Journal of Marine Science and Engineering

28 pages, 11471 KiB

Open AccessArticle

Unlocking Brazil’s Maritime Potential: Expanding Ports for Post-Panamax Operations

by Adriane Marques Pimenta, Martí Puig, Danielle Laura Bridi Mallman, Rodrigo Affonso de Albuquerque Nóbrega and R. M. Darbra

J. Mar. Sci. Eng. 2025, 13(5), 938; https://doi.org/10.3390/jmse13050938 (registering DOI) - 10 May 2025

Abstract

The Brazilian port sector faces an urgent need for modernization to meet the demands of the contemporary global economy. A significant challenge lies in the shallow depth of access channels, which hinders the navigation of larger ships with deeper drafts, and the fact [...] Read more.

The Brazilian port sector faces an urgent need for modernization to meet the demands of the contemporary global economy. A significant challenge lies in the shallow depth of access channels, which hinders the navigation of larger ships with deeper drafts, and the fact that many ports are constrained by the proximity of large cities, limiting their expansion. This study aims to identify Brazilian ports with the potential to accommodate post-Panamax ships, a critical component of modern maritime trade. Using a multi-criteria evaluation system, five key criteria were selected: water depth, land capacity for expansion, dredging requirements, water accessibility, and transport infrastructure. These criteria were systematically applied to 210 Brazilian port facilities, analyzed through QGIS 3.38.3 software using satellite imagery and literature sources. To prioritize the most suitable ports, Pareto analysis and quartile analysis were employed, resulting in the identification of 58 port facilities as prime candidates for expansion. This research provides a data-driven framework to guide the modernization of Brazilian ports, positioning them to better serve the growing demands of the global maritime industry. Full article

(This article belongs to the Special Issue Smart Seaport and Maritime Transport Management, Second Edition)

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13 pages, 2551 KiB

Open AccessArticle

Risk Assessment of International Seabed Mining Implementing the Analytic Hierarchy Process

by Xinyu Ma, Yejian Wang, Kehong Yang, Jinrong Li, Yan Li, Dongsheng Zhang, Rong Wang and Yinxia Fang

J. Mar. Sci. Eng. 2025, 13(5), 937; https://doi.org/10.3390/jmse13050937 (registering DOI) - 10 May 2025

Abstract

The international seabed area (“the Area”) harbors abundant metal mineral resources that are critical to address global metal supply–demand and sustainable development. However, exploitation of mineral resources in the Area faces complex risks spanning politics, economy, technology, science, environment, society, industry, and law. [...] Read more.

The international seabed area (“the Area”) harbors abundant metal mineral resources that are critical to address global metal supply–demand and sustainable development. However, exploitation of mineral resources in the Area faces complex risks spanning politics, economy, technology, science, environment, society, industry, and law. No commercial-scale deep-sea mining operations have been conducted to date. Systematic risk identification and prioritization can inform strategic planning for stakeholders. This study employs literature analysis and an 80-expert questionnaire to identify key risk factors affecting mineral exploitation in the Area. Using the Analytic Hierarchy Process (AHP), we quantitatively assess the relative importance and weightings of these risks. Our results indicate that Level 1 risk groups prioritize (1) policy and public opinion risk, (2) extended continental shelf (ECS) delineation risk, (3) high sea marine protected areas (HSMPAs) establishment risk, and (4) mining area economic value risk. The five most critical Level 2 risk factors are (i) policy changes in contractor states, (ii) ECS-mining area boundary conflicts, (iii) environmental provisions in exploitation regulations at the international seabed (ER), (iv) ER implementation delays, and (v) mineral resource uncertainty. These findings provide actionable insights for contractors, policymakers, and stakeholders to optimize decision making in deep-sea mining projects. Full article

(This article belongs to the Section Ocean Engineering)

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21 pages, 2321 KiB

Open AccessArticle

CKAN-YOLOv8: A Lightweight Multi-Task Network for Underwater Target Detection and Segmentation in Side-Scan Sonar

by Yao Xiao, Hualong Yang, Dongchen Dai, Hongjian Wang, Ziqi Shan and Hao Wu

J. Mar. Sci. Eng. 2025, 13(5), 936; https://doi.org/10.3390/jmse13050936 (registering DOI) - 10 May 2025

Abstract

Underwater target detection and segmentation in Side-Scan Sonar (SSS) imagery is challenged by low signal-to-noise ratios, geometric distortions, and Unmanned Underwater Vehicles (UUVs)’ computational constraints. This paper proposes CKAN-YOLOv8, a lightweight multi-task network integrating Kolmogorov–Arnold Networks Convolution (KANConv) into YOLOv8. The core innovation [...] Read more.

