With growing awareness of climate change and an increased interest in renewable energy, resources like offshore wind are projected to grow in the near future. One key issue within offshore wind is how to stabilize the floating system when it experiences large wind and wave forces that impact its performance and shorten its operating life. Researchers have been exploring structural control methods and creating modeling tools to evaluate the performance of the control methods. One such tool is OpenFAST, the industry standard for modeling wind turbine dynamics, and the goal of this paper is to build upon the existing capabilities of OpenFAST. Inerter-based structural control methods offer arguably better performance than traditional vibration absorbers, and the configuration proposed in this paper also offers the ability to use a generator as an element in the structural controller. This allows extra energy to be generated along with the improvement in vibration absorption. Through this study, this inerter-based control method is explored through the lens of an established modeling tool to provide the validation for the model to explore which load cases the inerter performs best in and what design considerations must be made. In addition, the energy harvesting potential of the inerter system is evaluated and shown to increase the system's capabilities especially under stormy ocean conditions. / Master of Science / With growing awareness of climate change and an increased interest in renewable energy, resources like offshore wind are projected to grow in the near future. One key issue within offshore wind is how to stabilize the floating system when it experiences large wind and wave forces which impact its performance and shorten its lifespan. Researchers have been exploring several methods and creating modeling tools to evaluate the performance of control methods. One such tool is OpenFAST, the industry standard for modeling wind turbine dynamics, and the goal of this paper is to build upon the existing capabilities of OpenFAST. Structural control methods based on an element called an inerter offer arguably better performance than traditional vibration absorbers. The design in this paper also offers the ability to use an electrical generator as an element in the structural controller. This allows extra energy to be generated along with the reduced vibrations. Through this study, this inerter-based control method is explored through the lens of an established modeling tool to provide validation for the model. Another goal is to explore which scenarios the inerter performs best and what design considerations must be made for future development. In addition, the energy harvesting potential of the inerter system is evaluated and shown to increase the system's capabilities.

Submitted by Willian Minnemann Kuhnert null (willian.kuhnert@feb.unesp.br) on 2016-08-29T20:53:53Z No. of bitstreams: 1 VERSAO_FINAL_WILLIANMK.pdf: 7510529 bytes, checksum: d0f36cb6fb5aeb748d7d26333a6c853c (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-08-31T12:32:11Z (GMT) No. of bitstreams: 1 kuhnert_wm_me_bauru.pdf: 7510529 bytes, checksum: d0f36cb6fb5aeb748d7d26333a6c853c (MD5) / Made available in DSpace on 2016-08-31T12:32:11Z (GMT). No. of bitstreams: 1 kuhnert_wm_me_bauru.pdf: 7510529 bytes, checksum: d0f36cb6fb5aeb748d7d26333a6c853c (MD5) Previous issue date: 2016-07-19 / Fundação para o Desenvolvimento da UNESP (FUNDUNESP) / O isolamento de vibração é a técnica mais utilizada atualmente para a proteção de mecanismos e estruturas que sofrem excitação, seja ela por choque/impacto, seja ela harmônica. Este trabalho adiciona ao isolador de vibração comum, composto por molas e amortecedores, um elemento conhecido como inerter, que recentemente tem chamado bastante a atenção da comunidade científica, e também, separadamente, adiciona amortecedores não lineares, com o intuito de avaliar a influência destes elementos no isolamento. As curvas de transmissibilidade obtidas, que indicam a performance do isolamento à excitação harmônica, para os isoladores com inerter são comparadas à de um isolador comum composto somente por uma mola, e entre elas, enquanto que as curvas obtidas para os isoladores com amortecedores não lineares são comparadas entre si e à de um isolador comum com amortecimento linear. Os resultados obtidos mostram que a adição do inerter aos isoladores de vibração pode ser muito benéfica para o isolamento em determinadas faixas de frequência, mas em outras não, e tais faixas dependem de como o isolador é construído. Além disso, os isoladores com inerter são benéficos principalmente para sistemas subamortecidos. Os isoladores subamortecidos com inerter apresentaram características de isolamento diferentes uns dos outros, o que os leva a serem aplicados em diferentes situações. Os resultados obtidos para os isoladores com amortecedores não lineares mostraram que tais sistemas também podem melhorar ou piorar o isolamento em determinadas faixas de frequência quando comparados à um isolador com amortecimento linear. / The vibration isolation is currently the most used technique for protecting mechanisms and structures which are under shock/impact or harmonic excitation. This work presents to the common vibration isolator, consisted by springs and dampers, an element known as inerter, which recently has took great attention in the scientific community, and also presents the use of non-linear dampers to analyze the influence of these elements on isolation. The transmissibility curves obtained, which indicate the performance of the isolation for systems under harmonic excitation, for the isolators with the inerter element are compared with the spring-damper isolator frequency response as well the isolators with non-linear damping. The results obtained show that the addition of the inerter element can be beneficial for the isolation performance in a frequency range, but degrades the high frequency isolation, and they depend on how the isolator is built. Besides, the isolators with inerter are beneficial mainly for underdamped systems. The different underdamped systems with inerter presented unique isolation characteristics. The results obtained for the isolators with non-linear dampers presented that such systems can also improve the isolation in certain frequency ranges when compared to an isolator with linear damping. / FUNDUNESP: 110/2013-CCp/PIB

