Novas arquiteturas de hardware desenvolvidas para blocos chave do padrão de codificação de vídeo ISO/IEC 14496-10 são discutidas, propostas, implementadas e validades nesta tese. Também chamado de H.264, AVC (Advanced Video Coder) ou MPEG-4 parte 10, o padrão é o estado da arte em codificação de vídeo, apresentando as mais altas taxas de compressão possíveis por um compressor de vídeo padronizado por organismos internacionais (ISO/IEC e ITU-T). O H.264 já passou por três revisões importantes: na primeira foram incluídos novos perfis, voltados para a extensão da fidelidade e aplicações profissionais, na segunda veio o suporte a escalabilidade (SVC – Scalable Video Coder). Uma terceira revisão suporta fontes de vídeo com múltiplas vistas (MVC – Multi-view Video Coder). Nesta tese são apresentadas arquiteturas para dois módulos do codificador H.264: o CABAC e o Filtro de Deblocagem (Deblocking Filter). O CABAC (Context-Adaptive Binary Arithmetic Coder) possui desafios importantes devido às dependências de dados de natureza bit-a-bit. Uma revisão das alternativas arquiteturais e uma solução específica para a codificação CABAC é apresentada nesta tese. O filtro de deblocagem também apresenta diversos desafios importantes para seu desenvolvimento e foi alvo de uma proposta arquitetural apresentada neste trabalho. Finalmente a arquitetura de uma plataforma de validação genérica para validar módulos desenvolvidos para o codificador e decodificador H.264 também é apresentada. Os módulos escolhidos estão de acordo com os demais trabalhos realizados pelo grupo de pesquisa da UFRGS, que têm por objetivo desenvolver um decodificador e um codificador completos capazes de processar vídeo digital de alta definição no formato 1080p em tempo real. / New hardware architectures developed for key blocks of the ISO/IEC 14496-10 video coding standard are discussed, proposed, implemented, and validated in this thesis. The standard is also called H.264, AVC (Advanced Video Coder) or MPEG-4 part 10, and is the state-of-the-art in video coding, presenting the highest compression ratios achievable by an internationally standardized video coder (ISO/IEC and ITU-T). The H.264 has already been revised three times: the first included new profiles for fidelity extension and professional applications. The second brought the scalability support (SVC – Scalable Video Coder). The third revision supports video sources with multiple views (MVC – Multi-view Video Coder). The present work developed high performance architectures for CABAC (Context-Adaptive Binary Arithmetic Coder), which were challenging because of the bitwise data dependencies. A through revision of the alternative architectures and a specific architectural solution for CABAC encoding are presented in this thesis. A dedicated hardware architecture for a HIGH profile Deblocking Filter is also presented, developed, validated and synthesized for two different targets: FPGA and ASIC. The validation methodology is presented and applied to three different modules of the H.264 encoder. The H.264 blocks dealt with in this thesis work complement those developed by other works in the UFRGS research group and contribute to the development of complete encoders for real-time processing of high definition digital video at 1080p.

Le besoin des applications de streaming multimédia en temps réel sur Internet ne cesse d’accroître. Dans ce contexte, les réseaux Pair-à-Pair (P2P) jouent un rôle prépondérant afin d’assurer une transmission robuste et extensible (scalable) de contenu multimédia à grand-échelle. Cependant, le déploiement des applications de streaming multimédia à travers les réseaux P2P présente plusieurs verrous. En effet, les applications de streaming vidéo nécessitent une garantie de performances temps réel en termes de : délai minimal de bout-en-bout, faible taux de perte de paquets et garantie de la bande passante. Par ailleurs, un réseau P2P est composé d’un ensemble de terminaux interconnectés à travers des réseaux hétérogènes, n’ayant pas forcément les mêmes caractéristiques requises afin d’offrir la même qualité vidéo aux clients finaux.Dans cette thèse, nous analysons différents problèmes liés au streaming en-direct (Live) ou à la demande (VoD) de la vidéo sur les réseaux P2P, et nous proposons un ensemble de mécanismes pour y remédier. / There is an increasing demand for efficient deployment of real-time multimedia streaming applications over Internet. In this context, Peer-to-Peer (P2P) networks are playing an important role for supporting robust and scalable transmission of multimedia content to large-scale and massive receivers. P2P networks consist of different heterogeneous networks and devices, which may not have symmetric characteristics to offer the same video quality to end clients. The deployment of streaming applications such as live and on-demand over P2P networks is challenging. Indeed, video streaming applications require real-time performance guarantee in terms of low end-to-end delay, low packet loss and guaranteed available bandwidth. Moreover, P2P video streaming also experiences the problems of long start-time and churn-induced instability. The situation leads to affect the viewing experience of the users in P2P networks.The aim of this thesis is to analyze these issues and to propose quality-aware mechanisms for both live and on-demand streaming over P2P networks. Our contributions in this dissertation are threefold. First, we propose a small world overlay organization mechanism allowing efficient organization of peers to reduce the end-to-end delay for live streaming applications. Second, we propose a mechanism for cooperative prefetching with differentiated chunks scheduling suitable for P2P video-on-demand (VoD) to efficiently handle seek operations while reducing the response latency and increasing the hit ratio. Finally, we present a smoothing mechanism for layered streaming in P2P networks. The mechanism aims to reduce the number of layer changes under varying network conditions while at the same time achieving a high delivery ratio.