Underwater target detection and segmentation in Side-Scan Sonar (SSS) imagery is challenged by low signal-to-noise ratios, geometric distortions, and Unmanned Underwater Vehicles (UUVs)’ computational constraints. This paper proposes CKAN-YOLOv8, a lightweight multi-task network integrating Kolmogorov–Arnold Networks Convolution (KANConv) into YOLOv8. The core innovation replaces conventional convolutions with KANConv blocks using learnable B-spline activations, dynamically adapting to noise and multi-scale targets while ensuring parameter efficiency. The KANConv-based Path Aggregation Network (KANConv-PANet) mitigates geometric distortions through spline-optimized multi-scale fusion. A dual-task head combines CIoU loss-driven detection and a boundary-sensitive segmentation module with Dice loss. Evaluated on a dataset (50 raw images augmented to 2000), CKAN-YOLOv8 achieves state-of-the-art performance as follows: 0.869 AP@0.5 and 0.72 IoU, alongside real-time inference at 66 FPS. Ablation studies confirm the contributions of KANConv modules to noise robustness and multi-scale adaptability. The framework demonstrates exceptional robustness to noise, scalability across target sizes. Full article

(This article belongs to the Section Ocean Engineering)

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22 pages, 1990 KiB

Open AccessArticle

A Comparative Analysis of In Situ Testing Methods for Clay Strength Evaluation Using the Coupled Eulerian–Lagrangian Method

by Hebo Wang, Yifa Wang, Biao Li, Wengang Qi and Ning Wang

J. Mar. Sci. Eng. 2025, 13(5), 935; https://doi.org/10.3390/jmse13050935 - 9 May 2025

Abstract

The progression of marine resource exploration into deepwater and ultra-deepwater regions has intensified the requirement for precise quantification of the undrained shear strength of clay. Although diverse in situ testing methodologies—including the vane shear test (VST), cone penetration test (CPT), T-bar penetration test [...] Read more.

The progression of marine resource exploration into deepwater and ultra-deepwater regions has intensified the requirement for precise quantification of the undrained shear strength of clay. Although diverse in situ testing methodologies—including the vane shear test (VST), cone penetration test (CPT), T-bar penetration test (TPT), and ball penetration test (BPT)—are widely utilized for the assessment of clay strength, systematic discrepancies and correlations between their derived measurements remain inadequately resolved. The aim of this work is to provide a systematic comparison of strength interpretations across different in situ testing methods, with emphasis on identifying method-specific biases under varying soil behaviors. To achieve this, a unified numerical simulation framework was developed to simulate these four prevalent testing techniques, employing large-deformation finite element analysis via the Coupled Eulerian–Lagrangian (CEL) approach. The model integrates critical constitutive behaviors of marine clays, specifically strain softening and strain rate dependency, to replicate in situ shear strength evolution. Rigorous sensitivity analyses confirm the model’s robustness. The results indicate that, when the stain rate and softening effects are neglected, the resistance factors from the CPT and VST remain largely insensitive to shear strength variations. However, T-bar and ball penetrometers tend to underestimate strength by up to 15% in high-strength soils due to the incomplete development of a full-flow failure mechanism. As a result, their application in high-strength soils is not recommended. With both the strain rate and softening effects considered, the interpreted strength value S_ut from the CPT increases by 13.5% compared to cases excluding these effects, while other methods exhibit marginal decreases of 4–5%. The isolated analysis of strain softening reveals that, under identical softening parameters, the CPT demonstrates the least sensitivity to strain softening among the four methods examined, with the factor reduction ratio N_s/N₀ ranging from 0.76 to 1.00, while the other three methods range from 0.65 to 0.88. The results indicate that the CPT is well suited for strength testing in soils exhibiting pronounced softening behavior, as it reduces the influence of strain softening on the measured results. These findings provide critical insights into method-specific biases in undrained shear strength assessments, supporting a more reliable interpretation of in situ test data for deepwater geotechnical applications. Full article

(This article belongs to the Special Issue Wave–Structure–Seabed Interaction)

