Journal of Marine Science and Engineering

15 pages, 2759 KiB

Open AccessArticle

Dynamic Response Analysis of a Novel Tension-Leg Dual-Module Offshore Wind Turbine System During Both Installation and Removal Processes

by Shi Liu, Xinran Guo, Yi Yang, Hongxing Wang, Shenghua Wei, Nianxin Ren and Chaohe Chen

J. Mar. Sci. Eng. 2025, 13(5), 888; https://doi.org/10.3390/jmse13050888 (registering DOI) - 29 Apr 2025

Abstract

To facilitate both the installation and the removal of floating offshore wind turbines (FOWTs), a novel tension-leg dual-module offshore wind turbine system has been proposed. This system primarily consists of a DTU 10 MW wind turbine (WT) module and a supporting tension-leg platform [...] Read more.

To facilitate both the installation and the removal of floating offshore wind turbines (FOWTs), a novel tension-leg dual-module offshore wind turbine system has been proposed. This system primarily consists of a DTU 10 MW wind turbine (WT) module and a supporting tension-leg platform (TLP) module. Considering both mechanical and hydrodynamic coupling effects of the dual-module system, this study focuses on its dynamic responses during both the installation and the removal of the WT module under typical sea states. The effect of different installation vessel positions and key parameters of the clamping device on the dynamic response of the system during the WT module removal has been clarified. Based on the findings, preliminary recommendations are provided regarding the optimal positioning of the installation vessel and the optimal design parameters of the clamping device. Furthermore, an auxiliary sleeve has been proposed to facilitate the WT module removal. The results indicate that the application of the auxiliary sleeve can significantly improve the dynamic response of the system. The results of this study can serve as a reference for the design, installation, and removal of floating offshore wind turbines. Full article

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

22 pages, 8698 KiB

Open AccessArticle

Integrating Actual Decision-Making Requirements for Intelligent Collision Avoidance Strategy in Multi-Ship Encounter Situations

by Yun Li, Yu Peng and Jian Zheng

J. Mar. Sci. Eng. 2025, 13(5), 887; https://doi.org/10.3390/jmse13050887 (registering DOI) - 29 Apr 2025

Abstract

Driven by the commercialization of intelligent ships, the increasingly complex mixed maritime traffic environment presents significant challenges for collision avoidance between multiple ships due to cognitive and behavioral differences between intelligent and traditional ships. Therefore, it is essential to develop a human-like collision [...] Read more.

Driven by the commercialization of intelligent ships, the increasingly complex mixed maritime traffic environment presents significant challenges for collision avoidance between multiple ships due to cognitive and behavioral differences between intelligent and traditional ships. Therefore, it is essential to develop a human-like collision avoidance strategy that incorporates traditional navigational experience and handling practices, enhancing explainability and autonomy. By addressing the actual decision-making needs for predicting other ships’ intentions and considering potential risk impacts, a hierarchical strategy is designed that first seeks course direction adjustment and then determines the magnitude of adjustment. A direction adjustment intention estimation model is proposed, accounting for risk membership and COLREGS, to predict other ships’ collision avoidance intentions. Additionally, an intention influence model and a state influence model are introduced to design decision-making objectives, forming an optimization function based on angle range and maneuvering time constraints to determine the appropriate adjustment magnitude. The results demonstrate the strategy’s effectiveness across various scenarios. Specifically, the distance between ships increased by nearly 25% during the process, significantly enhancing safety. It is worth mentioning that the model has the potential to enhance intelligent ships’ capabilities in complex situational handling and intention understanding. Full article

(This article belongs to the Section Ocean Engineering)

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26 pages, 7611 KiB

Open AccessArticle

An Ensemble Classification Method Based on a Stacking Strategy for Ship Type Classification with AIS Data

by Lei Deng, Shichen Yang, Limin Jia and Danyang Geng

J. Mar. Sci. Eng. 2025, 13(5), 886; https://doi.org/10.3390/jmse13050886 (registering DOI) - 29 Apr 2025

Abstract

Ship type (e.g., Cargo, Tanker and Fishing) classification is crucial for marine management, environmental protection, and maritime safety, as it enhances navigation safety and aids regulatory agencies in combating illegal activities. Traditional ship type classification methods with AIS data are often plagued by [...] Read more.

Ship type (e.g., Cargo, Tanker and Fishing) classification is crucial for marine management, environmental protection, and maritime safety, as it enhances navigation safety and aids regulatory agencies in combating illegal activities. Traditional ship type classification methods with AIS data are often plagued by problems such as data imbalance, insufficient feature extraction, reliance on single-model approaches, or unscientific model combination methods, which reduce the accuracy of classification. In this paper, we propose an ensemble classification method based on a stacking strategy to overcome these challenges. We apply the SMOTE technique to balance the dataset by generating minority class samples. Then, a more comprehensive ship behavior model is developed by combining static and dynamic features. A stacking strategy is adopted for the classification, integrating multiple tree structure-based classifiers to improve classification performance. The experimental results show that the ensemble classification method based on the stacking strategy outperforms traditional classifiers such as CatBoost, Random Forest, Decision Tree, LightGBM, and the ensemble classification method, especially in terms of improving classification precision, recall, F1 score, ROC curve, and AUC. This method improves the accuracy of ship type recognition, and it is suitable to real-time online classification, which is helpful for applications in marine safety monitoring, law enforcement, and illegal fishing detection. Full article

(This article belongs to the Section Ocean Engineering)

15 pages, 6229 KiB

Open AccessArticle

Monitoring of Rhopilema esculentum Resources in Hangzhou Bay in 2024 and Analysis of Bloom Causes

by Guoqiang Xu and Yongdong Zhou

J. Mar. Sci. Eng. 2025, 13(5), 885; https://doi.org/10.3390/jmse13050885 (registering DOI) - 29 Apr 2025

Abstract

To investigate the spatiotemporal distribution and causes of blooms of Rhopilema esculentum in Hangzhou Bay during 2024, this study investigated its growth characteristics, including umbrella diameter and body weight, along with environmental factors, spatiotemporal dynamics and yield variations. The analysis was based on [...] Read more.

To investigate the spatiotemporal distribution and causes of blooms of Rhopilema esculentum in Hangzhou Bay during 2024, this study investigated its growth characteristics, including umbrella diameter and body weight, along with environmental factors, spatiotemporal dynamics and yield variations. The analysis was based on the 2024 monitoring data of R. esculentum resources in Hangzhou Bay, together with relevant social research data. The results showed that umbrella diameter and body weight increased over time at all monitoring points. The growth rate of the R. esculentum umbrella diameter declined gradually over time, whereas that of body weight rapidly increased. The daily growth rate of umbrella diameter in the water of Tangnao and Xiaoji Mountains was significantly higher than that in the waters of Tanxu Mountain. A sharp drop in salinity caused by Xin’anjiang Reservoir flood discharge from the 23rd to 28th June was the primary cause of the R. esculentum blooms in Hangzhou Bay. During the special R. esculentum fishing period in the summer fishing moratorium, R. esculentum was mainly distributed in the southern and eastern Hangzhou waters, with a maximum daily yield of 28,000 kg/day. After the 16th, R. esculentum production expanded across the entire bay, with blooms also occurring in Xiangshan Bay and Liuheng, reaching a production peak of 44,000 kg/day. In 2024, R. esculentum production in Hangzhou Bay totalled 250,000 tonnes, breaking historical records. This study revealed the 2024 growth and spatiotemporal dynamics of R. esculentum in Hangzhou Bay, providing a reference for the rational use and protection of the species and revealing the causes of the unprecedented blooms. Full article

(This article belongs to the Section Marine Ecology)

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28 pages, 7300 KiB

Open AccessArticle

Enhancing Trajectory Tracking Performance of Underwater Gliders Using Finite-Time Sliding Mode Control Within a Reinforcement Learning Framework

by Guohui Wang, Jianing Yu and Yanan Yang

J. Mar. Sci. Eng. 2025, 13(5), 884; https://doi.org/10.3390/jmse13050884 (registering DOI) - 29 Apr 2025

Abstract

Underwater gliders, as autonomous underwater vehicles, are integral to oceanographic research, environmental monitoring, and military applications. Given the intricate and ever-changing underwater environment, the precise management of an underwater glider’s dive depth and pitch angle is imperative for optimal functionality.This study introduces a [...] Read more.

