devido à natureza heterogênea deste paradigma de provisão e consumo, a descrição e criação desta categoria de serviços têm sua dificuldade aumentada, visto que os produtos de diversos domínios devem funcionar sobre plataformas não padronizadas e ser oferecidos a consumidores diversos de forma direta, contudo mantendo sua funcionalidade. O uso de padrões é uma solução bastante difundida nos mais diversos ramos de criação de processos, pois prega o reuso de trabalho de desenvolvimento, dando um suporte histórico a cada novo processo criado a partir de um padrão. Este trabalho propõe uma forma de acelerar o desenvolvimento e a implantação de serviços para computação em nuvem através da divisão da criação em três etapas. As etapas relacionadas à criação são semiautomatizadas pelo uso de padrões de projeto e de desenvolvimento, enquanto a etapa de implantação é totalmente automatizada pelo uso de moldes de compilação

Os sistemas convectivos da região Amazônica possuem características microfísicas peculiares, que variam de um caráter convectivo marítimo (estação chuvosa) a continental (estação de transição seca-chuvosa). Essas características modulam a eletrificação desses sistemas, porém ainda não se sabe quais são os processos dominantes que intensificam o número de descargas elétricas de uma estação para outra: efeito dos aerossóis, termodinâmico, grande-escala ou topografia? Para responder à essa pergunta, o objetivo deste trabalho foi identificar e quantificar a importância de cada um desses efeitos na eletrificação dos sistemas convectivos da Amazônia. A metodologia foi baseada em análises de dados observacionais do experimento de campo DRYTOWET e em um modelo numérico com parametrizações de transferências de cargas e descargas elétricas. A análise do ciclo anual das descargas elétricas do tipo nuvem-solo (CGs) mostrou que a atividade elétrica dos sistemas precipitantes da região sudoeste da Amazônia aumenta durante a transição da estação seca para a estação chuvosa (Agosto a Setembro), associada aos sistemas convectivos com maior desenvolvimento vertical que acontecem nesse período. Com o estabelecimento da estação chuvosa (Novembro a Março), o número de CGs diminui porém a atividade elétrica ainda se mantêm. A porcentagem desses totais de CGs que tinham polaridade positiva (+CGs) tem média de 12% durante todo o ano, aumentando drasticamente para até 25% em Setembro, durante a transição entre as estações secas e chuvosa. Esse aumento da %+CGs ocorreu simultaneamente ao aumento da poluição atmosférica provocada pela queima de biomassa das pastagens realizada pelos fazendeiros locais, que as preparam para a agricultura e pecuária durante o início das primeiras chuvas. Por outro lado, o aumento da %+CGs das tempestades também ocorreu preferencialmente sobre a área de pastagem do estado de Rondônia. Através da análise de dados de radar dos sistemas precipitantes que ocorreram durante o experimento DRYTOWET, foi constatado que as tempestades positivas (tempestades que produzem mais de 50% de +CGs em 50% de seu tempo de vida) se formaram em ambientes mais secos e com alturas do nível de convecção por levantamento (NCL, altura da base da nuvem) maiores do que as demais tempestades (tempestades negativas), durante todo o experimento mas com maiores diferenças durante o final da estação seca (Setembro-Outubro). Com altura da base da nuvem mais elevada, a espessura da camada quente (ECQ - base da nuvem até a isoterma de 0oC) diminui, aumentando assim a velocidade das correntes ascendentes através de um melhor processamento da energia potencial disponível para convecção (CAPE) devido a um menor entranhamento. O aumento da velocidade das correntes ascendentes dentro da nuvem resulta em tempestades mais profundas e mais intensas. O efeito do aumento do NCL é uma característica das regiões com vegetação de pastagem, onde a razão entre o calor sensível e latente na superfície é maior do que as áreas florestadas, aumentando a altura da camada limite planetária. As diferenças de concentração total e distribuição de tamanho dos aerossóis devido ao aumento da poluição durante a transição entre as estações seca e chuvosa não foram conclusivas quanto a um possível efeito na distribuição de hidrometeoros das tempestade positivas e negativas, uma vez que o ciclo diurno da concentração dos aerossóis acompanha o ciclo diurno da camada limite planetária, que também regula o efeito da ECQ. Simulações numéricas com um modelo 1D de nuvem, acoplado à parametrizações de transferências de cargas elétricas entre hidrometeoros e raios, mostraram que a estrutura termodinâmica da atmosfera foi a maior responsável pela eletrificação das tempestades simuladas, aumentando a velocidade das correntes ascendentes. O efeito do aumento do número de aerossóis, que inibe da fase quente da nuvem e conseqüentemente fortalece a da fase fria