The present work studies the disturbances created in the electric system of a pumped storage power plant, which is an hydraulic generation facility where the machines can work as turbines or pumps, by the operation of a static frequency converter (SFC). The SFC is used for starting the synchronous machines at the station when in the pump mode. During the starting process several equipment is connected to the SFC being possible to get affected by the disturbances generated. These disturbances mainly include the creation of transient overvoltages during the commutation of the semiconductor devices of the SFC and the introduction of harmonics in the network currents and voltages. This work analyzes the possible effects of the SFC operation over the station equipment based on computer simulations. For this purpose, the complete system was modeled and the starting process simulated in a computer transient simulator program. The work begins with a general review of the effects of electric disturbances over high voltage equipment and in particular of the disturbances generated by power electronics conversion equipment. Then the models for the different kind of equipment present in the system are discussed and formulated. The control system that governs the operation of the SFC during the starting process is analyzed later as well as the operation conditions. Once the model of the system is set up, the harmonic analysis of the electric network is done by frequency domain and time domain methods. Time domain methods are also employed for the analysis of the commutation transient produced by the SFC operation. Finally, the simulation results are used to evaluate the impact of the SFC operation on the station equipment, especially on the generator step up transformer. / Master of Science

Master of Science / Department of Mechanical and Nuclear Engineering / Kirby S. Chapman / The purpose of this thesis is to present on the development and results of the cooling system logic tree and model developed as part of the Pipeline Research Council International, Inc (PRCI) funded project at the Kansas State National Gas Machinery Laboratory. PRCI noticed that many of the legacy engines utilized in the natural gas transmission industry were plagued by cooling system problems. As such, a need existed to better understand the heat transfer mechanisms from the combusting gases to the cooling water, and then from the cooling water to the environment. To meet this need, a logic tree was developed to provide guidance on how to balance and identify problems within the cooling system and schedule appropriate maintenance. Utilizing information taken from OEM operating guides, a cooling system model was developed to supplement the logic tree in providing further guidance and understanding of cooling system operation. The cooling system model calculates the heat loads experienced within the engine cooling system, the pressures within the system, and the temperatures exiting the cooling equipment. The cooling system engineering model was developed based upon the fluid dynamics, thermodynamics, and heat transfer experienced by the coolant within the system. The inputs of the model are familiar to the operating companies and include the characteristics of the engine and coolant piping system, coolant chemistry, and engine oil system characteristics. Included in the model are the various components that collectively comprise the engine cooling system, including the water cooling pump, aftercooler, surge tank, fin-fan units, and oil cooler. The results of the Excel-based model were then compared to available field data to determine the validity of the model. The cooling system model was then used to conduct a parametric investigation of various operating conditions including part vs. full load and engine speed, turbocharger performance, and changes in ambient conditions. The results of this parametric investigation are summarized as charts and tables that are presented as part of this thesis.

A modelagem de motores a combustão interna deve grande parte de sua importância ao uso de unidades de controle eletrônicas que buscam gerenciar as funções do motor. De forma a fornecer melhor suporte para o projetista de controle, a modelagem oferece informações que servem de planta, sobre a qual estratégias de controle serão desenvolvidas. Nesta dissertação, procurou-se estudar e modelar cinco fenômenos: a admissão de ar e de combustível, a produção de energia efetiva através da combustão, a evolução térmica do motor e o comportamento dos gases no sistema de exaustão. Investigou-se também, em todos estes fenômenos, a influência do uso de composição variada gasolina/etanol. Na admissão de ar, buscou-se estudar como a abertura da válvula borboleta e a velocidade do motor influenciam no fluxo de ar admitido, ponderando esta grandeza através de um fator de correção denominado eficiência volumétrica. Na admissão de combustível, no caso modelada para motores com injeção indireta na porta, procurou-se explanar quantitativamente sobre os diversos aspectos que influenciam a evaporação do combustível. Na geração de energia útil, priorizou-se a análise de como as características do motor e da combustão afetam a produção de torque. Na evolução térmica do motor, examinaram-se os principais fluxos energéticos do motor e os aspectos que os influenciam. Ademais, foram executadas as validações dos modelos levantados para o motor EA 111 VHT 1.6l. Os resultados, com seus respectivos erros, podem ser encontrados neste trabalho. / The internal combustion engine modeling owes big part of its importance to the use of electronic control units that aim to manage the engine functions. To provide better support to the control designer, the modeling offers information that can compose the plant, on which control strategies will be developed. In this master thesis, it was sought to study and to model five phenomena: the air intake and the fuel admission, the effective energy production from the combustion, the engine thermic evolution and the gas behavior in the exhaust system. It was also considered how the influence of the gasoline/ethanol varied composition affects all these phenomena. In the air intake, it was studied how the butterfly valve opening and the engine speed influence the intake air flow, pondering this variable through a correction factor named volumetric efficiency. In the fuel admission, in the case of this study modelled for port-fuel injection engines, it was attempted to explain quantitatively the many aspects that influence the fuel evaporation. In the mechanical energy generation, it was prioritized the analysis about how the engine and combustion characteristics affect the torque production. In the engine thermic evolution, it was examined the major energy flows and the aspects that influence them. Also, the validations of the models raised for the EA 111 VHT 1.6l engine were executed. The results, with its respective errors, can be found in this work.

