As the light source, semiconductor laser diodes play an important role in the fiber-optic communication systems. The main function of a laser diode is to convert signals from the electrical domain to the optical carriers so that they can be transmitted through an optical fiber. Modeling and simulation of directly modulated laser diodes are necessary for understanding and prediction of their performance in fiber-optical communication links. The alternatives based on a comprehensive experimental evaluation are normally costly and time consuming. This is particularly true for systems running at high bit-rate such as the 10Gb/s transmission systems that are used in tele and data communication applications. This thesis presents a modeling and simulation study for directly modulated laser diodes for high-speed fiber-optical communication systems. The work is based on the conventional rate equation model used as the governing equation for the simulation of the behavior of semiconductor lasers. In modeling of the system performance, each device is treated as a symbolic node that takes input signal and generates output signal all in time domain. For the semiconductor lasers, the original signals in electrical domain are taken as the input while the modulated lights in optical domain are as the output. The rate equations then link the output to the input. For any given time domain signal input, the modulated light (power and wavelength) as the output is calculated through the solutions of the rate equations. In seeking for the solution to the rate equations, we utilized a numerical approach to solve the rate equations which are a system of coupled nonlinear ordinary differential equations where analytical solution does not generally exist. In this work, a comprehensive study on the behavior of semiconductor lasers has been performed through static and dynamic analyses of the rate equations. The noise characteristic is also examined as it may become a major concern in some applications for the noise of the directly modulated laser transmitter may cause degradation to the signals and therefore lead to system penalty. Further, the numerical models and simulators developed for semiconductor lasers are incorporated into a general simulation platform on which similar models and simulators for other optoelectronic and optical components are connected to form a system-level simulator for point-to-point multiple channel fiber-optical communication links. This platform is capable of handling different system configurations with different component selection options. It simulates the time domain waveform in any point along the signal transmission path following a strict data-flow approach; i.e., the simulation is performed sample-by-sample on “real time” rather than frame-by-frame at “flush” mode. Finally, the simulation results, both on the device level and on the system level, have been compared with the experimental data and the results from other models in literature and found qualitative agreement. / Thesis / Master of Applied Science (MASc)

<p dir="ltr">To establish a long-term human presence on the Moon, it is necessary to have habitat systems that function effectively under challenging conditions and have sufficient autonomous technologies for fault detection and intervention. However, evaluating these habitats presents challenges due to their pervasive interdependencies and the harsh environmental conditions they must withstand. Thus, innovative testing techniques are vital to understanding and capturing the complexities these systems will encounter. </p><p dir="ltr">Thermomechanical real-time hybrid simulation (RTHS) provides unique opportunities to observe realistic behaviors and interdependencies, train models, test ideas, and validate methods. It is a cost-effective and accessible cyber-physical testing method that allows for the simultaneous experimental and computational modeling of systems, offering a comprehensive observation of their behavior under extreme dynamic conditions. This dissertation presents the development and experimental validation of a novel thermomechanical RTHS method to assess the multi-physics response of lunar habitat systems due to disruptive events. It outlines the conceptual framework, modeling approaches, and experimental considerations crucial to establishing the two-way coupling between a numerical and a physical subsystem through an innovative thermal transfer system. </p><p dir="ltr">The thermal transfer system utilizes a thermal actuator to impose distributed thermal loads on the experimental subsystem. The thermal actuator is identified considering switching-mode continuous dynamics for cooling and heating conditions. A switching control system is then developed to experimentally enforce the desired thermal conditions across different thermal cycles with minimum tracking error, adjusting the gains of the controller in response to varying temperature conditions. Furthermore, this dissertation demonstrates how to establish control and performance requirements for RTHS methods to effectively evaluate the realization of interface boundary conditions and determine acceptance criteria to perform RTHS tests with high confidence. </p><p dir="ltr">The RTHS method is experimentally implemented and validated through a series of scenario tests that simulate the cascading thermomechanical effects on a lunar habitat after a micrometeorite impact that damages its structural protective layer. These realistic tests aim to evaluate fault detection and decision-making methods in response to such disruptive events. Thus, using switching dynamic modeling, the RTHS problem formulation is designed to have numerical damage and repair capabilities, allowing interaction with these fault detection and intervention methods. The scenario results obtained through thermomechanical RTHS reveal behaviors and interactions that are not captured through purely numerical simulation or traditional experimental approaches. Through the experimental implementation of these scenario case studies, the thermomechanical RTHS method developed is the first of its kind to experimentally execute the effects of damage and repair intervention strategies in real-time on a numerical subsystem while simultaneously imposing the cascading effects on a physical specimen. </p><p dir="ltr">The findings of this dissertation advance our knowledge and offer insights into developing cost-effective and accessible cyber-physical methods to test novel ideas and technologies, thereby empowering and supporting space resilience and autonomy research. </p>

