Journal of Marine Science and Engineering

10 pages, 2190 KiB

Open AccessArticle

Tribological Properties of Nano-Scale Al₂O₃ Particles with Different Shapes as Lubricating Oil Additives

by Zichun Wang, Jingsi Wang, Jiayuan Wang, Heyuan Tian, Boshen Zhang, Konstantin Grinkevych and Jiujun Xu

J. Mar. Sci. Eng. 2024, 12(7), 1069; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071069 - 25 Jun 2024

Abstract

Enhancing lubrication across various tribological systems in the maritime industry is essential for improving safety, efficiency, and environmental sustainability. Al₂O₃ nanoparticles, employed as additives in lubricating oils, demonstrate favorable tribological properties including anti-wear and anti-friction characteristics. In this work, nano-scale [...] Read more.

Enhancing lubrication across various tribological systems in the maritime industry is essential for improving safety, efficiency, and environmental sustainability. Al₂O₃ nanoparticles, employed as additives in lubricating oils, demonstrate favorable tribological properties including anti-wear and anti-friction characteristics. In this work, nano-scale γ-Al₂O₃ particles with different shapes, i.e., nanosheet, nanorod, nanosphere, and irregular-shaped nanoparticles, were prepared and calcinated forming the same crystalline phase with nanoscale size, which dispersed well in lubricating oil. The tribological properties of Al₂O₃ nanoparticles as lubricating oil additives were examined using block-on-ring wear tests, and the effects of the particle shape and particle concentration were investigated. The results indicated that the frictional properties are largely influenced by the particle shape and the concentration of the Al₂O₃ additives, with the optimal concentration being around 0.1 wt% for each shape. The lubricating oil with nanosheet additives presented the best tribological performance, followed by those with nanorod, nanosphere, and irregular-shaped Al₂O₃ nanoparticle additives. Al₂O₃ nanosheets as the lubricating oil additives reduced the stress effect on the friction surface because of their larger bearing area and are inter-particle-sheared during sliding due to the movement of friction pairs, which can further improve the tribological properties compared to other shapes. Full article

(This article belongs to the Section Ocean Engineering)

14 pages, 680 KiB

Open AccessArticle

Movement Behavior of the Dusky Grouper Epinephelus marginatus (Lowe, 1834) in Early Life Stages

by Cássia Gongora Goçalo and Rubens M. Lopes

J. Mar. Sci. Eng. 2024, 12(7), 1068; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071068 - 25 Jun 2024

Abstract

The dusky grouper (Epinephelus marginatus) is a vulnerable predatory fish found in the Atlantic and Indian oceans, and in the Mediterranean Sea. This study investigates the movement patterns of grouper larvae (151 individuals) during their first feeding period (three to ten [...] Read more.

The dusky grouper (Epinephelus marginatus) is a vulnerable predatory fish found in the Atlantic and Indian oceans, and in the Mediterranean Sea. This study investigates the movement patterns of grouper larvae (151 individuals) during their first feeding period (three to ten days post hatching) through laboratory experiments offering rotifers (Brachionus sp.) and copepod nauplii as food. High-speed cameras and imaging techniques including bright field microscopy, matched filters, and holography captured rapid displacements (up to 25 body lengths per second), peduncle caudal beats (up to 40 beats s⁻¹), turns, and resting periods. Reynolds numbers ranged from <45 for routine swimming to 222 for burst swimming. Specific behaviors, including changes in swimming velocity and body movements, were observed from three days post hatching, when feeding begins, suggestive of an array of responses to environmental forcing, predator avoidance, food search, and feeding success. These findings provide insights into the critical movement performances of E. marginatus larvae, which help to unravel their ecological interactions and survival strategies. Understanding grouper larval swimming behavior is pivotal for devising effective cultivation strategies aimed at replenishing wild stocks and enhancing production for human consumption. Full article

(This article belongs to the Section Marine Aquaculture)

10 pages, 1012 KiB

Open AccessArticle

Interannual Variation of Summer Sea Surface Salinity in the Dotson–Getz Trough, West Antarctica

by Lu-Sha Yu, Hailun He, Hengling Leng and Xiaohui Chen

J. Mar. Sci. Eng. 2024, 12(7), 1067; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071067 - 25 Jun 2024

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Abstract

In this study, we explore the interannual variability of Sea Surface Salinity (SSS) in the Dotson–Getz Trough located in West Antarctica, focusing on the month of February. Utilizing the oceanic analysis product EN4, we first validate the EN4 SSS with data from a [...] Read more.

In this study, we explore the interannual variability of Sea Surface Salinity (SSS) in the Dotson–Getz Trough located in West Antarctica, focusing on the month of February. Utilizing the oceanic analysis product EN4, we first validate the EN4 SSS with data from a singular ship-based survey, and then delve into potential factors that may influence SSS, with a particular emphasis on surface freshwater flux, sea ice concentration (SIC), and also the surface stress curl, which will induce upwelling via Ekman transport to affect the SSS. Our findings primarily indicate a link between SSS and sea ice concentration, showcasing a negative correlation where the peak (average) coefficient is around −0.6 (−0.4), further affirming the substantial interannual variability of SSS in this region. Full article

(This article belongs to the Section Physical Oceanography)

12 pages, 2811 KiB

Open AccessArticle

Experimental Study on Cyclic Simple Shear Test of Coastal Tidal Soft Soil

by Xiuxia Yu, Honglei Sun, Junwei Liu, Hongxuan Zhao and Yu Han

J. Mar. Sci. Eng. 2024, 12(7), 1066; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071066 - 25 Jun 2024

Viewed by 69

Abstract

Based on undrained cyclic simple shear tests conducted on coastal tidal soft soil under various conditions of cyclic stress ratios and moisture contents, this study investigated the influence of these factors on the dynamic properties of the soil. The findings indicated that with [...] Read more.

Based on undrained cyclic simple shear tests conducted on coastal tidal soft soil under various conditions of cyclic stress ratios and moisture contents, this study investigated the influence of these factors on the dynamic properties of the soil. The findings indicated that with increasing moisture content and stress cycle ratio, the stress–strain hysteresis loop gradually expanded, resulting in a higher strain difference and a transition from a dense to a sparse curve pattern. Moreover, the symmetry of the hysteresis loop was lost in the later stages of shearing. With an increase in the number of cycles, the cumulative shear strain gradually increased, and the increase in the cyclic ratio of water content to stress reduced the number of cyclic shear cycles required to achieve failure, thereby accelerating the soil’s failure rate. A predictive formula was developed based on the experimental results to estimate the failure cycles as a function of the cyclic stress ratio and moisture content. Furthermore, the softening index decreased gradually with an increasing number of cycles, and a higher moisture content and cyclic stress ratio accelerated the soil’s softening process. It was observed that under the conditions of optimal moisture content, the soil exhibited a slower softening rate during the initial stage of shearing. Full article

(This article belongs to the Section Coastal Engineering)

23 pages, 2231 KiB

Open AccessArticle

Cross-Scale Modeling of Shallow Water Flows in Coastal Areas with an Improved Local Time-Stepping Method

by Guilin Liu, Tao Ji, Guoxiang Wu, Hao Tian and Pubing Yu

J. Mar. Sci. Eng. 2024, 12(7), 1065; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071065 - 25 Jun 2024

Viewed by 81

Abstract

A shallow water equations-based model with an improved local time-stepping (LTS) scheme is developed for modeling coastal hydrodynamics across multiple scales, from large areas to detailed local regions. To enhance the stability of the shallow water model for long-duration simulations and at larger [...] Read more.

