Em aplicações distribuídas baseadas em agentes móveis, a coordenação das ações dos agentes móveis é uma tarefa complexa. A maior dificuldade é devido ao fato que agentes móveis podem mudar de endereço dinamicamente. Nesta dissertação, apresentamos o projeto e a implementação de um mecanismo de coordenação de agentes móveis que contorna este problema. Este mecanismo, que chamamos de Canal de Broadcast, está baseado na difusão de mensagens e possibilita que os membros de um grupo de agentes móveis interajam entre si, independentemente de suas localizações correntes. Modelos de coordenação existentes oferecem formas de interação entre agentes móveis, mas todos eles impõem alguma exigência. Ou os agentes móveis devem conhecer a localização de outros agentes, ou devem estar localizados no mesmo lugar ou devem migrar para um lugar específico. A principal vantagem deste mecanismo de coordenação está na total transparência de localização: as mensagens podem ser endereçadas a um conjunto de agentes móveis independentemente de sua localização corrente. Este mecanismo foi implementado no ASDK (Aglets Software Development Kit) da IBM e a sua utilidade foi demonstrada usando dois problemas típicos de coordenação em Sistemas Distribuídos: a Exclusão Mútua e o protocolo Manager-Workers. Testamos o desempenho do mecanismo e identificamos que o custo do Canal de Broadcast não é tão alto comparado aos benefícios que proporciona. Através deste mecanismo, os agentes móveis poderão executar as suas tarefas e interagir entre sí com o propósito da coordenação sem as exigências impostas por outros modelos de coordenação. / In distributed applications based on mobile agents, the coordination of mobile agents actions is a difficult task. The main difficulty comes from the fact that mobile agents can change their address dynamically. In this dissertation, we present the project and implementation of a mechanism for coordinating mobile agents that overcomes this problem. This mechanism, which we called Broadcast Channel, is based on the difusion of messages and enables the members of a mobile agent group to interact with each other independently of their current locations. Existing coodination models offer some means of interaction between mobile agents, but all of them impose some requirements. Either the mobile agents must know about each other's location, or must be located at the same place or must move to a specific place. The main advantage of our coordination mechanism is the full location transparency: the messages can be sent to a set of mobile agents independently of their current locations. This mechanism was implemented using IBM's ASDK (Aglets Software Development Kit) and its use was demonstrated using two typical coordination problems in Distributed Systems: the Mutual Exclusion and the Manager-Workers protocol. We tested the performance of the mechanism and identified that the cost of the Broadcast Channel is not too high, compared to the benefit it provides. Through this mechanism, the mobile agents can do their tasks and interact with each other for the purpose of coordination without the requirements imposed by other models.

This study is an historical and critical analysis of pirate radio in Europe generally and Great Britain in particular. The purpose of this study is to outline the history of pirate radio, and to assess its influence upon the British radio broadcast system. Research material employed in this study includes historical accounts of pirate radio in Europe, British Governmental documents, periodical articles, and autobiographies of relevant British politicians of the period. This study concludes that the establishment of a legal commercial radio broadcast system in 1972 was a direct result of the existence of the British off-shore "pirate" radio stations from 1964 to 1967.

