In this thesis the characteristics of pitch and roll damping coefficients of missile models are investigated by using Computational Fluid Dynamics (CFD) techniques. Experimental data of NACA0012 airfoil, Basic Finner (BF) and Modified Basic Finner (MBF) models are used for validation and verification studies. Numerical computations are performed from subsonic to supersonic flow regimes. Grid refinement and turbulence model selection studies are conducted before starting the dynamic motion simulations. Numerical method of dynamic motion simulation is validated with a 2D NACA0012 airfoil. After the validation of numerical method, forced-oscillation motion is given to the BF and MBF models. In order to get deeper understandings about the characteristics of dynamic pitching and rolling motions, parametric studies are performed. The amplitude and frequency of forced-oscillation motions are investigated one by one. The effects of angle of attacks are also investigated for both pitching and rolling motions. The results of CFD simulations are compared with experimental data obtained from different wind tunnel and free flight tests. It is seen from these comparisons that experimental and numerical results are in good agreement throughout the whole flow regime. In conclusion, the numerical method presented in this study is validated and can be used for the prediction of pitch and roll damping coefficient of any missile configurations.

O crescimento da demanda de energia e das interligações entre os Sistemas Elétricos de Potência, assim como a necessidade de prestação de melhores serviços exigem que as técnicas de análise destes sejam cada vez mais rápidas e refinadas. Dentre estas técnicas, as análises de estabilidade transitória através de métodos energéticos são estudadas e o desenvolvimento de técnicas computacionais que permitam a análise em tempo real da estabilidade transitória é o principal objetivo deste trabalho. Os métodos energéticos são métodos diretos adequados à aplicações em tempo real, pois obtém informações a respeito da estabilidade diretamente das equações diferenciais do sistema, sem a necessidade do conhecimento das soluções das equações diferenciais. A aplicação de métodos energéticos aos estudos de estabilidade transitória evoluiu significativamente nos últimos anos. Esta evolução culminou com o desenvolvimento do método BCU. Este método está fundamentado no conceito de ponto de equilíbrio de controle e portanto, garante apenas a existência ou a estabilidade do primeiro \"swing\". Embora este seja um método eficiente, existe uma grande quantidade de casos que são estáveis no primeiro \"swing\", mas o sistema perde a estabilidade em \"swings\" subseqüentes. Para resolver este problema, desenvolveu-se uma técnica de estimativa do parâmetro amortecimento para o caso de uma máquina versus barramento infinito. Estima-se o amortecimento necessário que a máquina deverá possuir tal que a estabilidade nos \"swings\" subseqüentes seja garantida. Esta metodologia é utilizada em conjunto com o BCU garantindo a satisfação da condição de transversalidade exigida no desenvolvimento teórico deste método. Maiores investigações serão necessárias para estimar os amortecimentos em sistemas multimáquinas. / The increase of load demand and interconnection between power systems as well as the necessity of offering better customer services require fast and refined techniques to analyze these systems. In particular, the transient stability analysis is studied and the development of computational techniques suitable to real-time transient stability analysis is the main aim of this work. The energetic methods are direct methods suitable to real-time applications because they obtain qualitative information about the system without the knowledge of the differential equation solutions. The application of energetic methods to the transient stability analysis developed significantly in the last years. This evolution culminated with the development of the BCU method. This method is based on the concept of controlling equilibrium point, therefore it only guarantees the existence of the first swing. In spite of the efficiency of this method, there exists a high number of cases where the BCU predicts stability to the first swing but the system becomes unstable or loses synchronism in future swings. In order to solve this problem, a methodology to estimate the damping coefficient was developed to the machine versus infinite bus case. The damping coefficient that must be applied to the machine to guarantee the stability in future swings is estimated. This methodology is used together with the BCU method guaranteeing the satisfying of the transversality condition required by the BCU theory. Further investigations must be carried out to extend the methodology to multimachine systems.

