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ÖgeLanding dampers for aircraft carrier decks(Graduate School, 2024-07-09)Shock absorbers are integral components in mitigating landing events, especially within the context of aircraft carrier landing gear design, where the formidable impact forces of horizontal or vertical landings are prevalent. Typically crafted from elastomeric materials such as pads or cables, these shock absorbers are meticulously engineered to absorb and dissipate energy upon the abrupt contact of an aircraft with the carrier deck, thus effectively reducing the force of impact. The primary objective of this study is to undertake a comprehensive analysis and evaluation of the performance exhibited by landing dampers employed during landing operations on aircraft carrier decks. This endeavour involves a multifaceted approach that encompasses various methodologies including data analysis, numerical modelling, simulations, and real-world testing. Through this concerted effort, the efficacy of these dampers is being rigorously assessed to provide a holistic understanding of their functionality. Moreover, this study endeavours to embark on the development of shock absorber designs tailored specifically for ship decks, based on the insights garnered from the aforementioned analyses. These designs are then subjected to dynamic analysis to ascertain their structural integrity and operational efficiency under realistic conditions. By leveraging advanced analytical techniques, this phase aims to optimize shock absorber designs, thereby enhancing their performance and reliability during landing operations on aircraft carrier decks. Furthermore, a comparative analysis is being conducted to juxtapose the functionality of shock-absorbing deck designs against their non-shock-absorbing counterparts. This comparative study seeks to elucidate the distinct advantages and efficacy offered by the integration of landing dampers into aircraft carrier deck configurations. By highlighting the inherent benefits of shock-absorbing deck designs, this analysis underscores their pivotal role in bolstering the safety and operational efficiency of aircraft carrier landings. In conclusion, the findings of this study are poised to make significant contributions to the field of maritime engineering by enhancing our understanding of landing dampers and their impact mitigation capabilities. By optimizing shock absorber designs and elucidating their advantages, this research endeavour not only augments the safety and operational efficiency of aircraft carrier landings but also furnishes invaluable insights for the optimization of shock absorber designs in diverse maritime environments.
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ÖgeComprehensive assessment of rov systems: An effective approach to analysis of ROV system mobilization risks(Graduate School, 2023-06-12)Remote Operating Vehicles (ROVs) are sophisticated underwater robots that play a vital role in various industries such as deep-sea exploration, oil and gas operations, underwater construction, and scientific research. These ROV systems consist of several components, including the ROV itself, Launch and Recovery Systems (LARS), umbilical cables, tethers, and power generators. Due to their complexity, it is crucial to conduct a thorough risk analysis to identify and mitigate potential hazards associated with ROV operations. This study specifically focuses on the mobilization phase of ROV systems, which involves preparing and deploying the underwater robots. During mobilization, numerous risks can arise, including mechanical or technical failures during transportation, damage to the ROV or its components during handling, and delays or disruptions caused by adverse weather conditions or logistical issues. Safeguarding against these risks is paramount to ensure the safe and successful operation of ROVs. To assess the risks involved in the mobilization process, two hybrid approaches are employed in this study. Both methods utilize the Ordered Weighted Geometric Average (OWGA) for weight distribution in terms of Severity, Detection, and Occurrence. In addition, Multi-Objective Optimization on the Basis of Ratio Analysis (MOORA) and Multi-Objective Optimization on the Basis of Simple Ratio Analysis (MOOSRA) are utilized in calculating the Risk Priority Number (RPN). These approaches aim to provide a comprehensive evaluation of the risks associated with ROV mobilization, taking into account various factors and expert opinions. By utilizing these hybrid methodologies, operators and stakeholders can gain a better understanding of the potential risks involved and make informed decisions to mitigate them effectively. In conclusion, the analysis of risks in ROV systems, particularly during the mobilization phase, is crucial for ensuring safe and successful operations. By employing hybrid approaches and incorporating expert opinions, this study aims to enhance risk assessment capabilities and facilitate the implementation of effective risk mitigation strategies in the field of underwater robotics.
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ÖgePotential wind farm design of the Caspian sea shores of Azerbaijan(Graduate School, 2022-06-23)Renewable energy sources include the sun, wind, water, the Earth's heat, and plants, all of which are perpetually renewed by nature. Renewable energy technologies convert these fuels into useable energy, such as electricity, heat, chemicals, or mechanical energy. Fossil fuels are now utilized to heat and power houses, as well as to fuel automobiles. Coal, oil, and natural gas are convenient for providing our energy demands, but there is a finite quantity of these fuels on the planet. We're consuming them at a far faster rate than they're being generated. They'll eventually run out. And, due to safety concerns and waste disposal issues, the US will phase down much of its nuclear power capacity by 2020. Meanwhile, the country's energy demands are predicted to increase by 33% during the next 20 years. Renewable energy may be able to fill the void. Renewable energy is better for the environment even if we had a limitless supply of fossil resources. Renewable energy systems are frequently referred to as "clean" or "green" since they create little, if any, pollutants. Renewable energy will also assist us in achieving energy security and independence. Replacing part of our petroleum with plant-based fuels, for example, may save money while also increasing our energy security. Renewable energy is abundant, and technology is always improving. Renewable energy may be used in a variety of ways. In our daily lives, the majority of us currently utilize renewable energy. The design of the wind farm has been researched in the fourth chapter. This section focuses on selecting the best site for the wind farm. The situation of the wind blowing around the Absheron area is described in general. The absheron region appears to be typically adequate in terms of wind speed when we look at the wind maps during the studies. In terms of depth, it appears that the region's depth ranges between 20 and 40 meters. On the other hand, the presence of onshore wind farms in the northern half of the Absheron peninsula makes this region more grid-connected. In terms of wind speed, the location in the southern portion of the Absheron peninsula where the wind speed of 7.69 m/sec was found to be the most favorable (A region). However, as previously noted, the sea section in the northern half of the Absheron peninsula is the best location for grid connection. Part B, in one of the zones with the highest wind speed closest to the land, has been judged to be the most suited location. The greatest water depth in this area is 20 meters, and the monopile foundations for the wind turbines to be erected are considered adequate. Furthermore, it has been found that ship traffic is not a barrier for this region, and as is well known, Azerbaijan has oil and natural gas deposits in the Caspian, and there is no pipeline running through this region, despite the threat of underwater pipes. The Vestas117-4.2 MW model was chosen as the wind turbine's model. Because the selected wind turbine's hub height is 91.5 meters, a reference wind speed of 50 meters (8.25 m/sec) was used, and the wind speed at 91.5 meters was found to be 8.7 m/sec. Furthermore, the annual energy production of a wind turbine was calculated based on its data to be 14.7 GWAC/year
