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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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23 pages, 7520 KB  
Article
Evaluation of Coastal Protection Strategies at Costa da Caparica (Portugal): Nourishments and Structural Interventions
by Francisco Sancho
J. Mar. Sci. Eng. 2023, 11(6), 1159; https://doi.org/10.3390/jmse11061159 - 31 May 2023
Cited by 12 | Viewed by 8849
Abstract
Costa da Caparica beach, in Portugal, has suffered from chronic erosion for the last 50 years, a phenomenon that has been countered by various management interventions. This study aims at comparing sixteen possible interventions, thus identifying the most effective one(s) in terms of [...] Read more.
Costa da Caparica beach, in Portugal, has suffered from chronic erosion for the last 50 years, a phenomenon that has been countered by various management interventions. This study aims at comparing sixteen possible interventions, thus identifying the most effective one(s) in terms of reducing beach erosion or even promoting beach accretion. This exercise is achieved using a one-line shoreline evolution model, calibrated with in situ field data, forced by local wave conditions. The target management period is 25 years. In the calibration phase, it is found that the annual mean alongshore net sediment transport along the 24 km sandy coast is variable in direction and magnitude, but it is mostly smaller than ±50 × 103 m3/year. This net transport results from the imbalance of northward/southward-directed bulk transports of circa tenfold-larger magnitudes. This affects the overall sediment balance at the urban beaches, as well as the effectiveness of the intervention strategies. The results show that the present management strategy is effective in holding the shoreline position, although deploying the same nourishment volume but over a shorter area could lead to better results. The best solutions, which are capable of promoting beach accretion, implicate the lengthening of the terminal groin at the northern extremity of the beach. The results from this study can support decision makers in identifying the most appropriate management action, not just locally but also at other coastal regions where similar problems persist and the same methodology could be applied. Full article
(This article belongs to the Special Issue Sediment Dynamics in Artificial Nourishments)
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18 pages, 695 KB  
Article
Wind-Assisted Ship Propulsion: Matching Flettner Rotors with Diesel Engines and Controllable Pitch Propellers
by Veronica Vigna and Massimo Figari
J. Mar. Sci. Eng. 2023, 11(5), 1072; https://doi.org/10.3390/jmse11051072 - 18 May 2023
Cited by 31 | Viewed by 7949
Abstract
The harvesting of wind energy and its transformation into a thrust force for ship propulsion are gaining in popularity due to the expected benefit in fuel consumption and emission reductions. To exploit these benefits, a proper matching between the conventional diesel engine-screw propeller [...] Read more.
The harvesting of wind energy and its transformation into a thrust force for ship propulsion are gaining in popularity due to the expected benefit in fuel consumption and emission reductions. To exploit these benefits, a proper matching between the conventional diesel engine-screw propeller propulsion plant and the wind-assisted plant is key. This paper aims to present a method and a code for the preliminary sizing of a ship propulsion plant based on a diesel engine, a controllable pitch propeller, and one or more Flettner rotors. A mathematical model describing the behaviour of the rotor in terms of propulsive thrust and power is proposed. The rotor model has been integrated into an existing diesel propulsion model in order to evaluate the ship’s fuel consumption. The ship’s propulsion model is written in a parametric form with respect to the following design parameters: ship dimensions and resistance-speed curve, propeller diameter, engine power, rotor geometry, and true wind conditions. The methodology helps in evaluating the engine–propeller working points and eventually the total ship propulsive power, including the power required to spin the rotor. It provides a way to compare wind-assisted propulsive solutions in terms of fuel consumption and CO2 emissions. A 3000-ton Ro-Ro/Pax ferry has been selected as a case study. Results on the parametric analysis of rotor dimensions and propeller pitch optimization are presented. Full article
(This article belongs to the Section Ocean Engineering)
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31 pages, 7824 KB  
Review
Digital Twin in the Maritime Domain: A Review and Emerging Trends
by Nuwan Sri Madusanka, Yijie Fan, Shaolong Yang and Xianbo Xiang
J. Mar. Sci. Eng. 2023, 11(5), 1021; https://doi.org/10.3390/jmse11051021 - 10 May 2023
Cited by 100 | Viewed by 23200
Abstract
This paper highlights the development of Digital Twin (DT) technology and its admittance to a variety of applications within the maritime domain in general and surface ships in particular. The conceptual theory behind the evolution of DT is highlighted along with the development [...] Read more.
This paper highlights the development of Digital Twin (DT) technology and its admittance to a variety of applications within the maritime domain in general and surface ships in particular. The conceptual theory behind the evolution of DT is highlighted along with the development of the technology and current progress in practical applications with an exploration of the key milestones in the extension from the electrification of the shipping sector towards the realization of a definitive DT-based system. Existing DT-based applications within the maritime sector are surveyed along with the comprehension of ongoing research work. The development strategy for a formidable DT architecture is discussed, culminating in a proposal of a four-layered DT framework. Considering the importance of DT, an extensive and methodical literature survey has also been carried out, along with a comprehensive scientometric analysis to unveil the methodical footprint of DT in the marine sector, thus leading the way for future work on the design, development and operation of surface vessels using DT applications. Full article
(This article belongs to the Special Issue Maritime Autonomous Surface Ships)
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24 pages, 3991 KB  
Article
Biodiversity of UV-Resistant Bacteria in Antarctic Aquatic Environments
by Daniela Coppola, Chiara Lauritano, Gianluca Zazo, Genoveffa Nuzzo, Angelo Fontana, Adrianna Ianora, Maria Costantini, Cinzia Verde and Daniela Giordano
J. Mar. Sci. Eng. 2023, 11(5), 968; https://doi.org/10.3390/jmse11050968 - 1 May 2023
Cited by 23 | Viewed by 7422
Abstract
Antarctica is an untapped reservoir of bacterial communities, which are able to adapt to a huge variety of strategies to cope with extreme conditions and, therefore, are capable of producing potentially valuable compounds for biotechnological applications. In this study, 31 UV-resistant bacteria collected [...] Read more.
Antarctica is an untapped reservoir of bacterial communities, which are able to adapt to a huge variety of strategies to cope with extreme conditions and, therefore, are capable of producing potentially valuable compounds for biotechnological applications. In this study, 31 UV-resistant bacteria collected from different Antarctic aquatic environments (surface sea waters/ice and shallow lake sediments) were isolated by UV-C assay and subsequently identified. A phylogenetic analysis based on 16S rRNA gene sequence similarities showed that the isolates were affiliated with Proteobacteria, Actinobacteria and Firmicutes phyla, and they were clustered into 15 bacterial genera, 5 of which were Gram negative (Brevundimonas, Qipengyuania, Sphingorhabdus, Sphingobium, and Psychrobacter) and 10 of which were Gram positive (Staphylococcus, Bacillus, Mesobacillus, Kocuria, Gordonia, Rhodococcus, Micrococcus, Arthrobacter, Agrococcus, and Salinibacterium). Strains belonging to Proteobacteria and Actinobacteria phyla were the most abundant species in all environments. The genus Psychrobacter was dominant in all collection sites, whereas bacteria belonging to Actinobacteria appeared to be the most diverse and rich in terms of species among the investigated sites. Many of these isolates (20 of 31 isolates) were pigmented. Bacterial pigments, which are generally carotenoid-type compounds, are often involved in the protection of cells against the negative effects of UV radiation. For this reason, these pigments may help bacteria to successfully tolerate Antarctic extreme conditions of low temperature and harmful levels of UV radiation. Full article
(This article belongs to the Special Issue Biodiversity, Adaptation Strategies, and Opportunities in Extreme Marine Environments)
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15 pages, 3774 KB  
Article
Three-Dimensional-Printed Coral-like Structures as a Habitat for Reef Fish
by Asa Oren, Ofer Berman, Reem Neri, Ezri Tarazi, Haim Parnas, Offri Lotan, Majeed Zoabi, Noam Josef and Nadav Shashar
J. Mar. Sci. Eng. 2023, 11(4), 882; https://doi.org/10.3390/jmse11040882 - 21 Apr 2023
Cited by 14 | Viewed by 6298
Abstract
Coral reefs are three-dimensional biogenic structures that provide habitat for plenty of marine organisms; yet, coral reefs are deteriorating worldwide. Hence, it is essential to identify suitable substitutes for such coral services. This study examines reef fishes’ behavior and reactions to three-dimensional-printed (3DP) [...] Read more.
Coral reefs are three-dimensional biogenic structures that provide habitat for plenty of marine organisms; yet, coral reefs are deteriorating worldwide. Hence, it is essential to identify suitable substitutes for such coral services. This study examines reef fishes’ behavior and reactions to three-dimensional-printed (3DP) corals based on scanned Stylophora pistillata, as well as modified 3DP models. In particular, fishes’ unresponsiveness to the color, shape, morphology, and material of 3DP models both in vitro and in situ experiments was investigated. Coral reef fishes responded to the 3DP corals and demonstrated their usage in a range of services. Moreover, a greater number of fish species interacted more with 3DP models than they did with live corals. Furthermore, specific reef fish species, such as Sea Goldies (Pseudanthias squamipinnis), showed a preference for specific 3DP coral color, and other species demonstrated preferences for specific 3DP model shapes. The current study results show that three-dimensional-printed coral models can substitute for live corals for certain types of reef fish services. Full article
(This article belongs to the Topic Marine Ecology, Environmental Stress and Management)
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29 pages, 23244 KB  
Article
Analysis of the Mooring Effects of Future Ultra-Large Container Vessels (ULCV) on Port Infrastructures
by Sara Sanz Sáenz, Gabriel Diaz-Hernandez, Lutz Schweter and Pieter Nordbeck
J. Mar. Sci. Eng. 2023, 11(4), 856; https://doi.org/10.3390/jmse11040856 - 18 Apr 2023
Cited by 22 | Viewed by 7364
Abstract
The size of container vessels is continuously growing, always exceeding expectations. Port authorities and terminals need to constantly adapt and face challenges related to maritime infrastructure, equipment, and operations, as these are the principal areas affected by the future Ultra Large Container Vessels [...] Read more.
The size of container vessels is continuously growing, always exceeding expectations. Port authorities and terminals need to constantly adapt and face challenges related to maritime infrastructure, equipment, and operations, as these are the principal areas affected by the future Ultra Large Container Vessels (ULCVs). Maneuvring areas are at their limits, and mooring equipment is at an increased risk of being overloaded. This study aims to analyze the limitations that present mooring systems may face when ULCVs are subjected to wind and passing-ship forces exerted by a future ULCV and wind forces through Dynamic Mooring Analysis (DMA). A hypothetical and massive future ULCV with a capacity of 40,000 TEU is compared to the Emma Maersk, which is a present vessel that regularly calls at container terminals. The Emma Maersk, with its current mooring arrangement, experiences higher motion than future ULCVs, which experience higher forces but are also moored with more and stronger lines. This translates into considerably higher loads in the mooring system, potentially compromising safe mooring conditions at the terminal. Mitigating measures are proposed in the study to face these limitations. In addition, the study explores the potential of new and innovative mooring technologies, such as high-strength synthetic ropes and smart mooring systems, to address the challenges posed by ULCVs. A container terminal at the Port of Rotterdam, Europe’s largest sea port, has been analyzed as a case study. The terminal is located next to a busy fairway that leads to other container terminals, justifying the need to analyze both wind and passing-ship effects on moored ships. Full article
(This article belongs to the Special Issue Advances in Ship and Marine Hydrodynamics)
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33 pages, 23865 KB  
Article
Visualization of Underwater Radiated Noise in the Near- and Far-Field of a Propeller-Hull Configuration Using CFD Simulation Results
by Julian Kimmerl and Moustafa Abdel-Maksoud
J. Mar. Sci. Eng. 2023, 11(4), 834; https://doi.org/10.3390/jmse11040834 - 15 Apr 2023
Cited by 8 | Viewed by 6064
Abstract
Underwater radiated noise is part of the anthropogenic emissions into the environment and as such a pressing problem for the preservation of the marine ecosystem. In order to direct attention to the most relevant noise sources associated with ships it is crucial to [...] Read more.
