Thesis--PlanB (M.S.)--University of Wisconsin--Stout, 2004. / Includes bibliographical references.

Thesis (M.Sc. (Computer Science)) - Rhodes University, 2009.

Stuttgart, FH, Diplomarb., 2002.

Ulm, Univ. Diss., 2007.

Dissertation (Ph.D.)--Worcester Polytechnic Institute. / Keywords: Streaming MPEG, User Study, Video Quality, Forward Error Correction, Temporal Scaling, Quality Scaling. Includes bibliographical references (p.186-198).

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 86-91). Also available in electronic version.

This thesis examines the transformations of music circulation and consumption brought about by new media platforms. Specifically, it shows how the social and technical design of online music platforms link the consumption of music immanently to its circulation. The thesis makes contributions to ethnomusicology, media studies, and digital anthropology, as well as to the study of music's technical cultures. It is based on a comparative ethnographic study of music circulation and consumption within two field sites: the commercial streaming service Spotify and the extralegal, unlicensed peer to peer platform 'Jekyll'. Governance comes to the fore in both sites: the study shows how practices of music curation, collection and consumption are regulated by the technical design of these platforms. Surprisingly, music consumption and circulation on Jekyll generates a variety of social relations, including pronounced social hierarchies. This is far less apparent on Spotify, due to the platform's individuated mode of address. The subjectivities of online music consumers are mediated by both their personal histories and by the broader technical genealogies of the platforms they use. The thesis illuminates the mutual interdependencies of the licensed and extralegal spheres, two domains often portrayed as not only separate but antagonistic. It also provides insight into the hybrid modes of exchange that generate digital music platforms. Through examining the entailments of circulatory participation, the study offers new insights into digital polymedia and to labour, exchange and governmentality online, as well as providing nuanced understandings of the ownership and collection of music in digital environments. Moreover, it advances new concepts to identify core aspects of digital music cultures, namely 'circulatory maintenance' and 'circumvention technology'. The thesis shows overall how Spotify and Jekyll are not merely emblematic of emergent consumption practices engendered by new media, but are bound up in the mutual co-creation of culture, engendering novel musical subjectivities, practices, socialities and ideologies. The complex musical, technical and social assemblages formed around music circulation online point to the affective potentials of music itself, producing inalienable attachments to the objects through which music is formatted, experienced, and circulated.

Micro-devices are developed for uses in targeted drug delivery and microscale manipulation. Here we numerically and analytically study two promising devices in early stages of development. Firstly, we study Armoured Microbubbles (AMBs) which can self-propel as artificial microswimmers or facilitate microfluidic mixing in a channel when held stationary on a wall. Secondly, we study an artificial cilium, which due to its unique design, when placed in an array, easily produces a metachronal wave for fluid transportation. The Armoured Microbubble was designed by our experimental collaborators (group of Philippe Marmottant, University Grenoble Alpes) and consists of a partial hollow sphere, inside which a bubble is caught. Under ultrasound the bubble oscillates, generating a streaming flow in the surrounding fluid and producing a net force. Motivated by the AMB but considering initially a general setup, using matched asymptotic expansions we calculate the streaming flow around a spherical body undergoing arbitrary, but known, small-amplitude surface shape oscillations. We then specialise back to the AMB and consider its excitation under ultrasound, using a potential flow model with mixed boundary conditions, to identify the resonant frequencies and mode shapes, including the dependence of the resonance on the AMB shape parameters. Returning to our general streaming model, we applied the mixed boundary conditions directly to this model, calculating the streaming around the AMB, in good agreement with experiments. Using hydrodynamic images and linear superposition, this model was extended to incorporate one wall, and AMB compounds. We then study the streaming flows generated by arrays of AMBs in confined channels, by modelling each AMB as its leading order behaviour (with corrections where required) and superposing the individual flow fields of all the AMBs. We identified the importance of two confining walls on the streaming flow around the array, and compared these flows to experiments in five cases. Motivated by this setup, we theoretically considered the extension of a two fluid interface passing through an AMB array to quickly identify good AMB arrays for mixing. We then studied the second artificial micro-device: an artificial cilium. Tsumori et. al. produced a cilium of PDMS containing aligned ferromagnetic filings, which beat under a rotating magnetic field. We modelled a similar cilium but assumed paramagnetic filings, using a force model balancing elastic, magnetic and hydrodynamic forces identifying the cilium beat pattern. This agreed with our equilibrium model and asymptotic analysis. We then successfully identified that the cilium applies the most force to the surrounding fluid at an intermediate value of the two dimensionless numbers quantifying the dynamics.