O sistema de emissoras afiliadas da Rede Globo de Televisão consolidou-se no Brasil na década de 1970, já no período técnico, científico e informacional, com a intensificação de densidades técnicas, informacionais e normativas no território nacional. A empresa, ao organizar este sistema, cria uma divisão territorial do trabalho que transforma as afiliadas em unidades de produção de informações para a sede, enquanto ela produz a maior parte da programação que é transmitida pelas afiliadas. A existência de uma tecnosfera (torres de recepção e retransmissão, links de microondas e captação do sinal do satélite, etc.) e de uma psicosfera (ideologia do progresso que se transmite com a programação da emissora nacional tradicionalmente reconhecida pela sua qualidade técnica) cria as condições para que este sistema funcione com uma alta capilaridade territorial e se imponha verticalmente nos lugares. A empresa Rede Globo de Televisão estabelece uma solidariedade organizacional no território brasileiro através da relação com suas emissoras afiliadas, utilizando-se de normas rígidas com padrão comercial, jornalístico e técnico. As emissoras locais, por acatarem estas ordens, deixam de criar suas próprias regras baseadas nas necessidades dos lugares onde estão instaladas. A programação nacional é produzida a partir das referências culturais, sociais e morais da Região Concentrada (onde se localizam as duas principais emissoras próprias da empresa) e é oferecida ao país como legítima expressão da cultura brasileira. A produção de programação local, verificada em quatro afiliadas do Estado de São Paulo (TV TEM Bauru, EPTV Campinas, TV Fronteira de Presidente Prudente e TV Tribuna de Santos), corresponde a menos de 5% da programação total da Rede Globo, o que revela o predomínio da programação nacional como um vetor nos lugares. / The system of broadcast affiliated of Rede Globo Television consolidated in the Brazil in the 1970s, in the scientific and technical information era, with the intensification of technical, informational and normative densities within the national territory. The company, in order to organize this system, established a territorial division of labor that transforms the affiliates in the production units of information to headquarters, while it produces the bulk of programming that is transmitted by affiliates. The existence of a technosfera (for the reception and relay towers, microwave links, and capture the signal from the satellite, etc.). And a psichosfera (ideology of progress that is transmitted with the national broadcaster signal, traditionally recognized for its technical quality) creates the conditions so that this system operates with a high territorial capillarity and vertically imposes its transmittion everywhere. The Rede Globo Television Company provides an organizational solidarity in Brazilian territory through the relationship with its affiliated stations, using rigid rules - with commercial, technical and journalistic standards. Local broadcasters by accepting these orders no longer dare to create their own rules based on the needs of the places where they are installed. The national programming is produced from the cultural, social and moral references of Concentrated Area (where are located the two main broadcasters owned by the company) and is offered to the country as a legitimate expression of Brazilian culture. The production of local programming, found in four affiliates of the State of Sao Paulo (TV TEM Bauru, EPTV Campinas, TV Fronteira de Presidente Prudente and TV Tribuna de Santos) represents less than 5% of the total programming of Rede Globo, revealing the predominance of national programming as a vector in all the places achieved by the company signal.

Uma tendência recente em sistemas de computação é distribuir a computação entre diversos processadores físicos. Isto conduz a dois tipos de sistemas: sistemas fortemente acoplados e sistemas fracamente acoplados. Este trabalho enfoca os sistemas de computação classificados como fracamente acoplados, ou sistemas distribuídos, como são popularmente conhecidos. Um sistema distribuído, segundo [BAB 86], pode ser definido como um conjunto de processadores autônomos que não compartilham memória, não tem acesso a clocks' globais e cuja comunicação é realizada somente por troca de mensagens. As exigências intrínsecas de sistemas distribuídos compreendem a confiabilidade e a disponibilidade. Estas exigências tem levado a um crescente interesse em técnicas de tolerância a falhas, cujo objetivo é manter a consistência do sistema distribuído, mesmo na ocorrência de falhas. Uma técnica de tolerância a falhas amplamente utilizada em sistemas distribuídos é a técnica de difusão confiável. A difusão confiável é uma técnica de redundância de software, onde um processador dissemina um valor para os demais processadores em um sistema distribuído, o qual esta sujeito a falhas [BAB 85]. Por ser uma técnica básica de comunicação, diversos procedimentos de tolerância a falhas baseiam-se em difusão confiável. Este trabalho descreve a implementação de um ambiente de apoio a sistemas distribuídos intitulado Ambiente para Experimentação e Avaliação de Protocolos de Difusão Confiável (ADC). Neste ambiente são utilizados os recursos da difusão confiável para a obtenção de uma concordância entre todos os membros do sistema livres de falha. Esta concordância, conhecida como consenso, é obtida através de algoritmos de consenso, os quais visam introduzir o grau de confiabilidade exigido pelos sistemas distribuídos. O ADC (Ambiente para Experimentação e Avaliação de Protocolos de Difusão Confiável) foi desenvolvido em estações de trabalho SUN (SunOS) utilizando o sistema operacional de rede heterogêneo HetNOS [BAA 93] desenvolvido na UFRGS. O ambiente foi implementado com base em um estudo realizado sobre protocolos de difusão confiável [BAR 94]. Através da implementação do ADC e possível simular a execução de protocolos de difusão confiável aplicando modelos propostos para os mesmos. Desta execução são extraídos resultados, sobre os quais pode-se realizar uma analise. Esta análise tem sua fundamentação principalmente nos parâmetros de desempenho, confiabilidade e complexidade. Tanto a implementação do ADC como a realização da analise do modelo proposto foram realizados tendo como suporte alguns dos protocolos de difusão confiável disponíveis na literatura. O principal objetivo deste ambiente consiste na experimentação, ou seja, na verificação da relação teórico-prática dos sistemas distribuídos perante a utilização de uma técnica de redundância de software, a difusão confiável. Através deste ambiente torna-se possível a determinação de parâmetros tais como o número de mensagens de difusão trocadas entre os processos, o número de mensagens de retransmissão enviadas, o número de mensagens emitidas durante todo o processamento do modelo, etc. Estes parâmetros resultam numa analise consistente de protocolos de difusão confiável. / A recent trend in computing systems is to distribute the computation between several physical processors. This leads to two different systems: closely coupled systems and loosely coupled systems. This work focuses on computing systems classified as loosely coupled or distributed systems, as they are commonly known. According to [BAB 86], a distributed system can be defined as a set of autonomous processors with no shared memory, no global clocks and whose comunication is performed only by message exchange. The inherent requirements of distributed systems include reliability and availability. These have caused an increasing interest in fault tolerance techniques, whose goal is to keep the distributed system consistent despite failures. A fault tolerance technique largely used in distributed systems is reliable broadcast. Reliable broadcast is a software redundancy technique, where a processor disseminates a value to other processors in a distributed system, in which failures can occur [BAB85]. Because it is a basic communication technique, several fault tolerance procedures are based on reliable broadcast. This work describes the implementation of a support environment for distributed systems called Reliable Broadcast Protocols Experimentation and Evaluation Environment (ADC). Reliable broadcast resources are used in this environment to obtain an agreement among all off-failure system components. This agreement, called consensus, has been obtained through consensus algorithms, which aim to introduce the reliability degree required in distributed systems. The ADC has been developed in Sun workstation (SunOS) using the heterogeneous operating system HetNOS [BAA 93] which was developed at UFRGS. The environment has been implemented based on a research about reliable broadcast protocols [BAR 94]. Through the ADC it is possible to simulate the execution of reliable broadcast protocols applying proposed models to them. From this execution results are extracted, and over them analysis can be done. This analysis has been based essentialy in parameters such as performance, reliability and complexity. Some classical reliable broadcast protocols were used as a support to ADC implementation and model analysis. The main goal of this environment consists in validating diffusion protocols in a practical distributed systems environment, facing reliable broadcast. Through this environment it can be possible the analysis of important parameters resolution such as the number of messages exchanged between process, the number of retransmission of messages sent, the number of messages sent during the whole model processing, others. These parameters result in a consistent analysis of reliable broadcast protocols.

