Journal of Marine Science and Engineering

22 pages, 7153 KiB

Open AccessArticle

Using 14 Years of Satellite Data to Describe the Hydrodynamic Circulation of the Patras and Corinth Gulfs

by Basile Caterina and Aurélia Hubert-Ferrari

J. Mar. Sci. Eng. 2025, 13(3), 623; https://doi.org/10.3390/jmse13030623 - 20 Mar 2025

Viewed by 720

In the absence of in situ data, remote sensing becomes one of the most effective methods for analyzing the hydrodynamics of a basin. In the Gulf of Corinth, the lack of in situ information was addressed using 14 years of satellite data from [...] Read more.

In the absence of in situ data, remote sensing becomes one of the most effective methods for analyzing the hydrodynamics of a basin. In the Gulf of Corinth, the lack of in situ information was addressed using 14 years of satellite data from the Copernicus database to investigate the water circulation dynamics of the Gulfs of Patras and Corinth. The combination of satellite observations and Data Interpolating Empirical Orthogonal Function (DINEOF) methods produced comprehensive maps detailing the hydrodynamic patterns in both gulfs. Despite the paucity of some parts of the datasets, the remaining data revealed key hydrodynamic features through their observations. From the western Patras Gulf to the eastern Corinth Gulf, gyres were the dominant features. The Patras Gulf is primarily characterized by a cyclonic gyre, while the Rio–Antirio Strait, which connects the two gulfs, exhibits unique dynamics due to internal wave activity and upwelling events. Currents generated near the strait flow toward the Corinth Gulf, where they are mostly trapped in an anticyclonic gyre near Itea Bay and a cyclonic gyre near Antikyra Bay. Our analysis highlights the unique dynamics of enclosed gulfs connected to the open sea via a strait. In this case, the Corinth Gulf acts as a smaller-scale analog to the Mediterranean Sea, offering insights into similar hydrodynamic behaviors. The updated hydrodynamic data also improve our understanding of sediment transport pathways and the chlorophyll distribution under present and past conditions. Full article

(This article belongs to the Section Physical Oceanography)

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15 pages, 10887 KiB

Open AccessArticle

Geomorphometric Analysis of Submarine Mud Volcanoes: Variability, Evolutionary Trends, and Geohazard Implications

by Simone Napoli, Daniele Spatola, Daniele Casalbore and Francesco Latino Chiocci

J. Mar. Sci. Eng. 2025, 13(3), 622; https://doi.org/10.3390/jmse13030622 - 20 Mar 2025

Viewed by 231

Abstract

The systematic morphometric analyses of submarine mud volcanoes are widespread yet still poorly understood geological features. Our study reveals that submarine mud volcanoes show significant variability in size and geometry, independent of water depth. Specifically, the mean height-to-radius (H/R) ratio is ~0.14 ± [...] Read more.

The systematic morphometric analyses of submarine mud volcanoes are widespread yet still poorly understood geological features. Our study reveals that submarine mud volcanoes show significant variability in size and geometry, independent of water depth. Specifically, the mean height-to-radius (H/R) ratio is ~0.14 ± 0.08 (±1σ). This study focuses primarily on submarine mud volcanoes in the Mediterranean, which account for approximately 58% of the dataset and include structures reaching heights of up to ~500 m with mean diameters of up to 8000 m. These edifices display a range of basal geometries, from sub-elliptical (e.g., North Alex, off the coast of Egypt) to super-elliptical (e.g., Alberto da Ottaviano in the Mediterranean Ridge Accretionary Complex). A comparative analysis of morphometric parameters distinguishes mud cones from mud pies globally, with the latter generally lacking large examples (mean diameter >10 km). The results suggest distinct evolutionary pathways, beginning with small simple cones (~100 m³ in volume), analogous to arc volcanoes in other geological settings. This study integrates fundamental marine geology with applied geohazard considerations, serving as an initial step toward enhancing shared knowledge of submarine mud volcanoes. By improving the understanding of their formation, morphometric variability, and spatial distribution, this research supports better-informed decisions regarding submarine geohazards. Full article

(This article belongs to the Special Issue Technical Applications and Latest Discoveries in Seafloor Mapping)

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24 pages, 4334 KiB

Open AccessArticle

The Role of the Fishing Sector in the Blue Economy: Prioritization, Environmental Challenges, and Sustainable Strategies in Europe, with a Focus on Spain

by Nicoletta González-Cancelas, Javier Vaca-Cabrero and Alberto Camarero-Orive

J. Mar. Sci. Eng. 2025, 13(3), 621; https://doi.org/10.3390/jmse13030621 - 20 Mar 2025

Viewed by 335

Abstract

The fishing sector is a key component of the European Blue Economy, contributing to economic growth, food security, and employment. However, it faces sustainability challenges, including overfishing, biodiversity loss, and climate change impacts. This study uses decision tree modeling to assess the sector’s [...] Read more.

The fishing sector is a key component of the European Blue Economy, contributing to economic growth, food security, and employment. However, it faces sustainability challenges, including overfishing, biodiversity loss, and climate change impacts. This study uses decision tree modeling to assess the sector’s prioritization within the Blue Economy, comparing its economic and environmental footprint to other maritime industries. Using EU Fleet Register data, findings reveal disparities in fleet modernization and efficiency, with industrialized fleets in Spain, France, and Italy exhibiting higher tonnage and power, while artisanal fisheries in Greece and Portugal remain more vulnerable to economic and environmental shifts. The study highlights the sector’s economic relevance but also its exposure to regulatory constraints, emphasizing the need for modernization and stricter sustainability policies. The paper proposes technological innovation, enhanced regulations, and conservation-based management to align fisheries with Sustainable Development Goal 14, the EU Common Fisheries Policy, and the European Green Deal. These insights provide data-driven strategies for policymakers and industry stakeholders to ensure a more sustainable and resilient fishing sector. Full article

(This article belongs to the Special Issue The 10th Anniversary of Section “Marine Biology”—Recent Advances and Future Perspectives)

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21 pages, 7982 KiB

Open AccessArticle

Prediction of Fatigue Life at the Root Section of Offshore Single-Pile Wind Turbine Tower

by Xingguo Gao, Huihuang Ying, Lele Li, Zengliang Chang, Mei Kong and Xiaojie Tian

J. Mar. Sci. Eng. 2025, 13(3), 620; https://doi.org/10.3390/jmse13030620 - 20 Mar 2025

Viewed by 185

Abstract

This study presents a comprehensive investigation into multi-directional fatigue damage characteristics of fixed offshore wind turbine tower roots through comparative analysis using FAST (3.5.0) and Bladed (4.3) software platforms. The research methodology encompasses three principal phases: First, a stochastic wind field model was [...] Read more.

