CNPq, CAPES / O presente trabalho inclui a revisão das normas de qualidade de energia elétrica, a fim de normatizar o desenvolvimento do projeto seguindo normas nacionais e internacionais; a simulação de algoritmos como CFA e FFT, a fim de verificar a viabilidade de seu uso, bem como as limitações associadas ao processamento de formas de onda fortemente distorcidas. Inclui também a proposição e a verificação de um algoritmo capaz de calcular os índices (selecionados durante a revisão das normas) que pudessem avaliar a qualidade de energia através de sinais de tensão e corrente. Para o desenvolvimento do protótipo, foram selecionados sensores de tensão e de corrente confiáveis para o sistema de aquisição; um DSP, que executa os algoritmos previamente simulados, processando em tempo real os sinais adquiridos pelos sensores, a fim de reportar o estado da rede elétrica e/ou eventos ocorridos na rede através de um módulo ZigBee, responsável pela transmissão desses dados de forma segura. A classe de eventos de variação de tensão de curta duração foi incluída no processamento em tempo real realizado pelo DSP. Devido à imprevisibilidade e à rapidez da ocorrência desses eventos, foi desenvolvida uma ferramenta capaz de gerar essa classe de eventos, o gerador de VTCD. A análise de QEE em tempo real se mostrou viável mesmo com a utilização de dispositivos de baixo custo, permitindo, ainda que com algumas limitações, o levantamento de informações de QEE às quais cargas conhecidas estavam submetidas. / The present document includes a comprehensive literature review on power quality issues, to keep the development of this project aligned with national and international standards related; simulation algorithms such as FFT and CFA in order to verify the feasibility of its use, as well as limitations associated with the processing of strongly distorted waveform. It also includes the proposal and verification of an algorithm able to calculate the indices (selected during the standards review) that could assess the power quality through voltage and current signals. For prototype development, voltage and current sensors were selected for reliable acquisition system; a DSP, which running the previously simulated algorithms in order to process in real time the acquired voltage and current signals provided by sensors in order to report the status of the mains grid and/or events occurrence on the network through a ZigBee module, responsible for safety transmission data. The short term voltage change events class was also included in the real time processing performed by the DSP. Due to the unpredictability and short duration of these events, it was developed a tool capable of generating this class of events, the STVC generator. The PQ analysis in real time was feasible even with the use of low cost devices, allowing, although with some limitations, the survey of PQ information which known loads was submitted.

CNPq, CAPES / O presente trabalho inclui a revisão das normas de qualidade de energia elétrica, a fim de normatizar o desenvolvimento do projeto seguindo normas nacionais e internacionais; a simulação de algoritmos como CFA e FFT, a fim de verificar a viabilidade de seu uso, bem como as limitações associadas ao processamento de formas de onda fortemente distorcidas. Inclui também a proposição e a verificação de um algoritmo capaz de calcular os índices (selecionados durante a revisão das normas) que pudessem avaliar a qualidade de energia através de sinais de tensão e corrente. Para o desenvolvimento do protótipo, foram selecionados sensores de tensão e de corrente confiáveis para o sistema de aquisição; um DSP, que executa os algoritmos previamente simulados, processando em tempo real os sinais adquiridos pelos sensores, a fim de reportar o estado da rede elétrica e/ou eventos ocorridos na rede através de um módulo ZigBee, responsável pela transmissão desses dados de forma segura. A classe de eventos de variação de tensão de curta duração foi incluída no processamento em tempo real realizado pelo DSP. Devido à imprevisibilidade e à rapidez da ocorrência desses eventos, foi desenvolvida uma ferramenta capaz de gerar essa classe de eventos, o gerador de VTCD. A análise de QEE em tempo real se mostrou viável mesmo com a utilização de dispositivos de baixo custo, permitindo, ainda que com algumas limitações, o levantamento de informações de QEE às quais cargas conhecidas estavam submetidas. / The present document includes a comprehensive literature review on power quality issues, to keep the development of this project aligned with national and international standards related; simulation algorithms such as FFT and CFA in order to verify the feasibility of its use, as well as limitations associated with the processing of strongly distorted waveform. It also includes the proposal and verification of an algorithm able to calculate the indices (selected during the standards review) that could assess the power quality through voltage and current signals. For prototype development, voltage and current sensors were selected for reliable acquisition system; a DSP, which running the previously simulated algorithms in order to process in real time the acquired voltage and current signals provided by sensors in order to report the status of the mains grid and/or events occurrence on the network through a ZigBee module, responsible for safety transmission data. The short term voltage change events class was also included in the real time processing performed by the DSP. Due to the unpredictability and short duration of these events, it was developed a tool capable of generating this class of events, the STVC generator. The PQ analysis in real time was feasible even with the use of low cost devices, allowing, although with some limitations, the survey of PQ information which known loads was submitted.

