Topic Review
Shipping Decarbonization
Decarbonization in the shipping industry could be achieved through technical and operational strategies such as Energy Saving Devices (ESDs) to reduce the fuel consumption of new and existing ships. According to the makers, ESDs can optimize fuel efficiency by up to 15%. Researchers review the current literature on stern hydrodynamic ESDs, which are mainly used on typical merchant vessels, i.e., bulkers, tankers, and carriers. 
  • 110
  • 05 May 2022
Topic Review
Ammonia in Various Technologies
Ammonia is a carbon-free fuel with promising applications as either a direct or indirect hydrogen carrier. Ammonia can play an important role in the decarbonization of the shipping industry, at least for deep sea routes. The key barriers to using green ammonia as an alternative fuel in maritime industry. are: (1) High production costs, due to the high capital costs associated with ammonia’s supply chain; (2) availability, specifically the limited geographical locations available for ammonia bunkering; (3) the challenge of ramping up current ammonia production; and (4) the development of ammonia-specific regulations addressing issues such as toxicity, safety, and storage. These issues are further discussed in this topic review.
  • 105
  • 11 Mar 2022
Topic Review
Design Considerations of Fixed and Floating Offshore Structures
Offshore structures exist in a variety of forms, and they are used for a variety of functions in varied sea depths. These structures are tailored for certain environments and sea depths and other design considerations. 
  • 93
  • 29 Jul 2022
Topic Review
Blade for Offshore Floating Wind Turbine Model
The Froude-scaled offshore floating wind turbine model is inevitably affected by the Reynolds number effect, making the model unable to correctly reproduce the thrust performance of the reference wind turbine (RWT). To solve this problem, an Xfoil-AirfoilPrep-Matlab (XAM) system and a wide tip speed ratio search method (WTSM) are proposed to design a wide tip speed ratio (TSR) thrust-match model blade. The XAM system is utilized to select the best airfoil for WTSM by calculating the lift and drag coefficients of several airfoils. The WTSM is utilized to optimize the blade chord and twist. It formalizes the blade chord and twist by polynomials and then optimizes the polynomial coefficients. The thrust coefficients construct the optimization object at different TSRs. For validating the effect of the redesigned blade, the thrust performance is compared to that of the RWT blade. In addition, the thrust performance of redesigned blade at different pitch angles is also calculated and compared to those of the RWT blade. Results show that the thrust performance of redesigned blade matches well with that of the RWT blade at 0 pitch angle, and it can also match the variations of that of the RWT blade at the other pitch angles well.
  • 84
  • 08 Feb 2022
Topic Review
Ocean Wave Power Generation Systems
According to the theory of mechanical vibration, only when the wave power generation system resonates with the ocean wave can the energy of the ocean wave be converted into electric energy to the greatest extent. Several topics are discussed: the current situation of ocean wave power generation system tests in real ocean waves; the optimization design of linear generator for converting ocean wave energy into electrical energy; some optimization control methods to improve the operational efficiency of ocean wave power generation systems; and the current policy and financial support of ocean wave power generation in some countries. 
  • 81
  • 04 Jan 2022
Topic Review
Wave Energy Marine Buoys
The power supply is usually the bottleneck for marine distributed systems such as buoys. Wave energy technologies are especially useful in this sense, as they can capture and convert the promising “native” renewable energy in the ocean (i.e., wave energy) into electricity.
  • 77
  • 08 Jul 2022
Topic Review
Computational Simulation Methods in Ship Broken Ice
The majority of sea ice in polar regions can be generalized into two types, (a) level ice that exists as a continuous form, and (b) broken ice that consists of discontinuous ice blocks. Broken ice includes brash ice that normally accumulates in ice channels, sliding ice pieces that form from breaking continuous ice, unconsolidated ice ridges generated by compression between ice floes, and ice floe fields (the most common broken ice condition in the polar region) that appear and evolve with natural processes. In recent years, computational simulation models have increasingly been used for the evaluation of ship operability under broken ice conditions, presenting some challenging issues. A ship’s response in broken ice is divided into two categories: resistance, which relates to the overall ship performance, and local loads, which relates to structural safety. 
  • 75
  • 22 Mar 2022
Topic Review
Classification of the Fish Inspired Robots
Compared with traditional underwater vehicles, bio-inspired fish robots have the advantages of high efficiency, high maneuverability, low noise, and minor fluid disturbance. The propulsion ability of fish comes from the coordination between muscle groups, which gives its body uniform weight distribution and a more space-saving motion structure. A body that has evolved over billions of years also has an excellent hydrodynamic shape and a reasonable structural elastic modulus. At the same time, the organic combination of movement between muscle groups is also the reason to improve the overall efficiency of movement. Finally, fish have unique fluid sensing systems. A body and (or) caudal fin (BCF) swimmer bends its body into a backward propulsive wave that extends up to its caudal fin, while median and paired fin (MPF) swimmers use the median and paired fins to gain thrust. Similar to the classification of the biological systems, fish-inspired robots can also be divided into BCF-based and MPF-based robotic fish with a series of subcategories.
  • 61
  • 10 Jun 2022
Topic Review
Performance of Unmanned Vehicles for Offshore Wind Turbines
Operations and maintenance of Offshore Wind Turbines (OWTs) are challenging, with manual operators constantly exposed to hazardous environments. Due to the high task complexity associated with the OWT, the transition to unmanned solutions remains stagnant. Efforts toward unmanned operations have been observed using Unmanned Aerial Vehicles (UAVs) and Unmanned Underwater Vehicles (UUVs) but are limited mostly to visual inspections only. Collaboration strategies between unmanned vehicles have introduced several opportunities that would enable unmanned operations for the OWT maintenance and repair activities. 
  • 57
  • 01 Jul 2022
Topic Review
Marine Exhaust Gas Treatment Systems
Two basic types of treatment systems of exhaust gases generated from marine compression ignition engines and from marine combustion systems, e.g., exhaust gas boilers, exist. These two basic exhaust gas treatment systems are used for SOx and particulate matter (PM) mitigation. Marine aqueous exhaust gas treatment and mainly SOx reduction systems have been commercially dominant. Since 2011, dry exhaust gas treatment and SOx mitigation systems have been commercially available from only one manufacturer. As can be realized, the main objective of both aqueous and dry exhaust gas treatment systems is the sorption and the rejection of SOx emissions from exhaust gases generated from marine combustion systems. One additional virtue of these systems is the sorption of particulate emissions of marine-generated exhaust gases, thus reducing the heavy metals, the soot, the polyaromatic hydrocarbons (PAH) and the sulfur contained in the particulate matter.
  • 50
  • 02 Jun 2022
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