Journal of Marine Science and Engineering

22 pages, 7406 KiB

Open AccessArticle

Decarbonation Effects of Mainstream Dual-Fuel Power Schemes Focus on IMO Mandatory Regulation and LCA Method

by Zhanwei Wang, Shidong Fan and Zhiqiang Han

J. Mar. Sci. Eng. 2025, 13(5), 847; https://doi.org/10.3390/jmse13050847 - 24 Apr 2025

Recently, the IMO has completed the guidelines on the life cycle greenhouse gas intensity of marine fuels to accelerate the application of alternative fuels. Low-carbon fuels may persist for decades and have become a key transitional phase in replacing marine fuels. A more [...] Read more.

Recently, the IMO has completed the guidelines on the life cycle greenhouse gas intensity of marine fuels to accelerate the application of alternative fuels. Low-carbon fuels may persist for decades and have become a key transitional phase in replacing marine fuels. A more comprehensive methodology for evaluating the carbon emission levels of marine fuels was explored, and the carbon emissions and environmental impacts of a 150,000-ton shuttle tanker under 19 dual-fuel power scenarios were evaluated using the Energy Efficiency Design Index (EEDI) and life cycle assessment (LCA) method. The results show that liquefied natural gas (LNG) has a higher carbon control potential level compared to liquefied petroleum gas (LPG) and methanol (MeOH), while LPG is superior to MeOH based on EEDI evaluation. LCA analysis results show that MeOH (biomass) has the best carbon control potential considering the carbon emissions of the well-to-tank phase of the fuel, followed by LNG, LPG, MeOH (natural gas, NG), and MeOH (coal). However, MeOH (NG) and MeOH (coal) had greater negative environmental impacts. This study provides method support and a direction toward improvement for revising related technical specifications and regulations for dual-fuel vessel performance evaluation, considering the limitations of various maritime regulations. Full article

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

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19 pages, 917 KiB

Open AccessArticle

Neural Unilateral Nussbaum Gain Sliding Mode Control for Uncertain Ship Course Keeping with an Unknown Control Direction

by Guoxin Ma, Dongliang Li, Qiang Wei and Lei Song

J. Mar. Sci. Eng. 2025, 13(5), 846; https://doi.org/10.3390/jmse13050846 - 24 Apr 2025

Abstract

This paper focuses on the ship control system and studies the problem of unknown control directions. Considering that the traditional Nussbaum gain method has to consider the complex situation where the gain converges to both positive and negative infinity when proving the stability [...] Read more.

This paper focuses on the ship control system and studies the problem of unknown control directions. Considering that the traditional Nussbaum gain method has to consider the complex situation where the gain converges to both positive and negative infinity when proving the stability of a system, a unilateral Nussbaum function is defined in this paper. By constructing this function, the design and proof process of the adaptive Nussbaum gain method are simplified. Taking the ship course–keeping control system as the research object, a course angle tracking controller is designed by combining neural network, robust adaptive, and sliding mode control techniques. A dual-input RBF single-output neural network is used to approximate the uncertain part of the system, and the robust adaptive control is adopted to deal with the unknown disturbance. The simulation results at the end of the article show that when the direction suddenly switches, the overshoot of the system reaches 40%, and the adjustment time is approximately 3 s. However, the system can still adapt to the change of the control direction and maintain stability, indicating that the method proposed in this paper is reasonable and effective. And the proposed method can effectively cope with the problems of the unknown control direction and its jump, keeping the system stable, which has great theoretical and engineering application value. Full article

(This article belongs to the Special Issue Autonomous Marine Vehicle Operations—3rd Edition)

20 pages, 7057 KiB

Open AccessArticle

Research on Particle Motion Characteristics in a Spiral-Vane-Type Multiphase Pump Based on CFD-DEM

by Guangtai Shi, Xi Yang, Binyan Li, Hongqiang Chai and Hao Qin

J. Mar. Sci. Eng. 2025, 13(5), 845; https://doi.org/10.3390/jmse13050845 - 24 Apr 2025

Abstract

In oil–gas mixed transportation using spiral-vane-type multiphase pumps, high sand content often causes wear on flow-passing components. To reveal the motion patterns of particles, a three-stage spiral-vane-type multiphase pump was selected as the research subject. A visualization test bench was constructed, and the [...] Read more.