A reactive control system is a computer system reacting to certain stimuli emitted by its environment in order to maintain it in a desired state. Distributed reactive control systems are generally composed of several processes, running in parallel on one or more computers, communicating with one another to perform the required control task. By their very nature, distributed reactive control systems are hard to design. Their distributed nature and/or the communication scheme used can introduce subtle unforeseen behaviours. When dealing with critical applications, such as plane control systems, or traffic light control systems, those unintended behaviours can have disastrous consequences. It is therefore essential, for the designer, to ensure that this does not happen. For that purpose, rigorous and systematic techniques can (and should) be applied as early as possible in the development process. In that spirit, this work aims at providing the designer with the necessary tools in order to facilitate the development and validation of such distributed reactive control systems. In particular, we show how using a dedicated language called dSL (Distributed Supervision language) can be used to ease the development process. We also study how validations techniques such as model-checking and testing can be applied in this context. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Indiana University-Purdue University Indianapolis (IUPUI) / A large portion of system breaches are caused by authentication failure either during the system login process or even in the post-authentication session, which is further related to the limitations associated with existing authentication approaches. Current authentication methods, whether proxy based or biometrics based, are hardly user-centric; and they either put burdens on users or endanger users' (biometric) security and privacy. In this research, we propose a biometrics based user-centric authentication approach. The main idea is to introduce a reference subject (RS) (for each system), securely fuse the user's biometrics with the RS, generate a BioCapsule (BC) (from the fused biometrics), and employ BCs for authentication. Such an approach is user-friendly, identity-bearing yet privacy-preserving, resilient, and revocable once a BC is compromised. It also supports "one-click sign on" across multiple systems by fusing the user's biometrics with a distinct RS on each system. Moreover, active and non-intrusive authentication can be automatically performed during the user's post-authentication on-line session. In this research, we also formally prove that the proposed secure fusion based BC approach is secure against various attacks and compare the new approach with existing biometrics based approaches. Extensive experiments show that the performance (i.e., authentication accuracy) of the new BC approach is comparable to existing typical biometric authentication approaches, and the new BC approach also possesses other desirable features such as diversity and revocability.

Indiana University-Purdue University Indianapolis (IUPUI) / The study of this thesis is focused on reducing the link failure detection time in OSPF network. When a link failure occurs, OSPF protocol detects it using RouterDeadInterval time. This timer is fired only after a predefined time interval, thus increasing the time of convergence after the link failure. There are previous studies to reduce the RouterDeadInterval time, but they introduce other effects which are discussed later in the thesis. So, a novel approach is proposed in this thesis to reduce the link failure detection time with the help of emerging network architecture Software Defined Networking (SDN) and OpenFlow Protocol.

A crescente demanda por ambientes de virtualização de larga escala, como os usados em datacenters e nuvens computacionais, faz com que seja necessário um gerenciamento eficiente dos recursos computacionais utilizados. Um dos recursos mais exigidos nesses ambientes é a memória RAM, que costuma ser o principal fator limitante em relação ao número de máquinas virtuais que podem executar sobre o mesmo host físico. Recentemente, hipervisores trouxeram mecanismos de compartilhamento transparente de memória RAM entre máquinas virtuais, visando diminuir a demanda total de memória no sistema. Esses mecanismos “fundem” páginas idênticas encontradas nas várias máquinas virtuais em um mesmo quadro de memória física, usando uma abordagem copy-on-write, de forma transparente para os sistemas convidados. O objetivo deste estudo é apresentar uma visão geral desses mecanismos e também avaliar seu desempenho e efetividade. São apresentados resultados de experimentos realizados com dois hipervisores populares (VMware e KVM), usando sistemas operacionais convidados distintos (Linux e Windows) e cargas de trabalho diversas (sintéticas e reais). Os resultados obtidos evidenciam diferenças significativas de desempenho entre os hipervisores em função dos sistemas convidados, das cargas de trabalho e do tempo. / The growing demand for large-scale virtualization environments, such as the ones used in cloud computing, has led to a need for efficient management of computing resources. RAM memory is the one of the most required resources in these environments, and is usually the main factor limiting the number of virtual machines that can run on the physical host. Recently, hypervisors have brought mechanisms for transparent memory sharing between virtual machines in order to reduce the total demand for system memory. These mechanisms “merge” similar pages detected in multiple virtual machines into the same physical memory, using a copy-on-write mechanism in a manner that is transparent to the guest systems. The objective of this study is to present an overview of these mechanisms and also evaluate their performance and effectiveness. The results of two popular hypervisors (VMware and KVM) using different guest operating systems (Linux and Windows) and different workloads (synthetic and real) are presented herein. The results show significant performance differences between hypervisors according to the guest system workloads and execution time.

