Journal of Marine Science and Engineering

19 pages, 4019 KiB

Open AccessArticle

Vessel Trajectory Prediction Based on Automatic Identification System Data: Multi-Gated Attention Encoder Decoder Network

by Fan Yang, Chunlin He, Yi Liu, Anping Zeng and Longhe Hu

J. Mar. Sci. Eng. 2024, 12(10), 1695; https://doi.org/10.3390/jmse12101695 - 24 Sep 2024

Abstract

Utilizing time-series data from ship trajectories to forecast their subsequent movement is crucial for enhancing the safety within maritime traffic environments. The application of deep learning techniques, leveraging Automatic Identification System (AIS) data, has emerged as a pivotal area in maritime traffic studies. [...] Read more.

Utilizing time-series data from ship trajectories to forecast their subsequent movement is crucial for enhancing the safety within maritime traffic environments. The application of deep learning techniques, leveraging Automatic Identification System (AIS) data, has emerged as a pivotal area in maritime traffic studies. Within this domain, the precise forecasting of ship trajectories stands as a central challenge. In this study, we propose the multi-gated attention encoder decoder (MGAED) network, a model based on an encoder–decoder structure specialized for predicting ship trajectories in canals. The model employs a long short-term memory network (LSTM) as an encoder, combined with multiple Gated Recurrent Units (GRUs) and an attention mechanism for the decoder. Long-term dependencies in time-series data are captured through GRUs, while the attention mechanism is used to strengthen the model’s ability to capture key information, and a soft threshold residual structure is introduced to handle sparse features, thus enhancing the model’s generalization ability and robustness. The efficacy of our model is substantiated by an extensive evaluation against current deep learning benchmarks. Through comprehensive comparison experiments with existing deep learning methods, our model shows significant improvements in prediction accuracy, with an at least 9.63% reduction in the mean error (MAE) and an at least 20.0% reduction in the mean square error (MSE), providing a new solution to improve the accuracy and efficiency of ship trajectory prediction. Full article

(This article belongs to the Section Ocean Engineering)

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21 pages, 8665 KiB

Open AccessViewpoint

Study on the Estimation Method of Wind Resistance Considering Self-Induced Wind by Ship Advance Speed

by Hyounggil Park, Pyungkuk Lee, Jinkyu Kim, Heejung Kim, Heedong Lee and Youngchul Lee

J. Mar. Sci. Eng. 2024, 12(10), 1694; https://doi.org/10.3390/jmse12101694 - 24 Sep 2024

Abstract

A numerical analysis of the wind load for the purpose of evaluating the wind resistance acting on a ship and the validity of the wind profile applied to determine the wind load coefficient were conducted. Through the evaluation of estimation results by a [...] Read more.

A numerical analysis of the wind load for the purpose of evaluating the wind resistance acting on a ship and the validity of the wind profile applied to determine the wind load coefficient were conducted. Through the evaluation of estimation results by a wind tunnel test, CFD analysis, and present semi-empirical formulae, it was recognized that the difference in estimation of ship resistance due to wind could not be ignored. In order to identify the main causes of the difference, extensive analyses were performed for a container, tanker, and LNG carrier. In particular, the estimation results for a container ship with two islands showed unreliable results. The main reason for the difference is that each method reflects the wind speed in the vertical direction differently, and the wind profile applied when considering the self-induced wind effect is not a uniform wind profile. In the calculation of wind resistance by self-induced wind, wind resistance estimation results differed by about 1.5% to 3.4% depending on the application of uniform or non-uniform wind profile. The total wind resistance acting on the vessel shall be divided into wind resistance from a stationary vessel without speed and wind resistance caused by the forward speed of the vessel in no wind conditions. Therefore, it is reasonable to apply a uniform wind profile to estimate wind resistance caused by the ship’s forward speed, while a wind profile that reflects the effect of changes in the ship’s vertical speed should be applied to estimate the wind resistance caused by the ship’s forward speed. Full article

(This article belongs to the Special Issue Hydrodynamics and Safety Issues in Modern Ship Design)

