Journal of Marine Science and Engineering

20 pages, 2749 KiB

Open AccessArticle

ROVs Utilized in Communication and Remote Control Integration Technologies for Smart Ocean Aquaculture Monitoring Systems

by Yen-Hsiang Liao, Chao-Feng Shih, Jia-Jhen Wu, Yu-Xiang Wu, Chun-Hsiang Yang and Chung-Cheng Chang

J. Mar. Sci. Eng. 2025, 13(7), 1225; https://doi.org/10.3390/jmse13071225 - 25 Jun 2025

Abstract

This study presents a new intelligent aquatic farming surveillance system that tackles real-time monitoring challenges in the industry. The main technical break-throughs of this system are evident in four key aspects: First, it achieves the smooth integration of remotely operated vehicles (ROVs), sensors, [...] Read more.

This study presents a new intelligent aquatic farming surveillance system that tackles real-time monitoring challenges in the industry. The main technical break-throughs of this system are evident in four key aspects: First, it achieves the smooth integration of remotely operated vehicles (ROVs), sensors, and real-time data transmission. Second, it uses a mobile communication architecture with buoy relay stations for distributed edge computing. This design supports future upgrades to Beyond 5G and satellite networks for deep-sea applications. Third, it features a multi-terminal control system that supports computers, smartphones, smartwatches, and centralized hubs, effectively enabling monitoring anytime, anywhere. Fourth, it incorporates a cost-effective modular design, utilizing commercial hardware and innovative system integration solutions, making it particularly suitable for farms with limited resources. The data indicates that the system’s 4G connection is both stable and reliable, demonstrating excellent performance in terms of data transmission success rates, control command response delays, and endurance. It has successfully processed 324,800 data transmission events, thoroughly validating its reliability in real-world production environments. This system integrates advanced technologies such as the Internet of Things, mobile communications, and multi-access control, which not only significantly enhance the precision oversight capabilities of marine farming but also feature a modular design that allows for future expansion into satellite communications. Notably, the system reduces operating costs while simultaneously improving aquaculture efficiency, offering a practical and intelligent solution for small farmers in resource-limited areas. Full article

(This article belongs to the Special Issue Design and Application of Underwater Vehicles)

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24 pages, 6478 KiB

Open AccessArticle

Numerical Simulation of Multi-Cluster Fracture Propagation in Marine Natural Gas Hydrate Reservoirs

by Lisha Liao, Youkeren An, Jinshan Wang, Yiqun Zhang, Lerui Liu, Meihua Chen, Yiming Gao and Jiayi Han

J. Mar. Sci. Eng. 2025, 13(7), 1224; https://doi.org/10.3390/jmse13071224 - 25 Jun 2025

Abstract

Natural gas hydrates (NGHs) are promising energy resources, although their marine exploitation is limited by low reservoir permeability and hydrate decomposition efficiency. Multi-cluster fracturing technology can enhance reservoir permeability, yet complex properties of hydrate sediments render the prediction of fracture behavior challenging. Therefore, [...] Read more.

Natural gas hydrates (NGHs) are promising energy resources, although their marine exploitation is limited by low reservoir permeability and hydrate decomposition efficiency. Multi-cluster fracturing technology can enhance reservoir permeability, yet complex properties of hydrate sediments render the prediction of fracture behavior challenging. Therefore, we developed a three-dimensional (3D) fluid–solid coupling model for hydraulic fracturing in NGH reservoirs based on cohesive elements to analyze the effects of sediment plasticity, hydrate saturation, fracturing fluid viscosity, and injection rate, as well as the stress interference mechanisms in multi-cluster simultaneous fracturing under different cluster spacings. Results show that selecting low-plastic reservoirs with high hydrate saturation (S_H > 50%) and adopting an optimal combination of fracturing fluid viscosity and injection rate can achieve the co-optimization of stimulated reservoir volume (SRV) and cross-layer risk. In multi-cluster fracturing, inter-fracture stress interference promotes the propagation of fractures along the fracture plane while suppressing it in the normal direction of the fracture plane, and this effect diminishes significantly till 9 m cluster spacing. This study provides valuable insights for the selection of optimal multi-cluster fracturing parameters for marine NGH reservoirs. Full article

(This article belongs to the Section Geological Oceanography)