In oil–gas mixed transportation using spiral-vane-type multiphase pumps, high sand content often causes wear on flow-passing components. To reveal the motion patterns of particles, a three-stage spiral-vane-type multiphase pump was selected as the research subject. A visualization test bench was constructed, and the pump’s performance curve was obtained by experimental measurements. High-speed photography was used to capture the flow process of a single particle within the pump, and CFD-DEM was used to study the motion characteristics of four particle sizes (0.5 mm, 1 mm, 1.5 mm, and 2 mm). The results showed that 0.5 mm and 1 mm particles had smaller trajectory angles in the guide vanes, while 1.5 mm and 2 mm particles had larger angles, with wall collisions observed. Velocity changes were similar: When they just enter the impeller, the circumferential velocity increases sharply and then stabilizes around 15 m/s. After entering the guide vane passage, the circumferential velocity exhibits an initial abrupt decrease followed by a gradual reduction. The axial velocity increases gradually along the impeller passage, reaches the highest value at the impeller outlet, and begins to decrease gradually after entering the guide vane. The particles had higher volume fractions in the guide vane and collided more with impeller walls. Collisions with guide vane walls increased with particle size. Full article

(This article belongs to the Section Ocean Engineering)

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28 pages, 1596 KiB

Open AccessArticle

Uncertain Parameters Adjustable Two-Stage Robust Optimization of Bulk Carrier Energy System Considering Wave Energy Utilization

by Weining Zhang, Chunteng Bao and Jianting Chen

J. Mar. Sci. Eng. 2025, 13(5), 844; https://doi.org/10.3390/jmse13050844 - 24 Apr 2025

Abstract

Abstract: Within the 21st century, in the Maritime Silk Road, wave energy, a clean renewable source, is drawing more interest, especially in areas with power shortages. This paper investigates wave energy in ships, particularly in a hybrid electric bulk carrier, by designing [...] Read more.

Abstract: Within the 21st century, in the Maritime Silk Road, wave energy, a clean renewable source, is drawing more interest, especially in areas with power shortages. This paper investigates wave energy in ships, particularly in a hybrid electric bulk carrier, by designing a system that supplements the existing power setup with oscillating buoy wave energy converters. The system includes diesel generators (DGs), a wave energy generation system, heterogeneous energy storage (consisting of battery storage (BS) and thermal storage (TS)), a combined cooling heat and power (CCHP) unit, and a power-to-thermal conversion (PtC) unit. To ensure safe and reliable navigation despite uncertainties in wave energy output, onboard power loads, and outdoor temperature, a robust coordination method is adopted. This method employs a two-stage robust optimization (RO) strategy to coordinate the various onboard units across different time scales, minimizing operational costs while satisfying all operational constraints, even in the worst-case scenarios. By applying constraint linearization, the robust coordination model is formulated as a mixed-integer linear programming (MILP) problem and solved using an efficient solver. Finally, the effectiveness of the proposed method is validated through case studies and comparisons with existing ship operation benchmarks, demonstrating significant reductions in operational costs and robust performance under various uncertain conditions. Notably, the simulation results for the Singapore–Trincomalee route show an 18.4% reduction in carbon emissions compared to conventional systems. Full article

(This article belongs to the Section Ocean Engineering)

23 pages, 10158 KiB

Open AccessArticle

Navigation and Obstacle Avoidance for USV in Autonomous Buoy Inspection: A Deep Reinforcement Learning Approach

by Jianhui Wang, Zhiqiang Lu, Xunjie Hong, Zeye Wu and Weihua Li

J. Mar. Sci. Eng. 2025, 13(5), 843; https://doi.org/10.3390/jmse13050843 - 24 Apr 2025

Abstract

To address the challenges of manual buoy inspection, this study enhances a previously proposed Unmanned Surface Vehicle (USV) inspection system by improving its navigation and obstacle avoidance capabilities using Proximal Policy Optimization (PPO). For improved usability, the entire system adopts a fully end-to-end [...] Read more.

To address the challenges of manual buoy inspection, this study enhances a previously proposed Unmanned Surface Vehicle (USV) inspection system by improving its navigation and obstacle avoidance capabilities using Proximal Policy Optimization (PPO). For improved usability, the entire system adopts a fully end-to-end design, with an angular deviation weighting mechanism for stable circular navigation, a novel image-based radar encoding technique for obstacle perception and a decoupled navigation and obstacle avoidance architecture that splits the complex task into three independently trained modules. Experiments validate that both navigation modules exhibit robustness and generalization capabilities, while the obstacle avoidance module partially achieves International Regulations for Preventing Collisions at Sea (COLREGs)-compliant maneuvers. Further tests in continuous multi-buoy inspection tasks confirm the architecture’s effectiveness in integrating these modules to complete the full task. Full article