A shallow water equations-based model with an improved local time-stepping (LTS) scheme is developed for modeling coastal hydrodynamics across multiple scales, from large areas to detailed local regions. To enhance the stability of the shallow water model for long-duration simulations and at larger LTS gradings, a prediction-correction method using a single-layer interface that couples coarse and fine time discretizations is adopted. The proposed scheme improves computational efficiency with an acceptable additional computational burden and ensures accurate conservation of time truncation errors in a discrete sense. The model performance is verified with respect to conservation and computational efficiency through two idealized tests: the spreading of a drop of shallow water and a tidal flat/channel system. The results of both tests demonstrate that the improved LTS scheme maintains precision as the LTS grading increases, preserves conservation properties, and significantly improves computational efficiency with a speedup ratio of up to 2.615. Furthermore, we applied the LTS scheme to simulate tides at grid scales of 40,000 m to 200 m for a portion of the Northwest Pacific. The proposed model shows promise for modeling cross-scale hydrodynamics in complex coastal and ocean engineering problems. Full article

(This article belongs to the Section Coastal Engineering)

19 pages, 1007 KiB

Open AccessArticle

Research on Torque Performance of Marine Hybrid Excitation Synchronous Motors Based on PSO Optimization of Magnetic Permeability Structure

by Qingliang Yang, Wendong Zhang and Chaohui Zhao

J. Mar. Sci. Eng. 2024, 12(7), 1064; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071064 - 25 Jun 2024

Viewed by 97

Abstract

The rotor magnetic shunt structure hybrid excitation synchronous motor (RMS-HESM) has been widely used in marine propulsion due to its advantages of low loss and high efficiency. The objective of this paper is to improve the output torque capability of the hybrid excitation [...] Read more.

The rotor magnetic shunt structure hybrid excitation synchronous motor (RMS-HESM) has been widely used in marine propulsion due to its advantages of low loss and high efficiency. The objective of this paper is to improve the output torque capability of the hybrid excitation motor with a rotor magnetic shunt structure by conducting a multi-objective optimization design for the magnetic permeability structure. The first step involved establishing a mathematical analytical model of average torque and torque ripple based on the fundamental principle of motor magnetization. Next, the parameters of the magnetic permeability structure were designed and analyzed using the finite element simulation method. The impact of the variations in the parameters of the magnetic permeability structure on motor torque and no−load back electromotive force was examined. Additionally, a sensitivity analysis was performed on the design variables of the magnetic permeability structure, leading to the determination of optimization parameters based on the obtained results. The adaptive inertia weight-based particle swarm algorithm (PSO) was employed to conduct a multi-objective optimization design analysis. A comparative analysis on the average torque, torque ripple, and no−load back electromotive force of the motor before and after optimization was performed using the Maxwell and Workbench and Optislong joint simulation tools. This enhancement significantly improves the torque performance of the marine motor while simultaneously optimizing the no−load back electromotive force. Full article

(This article belongs to the Section Ocean Engineering)

22 pages, 973 KiB

Open AccessArticle

Coastal Adaptation Pathways and Tipping Points for Typical Mediterranean Beaches under Future Scenarios

by Agustín Sánchez-Arcilla, Jr., Vicente Gracia and Agustín Sánchez-Arcilla

J. Mar. Sci. Eng. 2024, 12(7), 1063; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071063 - 25 Jun 2024

Viewed by 110

Abstract

Coastal zones experience increasing climatic and human pressures, which lead to growing risks and tipping points (TPs) under future scenarios and natural resource scarcity. To avoid crossing TPs with irreversible coastal losses, this paper proposes the development of adaptation pathways based on advanced [...] Read more.

Coastal zones experience increasing climatic and human pressures, which lead to growing risks and tipping points (TPs) under future scenarios and natural resource scarcity. To avoid crossing TPs with irreversible coastal losses, this paper proposes the development of adaptation pathways based on advanced coastal oceanography and engineering knowledge that enables a comprehensive assessment of evolving coastal risks. These pathways feature sequential interventions steered by simulations and observations as a function of available coastal resources (mainly space and sediment) and risks for infrastructure and socioeconomic assets. Such an adaptation has been developed for urban and peri-urban Mediterranean beaches, considering conventional coastal engineering together with nature-based solutions (NbS). Both types of interventions are assessed in terms of key physical variables, which serve to evaluate performance and estimate TPs. This analysis supports the new coastal protection and management plan promoted by the regional government of Catalonia and the coastal adaptation plan of the central government of Spain. The approach and results illustrate the potential of adaptation pathways for beach sustainability, enhancing the compatibility between short-/long-term coastal protection objectives under present/future climate and management scenarios. The development of adaptation pathways underpins increasing stakeholder cooperation to achieve shared decisions for coastal sustainability. Full article

(This article belongs to the Section Coastal Engineering)

17 pages, 8634 KiB

Open AccessArticle

Aerodynamic Performance and Coupling Gain Effect of Archimedes Spiral Wind Turbine Array

by Ke Song, Huiting Huan, Liuchuang Wei and Chunxia Liu

J. Mar. Sci. Eng. 2024, 12(7), 1062; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071062 - 24 Jun 2024

Viewed by 297

Abstract

The Archimedes spiral wind turbine (ASWT), as a novel type of horizontal-axis wind turbine, is well suited for remote islands. To explore the aerodynamic performance and coupling gain effect of ASWT array, a three-dimensional numerical simulation was carried out using the computational fluid [...] Read more.

