Journal of Marine Science and Engineering

27 pages, 4389 KiB

Open AccessArticle

Application of Machine Learning for Fuel Consumption and Emission Prediction in a Marine Diesel Engine Using Diesel and Waste Cooking Oil

by Tadas Žvirblis, Kristina Čižiūnienė and Jonas Matijošius

J. Mar. Sci. Eng. 2025, 13(7), 1328; https://doi.org/10.3390/jmse13071328 (registering DOI) - 11 Jul 2025

Abstract

This study creates and tests a machine learning model that can predict fuel use and emissions (NO_x, CO₂, CO, HC, PN) from a marine internal combustion engine when it is running normally. The model learned from data collected from [...] Read more.

This study creates and tests a machine learning model that can predict fuel use and emissions (NO_x, CO₂, CO, HC, PN) from a marine internal combustion engine when it is running normally. The model learned from data collected from conventional diesel fuel experiments. Subsequently, we evaluated its ability to transfer by employing the parameters associated with waste cooking oil (WCO) biodiesel and its 60/40 diesel mixture. The machine learning model demonstrated exceptional proficiency in forecasting diesel mode (R² > 0.95), effectively encapsulating both long-term trends and short-term fluctuations in fuel consumption and emissions across various load regimes. Upon the incorporation of WCO data, the model maintained its capacity to identify trends; however, it persistently overestimated emissions of CO, HC, and PN. This discrepancy arose primarily from the differing chemical composition of the fuel, particularly in terms of oxygen content and density. A significant correlation existed between indicators of incomplete combustion and the utilization of fuel. Nonetheless, NO_x exhibited an inverse relationship with indicators of combustion efficiency. The findings indicate that the model possesses the capability to estimate emissions in real time, requiring only a modest amount of additional training to operate effectively with alternative fuels. This approach significantly diminishes the necessity for prolonged experimental endeavors, rendering it an invaluable asset for the formulation of fuel strategies and initiatives aimed at mitigating carbon emissions in maritime operations. Full article

(This article belongs to the Section Ocean Engineering)

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26 pages, 4555 KiB

Open AccessArticle

Influence of Geometric Effects on Dynamic Stall in Darrieus-Type Vertical-Axis Wind Turbines for Offshore Renewable Applications

by Qiang Zhang, Weipao Miao, Kaicheng Zhao, Chun Li, Linsen Chang, Minnan Yue and Zifei Xu

J. Mar. Sci. Eng. 2025, 13(7), 1327; https://doi.org/10.3390/jmse13071327 (registering DOI) - 11 Jul 2025

Abstract

The offshore implementation of vertical-axis wind turbines (VAWTs) presents a promising new paradigm for advancing marine wind energy utilization, owing to their omnidirectional wind acceptance, compact structural design, and potential for lower maintenance costs. However, VAWTs still face major aerodynamic challenges, particularly due [...] Read more.

The offshore implementation of vertical-axis wind turbines (VAWTs) presents a promising new paradigm for advancing marine wind energy utilization, owing to their omnidirectional wind acceptance, compact structural design, and potential for lower maintenance costs. However, VAWTs still face major aerodynamic challenges, particularly due to the pitching motion, where the angle of attack varies cyclically with the blade azimuth. This leads to strong unsteady effects and susceptibility to dynamic stalls, which significantly degrade aerodynamic performance. To address these unresolved issues, this study conducts a comprehensive investigation into the dynamic stall behavior and wake vortex evolution induced by Darrieus-type pitching motion (DPM). Quasi-three-dimensional CFD simulations are performed to explore how variations in blade geometry influence aerodynamic responses under unsteady DPM conditions. To efficiently analyze geometric sensitivity, a surrogate model based on a radial basis function neural network is constructed, enabling fast aerodynamic predictions. Sensitivity analysis identifies the curvature near the maximum thickness and the deflection angle of the trailing edge as the most influential geometric parameters affecting lift and stall behavior, while the blade thickness is shown to strongly impact the moment coefficient. These insights emphasize the pivotal role of blade shape optimization in enhancing aerodynamic performance under inherently unsteady VAWT operating conditions. Full article

(This article belongs to the Special Issue Advanced Studies in Marine Data Analysis)

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22 pages, 3656 KiB

Open AccessArticle

Wetland Ecological Restoration and Geomorphological Evolution: A Hydrodynamic-Sediment-Vegetation Coupled Modeling Study

by Haiyang Yan, Bing Shi and Feng Gao

J. Mar. Sci. Eng. 2025, 13(7), 1326; https://doi.org/10.3390/jmse13071326 (registering DOI) - 10 Jul 2025

Abstract

This study developed a coupled hydrodynamic-sediment-vegetation model to investigate the effects of Spartina alterniflora management and Suaeda salsa restoration on coastal wetland geomorphological evolution and vegetation distribution. Special attention is paid to the regulatory roles of tidal dynamics, sea-level rise, sediment supply, and [...] Read more.

This study developed a coupled hydrodynamic-sediment-vegetation model to investigate the effects of Spartina alterniflora management and Suaeda salsa restoration on coastal wetland geomorphological evolution and vegetation distribution. Special attention is paid to the regulatory roles of tidal dynamics, sea-level rise, sediment supply, and sediment characteristics. The study shows that the management of Spartina alterniflora significantly alters the sediment deposition patterns in salt marsh wetlands, leading to intensified local erosion and a decline in the overall stability of the wetland system; meanwhile, the geomorphology of wetlands restored with Suaeda salsa is influenced by tidal range, sediment settling velocity, and suspended sediment concentration, exhibiting different deposition and erosion patterns. Under the scenario of sea-level rise, when sedimentation rates fail to offset the rate of sea-level increase, the wetland ecosystem faces the risk of collapse. This study provides scientific evidence for the ecological restoration and management of coastal wetlands and offers theoretical support for future wetland conservation and restoration policies. Full article

(This article belongs to the Section Coastal Engineering)

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23 pages, 8011 KiB

Open AccessArticle

Efficient Prediction of Shallow-Water Acoustic Transmission Loss Using a Hybrid Variational Autoencoder–Flow Framework

by Bolin Su, Haozhong Wang, Xingyu Zhu, Penghua Song and Xiaolei Li

J. Mar. Sci. Eng. 2025, 13(7), 1325; https://doi.org/10.3390/jmse13071325 (registering DOI) - 10 Jul 2025

Abstract

Efficient prediction of shallow-water acoustic transmission loss (TL) is crucial for underwater detection, recognition, and communication systems. Traditional physical modeling methods require repeated calculations for each new scenario in practical waveguide environments, leading to low computational efficiency. Deep learning approaches, based on data-driven [...] Read more.