No description available.

Voltage stability is a major concern when planning and operating electrical power systems.As demand for electric power increases, power systems are stressed more and more. TheFACTS family of components were introduced to utilize the existing grid to a higherdegree, while still maintaining system stability.This thesis investigates if the addition of another SVC to the Swedish national gridcould increase the power transfer from north to south. Placement of the SVC was basedon two different indices used to indicate weak areas of the grid; the Q-V sensitivity indexand the V CPI index.Simulations were performed with both the added SVC and regular switched shuntcompensation and the results were compared against each other. Studies were alsoperformed to investigate the effect of an SVC installed at the grid connection of a large(1000 MW) wind farm. Simulations were performed where the wind farm was modeledby either doubly fed induction generators (DFIG) or single cage induction generators.This simulation study was performed using PSSTME, based on a detailed model ofthe Nordic power system as it existed in 2007.The studies showed that adding a ±200 MVAr SVC to the Swedish national gridcould increase the power transfer by 150 MW, where an equally rated switched shuntcapacitor/reactor would result in a 100 MW increase. In these studies, the transfercapacity was limited by voltage collapse situations.However, installing the same ±200 MVAr SVC at the connection of a large windfarm showed an increase in power transfer by 1000 MW, while the switched shuntcompensation only resulted in a 500 MW increase. In the simulations that showed thegreatest increase in transfer capacity, the added wind farm was modeled by single-cageinduction generators. In this case the transfer capacity was limited by transient stabilityproblems.

Thyristor switched capacitors (TSCs) have found an ever increasing role in the operation of flexible AC transmission systems or FACTS. The ability of these static var compensators to regulate the voltage by consuming or supplying reactive power quickly is not only viable for transmission but is an effective measure for increasing power quality at a distribution level. The proposed design uses a variable number of logically switched capacitors to supply reactive generation per reactive demand. The design ensures that the capacitors are safely switched into service, reactive demand is accurately calculated, and the TSC will respond quickly to changes in demand. While providing fast and safe operation, the conceptual design is also flexible enough to allow for optimization of the TSC to meet the demands of specific loads.