The Archimedes spiral wind turbine (ASWT), as a novel type of horizontal-axis wind turbine, is well suited for remote islands. To explore the aerodynamic performance and coupling gain effect of ASWT array, a three-dimensional numerical simulation was carried out using the computational fluid dynamics (CFD) method. The influence of arrangement, relative spacing, and rotation configuration on the performance of a double-unit array and triangular array is studied. The results demonstrate that, in parallel arrangements, the double unit achieve higher performance than an isolated ASWT within a specific range of parallel spacing. However, the effect of performance improvement gradually diminishes as the parallel spacing increases. In tandem arrangements, the upstream unit performance remains largely unaffected when tandem spacing exceeds 5 D, while the downstream unit’s performance declines notably with reducing tandem spacing. The downstream unit in reverse rotation configuration accrues more energy than its counterpart operating at the co-rotation configuration. In triangular arrangements, the reverse rotation configuration can achieve better performance due to the meshing effect between the wake of the upstream ASWT and the downstream ASWT. This configuration allows the array system to maintain a higher maximum power output within a smaller spacing. The research results can provide a basis and reference for designing the layout scheme of a multi-unit ASWT power station. Full article

(This article belongs to the Topic Advances in Wind Energy Technology)

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33 pages, 4567 KiB

Open AccessArticle

El Niño–Southern Oscillation Diversity: Effect on Upwelling Center Intensity and Its Biological Response

by Gabriel Santiago Gutiérrez-Cárdenas, Enrique Morales-Acuña, Leonardo Tenorio-Fernández, Jaime Gómez-Gutiérrez, Rafael Cervantes-Duarte and Sergio Aguíñiga-García

J. Mar. Sci. Eng. 2024, 12(7), 1061; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071061 - 24 Jun 2024

Viewed by 327

Abstract

The influence of El Niño–Southern Oscillation (ENSO) on productivity at upwelling systems has been extensively studied. However, in recent decades, ENSO diversity has been documented; there are more frequent events with anomalies in the central Pacific (CP) causing ecological impacts that are different [...] Read more.

The influence of El Niño–Southern Oscillation (ENSO) on productivity at upwelling systems has been extensively studied. However, in recent decades, ENSO diversity has been documented; there are more frequent events with anomalies in the central Pacific (CP) causing ecological impacts that are different from the canonical events centered in the eastern Pacific (EP). We hypothesize that ENSO effects on upwelling intensity and its biological response are highly dependent on ENSO diversity. Wavelet coherence was computed for monthly standardized anomalies of Ekman transport and sea surface Chlorophyll-a (Chl-a) concentration from eight upwelling centers located along the west coast of the Baja California peninsula (1993–2022). Ekman transport (ET) showed a non-linear association with ENSO at interannual periodicities between 1.2 and 7 years, as well as semiannual scale variability. Coherence between ENSO and ET showed a reduction in upwelling intensity during CP ENSO events and an increased upwelling intensity after EP El Niño events with regional differences. Our results reveal an influence of northern Pacific circulation that subsequently influences ENSO events during its development and its peak. We detected an influence of SST and wind anomalies on the ENSO–Ekman transport connection associated with the northern Pacific Meridional Mode pattern. The CP shows an important role in sea surface Chl-a concentration anomalies (1998–2022). We highlight the conceptual relevance of distinguishing ENSO diversity, with influential ecological effects associated with CP ENSO events. Full article

(This article belongs to the Section Physical Oceanography)

14 pages, 12773 KiB

Open AccessArticle

Arctic-Type Seismoacoustic Waveguide: Theoretical Foundations and Experimental Results

by Alexey Sobisevich, Dmitriy Presnov and Andrey Shurup

J. Mar. Sci. Eng. 2024, 12(7), 1060; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071060 - 24 Jun 2024

Viewed by 200

Abstract

The results of theoretical analysis and practical implementation of seismoacoustic methods developed for monitoring ice-covered regions in the Arctic are presented and discussed. Special attention is paid to passive seismoacoustic tomography as a unique method of studying the deep structure of the lithosphere [...] Read more.

The results of theoretical analysis and practical implementation of seismoacoustic methods developed for monitoring ice-covered regions in the Arctic are presented and discussed. Special attention is paid to passive seismoacoustic tomography as a unique method of studying the deep structure of the lithosphere and hydrosphere without the use of powerful sources. One of the distinctive features of the considered approach is the use of receivers located on the ice surface to recover characteristics of Arctic-type seismoacoustic waveguide “lithosphere-hydrosphere-ice cover”. In passive monitoring, special attention is paid to reducing the noise signal accumulation time required to obtain seismoacoustic wave propagation times, as well as expanding the analyzed frequency bandwidth. The presented results can be used to develop technologies for seasonal and long-term monitoring of the currently observed variability of large areas of the Arctic region due to climatic changes. Full article

(This article belongs to the Special Issue Recent Research on the Measurement and Modeling of Sea Ice)

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15 pages, 9046 KiB

Open AccessArticle

Numerical Modelling of the Hydrodynamic Performance of Biodegradable Drifting Fish Aggregating Devices in Currents

by Tongzheng Zhang, Junbo Zhang, Qinglian Hou, Gangyi Yu, Ao Chen, Zhiqiang Liu and Rong Wan

J. Mar. Sci. Eng. 2024, 12(7), 1059; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071059 - 24 Jun 2024

Viewed by 203

Abstract

Fish Aggregating Devices (FADs) are essential supplementary structures used in tropical tuna purse-seine fishing. They are strategically placed to attract tuna species and enhance fishing productivity. The hydrodynamic performance of FADs has a direct effect on their structural and environmental safety in the [...] Read more.

Fish Aggregating Devices (FADs) are essential supplementary structures used in tropical tuna purse-seine fishing. They are strategically placed to attract tuna species and enhance fishing productivity. The hydrodynamic performance of FADs has a direct effect on their structural and environmental safety in the harsh marine environment. Conventional FADs are composed of materials that do not break down naturally, leading to the accumulation of waste in the ocean and potential negative effects on marine ecosystems. Therefore, this work aimed to examine the hydrodynamic performance of biodegradable drifting FADs (Bio-DFADs) in oceanic currents by numerical modelling. The Reynolds-averaged Navier–Stokes equation was used to solve the flow field and discretized based on the realizable k-ε turbulence model, employing the finite volume method. A set of Bio-DFADs was developed to assess the hydrodynamic performance under varying current velocities and attack angles, as well as different balsa wood diameters and sinker weights. The results indicated that the relative current velocity significantly affected the relative velocity of Bio-DFADs. The relative length of the raft significantly affected both the relative velocity and the relative wetted area in a pure stream. Finally, the diameter of the balsa wood affected the drift velocity, and the sinker’s relative weight affected the hydrodynamic performance of the Bio-DFADs. Full article

(This article belongs to the Special Issue Advanced Analysis of Marine Structures—Edition II)

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24 pages, 6978 KiB

Open AccessArticle

Conceptual Design and Structural Performance Analysis of an Innovative Deep-Sea Aquaculture Platform

by Yangyang Li, Xingwei Zhen, Yesen Zhu, Yi Huang, Lixin Zhang and Hongxia Li

J. Mar. Sci. Eng. 2024, 12(7), 1058; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071058 - 24 Jun 2024

Viewed by 139

Abstract

This paper proposes a conceptual design of an innovative deep-sea aquaculture platform that integrates a steel structural framework and high-density polyethylene (HDPE) floats. It aims to overcome the limitations of prevailing aquaculture equipment, including inadequate resistance to strong wind and waves, complex technologies, [...] Read more.