A produção de petróleo e gás em campos brasileiros é cada vez mais proveniente de regiões com águas profundas e situadas longe da costa, chegando a distâncias de mais de 100 km, como, por exemplo, na Bacia de Campos ou de Santos. Devido à falta de infra-estrutura e às características do petróleo desses campos, a cadeia de abastecimento e o sistema de exportação da produção possuem grande importância para a indústria offshore. Uma maneira usual para a exportação da produção é através de dutos submarinos, onde o óleo e/ou a gás flui das plataformas diretamente para o continente. Com esta infra-estrutura é possível a utilização de sistemas de produção sem capacidade de armazenamento e, conseqüentemente, torna-se desnecessário o uso de navios para o alívio da produção. No entanto, devido à qualidade do óleo e às distâncias entre os poços e a costa em alguns campos brasileiros, a utilização dos oleodutos mostra-se uma solução pouco viável. Por este motivo, é bastante comum o uso de FPSOs ou semi-submersíveis conectadas a sistemas auxiliares, como o FSO (Floating Storage and Offloading). Nas plataformas, outra característica importante e desejada é tornar viável o uso de um sistema de completação seca (árvore de Natal acima da linha dágua) com o objetivo de diminuir, significativamente, os custos operacionais envolvidos. Esse tipo de completação é utilizado, com excelência, por unidade do tipo TLWP ou Spar, devido ao baixo nível dos movimentos e acelerações observadas nestas plataformas. Entretanto, as condições ambientais severas amplificam as dificuldades para encontrar um sistema com grande capacidade de armazenamento e que permita o uso de completação seca. Neste contexto, pesquisadores e engenheiros estão sendo obrigados a desenvolver novos conceitos capazes de atender a essa demanda. Desta forma, uma nova solução, considerando um FPSO e uma TLWP operando a uma curta distância e trabalhando de forma acoplada com a conexão garantida por cabos sintéticos vem sendo estudada. Essencialmente, o grande atrativo deste conceito é o fato de que toda a produção e o armazenamento são concentrados no FPSO e a TLWP é responsável pela perfuração e extração dos hidrocarbonetos através de risers verticais. Assim o sistema trabalhando de forma conjunta possui capacidade de armazenamento e permite o uso da completação seca. Nesta dissertação, foi realizado um estudo sobre a evolução deste novo conceito, dividido em três fases. A primeira focada no dimensionamento do sistema de conexão e ancoragem das unidades e em uma investigação da interação hidrodinâmica entre as unidades de forma a mostrar a viabilidade do sistema. A segunda fase, focada na validação dos resultados por meio da comparação com os testes realizados no modelo em escala do NMRI (National Maritime Research Institute - Japão). Finalmente, a terceira fase, com foco no redimensionamento do sistema de amarração e no sistema de conexão, com base nos resultados obtidos na segunda fase. / The oil and gas production in Brazilian fields are commonly found in deep water and situated far away from the coast, reaching distances of more than 100 km as, for example, in the Campos Basin or Santos Basin. Due to the heavy oil and lack of pipeline infrastructure found in these fields, not only subsea equipments that must support high pressure but also logistics problems such as supply chain and production exportation system play an important role for the offshore industry. A usual way to export the production is to concentrate it in hubs of submarine pipelines which flows the oil or gas from the platforms to the continent. This infrastructure makes possible the use of no storage production systems and, consequently, releases the use of the shuttle tanks employment. However, due to the quality of the oil and the distances between the wells and the coast, some Brazilian fields do not allow the use of the pipelines to export their production. For this reason, is quite common to use FPSO and semi-submersible aided by auxiliary systems such as the FSO (Floating Storage and Offloading) units. Another important and desired characteristic of production platforms is to make it feasible to install a dry Christmas tree system aiming to decrease, significantly, operational costs involved. This feature is performed, with excellence, by TLWP and Spar units due to the low level of motions and accelerations observed in these platforms. Harsh environmental conditions can bring difficulties to find a solution of a system with both storage and dry tree system capability. In this context, researchers and engineers are being forced to develop new technological systems capable to support this demand. In this way, a new solution considering a FPSO and a TLWP coupled in a short distance by synthetic ropes has being studied. Essentially, the attractive feature of this concept is the fact that the production is performed by the FPSO whereas the TLWP is responsible to support the risers and drilling facilities turning the system coupled, equipped with a dry Christmas tree and with the possibility to storage the production. By now, the concept evolution has been divided in three phases. The first phase concerned about an advanced research focusing on the connection and mooring system development and the hydrodynamic interaction between the units and having in mind the verification of the concept feasibility. The second phase, concerned about the results validation by a comparison with scale model tests performed in the NMRI (National Maritime Research Institute Japan). Finally, the third phase, has the focus in the mooring and connection system resizing based on the results obtained on second phase.