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19 pages, 7507 KiB

Open AccessArticle

Spatiotemporal Climatology of Georgia Tropical Cyclones and Associated Rainfall

by Reilly Corkran, Jill Trepanier and Vincent Brown

J. Mar. Sci. Eng. 2024, 12(10), 1693; https://doi.org/10.3390/jmse12101693 - 24 Sep 2024

Abstract

Tropical cyclones (TCs), often characterized by high wind speeds and heavy rainfall, cause widespread devastation, affecting millions of people and leading to economic losses worldwide. TC-specific research in Georgia is scarce, likely due to the minimal geographical extent of its coast and the [...] Read more.

Tropical cyclones (TCs), often characterized by high wind speeds and heavy rainfall, cause widespread devastation, affecting millions of people and leading to economic losses worldwide. TC-specific research in Georgia is scarce, likely due to the minimal geographical extent of its coast and the infrequency of direct landfalls. Research on Georgia TCs does not account for storms that make landfall in other southeastern states (e.g., Florida) and continue north, northeast, or northwest into Georgia. This study used the North Atlantic Basin hurricane database (HURDAT2) to quantify the spatiotemporal patterns of direct and indirect landfalling of Georgia tropical cyclones (>16 ms⁻¹) from 1851 to 2021. TC-induced rainfall was also quantified using rainfall data (nClimGrid-Daily and nClimGrid) from 1951 to 2021 to estimate the proportion of Georgia’s total annual and monthly rainfall attributed to TCs. A multi-methodological approach, incorporating statistics and mapping, is employed to assess the trends of Georgia’s tropical cyclones and the associated rainfall. The study analyzed 113 TCs and found that, on average, less than one TC annually (

\bar{x}

= 0.66) traverses the state. September averaged the highest percentage (25%) of TC-induced rainfall, followed by October (14%), and August (13%). This pattern aligns with the TC season, with the highest frequency of TCs occurring in September (n = 35), followed by August (n = 25), and October (n = 18). We found that 10% of tropical storms make landfall on the coastline, while the remaining 91% enter Georgia by making landfall in Florida (92%), Louisiana (7%), or South Carolina (1%) first. A threat of TCs during the peak of the season emphasizes the importance of heightened awareness, increased planning practices, and resource allocation during these periods to protect Georgia’s history and natural beauty, and its residents. Full article

(This article belongs to the Special Issue Coastal Disaster Assessment and Response)

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13 pages, 11800 KiB

Open AccessArticle

Numerical Simulation of Subaerial Granular Landslide Impulse Waves and Their Behaviour on a Slope Using a Coupled Smoothed Particle Hydrodynamics–Discrete Element Method

by Feidong Zheng, Qiang Liu, Jinchao Xu, Aqiang Ming and Jia Dong

J. Mar. Sci. Eng. 2024, 12(10), 1692; https://doi.org/10.3390/jmse12101692 - 24 Sep 2024

Abstract

Numerical simulations were conducted to investigate the wave features of subaerial granular landslide-generated impulse waves and their impact on slopes. A numerical solution was obtained by coupling smoothed particle hydrodynamics (SPH) and the discrete element method (DEM). Several predictive equations were tested for [...] Read more.

Numerical simulations were conducted to investigate the wave features of subaerial granular landslide-generated impulse waves and their impact on slopes. A numerical solution was obtained by coupling smoothed particle hydrodynamics (SPH) and the discrete element method (DEM). Several predictive equations were tested for their applicability in predicting the maximum crest amplitude of impulse waves generated by slides of different shapes. The results indicated that the predictive model developed by Heller and Hager, utilising slide centroid impact velocity, showed favourable prediction accuracy for the maximum crest amplitude, almost independent of the slide shape at impact. Regarding the leading wave, although the wave profile and velocity distribution deviated significantly from a solitary wave of the same wave amplitude, the maximum run-up could be satisfactorily estimated using solitary wave theory. In addition, the increase in the maximum dynamic forces exerted by the impulse waves on the slope followed a power law with the incident wave amplitude. Full article

(This article belongs to the Special Issue Hydrodynamics and Water Environment Characteristics in Coastal Areas)