This study presents a comprehensive investigation into multi-directional fatigue damage characteristics of fixed offshore wind turbine tower roots through comparative analysis using FAST (3.5.0) and Bladed (4.3) software platforms. The research methodology encompasses three principal phases: First, a stochastic wind field model was developed through statistical analysis of historical wind speed measurements, achieving superior correlation (R² = 0.983) in goodness-of-fit tests. Subsequently, the rain flow counting technique was employed to characterize equivalent cyclic load spectra. Building upon these foundations, an integrated predictive fatigue life evaluation framework was formulated by synergistically combining S–N curve principles with Palmgren–Miner’s linear cumulative damage theory. The methodology was further validated through cross-platform verification with Bladed software, revealing only a 7.4% deviation in predicted fatigue lives between the two computational models, confirming the technical feasibility of the proposed simplified model. Full article

(This article belongs to the Special Issue Fatigue Performance and Ultimate Strength of Ships and Marine Structures)

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27 pages, 13847 KiB

Open AccessArticle

Scale Effects on Nominal Wake Fraction in Shallow Water: An Experimental and CFD Investigation

by Asif Raza, Qingsong Zeng and Wim Van Hoydonck

J. Mar. Sci. Eng. 2025, 13(3), 619; https://doi.org/10.3390/jmse13030619 - 20 Mar 2025

Viewed by 183

Abstract

The investigation of the wake field and nominal wake fraction in shallow water is critical for understanding ship hydrodynamics in confined environments. While extensive research has been conducted on deep water wake behavior, limited studies have addressed the effects of shallow water and [...] Read more.

The investigation of the wake field and nominal wake fraction in shallow water is critical for understanding ship hydrodynamics in confined environments. While extensive research has been conducted on deep water wake behavior, limited studies have addressed the effects of shallow water and scale on wake characteristics. This study systematically examines the influence of water depth and scale on wake field and nominal wake fraction through a combined approach of experimental model testing and computational fluid dynamics (CFD) simulations. A series of towing tank experiments were conducted in shallow water conditions using the Aframax hull form, and the results were validated by numerical simulations performed with the CFD solver STAR-CCM+. The findings highlight a significant impact on wake fraction due to scale effects, revealing nonlinear trends across different Reynolds numbers. Based on these observations, a predictive equation for nominal wake fraction in shallow water is proposed. The applicability of the equation was assessed by applying it to the KVLCC2 benchmark hull form, demonstrating its potential for use with other similar hull forms. These findings enhance the understanding of wake field dynamics in confined waters, enabling more precise ship design, improved performance predictions, and greater overall efficiency. Full article

(This article belongs to the Special Issue Hydrodynamic Research of Marine Structures (2nd Edition))

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20 pages, 6360 KiB

Open AccessArticle

Intelligent Detection of Oceanic Front in Offshore China Using EEFD-Net with Remote Sensing Data

by Ruijie Kong, Ze Liu, Yifei Wu, Yong Fang and Yuan Kong

J. Mar. Sci. Eng. 2025, 13(3), 618; https://doi.org/10.3390/jmse13030618 - 20 Mar 2025

Viewed by 247

Abstract

Oceanic fronts delineate the boundaries between distinct water masses within the ocean, typically marked by shifts in weather patterns and the generation of oceanic circulation. These fronts are identified in research on intelligent oceanic front detection primarily by their significant temperature gradients. The [...] Read more.

Oceanic fronts delineate the boundaries between distinct water masses within the ocean, typically marked by shifts in weather patterns and the generation of oceanic circulation. These fronts are identified in research on intelligent oceanic front detection primarily by their significant temperature gradients. The refined identification of oceanic fronts is of great significance to maritime material transportation and ecological environment protection. In view of the weak edge nature of oceanic fronts and the misdetection or missed detection of oceanic fronts by some deep learning methods, this paper proposes an oceanic front detection method based on the U-Net model that integrates Edge-Attention-Module and the Feature Pyramid Network Module (FPN-Module). We conduct detailed statistical analysis and change rate calculation of the oceanic front, and batch process to obtain preliminary high-quality annotation data, which improves efficiency and saves time. Then, we perform manual corrections to correct missed detections or false detections to ensure the accuracy of annotations. Approximately 4800 days of daily average sea temperature fusion data from CMEMS (Copernicus Marine Environment Monitoring Service) are used for analysis, and an Encoder-Edge-FPN-Decoder Network (EEFD-Net) structure is established to enhance the model’s accuracy in detecting the edges of oceanic fronts. Experimental results demonstrate that the improved model’s front identification capability is in strong agreement with fronts segmented and annotated using the threshold method, with IoU and weighted Dice scores reaching 98.81% and 95.56%, respectively. The model can accurately locate the position of oceanic fronts, with superior detection of weak fronts compared to other network models, capturing smaller fronts more precisely and exhibiting stronger connectivity. Full article

(This article belongs to the Section Physical Oceanography)

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26 pages, 13139 KiB

Open AccessArticle

Intelligent Computerized Video Analysis for Automated Data Extraction in Wave Structure Interaction; A Wave Basin Case Study

by Samuel Hugh Wolrige, Damon Howe and Hamed Majidiyan

J. Mar. Sci. Eng. 2025, 13(3), 617; https://doi.org/10.3390/jmse13030617 - 20 Mar 2025

Viewed by 359

Abstract

Despite advancements in direct sensing technologies, accurately capturing complex wave–structure interactions remain a significant challenge in ship and ocean engineering. Ensuring the safety and reliability of floating structures requires precise monitoring of dynamic water interactions, particularly in extreme sea conditions. Recent developments in [...] Read more.

Despite advancements in direct sensing technologies, accurately capturing complex wave–structure interactions remain a significant challenge in ship and ocean engineering. Ensuring the safety and reliability of floating structures requires precise monitoring of dynamic water interactions, particularly in extreme sea conditions. Recent developments in computer vision and artificial intelligence have enabled advanced image-based sensing techniques that complement traditional measurement methods. This study investigates the application of Computerized Video Analysis (CVA) for water surface tracking in maritime experimental tests, marking the first exploration of digitalized experimental video analysis at the Australian Maritime College (AMC). The objective is to integrate CVA into laboratory data acquisition systems, enhancing the accuracy and robustness of wave interaction measurements. A novel algorithm was developed to track water surfaces near floating structures, with its effectiveness assessed through a Wave Energy Converter (WEC) experiment. The method successfully captured wave runup interactions with the hull form, operating alongside traditional sensors to evaluate spectral responses at a wave height of 0.4 m. Moreover, its application in irregular wave conditions demonstrated the algorithm’s capability to reliably detect the waterline across varying wave heights and periods. The findings highlight CVA as a reliable and scalable approach for improving safety assessments in maritime structures. Beyond controlled laboratory environments, this method holds potential for real-world applications in offshore wind turbines, floating platforms, and ship stability monitoring, contributing to enhanced structural reliability under operational and extreme sea states. Full article

(This article belongs to the Special Issue Safety and Reliability of Ship and Ocean Engineering Structures)

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31 pages, 1843 KiB

Open AccessArticle

Deep Q-Learning Based Adaptive MAC Protocol with Collision Avoidance and Efficient Power Control for UWSNs

by Wazir Ur Rahman, Qiao Gang, Feng Zhou, Muhammad Tahir, Wasiq Ali, Muhammad Adil and Muhammad Ilyas Khattak

J. Mar. Sci. Eng. 2025, 13(3), 616; https://doi.org/10.3390/jmse13030616 - 20 Mar 2025

Viewed by 316

Abstract

Underwater wireless sensor networks (UWSNs) widely used for maritime object detection or for monitoring of oceanic parameters that plays vital role prediction of tsunami to life-cycle of marine species by deploying sensor nodes at random locations. However, the dynamic and unpredictable underwater environment [...] Read more.