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22 pages, 14459 KiB

Open AccessArticle

Experimental and Numerical Investigation of Localized Wind Effects from Terrain Variations at a Coastal Bridge Site

by Ziyong Lin, Dandan Xia, Yan Jiang, Zhiqun Yuan, Huaifeng Wang and Li Lin

J. Mar. Sci. Eng. 2025, 13(7), 1223; https://doi.org/10.3390/jmse13071223 - 25 Jun 2025

Abstract

Terrain conditions may significantly affect the near-ground-layer wind speed in coastal areas. In this research, wind tunnel tests and computational fluid dynamics (CFD) were performed to investigate the impact of topographic changes on the local wind field at coastal bridge sites. Considering the [...] Read more.

Terrain conditions may significantly affect the near-ground-layer wind speed in coastal areas. In this research, wind tunnel tests and computational fluid dynamics (CFD) were performed to investigate the impact of topographic changes on the local wind field at coastal bridge sites. Considering the geographic information system (GIS) information of an offshore bridge site, a 1:1000 topographic model was constructed to conduct tests in the wind tunnel lab under different wind directions. The influences of terrain conditions on localized wind characteristics such as the wind speed and wind attack angle under different test conditions were obtained. The results show that the wind angle varied between −6° and 6° under different conditions. To more comprehensively show the radius of influence on the local terrain, a CFD simulation was conducted. To verify the results of the wind tunnel tests, the SST k-ω model was compared and selected for simulation in this research. The influence radius of localized wind characteristics was determined by CFD simulation. The results indicate that the original topography showed “reverse amplification” on the leeward side, resulting in complex wake flows. These results may provide a reference for the design of wind-resistant structures such as bridges and offshore wind turbines in coastal areas. Full article

(This article belongs to the Topic Advances in Structural Wind-Resistant Analysis and Disaster Mitigation)

20 pages, 8370 KiB

Open AccessArticle

Lateral Performance of Monopile Foundations for Offshore Wind Turbines in Clay Soils: A Finite Element Investigation

by Yazeed A. Alsharedah

J. Mar. Sci. Eng. 2025, 13(7), 1222; https://doi.org/10.3390/jmse13071222 - 25 Jun 2025

Abstract

The continued upscaling of offshore wind turbines (OWTs) necessitates the development of foundation systems capable of sustaining increased lateral loads. As monopiles remain the most widely used foundation type for OWTs, a detailed investigation into their lateral behavior and soil flow under operational [...] Read more.

The continued upscaling of offshore wind turbines (OWTs) necessitates the development of foundation systems capable of sustaining increased lateral loads. As monopiles remain the most widely used foundation type for OWTs, a detailed investigation into their lateral behavior and soil flow under operational loading is warranted. This study utilized a nonlinear three-dimensional finite element model (FEM) to assess the lateral performance of monopiles supporting a 5 MW turbine in clayey soils. The results revealed that the lateral capacity and deformation behavior are governed primarily by soil shear strength and the monopile’s length-to-diameter ratio (L/D). In softer soils, increasing the L/D ratio led to notable enhancements in lateral resistance, up to fivefold, as well as significant reductions in pile head displacement and rotation. In contrasts, monopiles in stiff clay exhibited distinct failure patterns and less sensitivity to L/D variations. Soil deformation patterns at the ultimate state varied depending on stiffness, indicating distinct failure mechanisms in soft and stiff clays. These findings highlight the importance of incorporating realistic soil behavior and geometric influences in monopile foundation design for large OWTs. Full article

(This article belongs to the Special Issue Offshore Renewable Energy, Second Edition)

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25 pages, 8320 KiB

Open AccessArticle

Transient Flow Pattern and Vortex Evolution During the Startup Process of Novel Tulip-Type Hydraulic Turbines

by Shanshan Wei, Meng Wang and Chuang Ren

J. Mar. Sci. Eng. 2025, 13(7), 1221; https://doi.org/10.3390/jmse13071221 - 25 Jun 2025

Abstract

The Computational Fluid Dynamics (CFD) method is used to analyze the transient flow patterns and vortex evolution during the startup process of a novel tulip-type hydraulic turbine rotor. The model is validated with experimental results for the rotor’s torque and power coefficients. The [...] Read more.