Efficient prediction of shallow-water acoustic transmission loss (TL) is crucial for underwater detection, recognition, and communication systems. Traditional physical modeling methods require repeated calculations for each new scenario in practical waveguide environments, leading to low computational efficiency. Deep learning approaches, based on data-driven principles, enable accurate input–output approximation and batch processing of large-scale datasets, significantly reducing computation time and cost. To establish a rapid prediction model mapping sound speed profiles (SSPs) to acoustic TL through controllable generation, this study proposes a hybrid framework that integrates a variational autoencoder (VAE) and a normalizing flow (Flow) through a two-stage training strategy. The VAE network is employed to learn latent representations of TL data on a low-dimensional manifold, while the Flow network is additionally used to establish a bijective mapping between the latent variables and underwater physical parameters, thereby enhancing the controllability of the generation process. Combining the trained normalizing flow with the VAE decoder could establish an end-to-end mapping from SSPs to TL. The results demonstrated that the VAE–Flow network achieved higher computational efficiency, with a computation time of 4 s for generating 1000 acoustic TL samples, versus the over 500 s required by the KRAKEN model, while preserving accuracy, with median structural similarity index measure (SSIM) values over 0.90. Full article

(This article belongs to the Special Issue Data-Driven Methods for Marine Structures)

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31 pages, 878 KiB

Open AccessArticle

Berth Efficiency Under Risk Conditions in Seaports Through Integrated DEA and AHP Analysis

by Deda Đelović, Marinko Aleksić, Oto Iker and Michail Chalaris

J. Mar. Sci. Eng. 2025, 13(7), 1324; https://doi.org/10.3390/jmse13071324 (registering DOI) - 10 Jul 2025

Abstract

In the context of increasingly complex and dynamic maritime logistics, seaports serve as critical nodes for intermodal transport, energy distribution, and global trade. Ensuring the safe and uninterrupted operation of port infrastructure—particularly berths—is vital for maintaining supply chain resilience. This study explores the [...] Read more.

In the context of increasingly complex and dynamic maritime logistics, seaports serve as critical nodes for intermodal transport, energy distribution, and global trade. Ensuring the safe and uninterrupted operation of port infrastructure—particularly berths—is vital for maintaining supply chain resilience. This study explores the impact of multiple risk categories on berth efficiency in a seaport, aligning with the growing emphasis on maritime safety and risk-informed decision-making. A two-stage methodology is adopted. In the first phase, the DEA CCR input-oriented model is employed to assess the efficiency of selected berths considered as Decision Making Units (DMUs). In the second phase, the Analytical Hierarchy Process (AHP) is used to categorize and quantify the impact of four major risk classes—operational, technical, safety, and environmental—on berth efficiency. The results demonstrate that operational and safety risks contribute 63.91% of the composite weight in the AHP risk assessment hierarchy. These findings are highly relevant to contemporary efforts in maritime risk modeling, especially for individual ports and port systems with high berth utilization and vulnerability to system disruptions. The proposed integrated approach offers a scalable and replicable decision-support tool for port authorities, port operators, planners, and maritime safety stakeholders, enabling proactive risk mitigation, optimal utilization of available resources in a port, and improved berth performance. Its methodological design is appropriately suited to support further applications in port resilience frameworks and maritime safety strategies, being one of the bases for establishing collision avoidance strategies related to an individual port and/or port system, too. Full article

(This article belongs to the Special Issue Recent Advances in Maritime Safety and Ship Collision Avoidance)

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24 pages, 5219 KiB

Open AccessArticle

Experimental Study on Mechanical Integrity of Cement and EICP-Solidified Soil for Scour Protection of Pile Foundations

by Feng Cao, Qilin Zhang, Wei Qin, Haoran Ouyang, Zhiyue Li, Yutao Peng and Guoliang Dai

J. Mar. Sci. Eng. 2025, 13(7), 1323; https://doi.org/10.3390/jmse13071323 (registering DOI) - 10 Jul 2025

Abstract

Among the scour protection measures for pile foundations, the use of solidified mud has demonstrated effective protection against scour. However, research on the mechanical integrity of this protective measure is relatively scarce. Therefore, a series of experiments were performed on cement-solidified soil and [...] Read more.

Among the scour protection measures for pile foundations, the use of solidified mud has demonstrated effective protection against scour. However, research on the mechanical integrity of this protective measure is relatively scarce. Therefore, a series of experiments were performed on cement-solidified soil and Enzyme-Induced Carbonate Precipitation (ECIP) solidified soil to analyze fluidity, disintegration, and unconfined compressive strength, along with an analysis of influencing parameters. Test results show the following: for cement-solidified soil, fluidity decreases with higher cement content, while its disintegration rate decreases with more cement and its unconfined compressive strength increases with a longer curing time and higher cement content. For ECIP-solidified soil, fluidity decreases with higher soy powder concentration but increases with higher binder solution concentration. ECIP’s initial disintegration rate increases with binder concentration, but after 7 days curing, its disintegration rate decreases with both higher binder concentration and higher soy powder concentration. ECIP’s strength increases with higher soy powder concentration. Crucially, both types of solidified soil exhibit decreased unconfined compressive strength with higher initial water content. The research results can provide a reference for the construction of solidified soil in the field of scour protection. Full article

(This article belongs to the Section Ocean Engineering)

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16 pages, 2292 KiB

Open AccessArticle

Passive Synthetic Aperture for Direction-of-Arrival Estimation Using an Underwater Glider with a Single Hydrophone

by Yueming Ma, Jie Sun, Shuo Li, Tianze Hu, Shilong Li and Yuexing Zhang

J. Mar. Sci. Eng. 2025, 13(7), 1322; https://doi.org/10.3390/jmse13071322 - 10 Jul 2025

Abstract

This paper addresses the aperture limitation problem faced by array-equipped underwater gliders (UGs) in direction-of-arrival (DOA) estimation. A passive synthetic aperture (PSA) method for DOA estimation using a single hydrophone mounted on a UG is proposed. This method uses the motion of the [...] Read more.

This paper addresses the aperture limitation problem faced by array-equipped underwater gliders (UGs) in direction-of-arrival (DOA) estimation. A passive synthetic aperture (PSA) method for DOA estimation using a single hydrophone mounted on a UG is proposed. This method uses the motion of the UG to synthesize a linear array whose elements are positioned to acquire the target signal, thereby increasing the array aperture. The dead-reckoning method is used to determine the underwater trajectory of the UG, and the UG’s trajectory was corrected by the UG motion parameters, from which the array shape was adjusted accordingly and the position of the array elements was corrected. Additionally, array distortion caused by movement offsets due to ocean currents underwent linearization, reducing computational complexity. To validate the proposed method, a sea trial was conducted in the South China Sea using the Haiyi 1000 UG equipped with a hydrophone, and its effectiveness was demonstrated through the processing of the collected data. The performance of DOA estimation prior to and following UG trajectory correction was compared to evaluate the impact of ocean currents on target DOA estimation accuracy. Full article

(This article belongs to the Topic Advances in Underwater Signal Processing and Communication: Challenges, Innovations, and Applications)

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23 pages, 6990 KiB

Open AccessArticle

Fault Signal Emulation of Marine Turbo-Rotating Systems Based on Rotor-Gear Dynamic Interaction Modeling

by Seong Hyeon Kim, Hyun Min Song, Se Hyeon Jeong, Won Joon Lee and Sun Je Kim

J. Mar. Sci. Eng. 2025, 13(7), 1321; https://doi.org/10.3390/jmse13071321 - 9 Jul 2025

Abstract

Rotating machinery is essential in various industrial fields, and growing demands for high performance under harsh operating conditions have heightened interest in fault diagnosis and prognostic technologies. However, a major challenge in fault diagnosis research lies in the scarcity of data, primarily due [...] Read more.