25 pages, 3631 KiB

Open AccessArticle

Hybrid Path Planning Method for USV Based on Improved A-Star and DWA

by Yan Liu, Zeqiang Sun, Junhe Wan, Hui Li, Delong Yang, Yanping Li, Wei Fu, Zhen Yu and Jichang Sun

J. Mar. Sci. Eng. 2025, 13(5), 934; https://doi.org/10.3390/jmse13050934 - 9 May 2025

Abstract

This paper presents a hybrid path planning method that integrates an enhanced A-Star algorithm with the Dynamic Window Approach (DWA). The proposed approach addresses the limitations of conventional A-Star algorithms in global path planning, particularly their inability to adaptively avoid obstacles in real-time. [...] Read more.

This paper presents a hybrid path planning method that integrates an enhanced A-Star algorithm with the Dynamic Window Approach (DWA). The proposed approach addresses the limitations of conventional A-Star algorithms in global path planning, particularly their inability to adaptively avoid obstacles in real-time. To improve navigation safety, the A-Star search strategy is enhanced by avoiding paths that intersect with obstacle vertices or pass through narrow channels. Additionally, a node optimization technique is introduced to remove redundant nodes by checking for collinearity in consecutive nodes. This optimization reduces the path length and ensures that the path maintains a safe distance from obstacles using parallel lines. An advanced Bézier curve smoothing method is also proposed, which adaptively selects control points to improve path smoothness and driving stability. By incorporating these improvements, the enhanced A-Star algorithm is combined with DWA to facilitate dynamic obstacle avoidance while generating global paths. The method accounts for the kinematic characteristics of the USV, as well as physical constraints such as linear and angular velocities, enabling effective handling of obstacles in dynamic environments and ensuring safe navigation. Simulation results demonstrate that the proposed algorithm generates secure global paths, significantly optimizing node count, path length, and smoothness, while effectively avoiding dynamic obstacles, thus ensuring safe navigation of the USV. Full article

(This article belongs to the Section Ocean Engineering)

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22 pages, 732 KiB

Open AccessArticle

Optimal State Estimation in Underwater Vehicle Discrete-Continuous Measurements via Augmented Hybrid Kalman Filter

by Vadim Kramar, Kirill Dementiev and Aleksey Kabanov

J. Mar. Sci. Eng. 2025, 13(5), 933; https://doi.org/10.3390/jmse13050933 - 9 May 2025

Abstract

The paper focuses on the optimal state-estimation algorithm for discrete-continuous systems. The research aim is to create an effective strategy for combining data from continuous and discrete information sources to improve the state estimation accuracy and reliability of complex dynamic systems. The paper [...] Read more.

The paper focuses on the optimal state-estimation algorithm for discrete-continuous systems. The research aim is to create an effective strategy for combining data from continuous and discrete information sources to improve the state estimation accuracy and reliability of complex dynamic systems. The paper discusses, in detail, the theoretical foundations of the proposed method, including the mathematical description of continuous and discrete models, and its optimality criterion formulation. State-vector augmentation is proposed to improve the estimation convergence. The authors present numerical modeling results demonstrating the algorithm’s efficiency on the example of motion parameter estimation for the autonomous underwater vehicle. The conclusions are drawn about the promising application for the developed algorithm in various fields related to information processing in complex technical systems, such as navigation, motion control, and state and processes monitoring. It is noted that the proposed approach can be generalized to the case of more sources’ fusion. The paper is considered to be valuable for specialists in control theory and signal and information processing, as well as for navigation and motion-control system designers. The results obtained may find practical application in the development of high-precision state-estimation systems in various technical applications. Full article

(This article belongs to the Special Issue Marine Technology: Latest Advancements and Prospects)

29 pages, 12468 KiB

Open AccessArticle

Navigation Attitude Prediction for Unmanned Surface Vessels in Wave Environments Using Improved Unscented Kalman Filter and Digital Twin Model

by Shaochun Qu, Xuemeng Men, Minghao Liu, Jian Cui, Husheng Wu and Yanfang Fu

J. Mar. Sci. Eng. 2025, 13(5), 932; https://doi.org/10.3390/jmse13050932 - 9 May 2025

Abstract

Unmanned surface vehicles (USVs) face significant challenges in long-term operations in complex and dynamic marine environments. These include abnormal attitudes, low accuracy in navigation attitude prediction, and difficulties in maintaining operational stability and equipment safety. To address these issues, this paper proposed a [...] Read more.