Underwater wireless sensor networks (UWSNs) widely used for maritime object detection or for monitoring of oceanic parameters that plays vital role prediction of tsunami to life-cycle of marine species by deploying sensor nodes at random locations. However, the dynamic and unpredictable underwater environment poses significant challenges in communication, including interference, collisions, and energy inefficiency. In changing underwater environment to make routing possible among nodes or/and base station (BS) an adaptive receiver-initiated deep adaptive with power control and collision avoidance MAC (DAWPC-MAC) protocol is proposed to address the challenges of interference, collisions, and energy inefficiency. The proposed framework is based on Deep Q-Learning (DQN) to optimize network performance by enhancing collision avoidance in a varying sensor locations, conserving energy in changing path loss with respect to time and depth and reducing number of relaying nodes to make communication reliable and ensuring synchronization. The dynamic and unpredictable underwater environment, shaped by variations in environmental parameters such as temperature (T) with respect to latitude, longitude, and depth, is carefully considered in the design of the proposed MAC protocol. Sensor nodes are enabled to adaptively schedule wake-up times and efficiently control transmission power to communicate with other sensor nodes and/or courier node plays vital role in routing for data collection and forwarding. DAWPC-MAC ensures energy-efficient and reliable time-sensitive data transmission, improving the packet delivery rati (PDR) by 14%, throughput by over 70%, and utility by more than 60% compared to existing methods like TDTSPC-MAC, DC-MAC, and ALOHA MAC. These enhancements significantly contribute to network longevity and operational efficiency in time-critical underwater applications. Full article

(This article belongs to the Special Issue Maritime Communication Networks and 6G Technologies)

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15 pages, 3983 KiB

Open AccessArticle

Estuarine Floc Mass Distributions from Aggregation/Disaggregation and Bed Sediment Exchange

by William H. McAnally, Ashish J. Mehta, Andrew J. Manning and Carola Forlini

J. Mar. Sci. Eng. 2025, 13(3), 615; https://doi.org/10.3390/jmse13030615 - 20 Mar 2025

Viewed by 211

Abstract

Estuarine benthos, among other lifeforms of interest to water quality, can be sensitive to size-distributed suspended cohesive flocs. In such a context, tide-dependent floc mass distributions in the Tamar Estuary in the UK are revisited. At the field site close to maximum turbidity, [...] Read more.

Estuarine benthos, among other lifeforms of interest to water quality, can be sensitive to size-distributed suspended cohesive flocs. In such a context, tide-dependent floc mass distributions in the Tamar Estuary in the UK are revisited. At the field site close to maximum turbidity, time-series of the water level, current velocity, salinity, and suspended sediment concentration (SSC) were recorded in 1998 over several tidal cycles. Concurrently, at selected times and elevation, floc mass distributions were derived from in situ observations of the SSC, floc diameters, and settling velocities. A previously developed time-dependent model, revised to account for both multiclass floc aggregation/disaggregation and bed sediment exchange by erosion and deposition, is applied to simulate mass distributions during ebb/flood cycles on 24 June and 5 August. Although the model does not account for the density effects of salinity or sediment advection, limited comparisons between simulated and observed mass distributions indicate generally good agreement in median diameter prediction on both days. This concurrence is due to the primary role of suspended floc dynamics and only a secondary contribution from bed sediment exchange in governing floc properties. For a better prediction of the SSC variation with the tide, the effects of salinity and advection can be incorporated by coupling the modeled floc dynamics with a suitable multi-dimensional hydrodynamic code. Full article

(This article belongs to the Special Issue Hydrodynamics and Water Quality in Coastal Systems: Numerical Modelling and Observations)

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19 pages, 3358 KiB

Open AccessReview

Towards a Digital Information Platform for Locating and Assessing Environmental Impacts of Submarine Groundwater Discharge: Examples from the Baltic Sea

by Klaus Hinsby, Jan Scholten, Joonas Virtasalo, Beata Szymczycha, Jørgen O. Leth, Lærke T. Andersen, Maria Ondracek, Jørgen Tulstrup, Michał Latacz and Rudolf Bannasch

J. Mar. Sci. Eng. 2025, 13(3), 614; https://doi.org/10.3390/jmse13030614 - 20 Mar 2025

Viewed by 554

Abstract

The number of studies on submarine groundwater discharge (SGD) and the evidence of its significance in biogeochemical cycling and potential impacts on the chemical and ecological status of coastal waters is increasing globally. Here, we briefly present SGD studies from the Baltic Sea [...] Read more.

The number of studies on submarine groundwater discharge (SGD) and the evidence of its significance in biogeochemical cycling and potential impacts on the chemical and ecological status of coastal waters is increasing globally. Here, we briefly present SGD studies from the Baltic Sea identified along the coastlines of Denmark, Finland, Germany, Poland, Sweden and Russia in the southwestern, southern and north–northeastern parts of the Baltic Sea. We introduce a digital SGD map viewer and information platform enabling easy overview and access to information on identified SGD sites in the coastal areas of the Baltic Sea. SGDs potentially transport critical pollutants from urban and agricultural areas on land to the marine environment. The pollutants include nutrients, dissolved organic and inorganic carbon, metals, pharmaceuticals, and other emerging contaminants, potentially harming marine ecosystems and biodiversity and possibly contributing to the poor chemical or ecological status of coastal waters, affecting human and environmental health. We focus on case studies from Finland, Germany, Poland and Denmark that include the results and interpretations from the applied geochemical, geophysical and geological methods, as well as bionic autonomous underwater vehicles (AUVs) for locating, investigating, modelling and visualizing SGD sites in 2D and 3D. The potential Pan-European or even global SGD information platform established within the European Geological Data Infrastructure (EGDI) enables the easy combination and comparison of map layers such as seabed sediment types and coastal habitats. The EGDI map viewer provides easy access to information from SGD studies and may serve as an entry point to relevant information on SGDs, including contents of pollutants, for the scientific community and policy-makers. The information potentially includes the results of model simulations, data from near real-time sensors at permanently installed monitoring stations and surveys in time and space conducted by AUVs. The presented digital SGD information platform is particularly pertinent to the UN Sustainable Development Goal (SDG) No. 14, which focuses on the conservation and sustainable use of oceans and marine resources. Full article

(This article belongs to the Special Issue Marine Environmental Analysis and Monitoring: Recent Harmful Events and New Substances)

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Graphical abstract

19 pages, 5299 KiB

Open AccessArticle

Precise PIV Measurement in Low SNR Environments Using a Multi-Task Convolutional Neural Network

by Yichao Wang, Chenxi You, Di Peng, Pengyu Lv and Hongyuan Li

J. Mar. Sci. Eng. 2025, 13(3), 613; https://doi.org/10.3390/jmse13030613 - 19 Mar 2025

Viewed by 246

Abstract

Particle Image Velocimetry (PIV) is essential in experimental fluid mechanics, providing nonintrusive flow field measurements. Among the recent advances in PIV algorithms, deep-learning-based optical flow estimation is distinguished by its high spatial and temporal resolution, as well as remarkable efficiency, especially RAFT-PIV, which [...] Read more.