Sistemas de suporte a decisão são utilizados em cenários com incertezas. Uma decisão normalmente é auxiliada por resultados obtidos com ações passadas em problemas semelhantes. Quando um sistema de suporte a decisão incorpora conhecimento específico de uma área, estes recebem o nome de sistemas especialistas. Tal conhecimento especifico é utilizado para inferência juntamente com as informações de entrada a respeito do problema. O objetivo deste trabalho é a avaliação e modelagem de sistemas de auxílio a decisão, foram analisadas duas abordagens para um mesmo problema alvo, sendo uma de gerenciamento do problema e outra de detecção do problema. A abordagem de gerenciamento utiliza redes Bayesianas para modelagem, tanto do conhecimento específico quanto para a inferência. As variáveis utilizadas, as relações de dependência e as probabilidades condicionais entre as variáveis foram extraídas da literatura. A abordagem de detecção do problema utilizou imagens para extração de características seguida de um algoritmo de agrupamento para comparação com a classificação de um especialista. Uma das áreas de aplicação de sistemas especialistas é na área clínica, podendo auxiliar tanto na detecção, diagnóstico e tratamento de doenças. A cárie dental é um problema generalizado que afeta a maioria das pessoas, tanto em países ricos, como em países pobres. Existem poucos sistemas para auxílio no processo de diagnóstico da cárie, sendo a maior parte dos sistemas existentes determinísticos, focando apenas na detecção da lesão. O sistema de gerenciamento da cárie desenvolvido foi apresentado a dois profissionais da odontologia, a opinião deles mostra que está abordagem é promissora e aplicável em campos como a educação e a atenção básica a saúde. Além da apresentação aos profissionais, foram utilizados casos bem estabelecidos da literatura para analisar as sugestões fornecidas pela Rede, e o resultado foi coerente com o cenário real de tomada de decisão. A metodologia de detecção da cárie resultou em um alto valor de acurácia, 96.88%, mostrando que tal metodologia é promissora em comparação com outros trabalhos da área. Além da contribuição para a área de informática odontológica, os resultados mostram que a extração da estrutura e das probabilidades condicionais da rede a partir da literatura é uma metodologia que pode ser utilizada em outras áreas com cenário similar ao do diagnóstico da cárie. Nos próximos passos do projeto alguns pontos referentes a modelagem de sistemas e redes Bayesianas serão analisados, como escalabilidade e testes de validação, tanto quantitativamente como qualitativamente, isto inclui o desenvolvimento de métodos computacionalmente efetivos para a geração de casos aleatórios utilizando o Método de Monte Carlo / Decision support systems are used in uncertainty scenarios; normally a decision is choose using similar problems actions results. Decision support systems could incorporate specific knowledge; such systems are called expert systems. The specific knowledge is used for inference about the problem scenario. This work objective is the evaluation and modeling of decision support systems, we analyzed two distinct approaches for the same problem, one for detection, another for management. The management approach uses Bayesian networks for modeling the specific knowledge and the inference engine. The variables choice, the dependences relationship and the conditional probabilities were extracted from the scientific literature. The detection approach used images and feature extraction to perform a clustering and compare the output labels with a specialist classification. One application of expert systems is clinical, supporting diseases detection, diagnosis and treatment. Dental caries is a generalized problem that affects major part of the population, few systems exists for support the caries diagnostic process, the major part is deterministic, focusing only the detection problem. The caries management system developed here was shown to two odontology professionals, and they opinion encourage such approach to be applied in fields like odontology education and basic health. Beyond this, we used well-established cases to analyze the network output suggestions, the result obtained was coherent with the real decision making scenario. The caries detection approach resulted in a high accuracy, 96.88%, showing that methodology is promising. Besides the contribution for dental informatics field, the results obtained here shows that the extraction of the network structure from the literature could be used in problems similar with caries diagnoses. The project next steps are to analyze some points of systems modeling and Bayesian networks, like scalability and validation tests, both quantitative and qualitative, and including the development of computational effectives methods for the use of Monte Carlo methodology