The Computational Fluid Dynamics (CFD) method is used to analyze the transient flow patterns and vortex evolution during the startup process of a novel tulip-type hydraulic turbine rotor. The model is validated with experimental results for the rotor’s torque and power coefficients. The results show that the tulip-type rotor exhibits unique flow patterns compared to the traditional rotor. Vortices at different locations around the rotor influence the startup moment, either enhancing or suppressing it. Vortices downstream of the rotor form on the convex side of the blades, creating negative pressure that enhances startup and rotational performance. The expanded top design of the tulip-type rotor substantially improves startup performance through four distinct aspects: smoothly guiding incoming flow, dissipating gap vortices, clearing vortices to prevent blockage, and enhancing fluid-blade interaction to increase energy conversion efficiency. These characteristics of transient flow patterns and vortex evolution reveal the startup mechanism of the tulip-type rotor, providing a foundation for understanding the fluid dynamics of novel rotor designs and supporting the optimization of hydraulic turbine performance. Full article

(This article belongs to the Special Issue Hydraulic Modeling, Optimization and Intelligent Maintenance of Marine Fluid Machinery and Systems)

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22 pages, 8634 KiB

Open AccessArticle

Spatiotemporal Analysis of Sea-Surface pH in the Pacific Ocean Based on Interpretable Machine Learning

by Minlong Huang, Jin Qi, Can Zhang, Yuanyuan Wang, Yijun Chen, Jian Shao and Sensen Wu

J. Mar. Sci. Eng. 2025, 13(7), 1220; https://doi.org/10.3390/jmse13071220 - 25 Jun 2025

Abstract

Increasingly severe ocean acidification (OA) disrupts the balance of marine ecosystems. Seawater pH is a key indicator of OA but remains challenging to characterize due to sparse and limited in situ observations. In this study, we propose a spatiotemporal inversion method for surface [...] Read more.

Increasingly severe ocean acidification (OA) disrupts the balance of marine ecosystems. Seawater pH is a key indicator of OA but remains challenging to characterize due to sparse and limited in situ observations. In this study, we propose a spatiotemporal inversion method for surface pH based on interpretable machine learning. By applying carbonate system calculations, we construct an expanded pH observational dataset and obtain spatiotemporal distributions of pH and its influencing factors across the Pacific Ocean from 2003 to 2021. The interpretability analysis reveals that physical, biological, and optical factors contribute 53.9%, 23.9%, and 22.2%, respectively, to pH variability. Sea-surface temperature is the dominant driver, contributing 15.9% of all factors by regulating CO₂ solubility and biological activity. Particulate inorganic carbon (PIC) and particulate organic carbon (POC) show relative contributions of 12.6% and 9.4%, respectively, quantitatively reflecting the important roles of biogenic calcification and the biological carbon pump. Furthermore, the analysis focusing on the Niño 3.4 region reveals a potential pathway through which the ENSO disturbances may affect pH by influencing PIC and POC. Therefore, this study provides a data-driven approach to gain deeper insights into the spatiotemporal patterns of pH and its influencing factors. Full article

(This article belongs to the Section Chemical Oceanography)

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23 pages, 6040 KiB

Open AccessArticle

Stochastic Power Control Strategy for Hybrid Electric Propulsion Ships Using Markov Chain-Based Operational Data Augmentation

by Su Bin Choi, Soon Ho Hong and Sun Je Kim

J. Mar. Sci. Eng. 2025, 13(7), 1219; https://doi.org/10.3390/jmse13071219 - 25 Jun 2025

Abstract

Since power demand varies due to uncertain environmental conditions, a deterministic power control strategy for hybrid electric propulsion ships contains a limitation in securing robust performance. To overcome this limitation, this study applies a stochastic power control strategy based on the augmented operational [...] Read more.

Since power demand varies due to uncertain environmental conditions, a deterministic power control strategy for hybrid electric propulsion ships contains a limitation in securing robust performance. To overcome this limitation, this study applies a stochastic power control strategy based on the augmented operational dataset. This study generated 150 datasets and derived the optimal control strategy set using a dynamic programming algorithm. By synthesizing a set of optimal control strategies, we divided them into a total of 10 bins according to the battery state of charge (SOC) and implemented a probabilistic map for the power distribution ratio according to the demanded power in each bin. Additionally, the memory and SOC correction factor were utilized to prevent frequent changes in power control and ensure that the SOC remains stable. This strategy resulted in a 3% improvement in efficiency compared to the deterministic method. In addition, it can be implemented in a real-time strategy utilizing stochastic maps. Full article