[pt] Os sistemas de energia elétrica estão operando atualmente próximos dos limites de estabilidade, comprometendo a segurança. Este fato tem sido evidenciado por diversos blackouts no mundo inteiro. A avaliação da segurança dinâmica torna-se, então, fundamental. O objetivo é a busca de um método rápido e, sobretudo, confiável, para analisar o comportamento dinâmico de um sistema de energia elétrica. Esta dissertação trata, portanto, do problema da avaliação da segurança dinâmica de sistemas de energia elétrica. A avaliação é realizada através da determinação das margens de estabilidade, utilizando os resultados de simulações no domínio do tempo, que fornece informações qualitativas a respeito da estabilidade na primeira oscilação. O grupo de geradores severamente perturbados é determinado e a margem de estabilidade de cada um deles é calculada. O gerador que apresentar a menor margem determina a margem de estabilidade do sistema. Quando a margem de estabilidade assume valor nulo, o tempo crítico de eliminação da falta é obtido. Estes resultados são comparados com aqueles determinados pelo método de tentativa e erro, utilizando um programa convencional de estabilidade transitória. Desta forma, as contingências são classificadas em função dos tempos críticos de eliminação de falta, de acordo com o nível de severidade. Essa classificação permite reduzir o conjunto de contingências a ser estudado. A contribuição deste trabalho é mostrar que o critério baseado na aceleração imediatamente após a eliminação da falta é mais eficaz que aquele baseado na aceleração imediatamente após a ocorrência da falta para a indicação do grupo de geradores severamente perturbados. / [en] Power systems have been operating nowadays near to the stability limits putting security under risk. This is one of the reasons why the dynamic security assessment is a fundamental tool to avoid the occurrence of blackouts in the whole world. The goal is a reliable and fast way to evaluate the dynamic behavior of a power system. This dissertation deals with the problem of dynamic security assessment of power systems. The evaluation is performed based on stability margins calculated from time domain simulation results, providing qualitative information about the first swing stability. The group of severely disturbed machines is defined and the stability margins are determined. The machine with the lowest margin determines the stability margin of the system. When the system margin approaches the zero value, the critical clearing time is obtained. These outcomes are compared with that ones determined by trial and error method using a conventional transient stability program. Having done that, a contingency ranking is defined according to the critical clearing time. The ranking minimizes the number of contingencies that have to be studied. This dissertation shows that the criterion to define the group of severely disturbed machines based on the machine accelerations at the instant immediately after the fault clearing time is more efficient than that one based on the machine accelerations at the instant immediately after the fault occurrence.

