Este trabalho apresenta uma avaliação do algoritmo EBS, uma política de escalonamento proposta para sistemas de tempo real flexíveis com qualidade de serviço baseado em limites superiores para tempos médios de resposta. Experimentos têm demonstrado propriedades vantajosas da política EBS em servidores Web com diferenciação de serviço. O objetivo do presente estudo é compreender o comportamento da EBS em relação à diferentes parâmetros que descrevem a carga de trabalho. Esse conhecimento é útil para obtenção de um melhor aproveitamento computacional. São apresentados experimentos e resultados que analisam a influência de cada um dos fatores considerados na qualidade do serviço oferecido. A partir desses resultados são tecidas conclusões acerca de abordagens para o dimensionamento de carga e de capacidade do servidor / This Master degree project has presented an evaluation of the EBS algorithm, a scheduling policy proposed for soft real-time systems with quality of service based on upper limits for average response times. Experiments have shown advantageous properties of the EBS policy on Web servers with service differentiation. The aim of this study is to understand the behavior of the EBS in relation to different parameters that describe the workload. This knowledge is useful for obtaining a better use of computing. Experiments and results are presented analyzing the influence of each factor considering the quality of service offered. From these results, conclusions are woven about approaches to the design load and server capacity

Este trabalho de pesquisa apresenta a fundamentação teórica da simulação de sistemas, a motivação e os objetivos para o estudo e o desenvolvimento de técnicas para efetuar a simulação em tempo real. Este trabalho apresenta o desenvolvimento da Arquitetura de Software da ferramenta de Engenharia denominada FASTR (Ferramenta de engenharia para Aplicação de Simulação em Tempo Real), que possui o objetivo de alimentar o sistema de simulação com dados da planta industrial em tempo real. Este trabalho também apresenta a arquitetura de Hardware empregada para testar e validar a FASTR. Os testes, resultados e análises obtidos com a FASTR são apresentados neste trabalho para comprovar e convalidar a aplicabilidade da mesma como ferramenta de engenharia para análise de projetos e de análise de desempenhos de plantas industriais automatizadas. / This research work presents the theoretical basis of systems simulation, the motivation and the objectives of study and development of techniques to execute real time simulation. This research work presents the development of Software Arquitecture of the engineering tool named FASTR (engineering tool for application of real time simulation in automated industrial plants), that has the objective of feeding the simulation system with data of the industrial plant in real time. This work also presents the used Hardware Architecture to test and to validate the FASTR. The tests, results and analyses obtained with the FASTR are presented in this work to prove and to validate the applicability of the same one as an engineering tool for analysis of projects and analysis of performances of automated industrial plants.

Les automates cellulaires sont un modèle de calcul massivement parallèle introduit dans les années 50. De nombreuses variantes peuvent être considérées par exemple en faisant varier la dimension de l’espace de calcul, ou les possibilités de communication entre les différentes cellules. En effet, chaque cellule ne peut communiquer qu’avec un nombre fini d’autres cellules que l’on appelle son voisinage. Mes travaux s’intéressent principalement à l’impact du choix du voisinage sur les capacités algorithmiques de ce modèle. Cet impact étant bien compris en une dimension, mes travaux portent majoritairement sur les automates cellulaires bidimensionnels. J’ai tout d’abord essayé de généraliser des propriétés classiques de certaines classes de complexité au plus de voisinages possibles. On arrive notamment à un théorème d’accélération linéaire valable pour tous les voisinages. J’ai ensuite étudié les différences entre les classes de faibles complexités en fonction du voisinage choisi. Ces travaux ont permis d’exhiber des voisinages définissant des classes incomparables, ainsi que des ensembles de voisinages définissant exactement les mêmes classes de complexité. Enfin, je présente aussi des travaux sur les différences de puissance de calcul entre les automates de dimensions différentes. / Cellular automata were introduced in the 50s by J. von Neumann and S. Ulamas an efficient way of modeling massively parallel computation. Many variations of the model can be considered such as varying the dimension of the computation space or the communication capabilities of the computing cells. In a cellular automaton each cell can communicate only with a finite number of other cells called its neighbors. My work focuses on the impact of the choice of the neighbors on the algorithmic properties of the model. My first goal was to generalize some classical properties of computation models to the widest possible class of neighborhoods, in particular I prove a linear speedup theorem for any two dimensional neighborhood. I then study the difference between the complexity classes defined by different neighborhoods, show the existence of neighborhoods defining incomparable classes, and some sets of neighborhoods defining identical classes. Finally, I also discuss the impact of the dimension of the automata on their computational power.