Unmanned surface vehicles (USVs) face significant challenges in long-term operations in complex and dynamic marine environments. These include abnormal attitudes, low accuracy in navigation attitude prediction, and difficulties in maintaining operational stability and equipment safety. To address these issues, this paper proposed a USV navigation attitude prediction method that integrates Unscented Kalman Filtering (UKF) with a digital twin model. First, a three-degree-of-freedom mathematical model is constructed based on the motion characteristics of the USV to establish an initial digital twin model. Then, the UKF algorithm is improved with a dynamic sliding window approach and integrated with real vessel experimental data to achieve dynamic model parameter updates, further enhancing prediction accuracy. The updated twin model is subsequently used for USV navigation attitude prediction. Experimental results demonstrate that this method significantly improves prediction accuracy and robustness, even under complex sea conditions and sensor data loss, providing crucial support for the safety and reliability of USV autonomous navigation. Full article

(This article belongs to the Section Ocean Engineering)

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18 pages, 8297 KiB

Open AccessArticle

Numerical Investigation of Jet Angle Effects on Thermal Dispersion Characteristics in Coastal Waters

by Longsheng Li, Hongyuan Shi, Huaiyuan Xue, Qing Wang and Chao Zhan

J. Mar. Sci. Eng. 2025, 13(5), 931; https://doi.org/10.3390/jmse13050931 - 9 May 2025

Abstract

Under the carbon neutrality framework, multiple coastal nuclear power plants in China have received construction approval. This development has drawn increased attention to the impact of thermal discharge on the marine environment. However, research on the diffusion effects caused by different thermal discharge [...] Read more.

Under the carbon neutrality framework, multiple coastal nuclear power plants in China have received construction approval. This development has drawn increased attention to the impact of thermal discharge on the marine environment. However, research on the diffusion effects caused by different thermal discharge configurations remains limited. This study focused on the Jinqimen Nuclear Power Plant. It employed the MIKE 3 (2014) three-dimensional numerical model, combined with field observations, to systematically investigate thermal plume dispersion. Specifically, it examined the effects of different jet angles at the discharge outlet (0°, 30°, 45°, 60°, 90°, and free diffusion conditions). The results indicate that the jet angle significantly influences the thermal rise envelope area and thermal stratification characteristics. Under free diffusion conditions (without jet velocity), the thermal rise area is the largest, with high-temperature zones concentrated near the surface. As the jet angle increases from 0° to 90°, the area of low-temperature rise gradually decreases, while the area of high-temperature rise expands. Among all tested configurations, the 30° jet angle exhibits the best overall performance. It demonstrates high thermal diffusion efficiency and strong heat dilution capacity. Moreover, it results in relatively smaller temperature rise areas at the surface, middle, and bottom layers. Additionally, tidal dynamics directly affect the thermal dispersion pattern. Smaller high-temperature rise areas are observed during peak flood and ebb tides. In contrast, heat accumulation is more likely to occur during slack tide periods. This study provides a scientific basis for optimizing the layout of nuclear power plant discharge outlets. It also serves as an important reference for mitigating thermal pollution and reducing ecological impacts of coastal nuclear power plants. Full article

(This article belongs to the Section Coastal Engineering)

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29 pages, 9843 KiB

Open AccessArticle

Coupled Response of Flexible Multi-Buoy Offshore Floating Photovoltaic Array Under Waves and Currents

by Xing-Hua Shi, Yiming Wang, Jing Zhang, C. Guedes Soares, Honglong Li and Jia Yu

J. Mar. Sci. Eng. 2025, 13(5), 930; https://doi.org/10.3390/jmse13050930 - 9 May 2025

Abstract

To study the response of a flexible offshore floating photovoltaic (FPV) array under waves and a current, a numerical model is established using OrcaFlex. The effects of different waves and currents, as well as their coupled effects on the motion response of the [...] Read more.