[pt] O problema tratado nesta dissertação é a relação oposta entre a tensão de excitação de geradores e compensadores síncronos e a tensão controlada, quando o sistema de transmissão da área encontra-se muito carregado. Neste caso, a capacidade nominal de um gerador / compensador não seria útil para manter a tensão controlada. Devido à relação oposta, uma maior excitação da máquina iria abaixar a tensão controlada. O controle automático iria continuar agindo, abaixando ainda mais a tensão. Este mecanismo pode levar o sistema ao colapso e foi verificado em ponto de operação real do sistema brasileiro. Esse fenômeno ocorre quando a injeção de potência na rede de transmissão ou distribuição é elevada. Com o advento da geração distribuída, co-geração e produtores independentes, usualmente conectados à rede existente em níveis de tensão mais baixas, têm-se observado ocorrências do fenômeno. O objetivo do trabalho é então entender melhor as situações operativas reais que levam à ocorrência do fenômeno, principalmente quando existem vários equipamentos de controle de tensão ao redor do gerador em análise. A abordagem do problema baseou-se na verificação do comportamento do gerador / compensador como dispositivo de controle de tensão, no domínio do tempo e em regime permanente. Avaliaram-se as ações de controle do mesmo a partir de sete tipos de análise distintas para pontos de operação na região normal e anormal da curva SV. A real existência do fenômeno foi comprovada através de algumas destas análises. Porém, conclui-se que nem todas as formas de análise no domínio do tempo fazem uma avaliação completa do fenômeno. Dentre essas, estão a análise dinâmica agregada e a análise dinâmica agregada sob influência dos equipamentos de controle de tensão, que para pontos de operação na região anormal da curva SV não responderam em concordância com os outros tipos de análise. / [en] The problem addressed in this research is the opposite relationship between the , synchronous generator / compensator excitation voltage and the controlled voltage when nearby network is heavily loaded. In this situation, the nominal capacity of a generator / compensator would not keep the voltage controlled. Due to the opposite relationship, the higher the excitation voltage the lower is the controlled voltage. So, the automatic control would continue acting lowering the voltage. This mechanism, verified in a real operational point of the Brazilian Electric System, can lead the system to collapse. This phenomenon occurs when the power injection into the network is high. It is prone to occur in the new scenario of distributed generation connected to already existing low voltage networks. The objective of this work is to understand the actual operative situations that lead to the occurrence of the phenomenon, mainly when there are several voltage control devices nearby the generator. The analysis of the problem was based on the verification of the generator behaviour as a voltage control device, in time domain simulation and in steady state. The control actions were evaluated from seven different ways for operating points in the normal and the abnormal region of the SV curve. The actual existence of the phenomenon was proven through some of these analyses. However, some of the time domain simulations did not evaluated the phenomenon completely. Among them, the aggregated dynamic analysis and the aggregated dynamic analysis under influence of other voltage control devices have not got the expected responses for the abnormal region of the SV curve, in comparison with other analysis.

This thesis advances the state of the art in modeling electric machines in electro-magnetic transient simulation programs, particularly in real-time digital simulators. A new tool, developed in this thesis, expands the application of real-time digital simulators to closed-loop testing of protection relays designed to protect synchronous machines during internal faults. To evaluate the inductances of synchronous machines, a winding function approach was developed in this thesis which is capable of taking into account both the actual distribution of windings and the shape of the pole-arc. Factors such as MMF drop in the iron and effects of slots are compensated by evaluating the effective permeance function of the machine using experimentally measured values of d-, q- and 0- axis inductances. In this winding function approach, the effects of magnetic saturation are also included by considering the actual distribution of magneto-motive force in each loading condition of the machine. The inductances of an experimental machine are evaluated using this approach and validated using the finite-element method and laboratory measurements. This thesis also proposes an embedded phase-domain approach for time-domain simulation of the machine model in electromagnetic transients programs. The approach significantly improves the numerical stability of the simulations. Special numerical techniques are introduced, which speed up the execution of the algorithm as needed for real-time simulation. The machine model is validated in healthy and faulted conditions using simulations and laboratory experiments. Effects of damper grid representation on simulating turn-to-turn faults are investigated. The capability of this new real-time synchronous machine model in closed-loop testing of synchronous machines ground- faults protection relays is clearly demonstrated.