Underwater radiated noise is part of the anthropogenic emissions into the environment and as such a pressing problem for the preservation of the marine ecosystem. In order to direct attention to the most relevant noise sources associated with ships it is crucial to precisely determine the local origins of the acoustic emissions. As acoustics are by nature perceived through a very subjective auditory perception, visual post-processing support is required in engineering applications to assess the impact on structures and to create an understanding of the overall noise field geometrically, topologically, and directionally. In the context of CFD simulations, this may be achieved by considering the pressure pulses on domain boundary surfaces or passive surfaces, or by evaluating various volumetric information, such as Proudman acoustic sources or the Lighthill stress tensor, which is the fundamental input for many acoustic analogies including the Ffowcs-Williams-Hawkings method. For a propeller-hull configuration, the acoustic emissions from modeled and scale-resolved turbulence two-phase CFD analyses are evaluated in detail with different visualization methods. It is shown that the spatial distribution information of frequency domain pressure pulses, and the corresponding complex phase angles on specific passive geometries, as well as the Lighthill stress tensor may be utilized to create a better understanding of underwater acoustics. This allows the identification of source types and their respective excitation of the hull and emission characteristics of the hydrodynamic sources into the fluid domain, as well as the effect of the CFD simulation domain geometry extent. Full article
(This article belongs to the Section Ocean Engineering)
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19 pages, 15171 KB  
Article
Punctiform Breakup and Initial Oceanization in the Central Red Sea Rift
by Ya-Di Sang, Bakhit M. T. Adam, Chun-Feng Li, Liang Huang, Yong-Lin Wen, Jia-Ling Zhang and Yu-Tao Liu
J. Mar. Sci. Eng. 2023, 11(4), 808; https://doi.org/10.3390/jmse11040808 - 10 Apr 2023
Cited by 7 | Viewed by 4785
Abstract
The Central Red Sea Rift is a natural laboratory to study the transition from rifting to spreading. Based on new reflection seismic profiles and gravity modeling, we examined the crustal structure, tectonic evolution, breakup mechanism, and future evolution of the Central Red Sea [...] Read more.
The Central Red Sea Rift is a natural laboratory to study the transition from rifting to spreading. Based on new reflection seismic profiles and gravity modeling, we examined the crustal structure, tectonic evolution, breakup mechanism, and future evolution of the Central Red Sea Rift. Along this rift axis, the breakup of continental lithosphere is discontinuous and the oceanic crust is limited to the axial deeps. The punctiform breakup and formation of deeps is assisted by mantle upwelling and topographic uplift, but the nucleation is directly controlled by the normal-fault system. The discontinuities spaced between axial deeps within the relatively continuous central troughs are presently axial domes or highs and will evolve into new deeps with tectonic subsidence. Isolated deeps will grow and connect with each other to become a continuous central trough, before transitioning into a unified spreading center. Full article
(This article belongs to the Special Issue Recent Advances in Geological Oceanography II)
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19 pages, 4400 KB  
Article
Speed and Fuel Ratio Optimization for a Dual-Fuel Ship to Minimize Its Carbon Emissions and Cost
by You-Chen Shih, Yu-An Tzeng, Chih-Wen Cheng and Chien-Hua Huang
J. Mar. Sci. Eng. 2023, 11(4), 758; https://doi.org/10.3390/jmse11040758 - 31 Mar 2023
Cited by 24 | Viewed by 5846
Abstract
In this study, nondominated sorting genetic algorithm II (NSGA-II) was used to minimize the cost and carbon emissions of a liquefied natural gas (LNG) dual-fuel ship for a given route. This study considered the regulations of emission control areas (ECA) and the European [...] Read more.
In this study, nondominated sorting genetic algorithm II (NSGA-II) was used to minimize the cost and carbon emissions of a liquefied natural gas (LNG) dual-fuel ship for a given route. This study considered the regulations of emission control areas (ECA) and the European Union (EU) Emissions Trading System (ETS) to determine the optimal speed and LNG/oil ratio for the ship. NSGA-II used the arrival time at each port and the LNG usage ratio for each voyage leg as its genes. The time window for arrival, the fuel cost, and potential EU carbon emission regulations were used to estimate the cost of the considered voyage. Moreover, fuel consumption was determined using historical data that were divided by period, machinery, and voyage leg. The results indicated that the optimal speed and fuel ratio could be determined under any given fuel and carbon price profile by using NSGA-II. Finally, the effects of regulations and carbon price differences on the optimal speed and fuel ratio were investigated. The cost minimization solution was susceptible to being affected by the regulations of ECAs and the EU ETS. The speed profile of the cost minimization solution was found to have a tendency to travel at faster-than-average speeds outside ECAs and non-EU regions, and travel slower in ECAs and EU regions. Meanwhile, the selection of fuel type showed that 100% traditional fuel oil in all regions, but with sufficiently high EU carbon permit cost, tends to use 100% LNG in EU regions. Full article
(This article belongs to the Special Issue Energy Efficiency in Marine Vehicles)
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9 pages, 2105 KB  
Article
Underwater Positioning System Based on Drifting Buoys and Acoustic Modems
by Pablo Otero, Álvaro Hernández-Romero, Miguel-Ángel Luque-Nieto and Alfonso Ariza
J. Mar. Sci. Eng. 2023, 11(4), 682; https://doi.org/10.3390/jmse11040682 - 23 Mar 2023
Cited by 17 | Viewed by 4999
Abstract
GNSS (Global Navigation Satellite System) positioning is not available underwater due to the very short range of electromagnetic waves in the sea water medium. In this article a LBL (Long Base Line) acoustic repeater system of the GNSS positioning is presented. The system [...] Read more.
GNSS (Global Navigation Satellite System) positioning is not available underwater due to the very short range of electromagnetic waves in the sea water medium. In this article a LBL (Long Base Line) acoustic repeater system of the GNSS positioning is presented. The system is hyperbolic, i.e., based on time differences and it does not need very accurate atomic clocks to synchronize repeaters. The system architecture and system calculations that demonstrate the feasibility of the solution are presented. The system uses four buoys that sequentially transmit their position and the time of the instant of transmission, for which they are equipped with GNSS receivers and acoustic modems. The buoys can be fixed or even drifting, but they are inexpensive devices, which pose no hazard to navigation and can be easily and quickly deployed for a specific underwater mission. The multilateration algorithm used in the receiver is presented. To simplify the algorithm, the depth of the receiver, measured by a depth sensor, is used. Results are presented for the position error of an underwater vehicle due to its displacement during the transmission frame of the four buoys. Full article
(This article belongs to the Special Issue Navigation and Localization for Autonomous Marine Vehicles)
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21 pages, 5074 KB  
Article
Underwater Target Detection Based on Improved YOLOv7
by Kaiyue Liu, Qi Sun, Daming Sun, Lin Peng, Mengduo Yang and Nizhuan Wang
J. Mar. Sci. Eng. 2023, 11(3), 677; https://doi.org/10.3390/jmse11030677 - 22 Mar 2023
Cited by 131 | Viewed by 12715
Abstract
Underwater target detection is a crucial aspect of ocean exploration. However, conventional underwater target detection methods face several challenges such as inaccurate feature extraction, slow detection speed, and lack of robustness in complex underwater environments. To address these limitations, this study proposes an [...] Read more.
Underwater target detection is a crucial aspect of ocean exploration. However, conventional underwater target detection methods face several challenges such as inaccurate feature extraction, slow detection speed, and lack of robustness in complex underwater environments. To address these limitations, this study proposes an improved YOLOv7 network (YOLOv7-AC) for underwater target detection. The proposed network utilizes an ACmixBlock module to replace the 3 × 3 convolution block in the E-ELAN structure, and incorporates jump connections and 1 × 1 convolution architecture between ACmixBlock modules to improve feature extraction and network reasoning speed. Additionally, a ResNet-ACmix module is designed to avoid feature information loss and reduce computation, while a Global Attention Mechanism (GAM) is inserted in the backbone and head parts of the model to improve feature extraction. Furthermore, the K-means++ algorithm is used instead of K-means to obtain anchor boxes and enhance model accuracy. Experimental results show that the improved YOLOv7 network outperforms the original YOLOv7 model and other popular underwater target detection methods. The proposed network achieved a mean average precision (mAP) value of 89.6% and 97.4% on the URPC dataset and Brackish dataset, respectively, and demonstrated a higher frame per second (FPS) compared to the original YOLOv7 model. In conclusion, the improved YOLOv7 network proposed in this study represents a promising solution for underwater target detection and holds great potential for practical applications in various underwater tasks. Full article
(This article belongs to the Section Ocean Engineering)
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22 pages, 9639 KB  
Article
Automated Atmospheric Correction of Nanosatellites Using Coincident Ocean Color Radiometer Data
by Sean McCarthy, Summer Crawford, Christopher Wood, Mark D. Lewis, Jason K. Jolliff, Paul Martinolich, Sherwin Ladner, Adam Lawson and Marcos Montes
J. Mar. Sci. Eng. 2023, 11(3), 660; https://doi.org/10.3390/jmse11030660 - 21 Mar 2023
Cited by 7 | Viewed by 3657
Abstract
Here we present a machine-learning-based method for utilizing traditional ocean-viewing satellites to perform automated atmospheric correction of nanosatellite data. These sensor convolution techniques are required because nanosatellites do not usually possess the wavelength combinations required to atmospherically correct upwelling radiance data for oceanographic [...] Read more.
Here we present a machine-learning-based method for utilizing traditional ocean-viewing satellites to perform automated atmospheric correction of nanosatellite data. These sensor convolution techniques are required because nanosatellites do not usually possess the wavelength combinations required to atmospherically correct upwelling radiance data for oceanographic applications; however, nanosatellites do provide superior ground-viewing spatial resolution (~3 m). Coincident multispectral data from the Suomi National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite (Suomi NPP VIIRS; referred to herein as “VIIRS”) were used to remove atmospheric contamination at each of the nanosatellite’s visible wavelengths to yield an estimate of spectral water-leaving radiance [Lw(l)], which is the basis for surface ocean optical products. Machine learning (ML) algorithms (KNN, decision tree regressors) were applied to determine relationships between Lw and top-of-atmosphere (Lt)/Rayleigh (Lr) radiances within VIIRS training data, and then applied to test cases for (1) the Marine Optical Buoy (MOBY) in Hawaii and (2) the AErosol RObotic Network Ocean Color (AERONET-OC), Venice, Italy. For the test cases examined, ML-based methods appeared to improve statistical results when compared to alternative dark spectrum fitting (DSF) methods. The results suggest that ML-based sensor convolution techniques offer a viable path forward for the oceanographic application of nanosatellite data streams. Full article
(This article belongs to the Special Issue New Frontiers in Ocean Color Remote Sensing: Novel Applications, Sensor Fusion, and Hyperspectral Sensing)
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25 pages, 21339 KB  
Article
Coastal Erosion Identification and Monitoring in the Patras Gulf (Greece) Using Multi-Discipline Approaches
by Nikolaos Depountis, Dionysios Apostolopoulos, Vasileios Boumpoulis, Dimitris Christodoulou, Athanassios Dimas, Elias Fakiris, Georgios Leftheriotis, Alexandros Menegatos, Konstantinos Nikolakopoulos, George Papatheodorou and Nikolaos Sabatakakis
J. Mar. Sci. Eng. 2023, 11(3), 654; https://doi.org/10.3390/jmse11030654 - 20 Mar 2023
Cited by 22 | Viewed by 7713
Abstract
The primary objective of this research is to demonstrate advanced surveying methods and techniques for coastal erosion identification and monitoring in a densely human-populated coastline, the southern coastline of the Gulf of Patras (Greece), which diachronically suffers erosion problems expected to become worse [...] Read more.