Underwater gliders, as autonomous underwater vehicles, are integral to oceanographic research, environmental monitoring, and military applications. Given the intricate and ever-changing underwater environment, the precise management of an underwater glider’s dive depth and pitch angle is imperative for optimal functionality.This study introduces a finite-time sliding mode control method for controlling dive depth and pitch angle of underwater gliders. It incorporates a radial basis function neural network in a critic–actor reinforcement learning framework, enhancing navigational performance in difficult conditions. Sea trial data are used to create a dynamic model for the underwater glider, which is then used to design a control law. Sliding mode control is used to align the dive depth and pitch angle with the desired trajectory. Actor and critic neural networks are used to handle disturbances and evaluate error costs. By incorporating standard deviation update technique into actor and critic neural networks, along with weight updates, we improve controller stability and reduce errors in maintaining dive depth and pitch angle. Our approach is proven to be more effective than traditional SMC and reinforcement learning SMC methods in trajectory tracking, even in the presence of disturbances, as shown in the simulation results. Full article

(This article belongs to the Section Ocean Engineering)

22 pages, 21962 KiB

Open AccessArticle

Experimental Study on the Reinforcement of Calcareous Sand Using Combined Microbial-Induced Carbonate Precipitation (MICP) and Festuca arundinacea Techniques

by Xiuqiong Deng, Ziyu Wang, Yuchun Qin, Liang Cao, Peng Cao, Yu Xie and Yingqi Xie

J. Mar. Sci. Eng. 2025, 13(5), 883; https://doi.org/10.3390/jmse13050883 (registering DOI) - 29 Apr 2025

Abstract

Combining the Microbial-Induced Calcium Carbonate Precipitation (MICP) technique with plants to reinforce calcareous sand slopes on reef islands is expected to achieve both reinforcement and economic benefits. In this study, MICP was combined with Festuca arundinacea (MICP-FA) for calcareous sand reinforcement. Based on [...] Read more.

Combining the Microbial-Induced Calcium Carbonate Precipitation (MICP) technique with plants to reinforce calcareous sand slopes on reef islands is expected to achieve both reinforcement and economic benefits. In this study, MICP was combined with Festuca arundinacea (MICP-FA) for calcareous sand reinforcement. Based on water retention and scanning electron microscopy (SEM) tests, the water retention performance and mechanism of MICP-reinforced calcareous sand under different cementation solution concentrations and cementation cycles were analyzed. The growth adaptability of Festuca arundinacea was evaluated under different bacteria solution concentrations, cementation solution concentrations and cementation cycles. The engineering applicability of MICP-FA-reinforced calcareous sand was evaluated by wind erosion tests, and the synergistic reinforcement mechanism was analyzed. The results show that with the increase in the cementation solution concentration and cementation cycles, more calcium carbonate filled and adhered to the calcareous sand particles, significantly improving the water retention performance. MICP-FA can enhance the wind erosion resistance of calcareous sand. This synergistic mechanism lies in the surface cementation effect of MICP and the deep anchoring effect of plant roots. This study provides theoretical basis and technical guidance for engineering applications in calcareous sand areas. Full article

(This article belongs to the Special Issue Advances in Marine Geological and Geotechnical Hazards)

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14 pages, 2308 KiB

Open AccessBrief Report

Pilot-Scale Cultivation of Seaweed (Undaria pinnatifida) Along an Offshore Wind Farm in Southwestern Korea

by Dongmun Choi, Hyung-Gon Lee, Yun-Hwan Jung, Dae-Won Lee, Jeonghoon Han, Ji-Yeon Hyeon and Young-Ung Choi

J. Mar. Sci. Eng. 2025, 13(5), 882; https://doi.org/10.3390/jmse13050882 (registering DOI) - 29 Apr 2025

Abstract

Marine environments provide a unique opportunity to blend offshore wind energy production and marine fishery activities as complementary technologies. This study investigated the morphological characteristics (length and weight) and biomass yield of seaweed (Undaria pinnatifida) in a model marine environment with [...] Read more.

Marine environments provide a unique opportunity to blend offshore wind energy production and marine fishery activities as complementary technologies. This study investigated the morphological characteristics (length and weight) and biomass yield of seaweed (Undaria pinnatifida) in a model marine environment with mariculture within an offshore wind farm in southwestern Korea. The mean lengths in the first cultivation trials of U. pinnatifida sporophytes increased from 1.8 ± 0.1 cm in November 2021 to 120–170 cm in March 2022 (density, 39.8 plants m⁻¹; final wet weight, 98.6–249.1 g (mean 146.8 ± 20.4 g, n = 20 ind.); yield 5842 g m⁻¹). Further, for the second cultivation trial, the length of the sporophytes increased from 1.5 ± 0.1 cm in November 2021 to 120–150 cm in April 2022 (density, 49.3 plants m⁻¹; final wet weight, 83.0–251.6 g (mean 155.7 ± 19.0 g; n = 20 ind.); yield, 7676 g m⁻¹), and, owing to the increase in water temperature and light intensity due to seasonal changes around the offshore wind power farm, the second cultivation trials showed signs of chlorosis. Considering the environment, we judged seaweed growth to be normal. Therefore, when applying this model to grow U. pinnatifida, seasonal temperature changes, the purpose of the product, and the nutritional status of the open-sea area should be considered. These results may improve seaweed farming in offshore wind farms in the future. Full article

(This article belongs to the Section Ocean Engineering)

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20 pages, 10754 KiB

Open AccessArticle

Late Pleistocene Climate–Weathering Dynamics in Bohai Bay: High-Resolution Sedimentary Proxies and Their Global Paleoclimatic Synchronicity

by Yanxiang Lei, Xinyi Liu, Yanhui Zhang, Lei He, Zengcai Zhao, Liujuan Xie and Siyuan Ye

J. Mar. Sci. Eng. 2025, 13(5), 881; https://doi.org/10.3390/jmse13050881 (registering DOI) - 29 Apr 2025

Abstract

Understanding the climate–weathering coupling mechanisms remains pivotal for interpreting global glacial–interglacial cycles, yet advancements have been constrained by the limited high-resolution sedimentary archives. The newly acquired BXZK2017-2 borehole (30.5 m core) from Bohai Bay provides an exceptional sedimentary sequence to investigate the Late [...] Read more.