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19 pages, 6333 KiB

Open AccessArticle

Notes on Towed Self-Propulsion Experiments with Simulated Managed Ice in Traditional Towing Tanks

by José Enrique Gutiérrez-Romero, Blas Zamora-Parra, Samuel Ruiz-Capel, Jerónimo Esteve-Pérez, Alejandro López-Belchí, Pablo Romero-Tello and Antonio José Lorente-López

J. Mar. Sci. Eng. 2024, 12(10), 1691; https://doi.org/10.3390/jmse12101691 - 24 Sep 2024

Abstract

Efficiency estimation of a propeller behind a vessel’s hull while sailing through ice floes, together with the ship’s resistance to motion, is a key factor in designing the power plant and determining the safety measures of a ship. This paper encloses the results [...] Read more.

Efficiency estimation of a propeller behind a vessel’s hull while sailing through ice floes, together with the ship’s resistance to motion, is a key factor in designing the power plant and determining the safety measures of a ship. This paper encloses the results from the experiments conducted at the CEHINAV towing tank, which consisted of analyzing the influence of the concentration at the free surface of artificial blocks, simulating ice, in propeller–block interactions. Thrust and torque were measured for a towed self-propelled ship model through simulated broken ice blocks made of paraffin wax. Three block concentrations of different block sizes and three model speeds were studied during the experimentation. Open-water self-propulsion tests and artificial broken ice towed self-propulsion tests are shown and compared in this work. The most relevant observations are outlined at the end of this paper, as well as some guidelines for conducting artificial ice-towed self-propulsion tests in traditional towing tanks. Full article

(This article belongs to the Special Issue Ice-Structure Interaction in Marine Engineering)

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22 pages, 19366 KiB

Open AccessArticle

Selection Results of Solid Material for Horizontal and Highly-Deviated Well Completion Gravel-Packing: Experiments, Numerical Simulation and Proposal

by Haoxian Shi, Changyin Dong, Xinjie Zhan, Chenfeng Liu, Lixia Li, Jianrong Ji, Yanjiang Yu and Zhendong Li

J. Mar. Sci. Eng. 2024, 12(10), 1690; https://doi.org/10.3390/jmse12101690 - 24 Sep 2024

Abstract

Lightweight and ultra-lightweight solid materials are being used in gravel packing for horizontal wells instead of traditional quartz and ceramsite to decrease the risk of premature plugging and improve packing efficiency. Physical and numerical simulation experiments of gravel packing were conducted to assess [...] Read more.

Lightweight and ultra-lightweight solid materials are being used in gravel packing for horizontal wells instead of traditional quartz and ceramsite to decrease the risk of premature plugging and improve packing efficiency. Physical and numerical simulation experiments of gravel packing were conducted to assess the effectiveness of reducing solid material density and investigate its impact on packing and sand control. Packed gravel destabilization experiments highlighted the importance of high-compaction degree packing for effective sand control. Further gravel packing experiments examined the packing performance of different solid materials, revealing that lightweight solids have minimal gravitational deposition effect because their density is similar to the gravel slurry, relying primarily on fluid flow for compaction. The numerical simulation indicated that lightweight ceramsite is unsuitable for horizontal and highly-deviated wells because of its poor compaction degree and sand control, especially with high-viscosity slurry. High-density particles enhance gravitational deposition, improving packing compaction and sand control. Lightweight materials are recommended only when advanced plugging of α wave packing cannot be avoided. In highly-deviated wells, high-density materials significantly improve packing stability and sand control. This study provides clear technical guidelines for selecting solid materials for gravel packing in horizontal and highly-deviated wells. Full article

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

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17 pages, 10593 KiB

Open AccessArticle

A High-Precision, Ultra-Short Baseline Positioning Method for Full Sea Depth

by Yeyao Liu, Jingfeng Xue and Wei Wang

J. Mar. Sci. Eng. 2024, 12(10), 1689; https://doi.org/10.3390/jmse12101689 - 24 Sep 2024

Abstract

To fulfill the demand for high-precision underwater acoustic positioning at full sea depth, an ultra-short baseline (USBL) positioning method with the square array based on the least squares estimating signal parameters via rotational invariance techniques (LS-ESPRIT) algorithm is presented in this paper. A [...] Read more.