Rotating machinery is essential in various industrial fields, and growing demands for high performance under harsh operating conditions have heightened interest in fault diagnosis and prognostic technologies. However, a major challenge in fault diagnosis research lies in the scarcity of data, primarily due to the inability to deliberately introduce faults into machines during actual operation. In this study, a physical model is proposed to realistically simulate the system behavior of a ship’s turbo-rotating machinery by coupling the torsional and lateral vibrations of the rotor. While previous studies employed simplified single-shaft models, the proposed model adopted gear mesh interactions to reflect the coupling behavior between shafts. Furthermore, the time-domain response of the system is analyzed through state-space transformation. The proposed model was applied to simulate imbalance and gear teeth damage conditions that may occur in marine turbo-rotating systems and the results were compared with those under normal operating conditions. The analysis confirmed that the model effectively reproduces fault-induced dynamic characteristics. By enabling rapid implementation of various fault conditions and efficient data acquisition data, the proposed model is expected to contribute to enhancing the reliability of fault diagnosis and prognostic research. Full article

(This article belongs to the Section Ocean Engineering)

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32 pages, 15347 KiB

Open AccessArticle

Research on Optimization Design of Ice-Class Ship Form Based on Actual Sea Conditions

by Yu Lu, Xuan Cao, Jiafeng Wu, Xiaoxuan Peng, Lin An and Shizhe Liu

J. Mar. Sci. Eng. 2025, 13(7), 1320; https://doi.org/10.3390/jmse13071320 - 9 Jul 2025

Abstract

With the natural evolution of the Arctic route and advancements in related technologies, the development of new green ice-class ships is becoming a key technological breakthrough for the global shipbuilding industry. As a special vessel form that must perform icebreaking operations and undertake [...] Read more.

With the natural evolution of the Arctic route and advancements in related technologies, the development of new green ice-class ships is becoming a key technological breakthrough for the global shipbuilding industry. As a special vessel form that must perform icebreaking operations and undertake long-distance ocean voyages, an ice-class ship requires sufficient icebreaking capacity to navigate ice-covered water areas. However, since such ships operate for most of their time under open water conditions, it is also crucial to consider their resistance characteristics in these environments. Firstly, this paper employs linear interpolation to extract wind, wave, and sea ice data along the route and calculates the proportion of ice-covered and open water area in the overall voyage. This provides data support for hull form optimization based on real sea state conditions. Then, a resistance optimization platform for ice-class ships is established by integrating hull surface mixed deformation control within a scenario analysis framework. Based on the optimization results, comparative analysis is conducted between the parent hull and the optimized hull under various environmental resistance scenarios. Finally, the optimization results are evaluated in terms of energy consumption using a fuel consumption model of the ship’s main engine. The optimized hull achieves a 16.921% reduction in total resistance, with calm water resistance and wave-added resistance reduced by 5.92% and 27.6%, respectively. Additionally, the optimized hull shows significant resistance reductions under multiple wave and floating ice conditions. At the design speed, calm water power and hourly fuel consumption are reduced by 7.1% and 7.02%, respectively. The experimental results show that the hull form optimization process in this paper can take into account both ice-region navigation and ice-free navigation. The design ideas and solution methods can provide a reference for the design of ice-class ships. Full article

(This article belongs to the Special Issue Navigation Performance and Experimental Research of Ships in Ice-Covered Areas)

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25 pages, 5591 KiB

Open AccessArticle

Towards a Comprehensive Hydrodynamic Model for the Feasibility Study of Motor Yachts

by Francesco Mauro, Ermina Begovic, Enrico Della Valentina, Antonino Dell’Acqua, Barbara Rinauro, Gennaro Rosano and Roberto Tonelli

J. Mar. Sci. Eng. 2025, 13(7), 1319; https://doi.org/10.3390/jmse13071319 (registering DOI) - 9 Jul 2025

Abstract

The design process for motor yachts primarily relies on the experience of designers, who draw upon their knowledge gained from working on similar hull forms. However, when a new concept is to be developed, the experience garnered from standard platforms may not suffice [...] Read more.

The design process for motor yachts primarily relies on the experience of designers, who draw upon their knowledge gained from working on similar hull forms. However, when a new concept is to be developed, the experience garnered from standard platforms may not suffice for achieving a successful design within a short timeframe. Designing a motor yacht involves considering multiple aspects of ship hydrodynamics, including resistance, propulsion, seakeeping, and maneuverability. While these factors have been extensively discussed for different types of ships, a comprehensive joint investigation of hulls, such as those of motor yachts, is noticeably absent in the available literature. This paper aims to fill that gap by providing guidelines for the design of motor yachts with lengths ranging from 20 to 40 m. As part of a preliminary study, a series of 15 yacht hulls were developed, starting from a reference hull form. The resistance, seakeeping and maneuverability performance of these hulls were assessed under specified environmental conditions and speeds, following the ISO 22834:2022 guidelines for comfort assessment. The calculations produced response surfaces detailing the hydrodynamic properties for this series of yachts as functions of the main dimensions of the hulls. Ultimately, these responses assist in identifying optimal design solutions for the main dimensions of a new motor yacht within the 20 to 40 m length range. Full article

(This article belongs to the Section Ocean Engineering)

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38 pages, 4650 KiB

Open AccessReview

Overview of Path Planning and Motion Control Methods for Port Transfer Vehicles

by Mei Yang, Dan Zhang and Haonan Wang

J. Mar. Sci. Eng. 2025, 13(7), 1318; https://doi.org/10.3390/jmse13071318 - 9 Jul 2025

Abstract

Recent advancements have been made in unmanned freight systems at ports, effectively improving port freight efficiency and being widely promoted and popularized in the field of cargo transportation in major ports around the world. The path planning and motion control of port transfer [...] Read more.

Recent advancements have been made in unmanned freight systems at ports, effectively improving port freight efficiency and being widely promoted and popularized in the field of cargo transportation in major ports around the world. The path planning and motion control of port transfer vehicles are the key technology for automatic transportation of vehicles. How to integrate cutting-edge unmanned driving control technology into port unmanned freight transportation and improve the level of port automation is currently an important issue. This article introduces the three-layer control operation architecture of unmanned freight systems in ports, as well as the challenges of applying path planning and motion control technology for unmanned freight vehicles in port environments. It focuses on the mainstream algorithms of path planning and motion control technology, introduces their principles, provides a summary of their current development situation, and elaborates on the improvement and integration achievements of current researchers on algorithms. The algorithms are reviewed and contrasted, highlighting their respective strengths and weaknesses. Finally, this article looks ahead to the development trend of unmanned cargo transportation in ports and provides reference for the automation and intelligent upgrading of unmanned cargo transportation in ports in the future. Full article

(This article belongs to the Section Ocean Engineering)

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21 pages, 3801 KiB

Open AccessArticle

Influence of Snow Redistribution and Melt Pond Schemes on Simulated Sea Ice Thickness During the MOSAiC Expedition

by Jiawei Zhao, Yang Lu, Haibo Zhao, Xiaochun Wang and Jiping Liu

J. Mar. Sci. Eng. 2025, 13(7), 1317; https://doi.org/10.3390/jmse13071317 - 9 Jul 2025

Abstract

The observations of atmospheric, oceanic, and sea ice data from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition were used to analyze the influence of snow redistribution and melt-pond processes on the evolution of sea ice thickness (SIT) in [...] Read more.