Understanding the climate–weathering coupling mechanisms remains pivotal for interpreting global glacial–interglacial cycles, yet advancements have been constrained by the limited high-resolution sedimentary archives. The newly acquired BXZK2017-2 borehole (30.5 m core) from Bohai Bay provides an exceptional sedimentary sequence to investigate the Late Quaternary climate–weathering interactions. Through an integrated high-resolution chronostratigraphic framework (AMS ¹⁴C and OSL dating) coupled with multi-proxy sedimentological analyses (major element geochemistry and granulometric parameters), we reconstructed the chemical–weathering dynamics in the Bohai coastal region since the Late Pleistocene. Our findings revealed four distinct climate-weathering phases that correlate with the regional paleoenvironmental evolution and global climate perturbations: (1) enhanced weathering during mid-MIS3 to ~37.5 cal kyr BP (Chemical Index of Alteration (CIA): 55.9–62.2), corresponding to regional warming and strengthened summer monsoon circulation; (2) weathering minimum in late MIS3 through early–mid-MIS2 (37.5–14.8 cal kyr BP, CIA < 55), marking the peak aridity before the Last Glacial Maximum; (3) maximum weathering intensity from mid-MIS2 to early MIS1 (14.8–3.34 cal kyr BP, CIA: 65–68), documenting the postglacial humidification driven by the intensified East Asian Summer Monsoon; (4) renewed weathering decline during the Neoglacial (3.34 cal kyr BP-present, CIA: 59–63), coinciding with the late Holocene cooling events. Remarkably, this study identifies a striking synchronicity between the CIA in marine drill cores and δ¹⁸O records derived from Greenland ice cores. Our results indicate that chemical weathering proxies from marginal sea sediments can serve as robust recorders of post-Late Pleistocene climate variability, establishing a new proxy framework for global paleoclimate comparative research. Full article

(This article belongs to the Topic Human Impact on Groundwater Environment, 2nd Edition)

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15 pages, 8753 KiB

Open AccessArticle

Experimental and Numerical Investigation on Mechanical Properties of Large-Diameter Metallurgically Clad Pipes

by Feng Wang, Yanan Gao, Zhiguo Hu, Shuo Yang, Zhenying Cui, Rui Fu and Lin Yuan

J. Mar. Sci. Eng. 2025, 13(5), 880; https://doi.org/10.3390/jmse13050880 (registering DOI) - 29 Apr 2025

Abstract

Bimetallic-clad pipes demonstrate exceptional advantages in transporting corrosive oil and gas through the combination of the load-carrying capacity of the base material and the anti-corrosive function of the thin layer of corrosion-resistant alloy. This study investigates the mechanical properties of 24-inch X65 + [...] Read more.

Bimetallic-clad pipes demonstrate exceptional advantages in transporting corrosive oil and gas through the combination of the load-carrying capacity of the base material and the anti-corrosive function of the thin layer of corrosion-resistant alloy. This study investigates the mechanical properties of 24-inch X65 + Alloy625 metallurgically clad pipes through experimental tests and finite element analysis. Uniaxial tensile testing with digital image correlation reveals uniform deformation between the base and clad layers until interfacial failure initiates at an average strain threshold of 34.17%. Microstructural characterization shows continuous metallurgical bonding, with the X65 layer exhibiting polygonal ferrite and bainitic phases, contrasting with the austenitic equiaxed grain structure of Alloy625. In terms of numerical modeling, finite element analyses that consider both initial geometric imperfections and manufacturing-induced residual stresses are performed to evaluate the bending response of the clad pipe. The effect of initial ovality and residual stresses on its bending capacity is also studied. Full article

(This article belongs to the Special Issue Advanced Research in Flexible Riser and Pipelines)

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29 pages, 3199 KiB

Open AccessArticle

A Trajectory Tracking Control Method for 6 DoF UUV Based on Event Triggering Mechanism

by Yakang Ju, Wenyu Cai, Meiyan Zhang and Hao Chen

J. Mar. Sci. Eng. 2025, 13(5), 879; https://doi.org/10.3390/jmse13050879 (registering DOI) - 28 Apr 2025

Abstract

Trajectory tracking control refers to the movement of an unmanned underwater vehicle (UUV) along a desired trajectory, which is a critical technology for the underwater tasks of UUVs. However, in actual scenarios, the reaction torque of propellers induces roll motion in UUVs, and [...] Read more.

Trajectory tracking control refers to the movement of an unmanned underwater vehicle (UUV) along a desired trajectory, which is a critical technology for the underwater tasks of UUVs. However, in actual scenarios, the reaction torque of propellers induces roll motion in UUVs, and the communication resource and computational resource of UUVs are limited, which affects the trajectory tracking performance of UUVs severely. Hence, this paper introduces an event triggering mechanism to design the double-loop integrated sliding mode control (EDLISMC), which is used for the trajectory tracking control of UUVs. This method designs the kinematic model and dynamic model of 6 degree of freedom (DoF) UUVs under the influence of reaction torque. Then, this method derives the dual loop integral sliding mode controller and designs the event triggering mechanism based on the relative threshold to reduce unnecessary control signals and improve the control efficiency of UUVs. In addition, this method uses a positive lower bound method to verify that the proposed event triggering mechanism does not have Zeno behavior and adopts the Lyapunov theorem to analyze the stability of EDLISMC. Finally, this paper conducts simulations on the simulink component of MATLAB. The relevant simulation proves that the proposed method can complete the trajectory tracking control of UUVs under the influence of reaction torque and it is superior to other methods in terms of resource consumption. Full article

(This article belongs to the Section Ocean Engineering)

25 pages, 20538 KiB

Open AccessArticle

Leader-Following-Based Optimal Fault-Tolerant Consensus Control for Air–Marine–Submarine Heterogeneous Systems

by Yandong Li, Longqi Li, Ling Zhu, Zehua Zhang and Yuan Guo

J. Mar. Sci. Eng. 2025, 13(5), 878; https://doi.org/10.3390/jmse13050878 (registering DOI) - 28 Apr 2025

Viewed by 17

Abstract

This paper mainly investigates the fault-tolerant consensus problem in heterogeneous multi-agent systems. Firstly, a control model of a leader–follower heterogeneous multi-agent system (HMAS) composed of multiple unmanned aerial vehicles (UAVs), multiple unmanned surface vehicles (USVs), and multiple unmanned underwater vehicles (UUVs) is established. [...] Read more.

This paper mainly investigates the fault-tolerant consensus problem in heterogeneous multi-agent systems. Firstly, a control model of a leader–follower heterogeneous multi-agent system (HMAS) composed of multiple unmanned aerial vehicles (UAVs), multiple unmanned surface vehicles (USVs), and multiple unmanned underwater vehicles (UUVs) is established. Then, for the fault-tolerant control (FTC) consensus problem of heterogeneous systems under partial actuator failures and interruption failures, an optimal FTC protocol for heterogeneous multi-agent systems based on the control allocation algorithm is designed. The derived optimal FTC protocol is applied to the heterogeneous system. The asymptotic stability of the protocol is proved by the Lyapunov stability theory. Finally, the effectiveness of the control strategy is verified through simulation tests. Full article

(This article belongs to the Special Issue The Control and Navigation of Autonomous Surface Vehicles)

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20 pages, 6056 KiB

Open AccessArticle

Inter-Element Phase Error Compensated Calibration Method for USBL Arrays

by Dejinxuan Zhang, Guangpu Zhang, Xu Zhao, Nan Zou, Jin Fu and Yuanxin Bai

J. Mar. Sci. Eng. 2025, 13(5), 877; https://doi.org/10.3390/jmse13050877 (registering DOI) - 28 Apr 2025

Viewed by 54

Abstract

This study addresses the critical limitation of existing Ultra-Short Baseline (USBL) calibration algorithms in handling transducer positional errors and inter-element phase errors. We propose a novel positioning-calibration model based on vector projection theorem. The model achieves two key innovations: it eliminates the influence [...] Read more.