A modelagem de motores a combustão interna deve grande parte de sua importância ao uso de unidades de controle eletrônicas que buscam gerenciar as funções do motor. De forma a fornecer melhor suporte para o projetista de controle, a modelagem oferece informações que servem de planta, sobre a qual estratégias de controle serão desenvolvidas. Nesta dissertação, procurou-se estudar e modelar cinco fenômenos: a admissão de ar e de combustível, a produção de energia efetiva através da combustão, a evolução térmica do motor e o comportamento dos gases no sistema de exaustão. Investigou-se também, em todos estes fenômenos, a influência do uso de composição variada gasolina/etanol. Na admissão de ar, buscou-se estudar como a abertura da válvula borboleta e a velocidade do motor influenciam no fluxo de ar admitido, ponderando esta grandeza através de um fator de correção denominado eficiência volumétrica. Na admissão de combustível, no caso modelada para motores com injeção indireta na porta, procurou-se explanar quantitativamente sobre os diversos aspectos que influenciam a evaporação do combustível. Na geração de energia útil, priorizou-se a análise de como as características do motor e da combustão afetam a produção de torque. Na evolução térmica do motor, examinaram-se os principais fluxos energéticos do motor e os aspectos que os influenciam. Ademais, foram executadas as validações dos modelos levantados para o motor EA 111 VHT 1.6l. Os resultados, com seus respectivos erros, podem ser encontrados neste trabalho. / The internal combustion engine modeling owes big part of its importance to the use of electronic control units that aim to manage the engine functions. To provide better support to the control designer, the modeling offers information that can compose the plant, on which control strategies will be developed. In this master thesis, it was sought to study and to model five phenomena: the air intake and the fuel admission, the effective energy production from the combustion, the engine thermic evolution and the gas behavior in the exhaust system. It was also considered how the influence of the gasoline/ethanol varied composition affects all these phenomena. In the air intake, it was studied how the butterfly valve opening and the engine speed influence the intake air flow, pondering this variable through a correction factor named volumetric efficiency. In the fuel admission, in the case of this study modelled for port-fuel injection engines, it was attempted to explain quantitatively the many aspects that influence the fuel evaporation. In the mechanical energy generation, it was prioritized the analysis about how the engine and combustion characteristics affect the torque production. In the engine thermic evolution, it was examined the major energy flows and the aspects that influence them. Also, the validations of the models raised for the EA 111 VHT 1.6l engine were executed. The results, with its respective errors, can be found in this work.