This paper proposes a conceptual design of an innovative deep-sea aquaculture platform that integrates a steel structural framework and high-density polyethylene (HDPE) floats. It aims to overcome the limitations of prevailing aquaculture equipment, including inadequate resistance to strong wind and waves, complex technologies, and prohibitively high costs. The design scheme and key parameters of the main platform, the netting system, and the mooring systems are presented. Based on the stochastic design wave method, the characteristic load response scenarios and design wave parameters are determined and analyzed. Strength analysis is conducted to assess the structural performance, vulnerabilities, and overall safety of the platform under various characteristic load conditions. The results indicate that the Von Mises stress levels across different sections of the platform conform to the allowable stress thresholds under various characteristic load conditions. However, the stress levels of the platform are notably higher when subjected to characteristic loads associated with vertical shear, vertical bending moments, and torsion about the horizontal axis, which requires further efforts in the design process to enhance the structural safety of the platform. The proposed design methodology and the presented research results can provide a wide range of references for the design and analysis of deep-sea fisheries aquaculture equipment. Full article

(This article belongs to the Section Ocean Engineering)

15 pages, 7934 KiB

Open AccessArticle

SIGAN: A Multi-Scale Generative Adversarial Network for Underwater Sonar Image Super-Resolution

by Chengyang Peng, Shaohua Jin, Gang Bian and Yang Cui

J. Mar. Sci. Eng. 2024, 12(7), 1057; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071057 - 24 Jun 2024

Viewed by 196

Abstract

Super-resolution (SR) is a technique that restores image details based on existing information, enhancing the resolution of images to prevent quality degradation. Despite significant achievements in deep-learning-based SR models, their application in underwater sonar scenarios is limited due to the lack of underwater [...] Read more.

Super-resolution (SR) is a technique that restores image details based on existing information, enhancing the resolution of images to prevent quality degradation. Despite significant achievements in deep-learning-based SR models, their application in underwater sonar scenarios is limited due to the lack of underwater sonar datasets and the difficulty in recovering texture details. To address these challenges, we propose a multi-scale generative adversarial network (SIGAN) for super-resolution reconstruction of underwater sonar images. The generator is built on a residual dense network (RDN), which extracts rich local features through densely connected convolutional layers. Additionally, a Convolutional Block Attention Module (CBAM) is incorporated to capture detailed texture information by focusing on different scales and channels. The discriminator employs a multi-scale discriminative structure, enhancing the detail perception of both generated and high-resolution (HR) images. Considering the increased noise in super-resolved sonar images, our loss function emphasizes the PSNR metric and incorporates the L2 loss function to improve the quality of the output images. Meanwhile, we constructed a dataset for side-scan sonar experiments (DNASI-I). We compared our method with the current state-of-the-art super-resolution image reconstruction methods on the public dataset KLSG-II and our self-built dataset DNASI-I. The experimental results show that at a scale factor of 4, the average PSNR value of our method was 3.5 higher than that of other methods, and the accuracy of target detection using the super-resolution reconstructed images can be improved to 91.4%. Through subjective qualitative comparison and objective quantitative analysis, we demonstrated the effectiveness and superiority of the proposed SIGAN in the super-resolution reconstruction of side-scan sonar images. Full article

(This article belongs to the Section Ocean Engineering)

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23 pages, 597 KiB

Open AccessArticle

Evaluation of Thermal and Mechanical Properties of Foamed Phosphogypsum-Based Cementitious Materials for Well Cementing in Hydrate Reservoirs

by Jiadi Tang, Yusheng Zhao, Wan Cheng, Tianle Liu, Guokun Yang, Mingsheng Chen, Gang Lei, Jian Xu and Yongning Huang

J. Mar. Sci. Eng. 2024, 12(7), 1056; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071056 - 23 Jun 2024

Viewed by 245

Abstract

As detrimental byproduct waste generated during the production of fertilizers, phosphogypsum can be harmlessly treated by producing phosphogypsum-based cementitious materials (PGCs) for offshore well cementing in hydrate reservoirs. To be specific, the excellent mechanical properties of PGCs significantly promote wellbore stability. And the [...] Read more.

As detrimental byproduct waste generated during the production of fertilizers, phosphogypsum can be harmlessly treated by producing phosphogypsum-based cementitious materials (PGCs) for offshore well cementing in hydrate reservoirs. To be specific, the excellent mechanical properties of PGCs significantly promote wellbore stability. And the preeminent temperature control performance of PGCs helps to control undesirable gas channeling, increasing the formation stability of natural gas hydrate (NGH) reservoirs. Notably, to further enhance temperature control performance, foaming agents are added to PGCs to increase porosity, which however reduces the compressive strength and increases the risk of wellbore instability. Therefore, the synergetic effect between temperature control performance and mechanical properties should be quantitatively evaluated to enhance the overall performance of foamed PGCs for well cementing in NGH reservoirs. But so far, most existing studies of foamed PGCs are limited to experimental work and ignore the synergetic effect. Motivated by this, we combine experimental work with theoretical work to investigate the correlations between the porosity, temperature control performance, and mechanical properties of foamed PGCs. Specifically, the thermal conductivity and compressive strength of foamed PGCs are accurately determined through experimental measurements, then theoretical models are proposed to make up for the non-repeatability of experiments. The results show that, when the porosity increases from 6% to 70%, the 7 d and 28 d compressive strengths of foamed PGCs respectively decrease from 21.3 MPa to 0.9 MPa and from 23.5 MPa to 1.0 MPa, and the thermal conductivity decreases from 0.33 W·m⁻¹·K⁻¹ to 0.12 W·m⁻¹·K⁻¹. Additionally, an overall performance index evaluation system is established, advancing the application of foamed PGCs for well cementing in NGH reservoirs and promoting the recycling of phosphogypsum. Full article

(This article belongs to the Special Issue Production Prediction in Onshore and Offshore Tight Reservoirs)

27 pages, 3139 KiB

Open AccessReview

Breakthrough Underwater Physical Environment Limitations on Optical Information Representations: An Overview and Suggestions

by Shuangquan Li, Zhichen Zhang, Qixian Zhang, Haiyang Yao, Xudong Li, Jianjun Mi and Haiyan Wang

J. Mar. Sci. Eng. 2024, 12(7), 1055; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071055 - 23 Jun 2024

Viewed by 229

Abstract

Underwater optics have seen a notable surge of interest in recent years, emerging as a critical medium for conveying information crucial to underwater resource exploration, autonomous underwater vehicle navigation, etc. The intricate dynamics of underwater optical transmission, influenced by factors such as the [...] Read more.