da nuvem fornecendo mais vapor e gotículas de nuvem para essa região, provocou a diminuição da quantidade de granizo nas tempestades simuladas e o aumento de partículas agregadas menores, como os flocos de neve e graupel, diminuindo a freqüência de raios. / Amazonian convective systems have unique microphysical characteristics, varying from a maritime convective behavior (rainy season) to a continental behavior (wet-dry transition season). These characteristics modulate the electrification of these systems, however it is still not well understood which are the dominant processes that intensify the frequency of lightning from one season to another: aerosol effect, thermodynamics, large-scale variability, landscape or topography? To answer this question, the objective of this study was to identify and quantify the importance of each one of these effects on the electrification of convective systems over the Amazon. The methodology was based on the analysis of observational data from the field experiment DRYTOWET and a numerical model with charge transfer parameterizations and lightning discharges. The cloud-to-ground (CG) lightning discharges annual cycle presented that the electrical activity of the southwestern Amazonian precipitating systems increased during the transition between the dry and wet seasons (August to September), in association with the convective systems deepening. With the establishment of the wet season (November to March), the number of CGs decreased but the electrical activity continued. The mean annual percentage of cloud-to-ground lightning of positive polarity (+CGs) was 12%, increasing drastically to 25% in September during the transition between the dry and wet seasons. This percentage of +CGs raise happened simultaneously with the increase in the atmospheric pollution due to the pasture biomass burning, held by local farmers to prepare the soil for agriculture and livestock during the begging of first rains. On the other hand, the increase in %+CGs also occurred preferentially over pasture areas of Rondonia state. Through the analysis of radar precipitating systems that occurred during the field campaign DRYTOWET, it was noted that positive thunderstorms (storms that produced more than 50% of +CGs over 50% of their life time) were initiated in drier and higher lift condensation levels (cloud base height) environments than other storms (negative thunderstorms) during all the field experiment, especially in the end of the dry season (September-October). A higher cloud base height is associated with a shallower warm cloud depth (cloud base height to the 0oC isotherm) and consequently less entrainment, increasing the updrafts due to a more efficient processing of the convective available potential energy (CAPE). This increase in updrafts inside the clouds results in deeper and stronger thunderstorms. The higher cloud base heights is a characteristic from pasture regions, where the ratio between sensible and latent heats at surface is greater than forested areas, which increases the top of the planetary boundary layer. The differences in the aerosol total concentration and size distribution, due to the increase in the atmospheric pollution during the transition between the dry and wet seasons, were inconclusive in a possible aerosol effect in the strength of positive and negative thunderstorms, once the aerosol concentration diurnal cycle follows the cycle of the planetary boundary layer, that also regulates the warm cloud depth effect. Numerical simulation of an 1D cloud model, coupled with charge transfer between the hydrometeors, showed that the thermodynamic structure was the main responsible feature for cloud electrification, increasing the updraft velocities. The pollution effect was masked in simulations, which inhibit the warm precipitation and consequently strength the the mixed and cold regions of the cloud, was responsible for an increase in the number of smaller aggregated particles, like snow flakes and graupel, decreasing the electrification and lightning frequency.

Data storage is essential in many Internet services today. As the amountof generated data increases every day a way to store is needed. Relationaldatabases do not handle continuous growing data well. An option to it is touse NoSQL. XDIN Link¨ping is interested in developing an Internet serviceowhich uses non-relational type of data storage to store structured data. Thedata should be accessible to members of the service. The data storage doesnot make any assumption on what type of data is stored. Instead tags thatare attached to each entity are used to verify what type of data it is stored.This thesis provides a description of what NoSQL is and along with it theproposed database designs. Further it aims to investigate if it is reasonableto create a web service which uses NoSQL as the backend storage.