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

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25 pages, 7765 KiB

Open AccessArticle

A Novel Swin-Transformer with Multi-Source Information Fusion for Online Cross-Domain Bearing RUL Prediction

by Zaimi Xie, Chunmei Mo and Baozhu Jia

J. Mar. Sci. Eng. 2025, 13(5), 842; https://doi.org/10.3390/jmse13050842 - 24 Apr 2025

Abstract

Accurate remaining useful life (RUL) prediction of rolling bearings plays a critical role in predictive maintenance. However, existing methods face challenges in extracting and fusing multi-source spatiotemporal features, addressing distribution differences between intra-domain and inter-domain features, and balancing global-local feature attention. To overcome [...] Read more.

Accurate remaining useful life (RUL) prediction of rolling bearings plays a critical role in predictive maintenance. However, existing methods face challenges in extracting and fusing multi-source spatiotemporal features, addressing distribution differences between intra-domain and inter-domain features, and balancing global-local feature attention. To overcome these limitations, this paper proposes an online cross-domain RUL prediction method based on a swin-transformer with multi-source information fusion. The method uses a Bidirectional Long Short-Term Memory (Bi-LSTM) network to capture temporal features, which are transformed into 2D images using Gramian Angular Fields (GAF) for spatial feature extraction by a 2D Convolutional Neural Network (CNN). A self-attention mechanism further integrates multi-source features, while an adversarial Multi-Kernel Maximum Mean Discrepancy (MK-MMD) combined with a relational network mitigates feature distribution differences across domains. Additionally, an offline-online swin-transformer with a dynamic weight updating strategy enhances cross-domain feature learning. Experimental results demonstrate that the proposed method significantly reduces Root Mean Square Error (RMSE) and Mean Absolute Error (MAE), outperforming public methods in prediction accuracy and robustness. Full article

(This article belongs to the Special Issue Ship Wireless Sensor)

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25 pages, 20571 KiB

Open AccessArticle

Mid-Water Ocean Current Field Estimation Using Radial Basis Functions Based on Multibeam Bathymetric Survey Data for AUV Navigation

by Jiawen Liu, Kaixuan Wang, Shuai Chang and Lin Pan

J. Mar. Sci. Eng. 2025, 13(5), 841; https://doi.org/10.3390/jmse13050841 - 24 Apr 2025

Abstract

Autonomous Underwater Vehicle (AUV) navigation relies on bottom-tracking velocity from Doppler Velocity Log (DVL) for positioning through dead-reckoning or aiding Strapdown Inertial Navigation System (SINS). In mid-water environments, the distance between the AUV and the seafloor exceeds the detection range of DVL, causing [...] Read more.

Autonomous Underwater Vehicle (AUV) navigation relies on bottom-tracking velocity from Doppler Velocity Log (DVL) for positioning through dead-reckoning or aiding Strapdown Inertial Navigation System (SINS). In mid-water environments, the distance between the AUV and the seafloor exceeds the detection range of DVL, causing failure of bottom-tracking and leaving only water-relative velocity available. This makes unknown ocean currents a significant error source that leads to substantial cumulative positioning errors. This paper proposes a method for mid-water ocean current estimation using multibeam bathymetric survey data. First, the method models the regional unknown current field using radius basis functions (RBFs) and establishes an AUV dead-reckoning model incorporating the current field. The RBF model inherently satisfies ocean current incompressibility. Subsequently, by dividing the multibeam bathymetric point cloud data surveyed by the AUV into submaps and performing a terrain-matching algorithm, relative position observations among different AUV positions can be constructed. These observations are then utilized to estimate the RBF parameters of the current field within the navigation model. Numerical simulations and experiments based on real-world bathymetric and ocean current data demonstrate that the proposed method can effectively capture the complex spatial variations in ocean currents, contributing to the accurate reconstruction of the mid-water current field and significant improvement in positioning accuracy. Full article

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

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19 pages, 3436 KiB

Open AccessArticle

Underwater Target 3D Reconstruction via Integrated Laser Triangulation and Multispectral Photometric Stereo

by Yang Yang, Yimei Liu, Eric Rigall, Yifan Yin, Shu Zhang and Junyu Dong

J. Mar. Sci. Eng. 2025, 13(5), 840; https://doi.org/10.3390/jmse13050840 - 24 Apr 2025

Abstract

With the gradual application of 3D reconstruction technology in underwater scenes, the design of vision-based reconstruction models has become an important research direction for human ocean exploration and development. The underwater laser triangulation method is the most commonly used approach, yet it misses [...] Read more.