This study addresses the critical limitation of existing Ultra-Short Baseline (USBL) calibration algorithms in handling transducer positional errors and inter-element phase errors. We propose a novel positioning-calibration model based on vector projection theorem. The model achieves two key innovations: it eliminates the influence of inter-element positional errors through its structural design, and, for the first time, incorporates inter-element phase errors from acoustic array measurements as observational parameters to establish joint estimation equations for system installation angle errors and inter-element phase errors. The estimation process is implemented using an unscented Kalman filter (UKF). Simulation results demonstrate that the UKF outperforms the Gauss–Newton method (GNM), achieving estimation errors for installation angles and phase errors within 0.05°. Comparative evaluations confirm the model’s superiority over conventional calibration methods in accurately estimating installation angles under transducer positional errors. Field experiments further validate the algorithm’s effectiveness in real-world marine environments, successfully estimating system installation angle errors and inter-element phase errors to enhance final target positioning accuracy. This approach provides a practical solution to persistent calibration challenges in USBL systems. Full article

(This article belongs to the Special Issue Advanced Research in Guidance, Navigation, and Control for Autonomous Surface Vehicle)

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32 pages, 12574 KiB

Open AccessArticle

Stochastic and Nonlinear Dynamic Response of Drillstrings in Deepwater Riserless Casing Drilling Operation

by He Li, Guodong Cheng, Shiming Zhou, Wenyang Shi and Jieli Wang

J. Mar. Sci. Eng. 2025, 13(5), 876; https://doi.org/10.3390/jmse13050876 (registering DOI) - 28 Apr 2025

Viewed by 64

Abstract

In order to gain an insight into the stress state of drillstring in riserless drilling conditions with Casing while Drilling (CwD) technology, a stochastic and nonlinear dynamic model of the drillstring under the excitation of the environmental load is established based on Hamilton [...] Read more.

In order to gain an insight into the stress state of drillstring in riserless drilling conditions with Casing while Drilling (CwD) technology, a stochastic and nonlinear dynamic model of the drillstring under the excitation of the environmental load is established based on Hamilton principle and finite deformation theory. The distribution of tensile stress, bending stress, and effective stress along the axial direction of drillstring that is exposed to the ambient environment is emphasized, the influence of wall thickness and material of the drillpipe on the stress state of drillstring is also discussed. The numerical results show that significant fluctuations in cross-sectional stress occur during the riserless drilling process, particularly under varying hydrodynamic loads; the tensile stress and effective stress are larger on landing string and the maximum values of these stresses occur at the connection point of the landing string and casing string; the bending stress is larger on casing string and the maximum value occurs near the sea floor; and increasing the wall thickness and selecting the low-density material can help to reduce the stress of the drillstring. It can be concluded from the numerical results that during the CwD riserless drilling process, the effective stress on the cross section of drillstring is mainly determined by the tensile stress and the contribution of bending stress is comparably small, and the dangerous cross section of the drillstring is located at the connection point of landing string and casing string. The proposed dynamic model offers theoretical insights that can inform drillstring design and vibration mitigation strategies in CwD operations. Full article

(This article belongs to the Special Issue Numerical Modeling of Fluid-Structure Interactions in Ocean Engineering)

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49 pages, 4782 KiB

Open AccessReview

Key Parameters for Design Analysis and Optimization of Dynamic Inter-Array Power Cable Configurations in Floating Offshore Wind Farms

by Anja Schnepf and Ove Tobias Gudmestad

J. Mar. Sci. Eng. 2025, 13(5), 875; https://doi.org/10.3390/jmse13050875 (registering DOI) - 28 Apr 2025

Viewed by 45

Abstract

Power cables transmit electricity from offshore wind turbines (OWTs) to consumers. The configuration, design, and optimization of power cables for floating offshore wind turbines (FOWTs) are subject to various objectives, variables, and constraints. These components are outlined, and existing research gaps that need [...] Read more.

Power cables transmit electricity from offshore wind turbines (OWTs) to consumers. The configuration, design, and optimization of power cables for floating offshore wind turbines (FOWTs) are subject to various objectives, variables, and constraints. These components are outlined, and existing research gaps that need to be addressed for a more sustainable and robust design for future developments are highlighted. The main aim of power cable configuration design is to optimize performance and minimize costs. This can be achieved through thoughtful consideration of variables like power cable selection, configuration design, and the integration of specialized components and ancillaries. An extensive overview of constraints for power cable configuration design is provided, and the most important ones are identified. The local conditions determine which constraints are of key importance in optimization. Environmental factors like wind, waves, and especially currents significantly influence design processes, introducing uncertainties when comprehensive data are lacking. Marine growth posed a significant challenge in prior FOWT projects and must be considered carefully. Considering the potential impact of climate change is crucial, especially for extreme weather events. Early integration of environmental considerations and assessment of effects on socio-economic impacts is essential for a successful project. The power cable response is also influenced by its inherent limitations, including tension and compression thresholds, curvature constraints, and the necessary minimum fatigue life. A flowchart is provided to aid in choosing variables and constraints in the design and optimization processes. Full article

(This article belongs to the Special Issue Advanced Research in Flexible Riser and Pipelines)

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15 pages, 3729 KiB

Open AccessArticle

Adaptive Responses in Byssal Growth and Shedding: Insights from Pteria penguin Under Thread Trimming and Non-Trimming Conditions

by Hebert Ely Vasquez, Shangkun Wei, Guoliang Yang, Lingfeng Wang, Peixuan Yu, Mingyue Dong, Chao Yuan and Xing Zheng

J. Mar. Sci. Eng. 2025, 13(5), 874; https://doi.org/10.3390/jmse13050874 (registering DOI) - 28 Apr 2025

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Abstract

Bivalves use byssal threads for attachment and locomotion, periodically shedding and regenerating them. In the winged pearl oyster Pteria penguin—known for its strong byssus and its role in the pearl industry—shedding may occur when the byssal stalk reaches a critical size, although [...] Read more.