To fulfill the demand for high-precision underwater acoustic positioning at full sea depth, an ultra-short baseline (USBL) positioning method with the square array based on the least squares estimating signal parameters via rotational invariance techniques (LS-ESPRIT) algorithm is presented in this paper. A combination of beam tracking and beamforming is employed to improve the accuracy of direction-of-arrival (DOA) estimation and, consequently, enhance overall positioning accuracy. In order to mitigate the issue of position jumping resulting from phase ambiguity in traditional four-element cross arrays, we have improved the stability of the positioning algorithm by utilizing a multi-element square array and employing the LS-ESPRIT algorithm for DOA estimation. Furthermore, the signal detection method integrating the correlation coefficient and ascending/descending chirp signals is employed to enhance the reliability of the location algorithm. Simulation analysis and experimental results demonstrate that the proposed algorithm effectively enhances positioning accuracy and improves the problem of jumping in positioning results. Full article

(This article belongs to the Special Issue Applications of Underwater Acoustics in Ocean Engineering)

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34 pages, 19538 KiB

Open AccessArticle

Coupled Motion Response Analysis for Dynamic Target Salvage under Wave Action

by Gang Sun, Shengtao Chen, Hongkun Zhou and Fei Wan

J. Mar. Sci. Eng. 2024, 12(9), 1688; https://doi.org/10.3390/jmse12091688 - 23 Sep 2024

Abstract

The strategic recovery of buoys is a critical task in executing deep-sea research missions, as nations extend their exploration of marine territories. This study primarily investigates the dynamics of remotely operated vehicle (ROV)-assisted salvage operations for floating bodies during the recovery of dynamic [...] Read more.

The strategic recovery of buoys is a critical task in executing deep-sea research missions, as nations extend their exploration of marine territories. This study primarily investigates the dynamics of remotely operated vehicle (ROV)-assisted salvage operations for floating bodies during the recovery of dynamic maritime targets. It focuses on the hydrodynamic coefficients of dual floating bodies in this salvage process. The interaction dynamics of the twin floats are examined using parameters such as the kinematic response amplitude operator (RAO), added mass, damping coefficient, and mean drift force. During the “berthing stage”, when the double floats are at Fr = 0.15–0.18, their roll and yaw Response Amplitude Operators are diminished, resulting in smoother motion. Thus, the optimal berthing speed range for this stage is Fr = 0.15–0.18. During the “side-by-side phase”, the spacing between the ROV and FLOAT under wave action should be approximately 0.4 L to 0.5 L. The coupled motion of twin floating bodies under the influence of following waves can further enhance their stability. The ideal towing speed during the “towing phase” is Fr = 0.2. This research aims to analyze the mutual influence between two floating bodies under wave action. By simulating the coupled motion of dual dynamic targets, we more precisely assess the risks and challenges inherent in salvage operations, thus providing a scientific basis for the design and optimization of salvage strategies. Full article

(This article belongs to the Special Issue Advances in Marine Engineering Hydrodynamics)

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2 pages, 528 KiB

Open AccessCorrection

Correction: Jung et al. Heat Integration of Liquid Hydrogen-Fueled Hybrid Electric Ship Propulsion System. J. Mar. Sci. Eng. 2023, 11, 2157

by Wongwan Jung, Jinkwang Lee and Daejun Chang

J. Mar. Sci. Eng. 2024, 12(9), 1687; https://doi.org/10.3390/jmse12091687 - 23 Sep 2024

Abstract

Error in Figure [...] Full article

22 pages, 14841 KiB

Open AccessArticle

Hydrodynamics and Sediment Transport Under Solitary Waves in the Swash Zone

by Shuo Li, Wenxin Li, Huabin Shi and Xiafei Guan

J. Mar. Sci. Eng. 2024, 12(9), 1686; https://doi.org/10.3390/jmse12091686 - 23 Sep 2024

Abstract

Swash–swash interaction is a common natural phenomenon in the nearshore region, characterized by complex fluid motion. The characteristics of swash–swash interaction are crucial to sediment transport, subsequently affecting the beach morphology. This study investigates the hydrodynamics and sediment transport in swash–swash interaction under [...] Read more.

