In recent years, the high maintenance cost of centralized video on demand sys tems has led to the development of peer to peer video on demand systems. These peer to peer systems help to remove the cost and bandwidth limitations of a centralized group of servers. In a peer to peer scenario, the publisher and a small set of peers who were published to must handle all video requests. If many peers request a video after it is released, the small set of peers with the video cached may not have enough bandwidth to satisfy all requests. This situation is known as a flash crowd. We propose a hybrid peer to peer framework that allows publishers to publish videos before release time. For marketing purposes, it is common for videos that are ready for distribution to be kept from being released until a preset release time. By distributing a video before the release time, more peers will have the video at release time, thus allowing more requests to be handled. A hybrid peer to peer encryption management system is used to prevent users from viewing videos before release time. In order to determine who to distribute a video to before users are allowed to view the video, we design a hybrid peer to peer subscription system. In this system, users may specify interest in sets of videos and are notified of new videos matching the interest so that retrieval may start. Finally, we modify an existing peer to peer video on demand framework to better handle concurrent streaming and downloading. Our experiments show that this framework can greatly increase a peer to peer streaming system’s ability to handle flash crowd situations.

In recent years, the high maintenance cost of centralized video on demand sys tems has led to the development of peer to peer video on demand systems. These peer to peer systems help to remove the cost and bandwidth limitations of a centralized group of servers. In a peer to peer scenario, the publisher and a small set of peers who were published to must handle all video requests. If many peers request a video after it is released, the small set of peers with the video cached may not have enough bandwidth to satisfy all requests. This situation is known as a flash crowd. We propose a hybrid peer to peer framework that allows publishers to publish videos before release time. For marketing purposes, it is common for videos that are ready for distribution to be kept from being released until a preset release time. By distributing a video before the release time, more peers will have the video at release time, thus allowing more requests to be handled. A hybrid peer to peer encryption management system is used to prevent users from viewing videos before release time. In order to determine who to distribute a video to before users are allowed to view the video, we design a hybrid peer to peer subscription system. In this system, users may specify interest in sets of videos and are notified of new videos matching the interest so that retrieval may start. Finally, we modify an existing peer to peer video on demand framework to better handle concurrent streaming and downloading. Our experiments show that this framework can greatly increase a peer to peer streaming system’s ability to handle flash crowd situations.

Thesis--Lund Institute of Technology, 1993.

Thesis--Lund Institute of Technology, 1993.

Inaug.-Diss.--Jena. / Vita. Bibliography: p. [42]-45.

In recent years, the high maintenance cost of centralized video on demand sys tems has led to the development of peer to peer video on demand systems. These peer to peer systems help to remove the cost and bandwidth limitations of a centralized group of servers. In a peer to peer scenario, the publisher and a small set of peers who were published to must handle all video requests. If many peers request a video after it is released, the small set of peers with the video cached may not have enough bandwidth to satisfy all requests. This situation is known as a flash crowd. We propose a hybrid peer to peer framework that allows publishers to publish videos before release time. For marketing purposes, it is common for videos that are ready for distribution to be kept from being released until a preset release time. By distributing a video before the release time, more peers will have the video at release time, thus allowing more requests to be handled. A hybrid peer to peer encryption management system is used to prevent users from viewing videos before release time. In order to determine who to distribute a video to before users are allowed to view the video, we design a hybrid peer to peer subscription system. In this system, users may specify interest in sets of videos and are notified of new videos matching the interest so that retrieval may start. Finally, we modify an existing peer to peer video on demand framework to better handle concurrent streaming and downloading. Our experiments show that this framework can greatly increase a peer to peer streaming system’s ability to handle flash crowd situations. / Science, Faculty of / Computer Science, Department of / Graduate

Avec le développement et la multiplication des appareils connectés dans tous les domaines, de nouvelles solutions pour le traitement de flux de données ont vu le jour. Cette thèse s'inscrit dans ce contexte: elle a été réalisée dans le cadre du projet FUI Waves, une plateforme de traitement de flux distribués. Le cas d'usage pour le développement a été la gestion des données provenant d'un réseau de distribution d'eau potable, plus précisément la détection d'anomalie dans les mesures de qualité et leur contextualisation par rapport à des données extérieures. Plusieurs contributions ont été réalisées et intégrées à différentes étapes du projet, leur évaluation et les publications liées témoignant de leur pertinence. Celles-ci se basent sur une ontologie que j'ai spécifiée depuis des échanges avec les experts du domaine travaillant dans chez le partenaire métier du projet. L'utilisation de données géographiques a permis de réaliser un système de profilage visant à améliorer le processus de contextualisation des erreurs. Un encodage de l'ontologie adapté au traitement de flux de données RDF a été développé pour supporter les inférences de RDFS enrichis de owl : sameAs. Conjointement, un formalisme compressé de représentation des flux (PatBin) a été conçu et implanté dans la plateforme. Il se base sur la régularité des motifs des flux entrants. Enfin, un langage de requêtage a été développé à partir de ce formalisme. Il intègre une stratégie de raisonnement se basant sur la matérialisation et la réécriture de requêtes. Enfin, à partir de déductions provenant d'un d'apprentissage automatique, un outil de génération de requêtes a été implanté. Ces différentes contributions ont été évaluées sur des jeux de données concrets du domaine ainsi que sur des jeux d'essais synthétiques / With the developpement and the expansion of connected devices in every domain, several projects on stream processing have been developped. This thesis has been realized as part of the FUI Waves, a reasoning stream processing engine distributed. The use case for the developement was the processing of data streamed from a potable water distribution network, more specifically the detection of anomalies in the quality measures and their contextualisation using external data. Several contributions have been realized and integrated in different stages of the project, wih evaluations and publications witnessing their relevance. These contributions use an ontology that has been designed thanks to collaboration with domain experts working for our water data management project partner. The use of geographical data allowed to realize a profiling system aiming at improving the anomaly contextualisation process. An ontology encoding approach, adapted to RDF stream processing, has been developped to support RDFS inferences enriched with owl : sameAs. Conjointly, a compressed formalism (PatBin) has been designed to represent streams. PatBin is based on the regularity of patterns found in incoming streams. Moreover, a query language has been conceived from PatBin, namely PatBinQL. It integrates a reasoning strategy that combines both materialization and query rewritting. Finally, given deductions coming from a Waves machine learning component, a query generation tool has been developped. These diferent contributions have been evaluated on both real-world and synthetic datasets

Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-08-16T12:47:03Z No. of bitstreams: 1 Sadick.pdf: 2266912 bytes, checksum: f7c0795c47de171be894492b7a3698c6 (MD5) / Made available in DSpace on 2017-08-16T12:47:03Z (GMT). No. of bitstreams: 1 Sadick.pdf: 2266912 bytes, checksum: f7c0795c47de171be894492b7a3698c6 (MD5) Previous issue date: 2008-02-14 / The Internet has experienced a considerable increase in the use of audio and video applications, which provoke a large consumption of the resources available in the network and servers. Therefore, the monitoring and analysis of those resources becomes an essential task in order to enhance the service delivered to users. This work depicts a monitoring module implemented in a video server architecture, which is used to track the transmission of some popular video formats. Our experiments have demonstrated that one of the formats delivers a performance considerably better than the other, regarding the bandwidth allocated to each user session, what only reassures the importance of having such a monitoring module available in a server architecture. / A Internet tem experimentado, nos últimos anos, um considerável aumento no uso de aplicações de áudio e vídeo, as quais promovem um acentuado consumo dos recursos disponíveis na rede e nos servidores. Desta forma, torna-se essencial o monitoramento e análise da utilização desses recursos, a fim de melhorar os serviços prestados aos usuários. Este trabalho descreve um módulo de monitoramento implementado em um servidor de vídeo, o qual é utilizado para acompanhar a transmissão de diferentes formatos populares de vídeo via streaming. Observou-se, por meio de experimentos, que um dos formatos apresenta um desempenho consideravelmente melhor que o outro, no que se refere à largura de banda alocada a cada sessão de usuário, o que corrobora a importância de módulos de monitoramento, tal como o desenvolvido nesta dissertação.

Not long ago streaming video over the Internet included only short clips of low quality video. Now the possibilities seem endless as professional productions are made available in high definition. This explosion of growth is the result of several factors, such as increasing network performance, advancements in video encoding technology, improvements to video streaming techniques, and a growing number of devices capable of handling video. However, despite the improvements to Internet video streaming this paradigm is still evolving. HTTP adaptive streaming involves encoding a video at multiple quality levels then dividing those quality levels into small chunks. The player can then determine which quality level to retrieve the next chunk from in order to optimize video playback when considering the underlying network conditions. This thesis first presents an experimental framework that allows for adaptive streaming players to be analyzed and evaluated. Evaluation is beneficial because there are several concerns with the adaptive video streaming ecosystem such as achieving a high video playback quality while also ensuring stable playback quality. The primary contribution of this thesis is the evaluation of prefetching by a proxy server as a means to improve streaming performance. This work considers an implementation of a proxy server that is functional with the extremely popular Netflix streaming service, and it is evaluated using two Netflix players. The results show its potential to improve video streaming performance in several scenarios. It effectively increases the buffer capacity of the player as chunks can be prefetched in advance of the player's request then stored on the proxy to be quickly delivered once requested. This allows for degradation in network conditions to be hidden from the player while the proxy serves prefetched data, preventing a reduction to the video quality as a result of an overreaction by the player. Further, the proxy can reduce the impact of the bottleneck in the network, achieving higher throughput by utilizing parallel connections to the server.

Nowadays, there are various electrokinetic phenomena which are utilized in a wide range of applications, ranging from microfluidics and colloid and interface science to electrochemistry. However, even after 200 years of research on electrokinetic phenomena, there are still open questions with respect to fundamental understanding. The focus of this thesis is on three different phenomena, i.e., streaming potential, streaming current and electroosmosis. Hence, the thesis is divided in two parts: The first part focuses on the applicability of the classical Helmholtz-Smoluchowski theory on streaming potential and streaming current measurements of poly(methyl methacrylate) (PMMA) wafers, to infer the zeta potential of this substrate in contact with liquids of defined pH and ionic strength. In detail, we perform electrical impedance spectroscopy measurements to infer the electrical resistance in a PMMA microchannel and derive novel correlations for the electrokinetic characterization of the substrate. We conclude that convection can have a significant impact on the electrical double layer configuration which is reflected by changes in the surfaces conductivity. The second part of the thesis is concerned with electroosmotic flows in porous substrates where we develop a phenomenological correlation which is based on dimensional reasoning. A large set of experiments is carried out using a relatively simple and cost-effective setup including different sintered packed beds of borosilicate microspheres. A centre-of-mass model of the experimental setup allows for the interpretation of various effects. Streaming current measurements result in a correlation for the zeta potential of borosilicate depending on ionic strength and pH of the liquid. Finally, a quantitative expression for electroosmotic flow in packed beds of granular material is derived from the experiments. This correlation can be employed with other materials as well. / Thesis (Master, Chemical Engineering) -- Queen's University, 2014-06-11 10:58:11.557