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ÖgePotential wind farm design in Western Black Sea region of Turkey(Graduate School, 2022-01-21)Today, wind energy has become one of the common types used to meet the ever-increasing need for electrical energy. Wind energy, which has zero carbon dioxide emissions compared to other classical types of electric power generation (coal, natural gas), is becoming more and more common. Especially offshore wind turbines are calculated more efficiently compared to onshore. This is due to the high wind speed at sea and the almost absence of obstacles that the wind may encounter. Developing countries such as Turkey need to spend large sums of money to meet their electrical energy needs. And a part of the electricity (26%) produced in Turkey is obtained from hydroelectric power plants, but this is not enough to guarantee the whole of Turkey with electrical energy. Most of Turkey's electricity generation (58%) is made with coal and natural gas. Only 15% of energy comes from wind turbines, geothermal and solar panels. As can be seen from the percentages, this is a major source of problems for Turkey, both economically and environmentally. Taking these into account, for a country surrounded by sea on 3 sides, turning to offshore wind turbines will provide great advantages for Turkey, both environmentally and economically. In this thesis, a potential wind farm design has been made in the western black sea region of Turkey. The design phase was made by taking these criteria into account: Technical (Wind speed and water depth), environmental (Bird migrations, ports and ship routes, fault lines, underwater cables, civil aviation, military regions, territorial water), social (Tourisim and fishery), logistics, grid connection, type of wind turbine and choosing layout. Comprehensive analyzes were made by taking these criteria into account. In addition, in this thesis, the situation of wind energy in the world and in Turkey, Turkey's wind energy potential has been investigated. Information was also shared on how the use of classical energy types and the use of hydroelectric power plants are harmful to nature. The model of the wind turbine was decided to be the Vestas production V174-9.5 MW™ (due tp logistical availability). In addition, annual energy production was calculated both in accordance with the number of wind turbines (99) calculated in accordance with the size of the area of the selected region, and by taking into account the wind speed. The power of the offshore wind farm is calculated to be 940 MW. Considering the depth, it was decided that the foundation of the wind turbine should be monopile. Finally, the total force and maximum momentum ( and = 152,417,746 ) to be applied to the monopile were determined by using the Morrison's equation, these calculations were based on the highest wind speed data of 30 years that (1978-2009) blowing from Şile to the selected region, obtained from the General Directorate of Meteorology of the Ministry of Environment and Forestry of the Republic of Turkey. The design of the wind farm has been done successfully.
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ÖgeA generalized deep reinforcement learning based controller for heading keeping in waves(Graduate School, 2022-06-21)Reinforcement Learning (RL) is a machine learning method where a learner (the agent) tries to maximize a reward by learning how to act under different environmental circumstances. The agent looks at the state of its environment (through the state vector), takes an action, and then gets a reward and the next state of its environment. The agent improves its action-taking strategy (policy) with every action it experiments with. RL methods have been used for many decision-making problems including control problems with promising results. Unlike many traditional control methods, a model-free RL doesn't need any environment dynamics to operate. This is especially beneficial for problems where the model dynamics are non-linear or not well-known. However, classical controllers are still the most used method of control for maritime applications. Heading-keeping is a maritime control problem where a controller's objective is to keep the heading (yaw) angle of a vehicle constant. Generally speaking, the industry standard is to use traditional feedback controllers such as PID for this problem. This study focuses on designing a generalized RL controller for the heading-keeping problem in waves. The study compares the designed RL controller to a traditional controller in terms of yaw error and rudder usage and observes that the designed RL-based controller performs better than the used traditional controller. The first iterations of the RL agent had many issues. Unlike traditional controllers, the RL agents don't inherently recognize that in an idealized environment they can deal with waves coming from 0 and 180 degrees with almost zero rudder usage. On top of that, the first few developed agents had problems with excessive rudder usage, steady-state error, and overshooting behavior. All of these problems have been solved in the final iteration of the RL agent. Instead of just explaining the final agent, the thesis starts off with a weak RL agent and explains how it can be improved iteratively. This way the thesis explains how one might approach the problem of developing an RL-based controller. The first section focuses on giving a rough summary of RL and the problem case, explains the purpose of the thesis, then talks about previous work over marine movement control in literature. Some detailed information about the used tools and simulation environment is also given here. The second section introduces LQR controllers and designs an LQR controller for the heading keeping problem. The third section explains RL in-depth to lay the foundation for the upcoming sections. The fourth section starts with a naively designed simple RL agent and iteratively improves it. In each iteration of development, the agent is compared to the designed LQR controller, its weaknesses are analyzed, and the improvements for the next iteration are determined. The fifth section summarizes the previous sections, explains the contributions of the thesis, and discusses possible future work.