Analysis of survey data collected from more than 400 LDS women (n=429) indicates that as the number of non-LDS or inactive LDS network associates increases, so does the women's identification with modern female TV characters. The frequency of network conversations about television also correlates to several television behaviors and attitudes such as watching entertainment and informational TV programming, identifying with modern characters, and regarding TV as useful. Mirroring the national trend, LDS women who are more educated use television less. A model is presented which details the flow and impact of personal network influence on the television habits and attitudes of a group of LDS women. These findings support the theory of audience individuality even within a highly conservative religious group of media users.

This thesis examines the television reporters' verbal depictions of two rescue events, the rescue of Jessica McClure in 1987 and the rescue of three whales at Pt. Barrow, Alaska in 1988, in order to discover what rhetorical techniques were used to appeal to the public interest. Analog criticism, metaphorical analysis and pentadic analysis were used to discover the dominant language reporters chose. Three main conclusions were drawn from this analysis: (1) use of the dramatistic pentad showed how reporters focused public attention away from the purpose,(2) verbal and visual depictions cannot be separated when studying television news stories and (3) two different styles of depiction were used to portray two very similar events.

The thesis examines the O.J. Simpson murder trial and analyzes the racial narratives that affected its outcome and the way it is perceived by the American public. By examining four books about the trial written by lawyers who served on the case, the analysis focuses on how race functions within each of the reconstructed narratives, as well as within the framework of the U.S. criminal justice system. The author argues that racial narratives affect how and why people can see the same event differently, a prime example of which is the O.J. Simpson murder trial. Representations of Mark Fuhrman, his role in the O.J. Simpson trial, and how these are affected by racial narratives are also discussed. The author concludes that the O.J. Simpson murder trial presented an opportunity in which issues concerning race, race relations, and ideologies about race could be openly discussed.

<p>Cell Broadcast is a relatively old technique within the GSM-network which makes it possible to broadcast text messages to one or more cells in the network. As efforts in Sweden have been made to develop both traffic safety and information technology, the automotive telematics market is predicted to grow rapidly in the near future. The characteristics of Cell Broadcast make it especially suitable for automotive telematics services. The main purpose of this thesis is to investigate possible automotive telematics services based on Cell Broadcast and how these services can affect traffic safety. </p><p>The most important characteristics for Cell Broadcast in the automotive telematics market are close connection to the GSM/UMTS network, location-based information and information of push character. These characteristics allows the mobile operator to offer a number of automotive telematics services based on Cell Broadcast, some of them as service provider and some of them in joint ventures with car and mobile terminal manufacturers.</p>

