Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (p. 180-186).

Dissertation (Ph.D.) -- Worcester Polytechnic Institute. / Keywords: streaming media; streaming transport protocol; active queue management (AQM); Internet congestion control. Includes bibliographical references (p. 236-248).

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: continuous queries; moving objects. Includes bibliographical references (p.102-110).

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 137-144).

Thesis (M.S.)--University of North Texas, May, 2007. / Title from title page display. Includes bibliographical references.

Τα τελευταία χρόνια είδαν την άνθιση διαδικτυακών εφαρμογών και υπηρεσιών διαμοιρασμού αντικειμένων πολυμέσων. Την τιμητική τους είχαν τα αντικείμενα οπτικοακουστικού περιεχομένου (video), δίνοντας πρωταγωνιστικό ρόλο στην ανάπτυξη συστημάτων διαμοιρασμού βίντεο. Μάλιστα, ανταποκρινόμενα στην δυνατότητα των χρηστών για επιλογή περιεχομένου, που παρείχαν η ραγδαία αύξηση της χρήσης του διαδικτύου και η βελτίωση των υποδομών αυτού, έγιναν ιδιαίτερα δημοφιλή τα συστήματα και οι υπηρεσίες διαμοιρασμού βίντεο κατόπιν ζήτησης Ωστόσο οι αυξημένες απαιτήσεις τους σε κλιμάκωση, προσαρμοστικότητα, απόδοση και ανεκτικότητα σε σφάλματα, κατέστησαν απαραίτητη την υποστήριξή τους από κατανεμημένες ή και παράλληλες αρχιτεκτονικές. Μία αρκετά υποσχόμενη προσέγγιση προς αυτή την κατεύθυνση είναι τα διομότιμα συστήματα καθώς οι ίδιοι οι χρήστες των εφαρμογών διαθέτουν ένα τεράστιο σύνολο από δικτυακούς και υπολογιστικούς πόρους. Στα συστήματα αυτά το περιεχόμενο που κατεβάζουν οι χρήστες διασπάται σε κομμάτια τα οποία ανταλλάσσονται από αυτούς ,με σκοπό την τελική επανασύνδεση και ανάκτηση του συνολικού μεγέθους των δεδομένων. Σκοπός αυτής της διπλωματικής είναι η μελέτη της αξιοποίησης του εύρους ζώνης στα πλαίσια ενός διομότιμου συστήματος διαμοιρασμού βίντεο κατόπιν ζήτησης με πολλαπλά κανάλια. Η παρατήρηση του τρόπου συμπεριφοράς των χρηστών και του συνολικού συστήματος ως προς τον πολύτιμο αυτό δικτυακό πόρο, μπορεί να αποτελέσει την βάση για την ανάπτυξη εφαρμογών με μεγαλύτερη αποδοτικότητα, πιο οικονομικών στην λειτουργία τους, και με βελτιωμένη ευελιξία. / The last year saw the flourishing of Internet applications and services sharing media objects. Their honor were the objects of audiovisual content (video), giving a leading role in the development of video sharing. Indeed, in response to users' ability to select content, provided by the rapid growth of internet usage and to improve the infrastructure of this, became very popular in the systems and services for sharing video on demand However, the increased demands on scalability, flexibility, performance and fault tolerance, made it necessary to support them or from distributed and parallel architectures. A very promising approach in this direction is the diomotima systems and the users themselves applications have a huge amount of network and computing resources. In these systems the content download users cleaved into pieces which are exchanged by them, with the final reconnection and recovery of the total size of data. The aim of this thesis is to study the utilization of bandwidth within a peer sharing system video on demand with multiple channels. The observation of how user behavior and the overall system to this valuable web resource, can provide the basis for developing applications with greater efficiency, more economical to operate, and with improved flexibility.

Dynamic Adaptive Streaming over HTTP (DASH) is a convenient approach to transfer videos in an adaptive and dynamic way to the user. Therefore, this system makes best use of the bandwidth available. In this thesis, we investigate Dynamic Adaptive Streaming over HTTP (DASH) based on data collected from the lab experiments and user’s experiments. The objectives include investigation of how three different DASH players behave at different network conditions and up to which limit the players are tolerating the disturbances. We summarized the outcome of lab experiments on DASH at different adverse conditions and checked the lab results with user quality of experience at different adverse conditions to see up to which extent the users could tolerate the disturbances in different DASH players.

Streaming multimedia over the Internet is omnipresent but still in its infancy, specifically when it comes to theadaptation based on bandwidth/throughput measurements, clients competing for limited/shared bandwidth, and thepresence of a caching infrastructure. Nowadays the streaming infrastructure is existing over-the-top (OTT).Interestingly, these services are all delivered over-the-top of the existing networking infrastructure using the HypertextTransfer Protocol (HTTP) which resulted in the standardization of MPEG Dynamic Adaptive Streaming over HTTP(DASH).Video traffic is over 80% of the total internet traffic. Since Dynamic adaptive streaming over HTTP hasemerged it has a popular technique for video streaming on the internet. DASH allows the video player to adapt thebitrate according to the network conditions. DASH streaming client receives a manifest file, downloaded the referredvideo segments over HTTP, and play them back seamlessly emulated video streaming. This introduces latency of atleast one segment duration which decreases the quality of the user experience. In order to improve users over allQuality of Experience(QoE) a large number of adaptaion schemes were introduced to DASH.With such an importance of QoE on DASH, this thesis work investigates user acceptability of different DASHplayers. These players are exposed to different network conditions and the user analysis is given for each of thestreaming dash video for each player. The results of this thesis work include the analysis of the user rating for threedifferent players (Dash.js, GPAC and Shaka). The conclusion of this thesis is given by the quality of experience of thevideo streaming by the users which concludes that the Shaka player is preferred by the users compared to the othertwo players.