Sistemas de suporte a decisão são utilizados em cenários com incertezas. Uma decisão normalmente é auxiliada por resultados obtidos com ações passadas em problemas semelhantes. Quando um sistema de suporte a decisão incorpora conhecimento específico de uma área, estes recebem o nome de sistemas especialistas. Tal conhecimento especifico é utilizado para inferência juntamente com as informações de entrada a respeito do problema. O objetivo deste trabalho é a avaliação e modelagem de sistemas de auxílio a decisão, foram analisadas duas abordagens para um mesmo problema alvo, sendo uma de gerenciamento do problema e outra de detecção do problema. A abordagem de gerenciamento utiliza redes Bayesianas para modelagem, tanto do conhecimento específico quanto para a inferência. As variáveis utilizadas, as relações de dependência e as probabilidades condicionais entre as variáveis foram extraídas da literatura. A abordagem de detecção do problema utilizou imagens para extração de características seguida de um algoritmo de agrupamento para comparação com a classificação de um especialista. Uma das áreas de aplicação de sistemas especialistas é na área clínica, podendo auxiliar tanto na detecção, diagnóstico e tratamento de doenças. A cárie dental é um problema generalizado que afeta a maioria das pessoas, tanto em países ricos, como em países pobres. Existem poucos sistemas para auxílio no processo de diagnóstico da cárie, sendo a maior parte dos sistemas existentes determinísticos, focando apenas na detecção da lesão. O sistema de gerenciamento da cárie desenvolvido foi apresentado a dois profissionais da odontologia, a opinião deles mostra que está abordagem é promissora e aplicável em campos como a educação e a atenção básica a saúde. Além da apresentação aos profissionais, foram utilizados casos bem estabelecidos da literatura para analisar as sugestões fornecidas pela Rede, e o resultado foi coerente com o cenário real de tomada de decisão. A metodologia de detecção da cárie resultou em um alto valor de acurácia, 96.88%, mostrando que tal metodologia é promissora em comparação com outros trabalhos da área. Além da contribuição para a área de informática odontológica, os resultados mostram que a extração da estrutura e das probabilidades condicionais da rede a partir da literatura é uma metodologia que pode ser utilizada em outras áreas com cenário similar ao do diagnóstico da cárie. Nos próximos passos do projeto alguns pontos referentes a modelagem de sistemas e redes Bayesianas serão analisados, como escalabilidade e testes de validação, tanto quantitativamente como qualitativamente, isto inclui o desenvolvimento de métodos computacionalmente efetivos para a geração de casos aleatórios utilizando o Método de Monte Carlo / Decision support systems are used in uncertainty scenarios; normally a decision is choose using similar problems actions results. Decision support systems could incorporate specific knowledge; such systems are called expert systems. The specific knowledge is used for inference about the problem scenario. This work objective is the evaluation and modeling of decision support systems, we analyzed two distinct approaches for the same problem, one for detection, another for management. The management approach uses Bayesian networks for modeling the specific knowledge and the inference engine. The variables choice, the dependences relationship and the conditional probabilities were extracted from the scientific literature. The detection approach used images and feature extraction to perform a clustering and compare the output labels with a specialist classification. One application of expert systems is clinical, supporting diseases detection, diagnosis and treatment. Dental caries is a generalized problem that affects major part of the population, few systems exists for support the caries diagnostic process, the major part is deterministic, focusing only the detection problem. The caries management system developed here was shown to two odontology professionals, and they opinion encourage such approach to be applied in fields like odontology education and basic health. Beyond this, we used well-established cases to analyze the network output suggestions, the result obtained was coherent with the real decision making scenario. The caries detection approach resulted in a high accuracy, 96.88%, showing that methodology is promising. Besides the contribution for dental informatics field, the results obtained here shows that the extraction of the network structure from the literature could be used in problems similar with caries diagnoses. The project next steps are to analyze some points of systems modeling and Bayesian networks, like scalability and validation tests, both quantitative and qualitative, and including the development of computational effectives methods for the use of Monte Carlo methodology

As humans, we tackle many problems in complex societies and manage the complexities of networked social systems. Cognition and sociability are two vital human capabilities that improve social life and complex social interactions. Adding these features to smart devices makes them capable of managing complex and networked Internet of Things (IoT) settings. Cognitive and social devices can improve their relationships and connections with other devices and people to better serve human needs. Nowadays, researchers are investigating two future generations of IoT: social IoT (SIoT) and cognitive IoT (CIoT). This study develops a new framework for IoT, called CSIoT, by using complexity science concepts and by integrating social and cognitive IoT concepts. This framework uses a new mechanism to leverage the friendships between devices to address service management, privacy, and security. The framework addresses network navigability, resilience, and heterogeneity between devices in IoT settings. This study uses a new simulation tool for evaluating the new CSIoT framework and evaluates the privacy-preserving ability of CSIoT using the new simulation tool. To address different CSIoT security and privacy issues, this study also proposes a blockchain-based CSIoT. The evaluation results show that CSIoT can effectively preserve the privacy and the blockchain-based CSIoT performs effectively in addressing different privacy and security issues.