The observations of atmospheric, oceanic, and sea ice data from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition were used to analyze the influence of snow redistribution and melt-pond processes on the evolution of sea ice thickness (SIT) in 2019 and 2020. To mitigate the effect of missing atmospheric observations from the time of the expedition, we used ERA5 atmospheric reanalysis along the MOSAiC drift trajectory to force the single-column sea ice model Icepack. SIT simulations from six combinations of two melt-pond schemes and three snow-redistribution configurations of Icepack were compared with observations and analyzed to investigate the sources of model–observation discrepancies. The three snow-redistribution configurations are the bulk scheme, the snwITDrdg scheme, and one simulation conducted without snow redistribution. The bulk scheme describes snow loss from level ice to leads and open water, and snwITDrdg describes wind-driven snow redistribution and compaction. The two melt-pond schemes are the TOPO scheme and the LVL scheme, which differ in the distribution of melt water. The results show that Icepack without snow redistribution simulates excessive snow–ice formation, resulting in an SIT thicker than that observed in spring. Applying snow-redistribution schemes in Icepack reduces snow–ice formation while enhancing the congelation rate. The bulk snow-redistribution scheme improves the SIT simulation for winter and spring, while the bias is large in simulations using the snwITDrdg scheme. During the summer, Icepack underestimates the sea ice surface albedo, resulting in an underestimation of SIT at the end of simulation. The simulations using the TOPO scheme are characterized by a more realistic melt-pond evolution compared to those using the LVL scheme, resulting in a smaller bias in SIT simulation. Full article

(This article belongs to the Special Issue Recent Research on the Measurement and Modeling of Sea Ice)

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22 pages, 1773 KiB

Open AccessArticle

Parasites and Microplastics in the Gastrointestinal Tract of Alosa immaculata from the Black Sea—Implications for Health and Condition

by Aurelia Țoțoiu, Elena Stoica, Andreea-Mădălina Ciucă, George-Emanuel Harcotă, Victor Niță and Neculai Patriche

J. Mar. Sci. Eng. 2025, 13(7), 1316; https://doi.org/10.3390/jmse13071316 - 9 Jul 2025

Abstract

Alosa immaculata Bennett, 1835, commonly referred to as the Danube shad, is an anadromous pelagic species of the Clupeidae family, and plays a significant economic role for countries bordering the Black Sea. This study investigates the occurrence of both parasites and microplastics in [...] Read more.

Alosa immaculata Bennett, 1835, commonly referred to as the Danube shad, is an anadromous pelagic species of the Clupeidae family, and plays a significant economic role for countries bordering the Black Sea. This study investigates the occurrence of both parasites and microplastics in A. immaculata specimens collected from Sfântu Georghe, with the aim of assessing their potential impact on fish health. The overall physiological condition of the fish was evaluated using Fulton’s condition factor (K) to determine whether the presence of parasites or microplastics had any measurable effect. Five parasitic genera were identified, including one ectoparasitic species from the genus Mazocraes, and four endoparasitic species from the genera Pronoprymna, Lecithaster, Hysterotylacium, and Contracaecum. Microplastic analysis showed a dominance of particles measuring 1–5 mm (62.5%), with fibers and foils being the only morphological forms detected. The most common colors were black (45%), transparent (35%), blue (12.5%), and brown (7.5%). The distribution of microplastics was higher in the stomach than intestines. Our findings offer critical insights into the combined effects of parasitic infection and microplastic pollution on this key Black Sea species. The integrated methodology, combining parasite load, microplastic content, and condition factor analysis, marks a novel approach in fish health assessment. Full article

(This article belongs to the Section Marine Environmental Science)

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27 pages, 9584 KiB

Open AccessArticle

Dynamic Response of a Floating Dual Vertical-Axis Tidal Turbine System with Taut and Catenary Mooring Under Extreme Environmental Conditions in Non-Operating Mode

by Yunjun Lee, Jinsoon Park and Woo Chul Chung

J. Mar. Sci. Eng. 2025, 13(7), 1315; https://doi.org/10.3390/jmse13071315 - 8 Jul 2025

Abstract

This study analyzes the dynamic response of a floating dual vertical-axis tidal turbine platform under extreme environmental loads, focusing on two different mooring systems as follows: taut and catenary. The analysis assumes a non-operational turbine state where power generation is stopped, and the [...] Read more.

This study analyzes the dynamic response of a floating dual vertical-axis tidal turbine platform under extreme environmental loads, focusing on two different mooring systems as follows: taut and catenary. The analysis assumes a non-operational turbine state where power generation is stopped, and the vertical turbines are lifted for structural protection. Using time-domain simulations via OrcaFlex 11.4, the floating platform’s motion and mooring line effective tensions are evaluated under high waves, strong wind, and current loads. The results reveal that sway and heave motions are significantly influenced by wave excitation, with the catenary system exhibiting larger responses due to mooring system features, while the taut system experiences higher mooring effective tension but shows more restrained motion. Notably, in the roll direction, both systems exhibit peak frequencies unrelated to the wave spectrum, attributed instead to resonance with the system’s natural frequencies—0.12438 Hz for taut and 0.07332 Hz for catenary. Additionally, the failure scenario of ML02 (Mooring Line 02) and the application of dynamic power cables to the floating platform are analyzed. The results demonstrate that under non-operational and extreme load conditions, mooring system type plays a main role in determining platform stability and structural safety. This comparative analysis offers valuable insights for selecting and designing mooring configurations optimized for reliability in extreme environmental conditions. Full article

(This article belongs to the Special Issue Numerical Analysis and Modeling of Floating Structures)

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25 pages, 5336 KiB

Open AccessArticle

A Modified Body Force Model for a Submerged Waterjet

by Dakui Feng, Yongyan Ma, Zichao Cai, Pengwei Yang and Yanlin Zou

J. Mar. Sci. Eng. 2025, 13(7), 1314; https://doi.org/10.3390/jmse13071314 - 8 Jul 2025

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Abstract

The submerged waterjet exhibits advantages such as uniform inflow, minimal flow distortion, and excellent acoustic performance, making it particularly suitable for high-speed vessels. This study investigates the open-water characteristics of the submerged waterjet and develops a body force model for the submerged waterjet [...] Read more.

The submerged waterjet exhibits advantages such as uniform inflow, minimal flow distortion, and excellent acoustic performance, making it particularly suitable for high-speed vessels. This study investigates the open-water characteristics of the submerged waterjet and develops a body force model for the submerged waterjet propulsion system. First, under uniform inflow conditions, numerical simulations were performed using the body force method by replacing the rotor with a virtual blade and simultaneously replacing both the rotor and stator. The results of the body force model were then compared in detail with those obtained using the sliding mesh method. Second, the influence of the inflow velocity plane position on the results of the body force model was analyzed. The results indicate that the body force method, which replaces both the rotor and stator with a virtual blade, fails to accurately simulate the forces acting on various components of the propeller and the true distribution of the propeller’s flow field. In contrast, the method that replaces only the rotor with a virtual blade produces results for component forces and flow fields that are largely consistent with the results of the sliding mesh method, demonstrating the stability and reliability of the body force model. Additionally, the position of the inflow velocity plane has no significant effect on the model’s computational results. Full article

(This article belongs to the Special Issue Novelties in Marine Propulsion)

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31 pages, 2143 KiB

Open AccessArticle

Alternative Fuels in the Maritime Industry: Emissions Evaluation of Bulk Carrier Ships

by Diego Díaz-Cuenca, Antonio Villalba-Herreros, Teresa J. Leo and Rafael d’Amore-Domenech

J. Mar. Sci. Eng. 2025, 13(7), 1313; https://doi.org/10.3390/jmse13071313 - 8 Jul 2025

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Abstract

The maritime industry remains a significant contributor to global greenhouse gas (GHG) emissions. In this article, a systematic study has been performed on the alternative fuel emissions of large cargo ships under different route scenarios and propulsion systems. For this purpose, a set [...] Read more.