Este trabalho apresenta um estudo, implementação e validação em ambiente simulado de uma política de escalonamento de tempo real para provisão de QoS absoluto em serviço Web. Sintetizando características de escalonamento de tempo real, com baixa latência e de modelo re-alimentado, a política proposta permite um ajuste ponderado pela quantificação da exigência à qual o sistema está submetido por meio de suas classes. A meta é oferecer ações imediatas às requisições mais urgentes, sem, entretanto, degradar a qualidade do sistema como um todo. Verificou-se que a estratégia de escalonamento baseada em exigência (EBS - Exigency-Based Scheduling) é benéfica para o controle da qualidade de serviço oferecida. Escalonar de forma a evitar demasiado peso imposto ao sistema permite que o servidor tenha mais condições de cumprir os requisitos contratuais. Também foi alvo do estudo a criação de uma métrica de avaliação da satisfação de atendimento por parte dos usuários dos serviços. Os resultados alcançados com o emprego da política EBS sinalizam uma melhoria em termos de qualidade de serviço e melhor satisfação dos clientes de forma balanceada / The present work presents a study, implementation and validation in a simulated environment of a real time scheduling policy to provide absolute QoS for web services. Synthesizing characteristic from real time scheduling, low latency and feedback scheduling, the proposed policy allows an adjustment weighed by the quantification of the exigency which the system is exposed through its classes. The goal is to offer immediate actions to most urgent requests, without decreasing the system quality as a whole. It was verified that the scheduling strategy based on exigency (EBS - Exigency-Based Scheduling) helps to control the quality of service offered. Scheduling in order to avoid imposing a heavy load to the system gives more condition to the server to fulfill the requirements agreed. Another goal of this work is the creation of a metrics to evaluate the client satisfaction. The results achieved with the EBS policy indicate a higher quality of service and better client satisfaction

Quando se dispõe de um sistema de controle distribuído em tempo real, o atendimento aos requisitos temporais constitui-se num fator crucial para a aplicação. Assim, para garantir que tais requisitos sejam atendidos, é fundamental que o tráfego de mensagens no barramento seja gerenciado e controlado apropriadamente, evitando-se atrasos na comunicação para não prejudicar a performance do sistema e do produto final. Este trabalho apresenta um mestre PROFIBUS desenvolvido em PC, cujas finalidades foram analisar por meio de dados experimentais, a influência do parâmetro TTR no tempo de atualização das variáveis de processo no sistema e o tempo de reintegração da estação-mestre no anel lógico após perda de mensagem de token. / Using a real-time distributed control system, it is crucial to fullfill the time requirements for an application. Therefore, to guarantee that these requirements are fulfilled, it is essential to manage and control the message traffic in the bus properly, avoiding delays in the communication that could compromise the final product and the system performance. This study presents a PROFIBUS master based on PC. The main purpose of the PROFIBUS master is to analyze, using empirical data, the influence of the TTR parameter in the updating time of the process variables and the time interval to reintegrate a master device to the logical ring after a token message is lost.