Bivalves use byssal threads for attachment and locomotion, periodically shedding and regenerating them. In the winged pearl oyster Pteria penguin—known for its strong byssus and its role in the pearl industry—shedding may occur when the byssal stalk reaches a critical size, although the underlying mechanism remains unclear. This study investigated whether artificial manipulation of the byssus (via trimming) could stimulate thread production and promote shedding in adult P. penguin from two size groups. Byssal threads attached to the substrate were trimmed every 3–5 days over a 30-day period and compared to untrimmed controls. Oysters with trimmed byssus produced significantly more threads, with smaller individuals outperforming larger ones in both thread count and byssal stalk diameter. Moreover, small oysters exhibited a higher frequency of complete byssal shedding. These findings suggest that trimming stimulates thread production and accelerates stalk thickening, potentially triggering shedding due to spatial constraints at the attachment site. This response appears to reflect an adaptive mechanism for maintaining effective attachment and may help explain how mechanical or environmental cues influence byssal dynamics. Understanding this process offers new insight into the behavioral and physiological plasticity of P. penguin, with potential applications in pearl oyster management and aquaculture. Full article

(This article belongs to the Special Issue Selection of Deep-Sea Aquaculture Species and Development of Supporting Technologies and Equipment)

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21 pages, 15447 KiB

Open AccessArticle

Optimization Design of Lazy-Wave Dynamic Cable Configuration Based on Machine Learning

by Xudong Zhao, Qingfen Ma, Jingru Li, Zhongye Wu, Hui Lu and Yang Xiong

J. Mar. Sci. Eng. 2025, 13(5), 873; https://doi.org/10.3390/jmse13050873 (registering DOI) - 27 Apr 2025

Viewed by 143

Abstract

The safe and efficient design of dynamic submarine cables is critical for the reliability of floating offshore wind turbines, yet traditional time-domain simulation-based optimization approaches are computationally intensive and time consuming. To address this challenge, this study proposes a closed-loop optimization framework that [...] Read more.

The safe and efficient design of dynamic submarine cables is critical for the reliability of floating offshore wind turbines, yet traditional time-domain simulation-based optimization approaches are computationally intensive and time consuming. To address this challenge, this study proposes a closed-loop optimization framework that couples machine learning with intelligent optimization algorithms for a dynamic cable configuration design. A high-fidelity surrogate model based on a backpropagation (BP) neural network was trained to accurately predict cable dynamic responses. Three optimization algorithms—Particle Swarm Optimization (PSO), Ivy Optimization (IVY), and Tornado Optimization (TOC)—were evaluated for their effectiveness in optimizing the arrangement of buoyancy and weight blocks. The TOC algorithm exhibited superior accuracy and convergence stability. Optimization results show an 18.3% reduction in maximum curvature while maintaining allowable effective tension limits. This approach significantly enhances optimization efficiency and provides a viable strategy for the intelligent design of dynamic cable systems. Future work will incorporate platform motions induced by wind turbine operation and explore multi-objective optimization schemes to further improve cable performance. Full article

(This article belongs to the Section Ocean Engineering)

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24 pages, 3015 KiB

Open AccessArticle

Toward Smart and Sustainable Port Operations: A Blue Ocean Strategy Approach for the Spanish Port System

by Nicoletta González-Cancelas, Juan José Guil López, Javier Vaca-Cabrero and Alberto Camarero-Orive

J. Mar. Sci. Eng. 2025, 13(5), 872; https://doi.org/10.3390/jmse13050872 (registering DOI) - 27 Apr 2025

Viewed by 76

Abstract

The digital transformation of the maritime sector, driven by Industry 4.0, is reshaping port operations toward smarter and more sustainable models. This paper analyzed the implementation of Port 4.0 technologies in the Spanish port system through the lens of the Blue Ocean Strategy. [...] Read more.

The digital transformation of the maritime sector, driven by Industry 4.0, is reshaping port operations toward smarter and more sustainable models. This paper analyzed the implementation of Port 4.0 technologies in the Spanish port system through the lens of the Blue Ocean Strategy. By redefining competitive boundaries and applying tools such as the Four Actions Framework and value innovation curves, the study proposes a new strategic vision where ports collaborate rather than compete. Key enabling technologies (such as Big Data, IoT, AI, and Blockchain) were assessed for their capacity to optimize energy use, reduce emissions, and enhance operational efficiency. The findings highlight the potential for a unified, data-driven port ecosystem that creates a new uncontested market space for Spanish ports while promoting environmental and economic sustainability. Full article

(This article belongs to the Special Issue Sustainable and Efficient Maritime Operations)

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21 pages, 12072 KiB

Open AccessArticle

Research on the Optimal Design of the Anti-Collision Structure of Floating Docks Based on Numerical Simulation

by Guo Wang, Yin You, Jingqiao Liu and Kai Li

J. Mar. Sci. Eng. 2025, 13(5), 871; https://doi.org/10.3390/jmse13050871 (registering DOI) - 27 Apr 2025

Viewed by 133

Abstract

Aiming to solve the problem of collisions that may occur with ships during the operation of the floating dock, which may lead to functional failure or even destruction of the dock, a new collision avoidance device has been researched and designed. Through simulation [...] Read more.

Aiming to solve the problem of collisions that may occur with ships during the operation of the floating dock, which may lead to functional failure or even destruction of the dock, a new collision avoidance device has been researched and designed. Through simulation analysis, the structural response of different collision speeds, different contact areas, and different structural forms of collision avoidance structures under typical working conditions was studied, and the basic law of buffering performance of in-dock collision avoidance devices for floating docks was derived, on the basis of which a new type of in-dock collision avoidance device for floating docks was designed. This study is important to ensure the operational safety and functionality of the floating dock. It can also provide a useful reference for the design of other ship collision avoidance structures. Full article

(This article belongs to the Section Ocean Engineering)

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18 pages, 4298 KiB

Open AccessArticle

Multi-Objective Path Optimization Method for Maritime UAVs Equipped with Inertial Navigation Systems

by Zhao Li, Weihao Ma and Haixiang Pang

J. Mar. Sci. Eng. 2025, 13(5), 870; https://doi.org/10.3390/jmse13050870 (registering DOI) - 27 Apr 2025

Viewed by 116

Abstract

Maritime unmanned aerial vehicles (UAVs) equipped with inertial navigation systems (INS) are prone to error accumulation, which can lead to excessive positioning errors and hinder their ability to perform long distance missions. To address this issue, this study first constructs a directed graph [...] Read more.

Maritime unmanned aerial vehicles (UAVs) equipped with inertial navigation systems (INS) are prone to error accumulation, which can lead to excessive positioning errors and hinder their ability to perform long distance missions. To address this issue, this study first constructs a directed graph network for a flight area based on start and end points as well as error correction points. A multi-objective route planning model is then developed for a UAV, aiming to minimize both the flight distance and the number of positioning corrections. Considering the UAV’s turning radius, a trajectory length calculation model based on 3D Dubins curves is designed. Subsequently, a forward labeling-based multi-objective path planning algorithm is proposed to develop an optimization model. Experimental results demonstrate that the proposed method can effectively constrain the UAV’s horizontal and vertical positioning errors within 2.5 m, while optimally balancing flight distance and positioning accuracy to ensure the successful execution of long-range maritime UAV missions. The comparative results demonstrate that, while satisfying the positioning error requirements, our proposed method achieves a reduction of over 1.5% in total flight distance for maritime UAVs compared to the NSGA-II algorithm. Full article

(This article belongs to the Section Ocean Engineering)

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11 pages, 4267 KiB

Open AccessArticle

Compression of Marine Environmental Data Using Convolutional Attention Autoencoder

by Xuehai Sun, Peiyu Wang, Yanxia Zhou, Kedi Wu, Limin Huang and Xuewen Ma

J. Mar. Sci. Eng. 2025, 13(5), 869; https://doi.org/10.3390/jmse13050869 (registering DOI) - 27 Apr 2025

Viewed by 97

Abstract

Ocean temperature data is fundamental to the study of ocean dynamics and climate change, and its efficient compression and storage are critical for large-scale data analysis and transmission. However, traditional compression methods based on Fourier transform struggle to balance compression ratio and fidelity [...] Read more.