The primary objective of this research is to demonstrate advanced surveying methods and techniques for coastal erosion identification and monitoring in a densely human-populated coastline, the southern coastline of the Gulf of Patras (Greece), which diachronically suffers erosion problems expected to become worse in the forthcoming years due to climate change and human intervention. Its importance lies in the fact that it presents a robust methodology on how all modern scientific knowledge and techniques should be used in coastal erosion problems. The presented methods include the use of satellite and aerial photo imaging, shallow seabed bathymetry and morphology, sediment sampling, geotechnical investigations, as well as hydrodynamic modelling. The results are extensively analyzed in terms of their importance in coastal erosion studies and are cross-validated to define those areas most vulnerable to erosion. Towards this scope, the seabed erosion rate produced by hydrodynamic modelling is compared with the coastal vulnerability index (CVI) calculations performed in the examined area to identify which coastal zones are under a regime of intensive erosion. The results between the CVI and the seabed erosion rate appear to coincide in terms of the erosion potential, especially in zones where the vulnerability regime has been calculated as being high or very high, with the P. oceanica meadows playing an important role in reducing erosion. Full article
(This article belongs to the Special Issue Estuaries, Coasts, and Seas in a Changing Climate)
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17 pages, 16130 KB  
Article
Application of Buoyancy Support System to Secure Residual Buoyancy of Damaged Ships
by Gyeong Joong Lee, Jang-Pyo Hong, Kwang Keun Lee and Hee Jin Kang
J. Mar. Sci. Eng. 2023, 11(3), 656; https://doi.org/10.3390/jmse11030656 - 20 Mar 2023
Cited by 6 | Viewed by 5747
Abstract
SOLAS (Safety of Life at Sea), which was first enacted in 1914 as a result of the Titanic disaster, presents mandatory requirements for ship safety, such as the adoption of watertight bulkheads. However, ship accidents continue to occur despite the development and application [...] Read more.
SOLAS (Safety of Life at Sea), which was first enacted in 1914 as a result of the Titanic disaster, presents mandatory requirements for ship safety, such as the adoption of watertight bulkheads. However, ship accidents continue to occur despite the development and application of numerous safety technologies. In the case of a marine accident, the risk of sinking or capsizing due to flooding can be reduced by subdividing the watertight area, but shipbuilding costs, the weight increase for light ships, and the intact stability of the vessel must be considered together. For this reason, in this study, a BSS (buoyancy support system) was designed in accordance with ISO 23121-1 and ISO 23121-2. The characteristics of watertight and non-watertight spaces were reviewed and the BSS was implemented for a small car ferry. By applying additional safety technologies while securing economic feasibility in terms of ship construction and operation, an alternative to reduce the loss of human lives, environmental damage, and property losses in the case of a ship accident was proposed. Full article
(This article belongs to the Special Issue Damage Stability of Ships)
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15 pages, 5521 KB  
Article
On the Fatigue Strength of Welded High-Strength Steel Joints in the As-Welded, Post-Weld-Treated and Repaired Conditions in a Typical Ship Structural Detail
by Antti Ahola, Kalle Lipiäinen, Juuso Lindroos, Matti Koskimäki, Kari Laukia and Timo Björk
J. Mar. Sci. Eng. 2023, 11(3), 644; https://doi.org/10.3390/jmse11030644 - 19 Mar 2023
Cited by 21 | Viewed by 6376
Abstract
Weld quality and life extension methods of welded details in ship structures made of high-strength and ultra-high-strength steels are of high importance to overcome the issues related to the fatigue characteristics of welded high-strength steels. The current work experimentally and numerically investigated the [...] Read more.
Weld quality and life extension methods of welded details in ship structures made of high-strength and ultra-high-strength steels are of high importance to overcome the issues related to the fatigue characteristics of welded high-strength steels. The current work experimentally and numerically investigated the fatigue strength of a longitudinal stiffener detail, typically present in the bulkhead connections of ship hull. Two high-strength steel grades, namely EQ47TM and EQ70QT steels, were studied in welded plate connections using gas metal arc welding with rutile-cored wires. Fatigue tests were carried out on both small-scale specimens under axial and large-scale beam specimens under four-point bending loading. In addition to the joints tested in the as-welded condition, the high-frequency mechanical impact (HFMI) treatment was considered as a post-weld treatment technique in the fatigue test series. Furthermore, the large-scale beam specimens were pre-fatigued until substantial fatigue cracks were observed, after which they were re-tested after weld repairing and post-weld treatments to investigate the potential to rehabilitate fatigue-cracked ship details. The joints in the as-welded condition were performed in accordance with the current design recommendations. Due to the severe transition from the base material to the weld reinforcement in the joints welded with the rutile-cored wire, a successful HFMI treatment required geometrical modification of weld toe using a rotary burr to avoid any detrimental sub-cracks at the HFMI-treated region. Alternatively, the use of solid filler wires could potentially overcome these issues related to the welding quality. Repaired and post-weld-treated welds performed well in the re-tests, and the fatigue strength was almost twice higher than that of tests in the as-welded condition. Full article
(This article belongs to the Special Issue Fatigue and Fracture Mechanics of Marine Structures)
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26 pages, 6068 KB  
Article
Research on Position Sensorless Control of RDT Motor Based on Improved SMO with Continuous Hyperbolic Tangent Function and Improved Feedforward PLL
by Hongfen Bai, Bo Yu and Wei Gu
J. Mar. Sci. Eng. 2023, 11(3), 642; https://doi.org/10.3390/jmse11030642 - 17 Mar 2023
Cited by 24 | Viewed by 3661
Abstract
With the increasing use of electric propulsion ships, the emergence of the shaftless rim-driven thruster (RDT) as a revolutionary integrated motor thruster is gradually becoming an important development direction for green ships. The shaftless structure of RDTs leads to their dependence on position [...] Read more.
With the increasing use of electric propulsion ships, the emergence of the shaftless rim-driven thruster (RDT) as a revolutionary integrated motor thruster is gradually becoming an important development direction for green ships. The shaftless structure of RDTs leads to their dependence on position sensorless control techniques. In this study, a novel control algorithm using a composite sliding mode observer (SMO) with a modified feed-forward phase-locked loop (PLL) is presented for achieving high accuracy position and speed control of shaftless RDT motors. The deviation between the observed and actual currents is exploited to develop a current SMO to extract back electromotive force (back-EMF) errors. On this basis, a back-EMF observer is established to achieve accurate estimation of the back-EMF. The basic structure of the PLL was modified and incorporates a speed feedforward mechanism, which enhances the performance of rotor position estimation and facilitates bidirectional rotation. The stability of the algorithm has been verified in Matlab/Simulink for a range of steady-state, dynamic, and ship propeller loading conditions. Remarkably, the control algorithm boasts an impressive adjustment time of approximately 0.006 s and its position estimation error may be as low as 0.03 rad. Simulation results highlight the performance of the algorithm to achieve bidirectional rotation, while exhibiting fast convergence, minimal vibration, exceptional control accuracy, and robustness. Full article
(This article belongs to the Special Issue Application of Artificial Intelligence in Maritime Transportation)
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25 pages, 18299 KB  
Article
New Methodology for Shoreline Extraction Using Optical and Radar (SAR) Satellite Imagery
by Sara Zollini, Donatella Dominici, Maria Alicandro, María Cuevas-González, Eduard Angelats, Francesca Ribas and Gonzalo Simarro
J. Mar. Sci. Eng. 2023, 11(3), 627; https://doi.org/10.3390/jmse11030627 - 16 Mar 2023
Cited by 45 | Viewed by 7664
Abstract
Coastal environments are dynamic ecosystems, constantly subject to erosion/accretion processes. Erosional trends have unfortunately been intensifying for decades due to anthropic factors and an accelerated sea level rise might exacerbate the problem. It is crucial to preserve these areas for safeguarding not only [...] Read more.
Coastal environments are dynamic ecosystems, constantly subject to erosion/accretion processes. Erosional trends have unfortunately been intensifying for decades due to anthropic factors and an accelerated sea level rise might exacerbate the problem. It is crucial to preserve these areas for safeguarding not only coastal ecosystems and cultural heritage, but also the population living there. In this context, monitoring coastal areas is essential and geomatics techniques, especially satellite remote sensing imagery, might prove very advantageous. In this paper, a semi-automatic methodology to extract shorelines from SAR (Synthetic Aperture Radar) Sentinel-1 and optical Sentinel-2 satellite images was developed. An experimental algorithm, called J-Net Dynamic, was tested in two pilot sites. The semi-automatic methodology was validated with GNSS (Global Navigation Satellite System) reference shorelines and demonstrated to be a powerful tool for a robust extraction of the shoreline both from optical and SAR images. The experimental algorithm was able to extract the shoreline closer to the reference with SAR images on the natural beach of Castelldefels and it was demonstrated to be less sensitive to speckle effects than the commonly used Canny Edge Detector. Using the SAR images of the urban beach of Somorrostro, the Canny detector was not able to extract the shoreline, while the new algorithm could do it but with low accuracy because of the noise induced by man-made structures. For further investigation, the Sentinel-2-extracted shorelines were also compared to the ones extracted by a state-of-the-art tool, CoastSat, in the two beaches using both automatic and manual thresholds. The mean errors obtained with J-Net Dynamic were generally higher than the ones from CoastSat using the manual threshold but lower if using the automatic one. The proposed methodology including the J-Net Dynamic algorithm proves to extract the shorelines closer to the reference in most of the cases and offers the great advantage of being able to work with both optical and SAR images. This feature could allow to reduce the time lag between satellite derived shorelines paving the way to an enhanced monitoring and management of coastal areas. Full article
(This article belongs to the Special Issue Remote Sensing for Coastal Management)
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14 pages, 5525 KB  
Article
Image Dataset for Neural Network Performance Estimation with Application to Maritime Ports
by Miro Petković, Igor Vujović, Zvonimir Lušić and Joško Šoda
J. Mar. Sci. Eng. 2023, 11(3), 578; https://doi.org/10.3390/jmse11030578 - 8 Mar 2023
Cited by 16 | Viewed by 7135
Abstract
Automated surveillance systems based on machine learning and computer vision constantly evolve to improve shipping and assist port authorities. The data obtained can be used for port and port property surveillance, traffic density analysis, maritime safety, pollution assessment, etc. However, due to the [...] Read more.
Automated surveillance systems based on machine learning and computer vision constantly evolve to improve shipping and assist port authorities. The data obtained can be used for port and port property surveillance, traffic density analysis, maritime safety, pollution assessment, etc. However, due to the lack of datasets for video surveillance and ship classification in real maritime zones, there is a need for a reference dataset to compare the obtained results. This paper presents a new dataset for estimating detection and classification performance which provides versatile ship annotations and classifications for passenger ports with a large number of small- to medium-sized ships that were not monitored by the automatic identification system (AIS) and/or the vessel traffic system (VTS). The dataset is considered general for the Mediterranean region since many ports have a similar maritime traffic configuration as the Port of Split, Croatia. The dataset consists of 19,337 high-resolution images with 27,849 manually labeled ship instances classified into 12 categories. The vast majority of the images contain the port and starboard sides of the ships. In addition, the images were acquired in a real maritime zone at different times of the year, day, weather conditions, and sea state conditions. Full article
(This article belongs to the Section Ocean Engineering)
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19 pages, 17413 KB  
Article
Past Analogues of Deoxygenation Events in the Mediterranean Sea: A Tool to Constrain Future Impacts
by Alan Maria Mancini, Giacomo Bocci, Caterina Morigi, Rocco Gennari, Francesca Lozar and Alessandra Negri
J. Mar. Sci. Eng. 2023, 11(3), 562; https://doi.org/10.3390/jmse11030562 - 6 Mar 2023
Cited by 14 | Viewed by 5149
Abstract
Human-induced carbon emissions are altering the modern climate, with severe repercussions on ecosystems. Among others, anthropogenic pressure is causing deoxygenation of the bottom water, with the widespread establishment of hypoxic zones in several Mediterranean areas. The geological archives allow investigating past deoxygenation dynamics [...] Read more.
