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Öğe Modeling and Analysis of Battery Thermal Control in a Geostationary Satellite(2022) Bulut, Murat; Sözbir, NedimBattery technology has been used for geostationary satellites since the first satellite sputnik-1 was launched in 1957. The majority of larger geostationary satellite’s lives range from 7 to 15 years. During the lifetime of satellites, the batteries used must complete 1000 to 33000 cycles without any problems or likelihood of maintenance. There are three battery technologies, Li-ion, Ni-H2 and Ni-Cd, that are well proven for Geostationary satellite applications. Energy density, lifetime, weight, ampere-hour capacity, depth of discharge, ruggedness and recharge-ability, battery management, thermal management, and self-discharge are main parameters that should be considered when comparing electrical and thermal performance of these three battery technologies. The purpose of this study is to compare the thermal control system for these three batteries for three-axis stabilized geostationary satellites. In particular, the thermal dissipation was compared, which is the temperature range required for battery operation. Thermal analysis was performed for Li-ion batteries using ThermXL software, and showed a temperature results variation ranging between 10.9 oC and 32.7 oC. The temperature during the battery module was not greater that its qualification temperature results.Öğe Non-Terrestrial Network Concepts in 5G and Beyond Communication Technologies(Duzce University, 2024) Demircioglu, Erdem; Ertok, Hasan Hüseyin; Çankaya, İlyas; Sözbir, NedimMobile communication systems used in 5G and beyond will provide high-capacity, reliable and low-latency services within wide coverage areas. Currently, terrestrial networks are widely used, but it is expected that these networks will be replaced by hybrid network solutions where terrestrial and non-terrestrial networks operate together. These hybrid ones can perform cutting-edge complimentary solutions when the traditional networks have weak signal levels and geographical difficulties. The main motivation of this study can be stated as the increasing use of hybrid network structures for the solution of digital divine and access problems. In this study, design optimizations of hybrid wireless networks according to different system architectures and performance analyzes are given and various non-terrestrial network technologies are compared.Öğe A novel approach to estimating dimensions of three-axis stabilized communication satellites with optimal heat transfer(Springer, 2023) Bulut, Murat; Sözbir, NedimOne of the most challenging tasks at the early stage of satellite programs is fitting various stowed satellite configurations within different launcher envelopes to dissipate heat from the satellite. To overcome this thermal challenge, this paper proposes a practical launcher thermal analysis tool (PLTAT). The aim of this tool is to predict satellite dimension and the launcher type based on the heat dissipation requirement. The study focused on three-axis stabilized geostationary communications satellites, and north and south panels were used for heat dissipation by radiation. The remaining panels of the satellite were covered by a multilayer insulation. In the calculations, the solar arrays were placed at the north and south panels while antennas were placed at the east and west panels. The values obtained by the Excel-based VBA were compared with flying GEO satellites. Heat dissipation values calculated using PLTAT were compared with existing radiative area results. The minimum difference between the existing values and the PLTAT calculated values was 0.63%, whereas the maximum difference was 12.04%. The results from calculated PLTAT radiative areas were in agreement with existing radiative areas. Thus, PLTAT can be an alternative and useful approach when designing three-axis stabilized geostationary communications satellites.