The most widely used variable reluctance and permanent magnet stepper motors of different design types are discussed in the theoretical part of this work. It also overviews a constructional diversity of these motors, the fundamentals of operating modes and characteristics. This part discuses features of stepper motors as a part of automation control system, presents the main counting equations and applications with stepper motors. The practical part includes the mathematical model of stepper motor and the Simulink model that was developed for software package “Matlab”. Those models formed the basis for analysis of stepper motor dynamic characteristics in various operating modes (wave drive, full step drive, half step drive, microstepping, reversing, braking).

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-07-28T12:37:32Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_Doutorado_EngCivil_FMGF_2016_[digital].pdf: 9767217 bytes, checksum: e33d3971801fd7f7f68b85fc05826ba3 (MD5) / Made available in DSpace on 2016-07-28T12:37:32Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_Doutorado_EngCivil_FMGF_2016_[digital].pdf: 9767217 bytes, checksum: e33d3971801fd7f7f68b85fc05826ba3 (MD5) Previous issue date: 2016-01-29 / Ao esgotar as reservas de hidrocarbonetos em terra e águas rasas, a indústria vem explorando e produzindo petróleo em águas profundas e ultraprofundas. No entanto, a verificação hidrodinâmica de novos sistemas flutuantes de produção continua usando as metodologias consagradas, especialmente os ensaios em tanques oceânicos de laboratório. A utilização de modelos em escala reduzida vem sendo adotada desde os primeiros projetos em águas rasas e continua até hoje nos projetos em águas ultraprofundas. No entanto, os ensaios em profundidades superiores a 1.500m necessitam de um fator de escala muito elevado, com diversos problemas associados, dentre eles as dificuldades de acomodar as linhas de ancoragem e as incertezas relacionadas a modelos muito pequenos. Dentre as soluções possíveis, os ensaios híbridos (numérico-experimental) se apresentam como a solução mais viável para verificação experimental em águas ultraprofundas, em especial o ensaio híbrido passivo. Esse tipo de ensaio é organizado em etapas, sendo a primeira delas responsável pela definição do sistema truncado. Se essa etapa não for executada de forma satisfatória, o sucesso do ensaio pode ser comprometido. Assim, a fim de minimizar essa questão, propõe-se nesta tese de doutorado uma forma sistemática para encontrar sistemas truncado equivalentes, considerando os efeitos estáticos e dinâmicos, através da utilização de ferramentas de otimização. Nesse sentido, a abordagem adotada utiliza um simulador para análise estática e dinâmica de estruturas offshore denominado Dynasim e um algoritmo de otimização baseado em gradiente através do sistema Dakota. Também é utilizada a metodologia de planejamento de experimentos para identificar os fatores que influenciam as respostas estática e dinâmica do problema, evitando o uso de variáveis de projeto irrelevantes no estudo da otimização. Ressalta-se que essa metodologia não foi aplicada em outros trabalhos no contexto de sistemas de ancoragem truncado, segundo nosso conhecimento. Além disso, analisa-se o projeto ótimo do sistema truncado em várias condições ambientais, cujo interesse é verificar a concordância dele com o sistema de ancoragem na profundidade completa. Devido ao elevado custo computacional envolvido nessa verificação, utiliza-se a computação de alto desempenho, com processamento paralelo, para viabilizar a realização dessas análises. Como é demonstrado neste trabalho, a metodologia proposta facilita a busca de sistemas de ancoragem truncado equivalente preservando as características estáticas e dinâmicas do sistema de ancoragem completo. São apresentados e discutidos quatro casos, os dois primeiros se referem a casos simplificados, o terceiro é baseado na literatura e o quarto é baseado em um cenário real. Os resultados obtidos nos casos estudados mostram que os sistemas truncados equivalentes encontrados conseguem reproduzir o comportamento dos sistemas completos para as condições verificadas. / With the depletion of onshore and offshore shallow-water reserves, the industry has exploited and produced oil in deep water and ultra-deepwater. However, the hydrodynamic verification of new floating production systems continues using the established methodologies, especially by carrying out tests on ocean basin laboratories. Small-scale model tests have been used since the first projects in shallow water and continue today in the projects in ultra-deepwater. However, tests in depths above 1,500m require a very high scale factor, which poses several complications, among them the difficulties to accommodate the mooring lines and the small models related uncertainties. Among the possible solutions, the hybrid testing (numerical and experimental) are the most feasible solution to experimental verification in ultra-deepwater, especially the hybrid passive systems test. Such test is divided into steps, the first one responsible for the definition of the truncated system. If this step is not performed satisfactorily, the success of the test may be compromised. Thus, in order to minimize this issue, a systematic way to find equivalent truncated systems, considering the static and dynamic effects through the use of the optimization tools is proposed in this doctoral thesis. Accordingly, the approach adopted uses a numerical simulator, called Dynasim, for static and dynamic analysis of offshore structures, and a gradient based optimization algorithm, given in Dakota computational system. Additionally, the design of experiments methodology is used to identify the factors that influence the static and dynamic responses of the problem, avoiding the use of irrelevant design variables in the optimization process. It has to be emphasized that this methodology has not been used in other works in the context of truncated mooring systems, to our knowledge. Furthermore, the optimal design of the truncated system is analyzed for several environmental conditions. The aim is to verify the agreement of the truncated mooring system with system in the full-depth. Due to the high computational cost involved in the verification, we use the high-performance computing, with parallel computation, to perform the analyzes. As shown in this work, the proposed methodology easy the search for equivalent truncated mooring systems preserving the static and dynamic characteristics of full-depth mooring systems. Four case studies are presented and discussed. The first two refer to simplified cases; the third is based on the literature and the fourth is based on a real scenario. The results in each case show that the truncated equivalent system found can reproduce the behavior of full-depth system for the verified conditions.

