Quality of services adaptation model for distributed multimedia application based on RTP protocol on IP network

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Architectural support for ubiquitous access to multimedia content

Tese de doutoramento. Engenharia Electrotécnica e de Computadores (Telecomunicações). Faculdade de Engenharia. Universidade do Porto. 200

Large scale collaborative virtual environments

[N.B. Pagination of eThesis differs from printed thesis. The content is identical.] This thesis is concerned with the theory, design, realisation and evaluation of large-scale collaborative virtual environments. These are 3D audio-graphical computer generated environments which actively support collaboration between potentially large numbers of distributed users. The approach taken in this thesis reflects both the sociology of interpersonal communication and the management of communication in distributed systems. The first part of this thesis presents and evaluates MASSIVE-1, a virtual reality tele-conferencing system which implements the spatial model of interaction of Benford and Fahlén. The evaluation of MASSIVE-1 has two components: a user-oriented evaluation of the system’s facilities and the underlying awareness model; and a network-oriented evaluation and modelling of the communication requirements of the system with varying numbers of users. This thesis proposes the “third party object” concept as an extension to the spatial model of interaction. Third party objects can be used to represent the influence of context or environment on interaction and awareness, for example, the effects of boundaries, rooms and crowds. Third party objects can also be used to introduce and manage dynamic aggregates or abstractions within the environments (for example abstract overviews of distant crowds of participants). The third party object concept is prototyped in a second system, MASSIVE-2. MASSIVE-2 is also evaluated in two stages. The first is a user-oriented reflection on the capabilities and effectiveness of the third party concept as realised in the system. The second stage of the evaluation develops a predictive model of total and per-participant network bandwidth requirements for systems of this kind. This is used to analyse a number of design decisions relating to this type of system, including the use of multicasting and the form of communication management adopted

Large scale collaborative virtual environments

[N.B. Pagination of eThesis differs from printed thesis. The content is identical.] This thesis is concerned with the theory, design, realisation and evaluation of large-scale collaborative virtual environments. These are 3D audio-graphical computer generated environments which actively support collaboration between potentially large numbers of distributed users. The approach taken in this thesis reflects both the sociology of interpersonal communication and the management of communication in distributed systems. The first part of this thesis presents and evaluates MASSIVE-1, a virtual reality tele-conferencing system which implements the spatial model of interaction of Benford and Fahlén. The evaluation of MASSIVE-1 has two components: a user-oriented evaluation of the system’s facilities and the underlying awareness model; and a network-oriented evaluation and modelling of the communication requirements of the system with varying numbers of users. This thesis proposes the “third party object” concept as an extension to the spatial model of interaction. Third party objects can be used to represent the influence of context or environment on interaction and awareness, for example, the effects of boundaries, rooms and crowds. Third party objects can also be used to introduce and manage dynamic aggregates or abstractions within the environments (for example abstract overviews of distant crowds of participants). The third party object concept is prototyped in a second system, MASSIVE-2. MASSIVE-2 is also evaluated in two stages. The first is a user-oriented reflection on the capabilities and effectiveness of the third party concept as realised in the system. The second stage of the evaluation develops a predictive model of total and per-participant network bandwidth requirements for systems of this kind. This is used to analyse a number of design decisions relating to this type of system, including the use of multicasting and the form of communication management adopted

Continuously available virtual environments

This thesis presents a framework for continuously available persistent collaborative virtual environments which is fundamentally more flexible than current approaches. Whereas existing systems allow the artefacts in the environment and the application behaviours of those artefacts to be changed at run time, they still need to be shut down if the infrastructure mechanisms of the system need to be changed. The framework presented by this thesis pushes run-time extensibility to a lower level allowing previously static infrastructure mechanisms and application level behaviours to be replaced and extended in a uniform way. By associating infrastructure mechanisms with artefacts in the same way that application behaviours are associated, the framework allows multiple alternative infrastructure mechanisms to coexist within the virtual environment system. Rather than applying a single infrastructure mechanism to all artefacts in a virtual environment, mechanisms can be tailored to an artefact’s role, optimising the operation of each artefact. This allows a wider range of artefact behaviours and so applications to be supported by a single virtual environment. Infrastructure level behaviours may implement a single infrastructure mechanism or multiple mechanisms, allowing the framework to explicitly present the complex interdependencies which can exist between infrastructure mechanisms such as persistence and consistency. In addition to providing greater run-time flexibility for continuously available persistent virtual environments, the framework allows infrastructure mechanisms to be easily developed, compared, tested and configured, making it a useful test bed for the development of future infrastructure mechanisms. After reviewing existing virtual environment systems and related systems, the thesis presents an experiment which reveals some of the problems existing with current approaches to persistence in virtual environments. The thesis then describes the framework discussed above and the issues involved in its realisation before evaluating the current prototype. Finally some conclusions are presented and future work discussed

