• Journal of Navigation and Port Research
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• v.48 no.5
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• pp.418-423
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• 2024

Time delay in the remote control of maritime autonomous surface ships (RC-MASS) is a critical factor and a significant area of research. However, current studies are fragmented and lack a cohesive understanding of these delays. This study aims to review and analyze relevant literature on time delays, including policy documents, technical reports, and research papers, to provide valuable insights into RC-MASS operations. Through a systematic search, sources from the past 25 years were examined, and time delay data were extracted and categorized for statistical analysis. The findings indicate an average delay of 56.17 seconds across all categories, with considerable variability. Delays associated with navigation equipment, ship maneuvering, and ship control are prevalent across all vessels, exhibiting large values and wide variability. Although communication delays had a smaller average, they warrant further investigation due to their critical role in RC-MASS operations. This research sheds light on time delay patterns in RC-MASS, helping to identify key areas for improvement and supporting future technological advancements.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.4
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• pp.444-453
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• 2014

A throttleable rocket engine enables operational possibilities such as the docking of spacecraft, maneuvering in a certain orbit and landing on a planet's surface, altitude control, and entrance to atmosphere-less planets. Thus, throttling methods have long been researched. However, dual-manifold injectors, which represent one throttling method, have been investigated less than others. In this study, dual-manifold and single-manifold injectors were compared to determine the characteristics of dual-manifold injectors. Also, the effects of gas injection were investigated with various F/O ratios. To investigate the characteristics, mass flow rate, spray pattern, spray angle, and droplet size were measured. The spray angle and droplet size were captured by indirect photography. About 30 images were taken to assess the spray patterns and spray angle. Also, 700 images were analyzed to understand the droplet distribution and targeting area, moving to the right from the centerline with 1.11-cm intervals. The droplet size was obtained from an image processing procedure. From the results, the spray angle showed two transition regions, due to swirl momentum in the swirl chamber regardless of the F/O ratio. The droplet size showed similar trends in both dual-manifold and single-manifold injectors except in the low mass flow rate region. In the case of the dual- manifold injector, the spray cone was not fully developed in the low mass flow rate region due to low angular momentum in the swirl chamber.