Orientador: Jose de Alencar Simoni / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-14T14:06:44Z (GMT). No. of bitstreams: 1 Carvalho_SergioCandidode_M.pdf: 7891405 bytes, checksum: 82421be414263c1fb55bbc8ad39f0be9 (MD5) Previous issue date: 2009 / Resumo: Neste trabalho foram verificados os efeitos da aplicação de seis vídeos experimentais para o ensino de química, na escola Fundação Educacional Guaçuana (Mogi Guaçu- SP). Os filmes mostram experimentos reais, com ênfase em determinações quantitativas, manipulação correta de reagentes e uso de instrumentação simples. Para se estudar o real impacto da aplicação dos filmes no processo ensino-aprendizagem foi utilizada a técnica do grupo controle. As turmas foram divididas em dois grupos. No grupo definido como A, houve apenas uma exposição oral do conteúdo na forma tradicional, lousa e giz, e no grupo B, além de exposição oral do assunto, o filme também foi apresentado. Os resultados da aplicação foram verificados utilizando-se dois questionários: um denominado qualitativo, para verificar a motivação, a compreensão, a curiosidade, o esclarecimento de dúvidas, o interesse e o entendimento do assunto e um quantitativo, em que os alunos responderam a itens envolvendo o conteúdo químico abordado. Os resultados obtidos revelaram-se bastante positivos, tanto no questionário qualitativo quanto no quantitativo, com a aplicação dos vídeos. No questionário qualitativo, alguns exemplos de depoimentos dos alunos corroboram a assertiva anterior: "Com o vídeo ficou mais fácil entender a matéria e isso fez com que a aula ficasse mais interessante", "O vídeo ajudou, fez entender melhor e deixou a aula mais interessante. Poderia ser sempre assim." O questionário quantitativo mostrou, em linhas gerais, um melhor desempenho dos alunos que assistiram aos vídeos em comparação com aqueles que tiveram apenas a exposição teórica do assunto, englobando, também aí , a apresentação do experimento do vídeo em forma de esquema na lousa. / Abstract: In this work the effects of the application of six movies of chemical experiments in the learning process were verified. The study was conducted at the Fundação Educacional Guaçuana (Mogí Guaçu-SP- Brazil) school. The movies show real experiments with emphasis in quantitative determinations, correct manipulation of reagents and uses of simple instrumentation. In order to study the impact of the applications in the learning process, the group technique was used. Two groups were used: group A (control) where the subjects were presented in traditional form (blackboard and chalk), and group B (experimental) where the oral subject explanations were followed by the movie presentations. The results were checked by application of two questionnaires: one (qualitative) to verify the motivation, the subject understanding, the curiosity stimulation and the interest and another (quantitative) where students answered questions related to the subject. The positive results of the movie applications were verified in the both questionnaires. In the qualitative questionnaire, some examples of the students' depositions corroborated the previous assertive: "With the video it was easier to understand the matter and turned more interesting the class", "The video helped me, it make the subject easier to understand and turned the class more interesting. It could always be like this". The quantitative questionnaire showed, in general lines, better marks for the students who attended the videos in comparison with those that just had the theoretical subject presentation and the experiment was outlined in the blackboard. / Mestrado / Físico-Química / Mestre em Química

Streaming multimedia content over the IP-network is poised to be the dominant Internet traffic for the coming decade, predicted to account for more than 91% of all consumer traffic in the coming years. Streaming multimedia content ranges from Internet television (IPTV), video on demand (VoD), peer-to-peer streaming, and 3D television over IP to name a few. Widespread acceptance, growth, and subscriber retention are contingent upon network providers assuring superior Quality of Experience (QoE) on top of todays Internet. This work presents the first empirical understanding of Internet’s video-QoE capabilities, and tools and protocols to efficiently infer and improve them. To infer video-QoE at arbitrary nodes in the Internet, we design and implement MintMOS: a lightweight, real-time, noreference framework for capturing perceptual quality. We demonstrate that MintMOS’s projections closely match with subjective surveys in accessing perceptual quality. We use MintMOS to characterize Internet video-QoE both at the link level and end-to-end path level. As an input to our study, we use extensive measurements from a large number of Internet paths obtained from various measurement overlays deployed using PlanetLab. Link level degradations of intra– and inter–ISP Internet links are studied to create an empirical understanding of their shortcomings and ways to overcome them. Our studies show that intra–ISP links are often poorly engineered compared to peering links, and that iii degradations are induced due to transient network load imbalance within an ISP. Initial results also indicate that overlay networks could be a promising way to avoid such ISPs in times of degradations. A large number of end-to-end Internet paths are probed and we measure delay, jitter, and loss rates. The measurement data is analyzed offline to identify ways to enable a source to select alternate paths in an overlay network to improve video-QoE, without the need for background monitoring or apriori knowledge of path characteristics. We establish that for any unstructured overlay of N nodes, it is sufficient to reroute key frames using a random subset of k nodes in the overlay, where k is bounded by O(lnN). We analyze various properties of such random subsets to derive simple, scalable, and an efficient path selection strategy that results in a k-fold increase in path options for any source-destination pair; options that consistently outperform Internet path selection. Finally, we design a prototype called source initiated frame restoration (SIFR) that employs random subsets to derive alternate paths and demonstrate its effectiveness in improving Internet video-QoE.