To study the response of a flexible offshore floating photovoltaic (FPV) array under waves and a current, a numerical model is established using OrcaFlex. The effects of different waves and currents, as well as their coupled effects on the motion response of the offshore PFV array and the tension in the connectors and moorings under different static tensions, are investigated. Differences are illustrated between the responses of the buoys at different positions and under different moorings under the wave. With the relaxed moorings, the surge response of the buoy facing the wave increased by 159.3% compared with the buoy facing away from the wave. The current causes the overall drift of the array, which greatly influences the buoys facing the current. The mooring tension facing the wave restricts the motion of the buoys under the same direction as the wave and current, which shows that the trend of the buoys’ responses with the wave decreases with the increase in the current velocity, as the pitch reduces to 76.9% under relaxed moorings. There is a significant difference between the results obtained by the superposition summation wave and current loads and the ones of the combined wave–current. With the increase in the wave–current angle, the response is increased by 348.2% as the constraint of the moorings and the connectors is weakened. Full article

(This article belongs to the Special Issue Development and Utilization of Offshore Renewable Energy)

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25 pages, 3951 KiB

Open AccessArticle

Port Green Transformation Factors Assessment

by Vytautas Paulauskas, Donatas Paulauskas and Antanas Markauskas

J. Mar. Sci. Eng. 2025, 13(5), 929; https://doi.org/10.3390/jmse13050929 - 9 May 2025

Abstract

The ambition of ports to become green and smart ports is one of the important ways to reduce environmental impacts and optimize energy consumption in passenger service and cargo handling operations in ports. One of the ways to transform a green port is [...] Read more.

The ambition of ports to become green and smart ports is one of the important ways to reduce environmental impacts and optimize energy consumption in passenger service and cargo handling operations in ports. One of the ways to transform a green port is to use renewable energy sources, more environmentally friendly fuels and reduce emissions in passenger service and cargo handling operations. The article analyses the main factors of green port transformation and factors assessment, including port strategy, port management, passenger service and cargo handling operations (port activity level), additional port services, and the activities of companies providing services to the port. Optimization of the indicated factors is important from the point of view of environmental sustainability. The article presents a methodology for direct and relative assessment of the current state of the green transformation and emissions generated in the port and options for reducing the environmental impact. This approach enables each port to evaluate its stage in the green transformation process and identify the primary emissions it produces. By understanding the actual state of green transformation, ports can identify the factors and measures necessary to improve their environmental performance and reduce their ecological footprint. The article presents a methodology for assessing green transformation and calculating both absolute and relative emissions, which can be adapted and applied to any port. Full article

(This article belongs to the Special Issue Maritime Logistics and Green Shipping)

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20 pages, 5879 KiB

Open AccessArticle

A High-Precision Method for Evaluating the Similarity of Maritime Vessel Trajectories

by Ran Ji, Mengkai Ma, Jian Dong and Sen Wang

J. Mar. Sci. Eng. 2025, 13(5), 928; https://doi.org/10.3390/jmse13050928 - 8 May 2025

Abstract

This study investigates the demand for high-precision trajectory similarity assessment in intelligent maritime navigation. This is done by analyzing discrepancies between GPS-derived trajectories and actual vessel paths, while identifying critical limitations in existing evaluation methods. To address these challenges, we propose a robust [...] Read more.

This study investigates the demand for high-precision trajectory similarity assessment in intelligent maritime navigation. This is done by analyzing discrepancies between GPS-derived trajectories and actual vessel paths, while identifying critical limitations in existing evaluation methods. To address these challenges, we propose a robust framework that integrates three core innovations: firstly, a linear feature accuracy-constrained resampling method to ensure computational precision under diverse complexity conditions, validated through experimental verification; secondly, a shape feature extraction and transformation protocol designed to maintain consistency across multi-scale and heterogeneous operational scenarios; thirdly, a quantitative similarity evaluation criterion based on extracted shape characteristics, enabling systematic alignment between localized trajectory segments and historical navigation patterns. The experimental results confirm the method’s enhanced robustness and its capability to bridge local and global trajectory comparisons, demonstrating that shape-driven quantification significantly refines similarity analysis. This approach advances intelligent maritime systems by providing a technically rigorous solution for real-time decision support and actionable insights into next-generation navigation applications. Full article

(This article belongs to the Section Ocean Engineering)

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16 pages, 3560 KiB

Open AccessArticle

Year-Round Acoustic Presence of Beaked Whales (Ziphiidae) Far Offshore off Australia’s Northwest Shelf

by Evgenii Sidenko, Iain Parnum, Alexander Gavrilov, Robert McCauley and Christine Erbe

J. Mar. Sci. Eng. 2025, 13(5), 927; https://doi.org/10.3390/jmse13050927 - 8 May 2025

Abstract

Beaked whales are a cryptic pelagic species, rarely sighted at sea. In a ~2.5-year passive acoustic monitoring program on Australia’s Northwest Shelf, a variety of marine mammal sounds were detected, including beaked whale (Ziphiidae) clicks. An automatic detection routine for beaked whale clicks [...] Read more.