Underwater optics have seen a notable surge of interest in recent years, emerging as a critical medium for conveying information crucial to underwater resource exploration, autonomous underwater vehicle navigation, etc. The intricate dynamics of underwater optical transmission, influenced by factors such as the absorption by the water and scattering by multiple particles, present considerable challenges. One of the most critical issues is that the optical information representation methods fail to take into account the impact of the underwater physical environment. We conducted a comprehensive review and analysis of recent advancements in underwater optical transmission laws and models. We summarized and analyzed relevant research on the effects of underwater particles and turbulence on light and analyzed the polarization effects in various environments. Then, the roles of various types of underwater optical propagation models were analyzed. Although optical models in complex environments are still mostly based on Monte Carlo methods, many underwater optical propagation mechanisms have been revealed and can promote the impacts of optical information expression. We delved into the cutting-edge research findings across three key domains: the enhancement of underwater optical image quality, the 3D reconstruction from monocular images, and the underwater wireless optical communication, examining the pivotal role played by light transmission laws and models in these areas. Drawing upon our extensive experience in underwater optics, including underwater optical sensor development and experiments, we identified and underscored future directions in this field. We advocate for the necessity of further advancements in the comprehension of underwater optical laws and physical models, emphasizing the importance of their expanded application in underwater optical information representations. Deeper exploration into these areas is not only warranted but essential for pushing the boundaries of current underwater optical technologies and unlocking new potential for their application in underwater optical sensor developments, underwater exploration, environmental monitoring, and beyond. Full article

(This article belongs to the Special Issue Underwater Engineering and Image Processing)

20 pages, 1689 KiB

Open AccessArticle

Analysis of the Bending Height of Flexible Marine Vegetation

by Than Van Chau, Somi Jung, Minju Kim and Won-Bae Na

J. Mar. Sci. Eng. 2024, 12(7), 1054; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071054 - 23 Jun 2024

Viewed by 212

Abstract

Marine vegetation is increasingly viewed as a living shoreline that protects coastal communities and ecosystems from the damaging effects of wave energy. Many studies have explored the potential of marine vegetation in terms of reducing wave height, but more work is needed. Here, [...] Read more.

Marine vegetation is increasingly viewed as a living shoreline that protects coastal communities and ecosystems from the damaging effects of wave energy. Many studies have explored the potential of marine vegetation in terms of reducing wave height, but more work is needed. Here, we used particle image velocimetry, fluid–structure interaction simulation, and multiple regression analysis to estimate the bending behaviors of flexible marine vegetation in water flow, and we predicted the wave height reduction in the downstream vegetation meadow. We considered different vegetation types and water flow velocities, constructed a total of 64 cases, and derived a multiple regression equation that simply estimates the vegetation bending height with a tolerance of ~10%. When the bending height rather than the vegetation height was applied, wave height reduction was alleviated by 1.08–9.23%. Thus, flexible vegetation reduced wave height by up to ~10% less than rigid vegetation in our investigation range. This implies that the impact of bending behavior becomes more pronounced with a larger vegetation meadow. The relative % decrease in wave height reduction was greater for fully submerged vegetation compared to partially submerged vegetation. Full article

(This article belongs to the Section Ocean Engineering)

21 pages, 10458 KiB

Open AccessArticle

Response of Sediment Dynamics to Tropical Cyclones under Various Scenarios in the Jiangsu Coast

by Can Wang, Chengyi Zhao, Gang Yang, Chunhui Li, Jianting Zhu and Xiaofei Ma

J. Mar. Sci. Eng. 2024, 12(7), 1053; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071053 - 23 Jun 2024

Viewed by 216

Abstract

The Jiangsu Coast (JC), China, is an area susceptible to the impact of tropical cyclones (TCs). However, due to the lack of available on-site observation data, nearshore sedimentary dynamic processes under the impact of TCs have not been fully explored. This study developed [...] Read more.

The Jiangsu Coast (JC), China, is an area susceptible to the impact of tropical cyclones (TCs). However, due to the lack of available on-site observation data, nearshore sedimentary dynamic processes under the impact of TCs have not been fully explored. This study developed a 3D wave–current–sediment numerical model for the JC based on the Finite Volume Community Ocean Model (FVCOM) to investigate sediment dynamic responses to TCs under various scenarios, including different tracks, intensities of TCs and tidal conditions. The validation results demonstrated the model’s satisfactory performance. According to the simulation results, typhoons can significantly impact the hydrodynamics and sediment dynamics. During Typhoon Lekima in 2019, strong southeasterly winds substantially increased the current velocity, bottom stress, wave height, and suspended sediment concentration (SSC). Three typical landfall-type typhoons, with prevailing southeasterly winds, brought significant sediment flux from southeast to northwest along the coast, while the typhoon that moved northward in the Yellow Sea induced a relatively small sediment flux from north to south. Typhoons could also induce stripe-like erosion and deposition, which is closely related to seafloor topography, resulting in seabed thickness variations of up to ±0.3 m. Additionally, strengthening typhoon wind fields can lead to increased sediment flux and seabed morphological changes. Typhoon Winnie, particularly at spring tide, had a greater impact on sediment dynamics compared to other landfall typhoons. Numerical simulations showed that the typhoon-induced net sediment flux within the spring tidal cycle could increase by 80% to 100% compared to the neap tidal cycle, indicating the significant influence of tidal conditions on sediment transport during TC events. Full article

(This article belongs to the Section Physical Oceanography)

25 pages, 4141 KiB

Open AccessArticle

Lift–Drag Performance of a New Unmanned Aerial Vehicle in Different Media and Ground Effect

by Wenhua Wang, Lijian Wang, Kedong Zhang and Yi Huang

J. Mar. Sci. Eng. 2024, 12(7), 1052; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071052 - 22 Jun 2024

Viewed by 174

Abstract

Abstract: Water–air trans-media unmanned vehicle is a kind of aircraft, which can freely fly in the air, sail in the water and pass through free surface. For trans-media aircrafts, the development process from air–surface to air–underwater and from submarine-launched drive to autonomous [...] Read more.

Abstract: Water–air trans-media unmanned vehicle is a kind of aircraft, which can freely fly in the air, sail in the water and pass through free surface. For trans-media aircrafts, the development process from air–surface to air–underwater and from submarine-launched drive to autonomous drive is investigated. By analyzing the characteristic of manta ray, flying fish and existing aircraft, this paper proposes a new water–air trans-media unmanned vehicle with flat dish-airfoil-shaped main body and telescopic NACA-type wing. Then the numerical method to calculate the lift and drag forces is established and validated by the results of classic NACA cases. On this basis, the flow field around the new vehicle is numerically simulated, and its lift–drag performances in different media (air and water) and ground effect are analyzed, comparing it with a model inspired by the Blackwing Unmanned Aerial Vehicle (UAV). The findings illustrate the superior performance of the new vehicle in terms of lift and drag forces, offering an innovative design framework for water–air trans-media UAV applications. Full article

(This article belongs to the Section Ocean Engineering)

19 pages, 10381 KiB

Open AccessArticle

Development of an Underwater Detection Robot for the Structures with Pile Foundation

by Wenwei Zhang, Kun Zhu, Zhichun Yang, Yunling Ye, Junfeng Ding and Jin Gan

J. Mar. Sci. Eng. 2024, 12(7), 1051; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071051 - 22 Jun 2024

Viewed by 202

Abstract

Addressing the challenges for detecting underwater damage to the structures with pile foundation, this study presents the design of an adsorption-operated robotic system. Initially, a prototype is proposed for an adsorption-operated robot that is equipped with an automatic movement mechanism. To account for [...] Read more.