(This article belongs to the Special Issue Advancements in Hybrid Power Systems for Marine Applications)

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16 pages, 8068 KiB

Open AccessArticle

Effects of Different Solid–Liquid Parameters on Flow Characteristics and Performance Output of Mineral Extraction Pumps: Analysis and Experimental Validation

by Shunjun Hong, Yuanwen Li, Xiaozhou Hu, Zihai Yang, Shaowei Lei, Pengyun Wei, Junhong Hu and Xingpeng Wang

J. Mar. Sci. Eng. 2025, 13(7), 1218; https://doi.org/10.3390/jmse13071218 - 25 Jun 2025

Abstract

It is essential to investigate the performance output and flow characteristics within deep-sea mineral extraction pumps using appropriate numerical calculation methods. In this study, by taking a deep-sea mineral extraction pump prototype as the subject, a small-scale mineral extraction pump model was constructed. [...] Read more.

It is essential to investigate the performance output and flow characteristics within deep-sea mineral extraction pumps using appropriate numerical calculation methods. In this study, by taking a deep-sea mineral extraction pump prototype as the subject, a small-scale mineral extraction pump model was constructed. Computational fluid dynamics methods, incorporating the SST

k - ω

turbulence model and the discrete phase model, were utilized to systematically investigate the pressure distribution, velocity field, streamline patterns, and performance characteristics of the mineral extraction pump under three operating conditions—low flow rate, rated flow rate, and high flow rate—while transporting mineral particles of three distinct sizes. The results demonstrated that the larger size of the mineral particles induced greater disturbance to the liquid phase. Under different flow conditions, the correlations between the particle size and both the head drop rate and power drop rate exhibited distinct characteristics. Experiments verified the rationality and precision of the numerical simulation approach. This study provides a methodological reference for analyzing the flow characteristics and performance output of deep-sea mineral extraction pumps. Full article

(This article belongs to the Special Issue Deep-Sea Mineral Resource Development Technology and Equipment)

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14 pages, 3850 KiB

Open AccessArticle

CFD Simulations of Basic Stepped-Hull Configurations in Planing Regime Using Star-CCM+ Software

by Konstantin I. Matveev

J. Mar. Sci. Eng. 2025, 13(7), 1217; https://doi.org/10.3390/jmse13071217 - 24 Jun 2025

Abstract

High-speed marine vehicles often employ stepped hulls with the purpose of ventilating bottom surfaces with air, thus reducing the hull’s water resistance. Due to the large number of possible geometrical variations for stepped hulls, numerical simulations can potentially make the process of designing [...] Read more.

High-speed marine vehicles often employ stepped hulls with the purpose of ventilating bottom surfaces with air, thus reducing the hull’s water resistance. Due to the large number of possible geometrical variations for stepped hulls, numerical simulations can potentially make the process of designing such hulls more effective. In this study, the computational fluid dynamics software Star-CCM+ (version 15.04.008) is applied to comparing the numerical results with the experimental hydrodynamic data available for prismatic hulls with one and two steps. Additionally, simulations are carried out for steps with different sweep angles, for three- and four-step hulls, and for a stepped hull in shallow water. Reasonable agreement with the test data was obtained, although some underestimation of drag and overprediction of air-ventilated zones were noted. In the studied conditions, increasing the forward sweep angle of a step, employing multi-step configurations, and operating in shallow water demonstrated further reductions in the wetted areas and the attainment of higher lift–drag ratios. Full article

(This article belongs to the Section Ocean Engineering)

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27 pages, 3462 KiB

Open AccessArticle

Visual-Based Position Estimation for Underwater Vehicles Using Tightly Coupled Hybrid Constrained Approach

by Tiedong Zhang, Shuoshuo Ding, Xun Yan, Yanze Lu, Dapeng Jiang, Xinjie Qiu and Yu Lu

J. Mar. Sci. Eng. 2025, 13(7), 1216; https://doi.org/10.3390/jmse13071216 - 24 Jun 2025

Abstract

A tightly coupled hybrid monocular visual SLAM system for unmanned underwater vehicles (UUVs) is introduced in this paper. Specifically, we propose a robust three-step hybrid tracking strategy. The feature-based method initially provides a rough pose estimate, then the direct method refines it, and [...] Read more.