Poussé par la demande croissante de services multimédia dans les réseaux Internet à haut débit, la technologie WIMAX a émergé comme une alternative compétitive à la solution filaire d’accès à haut débit. L’IEEE 802.16 constitue une solution qui offre des débits élevés en assurant une qualité de service (QoS) satisfaisante. En particulier, elle est adaptée aux applications multimédia qui ont des contraintes de QoS à satisfaire. Cependant, avec la présence d’utilisateurs hétérogènes qui ont des caractéristiques diverses en termes de bande passante, de conditions radio et de ressources disponibles, de nouveaux défis posés doivent être résolus. En effet, les applications multimédia doivent interagir avec leur environnement pour informer le réseau d’accès de leurs besoins en QoS et s’adapter dynamiquement aux variations des conditions du réseau.Dans ce contexte, nous proposons deux solutions pour la transmission des flux vidéo sur les réseaux 802.16 sur la base de l’approche Cross-layer. Nous nous intéressons à la fois à la transmission unicast et multicast sur le lien montant et descendant d’une ou plusieurs cellules WIMAX.Premièrement, nous proposons une architecture Cross-Layer qui permet l’adaptation et l’optimisation du streaming vidéo en fonction des ressources disponibles. Nous avons défini une entité CLO (Cross-Layer Optimizer) qui exploite des messages de gestion des flux de service, échangés entre BS et SS, au niveau MAC, pour déterminer l’adaptation nécessaire et optimale afin d’assurer le bon fonctionnement de l’application. Les adaptations se produisent en deux temps, lors de l'admission du flux et au cours de la session de streaming. L’analyse des performances, par simulations, de notre solution montre l’efficacité du CLO à adapter, d’une façon dynamique, le débit vidéo en fonction des conditions du réseau afin d’assurer une QoS optimale.Deuxièmement, nous proposons une solution de streaming multicast des flux vidéo dans les réseaux WIMAX. Cette solution permet de trouver un compromis entre la diversité des clients, en termes de conditions radio, de schémas de modulation et de ressources disponibles, ainsi que le format de codage vidéo hiérarchique SVC, pour offrir la meilleure qualité vidéo y compris pour les clients ayant de faibles conditions radio. En effet, cette solution permet à chaque utilisateur d’obtenir une qualité vidéo proportionnellement à ses conditions radio et à sa bande passante disponible. Pour atteindre cet objectif, plusieurs groupes multicast sont formés par couches vidéo SVC. Cette solution permet d’optimiser davantage les ressources radio et ainsi d’augmenter la capacité globale du système. / Driven by the increasing demand for multimedia services in broadband Internet networks, WIMAX technology has emerged as a competitive alternative to the wired broadband access solutions. The IEEE 802.16 is a solution that provides high throughput by ensuring a satisfactory QoS. In particular, it is suitable for multimedia applications that have strict QoS constraints. However, the users’ heterogeneity and diversity in terms of bandwidth, radio conditions and available resources, pose new deployment challenges. Indeed, multimedia applications need to interact with their environment to inform the access network about their QoS requirements and dynamically adapt to changing network conditions.In this context, we propose two solutions for video streaming over 802.16 networks based on Cross-Layer approach. We are interested in both unicast and multicast transmissions in uplink and downlink of one or more WIMAX cells.First, we proposed an architecture that enables Cross-Layer adaptation and optimization of video streaming based on available resources. We defined the entity CLO (Cross-Layer Optimizer) that takes benefits from service flow management messages, exchanged between BS and SS, at the MAC level, to determine the necessary adaptations / adjustment to ensure optimal delivery of the application. Adaptations occur at two epochs, during the admission of the video stream and during the streaming phase. The performance analysis, performed through simulations, shows the effectiveness of the CLO to adapt in a dynamic way, the video data rate depending on network conditions, and thus guarantee an optimal QoS.Second, we proposed a solution that enables IP multicast video delivery in WIMAX network. This solution allows finding the compromise between the diversity of end-user requirements, in terms of radio conditions, modulation schemes and available resources, along with the SVC hierarchy video format, to offer the best video quality even for users with low radio conditions. Indeed, we define a multicast architecture that allows each user to get a video quality proportionally to its radio conditions and its available bandwidth. Towards this end, several IP multicast groups are created depending on the SVC video layers. Subsequently, our solution allows optimizing the use of radio resources by exploiting the different modulations that can be selected by the end-users.