With the gradual application of 3D reconstruction technology in underwater scenes, the design of vision-based reconstruction models has become an important research direction for human ocean exploration and development. The underwater laser triangulation method is the most commonly used approach, yet it misses details during the reconstruction of sparse point clouds, which do not meet the requirements of practical applications. On the other hand, existing underwater photometric stereo methods can accurately reconstruct local details of target objects, but they require relative stillness to be maintained between the camera and the target, which is practically difficult to achieve in underwater imaging environments. In this paper, we propose an underwater target reconstruction algorithm that combines laser triangulation and multispectral photometric stereo (MPS) to address the aforementioned practical problems in underwater 3D reconstruction.This algorithm can obtain more comprehensive 3D surface data of underwater objects through mobile measurement. At the same time, we propose to optimize the laser place calibration and laser line separation processes, further improving the reconstruction performance of underwater laser triangulation and multispectral photometric stereo. The experimental results show that our method achieves higher-precision and higher-density 3D reconstruction than current state-of-the-art methods. Full article

(This article belongs to the Section Ocean Engineering)

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30 pages, 2293 KiB

Open AccessReview

Green Technologies for Environmental Air and Water Impact Reduction in Ships: A Systematic Literature Review

by Edwin Paipa-Sanabria, Daniel González-Montoya and Jairo R. Coronado-Hernández

J. Mar. Sci. Eng. 2025, 13(5), 839; https://doi.org/10.3390/jmse13050839 - 24 Apr 2025

Abstract

This study reviews various green technological strategies integrated into vessels to mitigate environmental impact, focusing on atmospheric pollution and marine environment protection. The research is based on a systematic review of academic literature published between 2019 and 2024, using the Scopus and Web [...] Read more.

This study reviews various green technological strategies integrated into vessels to mitigate environmental impact, focusing on atmospheric pollution and marine environment protection. The research is based on a systematic review of academic literature published between 2019 and 2024, using the Scopus and Web of Science databases and applying PRISMA criteria. The findings reveal that the main environmental issues in the naval sector include greenhouse gas emissions, harmful discharges, and invasive species that affect marine biodiversity. The analysis is framed within international regulations such as those established by the IMO and classification societies, where the most relevant indicators identified are the EEDI and EEXI. However, the results of this review emphasize that, while these regulations are fundamental, it is necessary to analyze further the technical and economic barriers affecting the widespread implementation of these technologies and develop incentive mechanisms that facilitate their adoption across different vessel types and sizes. Promising solutions include alternative fuels, new propulsion systems, and emission-reduction technologies. The conclusion underlines that although the sector is transitioning toward sustainability, economic and widespread implementation challenges remain. Full article

(This article belongs to the Topic Conservation and Management of Marine Ecosystems)

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15 pages, 6956 KiB

Open AccessArticle

Investigation of Typhoon-Induced Wind Waves for Deep-Sea Wind Power Platform Design

by Jianjun Yi, Guangpu Bai, Pengfei Li and Jia Sun

J. Mar. Sci. Eng. 2025, 13(5), 838; https://doi.org/10.3390/jmse13050838 - 23 Apr 2025

Abstract

Typhoons generate extreme waves that pose significant threats to offshore wind power platforms in deep-sea areas, a challenge not fully addressed in current design standards. This study investigates wind–wave coupling processes during typhoon events to provide guidance for typhoon selection in deep-sea wind [...] Read more.

Typhoons generate extreme waves that pose significant threats to offshore wind power platforms in deep-sea areas, a challenge not fully addressed in current design standards. This study investigates wind–wave coupling processes during typhoon events to provide guidance for typhoon selection in deep-sea wind power platform design. Using Pearson Type III frequency analysis of typhoon data from 1949 to 2019, the 50-year return period typhoon intensity was determined for the study area. The validated SWAN model was employed to simulate typhoon-induced waves, revealing that wave height contours align parallel to the coastline and increase sharply from nearshore to deep-sea areas. The maximum significant wave height reaches 7.78 m when a 50-year return period typhoon passes the engineering site. These findings offer critical insights for offshore wind farm design in typhoon-prone regions, providing a robust basis for wave load assessment, structural fatigue analysis, and safety optimization. Full article

(This article belongs to the Section Coastal Engineering)

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26 pages, 14600 KiB

Open AccessArticle

Hydrodynamic Study of a Fall Pipe Rock Dumping System

by Mingjiu Zuo, Xinyi Zhou, Haiwen Tu, Zehui Liang, Yan Wei, Kai Xia, Haodi Zhu, Haibin Han, Jiayi Su and Fengzhong Qu

J. Mar. Sci. Eng. 2025, 13(5), 837; https://doi.org/10.3390/jmse13050837 - 23 Apr 2025

Abstract

The fall pipe rock dumping technique is extensively employed to create protection embankments around submarine cables, mitigating distortion and breakage resulting from bottom scouring. During the rock dumping operation, intricate interactions among the pipeline, rocks, and water currents can affect the stability and [...] Read more.