Particle Image Velocimetry (PIV) is essential in experimental fluid mechanics, providing nonintrusive flow field measurements. Among the recent advances in PIV algorithms, deep-learning-based optical flow estimation is distinguished by its high spatial and temporal resolution, as well as remarkable efficiency, especially RAFT-PIV, which is based on Recurrent All-Pairs Field Transforms (RAFT). However, RAFT-PIV is extremely susceptible to experimental conditions characterized by low signal-to-noise ratios (SNR), leading to unacceptable errors. This study proposes PIV-RAFT-EN, an enhanced RAFT-based algorithm integrating image denoising, enhancement, and optical flow estimation via a Multi-Task Convolutional Neural Network (MTCNN). Evaluations on synthetic and real-world low-SNR data demonstrate its superior accuracy and efficiency. PIV-RAFT-EN offers a reliable solution for precise PIV measurements in challenging environments, including practical applications like vehicle water entry. Full article

(This article belongs to the Section Ocean Engineering)

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22 pages, 9426 KiB

Open AccessArticle

Experimental and Numerical Simulation Studies on the Flow Field Effects of Three Artificial Fish Reefs

by Peng Guo, Shuo Zhang, Shishi Zhu and Zhaoyang Jiang

J. Mar. Sci. Eng. 2025, 13(3), 612; https://doi.org/10.3390/jmse13030612 - 19 Mar 2025

Viewed by 213

Abstract

This paper focuses on three artificial reefs with different functionalities that are to be placed in the marine pasture in South Sulawesi Province, Indonesia, investigating the effects of different incoming current velocities and headward current angles on their flow field effects and aiming [...] Read more.

This paper focuses on three artificial reefs with different functionalities that are to be placed in the marine pasture in South Sulawesi Province, Indonesia, investigating the effects of different incoming current velocities and headward current angles on their flow field effects and aiming to explore the flow field effects of the three reefs and analyze the functionality of their flow fields and flow regimes on the sea area. A combination of PIV experiments and numerical simulation is used to analyze the velocity at the measurement point of the flume, the characteristics of the cross-section flow pattern, and the flow field effects under different incoming velocities and head-on angles, and the accuracy of numerical simulation is verified by flume tests. The results show that the changes in the incoming velocity and the angle of flow on the three reefs have different effects on the volume of upwelling and back eddy; the shape of the reef and the internal structure of the reef do not have any impact on the flow pattern, and the changes in the flow field are different under different conditions. The scale of the flow field reaches optimization under specific conditions. Full article

(This article belongs to the Section Coastal Engineering)

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18 pages, 3633 KiB

Open AccessArticle

Flying Robots Teach Floating Robots—A Machine Learning Approach for Marine Habitat Mapping Based on Combined Datasets

by Zacharias Kapelonis, Georgios Chatzigeorgiou, Manolis Ntoumas, Panos Grigoriou, Manos Pettas, Spyros Michelinakis, Ricardo Correia, Catarina Rasquilha Lemos, Luis Menezes Pinheiro, Caio Lomba, João Fortuna, Rui Loureiro, André Santos and Eva Chatzinikolaou

J. Mar. Sci. Eng. 2025, 13(3), 611; https://doi.org/10.3390/jmse13030611 - 19 Mar 2025

Viewed by 388

Abstract

Unmanned aerial and autonomous surface vehicles (UAVs and ASVs, respectively) are two emerging technologies for the mapping of coastal and marine environments. Using UAV photogrammetry, the sea-bottom composition can be resolved with very high fidelity in shallow waters. At greater depths, acoustic methodologies [...] Read more.

Unmanned aerial and autonomous surface vehicles (UAVs and ASVs, respectively) are two emerging technologies for the mapping of coastal and marine environments. Using UAV photogrammetry, the sea-bottom composition can be resolved with very high fidelity in shallow waters. At greater depths, acoustic methodologies have far better propagation properties compared to optics; therefore, ASVs equipped with multibeam echosounders (MBES) are better-suited for mapping applications in deeper waters. In this work, a sea-bottom classification methodology is presented for mapping the protected habitat of Mediterranean seagrass Posidonia oceanica (habitat code 1120) in a coastal subregion of Heraklion (Crete, Greece). The methodology implements a machine learning scheme, where knowledge obtained from UAV imagery is embedded (through training) into a classifier that utilizes acoustic backscatter intensity and features derived from the MBES data provided by an ASV. Accuracy and precision scores of greater than 85% compared with visual census ground-truth data for both optical and acoustic classifiers indicate that this hybrid mapping approach is promising to mitigate the depth-induced bias in UAV-only models. The latter is especially interesting in cases where the studied habitat boundaries extend beyond depths that can be studied via aerial devices’ optics, as is the case with P. oceanica meadows. Full article

(This article belongs to the Special Issue Research Progress on Ocean Observations Technology and Information Systems)

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19 pages, 6738 KiB

Open AccessArticle

Extreme Short-Term Prediction of Unmanned Surface Vessel Nonlinear Motion Under Waves

by Yiwen Wang, Jian Li, Shan Wang, Hantao Zhang, Long Yang and Weiguo Wu

J. Mar. Sci. Eng. 2025, 13(3), 610; https://doi.org/10.3390/jmse13030610 - 19 Mar 2025

Viewed by 179

Abstract

Under complex hydrodynamic conditions, Unmanned Surface Vessel (USV) exhibits non-stationary and nonlinear dynamic behaviors. Extreme short-term prediction of such nonlinear motion is therefore critical for ensuring navigational safety. To improve the prediction accuracy, a VMD-CNN-LSTM combined prediction model was applied based on Variational [...] Read more.

Under complex hydrodynamic conditions, Unmanned Surface Vessel (USV) exhibits non-stationary and nonlinear dynamic behaviors. Extreme short-term prediction of such nonlinear motion is therefore critical for ensuring navigational safety. To improve the prediction accuracy, a VMD-CNN-LSTM combined prediction model was applied based on Variational Mode Decomposition (VMD), Convolutional Neural Network (CNN), and Long Short-term Memory (LSTM) neural network. The methodology employs VMD to decompose the nonlinear motion time series data of the USV obtained by numerical simulation into stationary Intrinsic Mode Functions (IMFs), subsequently extracting spatial features from these IMFs using CNN layers, and, finally, predicts temporal sequence via the LSTM module. Comparative analyses highlight the better performance of the VMD-CNN-LSTM model over standalone LSTM and CNN-LSTM models in predicting nonlinear motion under varying significant wave heights. At a Prediction Advance Time (PAT) of 3.7 s, the VMD-CNN-LSTM model improves prediction accuracy by 13.3% for a wave height of 1.015 m (Case I) and 54.9% for a wave height of 1.998 m (Case II) compared to the CNN-LSTM model. With a PAT of 5.6 s, the accuracy gains increase to 32.9% for Case I and 94.6% for Case II, demonstrating the model’s robustness in extended prediction scenarios. Full article

(This article belongs to the Section Ocean Engineering)

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34 pages, 13993 KiB

Open AccessArticle

Multi-Scale Pore Structure of Terrestrial, Transitional, and Marine Shales from China: Insights into Porosity Evolution with Increasing Thermal Maturity

by Zhongrui Wu, Ralf Littke, Shuo Qin, Yahao Huang, Sheng He, Gangyi Zhai, Zhengqing Huang and Kaiming Wang

J. Mar. Sci. Eng. 2025, 13(3), 609; https://doi.org/10.3390/jmse13030609 - 19 Mar 2025

Viewed by 273

Abstract

Organic matter (OM)-hosted pores play a crucial role in unconventional shale reservoirs, with their development influenced by OM type and thermal maturity across terrestrial, transitional, and marine deposits. In this study, a comparative analysis of porosity and pore structures is presented using organic [...] Read more.