O crescimento da demanda de energia e das interligações entre os Sistemas Elétricos de Potência, assim como a necessidade de prestação de melhores serviços exigem que as técnicas de análise destes sejam cada vez mais rápidas e refinadas. Dentre estas técnicas, as análises de estabilidade transitória através de métodos energéticos são estudadas e o desenvolvimento de técnicas computacionais que permitam a análise em tempo real da estabilidade transitória é o principal objetivo deste trabalho. Os métodos energéticos são métodos diretos adequados à aplicações em tempo real, pois obtém informações a respeito da estabilidade diretamente das equações diferenciais do sistema, sem a necessidade do conhecimento das soluções das equações diferenciais. A aplicação de métodos energéticos aos estudos de estabilidade transitória evoluiu significativamente nos últimos anos. Esta evolução culminou com o desenvolvimento do método BCU. Este método está fundamentado no conceito de ponto de equilíbrio de controle e portanto, garante apenas a existência ou a estabilidade do primeiro \"swing\". Embora este seja um método eficiente, existe uma grande quantidade de casos que são estáveis no primeiro \"swing\", mas o sistema perde a estabilidade em \"swings\" subseqüentes. Para resolver este problema, desenvolveu-se uma técnica de estimativa do parâmetro amortecimento para o caso de uma máquina versus barramento infinito. Estima-se o amortecimento necessário que a máquina deverá possuir tal que a estabilidade nos \"swings\" subseqüentes seja garantida. Esta metodologia é utilizada em conjunto com o BCU garantindo a satisfação da condição de transversalidade exigida no desenvolvimento teórico deste método. Maiores investigações serão necessárias para estimar os amortecimentos em sistemas multimáquinas. / The increase of load demand and interconnection between power systems as well as the necessity of offering better customer services require fast and refined techniques to analyze these systems. In particular, the transient stability analysis is studied and the development of computational techniques suitable to real-time transient stability analysis is the main aim of this work. The energetic methods are direct methods suitable to real-time applications because they obtain qualitative information about the system without the knowledge of the differential equation solutions. The application of energetic methods to the transient stability analysis developed significantly in the last years. This evolution culminated with the development of the BCU method. This method is based on the concept of controlling equilibrium point, therefore it only guarantees the existence of the first swing. In spite of the efficiency of this method, there exists a high number of cases where the BCU predicts stability to the first swing but the system becomes unstable or loses synchronism in future swings. In order to solve this problem, a methodology to estimate the damping coefficient was developed to the machine versus infinite bus case. The damping coefficient that must be applied to the machine to guarantee the stability in future swings is estimated. This methodology is used together with the BCU method guaranteeing the satisfying of the transversality condition required by the BCU theory. Further investigations must be carried out to extend the methodology to multimachine systems.

In this study, a small-scale point absorber wave energy converter has been designed contemplating a full-scaled point absorber in the Mediterranean Sea state. The scaling factor for the small-scaled version has been determined by the damping coefficient calculation of the power take-off in 1:10, 1:15, and 1:20 scaling factors. Here a rotational power take-off has been designed instead of the linear one. The rotational power take-off will follow a similar principle as the Eddy current brake. The effect of change in the radius of the translator and magnetic flux in the damping coefficient had been calculated as well. The calculation for the damping coefficient has been conducted in COMSOL Multiphysics. The design for the point absorber was assembled in SolidWorks. In this article, specific attention is given to a variety of aspects affecting the damping coefficient and the way it can aid to determining the scaling factor parameters for a small-scale wave energy converter.

No description available.

Despite advancements in the analysis of statnamic load testing data, there exists uncertainty with underlying procedural assumptions. Two such assumptions are that the system mass and soil-related damping coefficient remain constant throughout the loading event. These assumptions are the culprit of aberrant predictions of the static capacity at small displacements when the overall displacement is large. An exploration of the assumptions may validate prior existing test results as well as solidify the current analysis process. However, an exploration could also reveal an overestimation or underestimation of portions of the predicted static load responses. The testing program outlined herein consists of a two-phase sequential agenda devoted toward the preparation and familiarization of a new laboratory statnamic device. The first phase involves the development of user guidelines for accurately targeting a desired statnamic test, and the second incorporates the guidelines into a preliminary testing regime specifically targeted at determining a suspected strain-dependant statnamic damping coefficient. The steps taken in this thesis are intended to launch future research endeavors toward obtaining a better understanding of the statnamic damping coefficient.

No description available.

Wave energy converter (WEC) harnesses energy from the ocean to produce electrical power. The electrical power produced by the WEC is fluctuating and is not maximized as well, due to the varying ocean conditions. As a consequence, without any intermediate power conversion stage, the output power from the WEC can not be fed into the grid. To feed WEC output power into the grid, a two-stage power conversion topology is used, where the WEC output power is first converted into DCpower through rectification, and then a DC-AC converter (inverter) is used to supply AC power into the grid. The main motive of this research is to extract maximum electrical power from the WEC by active rectification and smoothing the power fluctuation of the wave energy converter through a hybrid energy storage system consisting of battery and flywheel. This research also illustrates active and reactive power injection to the grid according to load demand through a voltage source inverter.