The maritime industry remains a significant contributor to global greenhouse gas (GHG) emissions. In this article, a systematic study has been performed on the alternative fuel emissions of large cargo ships under different route scenarios and propulsion systems. For this purpose, a set of key performance indicators (KPIs) are evaluated, including total equivalent CO₂ emissions (CO_2eq), CO_2eq emissions per unit of transport mass and CO_2eq emissions per unit of transport mass per distance. The emissions analysis demonstrates that Liquified Natural Gas (LNG) paired with Marine Gas Oil (MGO) emerges as the most viable short-term solution in comparison with the conventional fuel oil propulsion. Synthetic methanol (eMeOH) paired with synthetic diesel (eDiesel) is identified as the most promising long-term fuel combination. When comparing the European Union (EU) emission calculation system (FuelEU) with the International Maritime Organization (IMO) emission metrics, a discrepancy in emissions reduction outcomes has been observed. The IMO approach appears to favor methanol (MeOH) and liquefied natural gas (LNG) over conventional fuel oil. This is attributed to the fact that the IMO metrics do not consider unburned methane emissions (methane slip) and emissions in the production of fuels (Well-to-Tank). Full article

(This article belongs to the Special Issue Advancing Marine Sustainability: Alternative Fuels and Decarbonizing Technologies for a Low-Carbon Future)

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21 pages, 2223 KiB

Open AccessArticle

Optimized Deployment of Generalized OCDM in Deep-Sea Shadow-Zone Underwater Acoustic Channels

by Haodong Yu, Cheng Chi, Yongxing Fan, Zhanqing Pu, Wei Wang, Li Yin, Yu Li and Haining Huang

J. Mar. Sci. Eng. 2025, 13(7), 1312; https://doi.org/10.3390/jmse13071312 - 8 Jul 2025

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Abstract

Communication in deep-sea shadow zones remains a significant challenge due to high propagation losses, complex multipath effects, long transmission delays, and strong environmental influences. In recent years, orthogonal chirp division multiplexing (OCDM) has demonstrated promising performance in underwater acoustic communication due to its [...] Read more.

Communication in deep-sea shadow zones remains a significant challenge due to high propagation losses, complex multipath effects, long transmission delays, and strong environmental influences. In recent years, orthogonal chirp division multiplexing (OCDM) has demonstrated promising performance in underwater acoustic communication due to its robustness against multipath interference. However, its high peak-to-average power ratio (PAPR) limits its reliability and efficiency in deep-sea shadow-zone environments. This study applies a recently proposed generalized orthogonal chirp division multiplexing (GOCDM) modulation scheme to deep-sea shadow-zone communication. GOCDM follows the same principles as orthogonal signal division multiplexing (OSDM) while offering the advantage of a reduced PAPR. By segmenting the data signal into multiple vector blocks, GOCDM enables flexible resource allocation, optimizing the PAPR without compromising performance. Theoretical analysis and practical simulations confirm that GOCDM preserves the full frequency diversity benefits of traditional OCDM, while mitigating PARR-related limitations. Additionally, deep-sea experiments were carried out to evaluate the practical performance of GOCDM in shadow-zone environments. The experimental results demonstrate that GOCDM achieves superior performance under low signal-to-noise ratio (SNR) conditions, where the system attains a 0 bit error rate (BER) at 4.2 dB and 6.8 dB, making it a promising solution for enhancing underwater acoustic communication in challenging deep-sea environments. Full article

(This article belongs to the Section Ocean Engineering)

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33 pages, 3352 KiB

Open AccessArticle

Optimization Strategy for Underwater Target Recognition Based on Multi-Domain Feature Fusion and Deep Learning

by Yanyang Lu, Lichao Ding, Ming Chen, Danping Shi, Guohao Xie, Yuxin Zhang, Hongyan Jiang and Zhe Chen

J. Mar. Sci. Eng. 2025, 13(7), 1311; https://doi.org/10.3390/jmse13071311 - 7 Jul 2025

Viewed by 187

Abstract

Underwater sonar target recognition is crucial in fields such as national defense, navigation, and environmental monitoring. However, it faces issues such as the complex characteristics of ship-radiated noise, imbalanced data distribution, non-stationarity, and bottlenecks of existing technologies. This paper proposes the MultiFuseNet-AID network, [...] Read more.

Underwater sonar target recognition is crucial in fields such as national defense, navigation, and environmental monitoring. However, it faces issues such as the complex characteristics of ship-radiated noise, imbalanced data distribution, non-stationarity, and bottlenecks of existing technologies. This paper proposes the MultiFuseNet-AID network, aiming to address these challenges. The network includes the TriFusion block module, the novel lightweight attention residual network (NLARN), the long- and short-term attention (LSTA) module, and the Mamba module. Through the TriFusion block module, the original, differential, and cumulative signals are processed in parallel, and features such as MFCC, CQT, and Fbank are fused to achieve deep multi-domain feature fusion, thereby enhancing the signal representation ability. The NLARN was optimized based on the ResNet architecture, with the SE attention mechanism embedded. Combined with the long- and short-term attention (LSTA) and the Mamba module, it could capture long-sequence dependencies with an O(N) complexity, completing the optimization of lightweight long sequence modeling. At the same time, with the help of feature fusion, and layer normalization and residual connections of the Mamba module, the adaptability of the model in complex scenarios with imbalanced data and strong noise was enhanced. On the DeepShip and ShipsEar datasets, the recognition rates of this model reached 98.39% and 99.77%, respectively. The number of parameters and the number of floating point operations were significantly lower than those of classical models, and it showed good stability and generalization ability under different sample label ratios. The research shows that the MultiFuseNet-AID network effectively broke through the bottlenecks of existing technologies. However, there is still room for improvement in terms of adaptability to extreme underwater environments, training efficiency, and adaptability to ultra-small devices. It provides a new direction for the development of underwater sonar target recognition technology. Full article

(This article belongs to the Section Ocean Engineering)

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32 pages, 2907 KiB

Open AccessReview

A Review of Experimental and Numerical Research on the Slamming Problem of High-Performance Vessels

by Yifang Sun, Dapeng Zhang, Zongduo Wu and Yiquan Yu

J. Mar. Sci. Eng. 2025, 13(7), 1310; https://doi.org/10.3390/jmse13071310 - 6 Jul 2025

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Abstract

Slamming load is characterized by a high peak and short duration. Severe slamming phenomena are extremely detrimental to the navigation safety of high-speed vessels, thereby constraining the development and application of high-performance ships. Studies on slamming mechanisms, load distribution, prediction, and mitigation methods [...] Read more.

Slamming load is characterized by a high peak and short duration. Severe slamming phenomena are extremely detrimental to the navigation safety of high-speed vessels, thereby constraining the development and application of high-performance ships. Studies on slamming mechanisms, load distribution, prediction, and mitigation methods are particularly essential. This paper provides a comprehensive review of the theoretical, numerical, and experimental research progress on water-entry slamming for high-performance ships. First, the theoretical foundations and numerical simulation methods of slamming are elaborated. Then, existing research findings are summarized from two perspectives: segmented water entry and full-scale wave loads. Finally, unresolved issues and future research directions are identified. The aim is to offer valuable insights for further advancements in high-performance ship slamming studies. Full article

(This article belongs to the Special Issue Structural Modelling, Safety Assessment, and Advanced Material Application of Marine Structures)

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20 pages, 13331 KiB

Open AccessArticle

Numerical Simulation of Seabed Response Around Monopile Under Wave–Vibration

by Hongyi Du, Dunge Wang, Jiankang Hou, Ziqin Yu, Ze Liu and Yongzhou Cheng

J. Mar. Sci. Eng. 2025, 13(7), 1309; https://doi.org/10.3390/jmse13071309 - 6 Jul 2025

Viewed by 156

Abstract

Monopile foundation is an important foundation form for offshore wind turbines, and the stability of the seabed around it is affected by the combined effects of wave and pile vibration. Based on the Biot consolidation theory and elastoplastic constitutive model, a multi-physical field [...] Read more.