Organic matter (OM)-hosted pores play a crucial role in unconventional shale reservoirs, with their development influenced by OM type and thermal maturity across terrestrial, transitional, and marine deposits. In this study, a comparative analysis of porosity and pore structures is presented using organic petrographical, petrophysical, and mineralogical methods on organic-rich samples from diverse depositional environments. A pore evolution model for these sediments in different settings is proposed. Results show that kerogen particles in terrestrial shales at low and moderate thermal maturity (Dameigou Formation and Qingshankou Formation) are mostly nonporous. Transitional shales (Longtan Formation) contain vitrinite and inertinite, with only some inertinite exhibiting visible primary pores. In marine shales at higher maturity (late oil window; Dalong Formation), the interparticle pore space is occupied by solid bitumen, and secondary porosity is present at higher maturity, approaching the thermal gas generation stage. In over-mature marine shales (Wujiaping and Daye Formations), secondary pores are densely distributed within pyrobitumen. A negative correlation between organic carbon content and pore volume is observed in low-maturity lacustrine and transitional shales due to poorly developed kerogen-bound pores and interparticle pore occlusion by solid bitumen. However, over-mature marine shales exhibit a strong positive correlation due to extensive secondary porosity in pyrobitumen. Thus, pore evolution within OM is controlled by kerogen type and maturity. In oil-prone marine and lacustrine shales, secondary porosity in solid bitumen and pyrobitumen increases with thermal maturity. In contrast, terrestrial kerogen rarely forms solid bitumen and mainly develops micropores rather than mesopores at high maturity. Full article

(This article belongs to the Section Marine Energy)

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25 pages, 20356 KiB

Open AccessArticle

Optimization Strategy for Container Transshipment Between Yards at U-Shaped Sea-Rail Intermodal Terminal

by Zeyi Liu and Junjun Li

J. Mar. Sci. Eng. 2025, 13(3), 608; https://doi.org/10.3390/jmse13030608 - 19 Mar 2025

Viewed by 200

Abstract

The U-shaped automated container terminal (U-ACT) meets the requirements of sea-rail intermodal transportation with its unique layout. However, this layout also presents challenges, such as complex container transshipment planning and challenging equipment scheduling, which limit further improvements in overall efficiency. This paper focuses [...] Read more.

The U-shaped automated container terminal (U-ACT) meets the requirements of sea-rail intermodal transportation with its unique layout. However, this layout also presents challenges, such as complex container transshipment planning and challenging equipment scheduling, which limit further improvements in overall efficiency. This paper focuses on the integrated scheduling of horizontal transportation and container-handling equipment for container transshipment at U-ACT. To minimize operation time and energy consumption while addressing path conflicts among container trucks, we designed a two-layer scheduling model to generate an optimal scheduling scheme for each automated device. Given the complexity of the problem, we developed a reinforcement learning-driven hyper-heuristic algorithm (RLHA) capable of efficiently searching for near-optimal solutions. Small-scale experiments demonstrate that our RLHA outperforms other algorithms, improving optimization results by 5.14% to 28.87% when the number of container operation tasks reaches 100. Finally, large-scale experiments were conducted to analyze key factors impacting sea-rail intermodal transport operations at U-ACT, providing a foundation for practical optimization. Full article

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21 pages, 31533 KiB

Open AccessArticle

Effects of Different Cryoprotectants on Cryopreservation of Sperm from Noble Scallop Mimachlamys nobilis

by Minghao Li, Zhengyi Fu, Gang Yu and Zhenhua Ma

J. Mar. Sci. Eng. 2025, 13(3), 607; https://doi.org/10.3390/jmse13030607 - 19 Mar 2025

Viewed by 411

Abstract

In cryopreservation technology, the choice of cryoprotectant plays a crucial role in cell survival and function. Different types of cryoprotectants, each with unique protective mechanisms, mitigate cellular damage from ice crystal formation during freezing. This study investigated the effects of different types and [...] Read more.

In cryopreservation technology, the choice of cryoprotectant plays a crucial role in cell survival and function. Different types of cryoprotectants, each with unique protective mechanisms, mitigate cellular damage from ice crystal formation during freezing. This study investigated the effects of different types and concentrations of cryoprotectants on the cryopreservation efficacy of noble scallop Mimachlamys nobilis sperm. Six cryoprotectants were tested, including four permeable cryoprotectants (dimethyl sulfoxide (DMSO), ethylene glycerol (EG), propylene glycerol (PG), methanol (MET)) and two non-permeable cryoprotectants (trehalose (TRE), fetal bovine serum (FBS)). The results showed that permeable cryoprotectants, which penetrate the cell membrane, regulate the osmotic pressure inside and outside cells to reduce dehydration damage. Among them, 10% DMSO provided the best protection, significantly preserving sperm motility, velocity, and morphology. Non-permeable cryoprotectants, although unable to penetrate cells, stabilized the extracellular environment at higher concentrations (such as FBS). Additionally, MET and FBS exhibited enhanced protective effects with increasing concentration, indicating their potential in reducing sperm structural damage at higher concentrations. Morphological observations indicated that freezing caused varying degrees of structural damage to sperm, with flagellar integrity being crucial for motility. Overall, selecting an appropriate cryoprotectant and concentration is essential for the efficient cryopreservation of M. nobilis sperm, providing a valuable reference for conserving germplasm resources of marine species. 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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12 pages, 2964 KiB

Open AccessArticle

Azimuthal Variation in the Surface Wave Velocity of the Philippine Sea Plate

by Víctor Corchete

J. Mar. Sci. Eng. 2025, 13(3), 606; https://doi.org/10.3390/jmse13030606 - 19 Mar 2025

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Abstract

A study of the azimuthal variation in the surface wave fundamental-mode phase velocity is performed for the Philippine Sea Plate (PSP). This azimuthal variation has been anisotropically inverted for the PSP to determine the isotropic and anisotropic structure of this plate from 0 [...] Read more.

A study of the azimuthal variation in the surface wave fundamental-mode phase velocity is performed for the Philippine Sea Plate (PSP). This azimuthal variation has been anisotropically inverted for the PSP to determine the isotropic and anisotropic structure of this plate from 0 to 260 km. This azimuthal variation is due to anisotropy in the upper mantle. The crust is found in an isotropic structure, but the lithosphere and asthenosphere exhibit anisotropic structures. For the lithosphere, the main cause of anisotropy is the alignment of anisotropic crystals approximately parallel to the direction of seafloor spreading, and the fast axis of the seismic velocity is in the direction of ~163° of azimuth. For the asthenosphere, the seismic anisotropy can be derived from the lattice-preferred orientation (LPO) in response to the shear strains induced by mantle flow, and the fast axis of the seismic velocity is also the direction of ~163° of azimuth. This result suggests that a mantle flow pattern may occur in the asthenosphere and seems to be approximately parallel to the direction of seafloor spreading observed for the lithosphere. Finally, the changes in the parameter ξ with depth are studied to estimate the depth of the lithosphere–asthenosphere boundary (LAB), observing a clear change in this parameter at 80 km depth. Full article

(This article belongs to the Special Issue Storm Tide and Wave Simulations and Assessment, 3rd Edition)

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11 pages, 1458 KiB

Open AccessArticle

Evaluation of Measurement Uncertainty for the Wave Buoy Calibration Device Using a Vertical Lifting Method

by Yafei Huang, Donglei Zhao, Chenhao Gao, Tian Yan and Lijun He

J. Mar. Sci. Eng. 2025, 13(3), 605; https://doi.org/10.3390/jmse13030605 - 19 Mar 2025

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Abstract

This study evaluates the measurement uncertainty of the wave buoy calibration device using a vertical lifting method to ensure the accuracy and reliability of wave buoy measurements for marine research. The calibration device employs a linear motor-driven vertical displacement system, integrating a standard [...] Read more.