Addressing the challenges for detecting underwater damage to the structures with pile foundation, this study presents the design of an adsorption-operated robotic system. Initially, a prototype is proposed for an adsorption-operated robot that is equipped with an automatic movement mechanism. To account for the disturbance of the drag force in the control system, a hydrodynamic numerical model for the detection robot is established. The numerical results of the drag force are then integrated into the control system, leading to the design of a force-redeemed active disturbance rejection controller. Furthermore, a novel detection algorithm based on the image segmentation network UNet is developed for the automatic identification of damages. The performance of the controller and detection algorithm is evaluated against traditional methods. The results indicate that the proposed force-redeemed active disturbance rejection controller outperforms traditional PID and ADR controllers in terms of overshoot and adjustment time. Moreover, the developed detection algorithm exhibits superior performance in precision, F1 score, and mean intersection over union compared to the traditional algorithms of FCN, PSPnet, Deeplabv3, and UNet. Overall, this paper advances the technology of autonomous robots for underwater detection in the structures with pile foundation. Full article

(This article belongs to the Special Issue Advances in the Performance of Ships and Offshore Structures)

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24 pages, 11277 KiB

Open AccessArticle

Trawling-Induced Sedimentary Dynamics in Submarine Canyons of the Gulf of Palermo (SW Mediterranean Sea)

by Marta Arjona-Camas, Claudio Lo Iacono, Pere Puig, Tommaso Russo and Albert Palanques

J. Mar. Sci. Eng. 2024, 12(7), 1050; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071050 - 22 Jun 2024

Viewed by 460

Abstract

Bottom trawling in submarine canyons can affect their sedimentary dynamics, but studies addressing this topic are still scarce. In the Gulf of Palermo (NW Sicily, SW Mediterranean Sea), bottom trawling occurs on the continental slope, but principally concentrates within Oreto Canyon. Hydrographic profiles [...] Read more.

Bottom trawling in submarine canyons can affect their sedimentary dynamics, but studies addressing this topic are still scarce. In the Gulf of Palermo (NW Sicily, SW Mediterranean Sea), bottom trawling occurs on the continental slope, but principally concentrates within Oreto Canyon. Hydrographic profiles and time series data of temperature, turbidity, and currents obtained by a CTD probe and by moored instruments, respectively, revealed increased turbidity values and the presence of bottom and intermediate nepheloid layers coinciding with periods of bottom trawling activity. The delay between the onset of trawling activities along the Oreto canyon axis and the increase in water turbidity at the mooring location indicate that trawling resuspended particles are progressively advected down-canyon by hydrodynamic processes. Topographic waves and near-inertial currents seem to contribute to the sediment transport of resuspended particles as bottom and intermediate nepheloid layers. Results presented in this paper highlight the complex relationship between hydrodynamic processes and sediment resuspension by trawling in submarine canyons. Full article

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19 pages, 887 KiB

Open AccessArticle

Design and Implementation of an Ice-Tethered Observation System for Melt Pond Evolution with Vision and Temperature Profile Measurements

by Guangyu Zuo, Yinke Dou, Bo Yang and Baobao An

J. Mar. Sci. Eng. 2024, 12(7), 1049; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071049 - 21 Jun 2024

Viewed by 265

Abstract

Melt pond is one of the most significant and important features of Arctic sea ice in the summer and can dramatically reduce the albedo of ice, promoting more energy into the upper ocean. The observation of the seasonal evolution of melt pond can [...] Read more.

Melt pond is one of the most significant and important features of Arctic sea ice in the summer and can dramatically reduce the albedo of ice, promoting more energy into the upper ocean. The observation of the seasonal evolution of melt pond can improve our fundamental understanding of the role and sensitivity of sea ice in the context of global climate change. In this study, an ice-tethered observation system is developed for melt pond evolution with vision and temperature profile measurements. The system composition, structure of the ice-tethered buoy, freeze-resistant camera, and thermistor chain are analyzed. A sealed shell and electric heating wires are used to increase the temperature to around the camera in low-temperature environments. The ice thickness and depth of melt pond can be inverted using a specific interface recognition algorithm. A low-light image enhancement strategy is proposed to improve the quality of images under the low lighting conditions in polar regions. The proposed system was tested in the second reservoir of Fen River, Yellow River, from 15 January to 27 January 2021. An artificial freshwater pond was used as the location for thermistor chain deployment and observation. The differences in mean square error (MSE), peak signal-to-noise ratio (PSNR), and feature similarity index (FSIM) between the original and enhanced images indicate that the proposed algorithm is suitable for low-light image enhancement. The research on the ice-tethered observation system will provide a new framework and technical support for the seasonal observation for melt pond. Full article

(This article belongs to the Section Physical Oceanography)

20 pages, 9740 KiB

Open AccessArticle

EMR-YOLO: A Study of Efficient Maritime Rescue Identification Algorithms

by Jun Zhang, Yiming Hua, Luya Chen, Li Li, Xudong Shen, Wei Shi, Shuai Wu, Yunfan Fu, Chunfeng Lv and Jianping Zhu

J. Mar. Sci. Eng. 2024, 12(7), 1048; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071048 - 21 Jun 2024

Viewed by 232

Abstract

Accurate target identification of UAV (Unmanned Aerial Vehicle)-captured images is a prerequisite for maritime rescue and maritime surveillance. However, UAV-captured images pose several challenges, such as complex maritime backgrounds, tiny targets, and crowded scenes. To reduce the impact of these challenges on target [...] Read more.

Accurate target identification of UAV (Unmanned Aerial Vehicle)-captured images is a prerequisite for maritime rescue and maritime surveillance. However, UAV-captured images pose several challenges, such as complex maritime backgrounds, tiny targets, and crowded scenes. To reduce the impact of these challenges on target recognition, we propose an efficient maritime rescue network (EMR-YOLO) for recognizing images captured by UAVs. In the proposed network, the DRC2f (Dilated Reparam-based Channel-to-Pixel) module is first designed by the Dilated Reparam Block to effectively increase the receptive field, reduce the number of parameters, and improve feature extraction capability. Then, the ADOWN downsampling module is used to mitigate fine-grained information loss, thereby improving the efficiency and performance of the model. Finally, CASPPF (Coordinate Attention-based Spatial Pyramid Pooling Fast) is designed by fusing CA (Coordinate Attention) and SPPF (Spatial Pyramid Pooling Fast), which effectively enhances the feature representation and spatial information integration ability, making the model more accurate and robust when dealing with complex scenes. Experimental results on the AFO dataset show that, compared with the YOLOv8s network, the EMR-YOLO network improves the mAP (mean average precision) and mAP50 by 4.7% and 9.2%, respectively, while reducing the number of parameters and computation by 22.5% and 18.7%, respectively. Overall, the use of UAVs to capture images and deep learning for maritime target recognition for maritime rescue and surveillance improves rescue efficiency and safety. Full article

(This article belongs to the Special Issue Motion Control and Path Planning of Marine Vehicles—2nd Edition)

21 pages, 4070 KiB

Open AccessArticle

An Experimental Study on Estimating the Quantity of Fish in Cages Based on Image Sonar

by Guohao Zhu, Mingyang Li, Jiazhen Hu, Luyu Xu, Jialong Sun, Dazhang Li, Chao Dong, Xiaohua Huang and Yu Hu

J. Mar. Sci. Eng. 2024, 12(7), 1047; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071047 - 21 Jun 2024

Viewed by 217

Abstract

To address the highly demanding assessment of the quantity of fish in cages, a method for estimating the fish quantity in cages based on image sonar is proposed. In this method, forward-looking image sonar is employed for continuous detection in cages, and the [...] Read more.