Ocean temperature data is fundamental to the study of ocean dynamics and climate change, and its efficient compression and storage are critical for large-scale data analysis and transmission. However, traditional compression methods based on Fourier transform struggle to balance compression ratio and fidelity when confronted with the complex characteristics of marine environments. This study proposes a convolutional attention autoencoder (CAAE) to compress and reconstruct three-dimensional temperature fields and evaluates its performance across different depths and compression ratios. The experimental results indicate that although reconstruction error slightly increases with higher compression ratios, the proposed model achieves near-perfect compression and reconstruction of marine environmental data, performing robustly across various depths and spatial locations. This work offers a viable solution for the efficient and accurate compression of three-dimensional ocean data and provides valuable insights for the management of large-scale marine datasets. Full article

(This article belongs to the Section Physical Oceanography)

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21 pages, 5992 KiB

Open AccessArticle

A Parametric Study on the Effect of Blade Configuration in a Double-Stage Savonius Hydrokinetic Turbine

by Xiang Ying Tham, Cheng Yee Ng, Muk Chen Ong and Novi Fairindah Tingkas

J. Mar. Sci. Eng. 2025, 13(5), 868; https://doi.org/10.3390/jmse13050868 (registering DOI) - 27 Apr 2025

Viewed by 127

Abstract

Ocean energy represents a promising resource for renewable energy generation. Hydrokinetic turbines (HKTs) provide a sustainable method to extract energy from ocean currents. However, turbine efficiency remains limited, particularly in marine environments with low flow velocities. A parametric evaluation of blade configurations is [...] Read more.

Ocean energy represents a promising resource for renewable energy generation. Hydrokinetic turbines (HKTs) provide a sustainable method to extract energy from ocean currents. However, turbine efficiency remains limited, particularly in marine environments with low flow velocities. A parametric evaluation of blade configurations is conducted in this study to assess their effect on the power and torque performance of a double-stage drag-based Savonius HKT. Numerical simulations are conducted using the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations with the k-ω SST turbulence model. The numerical model is validated against published data, and analyses on mesh density, domain size, and time step are performed to ensure accuracy. Three blade configurations—(0°, 0°), (0°, 45°), and (0°, 90°) are evaluated under flow velocities of 0.6 m/s, 0.8 m/s, and 1.0 m/s. Results indicate that blade configuration significantly affects turbine performance. The (0°, 0°) configuration performs best at high flow velocity (1.0 m/s), while the (0°, 45°) setup achieves the highest efficiency at 0.6 m/s. The (0°, 90°) configuration performs the least effectively across all conditions. A similar performance trend is observed for the torque coefficient. This study recommends selecting blade configurations based on flow velocity, providing design guidance for double-stage HKTs operating in varying marine conditions. Full article

(This article belongs to the Section Ocean Engineering)

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21 pages, 13125 KiB

Open AccessArticle

Hypodontolaimus minus sp. nov. and Bolbolaimus distalamphidus sp. nov., Nematodes from the Yellow Sea, Including Phylogenetic Analyses Within Chromadoridae and Microlaimoidea

by Zhiyu Meng, Huixin Liang and Chunming Wang

J. Mar. Sci. Eng. 2025, 13(5), 867; https://doi.org/10.3390/jmse13050867 (registering DOI) - 27 Apr 2025

Viewed by 129

Abstract

Two new species from the Yellow Sea, Hypodontolaimus minus sp. nov. and Bolbolaimus distalamphidus sp. nov., are described in this study. Hypodontolaimus minus sp. nov. is characterized by a relatively small body length, a cuticle with two longitudinal lateral differentiations connected with transverse [...] Read more.

Two new species from the Yellow Sea, Hypodontolaimus minus sp. nov. and Bolbolaimus distalamphidus sp. nov., are described in this study. Hypodontolaimus minus sp. nov. is characterized by a relatively small body length, a cuticle with two longitudinal lateral differentiations connected with transverse bars, four files of sublateral somatic setae, a pharynx with an anterior and posterior bulb, L-shaped spicules, a slightly swollen proximal end, a distal end tapered with a posterior pointed hook, and a gubernaculum with dorsal caudal apophysis. Bolbolaimus distalamphidus sp. nov. is characterized by a relatively small body size, a strongly annulated cuticle, six short outer labial sensilla and four long cephalic setae, an amphideal fovea unispiral oval that is far from the anterior end, slightly curved spicules, gubernaculum with anterior-pointed apophysis, and a conical tail. Phylogenetic analyses within the family Chromadoridae and the superfamily Microlaimoidea based on combined rDNA sequences confirmed the placement of Hypodontolaimus minus sp. nov. and Bolbolaimus distalamphidus sp. nov. The subfamily of Chromadorinae is shown as a monophyletic clade, the genera of subfamily Hypodontolaiminae are shown as a paraphyletic group, and the genus of Ptycholaimellus shows high intraspecific diversity. The placement of genera Aponema and Molgolaimus within the superfamily Microlaimoidea is discussed based on combined rDNA sequences. Full article

(This article belongs to the Section Marine Biology)

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16 pages, 4631 KiB

Open AccessArticle

Genetic Differentiation in Red and Green Noctiluca scintillans in Jakarta Bay, Indonesia

by Muhammad Izzat Nugraha, Goh Nishitani, Akira Ishikawa, Sutanto Hadi, Waka Sato-Okoshi and Beginer Subhan

J. Mar. Sci. Eng. 2025, 13(5), 866; https://doi.org/10.3390/jmse13050866 (registering DOI) - 26 Apr 2025

Viewed by 213

Abstract

Marine dinoflagellate Noctiluca scintillans occurs in two forms, red and green, that overlap in distribution across the Arabian Sea and Southeast Asian coastal waters, particularly in Indonesia. However, limited genetic data on Indonesian N. scintillans cast uncertainty on their taxonomic status. In this [...] Read more.

Marine dinoflagellate Noctiluca scintillans occurs in two forms, red and green, that overlap in distribution across the Arabian Sea and Southeast Asian coastal waters, particularly in Indonesia. However, limited genetic data on Indonesian N. scintillans cast uncertainty on their taxonomic status. In this study, we introduce the first 28S PCR primer set specifically designed for Noctiluca to enable sequence analysis. The Indonesian red-type N. scintillans (RNS) sequences show considerable divergence from other documented populations, suggesting a potentially adapted population in Jakarta Bay. Similarly, the RNS in Indonesia differ genetically from co-occurring green-type N. scintillans (GNS). Morphological differences were also observed between Indonesian and Japanese RNS, with Indonesian cells exhibiting a smaller size and rougher surface, in contrast to the larger size and smoother surface observed in Japanese specimens. Full article

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29 pages, 16065 KiB

Open AccessArticle

Optimization of Adaptive Observation Strategies for Multi-AUVs in Complex Marine Environments Using Deep Reinforcement Learning

by Jingjing Zhang, Weidong Zhou, Xiong Deng, Shuo Yang, Chunwang Yang and Hongliang Yin

J. Mar. Sci. Eng. 2025, 13(5), 865; https://doi.org/10.3390/jmse13050865 (registering DOI) - 26 Apr 2025

Viewed by 87

Abstract

This paper explores the application of Deep Reinforcement Learning (DRL) to optimize adaptive observation strategies for multi-AUV systems in complex marine environments. Traditional algorithms struggle with the strong coupling between environmental information and observation modeling, making it challenging to derive optimal strategies. To [...] Read more.