Swash–swash interaction is a common natural phenomenon in the nearshore region, characterized by complex fluid motion. The characteristics of swash–swash interaction are crucial to sediment transport, subsequently affecting the beach morphology. This study investigates the hydrodynamics and sediment transport in swash–swash interaction under two successive solitary waves using a two-phase Smoothed Particle Hydrodynamics (SPH) model. The effects of the time interval between the two waves are examined. It is shown that the time interval has a minor effect on the breaking and swash–swash interacting patterns as well as the final beach morphology but influences the run-up of the second wave and the instantaneous sediment flux. Under wave breaking in the swash–swash interaction, there is significant sediment suspension due to strong vortices, and the suspended sediment forms a plume upward from the bed. The sediment plumes gradually settle down as the vortices decay. These insights enhance the understanding of sediment transport and beach morphology under complex swash–swash interaction. Full article

(This article belongs to the Section Coastal Engineering)

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2 pages, 129 KiB

Open AccessEditorial

Challenges and Opportunities of Maritime Transport in the Post-Epidemic Era

by Guangnian Xiao and Lang Xu

J. Mar. Sci. Eng. 2024, 12(9), 1685; https://doi.org/10.3390/jmse12091685 - 23 Sep 2024

Abstract

The global outbreak of COVID-19 has cast a protracted shadow over the international economic landscape, with maritime transport emerging as a cornerstone of resilience and adaptation [...] Full article

(This article belongs to the Special Issue Challenges and Opportunities of Maritime Transport in the Post-Epidemic Era)

18 pages, 52176 KiB

Open AccessArticle

Design and Deployment of a Floating Porous Screen Breakwater in a Mesotidal Environment

by Brandon Lieberthal, Richard Perry, Elisabeth Younce, Liam Hanley, Mary Bryant and Kimberly Huguenard

J. Mar. Sci. Eng. 2024, 12(9), 1684; https://doi.org/10.3390/jmse12091684 - 23 Sep 2024

Abstract

The performance of an intermediate-scale modular, permeable, floating breakwater comprised of an array of vertical screens is optimized and tested. A distinctive attribute of this breakwater design is its adaptive capacity to fluctuating water levels owing to its floating configuration, thereby preserving its [...] Read more.

The performance of an intermediate-scale modular, permeable, floating breakwater comprised of an array of vertical screens is optimized and tested. A distinctive attribute of this breakwater design is its adaptive capacity to fluctuating water levels owing to its floating configuration, thereby preserving its efficacy during high tide and storm tide scenarios—an advancement over conventional bottom-mounted structures. The initial validation of the concept was tested in a laboratory wave basin in regular waves, which demonstrated promising results for three porous panels. Next, the breakwater’s design parameters were optimized using a finite difference computational fluid dynamics software, (FLOW-3D version 2023R2), considering porosity, spacing, and panel count. A scaled prototype, representative of a 1:2 ratio was then deployed during the summer of 2022 along the coast of Castine, ME, within a mesotidal, semi-sheltered system characterized by tidal currents and waves. Notably, the breakwater succeeded in attenuating half of the wave energy for periods shorter than 4 s, evidenced by transmission coefficients below 0.5, making this technology suitable for locally generated waves with shorter periods. During storm events, instantaneous transmission coefficients decreased to as low as 0.25, coinciding with significant wave heights exceeding 0.8 m. Additionally, the efficacy of wave attenuation improved slightly over time as biofoulants adhered to the structure, thereby enhancing drag and mass. Full article

(This article belongs to the Section Ocean Engineering)

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34 pages, 23658 KiB

Open AccessArticle

Deep Learning-Based Nonparametric Identification and Path Planning for Autonomous Underwater Vehicles

by Bin Mei, Chenyu Li, Dongdong Liu and Jie Zhang

J. Mar. Sci. Eng. 2024, 12(9), 1683; https://doi.org/10.3390/jmse12091683 - 22 Sep 2024

Abstract

As the nonlinear and coupling characteristics of autonomous underwater vehicles (AUVs) are the challenges for motion modeling, the nonparametric identification method is proposed based on dung beetle optimization (DBO) and deep temporal convolutional networks (DTCNs). First, the improved wavelet threshold is utilized to [...] Read more.