Continuously available virtual environments

This thesis presents a framework for continuously available persistent collaborative virtual environments which is fundamentally more flexible than current approaches. Whereas existing systems allow the artefacts in the environment and the application behaviours of those artefacts to be changed at run time, they still need to be shut down if the infrastructure mechanisms of the system need to be changed. The framework presented by this thesis pushes run-time extensibility to a lower level allowing previously static infrastructure mechanisms and application level behaviours to be replaced and extended in a uniform way. By associating infrastructure mechanisms with artefacts in the same way that application behaviours are associated, the framework allows multiple alternative infrastructure mechanisms to coexist within the virtual environment system. Rather than applying a single infrastructure mechanism to all artefacts in a virtual environment, mechanisms can be tailored to an artefact’s role, optimising the operation of each artefact. This allows a wider range of artefact behaviours and so applications to be supported by a single virtual environment. Infrastructure level behaviours may implement a single infrastructure mechanism or multiple mechanisms, allowing the framework to explicitly present the complex interdependencies which can exist between infrastructure mechanisms such as persistence and consistency. In addition to providing greater run-time flexibility for continuously available persistent virtual environments, the framework allows infrastructure mechanisms to be easily developed, compared, tested and configured, making it a useful test bed for the development of future infrastructure mechanisms. After reviewing existing virtual environment systems and related systems, the thesis presents an experiment which reveals some of the problems existing with current approaches to persistence in virtual environments. The thesis then describes the framework discussed above and the issues involved in its realisation before evaluating the current prototype. Finally some conclusions are presented and future work discussed

Pornography as the agent of technological change : the transformation of perception of embodiment and privacy

The aim of this rigorosum thesis is the relationship between pornography and new technologies. The influence of this relationship on perception of embodiment and privacy is also disscussed. The thesis describes the technologies and related procedures which came into contact with pornographic content at an early stage of their existence and has been affected by this specific segment of the market. This paper also examines the aspects of these effects and focuses on the related penetration of these technologies among the general public. It also reflects the possible impacts on individuals and whole human society. The thesis is divided into four main chapters. The first chapter focuses on videocassette recorders, a technology that has been affected by pornography in past. The second chapter summarizes the impact of pornography on the Internet, which represents the technology we encounter every day, and is often an integral part of our lives. The third chapter outlines the possible future development of relationship between pornography and new technologies, while analyzes the driving forces of the influence of pornography. The final chapter reflects changes in the perception of embodiment and privacy in a society that was brought by the pornography and related technologies. Powered by TCPDF (www.tcpdf.org)Tématem rigorózní práce je vztah pornografie a nových technologií, včetně vlivu tohoto vztahu na vnímání tělesnosti a soukromí ve společnosti. Práce popisuje technologie a s nimi související postupy, které v rané fázi své existence přišly do kontaktu s pornografickým obsahem, a byly tímto specifickým segmentem trhu ovlivněny. Zároveň tato práce zkoumá aspekty těchto vlivů a zaměřuje se na související pronikání těchto technologií mezi běžnou veřejnost. Přitom jsou též reflektovány případné dopady na lidskou společnost či jednotlivce. Rigorózní práce je rozdělena do čtyř hlavních kapitol, které svým obsahem odpovídají jednotlivým úsekům časového spektra, přičemž poslední kapitola reflektuje právě změny mezi lidmi. Úvodní kapitola se zabývá problematikou kazetových videorekordérů, tedy technologie, která byla ovlivněna pornografií, stala se běžnou součástí domácností, ale již se prakticky nevyužívá. Druhá kapitola shrnuje vliv pornografie na Internet, který reprezentuje technologii, s níž se setkáváme každý den, a je mnohdy nedílnou součástí našich životů. Třetí kapitola pak nastiňuje možný budoucí vývoj vztahu pornografie a nových technologií, když rozebírá hnací síly pornografického vlivu, který ilustruje za pomocí technologií a postupů, jenž pozvolna pronikají i do domácností. Závěrečná kapitola reflektuje...Institute of Information Studies and LibrarianshipÚstav informačních studií a knihovnictvíFaculty of ArtsFilozofická fakult