Multimedia services are the killer applications on next generation convergent networks. Video contents are the most resource consuming part of a multimedia flux. Video transmission, video multicast and video conferencing services are the most popular types of video communication with increasing difficulty levels. Four main parts of the distributed cross-layer scalable multimedia services over next generation convergent networks are considered in this research work, both from the architecture and performance point of views. Firstly, we evaluate the performance of scalable multimedia transmissions over an overlay network. For that, we evaluate the performance of scalable video end-to-end transmissions over EvalSVC. It is capable of evaluating the end-to-end transmission of SVC bit-streams. The output results are both objective and subjective metrics of the video transmission. Through the interfaces with real networks and an overlay simulation platform, the transmission performance of different types of SVC scalability and AVC bit-streams on a bottle-neck and an overlay network will be evaluated. This evaluation is new because it is conducted on the end-to-end transmission of SVC contents and not on the coding performance. Next, we will study the multicast mechanism for multimedia content over an overlay network in the following part of this PhD thesis. Secondly, we tackle the problems of the distributed cross-layer scalable multimedia multicast over the next generation convergent networks. For that, we propose a new application-network cross layer multi-variable cost function for application layer multicast of multimedia delivery over convergent networks. It optimizes the variable requirements and available resources from both the application and the network layers. It can dynamically update the available resources required for reaching a particular node on the ALM's media distribution tree. Mathematical derivation and theoretical analysis have been provided for the newly proposed cost function so that it can be applied in more general cases of different contexts. An evaluation platform of an overlay network built over a convergent underlay network comprised of a simulated Internet topology and a real 4G mobile WiMAX IEEE802.16e wireless network is constructed. If multicast is the one-to-many mechanism to distribute the multimedia content, a deeper study on the many-to-many mechanism will be done in the next part of the thesis through a new architecture for video conferencing services. Thirdly, we study the distributed cross-layer scalable video conferencing services over the overlay network. For that, an enriched human perception-based distributed architecture for scalable video conferencing services is proposed with theoretical models and performance analysis. Rich theoretical models of the three different architectures: the proposed perception-based distributed architecture, the conventional centralized architecture and perception-based centralized architecture have been constructed by using queuing theory to reflect the traffic generated, transmitted and processed at the perception-based distributed leaders, the perception-based centralized top leader, and the centralized server. The performance of these three different architectures has been considered in 4 different aspects. While the distributed architecture is better than the centralized architecture for a scalable multimedia conferencing service, it brings many problems to users who are using a wireless network to participate into the conferencing service. A special solution should be found out for mobile users in the next part of the thesis. Lastly, the distributed cross-layer scalable video conferencing services over the next generation convergent network is enabled. For that, an IMS-based distributed multimedia conferencing services for Next Generation Convergent Networks is proposed. [...]

Multi-parti de conférence multimédia est le type le plus compliqué de la communication mais aussi le service principalement utilisé sur Internet. Il est aussi la killer application sur les réseaux 4G. Dans cette recherche, nous nous concentrons sur trois parties principales du service de téléconférence: L'architecture de distribution de médias, le codage vidéo, ainsi que l'intégration du service dans les infrastructures sans fil 4G. Nous proposons un algorithme d'application nouvelle couche de multidiffusion utilisant une architecture de services distribués. L'algorithme proposé estime que les limites de la perception humaine, tout en participant à une conférence vidéo afin de minimiser le trafic qui n'est pas nécessaire pour la session de communication. Riche des modèles théoriques de la perception basée proposé architecture distribuée, l'architecture traditionnelle centralisée et basée sur la perception architecture centralisée ont été construits en utilisant la théorie d'attente afin de refléter le trafic généré, transmises et traitées à l'pairs distribués, les dirigeants et le serveur centralisé. La performance des architectures a été pris en compte dans les différents aspects de la durée totale d'attente, le retard de point à point et le taux de service requis pour le débit total. Ces résultats aident le lecteur à avoir une vue globale des performances de la proposition dans une comparaison équitable avec les méthodes conventionnelles. Pour construire l'arbre de distribution des médias pour l'architecture distribuée, une fonction de coût nouvelle application-aware multi-variable est proposée. Il tient compte des besoins variables des applications et des mises à jour dynamiquement les ressources disponibles nécessaires pour parvenir à un nœud particulier sur l'arbre de distribution de l'ALM. Codage vidéo scalable est utilisé comme le principal multi-couche codec à la conférence. Afin d'évaluer la performance de la fonction de coût