This paper explores the application of Deep Reinforcement Learning (DRL) to optimize adaptive observation strategies for multi-AUV systems in complex marine environments. Traditional algorithms struggle with the strong coupling between environmental information and observation modeling, making it challenging to derive optimal strategies. To address this, we designed a DRL framework based on the Dueling Double Deep Q-Network (D3QN), enabling AUVs to interact directly with the environment for more efficient 3D dynamic ocean observation. However, traditional D3QN faces slow convergence and weak action–decision correlation in partially observable, dynamic marine settings. To overcome these challenges, we integrate a Gated Recurrent Unit (GRU) into the D3QN, improving state-space prediction and accelerating reward convergence. This enhancement allows AUVs to optimize observations, leverage ocean currents, and navigate obstacles while minimizing energy consumption. Experimental results demonstrate that the proposed approach excels in safety, energy efficiency, and observation effectiveness. Additionally, experiments with three, five, and seven AUVs reveal that while increasing platform numbers enhances predictive accuracy, the benefits diminish with additional units. Full article

(This article belongs to the Special Issue Underwater Observation Technology in Marine Environment)

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31 pages, 10580 KiB

Open AccessArticle

An Exploratory Assessment of a Submarine Topographic Characteristic Index for Predicting Extreme Flow Velocities: A Case Study of Typhoon In−Fa in the Zhoushan Sea Area

by Fanjun Chen, Wankang Yang, Long Xiao, Xiaoliang Xia, Kaixuan Ding and Zhilin Sun

J. Mar. Sci. Eng. 2025, 13(5), 864; https://doi.org/10.3390/jmse13050864 (registering DOI) - 25 Apr 2025

Viewed by 98

Abstract

This study analyzes the 96 h flow velocity time series data from the Zhoushan Sea during Typhoon In−fa to investigate the conditions for extreme flow velocities. Through force analysis of the unit fluid and statistical analysis of topographic features, we identified the critical [...] Read more.

This study analyzes the 96 h flow velocity time series data from the Zhoushan Sea during Typhoon In−fa to investigate the conditions for extreme flow velocities. Through force analysis of the unit fluid and statistical analysis of topographic features, we identified the critical water depth, slope, and sea surface width for extreme flow velocities under ideal conditions as 15 m, 4.5°, and 2000 m, respectively. The Submarine Topographic Characteristic Index (STCI) is introduced for the first time in this study, revealing its significant impact on extreme flow velocities. Three types of “extreme velocity points”—associated with constant storm surge, astronomical tide, and typhoon storm surge—were defined, occurring over 85% of the time during typhoon events. These extreme velocity points were analyzed in relation to their topographic characteristics, including water depth, slope, and sea surface width. Simulations of Typhoon In−fa in the Zhoushan Sea area were used to construct the STCI model, resulting in the following weightings: water depth = 0.96, slope = 0.39, and sea surface width = 0.49. Typhoon In−fa occurred in 2021, exhibited a maximum wind speed of approximately 35 m/s, and played a key role in the hydrodynamic processes investigated in this study. Validation with Typhoons Muifa (2021) and Bebinca (2413) confirmed the model’s high consistency. The STCI model provides insight into the occurrence of extreme velocities, categorizing them according to tidal phase and typhoon influence. Preliminary findings indicate the model’s applicability under varying typhoon intensities, offering a robust tool for predicting extreme seabed flow velocities during typhoon events. Full article

(This article belongs to the Section Coastal Engineering)

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22 pages, 3096 KiB

Open AccessArticle

SDA-Mask R-CNN: An Advanced Seabed Feature Extraction Network for UUV

by Yao Xiao, Dongchen Dai, Hongjian Wang, Chengfeng Li and Shaozheng Song

J. Mar. Sci. Eng. 2025, 13(5), 863; https://doi.org/10.3390/jmse13050863 (registering DOI) - 25 Apr 2025

Viewed by 210

Abstract

This paper proposes a novel SDA-Mask R-CNN framework for precise seabed terrain edge feature extraction from Side-Scan Sonar (SSS) images to enhance Unmanned Underwater Vehicle (UUV) perception and navigation. The developed architecture addresses critical challenges in underwater image analysis, including low segmentation accuracy [...] Read more.

This paper proposes a novel SDA-Mask R-CNN framework for precise seabed terrain edge feature extraction from Side-Scan Sonar (SSS) images to enhance Unmanned Underwater Vehicle (UUV) perception and navigation. The developed architecture addresses critical challenges in underwater image analysis, including low segmentation accuracy and ambiguous edge delineation, through three principal innovations. First, we introduce a Structural Synergistic Group-Attention Residual Network (SSGAR-Net) that integrates group convolution with an enhanced convolutional block attention mechanism, complemented by a layer-skipping architecture for optimized information flow and redundancy verification for computational efficiency. Second, a Depth-Weighted Hierarchical Fusion Network (DWHF-Net) incorporates depthwise separable convolution to minimize computational complexity while preserving model performance, which is particularly effective for high-resolution SSS image processing. This module further employs a weighted pyramid architecture to achieve multi-scale feature fusion, significantly improving adaptability to diverse object scales in dynamic underwater environments. Third, an Adaptive Synergistic Mask Optimization (ASMO) strategy systematically enhances mask generation through classification head refinement, adaptive post-processing, and progressive training protocols. Comprehensive experiments demonstrate that our method achieves 0.695 (IoU) segmentation accuracy and 1.0 (AP) edge localization accuracy. The proposed framework shows notable superiority in preserving topological consistency of seabed features, offering a reliable technical framework for underwater navigation and seabed mapping in marine engineering applications. Full article

(This article belongs to the Section Ocean Engineering)

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28 pages, 37690 KiB

Open AccessArticle

by Jiao Qi, Siyuan Cao, Zhiyong Wang, Yankai Xu and Qiqi Zhang

J. Mar. Sci. Eng. 2025, 13(5), 862; https://doi.org/10.3390/jmse13050862 (registering DOI) - 25 Apr 2025

Viewed by 82

Abstract

Surface-related multiple suppression is a critical step in seismic data processing, while traditional adaptive matching subtraction methods often distort primaries, resulting in either the leakage of primaries or the residue of surface-related multiples. To address these challenges, we propose a field-parameter-guided semi-supervised learning [...] Read more.

