The multimedia domain is undergoing a rapid development phase with transition in audio, image, and video systems such as VoIP, Telepresence, Live/On-Demand Internet Streaming, SecondLife, and many more. In such a situation, the analysis of multimedia systems, like retrieval, quality evaluation, enhancement, summarization, and re-targeting applications, from various context is becoming critical. Current methods for solving the above-mentioned analysis problems do not consider the existence of humans and their affective characteristics in the design methodology. This contradicts the fact that most of the digital media is consumed only by the human end-users. We believe incorporating human feedback during the design and adaptation stage is key to the building process of multimedia systems. In this regard, we observe that affect is an important indicator of human perception and experience. This can be exploited in various ways for designing effective systems that will adapt more closely to the human response. We advocate an affect-based modeling approach for solving multimedia analysis problems by exploring new directions. In this dissertation, we select two representative multimedia analysis problems, e.g. Quality-of-Experience (QoE) evaluation and Image Enhancement in order to derive solutions based on affect-based modeling techniques. We formulate specific hypothesis for them by correlating system parameters to user's affective response, and investigate their roles under varying conditions for each respective scenario. We conducted extensive user studies based on human-to-human interaction through an audio conferencing system.We also conducted user studies based on affective enhancement of images and evaluated the effectiveness of our proposed approaches. Moving forward, multimedia systems will become more media-rich, interactive, and sophisticated and therefore effective solutions for quality, retrieval, and enhancement will be more challenging. Our work thus represents an important step towards the application of affect-based modeling techniques for the future generation of multimedia systems.

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Video streaming applications over best-effort networks, such as the Internet, have become very popular among Internet users. Watching live sports and news, renting movies, watching clips online, making video calls, and participating in videoconferences are typical video applications that millions of people use daily. One of the most challenging aspects of video communication is the proper transmission of video in various network bandwidth conditions. Currently, various devices with different processing powers and various connection speeds (2G, 3G, Wi-Fi, and LTE) are used to access video over the Internet, which offers best-effort services only. Skype, ooVoo, Yahoo Messenger, and Zoom are some well-known applications employed on a daily basis by people throughout the world; however, best-effort networks are characterized by dynamic and unpredictable changes in the available bandwidth, which adversely affect the quality of the video. For the average consumer, there is no guarantee of receiving an exact amount of bandwidth for sending or receiving video data. Therefore, the video delivery system must use a bandwidth adaptation mechanism to deliver video content properly. Otherwise, bandwidth variations will lead to degradation in video quality or, in the worst case, disrupt the entire service. This is especially problematic for videoconferencing (VC) because of the bulkiness of the video, the stringent bandwidth demands, and the delay constraints. Furthermore, for business grade VC, which uses high definition videoconferencing (HDVC), user expectations regarding video quality are much higher than they are for ordinary VC. To manage network fluctuations and handle the video traffic, two major components in the system should be improved: the video encoder and the congestion control. The video encoder is responsible for compressing raw video captured by a camera and generating a bitstream. In addition to the efficiency of the encoder and compression speed, its output flow is also important. Though the nature of video content may make it impossible to generate a constant bitstream for a long period of time, the encoder must generate a flow around the given bitrate. While the encoder generates the video traffic around the given bitrate, congestion management plays a key role in determining the current available bandwidth. This can be done by analyzing the statistics of the sent/received packets, applying mathematical models, updating parameters, and informing the encoder. The performance of the whole system is related to the in-line collaboration of the encoder and the congestion management, in which the congestion control system detects and calculates the available bandwidth for a specific period of time, preferably per incoming packet, and informs rate control (RC) to adapt its bitrate in a reasonable time frame, so that the network oscillations do not affect the perceived quality on the decoder side and do not impose adverse effects on the video session. To address these problems, this thesis proposes a collaborative management architecture that monitors the network situation and manages the encoded video rate. The goal of this architecture is twofold: First, it aims to monitor the available network bandwidth, to predict network behavior and to pass that information to the encoder. So encoder can encode a suitable video bitrate. Second, by using a smart rate controller, it aims for an optimal adaptation of the encoder output bitrate to the bitrate determined by congestion control. Merging RC operations and network congestion management, to provide a reliable infrastructure for HDVC over the Internet, represents a unique approach. The primary motivation behind this project is that by applying videoconference features, which are explained in the rate controller and congestion management chapter, the HDVC application becomes feasible and reliable for the business grade application even in the best-effort networks such as the Internet.