The fall pipe rock dumping technique is extensively employed to create protection embankments around submarine cables, mitigating distortion and breakage resulting from bottom scouring. During the rock dumping operation, intricate interactions among the pipeline, rocks, and water currents can affect the stability and efficiency of the fall pipe system. This research proposed a method employing the fluid–structure interaction to analyze the interactions between the pipeline, rocks, and water currents. The paper begins with the design of an innovative fall pipe rock dumping system and presents a theoretical analysis of the applied model testing approach. The simulation parameters were determined according to the geometric, Froude, and Strouhal similarity criteria. A thorough numerical analysis was performed to investigate the hydrodynamic properties of the rockfall pipeline under fluid–structure interaction. The research examined the settling of rocks during rockfall, along with the forces and movements associated with the deposition process. The results show that the rockfall pipeline experienced vortex-induced vibrations (VIVs) caused by ocean currents during operation. The maximum settling velocity of the rocks throughout the rockfall process reached 2.2 m/s, with a final stable velocity of 1.5 m/s. These simulation results offer critical insights for improving the design and functionality of the rockfall pipeline, thereby enhancing the protection of underwater infrastructure. Full article

(This article belongs to the Section Ocean Engineering)

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20 pages, 5434 KiB

Open AccessArticle

Ecological Responses of Microbially Activated Water Flooding in Ultra-Low-Permeability Reservoirs: A Case Study of the B9 Reservoir in the Triassic Yanchang Formation

by Lei Li, Chunhui Zhang, Peidong Su and Hongmei Mu

J. Mar. Sci. Eng. 2025, 13(5), 836; https://doi.org/10.3390/jmse13050836 - 23 Apr 2025

Abstract

The impact of anthropogenic disturbances during reservoir development on the ecological system—encompassing both environmental and microbial components—has long been overlooked. This study pioneers the investigation into the effects of microbially activated water flooding on both reservoir environments and indigenous microbial communities. We conducted [...] Read more.

The impact of anthropogenic disturbances during reservoir development on the ecological system—encompassing both environmental and microbial components—has long been overlooked. This study pioneers the investigation into the effects of microbially activated water flooding on both reservoir environments and indigenous microbial communities. We conducted a comprehensive analysis of the B9 Reservoir’s parameters before and after field testing, including the pH, redox potential, conductivity, chemical oxygen demand, biochemical oxygen demand, aqueous-phase cell concentration, aqueous-phase deoxyribonucleic acid (DNA) concentration, oil-phase DNA concentration, and microbial population data. The results demonstrate that environmental parameters exhibit high sensitivity to microbially activated water flooding and effectively explain microbial blooms, while microbial blooms reciprocally alter the environmental conditions, forming a mutually influencing dynamic interplay. The 183-day microbially activated water flooding, while causing detectable impacts on the reservoir environment and microorganisms, did not pose a threat to its ecological stability and contributed to enhanced oil production. In contrast, the 60-month pilot test concluded 27 months earlier exhibited potential destabilization risks to the reservoir ecology. By simultaneously monitoring reservoir environments and microbial dynamics, this research not only addresses potential ecological risks associated with human-driven reservoir development but also provides actionable insights to optimize reservoir management strategies. Full article

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18 pages, 5557 KiB

Open AccessArticle

The Phytoplankton Community Exhibited Restored Species Diversity but Fragile Network Stability Under Potential Sustainable Aquaculture Approach of Marine Ranching

by Dongqun Wei, Zeping Xie, Jialin Li, Diansheng Ji, Lin Qu, Baoquan Li, Xiao Wei and Song Qin

J. Mar. Sci. Eng. 2025, 13(5), 835; https://doi.org/10.3390/jmse13050835 - 23 Apr 2025

Abstract

Mariculture is currently experiencing rapid growth in response to the rising global food demand, while simultaneously posing significant challenges to environmental issues, such as pollution stress and ecological degradation. To achieve a balance between ecosystem maintenance and seafood supply, marine ranching has flourished [...] Read more.