Uma arquitetura distribuída é composta de diversos sistemas que trocam mensagens entre si. Falhas na integração destes sistemas podem ocorrer, exigindo uma investigação detalhada dos profissionais de suporte para encontrar a causa raiz do problema. O processo manual de identificação de falhas é difícil e demorado. Ganhos significativos podem ser obtidos através da automação do processo de classificação de falhas. Este trabalho tem por objetivo apresentar um método para auxílio no processo de diagnóstico de falhas, classificando automaticamente as falhas geradas em uma arquitetura orientada a serviços. Este método, denominado SOAFaultControl, se beneficia de arquiteturas distribuídas que adotam SOA e um Enterprise Service Bus (ESB). Utilizando-se de técnicas de aprendizado de máquina, foi possível estabelecer um modelo para classificação de falhas em categorias preestabelecidas. Para alcançar o objetivo deste trabalho foi necessário testar e avaliar os seguintes algoritmos de aprendizagem de máquina: Support Vector Machine, Naive Bayes e AdaBoost. Como resultado, o algoritmo Support Vector Machine obteve melhor desempenho nas métricas: acurácia, precisão, revocação e F1. / A distributed architecture is composed of many systems that exchange messages between each other. Faults in the integration of these systems may occur and they required a detailed investigation of support professionals to identifying the root cause of the problem. The manual process to identify causes of failure is difficult and time-consuming. Significant efficiency gains can be achieved by automating the faults classification process. This work presents a method to support the automated fault diagnostic process, automatically classifying faults generated in a Service Oriented Architecture (SOA). This method denominated SOAFaultControl, may be executed in a distributed architecture that adote SOA and an Enterprise Service Bus (ESB). Using machine learning techniques, was possible build a model to classify fault messages captured in a SOA environment, in pre-established classes. To achieve the objectives of this work it was necessary to test the following machine learning algorithms: Support Vector Machine, Naive Bayes, and AdaBoost. Results show that Support Vector Machine algorithm achieved better performance in the following metrics: precision, accuracy, recall, and F1.

Uma arquitetura distribuída é composta de diversos sistemas que trocam mensagens entre si. Falhas na integração destes sistemas podem ocorrer, exigindo uma investigação detalhada dos profissionais de suporte para encontrar a causa raiz do problema. O processo manual de identificação de falhas é difícil e demorado. Ganhos significativos podem ser obtidos através da automação do processo de classificação de falhas. Este trabalho tem por objetivo apresentar um método para auxílio no processo de diagnóstico de falhas, classificando automaticamente as falhas geradas em uma arquitetura orientada a serviços. Este método, denominado SOAFaultControl, se beneficia de arquiteturas distribuídas que adotam SOA e um Enterprise Service Bus (ESB). Utilizando-se de técnicas de aprendizado de máquina, foi possível estabelecer um modelo para classificação de falhas em categorias preestabelecidas. Para alcançar o objetivo deste trabalho foi necessário testar e avaliar os seguintes algoritmos de aprendizagem de máquina: Support Vector Machine, Naive Bayes e AdaBoost. Como resultado, o algoritmo Support Vector Machine obteve melhor desempenho nas métricas: acurácia, precisão, revocação e F1. / A distributed architecture is composed of many systems that exchange messages between each other. Faults in the integration of these systems may occur and they required a detailed investigation of support professionals to identifying the root cause of the problem. The manual process to identify causes of failure is difficult and time-consuming. Significant efficiency gains can be achieved by automating the faults classification process. This work presents a method to support the automated fault diagnostic process, automatically classifying faults generated in a Service Oriented Architecture (SOA). This method denominated SOAFaultControl, may be executed in a distributed architecture that adote SOA and an Enterprise Service Bus (ESB). Using machine learning techniques, was possible build a model to classify fault messages captured in a SOA environment, in pre-established classes. To achieve the objectives of this work it was necessary to test the following machine learning algorithms: Support Vector Machine, Naive Bayes, and AdaBoost. Results show that Support Vector Machine algorithm achieved better performance in the following metrics: precision, accuracy, recall, and F1.