In 2000, a controversial paper by John Pendry surmised that a slab of negative index material could act as a perfect lens, projecting images with resolution detail beyond the limits of conventional lensing systems. A thin silver slab was his realistic suggestion for a practical near-field superlens - a 'poor-mans perfect lens'. The superlens relied on plasmonic resonances rather than negative refraction to provide imaging. This silver superlens concept was experimentally verified by the author using a novel near-field lithographic technique called Planar Lensing Lithography (PLL), an extension of a previously developed Evanescent Near-Field Optical Lithography (ENFOL) technique. This thesis covers the computational and experimental efforts to test the performance of a silver superlens using PLL, and to compare it with the results produced by ENFOL. The PLL process was developed by creating metal patterned conformable photomasks on glass coverslips and adapting them for use with an available optical exposure system. After sub-diffraction-limited ENFOL results were achieved with this system additional spacer and silver layers were deposited onto the masks to produce a near-field test platform for the silver superlens. Imaging through a silver superlens was achieved in a near-field lithography environment for sub-micron, sub-wavelength, and sub-diffraction-limited features. The performance of PLL masks with 120-, 85-, 60-, and 50-nm thick silver layers was investigated. Features on periods down to 145-nm have been imaged through a 50-nm thick silver layer into a thin photoresist using a broadband mercury arc lamp. The quality of the imaging has been improved by using 365 nm narrowband exposures, however, resolution enhancement was not achieved. Multiple layer silver superlensing has also been experimentally investigated for the first time; it was proposed that a multi-layered superlens could achieve better resolution than a single layer lens for the same total silver thickness. Using a PLL mask with two 30-nm thick silver layers gave 170-nm pitch sub-diffraction-limited resolution, while for a single layer mask with the same total thickness (60 nm) resolution was limited to a 350-nm pitch. The proposed resolution enhancement was verified, however pattern fidelity was reduced, the result of additional surface roughness. Simulation and analytical techniques have been used to investigate and understand vi ABSTRACT the enhancements and limitations of the PLL technique. A Finite-Difference Time- Domain (FDTD) tool was written to produce full-vector numerical simulations and this provided both broad- and narrowband results, allowing image quality as a function of grating period to be investigated. An analytical T-matrix method was also derived to facilitate computationally efficient performance analysis for grating transmission through PLL stacks. Both methods showed that there is a performance advantage for PLL over conventional near-field optical lithography, however, the performance of the system varies greatly with grating period. The advantages of PLL are most prominent for multi-layer lenses. The work of this thesis indicates that the utilisation of plasmonic resonances in PLL and related techniques can enhance the performance of near-field lithography.

This thesis advances the state of the art in modeling electric machines in electro-magnetic transient simulation programs, particularly in real-time digital simulators. A new tool, developed in this thesis, expands the application of real-time digital simulators to closed-loop testing of protection relays designed to protect synchronous machines during internal faults. To evaluate the inductances of synchronous machines, a winding function approach was developed in this thesis which is capable of taking into account both the actual distribution of windings and the shape of the pole-arc. Factors such as MMF drop in the iron and effects of slots are compensated by evaluating the effective permeance function of the machine using experimentally measured values of d-, q- and 0- axis inductances. In this winding function approach, the effects of magnetic saturation are also included by considering the actual distribution of magneto-motive force in each loading condition of the machine. The inductances of an experimental machine are evaluated using this approach and validated using the finite-element method and laboratory measurements. This thesis also proposes an embedded phase-domain approach for time-domain simulation of the machine model in electromagnetic transients programs. The approach significantly improves the numerical stability of the simulations. Special numerical techniques are introduced, which speed up the execution of the algorithm as needed for real-time simulation. The machine model is validated in healthy and faulted conditions using simulations and laboratory experiments. Effects of damper grid representation on simulating turn-to-turn faults are investigated. The capability of this new real-time synchronous machine model in closed-loop testing of synchronous machines ground- faults protection relays is clearly demonstrated.