Due to the emergence of new materials and advanced engineering technology, slender footbridges are increasingly becoming popular to satisfy the modern transportation needs and the aesthetical requirements of society. These structures however are always &quotlively" with low stiffness, low mass, low damping and low natural frequencies. As a consequence, they are prone to vibration induced by human activities and can suffer severe vibration serviceability problems, particularly in the lateral direction. This phenomenon has been evidenced by the excessive lateral vibration of many footbridges worldwide such as the Millennium Bridge in London and the T-Bridge in Japan. Unfortunately, present bridge design codes worldwide do not provide sufficient guidelines and information to address such vibrations problems and to ensure safety and serviceability due to the lack of knowledge on the dynamic performance of such slender vibration sensitive bridge structures. A conceptual study has been carried out to comprehensively investigate the dynamic characteristics of slender suspension footbridges under human-induced dynamic loads and a footbridge model in full size with pre-tensioned reverse profiled cables in the vertical and horizontal planes has been proposed for this purpose. A similar physical suspension bridge model was designed and constructed in the laboratory, and experimental testings have been carried out to calibrate the computer simulations. The synchronous excitation induced by walking has been modelled as crowd walking dynamic loads which consist of dynamic vertical force, dynamic lateral force and static vertical force. The dynamic behaviour under synchronous excitation is simulated by resonant vibration at the pacing rate which coincides with a natural frequency of the footbridge structure. Two structural analysis software packages, Microstran and SAP2000 have been employed in the extensive numerical analysis. Research results show that the structural stiffness and vibration properties of suspension footbridges with pre-tensioned reverse profiled cables can be adjusted by choosing different structural parameters such as cable sag, cable section and pretensions in the reverse profiled cables. Slender suspension footbridges always have four main kinds of vibration modes: lateral, torsional, vertical and longitudinal modes. The lateral and torsional modes are often combined together and become two kinds of coupled modes: coupled lateral-torsional modes and coupled torsionallateral modes. Such kind of slender footbridges also have different dynamic performance in the lateral and vertical directions, and damping has only a small effect on the lateral vibration but significant effect on the vertical one. The fundamental coupled lateral-torsional mode and vertical mode are easily excited when crowd walking dynamic loads are distributed on full bridge deck. When the crowd walking dynamic loads are distributed eccentrically on half width of the deck, the fundamental coupled torsional-lateral mode can be excited and large lateral deflection can be induced. Higher order vertical modes and coupled lateral-torsional modes can also be excited by groups of walking pedestrians under certain conditions. It is found that the coupling coefficient introduced in this thesis to describe the coupling of a coupled mode, is an important factor which has significant effect on the lateral dynamic performance of slender suspension footbridges. The coupling coefficient, however, is influenced by many structural parameters such as cable configuration, cable section, cable sag, bridge span and pre-tensions, etc. In general, a large dynamic amplification factor is expected when the fundamental mode of a footbridge structure is the coupled lateral-torsional mode with a small coupling coefficient. The research findings of this thesis are useful in understanding the complex dynamic behaviour of slender and vibration sensitive suspension footbridges under humaninduced dynamic loads. They are also helpful in developing design guidance and techniques to improve the dynamic performance of such slender vibration sensitive footbridges and similar structures and hence to ensure their safety and serviceability.

This master´s thesis provides an overview of all designs of check valves, their usage and typical features. Main purpose of this work is to clear up the phenomenon of check valve slam and the other problems that occur during transients. The check valve slam was measured at the test rig in the hydraulic laboratory. For unsteady flow evaluation after pump shut down was used Gibson method. The dynamic characteristic was possible to create by results from this method. It was achieved without impact of the speed of sound in the fluid. This work also contains 2D transient CFD calculations, which was used for evaluation of the hydrodynamic torque acting on the hinge pin. This approach provides an option to calculate wide range of cases at the expense of not entirely exact geometry. The main contribution of the theoretical study at the beginning of this thesis is its entireness. It might give an important clue when right valve is selecting. For good choice of valve might be helpful to use dynamic characteristics in this thesis presented. Mentioned characteristics were created by new way and its background is in measurements and simplified CFD calculations.