As the nonlinear and coupling characteristics of autonomous underwater vehicles (AUVs) are the challenges for motion modeling, the nonparametric identification method is proposed based on dung beetle optimization (DBO) and deep temporal convolutional networks (DTCNs). First, the improved wavelet threshold is utilized to select the optimal threshold and wavelet basis functions, and the raw model test data are denoising. Second, the bidirectional temporal convolutional networks, the bidirectional gated recurrent unit, and the attention mechanism are used to achieve the nonlinear nonparametric model of the AUV motion. And the hyperparameters are optimized by the DBO. Finally, the lazy-search-based path planning and the line-of-sight-based path following control are used for the proposed AUV model. The simulation shows that the prediction accuracy of the DBO-DTCN is better than other artificial intelligence methods and mechanical models, and the path following of AUV is feasible. The methods proposed in this paper can provide an effective strategy for AUV modeling, searching, and rescue cruising. Full article

(This article belongs to the Section Ocean Engineering)

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25 pages, 8384 KiB

Open AccessArticle

Functional Conception of Biomimetic Artificial Reefs Using Parametric Design and Modular Construction

by Dmytro Maslov, Fabio Cruz, Marisa Pinheiro, Tiago Miranda, Isabel Brito Valente, Vasco Ferreira and Eduardo Pereira

J. Mar. Sci. Eng. 2024, 12(9), 1682; https://doi.org/10.3390/jmse12091682 - 20 Sep 2024

Abstract

Artificial reefs featuring different shapes and functions have been deployed around the world, causing impacts on marine ecosystems. However, the approaches typically used to deliver topological complexity, flexibility and expanding requirements to prospective structures during the initial design stages are not well established. [...] Read more.

Artificial reefs featuring different shapes and functions have been deployed around the world, causing impacts on marine ecosystems. However, the approaches typically used to deliver topological complexity, flexibility and expanding requirements to prospective structures during the initial design stages are not well established. The aim of this study was to highlight the advantages and provide evidence on how modularity and parametric design can holistically leverage the performance of multifunctional artificial reefs (MFARs). In particular, the goal was to develop a parametric design for MFAR and establish a direct relationship between specific design parameters and the MFAR target functions or design requirements. The idea of implementing the parametric design for generating the initial biomimetic geometry of the individual modular unit was explored. Furthermore, possible ways of manipulating the geometric parameters of the individual module and the whole assembly were proposed. The findings suggest that, by adopting the developed procedure and the examples studied, several functions may be reached within a single assembly: the promotion of marine biodiversity restoration, the support of scientific platforms with various sensors, as well as the development of recreational diving and of touristic attraction areas. Acquired knowledge suggests that the concept of a nature-like design approach was developed for artificial reefs with varying scales, complexity and functions, which widens the range of possibilities of how smart design of human-made underwater structures may contribute to benefiting the near shore ecosystems. Full article

(This article belongs to the Section Coastal Engineering)

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17 pages, 7723 KiB

Open AccessArticle

Periodic Behavior and Noise Characteristics of Cavitating Flow around Two-Dimensional Hydrofoils

by Namug Heo and Ji-Hye Kim

J. Mar. Sci. Eng. 2024, 12(9), 1681; https://doi.org/10.3390/jmse12091681 - 20 Sep 2024

Abstract

The occurrence of cavitation in marine propellers is a major source of noise in ships. Consequently, the occurrence and noise characteristics of cavitation must be better understood to control this issue. This study focuses on identifying the occurrence and noise characteristics of cavitating [...] Read more.