Human-induced carbon emissions are altering the modern climate, with severe repercussions on ecosystems. Among others, anthropogenic pressure is causing deoxygenation of the bottom water, with the widespread establishment of hypoxic zones in several Mediterranean areas. The geological archives allow investigating past deoxygenation dynamics (sapropel events) and their impact on marine ecosystems. Here, we compare the causes and the evolution of deoxygenation dynamics which occurred during two different time periods (Messinian and Holocene) in different paleoceanographic settings based on their micropaleontological content. The Messinian sapropel events are the result of increased export productivity during a relatively cold and arid context, triggering bottom anoxic conditions. The Holocene sapropel formed in response to weakening/stopping of the thermohaline circulation due to increasing temperature and freshwater input. Our results suggest that the deoxygenation dynamics in the Mediterranean in the near future will not follow the trend characteristic of the Holocene deep-sea sapropel because of the predicted drying trend. Differently, the paleoceanographic setting triggering the Messinian shallow-sea sapropels is comparable with the modern situation in different Mediterranean areas, where human-induced eutrophication is promoting deoxygenation. Based on these results, we suggest that the patchy deoxygenation trend in the Mediterranean Sea caused by climate warming may lead to a drastic change in the ecosystem services which would likely impact human activities. Full article
(This article belongs to the Special Issue Editorial Board Members’ Collection Series “Paleoecology and Paleoenvironment Reconstruction”)
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22 pages, 3038 KB  
Article
Proposal of Zero-Emission Tug in South Korea Using Fuel Cell/Energy Storage System: Economic and Environmental Long-Term Impacts
by Kyunghwa Kim, Kido Park, Gilltae Roh, Choungho Choung, Kyuhyeong Kwag and Wook Kim
J. Mar. Sci. Eng. 2023, 11(3), 540; https://doi.org/10.3390/jmse11030540 - 2 Mar 2023
Cited by 15 | Viewed by 4853
Abstract
This study presents the results of economic and environmental analysis for two types of zero-emission ships (ZESs) that are receiving more attention to meet strengthened environmental regulations. One of the two types of ZES is the ZES using only the energy storage system [...] Read more.
This study presents the results of economic and environmental analysis for two types of zero-emission ships (ZESs) that are receiving more attention to meet strengthened environmental regulations. One of the two types of ZES is the ZES using only the energy storage system (All-ESS), and the other is the ZES with fuel cell and ESS hybrid system (FC–ESS). The target ship is a tug operating in South Korea, and the main parameters are based on the specific circumstances of South Korea. The optimal capacity of the ESS for each proposed system is determined using an optimization tool. The total cost for a ship’s lifetime is calculated using economic analysis. The greenhouse gas (GHG) emission for the fuel’s lifecycle (well-to-wake) is calculated using environmental analysis. The results reveal that the proposed ZESs are 1.7–3.4 times more expensive than the conventional marine gas oil (MGO)-fueled ship; however, it could be reduced by 1.3–2.4 times if the carbon price is considered. The proposed ZESs have 58.7–74.3% lower lifecycle GHG emissions than the one from the conventional ship. The results also highlight that the electricity- or hydrogen-based ZESs should reduce GHG emissions from the upstream phase (well-to-tank) to realize genuine ZESs. Full article
(This article belongs to the Special Issue Decarbonization of Ship Power Plants)
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24 pages, 1700 KB  
Article
Trajectory Tracking Nonlinear Controller for Underactuated Underwater Vehicles Based on Velocity Transformation
by Przemyslaw Herman
J. Mar. Sci. Eng. 2023, 11(3), 509; https://doi.org/10.3390/jmse11030509 - 26 Feb 2023
Cited by 11 | Viewed by 2902
Abstract
This paper proposes an algorithm that performs the task of tracking the desired trajectory for underactuated marine vehicles (primarily underwater) that move horizontally. The control scheme, which takes into account model inaccuracies and external disturbances, was designed using the quantities obtained after the [...] Read more.
This paper proposes an algorithm that performs the task of tracking the desired trajectory for underactuated marine vehicles (primarily underwater) that move horizontally. The control scheme, which takes into account model inaccuracies and external disturbances, was designed using the quantities obtained after the transformation of the dynamic equations of motion resulting from the decomposition of the inertia matrix. This, in turn, led to the equation of dynamics with a diagonal inertia matrix. A specific feature of the offered controller is its dual role. It not only allows tracking the desired trajectory, but at the same time, makes it possible to estimate the impact of dynamic couplings when the vehicle is in motion. Such an approach to the tracking task is important at the initial design stage when the choice of the control algorithm has not yet been decided and experimental tests have not been performed. This is feasible because the new variables after the velocity transformation include not only vehicle parameters, but also actual velocities and forces. Therefore, it is also possible to track the original variables. The theoretical results were followed up with simulation tests conducted on a model with three degrees of freedom for two underwater vehicles. Full article
(This article belongs to the Special Issue Advances in Marine Vehicles, Automation and Robotics)
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14 pages, 1861 KB  
Article
UMGAN: Underwater Image Enhancement Network for Unpaired Image-to-Image Translation
by Boyang Sun, Yupeng Mei, Ni Yan and Yingyi Chen
J. Mar. Sci. Eng. 2023, 11(2), 447; https://doi.org/10.3390/jmse11020447 - 17 Feb 2023
Cited by 66 | Viewed by 6985
Abstract
Due to light absorption and scattering underwater images suffer from low contrast, color distortion, blurred details, and uneven illumination, which affect underwater vision tasks and research. Therefore, underwater image enhancement is of great significance in vision applications. In contrast to existing methods for [...] Read more.
Due to light absorption and scattering underwater images suffer from low contrast, color distortion, blurred details, and uneven illumination, which affect underwater vision tasks and research. Therefore, underwater image enhancement is of great significance in vision applications. In contrast to existing methods for specific underwater environments or reliance on paired datasets, this study proposes an underwater multiscene generative adversarial network (UMGAN) to enhance underwater images. The network implements unpaired image-to-image translation between the underwater turbid domain and the underwater clear domain. It has a great enhancement impact on several underwater image types. Feedback mechanisms and a noise reduction network are designed to optimize the generator and address the issue of noise and artifacts in GAN-produced images. Furthermore, a global–local discriminator is employed to improve the overall image while adaptively modifying the local region image effect. It resolves the issue of over- and underenhancement in local regions. The reliance on paired training data is eliminated through a cycle consistency network structure. UMGAN performs satisfactorily on various types of data when compared quantitatively and qualitatively to other state-of-the-art algorithms. It has strong robustness and can be applied to various enhancement tasks in different scenes. Full article
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17 pages, 3099 KB  
Article
Discerning Discretization for Unmanned Underwater Vehicles DC Motor Control
by Jovan Menezes and Timothy Sands
J. Mar. Sci. Eng. 2023, 11(2), 436; https://doi.org/10.3390/jmse11020436 - 16 Feb 2023
Cited by 21 | Viewed by 4703
Abstract
Discretization is the process of converting a continuous function or model or equation into discrete steps. In this work, learning and adaptive techniques are implemented to control DC motors that are used for actuating control surfaces of unmanned underwater vehicles. Adaptive control is [...] Read more.
Discretization is the process of converting a continuous function or model or equation into discrete steps. In this work, learning and adaptive techniques are implemented to control DC motors that are used for actuating control surfaces of unmanned underwater vehicles. Adaptive control is a strategy wherein the controller is designed to adapt the system with parameters that vary or are uncertain. Parameter estimation is the process of computing the parameters of a system using a model and measured data. Adaptive methods have been used in conjunction with different parameter estimation techniques. As opposed to the ubiquitous stochastic artificial intelligence approaches, very recently proposed deterministic artificial intelligence, a learning-based approach that uses the physics-defined process dynamics, is also applied to control the output of the DC motor to track a specified trajectory. This work goes further to evaluate the performance of the adaptive and learning techniques based on different discretization methods. The results are evaluated based on the absolute error mean between the output and the reference trajectory and the standard deviation of the error. The first-order hold method of discretization and surprisingly large sample time of seven-tenths of a second yields greater than sixty percent improvement over the results presented in the prequel literature. Full article
(This article belongs to the Special Issue Autonomous Underwater Vehicle Technology Advances in Ocean Observation)
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25 pages, 12570 KB  
Article
Optimal SOC Control and Rule-Based Energy Management Strategy for Fuel-Cell-Based Hybrid Vessel including Batteries and Supercapacitors
by Zeyu Ma, Hao Chen, Jingang Han, Yizheng Chen, Jiongchen Kuang, Jean-Frédéric Charpentier, Nadia Aϊt-Ahmed and Mohamed Benbouzid
J. Mar. Sci. Eng. 2023, 11(2), 398; https://doi.org/10.3390/jmse11020398 - 10 Feb 2023
Cited by 36 | Viewed by 4289
Abstract
Around the world, the development of electric vehicles is underway, including in maritime transportation. However, the development of clean energy vessels still has a long way to go. Fuel cells (FCs) are a relevant choice among the many clean energy sources to power [...] Read more.
Around the world, the development of electric vehicles is underway, including in maritime transportation. However, the development of clean energy vessels still has a long way to go. Fuel cells (FCs) are a relevant choice among the many clean energy sources to power clean energy vessels. However, due to the complex and drastic change in the shipload power, FCs need to be equipped with dynamic fast-response energy storage equipment to make up for it. For multiple energy storage devices connected in parallel, the state of charge (SOC) is not balanced, which affects their service life and the stability of the vessel microgrid, as well as slowing the speed and lowering the accuracy of SOC equalization. This paper proposes a distributed variable sag slope control strategy for vessels to improve SOC equalization, with a FC as the energy source and a battery and supercapacitor as the energy storage system (ESS). For the output power distribution problem of energy storage equipment caused by shipload power variation, a power distribution strategy with a variable filter time constant is used to improve the reasonableness of the output power distribution of energy-based lithium batteries and power-based supercapacitors. Meanwhile, this paper considers the power generation equipment’s service life and energy cost as the optimization objectives, considering the discharge depth of the energy storage equipment. Finally, a method based on the combination of the lithium battery SOC rule (the rule formulated according to the state of charge and load power change in energy storage equipment) and particle swarm optimization algorithm is proposed to solve this problem. The simulation results show that the proposed strategy improves the equalization speed and accuracy of the SOC of energy storage devices, fully realizes the characteristics of different energy storage devices, and reduces the life loss of energy storage devices. Full article
(This article belongs to the Special Issue Advanced Research in Innovative Ship Energy Systems)
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12 pages, 3230 KB  
Article
Stress–Strain Assessment of Honeycomb Sandwich Panel Subjected to Uniaxial Compressive Load
by Pasqualino Corigliano, Giulia Palomba, Vincenzo Crupi and Yordan Garbatov
J. Mar. Sci. Eng. 2023, 11(2), 365; https://doi.org/10.3390/jmse11020365 - 6 Feb 2023
Cited by 10 | Viewed by 3895
Abstract
The ship hull structure is composed of plates and stiffened panels. Estimating the maximum load-carrying capacity, or the ultimate strength, of these structural components is fundamental. One of the main challenges nowadays is the implementation of new materials and technologies to enhance the [...] Read more.