De nos jours, nous assistons à une énorme avancée des applications collaboratives mobiles. Ces applications tirentparti de la disponibilité croissante des réseaux de communication et de l’évolution impressionnante des dispositifsmobiles. Cependant, même avec un développement en accélération, ils demeurent toujours pauvres en ressources(une courte durée de vie des batteries et une connexion réseau instable) et moins sécurisés. Dans le cadre de notretravail, nous proposons une nouvelle approche basée sur le déploiement des tâches de collaboration mobile versle cloud. La gestion d’une virtualisation efficace assurant la continuité de la collaboration pour des réseaux pairà-pair est une tâche très difficile. En effet, l’aspect dynamique des groupes (où les utilisateurs peuvent joindre,quitter ou changer de groupes) ainsi qu’une vulnérabilité aux pannes peuvent affecter la collaboration. En outre,la conception de telles applications doit prendre en compte l’hétérogénéité des environnements cloud et mobile.Contrairement aux travaux existants , nous proposons une architecture réutilisable de haut niveau basée sur les patronsde conception et qui peut être facilement adaptée à plusieurs environnements clouds et mobiles hétérogènes.Nos modèles ont été utilisés comme base pour la conception de : (i) MidBox, une plate-forme virtuelle pour exécuterdes applications collaboratives mobiles sur un cloud privé et (ii) MobiRDF, un service de cloud décentralisépour la manipulation en temps réel des connaissances via des documents RDF partagés. / Nowadays we assist to an enormous progress of mobile collaborative applications. These applications take advantage of the increasing availability of communication networks and the impressive evolution of mobile devices. However, even with a developing acceleration, they are still poor in resources (short life of batteries andunstable network connections) and less secure. In the context of our work, we propose a new approach based on the deployment of mobile collaboration tasks to the cloud. The management of efficient virtualization ensuring continuity of collaboration in peer-to-peer networks is a very difficult task. Indeed, the dynamic aspect of the groups (where users can join, leave or change groups) and a vulnerability to failures can affect the collaboration.In addition, the design of such applications must consider the heterogeneity of cloud and mobile environments.Unlike existing works, we propose a reusable high-level architecture based on patterns design, which can be easily adapted to heterogeneous clouds and mobile environments. Our models have been used as basis for the design of:(i) MidBox, a virtual platform for running mobile collaborative applications on a private cloud and (ii) MobiRDFa decentralized cloud service for real-time manipulation of knowledge via shared RDF documents.

It was known for a long time that OpenStack has issues with scalability. Peer-to-Peer systems, on the other hand, have proven to scale well without significant reduction of performance. The objectives of this thesis are to study the challenges associated with P2P-enhanced clouds and present solutions for overcoming them. As a case study, we take the architecture of the P2P-enhanced OpenStack implemented at Ericsson that uses the CYCLON P2Pprotocol. We study the OpenStack architecture and P2P technologies and finally propose solutions and provide possibilities in addressing the challenges that are faced by P2P-enhanced OpenStack clouds. We emphasize mainly on a decentralized identity service and management of Virtual machine images. This work also investigates the characterization of P2P architectures for their use in P2P-enhanced OpenStack clouds. The results section shows that the proposed solution enables the existing P2P system to scale beyond what was originally possible. We also show that the P2P-enhanced system performs better than the standard OpenStack. / <p>Ericsson Cloud Research supported this work through the guidance of Dr. Fetahi Wuhib, Dr. Joao Monteiro Soares and Vinay Yadav, Experienced Researchers, Ericsson Cloud Research, Kista, Stockholm.</p>