Mariculture is currently experiencing rapid growth in response to the rising global food demand, while simultaneously posing significant challenges to environmental issues, such as pollution stress and ecological degradation. To achieve a balance between ecosystem maintenance and seafood supply, marine ranching has flourished as a sustainable approach through the implementation of artificial reef construction, stock enhancement, and strategic releasing. However, few studies have evaluated the ecological impacts through a comparison of in situ survey data across geographical areas. Phytoplankton are vital organisms in marine ecosystems that function as essential indicators of seawater quality and biological diversity, reflecting environmental health and ecological sustainability. In this study, we investigated the species diversity, community structure, and co-occurrence network of phytoplankton based on 175 samples collected from 75 sites encompassing all 26 marine ranching seawater areas, along with their corresponding surrounding areas in Yantai’s coastal sea. A total of 112 species were identified across three phyla of diatoms, dinoflagellates, and chrysophytes; among them, diatoms dominated the community with a notably high proportion of 98.83%. Their diversity and structure exhibited significant variations across different seasons and geographic locations. Moreover, no preference was observed between the marine ranching seawater and the surrounding areas. Nevertheless, a co-occurrence network analysis demonstrated that lower values for average degree, clustering coefficient, and average path length were exhibited in marine ranching, indicating that aquaculture activities have reduced connectivity among potential interactions. Additionally, it showed reduced stability as indicated by the remaining nodes and the natural connectivity indices, regardless of the proportion of nodes removed. These findings illustrate that while marine ranching processes can mitigate species losses with maintaining phytoplankton community structure, they still alter association among species and reduce overall stability. This research recommends that scientifically informed expansion of marine ranching necessitates robust environmental monitoring datasets and systematic validation to ensure holistic sustainability. Full article

(This article belongs to the Special Issue Plankton Community in Marine Ecological Environment: Latest Advances and Prospects)

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Graphical abstract

17 pages, 6370 KiB

Open AccessArticle

Derivation of the Controllable Region for Attitude Control of Towfish and Verification Through Water Tank Test

by Jihyeong Lee and Min-Kyu Kim

J. Mar. Sci. Eng. 2025, 13(5), 834; https://doi.org/10.3390/jmse13050834 - 23 Apr 2025

Abstract

We investigated the attitude control of a towfish to enhance the image quality of its sound navigation ranging system. The target towfish is equipped with two elevators on the horizontal tail wing, and attitude control is performed using these actuators. In particular, when [...] Read more.

We investigated the attitude control of a towfish to enhance the image quality of its sound navigation ranging system. The target towfish is equipped with two elevators on the horizontal tail wing, and attitude control is performed using these actuators. In particular, when a high-resolution sonar system is mounted on the towfish, any irregular movement can cause defocusing; thus, attitude control of the towfish is essential. Because the towfish has no thrust of its own and moves by being connected to a mother vessel via a cable, its attitude must be controlled by comprehensively analyzing its towing force and equation of motion. Herein, we propose a method for calculating the region where the attitude of the towfish can be controlled based on changes in the center of gravity, towing speed, and towing point. We conducted a water tank test to verify this method and confirmed that the attitude of the towfish could be controlled in controllable areas but not in uncontrollable regions. Full article

(This article belongs to the Special Issue Models and Simulations of Ship Manoeuvring)

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19 pages, 4008 KiB

Open AccessArticle

Relative Localization and Dynamic Tracking of Underwater Robots Based on 3D-AprilTag

by Guoqiang Tang, Tengfei Yang, Yan Yang, Qiang Zhao, Minyi Xu and Guangming Xie

J. Mar. Sci. Eng. 2025, 13(5), 833; https://doi.org/10.3390/jmse13050833 - 23 Apr 2025

Abstract

This paper presents a visual localization system for underwater robots, aimed at achieving high-precision relative positioning and dynamic target tracking. A 3D AprilTag reference structure is constructed using a cubic configuration, and a high-resolution camera module is integrated into the AUV for real-time [...] Read more.

