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Topic review
Updated time: 29 Mar 2021
Submitted by: Kenji Furuichi
Definition: Cellulose triacetate (CTA)-based hollow fiber (HF) membrane is one of the commercially successful semipermeable membranes that has had a long progress since the time the excellent semi-permeable feature of cellulose-based polymers was found in 1957. Because of the reliable and excellent performances, especially for drinking water production from seawater, CTA-HFs have been widely used as reverse osmosis (RO) membranes, especially in arid regions.
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Topic review
Updated time: 25 May 2021
Submitted by: Changhee Lee
Definition: The interest in natural gas engines as an alternative to diesel engines has intensified as crude oil prices have risen and global environmental regulations have become more stringent. Natural gas engines can improve thermal efficiency through lean combustion, owing to combustion of a wide range of fuels; meanwhile, the low carbon content of the fuel reduces CO2 emissions, which is crucial in reducing greenhouse gas emissions. Natural gas engines also exhibit excellent fuel economy and low fuel costs. Unlike crude oil, natural gas is widely distributed worldwide and offers an advantage in terms of supply and demand. As a result, the demand for gas engines is increasing rapidly. Therefore, many marine engine manufacturers have developed micropilot-type gas engines that inject diesel fuel only for ignition.
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Topic review
Updated time: 19 Mar 2021
Definition: The reconfigurable vectorial thruster (RVT) is a propulsion element that changes not only the intensity of the thrust vector but also its direction. This vector reorientation by a servomotor, for example, is usually faster than the intensity change. Thus, the possibility of fast vehicle reconfiguration allows the optimized choice of the reconfigured propulsion architecture according to different tasks, minimizing the trajectory tracking error and energy consumption. Moreover, the use of RVTs can significantly reduce the total number of needed thrusters in a vehicle.
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Topic review
Updated time: 23 Mar 2021
Definition: The offshore wind is the sector of marine renewable energy with the highest commercial development at present. The margin to optimise offshore wind foundations is considerable, thus attracting both the scientific and the industrial community. Due to the complexity of the marine environment, the foundation of an offshore wind turbine represents a considerable portion of the overall investment. An important part of the foundation’s costs relates to the scour protections, which prevent scour effects that can lead the structure to reach the ultimate and service limit states. Presently, the advances in scour protections design and its optimisation for marine envi-ronments face many challenges, and the latest findings are often bounded by stakeholder’s strict confidential policies.
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