A tightly coupled hybrid monocular visual SLAM system for unmanned underwater vehicles (UUVs) is introduced in this paper. Specifically, we propose a robust three-step hybrid tracking strategy. The feature-based method initially provides a rough pose estimate, then the direct method refines it, and finally, the refined results are used to reproject map points to improve the number of features tracked and stability. Furthermore, a tightly coupled visual hybrid optimization method is presented to address the inaccuracy of the back-end pose optimization. The selection of features for stable tracking is achieved through the integration of two distinct residuals: geometric reprojection error and photometric error. The efficacy of the proposed system is demonstrated through quantitative and qualitative analyses in both artificial and natural underwater environments, demonstrating excellent stable tracking and accurate localization results. Full article

(This article belongs to the Section Ocean Engineering)

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21 pages, 21979 KiB

Open AccessArticle

Modal Transportation Shifting from Road to Coastal-Waterways in the UK: Finding Optimal Capacity for Sustainable Freight Transport Through Swarming of Zero-Emission Barge Fleets

by Amin Nazemian, Evangelos Boulougouris and Myo Zin Aung

J. Mar. Sci. Eng. 2025, 13(7), 1215; https://doi.org/10.3390/jmse13071215 - 23 Jun 2025

Abstract

This paper examines the feasibility of transitioning road cargo to waterborne transport in the UK, aiming to reduce emissions and alleviate road congestion. Key objectives include (1) developing a modal shift technology to establish freight highways across the UK, (2) designing a small, [...] Read more.

This paper examines the feasibility of transitioning road cargo to waterborne transport in the UK, aiming to reduce emissions and alleviate road congestion. Key objectives include (1) developing a modal shift technology to establish freight highways across the UK, (2) designing a small, decarbonized barge vessel concept that complements the logistics framework, and (3) assessing the economic and environmental viability of a multimodal logistics network. Using discrete event simulation (DES), four transportation scenarios were analyzed to evaluate the efficiency and sustainability of integrating coastal and inland waterways into the logistics framework. Results indicate that waterborne transport is more cost-effective and environmentally sustainable than road transport. A sweeping design study was conducted to optimize time, cost, and emissions. This model was applied to a case study, providing insights into optimal pathways for transitioning to waterborne freight by finding the optimized number of TEUs. Consequently, our study identified 96 TEUs as the optimal capacity to initiate barge design, balancing cost, time, and emissions, while 126 TEUs emerged as the best option for scalability. Findings offer critical guidance for supporting the UK’s climate goals and governmental policies by advancing sustainable transportation solutions. Full article

(This article belongs to the Special Issue Green Shipping Corridors and GHG Emissions)

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27 pages, 14919 KiB

Open AccessArticle

A Super-Twisting Sliding-Mode Control Strategy for a Heaving Point Absorber Wave Energy Converter

by Zhongfeng Li, Lixian Wang, Lidong Wang, Xiaoping Liu, Zhongyi Wang and Lei Liu

J. Mar. Sci. Eng. 2025, 13(7), 1214; https://doi.org/10.3390/jmse13071214 - 23 Jun 2025

Abstract

This paper proposes a super-twisting sliding-mode control (STSMC) strategy to enhance the efficiency and stability of a heaving point absorber wave energy converter (PAWEC) system equipped with a permanent magnet synchronous generator (PMSG). In particular, the STSMC is designed to address both generator-side [...] Read more.

This paper proposes a super-twisting sliding-mode control (STSMC) strategy to enhance the efficiency and stability of a heaving point absorber wave energy converter (PAWEC) system equipped with a permanent magnet synchronous generator (PMSG). In particular, the STSMC is designed to address both generator-side and grid-side control challenges by ensuring precise regulation under varying wave conditions. A dynamical model of the PAWEC is developed to describe system responses, while the power take-off (PTO) mechanism is tailored to maintain consistent generator speed and efficient energy conversion. Lyapunov stability theory is employed to verify the stability of the proposed controller. Simulation studies and tests on a small-scale experimental setup with a 500 W PAWEC model under regular and irregular waves demonstrate that STSMC improves generator speed regulation and power output by more than 30% compared to field-oriented control (FOC), nonlinear adaptive backstepping (NAB), and first-order sliding-mode control (FOSMC). The proposed approach also manages grid-side total harmonic distortion (THD) effectively, keeping it below 5%. These results indicate that STSMC can substantially improve the dynamic performance and energy efficiency of wave energy systems. Full article

