LEE- Kontrol ve Otomasyon Mühendisliği Lisansüstü Programı

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http://hdl.handle.net/11527/19359

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Yazar "Can, Hazel" ile LEE- Kontrol ve Otomasyon Mühendisliği Lisansüstü Programı'a göz atma
  • Öge
    Determination of system architectures based on RAMS analysis
    (Graduate School, 2024-06-10) Can, Hazel ; Söylemez, Mehmet Turan ; 504201116 ; Control and Automation Engineering
    Rail systems engineering is seen as a crucial transportation alternative in today's world, especially for developed and developing countries. The construction of high-speed trains and the development of these systems have therefore become a focal point for many nations around the world. One of the fundamental reasons for this focus is the ability to achieve safe, uninterrupted transportation at minimal cost within a short time frame. On the other hand, with advancing technology, air and automotive transportation have become top preferences for individuals and logistics companies. This has also necessitated the advancement and acceleration of rail systems technologies. These advancements are aimed at elevating usability and safety to the highest levels. Steps towards reliability, usability, maintainability, and safety are crucial for the development of rail transportation and its increasing prominence in the sector. However, achieving these concepts can lead to significant costs. Therefore, there has arisen a necessity to integrate cost optimization with the conducted studies. Reliability studies should be carried out with a specific engineering perspective to prevent unexpected errors and outcomes before, during, and after system operations. The reliability of a system is made possible by detailed probabilistic calculations related to the system. Therefore, system reliability is a measure of the probabilistic calculations of the system. With the increasing needs and developing systems of railway transportation, the creation of safe and uninterrupted transportation traffic has become even more important. For this reason, focusing on RAMS (Reliability, Availability, Maintainability, and Safety) analysis by rail systems engineers can provide solutions to many focal points, thereby shedding light on the answers provided by probabilistic calculations. Answers to questions such as the criticality of errors, when they will occur, and how frequently they will occur can only be obtained through probabilistic calculations. The predictions made from these calculations guide the measures to be taken and the system engineering perspective. RAMS is an important engineering principle that examines and guides these probabilistic answers from many perspectives. Many studies have been conducted to minimize errors and enhance safety in railway systems. However, as railway transportation is also widely used for passenger transport, research has generally focused on specific areas. Studies have been conducted with a holistic approach to prevent any fault that could lead to accidents, aiming to minimize harm to society and the environment. However, there is a lack of studies that directly target usability and determine the cost requirements related to system architecture from a RAMS perspective. This study is prepared as a report to guide future studies with an engineering perspective that aims for uninterrupted transportation and calculations on how to achieve high usability rates. In this research, RAMS and rail systems infrastructure concepts are primarily focused on, providing a summarized literature review related to these concepts, and methods to optimally increase availability at minimal cost are discussed. Redundant system architectures among these methods are examined in detail and evaluated from multiple perspectives with a holistic approach. An infrastructure has also been created for various modeling analyses such as the Reliability Block Diagram and Fault Tree Analysis related to these architectures. As a result, sample studies on potential interruption costs of these redundant system architectures have been conducted and compared with suitable architectures. The architectures aimed at uninterrupted transportation are implemented according to the BS IEC 61508 safety standard. While this study aims to increase availability from a RAMS perspective while ensuring uninterrupted transportation, it also allows for cost analysis of various redundant architectures. This research will focus on reliability (safety) as it will focus only on processes over hazard failure rates. It is important to emphasize that this study will focus on minimizing errors that can cause significant harm to the system, humans, and the environment, considering that even non-hazardous error rates can have the potential to stop the system. This perspective has been used since the analyses on redundant systems will be conducted for rail system transportation. In railway systems, the most important criteria are always focused on preventing errors that can cause significant harm to humans, the environment, or the system itself. One of the primary objectives of this research is to provide a general perspective on system requirements and cost analyses along with appropriate architectural selection. Therefore, necessary calculations will be made to minimize downtime costs by reducing the downtime of a system (increasing its operational time). Subsequently, calculations related to the operational cost and initial investment cost of the system will be carried out along with assumptions. One of the critical focus points of this thesis is to analyze the initial investment cost while minimizing error frequency and downtime costs. The most suitable architectural selection can only be possible by taking all cost analyses into account. Therefore, analyses have been conducted not only on how much the system downtime is reduced but also on whether the initial investment cost is suitable for all these system architecture developments. The selection of the final and most optimal architecture can vary for each system and each project. Architectures where less critical systems or components are backed up at a lower cost might be the ideal choice for the operation of that system. However, for systems where errors can lead to significant failures and consequences, architectural selections with higher initial investment costs might be appropriate. This research provides examples and studies on the redundancy of the signaling system, which is extremely critical and important for rail systems. Therefore, analyses and comments will be made considering the criticality of this redundant system in the architectural selection. This study aims to be adaptable to necessary systems or components and enable the most suitable selection among architectures due to cost constraints. Therefore, it is supportive and contributive to the literature. This research is intended as a guide aiming for uninterrupted transportation with balanced financial conditions throughout all operational periods from the design and development stages of a rail system project. Future studies will aim to provide a more comprehensive and integrated response with a safety perspective approach to analyses on high usability and financial balance.