Surface-related multiple suppression is a critical step in seismic data processing, while traditional adaptive matching subtraction methods often distort primaries, resulting in either the leakage of primaries or the residue of surface-related multiples. To address these challenges, we propose a field-parameter-guided semi-supervised learning (FPSSL) method to more effectively eliminate surface-related multiples. Field parameters refer to the time–space coordinate information derived from the seismic acquisition system, including offsets, trace spaces, and sampling intervals. These parameters reveal the relative positional relationships of seismic data in the time–space domain. The FPSSL framework comprises a supervised network module (SNM) and an unsupervised network module (USNM). The input and output data of the SNM are a small sample of full wavefield data and the weights of a polynomial function, respectively. A linear weighted sum method is employed to represent the SNM outputs (weights), the full wavefield data, and field parameters as a polynomial function of the primaries, which is matched with adaptive subtraction label data. The trained SNM generates preliminary estimates of the primaries and multiples with improved lateral continuity from full wavefield data, both of which are used as inputs to the USNM. The USNM is essentially an optimization operator that refines the underlying nonlinear mapping relationship between primaries and full wavefield data using the local wavefield feature loss function, thereby obtaining more accurate prediction results with respect to primaries. Examples from synthetic data and real marine data demonstrate that the FPSSL method surpasses the traditional L1-norm adaptive subtraction method in suppressing multiples, significantly reducing the leakage of primaries and the residuals of surface-related multiples in the estimated demultiple results. The effectiveness and efficiency of our proposed method are verified through two sets of synthetic data and one marine data example. Full article

(This article belongs to the Section Ocean Engineering)

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25 pages, 18408 KiB

Open AccessArticle

Surf and Swash Zone Dynamics from High-Frequency Observations at a Microtidal Low-Energy Dissipative Beach

by Dimitris Chatzistratis, Antonis E. Chatzipavlis, Isavela N. Monioudi, Adonis F. Velegrakis, Olympos P. Andreadis, Fotis Psarros and Ivan T. Petsimeris

J. Mar. Sci. Eng. 2025, 13(5), 861; https://doi.org/10.3390/jmse13050861 - 25 Apr 2025

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Abstract

This study examines the surf and swash zone dynamics of a microtidal, low-energy, dissipative beach in Kos Island, Greece, using high-frequency optical monitoring with a Beach Optical Monitoring System (BOMS) and in situ wave measurements during the winter period. Increased wave heights induced [...] Read more.

This study examines the surf and swash zone dynamics of a microtidal, low-energy, dissipative beach in Kos Island, Greece, using high-frequency optical monitoring with a Beach Optical Monitoring System (BOMS) and in situ wave measurements during the winter period. Increased wave heights induced the offshore migration of the wave-breaking zone with significant alongshore variability; however, no triggering of NOM (Net Offshore Movement) behavior was verified, while occasional rhythmic patterns were observed in the breaking location under moderate wave conditions. Shoreline dynamics showed transient erosional episodes coupled with elevated run-up excursions, yet the shoreline showed signs of recovery, suggesting a quasi-equilibrium state. Run-up energy spectra were consistently dominated by lower frequencies than those of incoming waves under both low- and high-energy conditions. This behavior is attributed to the nearshore sandbars acting as low-pass filters, dissipating high-frequency wave energy and allowing for lower-frequency motions to dominate run-up processes. A widely used empirical wave run-up predictor corresponded well with the video observations, confirming its applicability to low-energy dissipative beaches. These results underscore the role of submerged sandbars in regulating wave energy dissipation and stabilizing beach morphology under low-to-moderate wave conditions. Full article

(This article belongs to the Section Coastal Engineering)

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27 pages, 11158 KiB

Open AccessArticle

Design and Research of a Propulsion-Enabled Station-Keeping Anchoring System Compatible with Shallow-Sea Profiling Floats

by Chenyang Gao, Fuwu Ji, Qunhui Yang, Zhinan Mi and Fang Wang

J. Mar. Sci. Eng. 2025, 13(5), 860; https://doi.org/10.3390/jmse13050860 - 25 Apr 2025

Viewed by 69

Abstract

Profiling floats are important platforms for oceanic profile observations, yet they are prone to positional drift and grounding when deployed in shallow-sea environments. In order to address these issues, an aluminum alloy-based propulsion-enabled station-keeping anchoring system (PESKAS) is designed in this paper. The [...] Read more.

Profiling floats are important platforms for oceanic profile observations, yet they are prone to positional drift and grounding when deployed in shallow-sea environments. In order to address these issues, an aluminum alloy-based propulsion-enabled station-keeping anchoring system (PESKAS) is designed in this paper. The PESKAS comprises anchor wings, thrusters, a steering connector, support frames, and an upper connection flange, which allows easy installation to the bottom of conventional profiling floats. Three anchor wings, with a cone angle of 40° and a length of 0.12 m, enable the attached profiling float to anchor to the seabed under ocean currents of up to 0.5 m/s when fully penetrating the sediment. Numerical simulation results show that achieving full penetration into clay, clayey silt, and silty sand requires thrust forces of 80–100 N, 100–120 N, and 160 N, respectively. To achieve full sediment penetration, the PESKAS employs a redundant quadruple-thruster configuration (total thrust 200 N) with an effective actuation duration of approximately 1 s. It ascends from the seabed via a thruster-generated upward force during the ascent of the profiling float, effectively avoiding grounding. Over a complete operational cycle (descent and ascent), the PESKAS consumes approximately 0.65–1.84 kJ of energy. Compared to the energy consumption of PROVOR profiling float motors (10.25 kJ) and sensors (8.33 kJ), the additional energy requirement for the PESKAS does not have a significant effect on the endurance of profiling floats. According to the results of the simulation experiment of the PESKAS, the system successfully achieves its design objectives of full penetration into and ascending from sediments. PESKAS is a cost-effective solution for the positional drift and grounding of profiling floats, which enables stable long-term profile observations in shallow-sea environments and has broad application prospects. Full article

(This article belongs to the Section Ocean Engineering)

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17 pages, 16712 KiB

Open AccessArticle

Large-Eddy Simulation of Flows Past an Isolated Lateral Semi-Circular Cavity

by Yiqing Gong, Yun Xu, Jingqiao Mao, Jie Dai, Lei He, Hao Zhang and Qianshun Xu

J. Mar. Sci. Eng. 2025, 13(5), 859; https://doi.org/10.3390/jmse13050859 (registering DOI) - 25 Apr 2025

Viewed by 90

Abstract

Lateral cavities along coastlines strongly influence sedimentary morphology and ecological processes by modifying local flow dynamics. This study employed high-resolution large-eddy simulation to investigate flow structures and momentum exchange mechanisms in a semi-circular lateral cavity driven by longshore currents. Model validation against experimental [...] Read more.

Lateral cavities along coastlines strongly influence sedimentary morphology and ecological processes by modifying local flow dynamics. This study employed high-resolution large-eddy simulation to investigate flow structures and momentum exchange mechanisms in a semi-circular lateral cavity driven by longshore currents. Model validation against experimental data confirmed the LES’s capability to capture both recirculating flow and turbulent structures accurately. The impact of Reynolds number was examined across three cases (

R e

= 12,000, 17,000, and 22,000). From

R e

= 12,000 to 17,000, a significant upstream shift of the primary vortex core occurred, accompanied by stronger shear layer turbulence and intensified secondary vortices. Between

R e

= 17,000 and 22,000, the flow features stabilized, indicating a transition toward quasi-equilibrium. These changes enhanced vertical momentum transfer and turbulence production within the cavity. Spectral analysis revealed dominant KH frequencies governing periodic momentum exchange and indicating a transition from viscosity-damped upstream turbulence to fully developed shedding downstream. Full article

(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards—3rd Edition)

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