A produção de petróleo e gás em campos brasileiros é cada vez mais proveniente de regiões com águas profundas e situadas longe da costa, chegando a distâncias de mais de 100 km, como, por exemplo, na Bacia de Campos ou de Santos. Devido à falta de infra-estrutura e às características do petróleo desses campos, a cadeia de abastecimento e o sistema de exportação da produção possuem grande importância para a indústria offshore. Uma maneira usual para a exportação da produção é através de dutos submarinos, onde o óleo e/ou a gás flui das plataformas diretamente para o continente. Com esta infra-estrutura é possível a utilização de sistemas de produção sem capacidade de armazenamento e, conseqüentemente, torna-se desnecessário o uso de navios para o alívio da produção. No entanto, devido à qualidade do óleo e às distâncias entre os poços e a costa em alguns campos brasileiros, a utilização dos oleodutos mostra-se uma solução pouco viável. Por este motivo, é bastante comum o uso de FPSOs ou semi-submersíveis conectadas a sistemas auxiliares, como o FSO (Floating Storage and Offloading). Nas plataformas, outra característica importante e desejada é tornar viável o uso de um sistema de completação seca (árvore de Natal acima da linha dágua) com o objetivo de diminuir, significativamente, os custos operacionais envolvidos. Esse tipo de completação é utilizado, com excelência, por unidade do tipo TLWP ou Spar, devido ao baixo nível dos movimentos e acelerações observadas nestas plataformas. Entretanto, as condições ambientais severas amplificam as dificuldades para encontrar um sistema com grande capacidade de armazenamento e que permita o uso de completação seca. Neste contexto, pesquisadores e engenheiros estão sendo obrigados a desenvolver novos conceitos capazes de atender a essa demanda. Desta forma, uma nova solução, considerando um FPSO e uma TLWP operando a uma curta distância e trabalhando de forma acoplada com a conexão garantida por cabos sintéticos vem sendo estudada. Essencialmente, o grande atrativo deste conceito é o fato de que toda a produção e o armazenamento são concentrados no FPSO e a TLWP é responsável pela perfuração e extração dos hidrocarbonetos através de risers verticais. Assim o sistema trabalhando de forma conjunta possui capacidade de armazenamento e permite o uso da completação seca. Nesta dissertação, foi realizado um estudo sobre a evolução deste novo conceito, dividido em três fases. A primeira focada no dimensionamento do sistema de conexão e ancoragem das unidades e em uma investigação da interação hidrodinâmica entre as unidades de forma a mostrar a viabilidade do sistema. A segunda fase, focada na validação dos resultados por meio da comparação com os testes realizados no modelo em escala do NMRI (National Maritime Research Institute - Japão). Finalmente, a terceira fase, com foco no redimensionamento do sistema de amarração e no sistema de conexão, com base nos resultados obtidos na segunda fase. / The oil and gas production in Brazilian fields are commonly found in deep water and situated far away from the coast, reaching distances of more than 100 km as, for example, in the Campos Basin or Santos Basin. Due to the heavy oil and lack of pipeline infrastructure found in these fields, not only subsea equipments that must support high pressure but also logistics problems such as supply chain and production exportation system play an important role for the offshore industry. A usual way to export the production is to concentrate it in hubs of submarine pipelines which flows the oil or gas from the platforms to the continent. This infrastructure makes possible the use of no storage production systems and, consequently, releases the use of the shuttle tanks employment. However, due to the quality of the oil and the distances between the wells and the coast, some Brazilian fields do not allow the use of the pipelines to export their production. For this reason, is quite common to use FPSO and semi-submersible aided by auxiliary systems such as the FSO (Floating Storage and Offloading) units. Another important and desired characteristic of production platforms is to make it feasible to install a dry Christmas tree system aiming to decrease, significantly, operational costs involved. This feature is performed, with excellence, by TLWP and Spar units due to the low level of motions and accelerations observed in these platforms. Harsh environmental conditions can bring difficulties to find a solution of a system with both storage and dry tree system capability. In this context, researchers and engineers are being forced to develop new technological systems capable to support this demand. In this way, a new solution considering a FPSO and a TLWP coupled in a short distance by synthetic ropes has being studied. Essentially, the attractive feature of this concept is the fact that the production is performed by the FPSO whereas the TLWP is responsible to support the risers and drilling facilities turning the system coupled, equipped with a dry Christmas tree and with the possibility to storage the production. By now, the concept evolution has been divided in three phases. The first phase concerned about an advanced research focusing on the connection and mooring system development and the hydrodynamic interaction between the units and having in mind the verification of the concept feasibility. The second phase, concerned about the results validation by a comparison with scale model tests performed in the NMRI (National Maritime Research Institute Japan). Finally, the third phase, has the focus in the mooring and connection system resizing based on the results obtained on second phase.

The doctoral thesis is focused on reliability of lead-free solder SAC 305. Knowledge in the field of fatigue models used in determining the lifetime of solder joints are observed in this thesis. Also such methods of predicting reliability as numerically-analytical methods or reliability experimental tests are mentioned. Practical results of reliability measurement are presented. Experimental data served as the foundation for determining empirical coefficients for the fatigue model based on deformation induced by creep of the solder, which was implemented in the ANSYS environment. Results from different methods were compared and conclusions discussing the suitability of the presented prediction methods are formulated.