Un service Web est un moyen d'offrir des fonctionnalités sur un réseau en utilisant des normes ouvertes pour la description et l'invocation. Les services Web représentent une réalisation importante de l'Architecture Orientée Service (AOS), à l'aide de qui, les applications peuvent être développées rapidement avec un coût bas par couplage faible les services sur un réseau. Cela nécessite la découverte et la composition des ensembles de services interopérables, selon certaines exigences fonctionnelles et non fonctionnelles. Les services Web confrontent de nombreux défis quant à leur découverte et sélection, en raison de plusieurs facteurs tels que: le nombre important de services, le manque de registres publics capables d'offrir des mécanismes efficaces de récupération de service, de leur nature dynamique qui impose divers aspects de QoS tels que la disponibilité, le temps de réponse, etc, et le manque de sémantique dans leurs descriptions d'interface. Dans cette thèse, nous avons deux objectifs principaux. Notre premier objectif est de faciliter la sélection des services Web et d'assurer la continuité du service dans des compositions de services Web. Par conséquent, nous proposons une approche basée sur l'analyse formelle de concepts (AFC) pour classer les services Web dans un premier temps par mots clés, puis par les valeurs de similarité entre leurs opérations. Cette classification est représentée comme un treillis de concepts qui révèle les relations entre les services, ce qui facilite la sélection d'un service nécessaire ainsi que l'identification des potentiels sauvegardes (substitutions en cas de panne). Notre deuxième objectif est de guider l'utilisateur en effectuant une sélection optimisée basée sur des plusieurs critères. Nous définissons un descripteur pour l'utilisateur qui spécifie des exigences fonctionnelles et non fonctionnelles. Dans ce descripteur, les propriétés fonctionnelles sont spécifiées comme un ensemble de mots-clés. Les propriétés non fonctionnelles représentent les niveaux attendus de QoS (bon, mauvais, moyen, ..) ainsi que la composition de services exprimée en tant que liens entre les propriétés fonctionnelles spécifiées. Afin d'atteindre cet objectif, nous proposons une approche basée sur l'analyse relationnelle de concepts (ARC) qui classifie les services Web en treillis de concepts similaires à la AFC, mais enrichis avec les propriétés non-fonctionnelles. Nous proposons également un mécanisme permettant d'interroger le concept de treillis résultant basée sur RCA, selon les exigences spécifiées dans le descripteur. Nous avons validé notre proposition en utilisant des services Web réels extraits de Service-Finder et Seekda (des moteurs de recherche de services Web). Pour l'approche basée sur la AFC, nous avons récupéré un total de 145 services Web que nous avons classés en fonction de leur fonctionnalité. Nous avons montré comment sélectionner efficacement un service offrant les fonctionnalités requises et la manière d'identifier ses sauvegardes. Pour l'approche basée sur RCA, nous avons récupéré 901 services Web que nous avons classés selon leur niveau de QoS et de composabilité. Nous avons vérifié que cette approche permet une sélection efficace des services correspondant aux exigences fonctionnelles et non fonctionnelles spécifiées. / A Web service is a way of offering functionality over a network using open standards for description and invocation. Web services represent an important realization of Service-Oriented Architectures (SOA), using which, applications can be developed rapidly with a low cost by loosely coupling services over a network. This necessitates discovering and composing sets of interoperable services, according to some functional and non-functional requirements.Web services face many challenges regarding their discovery and selection, due to several factors like: the fairly large number of services, the lack of public registries capable of offering efficient service retrieval mechanisms, their dynamic nature which imposes various QoS aspects such as availability, response time, etc., and the lack of semantics in their interface descriptions.In this thesis, we have two main objectives. Our first objective is to facilitate Web service selection and assure service continuity in Web service compositions. Therefore, we propose an approach based on Formal Concept Analysis (FCA) to classify Web services first by keywords then by similarity values between their operations. This classification is represented as a concept lattice that reveals the relations between the services, which facilitates the selection of a needed service as well as the identification of its potential backups (substitution in case of failure).Our second objective is to guide the user towards performing an optimized multi-criteria based selection. We define a user requirements descriptor that specifies the needed functional and non-functional properties. Inside this descriptor, functional properties are specified as a set of keywords. Non-functional properties represent the expected QoS levels (good, bad, medium, ..) as well as the composition of services expressed as links between the specified functional properties. In order to meet this objective, we propose an approach based on Relational Concept Analysis (RCA) that classifies Web services into concept lattices similar to FCA, but enriched with the non-functional properties. We also propose a mechanism to query the resulting RCA-based concept lattices, according to the requirements specified in the descriptor.We validated our proposition using real Web services retrieved from Service-Finder and Seekda Web service search engines. For the FCA-based approach, we retrieved a total of 145 Web services that we classified by their functionality. We showed how to select efficiently a service offering the required functionality and how to identify its backups.For the RCA-based approach, we retrieved 901 Web services that we classified by their QoS and composability levels. We verified that the approach allows an efficient selection of services corresponding to the specified functional and non-functional requirements.