Beaked whales are a cryptic pelagic species, rarely sighted at sea. In a ~2.5-year passive acoustic monitoring program on Australia’s Northwest Shelf, a variety of marine mammal sounds were detected, including beaked whale (Ziphiidae) clicks. An automatic detection routine for beaked whale clicks was developed, tested, and run on these recordings. The detection workflow included: (1) the extraction of impulsive signals from passive acoustic recordings based on an auto-regression model, (2) the calculation of a set of features of extracted signals, and (3) binary signal classification based on these features. Detector performance (Precision, Recall, and F1-score) was assessed using a manually annotated dataset of extracted clicks. This automated routine allows for quick analysis of animal (acoustic) presence and distribution spatially and temporally. In our study, beaked whales were present all year round at six deep-water (>1000 m) sites, but no clicks were detected at the shallow-water (~70 m) site. No seasonal or diurnal patterns of beaked whale clicks were identified. Full article

(This article belongs to the Special Issue Advances in Ecological Modelling of Marine Mammal Habitats of Importance)

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16 pages, 3414 KiB

Open AccessArticle

Underwater Side-Scan Sonar Target Detection: An Enhanced YOLOv11 Framework Integrating Attention Mechanisms and a Bi-Directional Feature Pyramid Network

by Junhui Zhu, Houpu Li, Min Liu, Guojun Zhai, Shaofeng Bian, Ye Peng and Lei Liu

J. Mar. Sci. Eng. 2025, 13(5), 926; https://doi.org/10.3390/jmse13050926 - 8 May 2025

Abstract

Underwater target detection is pivotal for marine exploration, yet it faces significant challenges because of the inherent complex underwater environment. Sonar images are generally degraded by noise, exhibit low resolution, and lack prominent target features, making the extraction of useful feature information from [...] Read more.

Underwater target detection is pivotal for marine exploration, yet it faces significant challenges because of the inherent complex underwater environment. Sonar images are generally degraded by noise, exhibit low resolution, and lack prominent target features, making the extraction of useful feature information from blurred and complex backgrounds particularly challenging. These limitations hinder highly accurate autonomous target detection in sonar imagery. To address these issues, this paper proposes the ABFP-YOLO model, which was designed to enhance the accuracy of underwater target detection. Specifically, the bi-directional feature pyramid network (BiFPN) structure is integrated into the model to efficiently fuse the features of different scales, significantly improving the capability of the network to recognize targets of varying scales, especially small targets in complex scenarios. Additionally, an attention module is incorporated to enhance feature extraction from blurred images, thereby boosting the detection accuracy of the model. To validate the proposed model’s effectiveness, extensive comparative and ablation experiments were conducted on two datasets. The experimental results demonstrate that the ABFP-YOLO model achieves mean average precision (mAP0.5) scores of 0.988 and 0.866, indicating its superior performance in target detection tasks within complex underwater environments. Full article

(This article belongs to the Section Ocean Engineering)

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21 pages, 5470 KiB

Open AccessArticle

YOLO-LPSS: A Lightweight and Precise Detection Model for Small Sea Ships

by Liran Shen, Tianchun Gao and Qingbo Yin

J. Mar. Sci. Eng. 2025, 13(5), 925; https://doi.org/10.3390/jmse13050925 - 8 May 2025

Abstract

The accurate detection of small ships based on images or vision is critical for many scenarios, like maritime surveillance, port security, and navigation safety. However, achieving accurate detection for small ships is a challenge for cost-efficiency models; while the models could meet this [...] Read more.