To address the highly demanding assessment of the quantity of fish in cages, a method for estimating the fish quantity in cages based on image sonar is proposed. In this method, forward-looking image sonar is employed for continuous detection in cages, and the YOLO target detection model with attention mechanism as well as a BP neural network are combined to achieve a real-time automatic estimation of fish quantity in cages. A quantitative experiment was conducted in the South China Sea to render a database for training the YOLO model and neural network. The experimental results show that the average detection accuracy mAP50 of the improved YOLOv8 is 3.81% higher than that of the original algorithm. The accuracy of the neural network in fitting the fish quantity reaches 84.63%, which is 0.72% better than cubic polynomial fitting. In conclusion, the accurate assessment of the fish quantity in cages contributes to the scientific and intelligent management of aquaculture and the rational formulation of feeding and fishing plans. Full article

(This article belongs to the Special Issue New Techniques and Equipment in Large Offshore Aquaculture Platform)

21 pages, 7515 KiB

Open AccessArticle

Fully Coupled Hydrodynamic–Mooring–Motion Response Model for Semi-Submersible Tidal Stream Turbine Based on Actuation Line Method

by Guohui Wang, Jisheng Zhang, Xiangfeng Lin, Hao Chen, Fangyu Wang and Siyuan Liu

J. Mar. Sci. Eng. 2024, 12(7), 1046; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071046 - 21 Jun 2024

Viewed by 209

Abstract

The modeling of floating tidal stream energy turbine (FTSET) systems demands significant computational resources, especially when incorporating fully coupled models that integrate hydrodynamics, mooring, motion response, and their interactions. In this study, a novel hybrid numerical model for FTSET systems has been developed, [...] Read more.

The modeling of floating tidal stream energy turbine (FTSET) systems demands significant computational resources, especially when incorporating fully coupled models that integrate hydrodynamics, mooring, motion response, and their interactions. In this study, a novel hybrid numerical model for FTSET systems has been developed, utilizing the open-source software OpenFOAM. The hydrodynamic characteristics of three-bladed vertical-axis turbines are simulated in steady, three-dimensional wave–current numerical tanks using an unsteady actuator line method (UALM). The interFoam two-phase Navier–Stokes solver within OpenFOAM is utilized to manage the kinematic characteristics of the floating platform. Mooring dynamics are addressed using the mass–spring–damper model (MoorDyn), and turbine wake dynamics are resolved using a buoyancy-modified RANS turbulence model. The comprehensive model can simulate wave, flow, mooring dynamics, platform motion, and the interactions between the turbine and platform within FTSET systems. To validate the model, several scenarios are analyzed, and experiments are conducted to validate the numerical results. The model accurately predicts platform motion responses and mooring line tensions, especially under wave–current conditions, capturing the interconnected effects of platform motion during turbine rotation. Additionally, the model extends predictions of turbine–platform wake development and interaction. Full article

(This article belongs to the Section Marine Energy)

13 pages, 4139 KiB

Open AccessArticle

Hematodinium perezi (Dinophyceae: Syndiniales) in Morocco: The First Record on the African Atlantic Coast and the First Country Record of a Parasite of the Invasive Non-Native Blue Crab Callinectes sapidus

by Amal Lamkhalkhal, Imane Rahmouni, Mohamed Selfati, Aicha Hamid, Nikol Kmentová, Maarten P.M. Vanhove and Hocein Bazairi

J. Mar. Sci. Eng. 2024, 12(7), 1045; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071045 - 21 Jun 2024

Viewed by 248

Abstract

Dinoflagellates belonging to the genus Hematodinium are key parasites of marine crustaceans, primarily decapods. In this study, we document the first report of H. perezi Chatton & Poisson, 1930 on the African Atlantic coast. This is also the first parasite record in the [...] Read more.

Dinoflagellates belonging to the genus Hematodinium are key parasites of marine crustaceans, primarily decapods. In this study, we document the first report of H. perezi Chatton & Poisson, 1930 on the African Atlantic coast. This is also the first parasite record in the invasive non-native Atlantic blue crab Callinectes sapidus Rathbun, 1896 in Morocco. Specimens of C. sapidus were sampled in winter 2023 from two Ramsar sites on the Moroccan Atlantic, namely Merja Zerga and Oualidia Lagoons, and were screened to detect the presence of parasites in their hemolymph. Based on staining fresh hemolymph smears, we did not detect Hematodinium in any of the 36 investigated individuals (20 and 16 from Merja Zerga and Oualidia Lagoons, respectively), probably due to methodological artifacts. The PCR-based method was revealed to be more accurate in diagnosing the Hematodinium parasite. It showed that at Merja Zerga Lagoon, 13 individuals of C. sapidus were infected by the parasite (prevalence: 65%) in comparison to four at Oualidia Lagoon (25%). Genetic analysis, based on the ITS1 rDNA gene from Hematodinium, confirmed the sequences as being those of Hematodinium perezi. Full article

(This article belongs to the Section Marine Ecology)

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21 pages, 1941 KiB

Open AccessArticle

Evaluation and Decision-Making Optimization of Arctic Navigation Meteorological and Sea Ice Information Websites

by Tsung-Hsuan Hsieh, Qian Meng, Bing Han, Shengzheng Wang and Wei Liu

J. Mar. Sci. Eng. 2024, 12(7), 1044; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071044 - 21 Jun 2024

Viewed by 240

Abstract

The continuous improvement in the seaworthiness of Arctic shipping routes has caused an urgent international demand for meteorological and sea ice information. In view of the diversity of Arctic meteorological and sea ice information websites and the uneven service levels of the websites, [...] Read more.

The continuous improvement in the seaworthiness of Arctic shipping routes has caused an urgent international demand for meteorological and sea ice information. In view of the diversity of Arctic meteorological and sea ice information websites and the uneven service levels of the websites, and to assist Arctic navigation ships in selecting timely, stable, and reliable meteorological and sea ice information, this paper summarizes the websites providing Arctic meteorological and sea ice information. Constructing an evaluation indicator system for the service level of the Arctic meteorological and sea ice information websites from the two dimensions of data quality and browsing experience, this system integrates the cloud model, the Dempster–Shafer (D-S) evidence theory, and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method to construct a corresponding service-level evaluation and decision optimization process of Arctic meteorological and sea ice information websites. Finally, through case analysis, the feasibility of this research method is demonstrated. Full article

(This article belongs to the Section Ocean Engineering)

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17 pages, 4812 KiB

Open AccessArticle

Rediscovering the Evasive Amphipod Idunella spinifera (Dauvin and Gentil, 1983) in the Northwest Coast of the Iberian Peninsula

by Juan Moreira, Puri Veiga and Marcos Rubal

J. Mar. Sci. Eng. 2024, 12(7), 1043; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071043 - 21 Jun 2024

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Abstract

Idunella spinifera (Dauvin and Gentil, 1983) (Crustacea: Amphipoda: Liljeborgiidae) is reported for the first time after the original description that was based on one immature female. Specimens were collected in the Ría de Muros (NW Iberian Peninsula) during the course of a study [...] Read more.