Monopile foundation is an important foundation form for offshore wind turbines, and the stability of the seabed around it is affected by the combined effects of wave and pile vibration. Based on the Biot consolidation theory and elastoplastic constitutive model, a multi-physical field coupling model of wave–vibration–seabed–monopile is constructed, and the dynamic characteristics of seabed pore pressure around the monopile under the joint action of wave–vibration are systematically investigated, and the influences of waves, vibrations, and seabed parameters on the distribution of pore pressure amplitude are analysed in depth. The results show that the increase in wave incident energy will increase the seabed wave pressure, and the suction and pressure generated by pile vibration will change the soil force state; the coupling of waves and vibrations results in pile displacement difference, causing the seabed pore pressure dissipation depth dissimilarity, and the peak relative amplitude of pore pressure and the peak of vibration displacement are in a linear relationship; the wave parameters and seabed characteristics have a significant effect on the change in pore pressure amplitude distribution. Full article

(This article belongs to the Section Ocean Engineering)

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16 pages, 3646 KiB

Open AccessArticle

A Multicriteria Evaluation of Single Underwater Image Improvement Algorithms

by Iracema del P. Angulo-Fernández, Javier Bello-Pineda, J. Alejandro Vásquez-Santacruz, Rogelio de J. Portillo-Vélez, Pedro J. García-Ramírez and Luis F. Marín-Urías

J. Mar. Sci. Eng. 2025, 13(7), 1308; https://doi.org/10.3390/jmse13071308 - 6 Jul 2025

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Abstract

Enhancement and restoration algorithms are widely used in the exploration of coral reefs for improving underwater images. However, by selecting an improvement algorithm based on image quality metrics, image processing key factors such as the execution time are not considered. In response to [...] Read more.

Enhancement and restoration algorithms are widely used in the exploration of coral reefs for improving underwater images. However, by selecting an improvement algorithm based on image quality metrics, image processing key factors such as the execution time are not considered. In response to this issue, herein is presented a novel method built on multicriteria decision analysis that evaluates the processing time and feature point increase with respect to the original image. To set the Decision Matrix (DM), both the processing time and keypoint increase criteria of the evaluated algorithms are normalized. The criteria weights in the DM are set in accordance with the application, and the quantitative metric used to select the best alternative is the highest Weighted Sum Method (WsuM) score. In this work, the DM of six scenarios is shown, since the setting of weights could completely change the decision. For this research’s target application of generating underwater photomosaics, the Dark Channel Prior (DCP) algorithm emerged as the most suitable under a weighting scheme of 75% for processing time and 25% for keypoint increase. This proposal represents a solution for evaluating improvement algorithms in applications where computational efficiency is critical. Full article

(This article belongs to the Section Ocean Engineering)

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19 pages, 3235 KiB

Open AccessArticle

Characteristics and Evaluation of Living Shorelines: A Case Study from Fujian, China

by Xingfan Li, Shihui Lin, Libing Qian, Zhe Wang, Chao Cao, Qi Gao and Jiwen Cai

J. Mar. Sci. Eng. 2025, 13(7), 1307; https://doi.org/10.3390/jmse13071307 - 5 Jul 2025

Viewed by 163

Abstract

Under the context of global climate change, sea-level rise and frequent storm surge events pose significant challenges to coastal areas. Protecting coastlines from erosion, mitigating socio-economic losses, and maintaining ecosystem balance are critical for the sustainable development of coastal zones. The concept of [...] Read more.

Under the context of global climate change, sea-level rise and frequent storm surge events pose significant challenges to coastal areas. Protecting coastlines from erosion, mitigating socio-economic losses, and maintaining ecosystem balance are critical for the sustainable development of coastal zones. The concept of “living shorelines” based on Nature-based Solutions (NbS) employs near-natural ecological restoration and protection measures. In low-energy coastal segments, natural materials are prioritized, while high-energy segments are supplemented with artificial structures. This approach not only enhances disaster resilience but also preserves coastal ecosystem stability and ecological functionality. This study constructs a coastal vitality evaluation system for Fujian Province, China, using the entropy weight method, integrating three dimensions: protective safety, ecological resilience, and economic vitality. Data from 2010 and 2020 were analyzed to assess the spatiotemporal evolution of coastal vitality. Results indicate that coastal vitality initially exhibited a spatial pattern of “low in the north, high in the center, and low in the south,” with vitality values ranging from 0.20 to 0.67 (higher values indicate stronger vitality). Over the past decade, ecological restoration projects have significantly improved coastal vitality, particularly in central and southern regions, where high-vitality segments increased markedly. Key factors influencing coastal vitality include water quality, cyclone intensity, biological shoreline length, and wetland area. NbS-aligned coastal management strategies and soft revetment practices have generated substantial ecological and economic benefits. To further enhance coastal vitality, region-specific approaches are recommended, emphasizing rational resource utilization, optimization of ecological and economic values, and the establishment of a sustainable evaluation framework. This study provides scientific insights for improving coastal protection capacity, ecological resilience, and economic potential. Full article

(This article belongs to the Special Issue Coastal Geochemistry: The Processes of Water–Sediment Interaction)

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6 pages, 168 KiB

Open AccessEditorial

Ocean Observations

by Chung-Ru Ho

J. Mar. Sci. Eng. 2025, 13(7), 1306; https://doi.org/10.3390/jmse13071306 - 5 Jul 2025

Viewed by 133

Abstract

Our Oceans cover more than 70% of the Earth’s surface, and thus various ocean engineering projects have been undertaken to utilize these vast resources effectively [...] Full article

(This article belongs to the Special Issue Ocean Observations)

28 pages, 25499 KiB

Open AccessArticle

A Combined CFD, Theoretical, and Experimental Approach for Improved Hydrodynamic Performance of a Clam Dredge System

by Rui You and Nathan H. Kennedy

J. Mar. Sci. Eng. 2025, 13(7), 1305; https://doi.org/10.3390/jmse13071305 - 4 Jul 2025

Viewed by 459

Abstract

This paper addresses the need for an integrated approach to develop an improved clam dredge system. Current designs often rely on empirical methods, resulting in a disconnect between theoretical models, computational simulations, and experimental validation. To bridge this gap, the study integrates computational [...] Read more.