This thesis is devoted to the development of new models for a recently-implemented FACTS (flexible alternating current transmission system) device, the unified power flow controller (UPFC), and the control coordination of power systems with FACTS devices in steady-state operating mode. The key objectives of the research reported in the thesis are, through online control coordination based on the models of power systems having FACTS devices, those of maximising the network operational benefit and restoring system static security following a disturbance or contingency. Based on the novel concept of interpreting the updated voltage solutions at each iteration in the Newton-Raphson (NR) power-flow analysis as dynamic variables, the thesis first develops a procedure for representing the unified power flow controllers (UPFCs) in the steady-state evaluation. Both the shunt converter and series converter control systems of a UPFC are modeled in their dynamical form with the discrete time variable replaced by the NR iterative step in the power-flow analysis. The key advantage of the model developed is that of facilitating the process of UPFC constraint resolution during the NR solution sequence. Any relative priority in control functions pre-set in the UPFC controllers is automatically represented in the power-flow formulation. Although the developed UPFC model based on the dynamic simulation of series and shunt converter controllers is flexible and general, the number of NR iterations required for convergence can be large. Therefore, the model is suitable mainly for power system planning and design studies. For online control coordination, the thesis develops the second UPFC model based on nodal voltages. The model retains all of the flexibility and generality of the dynamic simulation-based approach while the number of iterations required for solution convergence is independent of the UPFC controller dynamic responses. Drawing on the constrained optimisation based on Newton’s method together with the new UPFC model expressed in terms of nodal voltages, a systematic and general method for determining optimal reference inputs to UPFCs in steady-state operation is developed. The method is directly applicable to UPFCs operation with a high-level line optimisation control (LOC) for maximising the network operational benefit. By using a new continuation technique with adaptive parameter, the algorithm for solving the constrained optimisation problem extends substantially the region of convergence achieved with the conventional Newton’s method. Having established the foundation provided by the comprehensive models developed for representing power systems with FACTS devices including the UPFC, the research, in the second part, focuses on real-time control coordination of power system controllers, with the main purpose of restoring power system static security following a disturbance or contingency. At present, as the cost of phasor measurement units (PMUs) and wide-area communication network is on the decrease, the research proposes and develops a new secondary voltage control where voltages at all of the load nodes are directly controlled, using measured voltages.

In this thesis, dynamic modeling and nonlinear control of autonomous underwater vehicle manipulator systems are presented. Mainly, two types of systems consisting of a 6-DOF AUV equipped with a 6-DOF manipulator subsystem (UVMS) and with an 8-DOF redundant manipulator subsystem (UVRMS) are modeled considering hydrostatic forces and hydrodynamic effects such as added mass, lift, drag and side forces. The shadowing effects of the bodies on each other are introduced when computing the hydrodynamic forces. The system equations of motion are derived recursively using Newton&ndash / Euler formulation. The inverse dynamics control algorithms are formulated and trajectory tracking control of the systems is achieved by assigning separate tasks for the end effector of the manipulator and for the underwater vehicle. The proposed inverse dynamics controller utilizes the full nonlinear model of the system and consists of a linearizing control law that uses the feedback of positions and velocities of the joints and the underwater vehicle in order to cancel off the nonlinearities of the system. The PD control is applied after this complicated feedback linearization process yielding second order error dynamics. The thruster dynamics is also incorporated into the control system design. The stability analysis is performed in the presence of parametric uncertainty and disturbing ocean current. The effectiveness of the control methods are demonstrated by simulations for typical underwater missions.

In this thesis, dynamic modeling and nonlinear control of autonomous underwater vehicle manipulator systems are presented. Mainly, two types of systems consisting of a 6-DOF AUV equipped with a 6-DOF manipulator subsystem (UVMS) and with an 8-DOF redundant manipulator subsystem (UVRMS) are modeled considering hydrostatic forces and hydrodynamic effects such as added mass, lift, drag and side forces. The shadowing effects of the bodies on each other are introduced when computing the hydrodynamic forces. The system equations of motion are derived recursively using Newton&ndash / Euler formulation. The inverse dynamics control algorithms are formulated and trajectory tracking control of the systems is achieved by assigning separate tasks for the end effector of the manipulator and for the underwater vehicle. The proposed inverse dynamics controller utilizes the full nonlinear model of the system and consists of a linearizing control law that uses the feedback of positions and velocities of the joints and the underwater vehicle in order to cancel off the nonlinearities of the system. The PD control is applied after this complicated feedback linearization process yielding second order error dynamics. The thruster dynamics is also incorporated into the control system design. The stability analysis is performed in the presence of parametric uncertainty and disturbing ocean current. The effectiveness of the control methods are demonstrated by simulations for typical underwater missions.