The ship hull structure is composed of plates and stiffened panels. Estimating the maximum load-carrying capacity, or the ultimate strength, of these structural components is fundamental. One of the main challenges nowadays is the implementation of new materials and technologies to enhance the structural integrity, economy, safety and environmentally friendly design of the ship’s hull structure. A new design solution may be represented by aluminium alloy honeycomb sandwich structures, both as plane panels or stiffened ones, which are characterised by excellent impact-absorption capabilities and a high stiffness-to-weight ratio. Still, their response to some conditions typical of ship structural design needs to be deeply investigated. Axial compressive loading is one of the most critical conditions that could impact the structural integrity of such light-weight solutions. Hence, the uniaxial compressive behaviour of aluminium honeycomb sandwich structures has to be deeply investigated to promote their integration in ship structural design. Within this context, the present work performs an experimental and numerical study of a honeycomb sandwich panel subjected to uniaxial compressive loads. The results will help develop models for predicting the uniaxial compressive load-carrying capacity of hybrid honeycomb sandwiches of aluminium alloy design. Full article
(This article belongs to the Special Issue Lightweight and Additively Manufactured Structures in Marine Applications)
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13 pages, 13408 KB  
Article
Sediment Erosion Generated by a Coandă-Effect-Based Polymetallic-Nodule Collector
by Said Alhaddad and Rudy Helmons
J. Mar. Sci. Eng. 2023, 11(2), 349; https://doi.org/10.3390/jmse11020349 - 4 Feb 2023
Cited by 32 | Viewed by 3737
Abstract
To date, hydraulic collection is the most widely considered technology in polymetallic-nodule mining, since there is no direct contact between hydraulic collectors and ocean floor. To construct a hydraulic collector that results in the least sediment disturbance, it is critical to develop an [...] Read more.
To date, hydraulic collection is the most widely considered technology in polymetallic-nodule mining, since there is no direct contact between hydraulic collectors and ocean floor. To construct a hydraulic collector that results in the least sediment disturbance, it is critical to develop an insightful understanding of the interaction between the collector and sediment bed. To this end, we conducted a set of small-scale experiments in which several operational conditions were tested, delivering the first quantitative data for sediment erosion resulting from a hydraulic collector driving over a sand bed. This paper presents and discusses the experimental results and observations. It is found that the collector’s forward velocity is inversely proportional to the bed-sediment erosion depth, since the bed is exposed to the flow for a longer time when the collector drives slower and vice versa. In contrast, an increased jet velocity leads to a larger erosion depth. Furthermore, when the collector underside is nearer to the sediment bed, a larger sediment layer is exposed to the water flow, resulting in a larger erosion depth. Finally, the experimental results show that collector water jets strike the sediment bed under an inclined angle, destabilizing the upper sediment layer and consequently dragging sediment particles along toward the collection duct and behind the collector head. This study improves the predictability of sediment erosion created by Coandă-effect-based collectors, which is a crucial asset to optimize the collector design and decrease the extent of the associated sediment plumes. Full article
(This article belongs to the Section Ocean Engineering)
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38 pages, 2639 KB  
Review
Reconstruction Methods in Oceanographic Satellite Data Observation—A Survey
by Leon Ćatipović, Frano Matić and Hrvoje Kalinić
J. Mar. Sci. Eng. 2023, 11(2), 340; https://doi.org/10.3390/jmse11020340 - 3 Feb 2023
Cited by 23 | Viewed by 5205
Abstract
Oceanographic parameters, such as sea surface temperature, surface chlorophyll-a concentration, sea surface ice concentration, sea surface height, etc., are listed as Essential Climate Variables. Therefore, there is a crucial need for persistent and accurate measurements on a global scale. While in situ methods [...] Read more.
Oceanographic parameters, such as sea surface temperature, surface chlorophyll-a concentration, sea surface ice concentration, sea surface height, etc., are listed as Essential Climate Variables. Therefore, there is a crucial need for persistent and accurate measurements on a global scale. While in situ methods tend to be accurate and continuous, these qualities are difficult to scale spatially, leaving a significant portion of Earth’s oceans and seas unmonitored. To tackle this, various remote sensing techniques have been developed. One of the more prominent ways to measure the aforementioned parameters is via satellite spacecraft-mounted remote sensors. This way, spatial coverage is considerably increased while retaining significant accuracy and resolution. Unfortunately, due to the nature of electromagnetic signals, the atmosphere itself and its content (such as clouds, rain, etc.) frequently obstruct the signals, preventing the satellite-mounted sensors from measuring, resulting in gaps—missing data—in satellite recordings. One way to deal with these gaps is via various reconstruction methods developed through the past two decades. However, there seems to be a lack of review papers on reconstruction methods for satellite-derived oceanographic variables. To rectify the lack, this paper surveyed more than 130 articles dealing with the issue of data reconstruction. Articles were chosen according to two criteria: (a) the article has to feature satellite-derived oceanographic data (b) gaps in satellite data have to be reconstructed. As an additional result of the survey, a novel categorising system based on the type of input data and the usage of time series in reconstruction efforts is proposed. Full article
(This article belongs to the Special Issue Recent Scientific Developments in Ocean Observation)
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24 pages, 15787 KB  
Article
Influence of Wave–Current Interaction on a Cyclone-Induced Storm Surge Event in the Ganges–Brahmaputra–Meghna Delta: Part 1—Effects on Water Level
by Md Wasif E Elahi, Xiao Hua Wang, Julio Salcedo-Castro and Elizabeth A. Ritchie
J. Mar. Sci. Eng. 2023, 11(2), 328; https://doi.org/10.3390/jmse11020328 - 2 Feb 2023
Cited by 19 | Viewed by 5226
Abstract
The Ganges–Brahmaputra–Meghna Delta (GBMD) located in the head of the Bay of Bengal is regularly affected by severe tropical cyclones frequently. The GBMD covers the Bangladesh coast, which is one of the most vulnerable areas in the world due to cyclone-induced storm surges. [...] Read more.
The Ganges–Brahmaputra–Meghna Delta (GBMD) located in the head of the Bay of Bengal is regularly affected by severe tropical cyclones frequently. The GBMD covers the Bangladesh coast, which is one of the most vulnerable areas in the world due to cyclone-induced storm surges. More than 30% of the total country’s population lives on the Bangladesh coast. Hence, it is crucial to understand the underlying processes that modulate the storm surge height in the GBMD. A barotropic numerical 3D model setup is established by using Delft3D and SWAN to investigate a cyclone-induced storm surge event. The model is calibrated and validated for Cyclone Sidr in 2007 and applied to six idealized cyclonic scenarios. Numerical experiments with different coupling configurations are performed to distinguish the contribution of wind, tides, waves, and wave–current interactions (WCI) on the storm surge height. Results show that the wind-driven setup is the dominant contributor to the storm surge height during cyclonic events. Based on the tidal phase and wind direction, the interaction between tide and wind can increase or decrease the magnitude of the storm surge height. Finally, considering the wind-driven wave may increase the surge height up to 0.3 m along the coastline through a strong wave setup. Full article
(This article belongs to the Special Issue Numerical Modelling of Atmospheres and Oceans)
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21 pages, 3963 KB  
Review
Southern Ocean Iron Limitation of Primary Production between Past Knowledge and Future Projections
by Emma Bazzani, Chiara Lauritano and Maria Saggiomo
J. Mar. Sci. Eng. 2023, 11(2), 272; https://doi.org/10.3390/jmse11020272 - 25 Jan 2023
Cited by 25 | Viewed by 9144
Abstract
Primary production in the Southern Ocean highly depends on phytoplankton and has been reported to be limited by the availability of the micronutrient iron. The aim of this review is to summarize the past and current knowledge on iron limitation in the Southern [...] Read more.
Primary production in the Southern Ocean highly depends on phytoplankton and has been reported to be limited by the availability of the micronutrient iron. The aim of this review is to summarize the past and current knowledge on iron limitation in the Southern Ocean, and specifically how it affects primary producers, thus influencing the whole Southern Ocean community structure, carbon cycling, and large-scale ocean biogeochemistry. In this region, extensive variability exists between different areas regarding iron availability, but also between seasons. Moreover, co-limitations with other abiotic environmental factors exist, further complicating the assessment of the role of iron as limiting factor for phytoplankton productivity. Currently, climate change is altering the Southern Ocean environment. How these changes will affect resident phytoplankton is still not clear, possibly modifying the iron supply mechanisms. Existing projections point towards a possible partial relief of iron stress on phytoplankton, but the interactions between different environmental changes, and the cascade effects they will have, are still poorly understood, and some aspects understudied. Here we try to synthetize the available predictions and uncertainties concerning this topic. Full article
(This article belongs to the Special Issue Biodiversity, Adaptation Strategies, and Opportunities in Extreme Marine Environments)
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15 pages, 4650 KB  
Article
Intelligent Model for Dynamic Shear Modulus and Damping Ratio of Undisturbed Marine Clay Based on Back-Propagation Neural Network
by Qi Wu, Zifan Wang, You Qin and Wenbao Yang
J. Mar. Sci. Eng. 2023, 11(2), 249; https://doi.org/10.3390/jmse11020249 - 19 Jan 2023
Cited by 28 | Viewed by 3971
Abstract
In this study, a series of resonant-column experiments were conducted on marine clays from Bohai Bay and Hangzhou Bay, China. The characteristics of the dynamic shear modulus (G) and damping ratio (D) of these marine clays were examined. It [...] Read more.
In this study, a series of resonant-column experiments were conducted on marine clays from Bohai Bay and Hangzhou Bay, China. The characteristics of the dynamic shear modulus (G) and damping ratio (D) of these marine clays were examined. It was found that G and D not only vary with shear strain (γ), but they also have a strong connection with soil depth (H) (reflected by the mean effective confining pressure (σm) in the laboratory test conditions). With increasing H (σm) and fixed γ, the value of G gradually increases; conversely, the value of D gradually decreases, and this is accompanied by the weakening of the decay or growth rate. An intelligent model based on a back-propagation neural network (BPNN) was developed for the calculation of these parameters. Compared with existing function models, the proposed intelligent model avoids the forward propagation of data errors and the need for human intervention regarding the fitting parameters. The model can accurately predict the G and D characteristics of marine clays at different H (σm) and the corresponding γ. The prediction accuracy is universal and does not strictly depend on the number of neurons in the hidden layer of the neural network. Full article
(This article belongs to the Special Issue Advance in Marine Geotechnical Engineering)
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29 pages, 10093 KB  
Article
Field Measurement and Numerical Study on the Effects of Under-Excavation and Over-Excavation on Ultra-Deep Foundation Pit in Coastal Area
by Jifei Cui, Zhenkun Yang and Rafig Azzam
J. Mar. Sci. Eng. 2023, 11(1), 219; https://doi.org/10.3390/jmse11010219 - 14 Jan 2023
Cited by 40 | Viewed by 5075
Abstract
An ultra-deep L-shape foundation pit in a coastal area has recently been constructed and monitored. The project overview, geological conditions, excavation sequence and monitoring scheme are introduced in detail. The deformation of the retaining structure and surrounding strata are analyzed in detail through [...] Read more.
An ultra-deep L-shape foundation pit in a coastal area has recently been constructed and monitored. The project overview, geological conditions, excavation sequence and monitoring scheme are introduced in detail. The deformation of the retaining structure and surrounding strata are analyzed in detail through the measured data and 3D numerical simulation. The results show that the exceptional performance of the current project is due to the combination of under-excavation and over-excavation during construction. The under-excavation procedure restrained the wall deflections at the middle part of the diaphragm wall, making the corner effects at the corresponding side inapparent. Both the under-excavation and over-excavation procedure can only influence the performance of the excavation in close proximity, while having negligible impacts on the normally excavated areas. Based on the results of this study, practical suggestions are given to improve the performance of similar excavations in the future. Full article
(This article belongs to the Special Issue Advances in Offshore Geotechnics)
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15 pages, 764 KB  
Article
Deep Learning-Based Ship Speed Prediction for Intelligent Maritime Traffic Management
by Sara El Mekkaoui, Loubna Benabbou, Stéphane Caron and Abdelaziz Berrado
J. Mar. Sci. Eng. 2023, 11(1), 191; https://doi.org/10.3390/jmse11010191 - 12 Jan 2023
Cited by 47 | Viewed by 9088
Abstract
Improving maritime operations planning and scheduling can play an important role in enhancing the sector’s performance and competitiveness. In this context, accurate ship speed estimation is crucial to ensure efficient maritime traffic management. This study addresses the problem of ship speed prediction from [...] Read more.