This thesis is devoted to service quality management in the field of hotel services. It focuses mainly on an analysis of service quality and an evaluation of guest satisfaction in a selected five-star hotel in Prague. The purpose of this thesis is to find orientation in a system through which hotel investigates guest satisfaction and find its opportunities while generating useful data that will serve the hotel management. The theoretical part provides an outline of the basic methods of quality management and focuses on building a customer relationship. The practical part contains evaluation of standards and tools used at Boscolo Prague hotel along with an analysis of service quality and guest satisfaction. Attention is also paid to the effectiveness of newly introduced measures that should increase guest satisfaction. The final section is engaged in evaluating the outcomes of the analysis and in recommending possible improvements.

Ce travail de thèse présente trois contributions qui portent sur le routage et la fourniture de qualité de service dans les réseaux maillés sans fil basés sur IEEE 802.11. La première contribution définit une métrique de routage qui permet de sélectionner les chemins empruntant des liens avec de bonnes performances exprimées en termes d’interférences physiques (qui causent des pertes), d’interférences logiques (qui causent des délais) et de capacité. L’évaluation de cette métrique par rapport aux principales métriques de la littérature scientifique montre une amélioration des performances du réseau. La deuxième contribution concerne l’amélioration du mécanisme de maintenance de route le plus souvent utilisé par les protocoles de routage réactifs. Ce mécanisme considère qu'une route est coupée si l'un de ses liens observe plusieurs échecs successifs de retransmission. Nos études montrent que ces échecs sont assez souvent dûs à de problèmes transitoires sur les liens (bruit, interférence etc.). Nous avons donc proposé des algorithmes de maintenance de route qui appréhendent mieux les problèmes ponctuels ou soutenus sur les liens ce qui permet de prendre une décision cohérente et réfléchie quant à la coupure d’un lien (et donc d'une route). Les études de performances montrent une amélioration conséquente des performances globales du réseau. La dernière contribution propose un cadre pour la fourniture de la Qualité de Service (garantie de bande passante) dans les réseaux maillés multi-interfaces, multi-canaux. Ce cadre intègre un protocole de routage réactif couplé à un mécanisme de contrôle d'admission et de partage de charge. Ces derniers exploitent la diversité des liens entre nœuds voisins afin d’améliorer le taux d’admission des flux avec garantie de bande passante / This thesis presents three contributions in the area of routing and Quality of Service for IEEE 802.11-based Wireless Mesh Networks. The first contribution defines a routing metric for the selection of route by taking into consideration the performance of wireless links in terms of physical interference (which causes packet losses), logical interference (which causes delay) and the capacity of the links. The performance evaluation of the proposed metric compared to the popular existing metrics shows an improvement in the performance of the network. The second contribution improves the route maintenance mechanism most often used by reactive routing protocols. The existing mechanism considers a route as broken if any of the links in the route experiences multiple successive transmission failures. Our study shows that the transmission failures are often caused by transient problems on the wireless link (noise, interference etc). We propose a novel mechanism of route maintenance which distinguishes between links with temporary or transient transmission problems compared to those with sustained problems in order to make a coherent decision about link breakage (and consequently route breakage). The performance evaluation shows a substantial improvement in the performance of the network. The final contribution proposes a framework for providing Quality of Service (bandwidth guarantee) in multi-radio multi-channel wireless mesh networks. The framework integrates a reactive routing protocol coupled with an admission control mechanism and load balancing. The framework exploits link diversity between neighboring nodes to improve the flow admission ratio with bandwidth guarantees

Esta tese de doutorado apresenta a investigação de alternativas para melhorar o desempenho de ambientes Web, avaliando o impacto da utilização de mecanismos de diferenciação de serviços em todos os pontos do sistema. Foram criados e modelados no OPNET Modeler cenários com diferentes configurações voltadas tanto para a diferenciação de serviços, quanto para o congestionamento da rede. Foi implementado um servidor cache com suporte à diferenciação de serviços (cache CDF), que constitui uma contribuição dentro deste trabalho, complementando o cenário de diferenciação de serviços de forma positiva, assegurando que os ganhos obtidos em outras etapas do sistema não sejam perdidos no momento da utilização do cache. Os principais resultados obtidos mostram que a diferenciação de serviços introduzida de forma isolada em partes do sistema, pode não gerar os ganhos de desempenho desejados. Todos os equipamentos considerados nos cenários propostos possuem características reais e os modelos utilizados no OPNET foram avaliados e validados pelos seus fabricantes. Assim, os modelos que implementam os cenários considerados constituem também uma contribuição importante deste trabalho, uma vez que o estudo apresentado não se restringe a uma modelagem teórica, ao contrário, aborda aspectos bem próximos da realidade, constituindo um possível suporte de gerenciamento de sistemas Web / This PhD thesis presents the investigation of alternatives to improve the performance of Web environments by evaluating the impact of using differentiated service mechanisms in all points of the system. Several scenarios were created and modeled in the OPNET Modeler, with different configurations of both differentiated services and network overloading. A special cache server supporting differentiated services (CDF cache) was proposed and included in the model, comprising one of the major contributions of this work once it positively complements the differentiated service scenario, making that the gains obtained with other stages of the system do not be spoiled when using the cache. The main results obtained show that the adoption of differentiated services in isolated parts of the system cannot generate the expected performance gains. The features of all the equipments considered in the several scenarios defined in this work are very close to the reality and the models used in the OPNET were evaluated and validated by the companies that produce those equipments. Thus, the models that implement the scenarios considered in this work also comprises an important contribution of this thesis, once the study presented is not just a theoretical modeling exercise but, conversely, it approaches aspects very close to the reality, comprising a possible Web system management support

