Search

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.

U radu su prikazani upravljanje i regulacija sustava na primjeru regulacije temperature na maketi. Na ovom jednostavnom i relativnom sporom procesu pokazat će se snimanje statičkih i dinamičkih karakteristika sustava te odziva regulatora. Na temelju dinamičke karakteristike provest će se identifikacija sustava, a promatranjem odziva različitih regulatora pokazati će se njihovi prednosti i nedostatci. Sustav se sastoji od triju glavnih komponenti: makete, mikrokontrolera i računalnog programa (aplikacije). Maketa i mikrokontroler dobiveni su kao cjeloviti sklopovi te je mikrokontroler dobiven programiran kao upravljačka jedinica. Računalni program (aplikacija) je jedina komponenta koja je razvijena od nule. In this paper system regulation and control is presented on example of mock up temperature control. On this simple and relatively slow process static and dynamic characteristics will be recorded, also system response of various regulators will be shown. On the basis of systems dynamic characteristic system identification will be carried out, also by observing the response of the various regulators their advantages and disadvantages will be shown. The system consists of three main components: mock up, microcontroller and computer program (application). Mock up and the microcontroller for the purposes of this paper were given as completed circuits, also microcontroller was programmed as control unit. A computer program is the only component that has been developed from scratch.

Buçalışmada elektromekanik supap mekanizmalarında kullanılabilecek uygun manyetikdevre tipleri incelenmiştir. Disk tipi manyetik devreye elektromekanik supapmekanizması iki farklı tipte tasarlanmış ve yay sabiti, kütle, besleme gerilimive tutma akımı gibi çeşitli tasarım parametrelerinin sistem üzerindeki etkileriincelenmiştir. Sistemin statik ve dinamik denklemleri çıkarılarak MATLAB/Simulinkprogramı ile sayısal çözümleri elde edilmiştir. Prototip iki sistem üzerindedeneysel çalışmalar yürütülmüş ve teorik sonuçlarla karşılaştırılmıştır. Eldeedilen sonuçlardan benzetim ve deneysel çalışmaların birbiriyle uyumlu olduğugörülmüştür., Thepaper describes the suitable type of magnetic circuits used in theelectromechanical valve actuators (EVAs). Two different types of EVA modelswith the disc type of magnetic circuits were designed and the effects ofvarious design parameters such as spring constant, moving mass, supply voltage,holding force on the system were investigated. The static and dynamic equationsof the system were derived and their numerical solutions were obtained with MATLAB/Simulinkprogram. The detailed theoretical analysis and experimental tests were carriedout on the manufactured different prototypes of the EVAs. Simulation andexperimental results showed a good agreement with each other.

Autonomy of power supply used in portable devices directly depends on energy efficiency of digital logic. This means that digital systems, beside high processing power and very complex functionality, must also have very low power consumption. Power consumption depends on many factors: system architecture, technology, basic cells topology-speed, and accuracy of assigned tasks. In this paper, a review and comparison of CMOS topologies techniques and operating modes is given, as CMOS technology is expected to be the optimum choice in the near future. It is shown that there is a full analogy in the behavior of digital circuits in sub-threshold and strong inversion. Therefore, synthesis of digital circuits is the same for both strong and weak operating modes. Analysis of the influence of the technology, MOS transistor threshold voltage (Vt) and power supply voltage (Vdd) on digital circuit power consumption and speed for both operating modes is given. It is shown that optimal power consumption (minimum power consumption for given speed) depends on optimal choice of threshold, and power supply voltage. Multi Vdd /Vt techniques are analyzed as well. A review and analysis of alternative logical circuit's topologies – pass logic (PL), complementary pass logic (CPL), push-pull pass logic (PPL) and adiabatic logic – is also given. As shown, adiabatic logic is the optimum choice regarding energy efficiency.

The engine mount systems have a significant effect with respect to reducing the vehicle development time and cost regarding NVH characteristics and shortcomings not solved yet. There is still a need to enhance the performance of engine mount systems for vehicle ride comfort. This research presents a simulation-based approach to design optimised engine mount components to isolate the road- and engine-induced vibrations without the need for physical prototypes. Experimental tests are performed to define hyperelastic and viscoelastic models for non-linear finite element simulations of rubber components. After the correlation between the results of simulations and the product tests, a virtual engine mount model is presented to design optimum engine mount systems with the desired static and dynamic characteristics. The stiffness curves of different shapes of designs are investigated, and the best curve is chosen as an optimum design solution using the design of experiments approach.

Mixed traffic flow with high composition of motorcycles is a common situation in many urban areas in South Asian countries like India. It consists of vehicles having diverse static and dynamic characteristics. This type of traffic is characterized by lack of queue and lane disciplines. Motorcycles, due to their smaller size, have greater freedom to manoeuver in a mixed traffic stream. They tend to accumulate near the stop line by weaving through gaps between other vehicles during the red phase. The provision of Exclusive Stopping Space for Motorcycles (ESSM) near the stop line is believed to be beneficial in discharging the motorcycles faster, thereby enhancing the efficiency of the intersection. A microscopic traffic simulation model for a signalized intersection developed specifically for mixed traffic was used in this study. The model was calibrated and tested wit h dat a from Chennai city, India. This model was used to simulate traffic flow at an intersection assuming the presence of ESSM. The efficacy of ESSM was evaluated by varying the vehicular composition, traffic volume and ESSM lengths. The findings show that for certain composition, volume levels and lengths of ESSM, delays to vehicles decrease, thereby indicating its benefits. � 2015 European Transport\Trasporti Europei.