This paper addresses the need for an integrated approach to develop an improved clam dredge system. Current designs often rely on empirical methods, resulting in a disconnect between theoretical models, computational simulations, and experimental validation. To bridge this gap, the study integrates computational fluid dynamics (CFD), experimental tests, and analytical methods to develop a clam dredge system. Firstly, the paper introduces an analytical tool that facilitates decision making by evaluating pump parameters, and to determine the operating point for various hose and nozzle parameters. This guides the parameter selection of pump, hose and jets for maximum performance. Secondly, CFD is utilized to analyze flow behavior, enabling the design of internal nozzle geometries that minimize head losses and maximize the scouring effect. A full-scale experimental measurement was conducted to validate computational results. Furthermore, a replica manifold is constructed using 3D printing and tested, demonstrating improvements in jet speed with both original and new nozzle designs. Analytical results indicate that increasing hose length reduces BHP, flow rate, and jet velocity, while increasing hose or jet diameter boosts BHP and flow but reduces jet speed due to pressure drops. Switching pumps reduced power consumption by 10.5% with minimal speed loss. The CFD analysis optimized nozzle design, reducing jet loss and enhancing efficiency. The proposed slit nozzle design reduces the loss coefficient by 85.24% in small-scale runs and by 83% in full-scale runs compared to the original circular jet design. The experiments confirmed the pressure differences between the CFD and experimental tests are within 10%, and demonstrated that rectangular jets increase speed by 9% and seafloor force by 19%. This paper improved the hydrodynamic design of the clam dredge system, and provides a framework for future dredge system designs. Full article

(This article belongs to the Section Ocean Engineering)

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21 pages, 9015 KiB

Open AccessArticle

Energetics of Eddy–Mean Flow Interaction in the Kuroshio Current Region

by Yang Wu, Dalei Qiao, Chengyan Liu, Liangjun Yan, Kechen Liu, Jiangchao Qian, Qing Qin, Jianfen Wei, Heyou Chang, Kai Zhou, Zhengdong Qi, Xiaorui Zhu, Jing Li, Yuzhou Zhang and Hongtao Guo

J. Mar. Sci. Eng. 2025, 13(7), 1304; https://doi.org/10.3390/jmse13071304 - 3 Jul 2025

Viewed by 273

Abstract

A comprehensive diagnosis of eddy–mean flow interaction in the Kuroshio Current (KC) region and the associated energy conversion pathway is conducted employing a state-of-the-art high-resolution global ocean–sea ice coupled model. The spatial distributions of the energy reservoirs and their conversions exhibit significant complexity. [...] Read more.

A comprehensive diagnosis of eddy–mean flow interaction in the Kuroshio Current (KC) region and the associated energy conversion pathway is conducted employing a state-of-the-art high-resolution global ocean–sea ice coupled model. The spatial distributions of the energy reservoirs and their conversions exhibit significant complexity. The cross-stream variation is found in the energy conversion pattern in the along-coast region, whereas a mixed positive–negative conversion pattern is observed in the off-coast region. Considering the area-integrated conversion rates between energy reservoirs, barotropic and baroclinic instabilities dominate the energy transferring from the mean flow to eddy field in the KC region. When the KC separates from the coast, it becomes highly unstable and the energy conversion rates intensify visibly; moreover, the local variations of the energy conversion are significantly influenced by the topography in the KC extension region. The mean available potential energy is the total energetic source to drive the barotropic and baroclinic energy pathway in the whole KC region, while the mean kinetic energy supplies the total energy in the extension region. For the whole KC region, the mean current transfers 84.9 GW of kinetic energy and 37.3 GW of available potential energy to the eddy field. The eddy kinetic energy is generated by mixed barotropic and baroclinic processes, amounting to 84.9 GW and 15.03 GW, respectively, indicating that topography dominates the generation of mesoscale eddy. Mean kinetic energy amounts to 11.08 GW of power from the mean available potential energy and subsequently supplies the barotropic pathway. Full article

(This article belongs to the Special Issue Regional Ocean Dynamics in a Warming Climate: Insights from Modeling and Observations)

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23 pages, 4005 KiB

Open AccessArticle

A Ship Underwater Radiated Noise Prediction Method Based on Semi-Supervised Ensemble Learning

by Xin Huang, Rongwu Xu and Ruibiao Li

J. Mar. Sci. Eng. 2025, 13(7), 1303; https://doi.org/10.3390/jmse13071303 - 3 Jul 2025

Viewed by 131

Abstract

Accurate prediction of ship underwater radiated noise (URN) during navigation is critical for evaluating acoustic stealth performance and analyzing detection risks. However, the labeled data available for the training of URN prediction model is limited. Semi-supervised learning (SSL) can improve the model performance [...] Read more.

Accurate prediction of ship underwater radiated noise (URN) during navigation is critical for evaluating acoustic stealth performance and analyzing detection risks. However, the labeled data available for the training of URN prediction model is limited. Semi-supervised learning (SSL) can improve the model performance by using unlabeled data in the case of a lack of labeled data. Therefore, this paper proposes an SSL method for URN prediction. First, an anti-perturbation regularization is constructed using unlabeled data to optimize the objective function of EL, which is then used in the Genetic algorithm to adaptively optimize base learner weights, to enhance pseudo-label quality. Second, a semi-supervised ensemble (ESS) framework integrating dynamic pseudo-label screening and uncertainty bias correction (UBC) is established, which can dynamically select pseudo-labels based on local prediction performance improvement and reduce the influence of pseudo-labels’ uncertainty on the model. Experimental results of the cabin model and sea trials of the ship demonstrate that the proposed method reduces prediction errors by up to 65.5% and 62.1% compared to baseline supervised and semi-supervised regression models, significantly improving prediction accuracy. Full article

(This article belongs to the Section Ocean Engineering)

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21 pages, 6046 KiB

Open AccessArticle

Mechanical Properties of Granular Sea Ice Under Uniaxial Compression: A Comparison of Piled and Level Ice

by Yubo Liu, Qingkai Wang, Peng Lu, Zhijun Li, Zhixing Li, Zhi Zong and Limin Zhang

J. Mar. Sci. Eng. 2025, 13(7), 1302; https://doi.org/10.3390/jmse13071302 - 3 Jul 2025

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Abstract

The proportion of granular ice in sea ice layers has markedly increased due to global warming. To investigate the uniaxial compressive behavior of granular sea ice, we conducted a series of experiments using natural piled and level ice samples collected from the Bohai [...] Read more.

The proportion of granular ice in sea ice layers has markedly increased due to global warming. To investigate the uniaxial compressive behavior of granular sea ice, we conducted a series of experiments using natural piled and level ice samples collected from the Bohai Sea. A total of 311 specimens were tested under controlled temperature conditions ranging from −15 °C to −2 °C and strain rates varying from 10⁻⁵ to 10⁻² s⁻¹. The effects of porosity, strain rate, and failure modes were studied. The results show that both the uniaxial compressive strength and uniaxial compressive elastic modulus were dependent on strain rate and porosity. Granular sea ice exhibited a non-monotonic strength dependence on strain rate, with the strength increasing in the ductile regime and decreasing in the brittle regime. In contrast, the elastic modulus increased monotonically with the strain rate. Both the strength and elastic modulus decreased with increasing porosity. Level ice consistently demonstrated higher strength and an elastic modulus than piled ice at equivalent porosities. Unified parametric models were developed to describe both properties across a wide range of strain rates encompassing the ductile-to-brittle (DBT) regime. The experimental results show that, as porosity decreased, the transition strain rate of granular sea ice shifted from 2.34 × 10⁻³ s⁻¹ at high porosity (45%) to 1.42 × 10⁻⁴ s⁻¹ at low porosity (10%) for level ice and 1.87 × 10⁻³ s⁻¹ to 1.19 × 10⁻³ s⁻¹ for piled ice. These results were compared with classical columnar ice models. These findings are useful for informing the design of vessel and coastal structures intended for use in ice-covered waters. Full article

(This article belongs to the Special Issue Navigation Performance and Experimental Research of Ships in Ice-Covered Areas)

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40 pages, 7119 KiB

Open AccessArticle

Optimizing Intermodal Port–Inland Hub Systems in Spain: A Capacitated Multiple-Allocation Model for Strategic and Sustainable Freight Planning

by José Moyano Retamero and Alberto Camarero Orive

J. Mar. Sci. Eng. 2025, 13(7), 1301; https://doi.org/10.3390/jmse13071301 - 2 Jul 2025

Viewed by 210

Abstract

This paper presents an enhanced hub location model tailored to port–hinterland logistics planning, grounded in the Capacitated Multiple-Allocation Hub Location Problem (CMAHLP). The formulation incorporates nonlinear cost structures, hub-specific operating costs, adaptive capacity constraints, and a feasibility condition based on the Social Net [...] Read more.