This study evaluates the measurement uncertainty of the wave buoy calibration device using a vertical lifting method to ensure the accuracy and reliability of wave buoy measurements for marine research. The calibration device employs a linear motor-driven vertical displacement system, integrating a standard steel tape for wave height measurement and a photoelectric switch-based time calibration module for wave period verification. To address the limitations of traditional instruments, the device utilizes a 0.1 mm laser beam and image processing software to enhance the resolution of the standard steel tape, reducing the smallest division measurement from 1 mm to 0.1 mm. Additionally, a high-precision time calibration method synchronizes the time of the motor’s upper computer software and a frequency meter, minimizing indication error. Key uncertainty sources, including repeatability, environmental temperature effects, and the smallest division measure of instrument, were systematically analyzed. Results demonstrate that the extended measurement uncertainty (k = 2) for wave heights of 0.03 m and 40 m are 0.058 mm and 1.088 mm, respectively, while the uncertainty for a 30 s wave period is 3 ms. These values meet the stringent accuracy requirements (0.5% of measured values) for calibrating advanced wave buoys like the Directional Waverider 4. The proposed device provides a robust solution for validating wave buoy performance, offering significant practical value for oceanographic studies and coastal engineering applications. Full article

(This article belongs to the Section Ocean Engineering)

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24 pages, 3435 KiB

Open AccessReview

A Systematic Review of Green Port Evaluation: Methods, Subjects, and Indicators

by Huaping Fei, Hongda Shi and Xinying Pan

J. Mar. Sci. Eng. 2025, 13(3), 604; https://doi.org/10.3390/jmse13030604 - 19 Mar 2025

Viewed by 557

Abstract

In the context of global carbon neutrality goals and the transition to clean energy, ports have become a focal point due to their significant energy consumption and pollution emissions. This heightened attention has promoted research on green ports, with comprehensive evaluations of their [...] Read more.

In the context of global carbon neutrality goals and the transition to clean energy, ports have become a focal point due to their significant energy consumption and pollution emissions. This heightened attention has promoted research on green ports, with comprehensive evaluations of their environmental impact serving as a key driver of sustainable transformation. This paper presents a systematic review of 15 years of literature, uncovering key research directions and emerging trends in green port evaluation. It explores the evolution of evaluation methods and indicator systems tailored to diverse evaluation subjects. The findings highlight three key trends: segmentation of evaluation subjects, refinement of evaluation methods, and dynamic adaptation of indicators. By providing a comprehensive overview of the current evaluation practices, this study offers valuable theoretical insights and actionable guidance to support future research and facilitate the practical implementation of green ports initiatives. Full article

(This article belongs to the Section Ocean Engineering)

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1 pages, 303 KiB

Open AccessCorrection

Correction: Chen et al. Design of a Sliding Mode Controller for Lateral Motion Control of a Supercavitating Vehicle Based on a Radial Basis Function Neural Network Observer. J. Mar. Sci. Eng. 2025, 13, 418

by Shangze Chen, Xinhua Zhao and Xiufen Ye

J. Mar. Sci. Eng. 2025, 13(3), 603; https://doi.org/10.3390/jmse13030603 - 19 Mar 2025

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Abstract

There was an error in the original paper [...] Full article

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18 pages, 3316 KiB

Open AccessArticle

Gut Microbiota Response to Experimental Acute Cold Stress in Juvenile Yellowfin Tuna (Thunnus albacares)

by Junhua Huang, Zhengyi Fu, Wei Yu, Bowen Hou, Jinhui Wu, Tao Zhang and Zhenhua Ma

J. Mar. Sci. Eng. 2025, 13(3), 602; https://doi.org/10.3390/jmse13030602 - 18 Mar 2025

Viewed by 198

Abstract

Environmental temperature declines significantly impact the physiological processes of marine organisms, particularly under the cool La Nina conditions, challenging yellowfin tuna (Thunnus albacares) aquaculture. Low temperatures affect fish metabolism and immune functions and can alter the gut microbiota composition, influencing health [...] Read more.

Environmental temperature declines significantly impact the physiological processes of marine organisms, particularly under the cool La Nina conditions, challenging yellowfin tuna (Thunnus albacares) aquaculture. Low temperatures affect fish metabolism and immune functions and can alter the gut microbiota composition, influencing health and growth. This study investigates the impact of low temperatures on the gut microbiota of juvenile yellowfin tuna. Fish were divided into a Low Temperature (LT) group (24 °C), an Ultra Low Temperature (ULT) group (18 °C), and a Control group (CG) (30 °C), with evaluations at 0, 12, 24, and 36 h using α-diversity analysis and microbial species composition. Results indicated a significant increase in the Ace index for the ULT group after 36 h of cold stress (p < 0.05), with no significant changes in the Shannon index. A decline in Proteobacteria and increases in Verrucomicrobiota and Firmicutes were observed in both LT and ULT groups. Additionally, both LT and ULT groups showed a significant rise in the Ace index at 36 h (p < 0.05), with a significant decrease in the Shannon index in the ULT group at 24 h. Furthermore, Firmicutes significantly increased at 12 h in both temperature groups (p < 0.05). These findings highlight the potential role of the gut microbiome in adapting yellowfin tuna to cold environments and provide microbial insights into their physiological adaptations, laying a foundation for further research and practical applications in aquaculture under cold conditions. 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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22 pages, 11028 KiB

Open AccessArticle

Research on the Control Method for Remotely Operated Vehicle Active Docking with Autonomous Underwater Vehicles Based on GFSMO-NMPC

by Hongxu Dai, Yunxiu Zhang, Shengguo Cui, Xinhui Zheng and Qifeng Zhang

J. Mar. Sci. Eng. 2025, 13(3), 601; https://doi.org/10.3390/jmse13030601 - 18 Mar 2025

Viewed by 284

Abstract

This study proposes a control method for Remotely Operated Vehicles (ROVs) to actively dock with AUVs, to address the limitations of traditional docking and recovery schemes for Autonomous Underwater Vehicles (AUVs), such as restricted maneuverability and external disturbances. Firstly, a process and control [...] Read more.