Öğe Space Activities and the Simultaneous Development of the Economy in Türkiye(Duzce University, 2024) Sözbir, Nedim; Bulut, Murat; Gülgönül, Şenol; Kuzu, Lokman; Dur, OsmanAs space technologies have become an integral part of our daily lives, they have profoundly influenced the course of human civilization since 1957. These technologies have provided humanity with many remarkable insights. Therefore, they have an important role in modern society. Satellite technology is not only vital for military and defence but also for civil applications such as transportation, communication, disaster management, agriculture planning, land, and urban planning. These applications make the space sector an engine of economic growth having advanced and the state-of-the art technology. Technological advances in space continuously benefit the citizens of developed countries. The space economy is defined as all the actions and resources that produce value and benefit to people through exploration, research, knowledge, management, and utility of space. Through satellite communications, navigation systems, earth observation missions, space science and technology research, employment is created, economic growth is achieved, and many industries become more competitive in worldwide economic market. Spinoff companies are born from space activities. In 1994, the Türkiye had its first communication satellite TURKSAT 1B built by Aerospatiale; thus, Türkiye entered the space field being an operator in its region. After millennium, the Turkish space industry has ramped-up by developing its dedicated communication and observation satellites, and their subsystems and creating a launcher system for microsatellites. Türkiye is now developing space technology more comprehensively. This article describes recent developments of space activities and future work in Türkiye. In the article, the strategies in other countries in space technologies are also discussed and suggestions are made for space technology education, development of space economy and regulation of space activities for Türkiye.Öğe Starter Selection for Diesel Engines(Düzce Üniversitesi, 2023) Gülgönül, Şenol; Sözbir, Nedim; Dur, OsmanStarter selection is a critical decision in diesel engine design. The starter performance curves are generally accepted in the industry, with current on the horizontal axis and power, volts, speed and starter torque on the vertical axis. In this way, it is not possible to compare the starter performance curves with the engine friction force curve. In this study, a method has been developed for the selection of suitable starter for diesel engines. With the developed method, the starter performance curve is converted and the engine friction curve is shown on the same graph. With this method, it can be easily understood whether the starter is suitable for a diesel engine. In addition, possible problems that may be encountered during cold start-up can be foreseen. The developed method uses actual performance measurements given by the starter manufacturer. On the engine side, if there is an existing engine, engine friction test results are used. If the engine is in the design phase, the friction force results obtained by simulation are used.Öğe The Emittance and Absorptance of External Surfaces Values Effect for Payload Panels on Geostationary Orbit Satellite: Thermal Analysis Studies(Ataturk University, 2024) Bulut, Murat; Sözbir, NedimOne of the most important parameters in the dimensioning stages of communication satellites is the calculation of the areas where the heat to be released into space is located. The satellite thermal control system calculates these areas. Thermal analyses are performed for the north and south panels where the payload equipment is located in three-axis geostationary satellites. It is important to calculate these areas where the heat to be released into space is located correctly. In this study, thermal analysis calculations were performed for a three-axis geostationary satellite with an area of 1 to 10 m2. In the calculations, the absorptance of external surfaces at the end of the satellite's life was calculated by considering 0.27. The radiator area temperature was taken as 30 oC in the calculations.Öğe Türksat 3A Uydu Proje Kapsamında Türksat Teknoloji Transfer Programı(Düzce Üniversitesi, 2023) Bulut, Murat; Sözbir, NedimTürkiye uydu işletmeci olma kararını 1989 yılında ilk defa haberleşme uydu satın almak için ihaleye çıkarak yapmıştır. 1994 yılında Türksat 1A uydusunun fırlatılmasından 2006 yılında Türksat 3A uydu üretimine kadar uydular satın alınmakla birlikte teknoloji transferi yapılmamıştır. Türksat 3A proje kapsamında ilk defa uydu teknoloji transferi programı TÜRKSAT ile Alcatel Alenia Space arasında anlaşma yapılarak başlamıştır. Türksat Teknoloji Transfer Programı (TTTP) çerçevesinde Fransa üretilen Türksat3A uydu üretim projesine 16 mühendis katılım sağlamıştır. TÜRKSAT 3A projesi kapsamında yerli haberleşme uydusu tasarım projesi olan TUSAT'a başlandı. TUSAT haberleşme uydusu tasarımı (Ön Tasarım İncelemesi (PDR düzeyi)) 2012 yılında tamamlanmıştır. Bu çalışmada, TTTP’da yapılan çalışmalar ve bu çalışmalar sonrası ülkemizde hali hazırda uydu teknolojileri konusundaki katkıları hakkında bilgiler verilecektir.