Actuellement, nous constatons une augmentation de demande de services vidéo sur les réseaux P2P. Ces réseaux jouent un rôle primordial dans la transmission de contenus multimédia à grande échelle pour des clients hétérogènes. Cependant, le déploiement de services vidéo temps réel sur les réseaux P2P a suscité un grand nombre de défis dû à l’hétérogénéité des terminaux et des réseaux d’accès, aux caractéristiques dynamiques des pairs, et aux autres problèmes hérités des protocoles TCP/IP, à savoir les pertes de paquets, les délais de transfert et la variation de la bande passante de bout-en-bout. Dans ce contexte, l’objectif de cette thèse est d’analyser les différents problèmes et de proposer un mécanisme de transport vidéo temps réel avec le provisionnement de la qualité de Service (QoS). Ainsi, nous proposons trois contributions majeures. Premièrement, il s’agit d’un mécanisme de streaming vidéo adaptatif permettant de sélectionner les meilleurs pair émetteurs. Ce mécanisme permet de structurer les pairs dans des réseaux overlay hybrides avec une prise en charge des caractéristiques sémantiques du contenu et des caractéristiques physiques du lien de transport. Nous présentons ensuite un mécanisme d’ordonnancement de paquets vidéo combiné à une commutation de pairs et/ou de flux pour assurer un transport lisse. Finalement, une architecture de collaboration entre les applications P2P et les fournisseurs de services / réseaux est proposée pour supporter un contrôle d’admission de flux. / There is an increasing demand for scalable deployment of real-time multimedia streaming applications over Internet. In this context, Peer-to-Peer (P2P) networks are playing an important role for supporting robust and large-scale transmission of multimedia content to heterogeneous clients. However, the deployment of real-time video streaming applications over P2P networks arises lot of challenges due to heterogeneity of terminals and access networks, dynamicity of peers, and other problems inherited from IP network. Real-time streaming applications are very sensitive to packet loss, jitter / transmission delay, and available end-to-end bandwidth. These elements have key importance in QoS provisioning and need extra consideration for smooth delivery of video streaming applications over P2P networks. Beside the abovementioned issues, P2P applications lack of awareness in constructing their overlay topologies and do not have any explicit interaction with service and network providers. This situation leads to inefficient utilization of network resources and may cause potential violation of peering agreements between providers. The aim of this thesis is to analyze these issues and to propose an adaptive real-time transport mechanism for QoS provisioning of Scalable Video Coding (SVC) applications over P2P networks. Our contributions in this dissertation are threefold. First, we propose a hybrid overlay organization mechanism allowing intelligent organization of sender peers based on network-awareness, media- awareness, and quality-awareness. This overlay organization is further used for an appropriate selection of best sender peers, and the efficient switching of peers to ensure a smooth video delivery when any of the sender peers is no more reliable. Second, we propose a packet video scheduling mechanism to assign different parts of the video content to specific peers. Third, we present a service provider driven P2P network framework that enables effective interaction between service / network providers and P2P applications to perform QoS provisioning mechanism for the video streaming.

Bakgrunden till detta projekt är att Vattenfall Eldistribution AB (nedan kallat Vattenfall) kommer att införa ett avgiftssystem för inmatning av reaktiv effekt till sitt elnät. Avgiften införs till följd av problem på elnätet som orsakas av reaktiv effekt. Umeå Energi Elnät AB (nedan kallat Umeå Energi) har historiskt matat in reaktiv effekt vilket motiverade detta arbete som utreder den reaktiva effekten på Umeå Energis elnät samt bidrar med information om två alternativa tillvägagångssätt att bemöta avgiften. Alternativ 0 är att kompensationsutrustning inte installeras, utan att ett abonnemang på inmatning av reaktiv effekt upprättas. Alternativ 1 är att kompensationsutrustning installeras. För att utreda den reaktiva effekten erhölls och behandlades data på reaktiv effekt i Umeå Energis nät. Historisk kondensatordrift togs fram för år 2016 ur händelsehistoriken hos Umeå Energis driftcentral. Kondensatordriften år 2015 kunde enbart erhållas från ett tidigare arbete på Umeå Energi eftersom ett begränsat antal händelser lagras i händelsehistoriken. Genom att subtrahera kondensatorernas produktion från den reaktiva effekten i Umeå Energis anslutningspunkter som uppmätts av Vattenfall erhölls data som mer representerade underliggande fenomen på nätet. Utan kondensatordrift beräknades inmatningen enligt Vattenfalls definition uppgå till cirka 34 MVAr utifrån data från 2015 och 2016. För åren 2018 till och med 2023 beräknades ändringar i reaktiv effekt till följd av förändringar på Umeå Energis nät. Vid beräkningarna försummades ledningarnas induktiva karaktär, vilket gav ett tomgångsscenario med maximal produktion av reaktiv effekt. År 2023 beräknades inmatningen ska ha ökat till 59 MVAr till följd av förändringar på Umeå Energis nät. Med antagandet att Umeå Energi inte kommer att drifta kondensatorbatterierna