Improving maritime operations planning and scheduling can play an important role in enhancing the sector’s performance and competitiveness. In this context, accurate ship speed estimation is crucial to ensure efficient maritime traffic management. This study addresses the problem of ship speed prediction from a Maritime Vessel Services perspective in an area of the Saint Lawrence Seaway. The challenge is to build a real-time predictive model that accommodates different routes and vessel types. This study proposes a data-driven solution based on deep learning sequence methods and historical ship trip data to predict ship speeds at different steps of a voyage. It compares three different sequence models and shows that they outperform the baseline ship speed rates used by the VTS. The findings suggest that deep learning models combined with maritime data can leverage the challenge of estimating ship speed. The proposed solution could provide accurate and real-time estimations of ship speed to improve shipping operational efficiency, navigation safety and security, and ship emissions estimation and monitoring. Full article
(This article belongs to the Section Ocean Engineering)
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19 pages, 1898 KB  
Article
Optimization of Maintenance Schedule for Containerships Sailing in the Adriatic Sea
by Nastia Degiuli, Andrea Farkas, Ivana Martić and Carlo Giorgio Grlj
J. Mar. Sci. Eng. 2023, 11(1), 201; https://doi.org/10.3390/jmse11010201 - 12 Jan 2023
Cited by 19 | Viewed by 4004
Abstract
Biofouling attaches to immersed surfaces in between hull cleanings. Due to high speeds and relatively short port times, biofilm often attaches to the immersed surfaces of containerships. In most cases, this type of fouling is not given much importance since it is assumed [...] Read more.
Biofouling attaches to immersed surfaces in between hull cleanings. Due to high speeds and relatively short port times, biofilm often attaches to the immersed surfaces of containerships. In most cases, this type of fouling is not given much importance since it is assumed that it will not cause any fouling penalties. In this paper, the fouling penalties related to fouling with biofilm on the example of the Post Panamax and Post Panamax Plus containership fleets sailing in the Adriatic Sea are assessed. In addition, the investigation is performed for real environmental conditions that a containership can encounter on a sailing route passing through the Adriatic Sea. Thus, the impact of waves and wind is taken into account based on mean values of significant wave height and wind speed for containerships sailing at the design speed along the analyzed route. The procedure for the determination of the detrimental effects of biofilm on the increase in fuel consumption and carbon dioxide emissions is given. Further, the proposed procedure includes the determination of calm water resistance by the Holtrop and Mennen method, the added resistance in waves by Liu and Papanikolaou’s method, spectral analysis using the Tabain’s spectrum for the Adriatic Sea, the wind resistance by the Blendermann method, and added resistance due to biofouling using the Granville method. Thereafter, a time-dependent biofouling growth model proposed by Uzun et al. is incorporated, and the adequate timing for underwater hull cleaning is determined for several hull cleaning costs. The obtained results demonstrate that, from an environmental point of view, proactive hull cleaning should be applied, while, from an economic perspective, optimal timing for underwater hull cleaning is recommended. Full article
(This article belongs to the Section Ocean Engineering)
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16 pages, 3079 KB  
Article
The Construction and Application of Dual-Objective Optimal Speed Model of Liners in a Changing Climate: Taking Yang Ming Route as an Example
by Jinxing Lu, Xianhua Wu and You Wu
J. Mar. Sci. Eng. 2023, 11(1), 157; https://doi.org/10.3390/jmse11010157 - 9 Jan 2023
Cited by 26 | Viewed by 3388
Abstract
In a changing climate, ship speed optimization plays an important role in energy conservation and emission reduction. In order to establish a dual-objective optimization model of minimizing ship operating costs and reducing carbon emissions, fuel costs, berthing costs, emission costs and fixed cost [...] Read more.
In a changing climate, ship speed optimization plays an important role in energy conservation and emission reduction. In order to establish a dual-objective optimization model of minimizing ship operating costs and reducing carbon emissions, fuel costs, berthing costs, emission costs and fixed cost during sailing cycles, the emission reduction strategies of ships using MGO in emission control areas and the AMP in ports are taken into account. The PSO algorithm is adopted to find the Pareto solution set, and the TOPSIS algorithm is used to screen the optimal compromise solution, while Yang Ming, a trans-Pacific route, is selected to verify the applicability of the model. The result shows that the optimization model can effectively reduce the operating cost during sailing cycles and control carbon emissions, which can provide references for ship operation decision-making to achieve carbon peaking and carbon neutrality. Full article
(This article belongs to the Special Issue State-of-the-Art in Maritime Safety and Smart Shipping)
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32 pages, 5289 KB  
Review
Recent Advances, Future Trends, Applications and Challenges of Internet of Underwater Things (IoUT): A Comprehensive Review
by Syed Agha Hassnain Mohsan, Yanlong Li, Muhammad Sadiq, Junwei Liang and Muhammad Asghar Khan
J. Mar. Sci. Eng. 2023, 11(1), 124; https://doi.org/10.3390/jmse11010124 - 6 Jan 2023
Cited by 179 | Viewed by 22943
Abstract
Oceans cover more than 70% of the Earth’s surface. For various reasons, almost 95% of these areas remain unexplored. Underwater wireless communication (UWC) has widespread applications, including real-time aquatic data collection, naval surveillance, natural disaster prevention, archaeological expeditions, oil and gas exploration, shipwreck [...] Read more.
Oceans cover more than 70% of the Earth’s surface. For various reasons, almost 95% of these areas remain unexplored. Underwater wireless communication (UWC) has widespread applications, including real-time aquatic data collection, naval surveillance, natural disaster prevention, archaeological expeditions, oil and gas exploration, shipwreck exploration, maritime security, and the monitoring of aquatic species and water contamination. The promising concept of the Internet of Underwater Things (IoUT) is having a great influence in several areas, for example, in small research facilities and average-sized harbors, as well as in huge unexplored areas of ocean. The IoUT has emerged as an innovative technology with the potential to develop a smart ocean. The IoUT framework integrates different underwater communication techniques such as optical, magnetic induction, and acoustic signals. It is capable of revolutionizing industrial projects, scientific research, and business. The key enabler technology for the IoUT is the underwater wireless sensor network (UWSN); however, at present, this is characterized by limitations in reliability, long propagation delays, high energy consumption, a dynamic topology, and limited bandwidth. This study examines the literature to identify potential challenges and risks, as well as mitigating solutions, associated with the IoUT. Our findings reveal that the key contributing elements to the challenges facing the IoUT are underwater communications, energy storage, latency, mobility, a lack of standardization, transmission media, transmission range, and energy constraints. Furthermore, we discuss several IoUT applications while highlighting potential future research directions. Full article
(This article belongs to the Special Issue Underwater Sensing, Signal Processing and Communications)
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25 pages, 8266 KB  
Article
Survey on Low-Cost Underwater Sensor Networks: From Niche Applications to Everyday Use
by Filippo Campagnaro, Fabian Steinmetz and Bernd-Christian Renner
J. Mar. Sci. Eng. 2023, 11(1), 125; https://doi.org/10.3390/jmse11010125 - 6 Jan 2023
Cited by 72 | Viewed by 14679
Abstract
Traditionally, underwater acoustic modems and positioning systems were developed for military and Oil & Gas industries, that require deep water deployments and extremely reliable systems, focusing on high power expensive systems and leaving the use of low-cost devices only attractive for academic studies. [...] Read more.
Traditionally, underwater acoustic modems and positioning systems were developed for military and Oil & Gas industries, that require deep water deployments and extremely reliable systems, focusing on high power expensive systems and leaving the use of low-cost devices only attractive for academic studies. Conversely, recent developments of low-cost unmanned vehicles, such as remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs), suitable for shallow water coastal missions, and the need of sensors network deployments for measuring water quality and studying the effect of climate change in coastal areas, called to the need of low-cost and low-power acoustic modems and positioning systems that are gaining more and more momentum to date. The use of these devices can enable a wide set of applications, often based on low-cost AUV swarm formations, where an acoustic link between the vehicles is required to coordinate the mission, perform the maneuvers, and maintain the formation along the time. Moreover, they can make environmental wireless sensor deployment cost effective by substituting wired systems. Underwater positioning systems, usually used in large-scale operations, can be finally applied to small-scale application thanks to the reduction in costs, at the price of a lower transmission and positioning range and precision. While in open-sea application this performance reduction is a huge limitation, in river, lagoon, port and lake deployments this is not an issue, given that the extremely shallow water and the presence of many obstacles would deteriorate the acoustic signal anyway, not allowing long range transmissions even with expensive and sophisticated acoustic devices. In this paper, we review the recent developments of low-cost and low-power acoustic communication and positioning systems, both analyzing University prototypes and new commercial devices available in the market, identifying advantages and limitations of these devices, and we describe potential new applications that can be enabled by these systems. Full article
(This article belongs to the Special Issue New Challenges in Autonomous Underwater Networks)
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23 pages, 3687 KB  
Article
Wind-Assisted Ship Propulsion of a Series 60 Ship Using a Static Kite Sail
by Wayne Formosa, Tonio Sant, Claire De Marco Muscat-Fenech and Massimo Figari
J. Mar. Sci. Eng. 2023, 11(1), 117; https://doi.org/10.3390/jmse11010117 - 5 Jan 2023
Cited by 22 | Viewed by 7448
Abstract
Following the International Maritime Organization’s goal to reduce greenhouse gas emissions, the interest in the application of wind-assisted ship propulsion (WASP) in maritime transportation is on the rise. Although a variety of WASP systems exist, the application in maritime shipping is still limited, [...] Read more.
Following the International Maritime Organization’s goal to reduce greenhouse gas emissions, the interest in the application of wind-assisted ship propulsion (WASP) in maritime transportation is on the rise. Although a variety of WASP systems exist, the application in maritime shipping is still limited, especially in the case of kite sails. This paper presents a numerical model to carry out a theoretical assessment of the influence of the kite planform area and wind speed on the aerodynamic performance of a kite sail providing propulsive assistance to a 75 m long ship having a Series 60 hull. A static kite sail is assumed, on which a tail wind generates a thrust force to pull the vessel via a tether. While the mass of the kite is neglected, that of the tether is accounted for. A model is implemented for the tensioned tether having a catenary profile. The results generally show a positive correlation between the aerodynamic forces and the kite parameters. As expected, the output parameter values corresponding to the optimal angle of attack for a range of vessel speeds are also found to increase with an increasing relative wind speed. It is concluded that a static 320 m2 kite sail would be sufficient to meet the entire propulsion requirements of the vessel under consideration under appropriate wind conditions. Full article
(This article belongs to the Topic Advances in Wind Energy Technology)
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15 pages, 8651 KB  
Article
Long-Term Observations of Sea Surface Temperature Variability in the Gulf of Mannar
by Sandipan Mondal and Ming-An Lee
J. Mar. Sci. Eng. 2023, 11(1), 102; https://doi.org/10.3390/jmse11010102 - 4 Jan 2023
Cited by 12 | Viewed by 4109
Abstract
In this study, we conducted long-term temporal and spatial observations of monthly, interannual, and decadal sea surface temperature (SST) variation in the Gulf of Mannar (GoM) for the period from 1870 to 2018. We obtained climatological data from the Met Office Hadley Centre, [...] Read more.