The accurate detection of small ships based on images or vision is critical for many scenarios, like maritime surveillance, port security, and navigation safety. However, achieving accurate detection for small ships is a challenge for cost-efficiency models; while the models could meet this requirement, they have unacceptable computation costs for real-time surveillance. We propose YOLO-LPSS, a novel model designed to significantly improve small ship detection accuracy with low computation cost. The characteristics of YOLO-LPSS are as follows: (1) Strengthening the backbone’s ability to extract and emphasize features relevant to small ship objects, particularly in semantic-rich layers. (2) A sophisticated, learnable method for up-sampling processes is employed, taking into account both deep image information and semantic information. (3) Introducing a post-processing mechanism in the final output of the resampling process to restore the missing local region features in the high-resolution feature map and capture the global-dependence features. The experimental results show that YOLO-LPSS outperforms the known YOLOv8 nano baseline and other works, and the number of parameters increases by only 0.33 M compared to the original YOLOv8n while achieving 0.796 and 0.831 AP^50:95 in classes consisting mainly of small ship targets (the bounding box of the target area is less than 5% of the image resolution), which is 3–5% higher than the vanilla model and recent SOTA models. Full article

(This article belongs to the Section Ocean Engineering)

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17 pages, 12491 KiB

Open AccessArticle

Hydrodynamic Analysis of Combined Offshore Wind Turbine and Net Cage Under Finite-Depth Waves

by Bin Wang, Mingfu Tang, Zhenqiang Jiang and Guohai Dong

J. Mar. Sci. Eng. 2025, 13(5), 924; https://doi.org/10.3390/jmse13050924 - 8 May 2025

Abstract

Offshore wind turbines are subjected to long-term wave loads, which shorten their service life. Marine aquaculture cages are common structures in the ocean engineering field. Therefore, investigating the hydrodynamic characteristics of combined wind turbine and cage facilities under wave loads is crucial. This [...] Read more.

Offshore wind turbines are subjected to long-term wave loads, which shorten their service life. Marine aquaculture cages are common structures in the ocean engineering field. Therefore, investigating the hydrodynamic characteristics of combined wind turbine and cage facilities under wave loads is crucial. This study employs a porous medium model to analyze the hydrodynamic behavior of a fixed wind turbine base integrated with cages under finite-depth wave conditions. First, the transmission coefficients of waves passing through cages at different positions were examined under varying cage solidity conditions. The results indicate that the cages minimally affect wave height in regions close to the cage group. Subsequently, the wave forces acting on the fixed wind turbine base behind the cages were analyzed under different solidity and wave height conditions. The variation curves of the drag coefficient and inertia coefficient were obtained for solidity values ranging from 0.3 to 0.6 and Keulegan–Carpenter (KC) numbers between 1 and 4. Full article

(This article belongs to the Section Ocean Engineering)

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18 pages, 6095 KiB

Open AccessArticle

Influence of Viscous Effects on Mooring Buoy Motion

by Yunmiao Li, Jian Zhou, Heping Wang and Chenxu Wang

J. Mar. Sci. Eng. 2025, 13(5), 923; https://doi.org/10.3390/jmse13050923 - 7 May 2025

Abstract

Field observations revealed that a mooring buoy rapidly drifts in a reciprocating motion along an arcuate path between two extreme positions. When the anchor point is considered the origin and viewed from an aerial perspective, this movement resembles a pendulum. The implications of [...] Read more.

Field observations revealed that a mooring buoy rapidly drifts in a reciprocating motion along an arcuate path between two extreme positions. When the anchor point is considered the origin and viewed from an aerial perspective, this movement resembles a pendulum. The implications of this motion for data acquisition efficiency prompted our inquiry into this phenomenon. The comparative analysis of the model’s different movements under wave-only, current-only, and wave–current conditions demonstrates that currents are the source inducing this pendulum-like motion. To investigate the mechanism of this current-driven motion, the flow field around the buoy was visualized through numerical simulations. Specifically, the CFD results aligned with the field data and confirmed that periodic vortex shedding induces oscillatory forces, which dominate the rapid reciprocating movement. The findings emphasize the significant impact of fluid viscosity and the resulting vortex effects on the motion characteristics of buoys. They can provide a foundation for addressing more applied problems of data error-correcting and trajectory predictions. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety—Second Edition)

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29 pages, 19185 KiB

Open AccessArticle

An AIS-Based Study to Estimate Ship Exhaust Emissions Using Spatio-Temporal Approach

by Akhahenda Whitney Khayenzeli, Woo-Ju Son, Dong-June Jo and Ik-Soon Cho

J. Mar. Sci. Eng. 2025, 13(5), 922; https://doi.org/10.3390/jmse13050922 - 7 May 2025

Abstract

The global shipping industry facilitates the movement of approximately 80% of goods across the world but accounts for nearly 3% of total greenhouse gas (GHG) emissions every year, and other pollutants. One challenge in reducing shipping emissions is understanding and quantifying emission characteristics. [...] Read more.