This study proposes a control method for Remotely Operated Vehicles (ROVs) to actively dock with AUVs, to address the limitations of traditional docking and recovery schemes for Autonomous Underwater Vehicles (AUVs), such as restricted maneuverability and external disturbances. Firstly, a process and control strategy for ROV active docking with AUVs is designed, improving docking safety. Secondly, a Nonlinear Model Predictive Controller (NMPC) based on a Gaussian Function Sliding Mode Observer (GFSMO) compensation is designed for the ROV, generating smooth control inputs to achieve high-precision trajectory tracking and real-time docking. Finally, a joint simulation experiment is established through WEBOTS 2023a and MATLAB 2023a, verifying the superiority and feasibility of the designed controller and the proposed method. After parameter optimization, the simulation results show the method proposed in this study has a 90% success rate in 10 docking experiments under different disturbances. Full article

(This article belongs to the Section Ocean Engineering)

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19 pages, 4946 KiB

Open AccessArticle

Fast and Stable Scanning Technology for a Rotating Dual Grating Based on Inertial Navigation Feedforward and Fuzzy PID Control for Shipborne Platforms

by Wang Xi, Yang Liu, Yunjie Teng, Qiran Wang, Hengjie Wang, Fujing Zhang, Fengshou Shi and Xinqing Yi

J. Mar. Sci. Eng. 2025, 13(3), 600; https://doi.org/10.3390/jmse13030600 - 18 Mar 2025

Viewed by 200

Abstract

To achieve fast and stable scanning on lightweight shipborne electro-optical platforms, we propose a rotating dual-grating two-dimensional scanning system with inertial navigation feedforward and Fuzzy PID control. First, a two-dimensional scanning model using rotating dual grating with inertial navigation feedforward technology was proposed; [...] Read more.

To achieve fast and stable scanning on lightweight shipborne electro-optical platforms, we propose a rotating dual-grating two-dimensional scanning system with inertial navigation feedforward and Fuzzy PID control. First, a two-dimensional scanning model using rotating dual grating with inertial navigation feedforward technology was proposed; in that system, the required positional information for the two gratings is determined based on the target location data. Then, the scanning model was combined with the Fuzzy PID algorithm to design a servo system controller that controls the dual gratings to perform beam deflection and scanning, then simulation. Finally, an experimental platform was built for validation. Under a sea-surface disturbance of 10° at 0.1 Hz, the scanning error of the entire process was controlled within 0.328 mrad (RMS) and the scanning of a 15° (half-angle) circular region was completed within 28 s. Compared with traditional control systems, significant improvements were achieved, with the scanning accuracy increased by more than 40.85% and the scanning speed improved by over 21.42%. This paper provides a reference for the application of a rotating dual grating electro-optical scanning platform on shipborne platforms. Full article

(This article belongs to the Special Issue Intelligent Approaches to Marine Engineering Research)

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15 pages, 4634 KiB

Open AccessArticle

Efficient One-Dimensional Network Design Method for Underwater Acoustic Target Recognition

by Qing Huang, Xiaoyan Zhang, Anqi Jin, Menghui Lei, Mingmin Zeng, Peilin Cao, Zihan Na and Xiangyang Zeng

J. Mar. Sci. Eng. 2025, 13(3), 599; https://doi.org/10.3390/jmse13030599 - 18 Mar 2025

Viewed by 207

Abstract

Many studies have used various time-frequency feature extraction methods to convert ship-radiated noise into three-dimensional (3D) data suitable for computer vision (CV) models, which have shown good results in public datasets. However, traditional feature engineering (FE) has been enhanced to interface matching–feature engineering [...] Read more.

Many studies have used various time-frequency feature extraction methods to convert ship-radiated noise into three-dimensional (3D) data suitable for computer vision (CV) models, which have shown good results in public datasets. However, traditional feature engineering (FE) has been enhanced to interface matching–feature engineering (IM-FE). This approach requires considerable effort in feature design, larger sample duration, or a higher upper limit of frequency. In this context, this paper proposes a one-dimensional network design for underwater acoustic target recognition (UATR-ND1D), only combined with fast Fourier transform (FFT), which can effectively alleviate the problem of IM-FE. This method is abbreviated as FFT-UATR-ND1D. FFT-UATR-ND1D was applied to the design of a one-dimensional network, named ResNet1D. Experiments were conducted on two mainstream datasets, using ResNet1D in 4320 and 360 tests, respectively. The lightweight model ResNet1D_S, with only 0.17 M parameters and 3.4 M floating point operations (FLOPs), achieved average accuracies were 97.2% and 95.20%. The larger model, ResNet1D_B, with 2.1 M parameters and 5.0 M FLOPs, both reached optimal accuracies, 98.81% and 98.42%, respectively. Compared to existing methods, those with similar parameter sizes performed 3–5% worse than the methods proposed in this paper. Additionally, methods achieving similar recognition rates require more parameters of 1 to 2 orders of magnitude and FLOPs. Full article

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19 pages, 5537 KiB

Open AccessArticle

Predictive Study on the Cutting Energy Efficiency of Dredgers Based on Specific Cutting Energy

by Junlang Yuan, Ke Yang, Taiwei Yang, Haoran Xu, Ting Xiong and Shidong Fan

J. Mar. Sci. Eng. 2025, 13(3), 598; https://doi.org/10.3390/jmse13030598 - 18 Mar 2025

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Abstract

The suction-lifting system of cutter suction dredgers consumes a large amount of energy. Optimizing their performance is of great significance for enhancing the overall efficiency of dredgers. This study proposes the effective specific cutting energy, a new indicator suitable for evaluating the energy [...] Read more.

The suction-lifting system of cutter suction dredgers consumes a large amount of energy. Optimizing their performance is of great significance for enhancing the overall efficiency of dredgers. This study proposes the effective specific cutting energy, a new indicator suitable for evaluating the energy consumption of the cutting system of cutter suction dredgers. It reflects the cooperation state between the cutter system and the pump-pipe system and has important reference value for improving construction efficiency. The calculation method of the effective specific cutting energy is given, which is calculated by the cutter motor power, slurry concentration, and slurry flow rate. Based on the machine learning framework, a model framework for predicting the specific cutting energy according to the relevant parameters of the suction-lifting system is constructed. Real ship data from the cutter suction dredger “Changshi 12” are used for experiments. First, eigenvalue screening is carried out based on the dredging knowledge and mechanism, then outliers are removed, and finally data processing is performed using Spearman correlation coefficient and PCA dimensionality reduction techniques. Subsequently, five machine learning algorithms, such as RF and XGBoost, are used in combination with a grid search to find the optimal hyperparameters, and Lasso is used as the meta-learner to integrate the prediction results. The experimental results show that the Random Forest and Stacking models have high prediction accuracy for slurry concentration, cutter motor power, and slurry flow rate, verifying the feasibility of this method. Full article

(This article belongs to the Special Issue Intelligent Systems for Marine Transportation)

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27 pages, 10493 KiB

Open AccessArticle

Mechanical Evaluation of Casing in Multiple Thermal Recovery Cycles for Offshore Heavy Oil Wells

by Yuxian He, Yongpeng Song, Shenghua Hu, Hangming Liu and Xianchi Ge

J. Mar. Sci. Eng. 2025, 13(3), 597; https://doi.org/10.3390/jmse13030597 - 18 Mar 2025

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Abstract

China’s offshore heavy oil resources are abundant but underutilized. Circulating steam stimulation enhances production while increasing casing failure risks in thermal recovery wells. Accurately assessing casing performance after repeated thermal cycles is crucial for ensuring wellbore integrity. This paper presents tensile and creep [...] Read more.