(This article belongs to the Section Ocean Engineering)

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30 pages, 13547 KiB

Open AccessArticle

A Measure–Correlate–Predict Approach for Transferring Wind Speeds from MERRA2 Reanalysis to Wind Turbine Hub Heights

by José A. Carta, Diana Moreno and Pedro Cabrera

J. Mar. Sci. Eng. 2025, 13(7), 1213; https://doi.org/10.3390/jmse13071213 - 23 Jun 2025

Abstract

Reanalysis datasets, such as MERRA2, are frequently used in wind resource assessments. However, their wind speed data are typically limited to fixed altitudes that differ from wind turbine hub heights, which introduces significant uncertainty in energy yield estimations. To address this challenge, we [...] Read more.

Reanalysis datasets, such as MERRA2, are frequently used in wind resource assessments. However, their wind speed data are typically limited to fixed altitudes that differ from wind turbine hub heights, which introduces significant uncertainty in energy yield estimations. To address this challenge, we propose a reproducible Measure–Correlate–Predict (MCP) framework that integrates Random Forest (RF) supervised learning to estimate hub-height wind speeds from MERRA2 data at 50 m. The method includes the fitting of 21 vertical wind profile models using data at 2 m, 10 m, and 50 m, with model selection based on the minimum mean square error. The approach was applied to seven wind-prone locations in the Canary Islands, selected for their strategic relevance in current or planned wind energy development. Results indicate that a three-parameter logarithmic wind profile achieved the best fit in 51.31% of cases, significantly outperforming traditional single-parameter models. The RF-based MCP predictions at different hub heights achieved RMSE metrics below 0.425 m/s across a 10-year period. These findings demonstrate the potential of combining physical modeling with machine learning to enhance wind speed extrapolation from reanalysis data and support informed wind energy planning in data-scarce regions. Full article

(This article belongs to the Section Coastal Engineering)

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3 pages, 171 KiB

Open AccessEditorial

Application of CFD Simulations to Marine Hydrodynamic Problems

by Peng Du and Abdellatif Ouahsine

J. Mar. Sci. Eng. 2025, 13(7), 1212; https://doi.org/10.3390/jmse13071212 - 23 Jun 2025

Abstract

Growing global energy demand and the increasing exploration of the ocean have brought about significant challenges and opportunities in the field of marine engineering and fluid mechanics [...] Full article

(This article belongs to the Special Issue Application of CFD Simulations to Marine Hydrodynamic Problems)

27 pages, 5732 KiB

Open AccessArticle

Impacts of Wind Assimilation on Error Correction of Forecasted Dynamic Loads from Wind, Wave, and Current for Offshore Wind Turbines

by Jing Zou, Shuai Yang, Xiaolei Liu, Hang Wang, Lu Liu, Xingsen Guo, Hong Zhang, Zhijin Qiu and Zhipeng Gai

J. Mar. Sci. Eng. 2025, 13(7), 1211; https://doi.org/10.3390/jmse13071211 - 23 Jun 2025

Abstract

In this study, a dynamic load forecasting model was developed for offshore wind turbines, based on the COAWST (Coupled Ocean-Atmosphere-Wave-Sediment Transport) model, the GRU (Gated Recurrent Unit) algorithm, and a data assimilation module. The model was able to forecast aerodynamic, wave, and current [...] Read more.

In this study, a dynamic load forecasting model was developed for offshore wind turbines, based on the COAWST (Coupled Ocean-Atmosphere-Wave-Sediment Transport) model, the GRU (Gated Recurrent Unit) algorithm, and a data assimilation module. The model was able to forecast aerodynamic, wave, and current loads acting on the turbines. Four groups of forecasting tests were conducted to evaluate the model’s performance under different strategies and to assess the impact of atmospheric assimilation on improving dynamic load forecasts. The wind turbines in Cangnan Offshore Wind Farm, located in the west of the East China Sea, were chosen as the study object. The results indicated that the model achieved high forecasting accuracy, with the RMSEs (root mean square errors) of 275.59 kN, 335.85 kN, and 313.51 N, for the aerodynamic, wave, and current loads. The errors were reduced by about 13%, 10.09%, and 6.7% when compared with the original COAWST model, and were also lower than the atmospheric and oceanic reanalysis data. Atmospheric data assimilation was demonstrated to reduce the forecasting RMSE of aerodynamic load by about 12%, and its error improvement was able to be combined with GRU-based error correction. Additionally, atmospheric assimilation mitigated the reduction in temporal variability caused by forecasting error correction, preventing a decrease in the standard deviation of aerodynamic load forecasts. However, atmospheric assimilation had minimal impacts on wave and current load forecasts, with the RMSEs increased by about 2.5% and 0.1%, and had almost the same performance in correlation coefficients and standard deviations. Full article