Idunella spinifera (Dauvin and Gentil, 1983) (Crustacea: Amphipoda: Liljeborgiidae) is reported for the first time after the original description that was based on one immature female. Specimens were collected in the Ría de Muros (NW Iberian Peninsula) during the course of a study on macrofauna diversity in shallow sublittoral biogenic sands along a one-year period. The male and the ovigerous female are fully described, and the data on ecology and temporal variation of abundance is provided as well. Full article

(This article belongs to the Special Issue Taxonomy, Biodiversity, and Distribution of Marine Invertebrates)

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21 pages, 12567 KiB

Open AccessArticle

Research and Application of Panoramic Visual Perception-Assisted Navigation Technology for Ships

by Chiming Wang, Xiaocong Cai, Yanan Li, Runxuan Zhai, Rongjiong Wu, Shunzhi Zhu, Liangqing Guan, Zhiqiang Luo, Shengchao Zhang and Jianfeng Zhang

J. Mar. Sci. Eng. 2024, 12(7), 1042; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071042 - 21 Jun 2024

Viewed by 297

Abstract

In response to challenges such as narrow visibility for ship navigators, limited field of view from a single camera, and complex maritime environments, this study proposes panoramic visual perception-assisted navigation technology. The approach includes introducing a region-of-interest search method based on SSIM and [...] Read more.

In response to challenges such as narrow visibility for ship navigators, limited field of view from a single camera, and complex maritime environments, this study proposes panoramic visual perception-assisted navigation technology. The approach includes introducing a region-of-interest search method based on SSIM and an elliptical weighted fusion method, culminating in the development of the ship panoramic visual stitching algorithm SSIM-EW. Additionally, the YOLOv8s model is improved by increasing the size of the detection head, introducing GhostNet, and replacing the regression loss function with the WIoU loss function, and a perception model yolov8-SGW for sea target detection is proposed. The experimental results demonstrate that the SSIM-EW algorithm achieves the highest PSNR indicator of 25.736, which can effectively reduce the stitching traces and significantly improve the stitching quality of panoramic images. Compared to the baseline model, the YOLOv8-SGW model shows improvements in the P, R, and mAP50 of 1.5%, 4.3%, and 2.3%, respectively, its mAP50 is significantly higher than that of other target detection models, and the detection ability of small targets at sea has been significantly improved. Implementing these algorithms in tugboat operations at ports enhances the fields of view of navigators, allowing for the identification of targets missed by AISs and radar systems, thus ensuring operational safety and advancing the level of vessel intelligence. Full article

(This article belongs to the Special Issue Advanced Research in Sustainable and Intelligent Navigation Control Systems for Marine Vehicles)

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22 pages, 4063 KiB

Open AccessArticle

Enhancing Few-Shot Prediction of Ocean Sound Speed Profiles through Hierarchical Long Short-Term Memory Transfer Learning

by Jiajun Lu, Hao Zhang, Sijia Li, Pengfei Wu and Wei Huang

J. Mar. Sci. Eng. 2024, 12(7), 1041; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071041 - 21 Jun 2024

Viewed by 219

Abstract

The distribution of ocean sound speed profiles (SSPs) profoundly influences the design of underwater acoustic communication and positioning systems. Conventional methods for measuring sound speed by instruments entail high time costs, while sound speed inversion methods offer rapid estimation of SSPs. However, these [...] Read more.

The distribution of ocean sound speed profiles (SSPs) profoundly influences the design of underwater acoustic communication and positioning systems. Conventional methods for measuring sound speed by instruments entail high time costs, while sound speed inversion methods offer rapid estimation of SSPs. However, these methods heavily rely on sonar observational data and lack the capacity to swiftly estimate SSPs in arbitrary oceanic regions, particularly in scenarios with few-shot data. Precisely estimating non-cooperative maritime SSPs under such conditions poses a significant challenge. To explore temporal distribution patterns of sound speed and achieve precise SSP predictions with limited data, we propose a hierarchical long short-term memory transfer learning (H-LSTM-TL) framework. The core idea involves pre-training the base model on extensive public datasets, transferring the acquired knowledge to task models, and fine-tuning the task model on few-shot data to predict future SSPs. Through H-LSTM-TL, it accelerates model convergence, enhances sensitivity to few-shot input data, alleviates overfitting issues, and notably improves the accuracy of SSP predictions. Experimental results demonstrate that the H-LSTM-TL model exhibits strong generalization capabilities in few-shot data scenarios, effectively reducing overfitting problems and proving its applicability for rapid prediction of SSPs. Full article

(This article belongs to the Section Ocean Engineering)

46 pages, 11179 KiB

Open AccessReview

Innovations in Offshore Wind: Reviewing Current Status and Future Prospects with a Parametric Analysis of Helical Pile Performance for Anchoring Mooring Lines

by Ammar Alnmr and Mais Mayassah

J. Mar. Sci. Eng. 2024, 12(7), 1040; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse12071040 - 21 Jun 2024

Viewed by 199

Abstract

This study examines the current status and future potential of the offshore wind sector. Offshore wind is pivotal in transitioning to a low-carbon society and meeting rising energy demands, despite being capital-intensive. The industry aims to develop larger-scale wind farms in deeper ocean [...] Read more.

This study examines the current status and future potential of the offshore wind sector. Offshore wind is pivotal in transitioning to a low-carbon society and meeting rising energy demands, despite being capital-intensive. The industry aims to develop larger-scale wind farms in deeper ocean locations, with projections indicating significant cost reductions. To explore deeper ocean areas, specialized foundations like floating platforms moored to the seabed are required. This study proposes helical piles anchored in the seabed as a method to secure mooring lines. Using Plaxis 3D, a parametric examination was conducted on helical piles with two plates: one fixed at the pile’s toe and the other varying in position between 0.5 and 13 m from the seabed surface. Load inclination angles (0, 20, 40, and 60 degrees) were used to simulate mooring line loads. Results indicate the optimal Zh/Z ratios for maintaining load-bearing capacity and stability: 0.12 (10 mm movements), 0.22 (25 mm), and 0.26 (50 mm) for small shaft diameters; and 0.34 (10 mm), 0.38 (25 mm), and 0.46 (50 mm) for large shaft diameters. These findings highlight the importance of specific load inclination angles based on shaft diameter and allowable movement for effective performance. Full article

(This article belongs to the Special Issue Advance in Marine Geotechnical Engineering)

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J. Mar. Sci. Eng., Volume 12, Issue 7 (July 2024) – 34 articles

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