The occurrence of cavitation in marine propellers is a major source of noise in ships. Consequently, the occurrence and noise characteristics of cavitation must be better understood to control this issue. This study focuses on identifying the occurrence and noise characteristics of cavitating flow around two-dimensional (2D) hydrofoils. Using the commercial computational fluid dynamics software STAR-CCM+, a numerical analysis was conducted on the partial cavity flow occurring around 2D hydrofoils at specific angles of attack. In addition, the cavitation noise characteristics were analyzed by conducting a frequency analysis using the predicted pressure data obtained via a fluctuating pressure sensor positioned vertically above the hydrofoil. Consequently, the numerical results were compared with existing experimental data to validate the accuracy of the simulation. This study identifies the limitations of the Reynolds-averaged Navier–Stokes (RANS) method by closely comparing it with the large eddy simulation (LES) method for assessing noise characteristics in unsteady cavitating flow. Although RANS has limitations in qualitatively assessing periodic behavior compared to LES, it effectively predicts cavitation extent and is valuable for relative assessments in practical applications. Full article

(This article belongs to the Section Ocean Engineering)

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20 pages, 5481 KiB

Open AccessArticle

Ocean Currents Velocity Hindcast and Forecast Bias Correction Using a Deep-Learning Approach

by Ali Muhamed Ali, Hanqi Zhuang, Yu Huang, Ali K. Ibrahim, Ali Salem Altaher and Laurent M. Chérubin

J. Mar. Sci. Eng. 2024, 12(9), 1680; https://doi.org/10.3390/jmse12091680 - 20 Sep 2024

Abstract

Today’s prediction of ocean dynamics relies on numerical models. However, numerical models are often unable to accurately model and predict real ocean dynamics, leading to a lack of fulfillment of a range of services that require reliable predictions at various temporal and spatial [...] Read more.

Today’s prediction of ocean dynamics relies on numerical models. However, numerical models are often unable to accurately model and predict real ocean dynamics, leading to a lack of fulfillment of a range of services that require reliable predictions at various temporal and spatial scales. Indeed, a numerical model cannot fully resolve all the physical processes in the ocean due to various reasons, including biases in the initial field and calculation errors in the numerical solution of the model. Thus, bias-correcting methods have become crucial to improve the dynamical accuracy of numerical model predictions. In this study, we present a machine learning-based three-dimensional velocity bias correction method derived from historical observations that applies to both hindcast and forecast. Our approach is based on the modification of an existing deep learning model, called U-Net, designed specifically for image segmentation analysis in the biomedical field. U-Net was modified to create a Transform Model that retains the temporal and spatial evolution of the differences between the model and observations to produce a correction in the form of regression weights that evolves spatially and temporally with the model both forward and backward in time, beyond the observation period. Using daily ocean current observations from a 2.5-year current meter array deployment, we show that significant bias corrections can be conducted up to 50 days pre- or post-observations. Using a 3-year-long virtual array, valid bias corrections can be conducted for up to one year. Full article

(This article belongs to the Section Ocean Engineering)

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4 pages, 171 KiB

Open AccessEditorial

Advances in Offshore Aquaculture and Renewable Energy Production

by Huu Phu Nguyen and Chien Ming Wang

J. Mar. Sci. Eng. 2024, 12(9), 1679; https://doi.org/10.3390/jmse12091679 - 20 Sep 2024

Abstract

With the world population projected to reach 10 billion by 2050, the demand for food and energy is expected to increase significantly [...] Full article

(This article belongs to the Special Issue Advances in Offshore Aquaculture and Renewable Energy Production)

23 pages, 7572 KiB

Open AccessArticle

The Influence of the Atlantic Water Boundary Current on the Phytoplankton Composition and Biomass in the Northern Barents Sea and the Adjacent Nansen Basin

by Larisa Pautova, Marina Kravchishina, Vladimir Silkin, Alexey Klyuvitkin, Anna Chultsova, Svetlana Vazyulya, Dmitry Glukhovets and Vladimir Artemyev

J. Mar. Sci. Eng. 2024, 12(9), 1678; https://doi.org/10.3390/jmse12091678 - 20 Sep 2024

Abstract

The modern Arctic is characterized by a decreased ice cover and significant interannual variability. However, the reaction of the High Arctic ecosystem to such changes is still being determined. This study tested the hypothesis that the key drivers of changes in phytoplankton are [...] Read more.