så att inmatningen höjs föreslogs för alternativ 0 val av abonnemang på inmatning av reaktiv effekt för åren 2018 till och med 2023 utifrån de 34 MVAr som nämnts ovan och inverkan från förändringarna på nätet. År 2019 föreslogs ett abonnemang på 41 MVAr, och 2023 föreslogs ett på 59 MVAr. Kostnaderna för dessa beräknades enligt Vattenfalls tariff till 820 000 kr respektive 1 187 000 kr. Kostnaden för eventuell överinmatning av reaktiv effekt beräknades med tariffen för överinmatning årligen uppgå till maximalt 76 000 kr med 95 % sannolikhet enligt den korrigerade standardavvikelsen hos inmatningen utan kondensatordrift åren 2015 och 2016. Optimal kondensatordrift beräknades för åren 2015 och 2016 genom att addera den produktion av reaktiv effekt från befintliga kondensatorbatterier som gav minst absolutvärde i reaktiv effekt. Beroende på hur ofta kondensatordriften justerades erhölls olika resultat. En undersökning av störningar till följd av kondensatorkopplingar rekommenderas för att få en förståelse för förutsättningarna för optimal kondensatordrift. Det bedömdes inte ekonomiskt motiverbart med mer avancerad kompensationsteknik såsom statiska VAr-kompensatorer då variabla reaktorer kan kompensera dygns- och säsongsvariationer i reaktiv effekt. Den reaktiva effektproduktionen i ledningar är störst på 145 kV-nivån och kommer öka i framtiden på denna nivå. Det är därför sannolikt här kompensationsutrustning såsom reaktorer först bör installeras. För att kunna ta så bra beslut som möjligt angående den reaktiva effekten rekommenderas att snarast möjligt ingå ett arbetssätt som om avgiftssystemet redan tagits i bruk och utöka ett representativt dataunderlag. / The background of this project is that Vattenfall Eldistribution AB (hereinafter referred to as Vattenfall) will establish a system of fees for input of reactive power. This will be done due to problems in the grid caused by reactive power. Umeå Energi Elnät AB (hereinafter referred to as Umeå Energi) has historically input reactive power, motivating this work which investigates the reactive power in the grid of Umeå Energi and provides information on two alternative approaches to responding to the fee. Alternative 0 entails no installation of compensation technology, and that a subscription for reactive power input is established instead. Alternative 1 entails that compensation technology is installed. To investigate the reactive power, data on reactive power in the grid of Umeå Energi were obtained and processed. Historical operations of capacitor banks for the year 2016 were obtained from the history of events of the control center at Umeå Energi. The operations of the capacitor banks during 2015 could only be obtained from an earlier work at Umeå Energi since the number of events stored in the history is limited. By subtracting the capacitor banks’ production from the reactive power measured by Vattenfall in the connections of Umeå Energi, data more representative of underlying phenomena were obtained. Without capacitor production of reactive power, the input was calculated according to the definition of Vattenfall to about 34 MVAr, by using data from 2015 and 2016. For the years 2018 through 2023, changes in reactive power due to changes in the grid of Umeå Energi were calculated. These calculations did not consider inductances, and thus yielded zero-load scenarios with maximum reactive power production. By the year of 2023, the input was calculated to have increased to 59 MVAr due to changes in the grid of Umeå Energi. Assuming that Umeå Energi will not operate the capacitors so that the input is increased, for alternative 0 subscriptions for input of reactive power were suggested for the years 2018 through 2023 by considering the abovementioned 34 MVAr and the changes in the grid. Subscriptions of 41 MVAr and 59 MVAr were suggested for the years 2019 and 2023 respectively. The costs of these were calculated with the fee specified by Vattenfall to SEK 820,000 and SEK 1,187,000 respectively. Calculations with the applicable fee yielded that the yearly cost of possible over-input could amount to a maximum of SEK 76,000 with a 95 % probability, using the corrected standard deviation of the input without capacitor production of reactive power for the years 2015 and 2016. Optimal capacitor bank operations were calculated for the years 2015 and 2016 by adding the production of reactive power from existing capacitor banks which yielded the minimum absolute reactive power. Depending on how often the capacitors were operated different results were obtained. An investigation of power quality disturbances due to capacitor bank operations is recommended to achieve an understanding of the conditions for optimal capacitor bank operations. It was not deemed economically justifiable to install more advanced compensation technologies such as static VAr compensators since variable reactors are able to compensate daily and seasonal variations in reactive power. The production of reactive power in cables is the largest on the 145 kV level and will increase in the future on this level. It is therefore likely here compensation technologies such as reactors should be installed first. To be able to make as good decisions as possible concerning the reactive power, it is recommended to as soon as possible commence a working method as if the fee system had already come into effect; thus increasing the amount of representative data.