The global shipping industry facilitates the movement of approximately 80% of goods across the world but accounts for nearly 3% of total greenhouse gas (GHG) emissions every year, and other pollutants. One challenge in reducing shipping emissions is understanding and quantifying emission characteristics. A detailed method for calculating shipping emissions should be applied when preparing exhaust gas inventory. This research focused on quantifying CO₂, NO_x, and SO_x emissions from tankers, containers, bulk carriers, and general cargo in the Republic of Korea using spatio-temporal analysis and maritime big data. Using the bottom-up approach, this study calculates vessel emissions from the ship engines while considering the fuel type and operation mode. It leveraged the Geographic Information System (GIS) to generate spatial distribution maps of vessel exhausts. The research revealed variability in emissions according to ship types, sizes, and operational modes. CO₂ emissions were dominant, totaling 10.5 million tons, NO_x 179,355.2 tons, and SO_x 32,505.1 tons. Tankers accounted for about 43.3%, containers 33.1%, bulk carriers 17.3%, and general cargo 6.3%. Further, emissions in hoteling and cruising were more significant than during maneuvering and reduced speed zones (RSZs). This study contributes to emission databases, providing a basis for the establishment of targeted emission control policies. Full article

(This article belongs to the Special Issue Smart and Low Carbon Emission-Oriented Maritime Traffic Management and Controlling)

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16 pages, 31769 KiB

Open AccessArticle

Orbital-Scale Modulation of the Middle Miocene Third-Order Eustatic Sequences from the Northern South China Sea

by Haichun Xu, Nan Wu, Xinyan Xu, Bo Yu and Ke Xu

J. Mar. Sci. Eng. 2025, 13(5), 921; https://doi.org/10.3390/jmse13050921 - 7 May 2025

Abstract

The Miocene Hanjiang Formation (HJF) is a remarkable exploration target in the Pearl River Mouth Basin (PRMB). However, challenges such as bias in current sequence stratigraphic schemes, limitations in high-resolution stratigraphic schemes, and incomplete understanding of genetic mechanisms may present obstacles for refining [...] Read more.

The Miocene Hanjiang Formation (HJF) is a remarkable exploration target in the Pearl River Mouth Basin (PRMB). However, challenges such as bias in current sequence stratigraphic schemes, limitations in high-resolution stratigraphic schemes, and incomplete understanding of genetic mechanisms may present obstacles for refining hydrocarbon exploration strategies. This study integrates gamma ray (GR) logging data, lithological variations, sequence stratigraphy, and cyclostratigraphy to delineate connections between sequence stratigraphy and astronomical forcing. The analysis utilizes gamma-ray logging data from boreholes LFA (1250–1960 m) and LFB (1070–1955 m) in the HJF. We constructed an absolute astronomical time scale anchored at the HJF’s top boundary (10.221 ± 0.4 Ma), identifying 6 third-order sequences through detailed analysis. Notably, 18 long-eccentricity cycles (405 kyr) and distinctive 1.2-Myr obliquity modulation signals were detected in the stratigraphic record. Our study demonstrates distinct connection between third-order sequence boundaries and the 1.2-Myr obliquity cycles, congruent with both global eustatic sea-level fluctuations and regional sea-level changes in the PRMB. The integration of cyclostratigraphic methods with sequence stratigraphic analysis proves particularly valuable for objective stratigraphic subdivision and understanding third-order sequence evolution in the divergent continental margin settings of the South China Sea. This approach enhances temporal resolution on a regional scale while revealing astronomical forcing mechanisms governing sedimentary 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—2nd Edition)

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6 pages, 166 KiB

Open AccessEditorial

Autonomous Marine Vehicle Operations—2nd Edition

by Xiao Liang, Rubo Zhang and Xingru Qu

J. Mar. Sci. Eng. 2025, 13(5), 920; https://doi.org/10.3390/jmse13050920 - 7 May 2025

Abstract

In recent years, the field of autonomous marine vehicles has undergone remarkable advancements, with unmanned surface vehicles (USVs) and unmanned underwater vehicles (UUVs) demonstrating transformative potential for oceanographic exploration and marine applications [...] Full article

(This article belongs to the Special Issue Autonomous Marine Vehicle Operations—2nd Edition)

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