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / his paper proposes a Lean Green model for increasing profitability in small and medium-sized businesses operating within the plastics sector. This model will use the 5S methodology, KanBan for inventory control and TPM to standardize new corrective and preventive maintenance processes. As an added contribution, a Circular Economy process will be included to reuse products, thus reducing consumption and generating less solid waste. In this way, companies will not only prevent damaging the environment but will also guarantee their compliance with regulatory standards. As a result, an 11% reduction was observed in the acquisition of supplies and spare parts for machine maintenance along with a 4% reduction in the number of machine breakdowns.

Following successful implementation of inerters for passive mechanical control in racing cars, this research studies potential innovative solutions for railway vehicle suspensions by bringing the inerter concept to the design of mechatronic systems. The inerter is a kinetic energy storage device which reacts to relative accelerations; together with springs and dampers, it can implement a range of mechanical networks distinguished by their frequency characteristics. This thesis investigates advantages of inerter-based novel devices to simplify the design of active solutions. Most of the research work is devoted to the enhancement of vertical ride quality; integrated active-plus-novel-passive solutions are proposed for the secondary suspensions. These are defined by different active control strategies and passive configurations including inerters. By optimisation of the suspension parameters, a synergy between passive and active configurations is demonstrated for a range of ride quality conditions. The evidence of cooperative work is found in the reduction of the required active forces and suspension travelling. This reveals a potential for reducing the actuator size. Benefits on power requirements and actuator dynamic compensation were also identified. One of the strategies features a nonlinear control law proposed here to compensate for 'sky-hook' damping effects on suspension deflection; this, together with inerter-based devices attains up to 50% in active force reduction for a setting providing 30% of ride quality enhancement. The study is developed from both, an analytical and an engineering perspective. Validation of the results with a more sophisticated model is performed. The lateral stability problem was briefly considered towards the end of the investigation. A potential use of inerter-based devices to replace the static yaw stiffness by dynamic characteristics was identified. This leads to a synergy with 'absolute stiffness', an active stability solution for controlling the wheelset 'hunting' problem, for reducing the creep forces developed during curve negotiation.

Over the past decade, offshore wind has positioned itself as one of the most promising renewable energy markets. While this field is currently dominated by fixed-bottom wind turbines located within a limited depth range, floating turbines are showing promise as a way to capture the more developed wind profiles available in deeper waters. Currently, the main challenge with floating offshore wind is that the systems experience larger ultimate loads compared to fixed bottom turbines. These larger loads are caused by the increased motion inherent with floating structures. This study looks to analyze the effects that traditional and inerter based structural control methods can have on vibration reduction of floating offshore wind turbines. Models are developed adding tuned mass dampers (TMD) and tuned inerter dampers (TID) into the three main columns of a semisubmersible platform. Results showed that for free decay tests, heave and pitch root mean square (RMS) values were reduced significantly by the addition of passive structural control. The inerter based structural control consistently outperformed traditional TMD and also allowed for similar performance with significantly reduced physical mass values. For regular wave excitation both control methods resulted in significant reductions to the heave and pitch RMS values compared to the baseline, with the TID outperforming the TMD . And for an irregular wave analysis, it was found that both control configurations were still able to provide meaningful reductions to the baseline model. / Master of Science / Over the past decade, offshore wind has positioned itself as one of the most promising renewable energy markets. While this field is currently dominated by fixed-bottom wind turbines located within a limited depth range, floating turbines are showing promise as a way to capture the more developed wind profiles available in deeper waters. Currently, the main challenge with floating offshore wind is that the systems experience larger ultimate loads compared to fixed bottom turbines. These larger loads are caused by the increased motion inherent with floating structures. This study looks to analyze the effects that traditional and enhanced motion reduction technology can have on floating offshore wind turbines. Models are developed adding the traditional and enhanced motion reduction technology into the three main columns of a semisubmersible platform. Results showed that for several different tests, the motion reduction technology has a positive effect on the turbines. For test dropping the system from a set height, the motion reduction technology allowed the system to come to rest much faster. Moreover, the enhanced technology performed better than the traditional technology. The same results were found when the system was excited by simulated waves.