(This article belongs to the Section Coastal Engineering)

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26 pages, 9190 KiB

Open AccessArticle

Two-Objective Optimization of Tidal Array Micro-Sitting Accounting for Yaw Angle Effects

by Can Zhang, Yichi Zhang, Jisheng Zhang, Xiaoming Cheng, Xiangfeng Lin, Chengsheng Wu and Zihan Ding

J. Mar. Sci. Eng. 2025, 13(7), 1210; https://doi.org/10.3390/jmse13071210 - 22 Jun 2025

Abstract

Power output and economic cost are two critical factors influencing the layout of tidal stream turbine arrays. To identify the optimal configuration, this study establishes a two-objective optimization framework that simultaneously considers these factors. Both the spatial location and yaw angle of each [...] Read more.

Power output and economic cost are two critical factors influencing the layout of tidal stream turbine arrays. To identify the optimal configuration, this study establishes a two-objective optimization framework that simultaneously considers these factors. Both the spatial location and yaw angle of each turbine are optimized to enhance overall power output, while the total length of submarine cables, which is used to transmit electricity from the turbines to the onshore power station, is adopted as the metric for economic cost. The Huludao water area is selected as the study domain. A 12-turbine array is examined under varying weight coefficients to investigate the trade-off between maximizing power output and minimizing economic cost. The optimization results show that submarine cable length decreases linearly as its economic weight coefficient increases, while the array’s power output exhibits a stepwise decline. This indicates that, with carefully chosen weight coefficients, economic costs can be significantly reduced without a proportional sacrifice in power output. Furthermore, increasing the number of turbines connected by a single cable not only enhances power output but also reduces total cable length, thereby improving the overall profitability of the optimized array layout. Full article

(This article belongs to the Section Marine Energy)

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21 pages, 6037 KiB

Open AccessArticle

Storm-Induced Evolution on an Artificial Pocket Gravel Beach: A Numerical Study with XBeach-Gravel

by Hanna Miličević, Dalibor Carević, Damjan Bujak, Goran Lončar and Andrea Tadić

J. Mar. Sci. Eng. 2025, 13(7), 1209; https://doi.org/10.3390/jmse13071209 - 22 Jun 2025

Abstract

Coarse-grained beaches consisting of gravel, pebbles, and cobbles play a crucial role in coastal protection. On the Croatian Adriatic coast, there are artificial gravel pocket beaches created for recreational and protective purposes. However, these beaches are subject to constant morphological changes due to [...] Read more.

Coarse-grained beaches consisting of gravel, pebbles, and cobbles play a crucial role in coastal protection. On the Croatian Adriatic coast, there are artificial gravel pocket beaches created for recreational and protective purposes. However, these beaches are subject to constant morphological changes due to natural forces and human intervention. This study investigates the morphodynamics of artificial gravel pocket beaches, focusing on berm formation and crest build-up processes characteristic for low to moderate wave conditions. Despite mimicking natural formations, artificial beaches require regular maintenance due to sediment shifts dominantly caused by wave action and storm surges. Structure-from-Motion (SfM) photogrammetry and UAV-based surveys were used to monitor morphological changes on the artificial gravel pocket beach Ploče (City of Rijeka). The XBeach-Gravel model, originally adapted to simulate the effects of high-energy waves, was calibrated and validated to analyze low to moderate wave dynamics on gravel pocket beaches. The calibration includes adjustments to the inertia coefficient (ci), which influences sediment transport by shear stress at the bottom; the angle of repose (ϕ), which controls avalanching and influences sediment transport on sloping beds; and the bedload transport calibration coefficient (γ), which scales the transport rates linearly. By calibrating XBeach-G for low to moderate wave conditions, this research improves the accuracy of the model for the cases of morphological responses “berm formation” and “crest build-up”. Full article