In this study, we conducted long-term temporal and spatial observations of monthly, interannual, and decadal sea surface temperature (SST) variation in the Gulf of Mannar (GoM) for the period from 1870 to 2018. We obtained climatological data from the Met Office Hadley Centre, UK. The monthly time series revealed that April and August were the warmest and coolest months of the year, respectively. The mean SSTs for April and August were 29.85 ± 0.44 °C and 27.15 ± 0.49 °C, respectively. The mean annual highest and lowest SSTs were observed in 2015 and 1890 with SSTs of 28.93 ± 0.31 °C and 27.45 ± 0.31 °C, respectively, and the annual time series revealed a warming SST trend of 0.004 °C. Decadal time series also revealed a warming SST trend of 0.04 °C, with the highest and lowest mean decadal SSTs being 28.56 ± 0.21 °C in 2010–2018 and 27.78 ± 0.25 °C in 1890–1889, respectively. Throughout the study period, the spatial distribution of climate trends over decades across the GoM revealed a strong spatial gradient, and the region between 6–8° N and 77–78° E was warmer than all other regions of the GoM. Full article
(This article belongs to the Special Issue Sea Surface Temperature: From Observation to Applications II)
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29 pages, 8177 KB  
Article
The Development and Demonstration of an Enhanced Risk Model for the Evacuation Process of Large Passenger Vessels
by Nikolaos P. Ventikos, Panagiotis Sotiralis, Manolis Annetis, Vasileios C. Podimatas, Evangelos Boulougouris, Fotios Stefanidis, Stefanos Chatzinikolaou and Alessandro Maccari
J. Mar. Sci. Eng. 2023, 11(1), 84; https://doi.org/10.3390/jmse11010084 - 3 Jan 2023
Cited by 17 | Viewed by 4862
Abstract
Evacuating a large and complex environment, such as a large passenger vessel, either cruise or RoPax, is a safety-critical task that involves thousands of people in motion and a complex decision-making process. Despite the significant enhancement of maritime safety over the years, various [...] Read more.
Evacuating a large and complex environment, such as a large passenger vessel, either cruise or RoPax, is a safety-critical task that involves thousands of people in motion and a complex decision-making process. Despite the significant enhancement of maritime safety over the years, various hazards still pose threats to passengers and crew. To deal with this reality, the SafePASS project radically redefines the evacuation process by introducing novel technological solutions. In this context, this paper presents, in detail, an enhanced risk model for the ship evacuation process in order to facilitate the understanding of the actual risks of the process in fire and flooding accidents, and to assess various risk control measures and options toward risk mitigation. The risk model covers the entire event sequence in emergency cases on board, until the survival at sea phase, and it is constructed in two levels, following a combination of event tree analysis and Bayesian networks. Results show the risk corresponds to baseline scenarios for each accident case, which are also verified by relevant IMO and EMSA studies, and an example case of risk control option (RCO) is introduced to the model to demonstrate its ability to assess RCO’s efficiency in terms of risk reduction. Full article
(This article belongs to the Special Issue Risk Assessment and Management in Complex Marine Systems)
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26 pages, 12351 KB  
Article
Alternative Power Options for Improvement of the Environmental Friendliness of Fishing Trawlers
by Marija Koričan, Maja Perčić, Nikola Vladimir, Neven Alujević and Ailong Fan
J. Mar. Sci. Eng. 2022, 10(12), 1882; https://doi.org/10.3390/jmse10121882 - 3 Dec 2022
Cited by 48 | Viewed by 8097
Abstract
The fishing sector is faced with emission problems arising from the extensive use of diesel engines as prime movers. Energy efficiency, environmental performance, and minimization of operative costs through the reduction of fuel consumption are key research topics across the whole maritime sector. [...] Read more.
The fishing sector is faced with emission problems arising from the extensive use of diesel engines as prime movers. Energy efficiency, environmental performance, and minimization of operative costs through the reduction of fuel consumption are key research topics across the whole maritime sector. Ship emissions can be determined at different levels of complexity and accuracy, i.e., by analyzing ship technical data and assuming its operative profile, or by direct measurements of key parameters. This paper deals with the analysis of the environmental footprint of a fishing trawler operating in the Adriatic Sea, including three phases of the Life-Cycle Assessment (manufacturing, Well-to-Pump (WTP), and Pump-to-Wake (PTW)). Based on the data on fuel consumption, the viability of replacing the conventional diesel-powered system with alternative options is analyzed. The results showed that fuels such as LNG and B20 represent the easiest solution that would result in a reduction of harmful gases and have a positive impact on overall costs. Although electrification and hydrogen represent one of the cleanest forms of energy, due to their high price and complex application in an obsolete fleet, they do not present an optimal solution for the time being. The paper showed that the use of alternative fuels would have a positive effect on the reduction of harmful emissions, but further work is needed to find an environmentally acceptable and economically profitable pathway for redesigning the ship power system of fishing trawlers. Full article
(This article belongs to the Special Issue Decarbonization of Ship Power Plants)
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19 pages, 3351 KB  
Article
The Impact of Marine Engine Component Failures upon an Explosion in the Starting Air Manifold
by Leszek Chybowski, Daniel Wiaterek and Andrzej Jakubowski
J. Mar. Sci. Eng. 2022, 10(12), 1850; https://doi.org/10.3390/jmse10121850 - 1 Dec 2022
Cited by 10 | Viewed by 7764
Abstract
Based on available sources, the frequency of explosions in the marine engine’s starting air manifolds is determined under real conditions. A cause-and-effect analysis of these explosions and their root causes are identified. A probabilistic model of an explosion in the starting air manifold [...] Read more.
Based on available sources, the frequency of explosions in the marine engine’s starting air manifolds is determined under real conditions. A cause-and-effect analysis of these explosions and their root causes are identified. A probabilistic model of an explosion in the starting air manifold of a marine engine is built using a fault tree analysis (FTA). Using a stochastic simulation (Monte Carlo) and an exact reliability availability calculation (ERAC) algorithm applied to the developed FTA model, selected reliability measures are calculated to describe an incident of the top event, which involves an explosion in the starting air manifold. For such an event, several factors are calculated, including the availability, the unavailability, the failure frequency, and the mean time to failure. Based on the simulations, the relative frequency of the top event is determined in relation to the number of events that can simultaneously occur and lead to an explosion. The significance of each basic event is assessed to determine their individual impact on the explosion incident. The following measures are used: the Vesely–Fussell measure of importance, the criticality measure of importance, the Birnbaum measure of reliability importance, and the Birnbaum measure of structural importance. The results of the analysis show that defective starting air valves are most responsible for the explosion incident in the starting air manifold. During the first year of the ship’s operation, the reliability does not fall below the value of 0.65, while the mean time to failure and the top event frequency are statistically at the level of one explosion per approximately 2.28 years of continuous engine operation. Full article
(This article belongs to the Special Issue Risk Analysis of Maritime Accidents)
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39 pages, 14922 KB  
Article
Technological Potential Analysis and Vacant Technology Forecasting in Properties and Composition of Low-Sulfur Marine Fuel Oil (VLSFO and ULSFO) Bunkered in Key World Ports
by Mikhail A. Ershov, Vsevolod D. Savelenko, Alisa E. Makhmudova, Ekaterina S. Rekhletskaya, Ulyana A. Makhova, Vladimir M. Kapustin, Daria Y. Mukhina and Tamer M. M. Abdellatief
J. Mar. Sci. Eng. 2022, 10(12), 1828; https://doi.org/10.3390/jmse10121828 - 28 Nov 2022
Cited by 44 | Viewed by 8805
Abstract
Analysis of the very-low-sulfur fuel oil (VLSFO) and ultra-low-sulfur fuel oil (ULSFO) bunkered in key ports in Asia, the Middle East, North America, Western Europe, and Russia is presented. The characteristics of said fuels, including density, sulfur content, kinematic viscosity, aluminum and silicon [...] Read more.
Analysis of the very-low-sulfur fuel oil (VLSFO) and ultra-low-sulfur fuel oil (ULSFO) bunkered in key ports in Asia, the Middle East, North America, Western Europe, and Russia is presented. The characteristics of said fuels, including density, sulfur content, kinematic viscosity, aluminum and silicon content, vanadium and nickel content, as well as pour point are investigated. Furthermore, the main trends and correlations are also discussed. Based on the graphical and mathematical analysis of the properties, the composition of the fuels is predicted. The key fuel components in Asian ports, the most important of which is Singapore, are hydrodesulfurized atmospheric residues (AR) (50–70%) and catalytic cracker heavy cycle oil (HCO) (15–35%) with the addition of other components, which is explained by the presence of a number of large oil refining centers in the area. In the Middle East ports, the most used VLSFO compositions are based on available resources of low-sulfur components, namely hydrodesulfurized AR, the production facilities of which were recently built in the region. In European ports, due to the relatively low sulfur content in processed oils, straight-run AR is widely used as a component of low-sulfur marine fuels. In addition, fuels in Western European ports contain on average significantly more hydrotreated vacuum gas oil (21%) than in the rest of the world (4–5%). Finally, a mixture of hydrotreated (80–90%) and straight-run fuel oil (10–15%) with a sulfur content of no more than 2.0–2.5% is used as the base low-sulfur component of marine fuels in the ports of Singapore and the Middle East. Full article
(This article belongs to the Special Issue Marine Fuels and Green Energy)
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22 pages, 25599 KB  
Article
Coastal Vulnerability Assessment for Future Sea Level Rise and a Comparative Study of Two Pocket Beaches in Seasonal Scale, Ios Island, Cyclades, Greece
by Apostolia Komi, Alexandros Petropoulos, Niki Evelpidou, Serafeim Poulos and Vasilios Kapsimalis
J. Mar. Sci. Eng. 2022, 10(11), 1673; https://doi.org/10.3390/jmse10111673 - 6 Nov 2022
Cited by 19 | Viewed by 4408
Abstract
The coastal zone may be considered as the location where the marine and land environments interact dynamically and coexist with human societies. Globally, natural and human systems are being severely threatened by the sea level rise related to climate change. The outcome between [...] Read more.
The coastal zone may be considered as the location where the marine and land environments interact dynamically and coexist with human societies. Globally, natural and human systems are being severely threatened by the sea level rise related to climate change. The outcome between the dynamic relationship of coastal environments and marine processes, and the future sea level rise as predicted by scientific reports, is the vulnerability of coastal areas such as sandy beaches, pocket beaches and low-lying coastal areas. The current research aims to assess the coastal vulnerability of Ios Island, Cyclades, Greece for the next 100 years and to identify areas that are comparatively more vulnerable to future sea level changes. Moreover, the seasonal changes concerning sedimentological and morphological characteristics of two pocket beaches of Ios Island, Mylopotas and Magganari, are also examined. From the application of the Coastal Vulnerability Index, 92.37% of the total length of the coastline of Ios Island is characterized by a very low vulnerability as it consists of rocky shores and cliffs, while sandy and pocket beaches are characterized by a very high vulnerability. From the fieldworks and data processing, the seasonal changes mainly concern the seabed’s topography, the sediments’ texture of the collected sand samples, the foreshore and backshore topography, as well as seasonal shoreline displacement, using the Digital Shoreline Analysis System tool (DSAS). Full article
(This article belongs to the Special Issue Coastal Systems: Monitoring, Protection and Adaptation Approaches)
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14 pages, 10589 KB  
Article
CFD Study on the Influence of Exostructure Elements on the Resistance of a Submarine
by Inno Gatin, Juvel Čokić, Darjan Romić and Joško Parunov
J. Mar. Sci. Eng. 2022, 10(10), 1542; https://doi.org/10.3390/jmse10101542 - 20 Oct 2022
Cited by 7 | Viewed by 4099
Abstract
Submersible vessels designed to operate at low speeds are often designed with an intricate exostructure, as well as other elements that are located outside of the main pressure hull. Exostructure elements are often of cylindrical or rectangular shape, positioned perpendicularly to the flow [...] Read more.