This paper presents a visual localization system for underwater robots, aimed at achieving high-precision relative positioning and dynamic target tracking. A 3D AprilTag reference structure is constructed using a cubic configuration, and a high-resolution camera module is integrated into the AUV for real-time tag detection and pose decoding. By combining multi-face marker geometry with a fused state estimation strategy, the proposed method improves pose continuity and robustness during multi-tag transitions. To address pose estimation discontinuities caused by viewpoint changes and tag switching, we introduce a fusion-based observation-switching Kalman filter, which performs weighted integration of multiple tag observations based on relative distance, viewing angle, and detection confidence, ensuring smooth pose updates during tag transitions. The experimental results demonstrate that the system maintains stable pose estimation and trajectory continuity even under rapid viewpoint changes and frequent tag switches. These results validate the feasibility and applicability of the proposed method for underwater relative localization and tracking tasks. Full article

(This article belongs to the Section Ocean Engineering)

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18 pages, 13190 KiB

Open AccessArticle

Evolution of Stratigraphic Sequence and Sedimentary Environment in Northern Yellow River Delta Since MIS5

by Haonan Li, Guangxue Li, Jian Zhang, Jiejun Yang, Lvyang Xing, Wenyu Ji and Siyu Liu

J. Mar. Sci. Eng. 2025, 13(5), 832; https://doi.org/10.3390/jmse13050832 - 23 Apr 2025

Abstract

Quaternary climate has been characterized by pronounced glacial–interglacial cycles, with eustatic sea-level fluctuations directly controlling coastal sedimentary environments. The Yellow River Delta, situated on the southwestern coast of Bohai Bay, bears a distinct stratigraphic imprint of marine–terrestrial environmental transitions. However, critical knowledge gaps [...] Read more.

Quaternary climate has been characterized by pronounced glacial–interglacial cycles, with eustatic sea-level fluctuations directly controlling coastal sedimentary environments. The Yellow River Delta, situated on the southwestern coast of Bohai Bay, bears a distinct stratigraphic imprint of marine–terrestrial environmental transitions. However, critical knowledge gaps persist in reconstructing an integrated continental–marine stratigraphic framework. This study focuses on the nearshore core CB2302, integrating sediment lithology, grain size, foraminiferal assemblages, and geochemical proxies to establish a regional stratigraphic chronology since MIS5. Three depositional units (DU1–DU3) and 12 sedimentary subunits (C1–C12) were identified based on grain-size distributions, geochemical signatures, hydrodynamic, and microfossil assemblages. Integration of AMS ¹⁴C dating and sequence stratigraphic analysis establishes a post-MIS 5 stratigraphic framework for the northern Yellow River Delta, revealing sedimentary responses to three transgressive–regressive cycles (MIS 5e, 5c, and 5a) and confirming widespread terrestrial deposition during MIS 4–2, with no detectable marine influence in MIS 3 strata. Furthermore, correlation with representative cores across the Yellow–Bohai Sea coastal system elucidates a unified model of shoreline migration patterns driven by post-MIS5 sea-level oscillations. These findings advance the understanding of Quaternary sediment–landscape interactions in deltaic systems and provide critical stratigraphic benchmarks for petroleum exploration and coastal engineering in active depositional basins. Full article

(This article belongs to the Section Geological Oceanography)

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16 pages, 3046 KiB

Open AccessArticle

An Approach to Optimize the Efficiency of an Air Turbine of an Oscillating Water Column Based on Adaptive Model Predictive Control

by Yan Huang, Weixun Dong, Jianyu Fan, Shaohui Yang, Zhichang Du, Yongqiang Tu, Chenglong Li and Beichen Lin

J. Mar. Sci. Eng. 2025, 13(5), 831; https://doi.org/10.3390/jmse13050831 - 23 Apr 2025

Abstract

Wave energy, as a vast renewable resource, remains underutilized despite its high potential. The oscillating water column (OWC) is one of the most efficient way to harvest wave energy. Due to the randomness of ocean wave excitation, a control strategy is needed to [...] Read more.

Wave energy, as a vast renewable resource, remains underutilized despite its high potential. The oscillating water column (OWC) is one of the most efficient way to harvest wave energy. Due to the randomness of ocean wave excitation, a control strategy is needed to keep the conversion efficiency of OWC at a certain level. In this paper, an adaptive model predictive control (AMPC) method is proposed to optimize the efficiency of the air turbine and improve the overall efficiency of the OWC. Experiments were conducted in a wave flume to obtain realistic wave data, which were fed into the AMPC model for simulations. Results indicate that AMPC-optimized turbine efficiency exhibits improved performance under regular wave conditions and significantly enhances efficiency within certain intervals under short-period irregular waves. However, as the wave period increases, optimization becomes less stable. Overall, the study concludes that the adaptive MPC model effectively optimizes turbine efficiency under most conditions, highlighting its potential for enhancing OWC performance. Full article

(This article belongs to the Section Marine Energy)

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25 pages, 8161 KiB

Open AccessArticle

Numerical Study on the Influence of Rudder Fillets on Submarine Wake Field and Noise Characteristics

by Hao Yuan, Eryun Chen, Xingsheng Liu and Ailing Yang

J. Mar. Sci. Eng. 2025, 13(5), 830; https://doi.org/10.3390/jmse13050830 - 22 Apr 2025

Abstract

The submarine rudder configuration and arrangement significantly impact its hydrodynamic performance. This paper takes the SUBOFF standard submarine model as the research object, constructs a geometrically parameterized rudder fillet structure based on parabolic parametric equations, and adopts the improved delayed separation vortex (IDDES) [...] Read more.

