In this work, an estimation of the key rate of measurement-device-independent quantum key distribution (MDI-QKD) protocol in free space was performed. The examined free space links included satellite-earth downlink, uplink and intersatellite link. Various attenuation effects were considered such as diffraction, atmosphere, turbulence and the efficiency of the detection system. Two cases were tested: asymptotic case with infinite number of decoy states and one-decoy state case. The estimated key rate showed the possibility of applying MDI-QKD in earth-satellite and intersatellite links, offering longer single link distance to be covered.
The main idea of castellated steel beams is to reduce their weight by creating void space (web holes) in the main beam body. This structure tends to exhibit superior properties such as advanced strength, lightweight, and cost-saving compared to the amount of steel used compared with reference beam without web holes. This study is devoted to investigating the structural behavior of double-channel cast steel beams. In this project, two pieces of a rolled hot steel channel were connected to form a new section used in the testing program. Five beams of different sections were manufactured and tested using the same length and all testing parameters conditions with only a difference in the number of openings and distance (e) between each hole to study the behavior of section to different bearing loads and deformation. Two loading points were placed on a third of the length of the castellated steel beam. This study showed that when the web holes are few, the total bearing strength decreases. As the number of web holes increased to a specific limit, the bearing strength continued to rise, and if openings exceeded a specific limit, the bearing force decreased. The rate of increase to the bearing force was found between 17.7-40.0%. Lastly, as per beam deformation, the deformation value decreased as the number of openings increased, which was taken at the maximum load of the reference beam.
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