multi-variable nouvellement proposées dans une application dynamique et avancé environnement réseau sans fil, codage vidéo scalable (SVC) des transmissions sur un réseau overlay ALM construite sur un réseau sous-4G/WiMAX réelles ont été utilisées. Nous avons développé EvalSVC et l'utiliser comme plate-forme principale pour évaluer la fonction de coût proposé. Comme un problème commun, l'architecture distribuée nécessite que les pairs contribuent une partie de leur bande passante et capacité de calcul afin de maintenir la superposition mutuelle inter-connexion. Cette exigence se développe en un grave problème pour les utilisateurs mobiles et l'infrastructure sans fil, comme la ressource radio de ce réseau est extrêmement coûteux, et est l'une des raisons pour lesquelles l'architecture distribuée n'a pas été largement appliquée dans la prochaine génération (4G) des réseaux. C'est aussi la raison principale pour laquelle les services multimédias tels que vidéo-conférence doivent s'appuyer sur une architecture centralisée coûteuse construite sur un des contrôleurs des médias coûteux fonction des ressources (CRFM), via l'IMS (IP Multimedia Subsystem). Ce travail de recherche propose une nouvelle architecture distribuée utilisant la capacité de renseignement et extra, actuellement disponibles sur le LTE et stations de base WiMAX de réduire le besoin des débits que chacun a à fournir par les pairs afin de maintenir le réseau overlay. Cette réduction permet d'économiser des ressources précieuses et de radio permet une architecture distribuée pour fournir des services de visioconférence sur les réseaux 4G, avec tous les avantages d'une architecture distribuée, comme la flexibilité, l'évolutivité, les petits retards et à moindre coût. De plus, cela peut être mis en œuvre avec une modification minimale de la plate-forme standardisée IMS et les infrastructures 4G, économisant ainsi les opérateurs et les fournisseurs de services d'investissements excessifs. [...] / Multimedia services are the killer applications on next generation convergent networks. Video contents are the most resource consuming part of a multimedia flux. Video transmission, video multicast and video conferencing services are the most popular types of video communication with increasing difficulty levels. Four main parts of the distributed cross-layer scalable multimedia services over next generation convergent networks are considered in this research work, both from the architecture and performance point of views. Firstly, we evaluate the performance of scalable multimedia transmissions over an overlay network. For that, we evaluate the performance of scalable video end-to-end transmissions over EvalSVC. It is capable of evaluating the end-to-end transmission of SVC bit-streams. The output results are both objective and subjective metrics of the video transmission. Through the interfaces with real networks and an overlay simulation platform, the transmission performance of different types of SVC scalability and AVC bit-streams on a bottle-neck and an overlay network will be evaluated. This evaluation is new because it is conducted on the end-to-end transmission of SVC contents and not on the coding performance. Next, we will study the multicast mechanism for multimedia content over an overlay network in the following part of this PhD thesis. Secondly, we tackle the problems of the distributed cross-layer scalable multimedia multicast over the next generation convergent networks. For that, we propose a new application-network cross layer multi-variable cost function for application layer multicast of multimedia delivery over convergent networks. It optimizes the variable requirements and available resources from both the application and the network layers. It can dynamically update the available resources required for reaching a particular node on the ALM's media distribution tree. Mathematical derivation and theoretical analysis have been provided for the newly proposed cost function so that it can be applied in more general cases of different contexts. An evaluation platform of an overlay network built over a convergent underlay network comprised of a simulated Internet topology and a real 4G mobile WiMAX IEEE802.16e wireless network is constructed. If multicast is the one-to-many mechanism to distribute the multimedia content, a deeper study on the many-to-many mechanism will be done in the next part of the thesis through a new architecture for video conferencing services. Thirdly, we study the distributed cross-layer scalable video conferencing services over the overlay network. For that, an enriched human perception-based distributed architecture for scalable video conferencing services is proposed with theoretical models and performance analysis. Rich theoretical models of the three different architectures: the proposed perception-based distributed architecture, the conventional centralized architecture and perception-based centralized architecture have been constructed by using queuing theory to reflect the traffic generated, transmitted and processed at the perception-based distributed leaders, the perception-based centralized top leader, and the centralized server. The performance of these three different architectures has been considered in 4 different aspects. While the distributed architecture is better than the centralized architecture for a scalable multimedia conferencing service, it brings many problems to users who are using a wireless network to participate into the conferencing service. A special solution should be found out for mobile users in the next part of the thesis. Lastly, the distributed cross-layer scalable video conferencing services over the next generation convergent network is enabled. For that, an IMS-based distributed multimedia conferencing services for Next Generation Convergent Networks is proposed. [...]