Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 57-61). Also available in electronic version.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 164-170). Also available in electronic version.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 100-104). Also available in electronic version.

Brandenburgische Techn. Universiẗat, Diss., 2004--Cottbus.

Orientador: Roberta Spolon / Banca: Marcos Antônio Cavenaghi / Banca: Ronaldo Augusto de Lara Gonçalves / Resumo: O processo de compartilhamento de arquivos passou por grande evolução desde a criação dos computadores, até os dias atuais. Esta evolução teve início com o compartilhamento de dados em computadores de grande porte, passando pela criação das mídias removíveis e, posteriormente, beneficiando-se dos avanços nas tecnologias de redes de computadores. Nesta última, é possível verificar duas fases distintas, a primeira, em que a arquitetura predominante foi cliente/servidor, e a segunda, na qual busca-se voltar às origens da Internet, e utilizar largamente o conceito de computação peer-to-peer. Apesar de todo avanço ocorrido com o compartilhamento de arquivos peer-to-peer, desde seu surgimento no final da década de noventa até os dias atuais, verifica-se que todo o avanço ocorrido ainda não foi suficiente para garantir a plena excelência no que esta tecnologia foi proposta, facilitar a troca de arquivos entre usuários e sistemas. Assim, esta dissertação apresenta um modelo de indexação e acesso a arquivos compartilhados, de maneira totalmente descentralizada e autônoma. Além disso, busca-se criar mecanismos de acesso ao conteúdo compartilhado através de padrões da indústria, oferecendo acesso a estes arquivos para diversas aplicações e sistemas, por exemplo, navegadores web, o qual foi foco de um estudo de caso neste trabalho, onde foi possível verificar todos os benefícios e viabilidade de tal modelo. / Abstract: The file sharing process has evolved significantly since the creation of the first personal computers to the present days. Such evolution begun with the possibility of data sharing among the users of a same supercomputer, passed through the creation of removable storage devices and, after that, took advantage in the technology advances in computer networks. In this last phase, it is possible to distinguish two different approaches one based on a client-server architecture, and another aiming to use the peer-to-peer concepts for data access. The growth in the adoption of peer-to-peer approaches, however, still have not been enough to guarantee the primary goal of this approach, which is to simplify access to shared data, due to the existence of multiple incompatible peer-to-peer networks. In this context, this dissertation presents a completely decentralized and autonomic approach to data indexing and access. In this sense, this approach intends to provide mechanisms to access data stored on independent peer-to-peer networks using industry standards, and offering access to such data to user and system applications, such as the web browsers, which was the focus of study case in this work, and made possible to verify all it's benefits and feasibility. / Mestre

Online social networks (OSNs) have become the most popular Internet application that attracts billions of users to share information, disseminate opinions and interact with others in the online society. The unprecedented growing popularity of OSNs naturally makes using social network services as a pervasive phenomenon in our daily life. The majority of OSNs service providers adopts a centralised architecture because of its management simplicity and content controllability. However, the centralised architecture for large-scale OSNs applications incurs costly deployment of computing infrastructures and suffers performance bottleneck. Moreover, the centralised architecture has two major shortcomings: the single point failure problem and the lack of privacy, which challenges the uninterrupted service provision and raises serious privacy concerns. This thesis proposes a decentralised approach based on peer-to-peer (P2P) networks as an alternative to the traditional centralised architecture. Firstly, a self-organised architecture with self-sustaining social network adaptation has been designed to support decentralised topology maintenance. This self-organised architecture exhibits small-world characteristics with short average path length and large average clustering coefficient to support efficient information exchange. Based on this self-organised architecture, a novel decentralised service discovery model has been developed to achieve a semantic-aware and interest-aware query routing in the P2P social network. The proposed model encompasses a service matchmaking module to capture the hidden semantic information for query-service matching and a homophily-based query processing module to characterise user’s common social status and interests for personalised query routing. Furthermore, in order to optimise the efficiency of service discovery, a swarm intelligence inspired algorithm has been designed to reduce the query routing overhead. This algorithm employs an adaptive forwarding strategy that can adapt to various social network structures and achieves promising search performance with low redundant query overhead in dynamic environments. Finally, a configurable software simulator is implemented to simulate complex networks and to evaluate the proposed service discovery model. Extensive experiments have been conducted through simulations, and the obtained results have demonstrated the efficiency and effectiveness of the proposed model.

Carsharing has been discussed as one of the most prominent examples of the sharing economy. The worldwide growth of services whereby consumers share access to cars rather than owning a car themselves could be a sustainable solution to environmental problems. However, first research indicates that consumers' environmental concerns play a minor role for using a carsharing compared to financial considerations. Moreover, prior research on B2C carsharing services may not be applicable to P2P services. The current research addresses this gap by investigating the role of sustainability in B2C and P2P carsharing from consumers' perspective. By applying quantitative as well as qualitative methods three studies show that consumers' image of carsharing is "greener" than owning a car and that environmental concerns play a role when consumers decide to use P2P service over B2C services. However, interviews with carsharing users indicate that the sustainable impact of carsharing is rather perceived as a positive side effect than a main argument for carsharing. This should be considered by policy makers and marketers when promoting carsharing because of sustainable benefits.