This paper presents an enhanced hub location model tailored to port–hinterland logistics planning, grounded in the Capacitated Multiple-Allocation Hub Location Problem (CMAHLP). The formulation incorporates nonlinear cost structures, hub-specific operating costs, adaptive capacity constraints, and a feasibility condition based on the Social Net Present Value (NPVsocial) to support the design of intermodal freight networks under asymmetric spatial and socio-environmental conditions. The empirical case focuses on Spain, leveraging its strategic position between Asia, North Africa, and Europe. The model includes four major ports—Barcelona, Valencia, Málaga, and Algeciras—as intermodal gateways connected to the 47 provinces of peninsular Spain through calibrated cost matrices based on real distances and mode-specific road and rail costs. A Genetic Algorithm is applied to evaluate 120 scenarios, varying the number of active hubs (4, 6, 8, 10, 12), transshipment discounts (α = 0.2 and 1.0), and internal parameters. The most efficient configuration involved 300 generations, 150 individuals, a crossover rate of 0.85, and a mutation rate of 0.40. The algorithm integrates guided mutation, elitist reinsertion, and local search on the top 15% of individuals. Results confirm the central role of Madrid, Valencia, and Barcelona, frequently accompanied by high-performance inland hubs such as Málaga, Córdoba, Jaén, Palencia, León, and Zaragoza. Cities with active ports such as Cartagena, Seville, and Alicante appear in several of the most efficient network configurations. Their recurring presence underscores the strategic role of inland hubs located near seaports in supporting logistical cohesion and operational resilience across the system. The COVID-19 crisis, the Suez Canal incident, and the persistent tensions in the Red Sea have made clear the fragility of traditional freight corridors linking Asia and Europe. These shocks have brought renewed strategic attention to southern Spain—particularly the Mediterranean and Andalusian axes—as viable alternatives that offer both geographic and intermodal advantages. In this evolving context, the contribution of southern hubs gains further support through strong system-wide performance indicators such as entropy, cluster diversity, and Pareto efficiency, which allow for the assessment of spatial balance, structural robustness, and optimal trade-offs in intermodal freight planning. Southern hubs, particularly in coordination with North African partners, are poised to gain prominence in an emerging Euro–Maghreb logistics interface that demands a territorial balance and resilient port–hinterland integration. Full article

(This article belongs to the Section Coastal Engineering)

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20 pages, 17089 KiB

Open AccessArticle

Sedimentary Characteristics and Genetic Mechanisms of Non-Evaporitic Gypsum in a Half-Graben Basin: A Case Study from the Zhanhua Sag, Bohai Bay Basin, China

by Muxin Cai, Jianguo Zhang, Zaixing Jiang, Junliang Li, Tao Meng, Peng Liu and Chao Jiang

J. Mar. Sci. Eng. 2025, 13(7), 1300; https://doi.org/10.3390/jmse13071300 - 2 Jul 2025

Viewed by 250

Abstract

Gypsum and salt rocks have been proven to act as seals for abundant oil and gas reserves on a global scale, with significant potential for hydrocarbon preservation and evolution. Notably, the sedimentary dynamics of non-evaporitic gypsum in terrestrial half-graben basins remain underexplored, particularly [...] Read more.

Gypsum and salt rocks have been proven to act as seals for abundant oil and gas reserves on a global scale, with significant potential for hydrocarbon preservation and evolution. Notably, the sedimentary dynamics of non-evaporitic gypsum in terrestrial half-graben basins remain underexplored, particularly regarding its genetic link to hydrocarbon accumulation in interbedded mudstones. This study is based on the Zhanhua Sag, in which thick-layered gypsum rocks with dark mudstone are deposited. The gypsum crystals show the intermittent deposition characteristics. The cumulative thickness of the gypsum-containing section reaches a maximum of over 110 m. The spatial distribution of gypsum thickness correlates strongly with the location of deep-seated faults. The strontium and sulfur isotopes of gypsum indicate deep hydrothermal fluids as mineral sources, and negative oxygen isotope excursions also suggest that gypsum layers precipitated in situ from hot brine. Total organic carbon and Rock-Eval data indicate that the deep-lake gypsum rock system has excellent hydrocarbon potential, especially in the mudstone interlayers. This study developed a depositional model of deep-lake gypsum rocks with thermal brine genesis in half-graben basins. The gypsum-bearing system is rich in mudstone interlayers. These gypsum–mudstone interbeds represent promising targets for shale oil exploration after the initial breakthrough during the extraction process. These insights provide a theoretical framework for understanding gypsum-related petroleum systems in half-graben basins across the globe, offering guidance for hydrocarbon exploration in analogous sedimentary environments. Full article

(This article belongs to the Section Geological Oceanography)

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24 pages, 28055 KiB

Open AccessArticle

Sequence Stratigraphic and Geochemical Records of Paleo-Sea Level Changes in Upper Carboniferous Mixed Clastic–Carbonate Successions in the Eastern Qaidam Basin

by Yifan Li, Xiaojie Wei, Kui Liu and Kening Qi

J. Mar. Sci. Eng. 2025, 13(7), 1299; https://doi.org/10.3390/jmse13071299 - 2 Jul 2025

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Abstract

The Upper Carboniferous strata in the eastern Qaidam Basin, comprising several hundred meters of thick, mixed clastic–carbonate successions that have been little reported or explained, provide an excellent geological record of paleoenvironmental and paleo-sea level changes during the Late Carboniferous icehouse period. This [...] Read more.

The Upper Carboniferous strata in the eastern Qaidam Basin, comprising several hundred meters of thick, mixed clastic–carbonate successions that have been little reported or explained, provide an excellent geological record of paleoenvironmental and paleo-sea level changes during the Late Carboniferous icehouse period. This tropical carbonate–clastic system offers critical constraints for correlating equatorial sea level responses with high-latitude glacial cycles during the Late Paleozoic Ice Age. Based on detailed outcrop observations and interpretations, five facies assemblages, including fluvial channel, tide-dominated estuary, wave-dominated shoreface, tide-influenced delta, and carbonate-dominated marine, have been identified and organized into cyclical stacking patterns. Correspondingly, four third-order sequences were recognized, each composed of lowstand, transgressive, and highstand system tracts (LST, TST, and HST). LST is generally dominated by fluvial channels as a result of river juvenation when the sea level falls. The TST is characterized by tide-dominated estuaries, followed by retrogradational, carbonated-dominated marine deposits formed during a period of sea level rise. The HST is dominated by aggradational marine deposits, wave-dominated shoreface environments, or tide-influenced deltas, caused by subsequent sea level falls and increased debris supply. The sequence stratigraphic evolution and geochemical records, based on carbon and oxygen isotopes and trace elements, suggest that during the Late Carboniferous period, the eastern Qaidam Basin experienced at least four significant sea level fluctuation events, and an overall long-term sea level rise. These were primarily driven by the Gondwana glacio-eustasy and regionally ascribed to the Paleo-Tethys Ocean expansion induced by the late Hercynian movement. Assessing the history of glacio-eustasy-driven sea level changes in the eastern Qaidam Basin is useful for predicting the distribution and evolution of mixed cyclic succession in and around the Tibetan Plateau. Full article

(This article belongs to the Topic Formation Mechanism and Quantitative Evaluation of Deep to Ultra-Deep High-Quality Reservoirs)

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