(This article belongs to the Section Marine Hazards)

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28 pages, 7871 KiB

Open AccessArticle

Research on Reservoir Identification of Gas Hydrates with Well Logging Data Based on Machine Learning in Marine Areas: A Case Study from IODP Expedition 311

by Xudong Hu, Wangfeng Leng, Kun Xiao, Guo Song, Yiming Wei and Changchun Zou

J. Mar. Sci. Eng. 2025, 13(7), 1208; https://doi.org/10.3390/jmse13071208 - 21 Jun 2025

Abstract

Natural gas hydrates, with their efficient and clean energy characteristics, are deemed a significant pillar within the future energy sector, and their resource quantification and development have a profound impact on the transformation of global energy structure. However, how to accurately identify gas [...] Read more.

Natural gas hydrates, with their efficient and clean energy characteristics, are deemed a significant pillar within the future energy sector, and their resource quantification and development have a profound impact on the transformation of global energy structure. However, how to accurately identify gas hydrate reservoirs (GHRs) is currently a hot research topic. This study explores the logging identification method of marine GHRs based on machine learning (ML) according to the logging data of the International Ocean Drilling Program (IODP) Expedition 311. This article selects six ML methods, including Gaussian process classification (GPC), support vector machine (SVM), multilayer perceptron (MLP), random forest (RF), extreme gradient boosting (XGBoost), and logistic regression (LR). The internal relationship between logging data and hydrate reservoir is analyzed through six ML algorithms. The results show that the constructed ML model performs well in gas hydrate reservoir identification. Among them, RF has the highest accuracy, precision, recall, and harmonic mean of precision and recall (F1 score), all of which are above 0.90. With an area under curve (AUC) of nearly 1 for RF, it is confirmed that ML technology is effective in this area. Research has shown that ML provides an alternative method for quickly and efficiently identifying GHRs based on well logging data and also offers a scientific foundation and technical backup for the future prospecting and mining of natural gas hydrates. Full article

(This article belongs to the Special Issue Advances in Marine Gas Hydrate Exploration and Discovery—2nd Edition)

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16 pages, 2211 KiB

Open AccessArticle

Impact of Convective Heat Transfer on Circular Tube Components in Polar Ships Within Ice-Covered Regions

by Houli Liu, Haiming Wen, Jing Cao, Xueyang Han, Chenyang Liu and Dayong Zhang

J. Mar. Sci. Eng. 2025, 13(7), 1207; https://doi.org/10.3390/jmse13071207 - 21 Jun 2025

Abstract

The upper facilities of polar marine equipment face severe freezing risks in ice-covered regions, necessitating energy-efficient electric heat tracing design. Existing models neglect coupled environmental factors (temperature–wind–humidity), leading to the overestimation of heating power. In this paper, experiment and CFD simulation are used [...] Read more.

The upper facilities of polar marine equipment face severe freezing risks in ice-covered regions, necessitating energy-efficient electric heat tracing design. Existing models neglect coupled environmental factors (temperature–wind–humidity), leading to the overestimation of heating power. In this paper, experiment and CFD simulation are used to study the change of convective heat transfer coefficients of electric tracing circular tube components under the polar coupling environmental conditions of wind speed of 0~8 m/s, temperature of −40~0 °C, and air relative humidity of 10~95%, and the corresponding mathematical prediction model is established. The results show that increasing the wind speed and relative humidity will both increase the convective heat transfer coefficient of the circular tube, while the temperature is inversely proportional to the convective heat transfer coefficient of the circular tube. The convective heat transfer coefficient shows an average growth rate of only 2.8–3.8% as the temperature decreases from −10 °C to −40 °C, which is significantly lower than the effects of wind speed (average growth rate 59–50%) and humidity (average growth rate 7.5–12.7%). When the wind speed exceeds 2 m/s, the growth rate of humidity’s effect on the coefficient increases from 17.82% to 33.96%. Mathematical prediction models can provide certain references for the calculation and design of reasonable heating amounts for anti-icing and de-icing of polar equipment’s circular tube components under ice-covered regions. Full article

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

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Journal of Marine Science and Engineering

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