Electronic equalization has recently attracted considerable interest for impairment compensation for its significant cost saving and adaptive compensation capability. In this thesis, we propose novel maximum-likelihood sequence estimation (MLSE) structures for various advanced modulation formats. Electronic equalization of advanced modulation formats further extends the transmission reach and relaxes the speed limitation of electronic devices. We also propose novel application of MLSE for mitigation of timing misalignment between the pulse carver and data modulator in return-to-zero (RZ) systems. / In access networks, we focus on the achievement of centralized light source (CLS) wavelength-division-multiplexing passive optical networks (WDM-PON) with data rate of 10 Gbit/s for both downstream and upstream signals. The previous CLS WDM-PON schemes at 10 Gbit/s suffer from chromatic dispersion (CD) and/or asynchronous upstream modulation. We propose two solutions to mitigate these impairments. By eliminating the modulation synchronization module and all-optical CD compensation module, the proposed methods greatly reduce the cost and operation complexity of high-speed WDM-PON. / In the monitoring for impairment compensation, we propose a polarization-insensitive monitoring scheme for synchronized phase re-modulation by using a narrowband optical-passband filter (OBPF). With the optimal central wavelength of the OBPF, high monitoring sensitivity is achieved. / The increasing bandwidth demands have aroused a myriad of industry and academic activities to develop cost-effective optical communication systems with data rates of 10 Gbit/s and beyond. However, as the capacity grows, many signal degradation effects become prominent and seriously limit the data rate and the transmission distance. The mitigation of the impairments inevitably increases the operation complexity and implementation cost. The focus of this thesis is to develop new impairment mitigation approaches to improve the impairment compensation performance and/or to reduce the operation complexity and cost. As a result, cost-effective high-speed optical communication systems are enabled. / To freely enable the employment of advanced modulation formats for optical communications, we propose all-optical conversion from 40-Gbit/s RZ signal to 40-Gbit/s inverse-RZ/10-Gbit/s differential-phase-shift-keying orthogonal modulation signal to interface high-speed transmission systems using RZ format with networks using orthogonal modulation format. We also propose a novel all-optical coding and decoding scheme for 20-Gbit/s four-amplitude-shift-keying signal. / Zhao Jian. / "July 2007." / Adviser: Lian-kuan Chen. / Source: Dissertation Abstracts International, Volume: 69-01, Section: B, page: 0579. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 152-173). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

This thesis presents investigations into the effect of modern wind farms on grid side short circuits using extensive real time digital simulation. Particular reference is made to adaptive autoreclosing algorithms using artificial neural networks. A section of 132kV transmission grid in Scotland, including DFIG wind farms, is modelled on a real time digital simulator. An algorithm is then developed and tested using this model to show that this autoreclosing technique is feasible in systems with high penetration of wind generation. Although based on an existing technique, an important innovation is the use of two neural networks for the separate tasks of arc presence and extinction. The thesis also describes a low-cost, real time, relay development platform.

Spectral rendering, or the synthesis of images by taking into account the wavelengths of light, allows effects otherwise impossible with other methods. One of these effects is dispersion, the phenomenon that creates a rainbow when white light shines through a prism. Spectral rendering has previously remained in the realm of off-line rendering (with a few exceptions) due to the extensive computation required to keep track of individual light wavelengths. Caustics, the focusing and de-focusing of light through a refractive medium, can be interpreted as a special case of dispersion where all the wavelengths travel together. This thesis extends Adaptive Caustic Mapping, a previously proposed caustics mapping algorithm, to handle spectral dispersion. Because ACM can display caustics in real-time, it is quite amenable to be extended to handle the more general case of dispersion. A method is presented that runs in screen-space and is fast enough to display plausible dispersion phenomena in real-time at interactive frame rates.

We have built an application that integrates a technical editor feature and a custom real-time strategy game. The end users are able to use the technical editor feature for tweaking and customizing the unit attributes and progressions in the game using simple mathematical formulas, and they can play or test their tweaked formulas within the game. Various game modes in the software, which are Single Player, Multiplayer, and Simulation, can help display to the end users the results of their tweaked formulas, or users can just have fun by playing the game. The software was evaluated to see whether the software with the editor feature enabled is more attractive and appealing to the end users than the software with the editor feature disabled. The evaluation is based on the players’ feedback on the game with or without the editor. A total of 50 testers were randomly assigned into 2 groups evenly, the Tool group and the Game group. Testers assigned to the Tool group were able to customize the game unit attributes via the editor and play, while the testers in the Game group only play the game. The results from the post-test survey show both versions of the software are highly appealing to the testers, and there is no significant difference in game appeals between the Tool version and the Game version.

We are studying the use of tilt-enabled handheld touchscreen devices as an interface for top-down strategy games. We will explore how using different input modes (tilt and touch) compare for certain tasks in terms of efficiency and comfort. Real-time and turn-based strategy games are a popular form of electronic gaming, though these games currently have only minor representation on tablets. This genre of game requires both a wide variety of input and the display of a wealth of information. We are exploring whether, with suitable interface developments, this genre can become as accessible on tablet devices as on traditional computers. These interface approaches may also prove useful for expanding the presence of other game genres in the mobile space.