Made available in DSpace on 2014-06-12T16:01:05Z (GMT). No. of bitstreams: 2 arquivo7156_1.pdf: 2405287 bytes, checksum: 63f88801321ea61b8de43e420495d1b8 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2005 / A tecnologia de Voz sobre IP (VoIP) nasceu da necessidade da convergência das redes de telefonia e dados, aproveitando uma infra-estrutura de alcance mundial, a Internet. Esta tecnologia traz como vantagem a redução dos custos telefônicos, além da possibilidade de agregar novos serviços à telefonia. A tecnologia de Voz sobre IP é o resultado da pesquisa em busca de novas soluções tecnológicas, numa área que movimenta milhões em dólares, a área de telecomunicações, podendo se tornar um fenômeno na Internet, assim como os aplicativos de e-mails e mensagens instantâneas. Muitas iniciativas de projetos de VoIP têm surgido nos últimos anos. Dentre essas iniciativas temos o Skype, um aplicativo VoIp de grande sucesso. O Skype é um aplicativo de VoIP que usa a tecnologia peer-to-peer (P2P) híbrida, chamando atenção pela qualidade de transmissão da voz. O Skype é uma empresa de telefonia virtual, oferecendo chamadas telefônicas gratuitas entre computadores no mundo inteiro. Possui, ainda, as soluções SkypeIn e SkypeOut para o acesso a Rede Pública de Telefonia. Outra iniciativa de aplicativos na tecnologia VoIP é o XVoice. O XVoice foi um dos resultados do Grupo de Trabalho GT-P2P da Rede Nacional de Pesquisa (RNP), sendo projetado para avaliar o tráfego de voz na rede da RNP. O levantamento de requisitos para desenvolver o XVoice demandou um estudo aprofundado sobre o Skype e os protocolos e codecs que são utilizados em aplicações de Voz sobre IP. O XVoice é um aplicativo VoIP que usa a tecnologia peer-to-peer pura. Peer-to-peer é um modelo de comunicação no qual cada nó tem as mesmas capacidades e responsabilidades, e ambos podem iniciar uma sessão de comunicação, contrastando com o modelo cliente/servidor. O objetivo deste trabalho é avaliar os aplicativos de VoIP Skype e XVoice, descrevendo a metodologia e ferramentas utilizadas nesta avaliação. Na avaliação realizada neste trabalho, observou-se que os aplicativos Skype e XVoice possuem desempenhos similares, conforme mostrado nos resultados obtidos

This Master thesis is a contribution to develope Multimedia security mechanisms for various P2P file sharing environments. Objective of this research thesis is to design a software tool for Multimedia business environments to fight against the copyright infringement in various P2P file sharing networks. In order to fulfil this objective, a combined implementation of two independent mechanisms designed at Fraunhofer IPSI is required. So far, the combined implementation does not yet exist for any P2P network. So, the first objective is to design a most comprehensive architecture for their implementation and the second objective is to validate that implementation built on top of the architecture. To do so, we have chosen BitTorrent network for implementation and validation. / The main objective of this research thesis work is to design a software tool for identifying copyright violated works in various P2P networks. In fact, P2P networks are the prominent networks for such copyright violations. To do so, a combined implementation of two independent mechanisms described in chapter 2 is required. This combined implementation prior to this thesis work had not existed in the form of a concrete software tool. So, the first objective is to design a most comprehensive architecture for their implementation and the second objective is to validate that implementation built on our architecture. Hence we have chosen BitTorrent network for implementation and validation. The mechanisms we addressed in our implementation are: Passive Mechanism: Digital Watermarking is the passive mechanism which is used to add information to multimedia files to be protected. This active part is just used to achieve our goal but not focused in validation because of the reason mentioned in the 1.4 section Active Search Mechanism: In order to fight against illegal copies an active search mechanism scanning for potential copyright violations is needed. Any P2P network implementation must maintain this framework extendable to other P2P networks. This is the area focused in validation phase. / gansudkum@gmail.com

Financial journals have just begun to examine the implications of unsecured fixed-rate loans between lenders and borrowers administered over the internet. This study observes 31,550 loans issued between June 2007 and April 2013 with a 36-month term, that are fully paid or charged off, based on a data set from the largest P2P lending website. Initial findings within peer-to-peer (P2P) lending markets have identified that social disclosures may influence these markets. The result of this analysis unambiguously confirms social disclosures influence lenders and the factors significant for funding a loan are inconsistent with the factors significant to repayment of the loan. Prescriptive filters based on social disclosures can improve the likelihood of selecting a creditworthy borrower and increase the models explanatory power. The study finds that distinct forms of social disclosure and specific content within social disclosures predict the amount of funding received and probability of loan repayment.