Este trabalho propõe mecanismos de diferenciação de serviços para servidores Web, visando a melhorar o desempenho desses sistemas quando são consideradas as características das requisições Web nas políticas de atendimento. Optou-se por adotar o contexto do comércio eletrônico para a realização das pesquisas, uma vez que esse ambiente é um dos mais impactados negativamente quando há um comportamento inadequado do servidor em situações de sobrecarga. Para isso, foi realizada uma investigação das características das requisições Web típicas do e-commerce, para que tais características pudessem ser usadas como diretrizes para os mecanismos e melhorar o desempenho dos servidores. Em seguida, foram propostos um modelo de carga de trabalho e um modelo de simulação para a realização dos experimentos. Com isso, foi possível avaliar os resultados obtidos com a inserção dos diversos mecanismos no Servidor Web com Diferenciação de Serviços (SWDS), um modelo de servidor cuja arquitetura o torna capaz de fornecer serviços diferenciados a seus usuários e aplicações. Foram propostos novos mecanismos de escalonamento de requisições bem como novos mecanismos de controle de admissão. Diversas simulações foram realizadas e os resultados obtidos mostram que a exploração das características das requisições Web, além de ser fundamental para um bom entendimento do comportamento do servidor, possibilita a melhoria de desempenho do sistema / This work proposes differentiated services mechanisms for Web servers, aiming at improving their performance when the features of Web requests are considered. The electronic commerce (e-commerce) context was adopted to develop the researches once this environment is one of the most negatively influenced when there is an inadequate behavior of the server under overload situations. Thus, it was realized an investigation on the features of ecommerce Web requests, so that these features could be used both as guidelines for the mechanisms and to improve the performance of the servers. Afterwards, a workload model and a simulation model were proposed to implement the experiments. Thus, it was possible to evaluate the results obtained with the insertion of several mechanisms in the Web Server with Differentiated Services (WSDS), a server model with an architecture that makes it capable of supplying differentiated services to its users and applications. New request scheduling mechanisms were proposed as well as new mechanisms for admission control. Several simulations were realized and the obtained results show that the exploration of the Web request features, besides being fundamental for a good understanding of the server behavior, makes possible to improve the system performance

Actualmente, la industria de restaurantes, en el Perú, se ha visto en la necesidad de adaptarse a las nuevas tendencias de los consumidores correspondientes a la alimentación saludable y estilos de vida acelerados. Por ello, se observa la aparición y expansión progresiva de nuevos formatos en Lima, como los Fast Good, que atienden dichas necesidades de manera específica. Por lo tanto, el objetivo del presente estudio es evaluar, a través del modelo DINESERV, la percepción de los comensales sobre las dimensiones de la calidad del servicio, el producto y precio, que derivan en la satisfacción final de los clientes, lo cual puede ser favorable o no, dependiendo de la gestión de dichos atributos por parte de los administradores y fundadores del nuevo formato. / Nowadays, Restaurant Industry in Peru has found it necessary to adapt to new consumers’ trends regarding healthier eating and faster lifestyles. Therefore, new business models such as Fast Good have progressively appeared and expanded in order to specially fulfill those needs. Therefore, the objective of this investigation is to evaluate, through the and DINESERV model, the perception of the dimensions of service quality, product and price, that result in customer satisfaction, which may be favorable or not, depending on how business creators implement those attributes in this new formats. / Trabajo de investigación

Master thesis is dealing with issues and problems of packet queue management in high speed packet networks. Design implementation is made in VHDL hardware description language. In theoretical part of thesis are explained different types of mechanism used for providing quality of service in communication networks. Furthermore the brief description o VHDL, FPGA and framework Netcope Development Kit is a piece of theoretical part as well. The outcome of practical part contains a design, limiting packet queues based on Tocken Bucket mechanism. Design verification was made by simulations, synthesis and real implementation on smart NIC NFB-200G2QL. All kind of verificaion results are summerized in last three chapters.