The submarine rudder configuration and arrangement significantly impact its hydrodynamic performance. This paper takes the SUBOFF standard submarine model as the research object, constructs a geometrically parameterized rudder fillet structure based on parabolic parametric equations, and adopts the improved delayed separation vortex (IDDES) turbulence model to carry out numerical simulation research on the submarine rounding flow field with crossed and “X” rudder configurations. By comparing and analyzing the effects of different fillet parameters and rudder layouts on the generation mechanism of the horseshoe vortex, vortex system strength characteristics, and the distribution of the wake companion flow field at the velocity of 7.161 m/s, it is found that the introduction of the rudder fillet structure can effectively destabilize the horseshoe vortex and significantly reduce the axial velocity inhomogeneity of propeller plane. In addition, the improvement effect of the flow field in the near-axis region (r/R ∈ (0, 0.5)) is particularly significant. Compared with the crossed rudder, the “X” layout shows better flow control performance, with the maximum reduction in the axial relative velocity of the propeller plane surface reaching 49.34%, which is 24.25% higher than that of the SUBOFF baseline model, and the addition of two distributions of rudder fillets can reduce the hydrodynamic noise of the submarine by 4.6 dB vs. 5.6 dB at most. The results provide an essential hydrodynamic basis for optimizing the submarine rudder system. Full article

(This article belongs to the Section Ocean Engineering)

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30 pages, 11394 KiB

Open AccessArticle

Gap Impact on Rigid Submerged Vegetated Flow and Its Induced Flow Turbulence

by Heba Mals, Jaan H. Pu, Prashanth Reddy Hanmaiahgari, Bimlesh Kumar, Ebrahim Hamid Hussein Al-Qadami and Mohd Adib Mohammad Razi

J. Mar. Sci. Eng. 2025, 13(5), 829; https://doi.org/10.3390/jmse13050829 - 22 Apr 2025

Abstract

Submerged vegetation plays a crucial role in influencing flow hydrodynamics, generating turbulence, and shaping velocity distributions in aquatic environments. This study investigates the hydrodynamic effects of submerged rigid vegetation, specifically focusing on the local flow and turbulence alterations resulting from the removal of [...] Read more.

Submerged vegetation plays a crucial role in influencing flow hydrodynamics, generating turbulence, and shaping velocity distributions in aquatic environments. This study investigates the hydrodynamic effects of submerged rigid vegetation, specifically focusing on the local flow and turbulence alterations resulting from the removal of a single stem from an otherwise uniform vegetation array under controlled laboratory conditions. Experiments were conducted in a flume using Acoustic Doppler Velocimetry (ADV) to measure 3D (three-dimensional) flow characteristics, turbulence intensities, Reynolds shear stress (RSS), and quadrant analysis. In the fully vegetated scenario, vegetation significantly modified flow conditions, creating inflexion points and distinct peaks in velocity profiles, turbulence intensity, and RSS—particularly near two-thirds of the vegetation height—due to wake vortices and flow separation. The removal of a single stem introduced a localised gap, which redistributed turbulent energy, increased RSS and near-bed turbulent interactions, and disrupted the organised vortex structures downstream. While sweep and ejection events near the gap reached magnitudes similar to those in the fully vegetated setup, they lacked the characteristic coherent peaks linked to vortex generation. Overall, turbulence intensities and RSS were reduced, indicating a smoother flow regime and weaker energy redistribution mechanisms. These findings critically impact river restoration, flood management, and habitat conservation. By understanding how vegetation gaps alter flow hydrodynamics, engineers and ecologists can optimise vegetation placement in waterways to enhance flow efficiency, sediment transport, and aquatic ecosystem stability. This study bridges fundamental fluid mechanics with real-world applications in environmental hydraulics. Full article

(This article belongs to the Special Issue Hydrodynamic Response to the Effect of Current Loads on Floating Offshore Platform)

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