China’s offshore heavy oil resources are abundant but underutilized. Circulating steam stimulation enhances production while increasing casing failure risks in thermal recovery wells. Accurately assessing casing performance after repeated thermal cycles is crucial for ensuring wellbore integrity. This paper presents tensile and creep experiments on TP110H casing under cyclic temperatures. The temperature distribution within the “casing-cement sheath-stratum” system is derived using heat transfer theory. Stress and displacement equations are established based on thick-walled cylinder theory and thermo-elasticity. Thermal coupling analysis assesses casing stress in straight, inclined, and sidetrack well sections. Key factors, including steam injection pressure, in situ stress, cement modulus, and prestress, are analyzed for their effects on cumulative strain below the packer. Strain-based methods evaluate casing safety. Results show that under thermal cycling at 350 °C, after 16 cycles, the casing’s elastic modulus, yield strength, and tensile strength decrease by 15.3%, 13.1%, and 10.1%, respectively, while the creep rate increases by 16.0%. Above the packer, the casing remains safe, but the lower section may be at risk. Using low-elasticity cement, higher steam injection pressure, and prestressing can help improve casing performance. This study provides guidance on enhancing casing safety and optimizing steam stimulation parameters. Full article

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25 pages, 2134 KiB

Open AccessArticle

Differential Evolution Deep Reinforcement Learning Algorithm for Dynamic Multiship Collision Avoidance with COLREGs Compliance

by Yangdi Shen, Zuowen Liao and Dan Chen

J. Mar. Sci. Eng. 2025, 13(3), 596; https://doi.org/10.3390/jmse13030596 - 17 Mar 2025

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Abstract

In ship navigation, determining a safe and economic path from start to destination under dynamic and complex environment is essential, but the traditional algorithms of current research are inefficient. Therefore, a novel differential evolution deep reinforcement learning algorithm (DEDRL) is proposed to address [...] Read more.

In ship navigation, determining a safe and economic path from start to destination under dynamic and complex environment is essential, but the traditional algorithms of current research are inefficient. Therefore, a novel differential evolution deep reinforcement learning algorithm (DEDRL) is proposed to address problems, which are composed of local path planning and global path planning. The Deep Q-Network is utilized to search the best path in target ship and multiple-obstacles scenarios. Furthermore, differential evolution and course-punishing reward mechanism are introduced to optimize and constrain the detected path length as short as possible. Quaternion ship domain and COLREGs are involved to construct a dynamic collision risk detection model. Compared with other traditional and reinforcement learning algorithms, the experimental results demonstrate that the DEDRL algorithm achieved the best global path length with 28.4539 n miles, and also performed the best results in all scenarios of local path planning. Overall, the DEDRL algorithm is a reliable and robust algorithm for ship navigation, and it also provides an efficient solution for ship collision avoidance. Full article

(This article belongs to the Section Ocean Engineering)

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20 pages, 11109 KiB

Open AccessArticle

Self-Propulsion Factors for Minimum Propulsion Power Assessment in Adverse Conditions

by Joon-Hyoung Lee, Seunghyun Hwang, Young-Yeon Lee, Woo-Seok Jin and Moon-Chan Kim

J. Mar. Sci. Eng. 2025, 13(3), 595; https://doi.org/10.3390/jmse13030595 - 17 Mar 2025

Viewed by 248

Abstract

Considering that slow steaming requires low engine power, which impedes maneuverability under severe sea conditions, the International Maritime Organization (IMO) provides guidelines for the minimum propulsion power (MPP) required to maintain ship maneuverability in adverse conditions. This study focused on the characteristics of [...] Read more.

Considering that slow steaming requires low engine power, which impedes maneuverability under severe sea conditions, the International Maritime Organization (IMO) provides guidelines for the minimum propulsion power (MPP) required to maintain ship maneuverability in adverse conditions. This study focused on the characteristics of self-propulsion factors in the context of MPP assessment to enhance MPP prediction accuracy. Overload tests were conducted at low speeds of advance, considering added resistance in adverse conditions. Moreover, propeller open-water tests were conducted corresponding to propeller flow with low Reynolds numbers to investigate their effect on self-propulsion factors. In addition, computational fluid dynamics (CFD) simulations were conducted to analyze physical phenomena such as the flow field and pressure distribution under model test conditions. The results indicated that the thrust deduction factor was lower than that given in the guidelines, whereas the wake fraction was higher at the required forward speed of 2 knots. The MPP assessment in this study revealed that the required brake power was 4–5% lower than that given in the guidelines, indicating that the guidelines need reviewing for a more reliable assessment. Full article

(This article belongs to the Section Ocean Engineering)

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17 pages, 11005 KiB

Open AccessArticle

Pervasive Millennial-Scale Interstadial/Interglacial Climate Variability in the High-Latitude Northern Hemisphere

by Steve P. Lund, Norbert Nowaczyk, Lloyd Keigwin and Jens Gruetzner

J. Mar. Sci. Eng. 2025, 13(3), 594; https://doi.org/10.3390/jmse13030594 - 17 Mar 2025

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Abstract

IODP Ex. 323 to the Bering Sea recovered a detailed record of Quaternary environmental variability adjacent to Alaska and eastern Siberia. The deep-sea sediment records show a dramatic bimodal environmental record of alternating high versus low magnetic susceptibility. Oxygen isotope records indicate that [...] Read more.

IODP Ex. 323 to the Bering Sea recovered a detailed record of Quaternary environmental variability adjacent to Alaska and eastern Siberia. The deep-sea sediment records show a dramatic bimodal environmental record of alternating high versus low magnetic susceptibility. Oxygen isotope records indicate that the interglacials are times of high clastic flux (high magnetic susceptibility) from the adjacent continents into the Bering Sea. Subsequent, more detailed chronostratigraphy indicates that Interstadial 3 and Interglacials 5, 7, and 9 are also intervals of large-amplitude, millennial-scale environmental variability alternating between warmer/wetter and cooler/drier intervals, with a quasi-cyclicity of ~5000 years. Comparative studies of North Atlantic Quaternary sediments associated with ODP Leg 172, with a similar dramatic glacial/interglacial variation in carbonate, show an almost identical millennial-scale (~5000 yrs) pattern of variability that we attribute to alternating warmer/cooler intervals in Interstadial 3 and Interglacials 5, 7, and 9. These results can also be compared to findings for Lake Elgygytgyn in Siberia. The chronology of this record is less certain than those of the other two regions, but it, too, shows large-amplitude changes in magnetic susceptibility in Interstadial 3 and Interglacials 5, 7, and 9 that can be attributed to oscillating warmer/cooler conditions on a millennial scale. These results suggest a coherent, hemispheric-scale pattern of climate variability in interstadial/interglacial periods of the last 400 ka with a quasi-cyclicity of ~5000 years. We speculate that this cyclicity is driven by a harmonic of the chaotic precession Milankovich cyclicity. Full article

(This article belongs to the Special Issue Recent Developments and Advances in Geological Oceanography and Ocean Observation in the Pacific Ocean and Its Marginal Basins)

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J. Mar. Sci. Eng., Volume 13, Issue 3 (March 2025) – 235 articles

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