Server selection is an important problem of cloud computing in which cloud service providers direct user demands to servers in one of the multiple data centers located in different geographical locations. The existing solutions usually assume homogeneity of cloud services (i.e., all users request the same type of service) and handle user demands in an individual basis which incurs high computational overhead. In this study, we propose a new and effective server selection scheme in which diversities of cloud services are taken into account. We focus on a specific cloud service, i.e., online video service, and assume that different videos have different bandwidth requirements. We group users into clusters and handle user demands on a cluster basis for faster and more efficient process. Firstly, we assume that user demands and bandwidth capacities of servers are given in the data centers, our problem is to assign the user demands to the servers under the bandwidth constraint, such that the overall latency (measured by the network distance) between the user clusters and the selected servers is minimized. We design a server selection system and formulate this problem as a linear programming formulation which can be solved by existing techniques. The system periodically executes our scheme and computes an optimal solution for server selection. User demands are assigned to the servers according to the optimal solution and the minimum overall latency can be achieved. The simulation results show that our scheme is significantly better than the random algorithm and the YouTube server selection strategy. Based on the first part, we take the storage capacities of servers constraint into consideration. In the second part, our new problem is to assign the user demands to the servers under the bandwidth and storage constraint, such that the function of overall latency (measured by the network distance) between the user clusters and the selected servers and standard deviation of traffic load of every server in the system is minimized. We design a server selection system and formulate this problem which can be solved by existing techniques. User demands are assigned to the servers according to the optimal solution and the two goals (minimum overall latency and the most balanced traffic load) can be achieved. The simulation results show the influence of different weights of these two goals on the user demands assigning.

As a result of evergrowing data and recent interest in storing and analyzing it, distributed storage systems (DSS), which is also known as cloud storage, have become one of the most important research areas in the literature. Not only such networks are being used as backbone systems for companies like Google, Microsoft and Facebook but also they have accelerated the growth of cloud computing, which is an essential business line for institutions such as IBM, Amazon and Salesforce. In this dissertation, the focus is on the storage side of cloud in order to address the important questions in designing such systems. First, coding theoretic approach is taken to handle correlated failures of multiple storage nodes. In particular, this dissertation studies distributed storage systems that can provide resilience against correlated failure patterns that affect the availability of multiple storage nodes, i.e., power loss that may affect multiple disks. Maximum file size that can be stored in such DSS is studied and then optimal code constructions are provided. This dissertation also studies cloud storage systems that prevent data loss from mixed failure patterns of disks and sectors in disk drives. Specifically, a general code construction is proposed to overcome such failures for any given parameter set. Due to its large field size requirement of proposed construction, a relaxation on the efficiency of storage system is considered to provide codes with smaller field sizes. Maintenance of cloud storage systems is also studied. To that end, this dissertation first studies the maintenance of DSS that include a backup node, which is called hierarchical DSS. Hierarchical DSS can model cellular networks such as femtocell as well as caching in wireless networks. In particular, we present an upper bound on the file size that can be stored over hierarchical DSS and propose optimal code constructions. Then, maintenance cost and data access cost for users of such DSS are studied. Lastly, mobility effects of cloud storage over wireless devices are studied. Specifically, an analysis on the mobile cloud storage system that initiates the maintenance process after certain number of devices remains in the network is performed and different maintenance strategies are proposed that are optimal with respect to average cost in certain mobility regimes.

Malicious software (malware) attacks are an ever-increasing cyber-security problem. One reason for this trend is the widespread adoption of packing technology as a way to mask the semantics of binary instructions, hiding them from detection. Packing is so successful that it is estimated 70-80% of malicious programs utilize it to avoid detection [1]. The popularity of virtualization provides new tools for dealing with this threat. Researchers have successfully used facilities provided by virtualization to develop new ways of detecting and analyzing packed and encrypted malware. Methods like these typically require changes to the virtualization platform, making them difficult to deploy as well as hard to reuse. This thesis presents Maitland, a proof-of-concept unpacking system which achieves similar functionality to existing research, using paravirtualization extensions instead of requiring changes to the hypervisor. During our experiments, Maitland successfully exposed instructions in software that was packed by the UPX and gzexe packers. Maitland’s avoidance of changes to the hypervisor means it is better suited for quick deployment in a cloud environment. / Graduate