The modern Arctic is characterized by a decreased ice cover and significant interannual variability. However, the reaction of the High Arctic ecosystem to such changes is still being determined. This study tested the hypothesis that the key drivers of changes in phytoplankton are the position and intensity of Atlantic water (AW) flow. The research was conducted in August 2017 in the northern part of the Barents Sea and in August 2020 in the Nansen Basin. In 2017, the Nansen Basin was ice covered; in 2020, the Nansen Basin had open water up to 83° N. A comparative analysis of phytoplankton composition, dominant species, abundance, and biomass at the boundary of the ice and open water in the marginal ice zone (MIZ) as well as in the open water was carried out. The total biomass of the phytoplankton in the photic layer of MIZ is one and a half orders of magnitude greater than in open water. In 2017, the maximum abundance and biomass of phytoplankton in the MIZ were formed by cold-water diatoms Thalassiosira spp. (T. gravida, T. rotula, T. hyalina, T. nordenskioeldii), associated with first-year ice. They were confined to the northern shelf of the Barents Sea. The large diatom Porosira glacialis grew intensively in the MIZ of the Nansen Basin under the influence of Atlantic waters. A seasonal thermocline, above which the concentrations of silicon and nitrogen were close to zero, and deep maxima of phytoplankton abundance and biomass were recorded in the open water. Atlantic species—haptophyte Phaeocystis pouchettii and large diatom Eucampia groenlandica—formed these maxima. P. pouchettii were observed in the Nansen Basin in the Atlantic water (AW) flow (2020); E. groenlandica demonstrated a high biomass (4848 mg m⁻³, 179.5 mg C m⁻³) in the Franz Victoria trench (2017). Such high biomass of this species in the northern Barents Sea shelf has not been observed before. The variability of the phytoplankton composition and biomass in the Franz Victoria trench and in the Nansen Basin is related to the intensity of the AW, which comes from the Frame Strait as the Atlantic Water Boundary Current. Full article

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

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23 pages, 10692 KiB

Open AccessArticle

Intelligent Fault Diagnosis Method for Constant Pressure Variable Pump Based on Mel-MobileViT Lightweight Network

by Yonghui Zhao, Anqi Jiang, Wanlu Jiang, Xukang Yang, Xudong Xia and Xiaoyang Gu

J. Mar. Sci. Eng. 2024, 12(9), 1677; https://doi.org/10.3390/jmse12091677 - 19 Sep 2024

Abstract

The sound signals of hydraulic pumps contain abundant key information reflecting their internal mechanical states. In environments characterized by high temperatures or high-speed rotation, or where sensor deployment is challenging, acoustic sensors offer non-contact and flexible arrangement features. Therefore, this study aims to [...] Read more.

The sound signals of hydraulic pumps contain abundant key information reflecting their internal mechanical states. In environments characterized by high temperatures or high-speed rotation, or where sensor deployment is challenging, acoustic sensors offer non-contact and flexible arrangement features. Therefore, this study aims to develop an intelligent fault diagnosis method for hydraulic pumps based on acoustic signals. Initially, the Adaptive Chirp Mode Decomposition (ACMD) method is employed to remove environmental noise from the acoustic signals, enhancing the feature signals. Subsequently, the Mel spectrum is extracted as the acoustic fingerprint features of various fault states of the hydraulic pump, and these features are used to train the MobileViT network, achieving accurate identification of the different fault modes. The results indicate that the proposed Mel-MobileViT model effectively identifies and classifies various faults in constant pressure variable pumps, outperforming other models. This study not only provides an efficient and reliable intelligent method for the fault diagnosis of critical industrial equipment such as hydraulic pumps, but also offers new perspectives on the application of deep learning in acoustic pattern analysis. Full article

(This article belongs to the Section Ocean Engineering)

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