Le trafic vidéo a subi une augmentation fulgurante sur Internet ces dernières années. Pour pallier à cette importante demande de contenu vidéo, la technologie du streaming adaptatif sur HTTP est utilisée. Elle est devenue par ailleurs très populaire car elle a été adoptée par les différents acteurs du domaine de la vidéo streaming. C’est une technologie moins couteuse qui permet aux fournisseurs de contenu, la réutilisation des serveurs web et des caches déjà déployés. En plus, elle est exempt de tout blocage car elle traverse facilement les pare-feux et les translations d’adresses sur Internet. Dans cette thèse, nous proposons une nouvelle méthode de vidéo streaming adaptatif appelé “Backward-Shifted Coding (BSC)”. Il se veut être une solution complémentaire au standard DASH, le streaming adaptatif et dynamique utilisant le protocole HTTP. Nous allons d’abord décrire ce qu’est la technologie BSC qui se base sur le codec (encodeur décodeur) à multi couches SVC, un algorithme de compression extensible ou évolutif. Nous détaillons aussi l’implémentation de BSC dans un environnement DASH. Ensuite,nous réalisons une évaluation analytique de BSC en utilisant des résultats standards de la théorie des files d’attente. Les résultats de cette analyse mathématique montrent que le protocole BSC permet de réduire considérablement le risque d’interruption de la vidéo pendant la lecture, ce dernier étant très pénalisant pour les utilisateurs. Ces résultats vont nous permettre de concevoir des algorithmes d’adaptation de qualité à la bande passante en vue d’améliorer l’expérience utilisateur. Ces algorithmes permettent d’améliorer la qualité de la vidéo même étant dans un environnement où le débit utilisateur est très instable.La dernière étape de la thèse consiste à la conception de stratégies de caching pour optimiser la transmission de contenu vidéo utilisant le codec SVC. En effet, dans le réseau, des serveurs de cache sont déployés dans le but de rapprocher le contenu vidéo auprès des utilisateurs pour réduire les délais de transmission et améliorer la qualité de la vidéo. Nous utilisons la programmation linéaire pour obtenir la solution optimale de caching afin de le comparer avec nos algorithmes proposés. Nous montrons que ces algorithmes augmentent la performance du système tout en permettant de décharger les liens de transmission du réseau cœur. / Due to the growth of video traffic over the Internet in recent years, HTTP AdaptiveStreaming (HAS) solution becomes the most popular streaming technology because ithas been succesfully adopted by the different actors in Internet video ecosystem. Itallows the service providers to use traditional stateless web servers and mobile edgecaches for streaming videos. Further, it allows users to access media content frombehind Firewalls and NATs.In this thesis we focus on the design of a novel video streaming delivery solutioncalled Backward-Shifted Coding (BSC), a complementary solution to Dynamic AdaptiveStreaming over HTTP (DASH), the standard version of HAS. We first describe theBackward-Shifted Coding scheme architecture based on the multi-layer Scalable VideoCoding (SVC). We also discuss the implementation of BSC protocol in DASH environment.Then, we perform the analytical evaluation of the Backward-Sihifted Codingusing results from queueing theory. The analytical results show that BSC considerablydecreases the video playback interruption which is the worst event that users can experienceduring the video session. Therefore, we design bitrate adaptation algorithms inorder to enhance the Quality of Experience (QoE) of the users in DASH/BSC system.The results of the proposed adaptation algorithms show that the flexibility of BSC allowsus to improve both the video quality and the variations of the quality during thestreaming session.Finally, we propose new caching policies to be used with video contents encodedusing SVC. Indeed, in DASH/BSC system, cache servers are deployed to make contentsclosed to the users in order to reduce network latency and improve user-perceived experience.We use Linear Programming to obtain optimal static cache composition tocompare with the results of our proposed algorithms. We show that these algorithmsincrease the system overall hit ratio and offload the backhaul links by decreasing thefetched content from the origin web servers.

Made available in DSpace on 2014-06-12T16:01:27Z (GMT). No. of bitstreams: 2 arquivo8983_1.pdf: 2694145 bytes, checksum: eada2ca72336a7b81aacb802940a6312 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / A popularização do serviço de Internet e a redução de custo facilitaram o acesso de usuários a diversos provedores de conteúdo, sejam estes baseados em voz, vídeo ou qualquer outro recurso de multimídia. Consequentemente aumentam os benefícios de ter uma rede de comunicações de melhor resiliência, pois quando uma conexão falha os dados podem fluir por conexões alternativas, reduzindo a probabilidade de perdas de pacotes e falhas na transmissão. Dessa forma, abre-se um novo cenário de estudo que tem a intenção de verificar e propor melhoras em formas de uso dos protocolos de comunicação que tenham o objetivo de tornar confiável a escolha dos melhores caminhos de transmissão para cada tipo de conteúdo. Para a transmissão de stream de vídeo, a escolha do protocolo de transporte é tão importante quanto a escolha de algoritmos e estruturas de dados em relação à aplicação rede. O estudo do desempenho de protocolos de rede de transportes é essencial para o desenvolvimento de protocolos tolerantes a falhas. A avaliação de políticas combinado com o caminho de transmissão, e os limiares de detecção de falhas, largura de banda, atrasos e perda de vazão são avaliados através da simulação dos diferentes protocolos de transmissão utilizado. O comportamento dos protocolos são verificados, comparando o tráfego considerando caminhos alternativos simétricas e assimétricas. O protocolo escolhido para o estudo é o UDP, devido à sua popularidade e sua tolerância a perda. Mostramos neste estudo que a configuração do tamanho do GOP (Group Of Picture) e a utilização correta do tamanho do Frame do UDP podem contribuir para uma transmissão de Vídeo Stream com melhor qualidade utilizando-se dos recursos de conexões disponíveis (seleção de caminhos) na rede