Parmi les différents mécanismes physiques permettant d'actionner des échantillons liquides au sein de labopuces, l'électromouillage sur diélectrique (EWOD) s'impose peu à peu comme une solution fiable permettant de manipuler en particulier des gouttes (labopuces digitaux). Bien que des modèles énergétiques permettent d'expliquer la plupart des fonctions fluidiques élémentaires obtenues par effet EWOD, il demeure certains phénomènes hydrodynamiques en goutte dont la compréhension à l'échelle locale présente des enjeux en termes scientifiques et applicatifs. En particulier, la maîtrise des oscillations de goutte et des écoulements électrohydrodynamiques induits par des signaux électriques alternatifs (AC-EWOD) pourrait permettre l'insertion de nouvelles fonctions dans les labopuces digitaux (brassage, séparation d'espèces). Dans la thèse proposée, une configuration optimale a été retenue consistant en une goutte reposant sur deux électrodes coplanaires passivées. Un banc de caractérisation a été développé ainsi que des logiciels spécifiques dédiés à l'analyse du mouillage et des oscillations de la goutte. Une première étude permet de caractériser l'électromouillage d'une goutte en configuration d'électrodes coplanaires. En particulier, la modélisation des contraintes électriques surfaciques permet de conclure sur leurs rôles dans l'injection normale et tangentielle de quantité de mouvement. Les oscillations de la goutte et les écoulements induits sont ensuite étudiés de manière expérimentale. Suivant la géométrie des électrodes, des configurations d'écoulements axisymétriques et quadripolaires sont observées. Un modèle basé sur le concept de courant de dérive est développé ; sa résolution numérique par éléments finis permet de retrouver les configurations d'écoulement. Des applications biologiques de l'actuation EWOD en signal alternatif sont finalement proposées et discutées pour le développement de laboratoires sur puces. / Among numerous physical mechanisms enabling liquids actuation, electrowetting on dielectric (EWOD) is increasingly considered as a trustful solution enabling discrete iquid sample handling by using electrical fields. Although energetic models can explain most basic fluidic functions, some electrowetting phenomena still remain to be considered as scientific issues. So is the case for droplet oscillations and hydrodynamic flows induced by electrowetting when AC voltage is applied (AC EWOD). The understanding and mastering of these phenomena represent the objectives of this thesis. An open electrode configuration has been used in which the droplet straddles two insulated coplanar electrodes. An experimental setup and dedicated software for the measurement of droplet wetting and droplet oscillations have been developed. A first experimental and numerical study allowed us the characterization of electrowetting in the coplanar electrode configuration. The calculation of the electrical stress distribution delivers criteria which help to conclude about the involvement of tangential electrical stresses in drop convective flow. Then, droplet oscillations and induced flows are experimentally and theoretically investigated. Depending on electrode designs, axisymetrical and quadripolar flows as well can be observed. A model based on steady streaming is implemented and structure flows are numerically reproduced using finite element method. Some practical applications of this research within the framework of lab-on-chips are proposed and discussed.

The purpose of this thesis was to visualize the 1.7 billion stars released by the European Space Agency, as the second data release (DR2) of their Gaia mission, in the open source software OpenSpace with interactive framerates and also to be able to filter the data in real-time. An additional implementation goal was to streamline the data pipeline so that astronomers could use OpenSpace as a visualization tool in their research. An out-of-core rendering technique has been implemented where the data is streamed from disk during runtime. To be able to stream the data it first has to be read, sorted into an octree structure and then stored as binary files in a preprocess. The results of this report show that the entire DR2 dataset can be read from multiple files in a folder and stored as binary values in about seven hours. This step determines what values the user will be able to filter by and only has to be done once for a specific dataset. Then an octree can be created in about 5 to 60 minutes where the user can define if the stars should be filtered by any of the previously stored values. Only values used in the rendering will be stored in the octree. If the created octree can fit in the computer’s working memory then the entire octree will be loaded asynchronously on start-up otherwise only a binary file with the structure of the octree will be read during start-up while the actual star data will be streamed from disk during runtime. When the data have been loaded it is streamed to the GPU. Only stars that are visible are uploaded and the application also keeps track of which nodes that already have been uploaded to eliminate redundant updates. The inner nodes of the octree store the brightest stars in all its descendants as a level-of-detail cache that can be used when the nodes are small enough in screen space. The previous star rendering in OpenSpace has been improved by dividing the rendering phase into two passes. The first pass renders into a framebuffer object while the second pass then performs a tonemapping of the values. The rendering can be done either with billboard instancing or point splatting. The latter is generally the faster alternative. The user can also switch between using VBOs or SSBOs when updating the buffers. The latter is faster but requires OpenGL 4.3, which Apple products do not currently support. The rendering runs with interactive framerates for both flat and curved screen, such as domes/planetariums. The user can also switch dataset during render as well as render technique, buffer objects, color settings and many other properties. It is also possible to turn time on and see the stars move with their calculated space velocity, or transverse velocity if the star lacks radial velocity measurements. The calculations omits the gravitational rotation. The purpose of the thesis has been fulfilled as it is possible to fly through the entire DR2 dataset on a moderate desktop computer and filter the data in real-time. However, the main contribution of the project may be that the ground work has been laid in OpenSpace for astronomers to actually use it as a tool when visualizing their own datasets and also for continuing to explore the coming Gaia releases.