Submersible vessels designed to operate at low speeds are often designed with an intricate exostructure, as well as other elements that are located outside of the main pressure hull. Exostructure elements are often of cylindrical or rectangular shape, positioned perpendicularly to the flow direction. For this reason, their resistance coefficient is relatively large compared to the pressure hull or appendages of a classical submarine. In some cases, the exostructure can significantly increase the wetted surface of the vessel and dominate its resistance. This paper presents a study on how different exostructure elements impact the overall resistance of a submarine relative to the resistance of the cylindrical, smooth, pressure hull. Additionally, the effect of depth is also considered. The study is conducted using the RANS-based CFD method. The subject of the study is a 25 m long tourist submarine designed for depths up to 40 m and a speed of up to 3 knots. Full article
(This article belongs to the Special Issue Design, Analysis and Maintenance of Green Innovative Marine Structures)
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22 pages, 6110 KB  
Article
Operational Modeling of North Aegean Oil Spills Forced by Real-Time Met-Ocean Forecasts
by Panagiota Keramea, Nikolaos Kokkos, Georgios D. Gikas and Georgios Sylaios
J. Mar. Sci. Eng. 2022, 10(3), 411; https://doi.org/10.3390/jmse10030411 - 12 Mar 2022
Cited by 18 | Viewed by 6224
Abstract
Over the latest decades, oil marine pollution has posed a vital threat for global ocean health, since spillages of any scale are related to environmental, social and financial impacts. The worldwide increase in oil and gas demand, and the parallel rise in oil [...] Read more.
Over the latest decades, oil marine pollution has posed a vital threat for global ocean health, since spillages of any scale are related to environmental, social and financial impacts. The worldwide increase in oil and gas demand, and the parallel rise in oil and gas production, exploiting particularly coastal and offshore marine deposits, have significantly increased the risk of accidental oil release to the sea. In the present study, an operational oil spill model was applied to test the oil dispersive properties and to reveal the relative magnitude of weathering processes, after an accidental oil spill release along the main tanker transportation route in the North Aegean Sea. Numerical simulations were implemented using the OpenOil transport and fate numerical model, a subclass of the OpenDrift open-source trajectory framework. This model integrates algorithms with several physical processes, such as oil entrainment, vertical mixing, oil resurfacing and oil emulsification. The oil dispersion model was coupled to real-time met-ocean forecasts received from NOAA-GFS and CMEMS. Present simulation results have focused on the impact of turbulent kinetic energy, induced by the background flow field, on the horizontal spreading of particles, as well as on the evolution of oil mass balance and oil mass properties. Full article
(This article belongs to the Section Marine Pollution)
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24 pages, 3241 KB  
Article
Hydrodynamics of a Moored Permeable Vertical Cylindrical Body
by Dimitrios N. Konispoliatis, Ioannis K. Chatjigeorgiou and Spyros A. Mavrakos
J. Mar. Sci. Eng. 2022, 10(3), 403; https://doi.org/10.3390/jmse10030403 - 10 Mar 2022
Cited by 2 | Viewed by 4358
Abstract
In this study, the problems of diffraction and radiation of water waves by a permeable vertical cylindrical body are formulated within the realm of the linear potential theory. The body, which is floating in constant water depth, is moored with a catenary mooring [...] Read more.
In this study, the problems of diffraction and radiation of water waves by a permeable vertical cylindrical body are formulated within the realm of the linear potential theory. The body, which is floating in constant water depth, is moored with a catenary mooring line system. The method of matched eigenfunction expansions for the prediction of the velocity potential in the fluid domain surrounding the body is applied. Furthermore, the static and dynamic characteristics of the mooring system are combined with the hydrodynamics of the body, to set up the coupled motion equations of the dynamical model, i.e., floater and mooring system, in the frequency domain. Numerical results obtained through the developed solution are presented. The results revealed that porosity plays a key role in reducing/controlling the exciting wave loads. As far as the mooring system is concerned, its quasi-static and dynamic characteristics, by employing several motion directions on the fairlead in accordance to varying environmental conditions, are examined, highlighting their effect on the body’s motions. Full article
(This article belongs to the Special Issue Hydrodynamics of Fish Cages and Floating Permeable Structures)
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19 pages, 5815 KB  
Article
Tailored Leaching Tests as a Tool for Environmental Management of Mine Tailings Disposal at Sea
by Kristine B. Pedersen, Tore Lejon and Anita Evenset
J. Mar. Sci. Eng. 2022, 10(3), 405; https://doi.org/10.3390/jmse10030405 - 10 Mar 2022
Cited by 4 | Viewed by 4518
Abstract
The expanding human activities in coastal areas increase the need for developing solutions to limit impacts on the marine environment. Sea disposal affects the marine environment, but despite the growing knowledge of potential impacts, there are still no standardized leaching tests for sea [...] Read more.
The expanding human activities in coastal areas increase the need for developing solutions to limit impacts on the marine environment. Sea disposal affects the marine environment, but despite the growing knowledge of potential impacts, there are still no standardized leaching tests for sea disposal. The aim of this study was to contribute to the development of leaching tests, exemplified using mine tailings, planned for submarine disposal in the Repparfjord, Norway. The mine tailings had elevated concentrations of Ba, Cr, Cu, Mn and Ni compared to background concentrations in the Repparfjord. Variables known to affect metal leaching in marine environments (DOC, pH, salinity, temperature, aerated/anoxic) were studied, as was the effect of flocculant (Magnafloc10), planned to be added prior to discharge. Stirred/non-stirred setups simulated the resuspension and disposal phases. Leaching of metals was below 2% in all experiments, with the highest rate observed for Cu and Mn. Multivariate analysis revealed a different variable importance for metals depending on their association with minerals. Higher leaching during resuspension than disposal, and lower leaching with the addition of Magnafloc10, especially for Cu and Mn, was observed. The leaching tests performed in this study are transferable to other materials for sea disposal. Full article
(This article belongs to the Special Issue Sediment Remediation at Harbour)
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25 pages, 7253 KB  
Article
Comparative Assessment and Parametric Optimisation of Large Marine Two-Stroke Engines with Exhaust Gas Recirculation and Alternative Turbocharging Systems
by Daoyi Lu, Gerasimos Theotokatos, Jundong Zhang, Hong Zeng and Keying Cui
J. Mar. Sci. Eng. 2022, 10(3), 351; https://doi.org/10.3390/jmse10030351 - 2 Mar 2022
Cited by 15 | Viewed by 6196
Abstract
Although the exhaust gas recirculation (EGR) technology has been proven effective to decrease the marine engine’s nitrogen oxides (NOx) emissions, it is associated with a considerable fuel consumption increase and challenges to the engine–turbocharger matching. This study aims to parametrically optimise the EGR [...] Read more.
Although the exhaust gas recirculation (EGR) technology has been proven effective to decrease the marine engine’s nitrogen oxides (NOx) emissions, it is associated with a considerable fuel consumption increase and challenges to the engine–turbocharger matching. This study aims to parametrically optimise the EGR and turbocharging system settings of a large marine two-stroke engine with the objective of obtaining the highest engine efficiency whilst ensuring compliance with the prevailing NOx emissions limits. Two typical configurations of the investigated engine (baseline and alternative) are modelled in the GT-SUITE software. Parametric simulations are performed with EGR rates up to 40% along with cylinder bypass rates up to 50%, and the simulation results are analysed to quantify the impact of the engine operation with EGR on the performance and NOx emissions parameters. For the baseline engine configuration, the EGR rate increase considerably deteriorates the brake specific fuel consumption (BSFC), which is attenuated by opening the cylinder bypass valve. The optimal combinations of the EGR and cylinder bypass rates for each operating point are identified for both configurations. Following the comparative assessment between the two engine configurations, recommendations for the engine operating modes are proposed, leading to BSFC improvement in the region of 0.7 to 2.9 g/kWh. This study provides insights for the operational settings optimisation of two-stroke engines equipped with EGR systems, contributing towards the reduction of the associated environmental carbon footprint. Full article
(This article belongs to the Section Ocean Engineering)
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17 pages, 5938 KB  
Article
Automated Tethered Profiler for Hydrophysical and Bio-Optical Measurements in the Black Sea Carbon Observational Site
by Alexander G. Ostrovskii, Mikhail V. Emelianov, Oleg Y. Kochetov, Vyacheslav V. Kremenetskiy, Dmitry A. Shvoev, Sergey V. Volkov, Andrey G. Zatsepin, Nikolai M. Korovchinsky, Vladimir M. Olshanskiy and Alexander V. Olchev
J. Mar. Sci. Eng. 2022, 10(3), 322; https://doi.org/10.3390/jmse10030322 - 25 Feb 2022
Cited by 18 | Viewed by 5230
Abstract
Biogeochemical cycles of carbon transformation throughout the euphotic zone of the sea are controlled by physical processes, e.g., daily thermocline, variation in solar irradiance, thermohaline convection, and intermittent mixing. These processes should be regularly observed with sufficient time resolution at fixed geographical locations. [...] Read more.
Biogeochemical cycles of carbon transformation throughout the euphotic zone of the sea are controlled by physical processes, e.g., daily thermocline, variation in solar irradiance, thermohaline convection, and intermittent mixing. These processes should be regularly observed with sufficient time resolution at fixed geographical locations. This study provides a brief overview of the carbon observational site in the Northeastern Black Sea. The focus is on the design of a new tethered profiler Winchi for the inner continental shelf part of the site. The profiler hull and two outriggers comprise an open trimaran platform that is positively buoyant and tends to maintain a horizontal position in the water. The lower end of the winch wire is secured to the bottom anchor. By unwinding/winding the wire, the profiler ascends/descends while measuring the depth profiles of marine environment parameters ranging from the seafloor to air–sea interface. After surfacing, the profiler determines its location using the Global Positioning System (GPS) and transmits data to (and from) a server on land through the Global System for Mobile Communications (GSM). Initial field tests with the Winchi profiler at the Northeastern Black Sea shelf exhibited promising results. We report these early tests to demonstrate the use of Winchi. Full article
(This article belongs to the Special Issue Technological Oceanography)
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Article
Investigation on a Large-Scale Braceless-TLP Floating Offshore Wind Turbine at Intermediate Water Depth
by Yiming Zhou, Yajun Ren, Wei Shi and Xin Li
J. Mar. Sci. Eng. 2022, 10(2), 302; https://doi.org/10.3390/jmse10020302 - 21 Feb 2022
Cited by 13 | Viewed by 7629
Abstract
Tension leg platform (TLP) is a cost-effective and high-performance support structure for floating offshore wind turbine (FOWT) because of its small responses in heave, pitch, and roll with the constraint of the tendons. China, as the largest market of offshore wind energy, has [...] Read more.
Tension leg platform (TLP) is a cost-effective and high-performance support structure for floating offshore wind turbine (FOWT) because of its small responses in heave, pitch, and roll with the constraint of the tendons. China, as the largest market of offshore wind energy, has shown a demand for developing reliable, viable floating platform support structures, especially aiming at the intermediate water depth. The present paper described a newly proposed 10-MW Braceless-TLP FOWT designed for a moderate water depth of 60 m. The numerical simulations of the FOWT are carried out using the coupled aero-hydro-servo-elastic-mooring calculation tool FAST. The measured wind and wave data of the target site close to the Fujian Province of China were used to evaluate the performance of the FOWT under the 100-, 50-, 5-, and 2-year-return stochastic weather conditions. The natural periods of the platform in surge, sway, heave, pitch, roll, and yaw were found to be within the range recommended by the design standard DNV-RP-0286 Coupled Analysis of Floating Wind Turbines. The largest surge of the water depth ratio among all the load cases was 15%, which was smaller than the admissible ratio of 23%. The tower top displacements remained between −1 m and 1 m, which were at a similar order to those of a 10-MW monopile-supported offshore wind turbine. The six tendons remained tensioned during the simulation, even under the operational and extreme (parked) environmental conditions. The Braceless-TLP FOWT showed an overall satisfying performance in terms of the structural stability and illustrates the feasibility of this type of FOWT at such a moderate water depth. Full article
(This article belongs to the Special Issue Offshore Wind Turbine Foundations)
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