This study examined the differences in reporting in Radio-Television of Serbia's (RTS) main newscast, Dnevnik 2, between the period of Slobodan Milosevic’s rule (1989-2000) and the period after the establishment of democracy in Serbia (2001-2009). The data were gathered by the content analysis of 63 RTS newscasts in the period 1989-2009. The research included quantitative analysis as well as additional observations of RTS newscasts noted at the time of coding. The major findings suggest that in the democratic period (2001-2009) RTS newscasts become shorter, more consistent in duration, less dedicated to coverage of state and ruling party officials’ activities, and more inclined to reporting about social issues and other political events. The number of voices in RTS newscasts became significantly higher. The overall reporting became more balanced and more diverse. At the same time RTS kept the old priority in news reporting which put Official Stories in leading positions and remained occasionally inclined to increase the number of Official Stories in times of important political events. Based on these results this study derived the following hypotheses for state/public service television stations in countries in transition: 1) consistency of duration of newscasts increases as the regime in the country becomes less controlling 2) the dominance of Official Stories decreases as the regime in the country becomes less controlling 3) the number of sound bites in newscasts increases as the regime becomes less controlling (the number of voices in newscasts increases as the democracy progresses), and 4) the coverage of Official Stories increases in times of important domestic political events, possibly those that have endangered national security, even if the regime becomes less controlling.

Le système OFDM (Orthogonal Frequency Division Multiplexing) utilise plusieurs sous-porteuses pour transmettre de l'information. Comparé à un schéma mono-porteuse, la modulation multi-porteuses OFDM permet d'obtenir facilement des réglages optimaux (au sens de la capacité de Shannon) pour une transmission à haut débit sur un canal sélectif en fréquence. En ce sens, on peut alors garantir une transmission fiable et une meilleure gestion de l'énergie utilisée. Lors de la transmission avec une modulation OFDM, les sous-porteuses utilisent des canaux différents qui n'ont pas forcement la même atténuation. Allouer le même niveau de puissance à chaque sous-porteuse ne garantit pas une capacité optimale dans une liaison point à point. Une allocation dynamique de la puissance (c'est-à-dire attribuer différents niveaux de puissance aux sous-porteuses en fonction du canal) donne de meilleures performances. Par contre, dans une situation de diffusion (broadcast), l'émetteur ne connaît pas les canaux vers tous les utilisateurs, et la meilleure stratégie consiste à émettre avec la même puissance sur toutes les sous-porteuses. Cette thèse a pour objectif d'explorer les situations intermédiaires, et de proposer les outils d'allocation de puissance appropriés. Cette situation intermédiaire est appelée " multicast ", ou " multidiffusion " : l'émetteur envoie les signaux vers un nombre fini (pas trop grand) d'utilisateurs, dont il connaît les paramètres de canaux, et il peut adapter son émission à cette connaissance des canaux. On est donc dans une situation intermédiaire entre le " point à point " et la " diffusion ". L'objectif final de ce travail est d'évaluer le gain apporté par la connaissance des canaux en situation de multicast par rapport à la même communication effectuée comme si on était en diffusion. Bien évidemment, quand le nombre de destinataires est très grand, les gains seront négligeables, car le signal rencontre un nombre très élevé de canaux, et une allocation de puissance uniforme sera quasi optimale. Quand le nombre est très faible, on sera proche du point à point et les gains devraient être sensibles. Nous proposons des outils pour quantifier ces améliorations dans les cas de systèmes ayant une antenne à l'émission et une antenne à la réception, dit SISO (Single Input Single Output) et de systèmes avec plusieurs antennes, dits MIMO (Multiple Input Multiple Output). Les étapes nécessaires pour réaliser ce travail sont : 1) En supposant une connaissance préalable de l'état des canaux (entre station de base et terminaux), mettre en œuvre les outils de la théorie de l'information pour effectuer l'allocation de puissance et évaluer les capacités des systèmes étudiés. 2) Pour le système multi-utilisateur SISO-OFDM, nous proposons un algorithme d'allocation de puissance sur chaque sous porteuse dans une situation de multicast. 3) Pour le système multi-utilisateur MIMO-OFDM, nous proposons un algorithme qui exploite les caractéristiques du précodage "zero forcing". L'objectif est alors de partager la puissance disponible entre toutes les sous-porteuses et toutes les antennes. 4) Enfin, dans une dernière étape nous nous intéressons à une conception efficace de la situation de diffusion, afin de déterminer à l'aide d'outils de géométrie stochastique quelle zone peut être couverte afin qu'un pourcentage donné d'utilisateurs reçoivent une quantité d'information déterminée à l'avance. Ceci permet de déterminer la zone de couverture sans mettre en œuvre des simulations intensives. La combinaison de ces outils permet un choix efficace des situations qui relèvent de la " diffusion ", du " multicast " et du " point à point ".