Indiana University-Purdue University Indianapolis (IUPUI) / Asynchronous JavaScript and XML (AJAX) is the primary method for enabling asynchronous communication over the Web. Although AJAX is providing warranted real-time capabilities to the Web, it requires unconventional programming methods at the expense of extensive resource usage. WebSockets, which is an emerging protocol, has the potential to address many challenges with implementing asynchronous communication over the Web. There, however, has been no in-depth study that quantitatively compares AJAX and WebSockets. This thesis therefore provides two contributions to Web development. First, it provides an experience report for adding real-time monitoring support over the Web to the Open-source Architecture of Software Instrumentation of Systems(OASIS), which is open-source real-time instrumentation middleware for distributed real-time and embedded (DRE) systems. Secondly, it quantitatively compares using AJAX and WebSockets to stream collected instrumentation data over the Web in real-time. Results from quantitative comparison between WebSockets and AJAX show that a WebSockets server consumes 50% less network bandwidth than an AJAX server; a WebSockets client consumes memory at constant rate, not at an increasing rate; and WebSockets can send up to 215.44% more data samples when consuming the same amount network bandwidth as AJAX.

Indiana University-Purdue University Indianapolis (IUPUI) / Yan, Jiaxiang. M.S.E.C.E., Purdue University, May 2013. Modeling, Monitoring and Optimization of Discrete Event Systems Using Petri Nets. Major Professor: Lingxi Li. In last decades, the research of discrete event systems (DESs) has attracts more and more attention because of the fast development of intelligent control strategies. Such control measures combine the conventional control strategies with discrete decision-making processes which simulate human decision-making processes. Due to the scale and complexity of common DESs, the dedicated models, monitoring methods and optimal control strategies for them are necessary. Among various DES models, Petri nets are famous for the advantage in dealing with asynchronous processes. They have been widely applied in intelligent transportation systems (ITS) and communication technology in recent years. With encoding of the Petri net state, we can also enable fault detection and identification capability in DESs and mitigate potential human errors. This thesis studies various problems in the context of DESs that can be modeled by Petri nets. In particular, we focus on systematic modeling, asynchronous monitoring and optimal control strategies design of Petri nets. This thesis starts by looking at the systematic modeling of ITS. A microscopic model of signalized intersection and its two-layer timed Petri net representation is proposed in this thesis, where the first layer is the representation of the intersection and the second layer is the representation of the traffic light system. Deterministic and stochastic transitions are both involved in such Petri net representation. The detailed operation process of such Petri net representation is stated. The improvement of such Petri net representation is also provided with comparison to previous models. Then we study the asynchronous monitoring of sensor networks. An event sequence reconstruction algorithm for a given sensor network based on asynchronous observations of its state changes is proposed in this thesis. We assume that the sensor network is modeled as a Petri net and the asynchronous observations are in the form of state (token) changes at different places in the Petri net. More specifically, the observed sequences of state changes are provided by local sensors and are asynchronous, i.e., they only contain partial information about the ordering of the state changes that occur. We propose an approach that is able to partition the given net into several subnets and reconstruct the event sequence for each subnet. Then we develop an algorithm that is able to reconstruct the event sequences for the entire net that are consistent with: 1) the asynchronous observations of state changes; 2) the event sequences of each subnet; and 3) the structure of the given Petri net. We discuss the algorithmic complexity. The final problem studied in this thesis is the optimal design method of Petri net controllers with fault-tolerant ability. In particular, we consider multiple faults detection and identification in Petri nets that have state machine structures (i.e., every transition in the net has only one input place and one output place). We develop the approximation algorithms to design the fault-tolerant Petri net controller which achieves the minimal number of connections with the original controller. A design example for an automated guided vehicle (AGV) system is also provided to illustrate our approaches.