Made available in DSpace on 2016-08-17T14:52:43Z (GMT). No. of bitstreams: 1 Gilson Soares da Silva Junior.pdf: 3373997 bytes, checksum: f03b490d45ba68e7ae2eacd3f33b718a (MD5) Previous issue date: 2008-02-15 / In this work is analyzed the influence of a static var compensator (SVC) on the electromechanical stability of the electrical energy system of the industrial consumer ALUMAR that has a cogeneration. The main considerations on cogeneration systems, the FACTS Controllers and the systems involved in the analysis are described. Moreover, it is discussed the modeling of electrical system of ALUMAR highlighting the modeling updated and validated by the National Electric System Operator (ONS) and the modeling of cogenerators. / Análise da influência de um compensador estático de reativos (SVC) na estabilidade eletromecânica do sistema de energia elétrica do consumidor industrial ALUMAR o qual possui cogeração. Descrevem-se as principais particularidades sobre os sistemas de cogeração, os controladores FACTS e sobre os sistemas envolvidos na análise. Discute-se, ainda, a modelagem do sistema elétrico da ALUMAR, destacandose a modelagem atualizada e validada pelo Operador Nacional do Sistema (ONS) e a modelagem dos cogeradores.

Småskalig vattenkraft är en stor användare av reaktiv effekt då de ofta har asynkrongeneratorer. Det gör att det finns ett reellt behov för faskompensering, dels för att minska distorsion i nätet samt för att förbättra deras ekonomiska ställning, då elbolag ofta tar ut en avgift för överskridande användning av reaktiv effekt. Det ligger också i allmänhetens intresse att ha en god elkvalitet och hålla störningar och avbrott nere, vilket kan erhållas med faskompensering och filtrering av övertoner. Det finns olika tekniker för faskompensering med sina respektive för- och nackdelar som specificeras efter anläggningens krav och förhållanden. Dessa tekniker är ett kondensatorbatteri, passiv och aktiv reglering, övermagnetiserad synkronmaskin, static var compensator (SVC) och static synchronous compensator (STATCOM). Med hjälp av simuleringar och ekonomisk kalkylering har deras egenskaper och investeringspotential analyserats. Det har resulterat i att ett kondensatorbatteri är en ekonomiskt god investering men med nackdelen att det blir en stor transient vid inkoppling. Aktiv reglering bistår med en snabb, kontinuerlig faskompensering men har större driftkostnader och en kortare livslängd. Övermagnetiserad synkronmaskin har en god ekonomisk framtidsutsikt men med en något långsammare reaktionstid. SVC och STATCOM är mer applicerbar på större anläggningar, eller för nät som har en större nytta av dess flexibilitet. / Small scale hydropower is a big user of reactive power, mainly because of their use of asynchrounous generators. Power companies are charging their customers a fee for an extensive use of reactive power. Which gives rise to a need of correction of the power factor as well as reduction of distorsion in the network. It is also in the interest of the general public to acquire a good electric quality in terms of keeping distorsion and interruptions in the network to a minimum. This can be achieved by using different methods for power factor correction and filtration of harmonics. These methods have their own inherent advantages and disadvantages described after the facility’s specific needs and requirements. These methods are a capacitor bank, passive and active regulation, overexcited synchronous machine, static var compensator (SVC) and static synchronous compensator (STATCOM). Simulations and economical calculations have been used to determine these properties. A capacitor bank has been proven to be a good economical investment, but it has high transients during switching conditions. Active regulation also shows a good profitability and provides a fast, continuous regulation of the reactive power, though it has higher operating costs and low life expectancy. The overexcited synchronous generator has a positive outlook in economic terms, with the drawback of a slower response time. SVC and STATCOM are more applicable to larger facilities or weak networks.