Journal Description
Journal of Marine Science and Engineering
Journal of Marine Science and Engineering
is an international, peer-reviewed, open access journal on marine science and engineering, published monthly online by MDPI. The Australia New Zealand Marine Biotechnology Society (ANZMBS) is affiliated with JMSE and their members receive discounts on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed with Scopus, SCIE (Web of Science), GeoRef, Inspec, AGRIS, and other databases.
- Journal Rank: JCR - Q1 (Engineering, Marine) / CiteScore - Q2 (Civil and Structural Engineering)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15.4 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.9 (2022);
5-Year Impact Factor:
2.9 (2022)
Latest Articles
Practical Formula for Predicting the Residual Deflection Evolution of Steel Plates Subjected to Repeated Impacts
J. Mar. Sci. Eng. 2024, 12(6), 956; https://doi.org/10.3390/jmse12060956 - 6 Jun 2024
Abstract
Offshore structures and ships can be progressively damaged due to repeated mass impacts induced by contacts with ships, ice floes, and dropped and/or floating other objects while in service. This paper aims to predict the residual deflection evolution of the marine structures under
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Offshore structures and ships can be progressively damaged due to repeated mass impacts induced by contacts with ships, ice floes, and dropped and/or floating other objects while in service. This paper aims to predict the residual deflection evolution of the marine structures under such impact repetitions. The side hull structures of the general ice-class vessels were selected for this study. The numerical simulations were performed to predict the deflection response of repeatedly impacted stiffened plates by using the software package Abaqus 6.13. For the simulations, the strain hardening of the relevant ice-class steel grade was adopted using the proposed constitutive equations, and the strain-rate hardening effects were taken into account by employing the existing formulations. The developed numerical model was substantiated against tests available in the open literature. Based on the validated model, a parametric study on various stiffened plates was performed. The evolution of the residual deflection of the repeatedly impacted plates with actual scantlings and various impact scenarios was investigated. A practical formula for the prediction of the residual deflection evolution of the plates under repeated mass impacts was proposed based on the regression analysis of the parametric study results. The reliability and accuracy of the proposed formula were confirmed through comparisons with numerical simulations and existing analytical formulations. It is expected that the proposed formula can be efficiently employed as a quick-hand tool for the reliable prediction of the residual deflection evolution incurred by repeated mass impacts.
Full article
(This article belongs to the Section Ocean Engineering)
Open AccessArticle
Application of a Statistical Regression Technique for Dynamic Analysis of Submarine Pipelines
by
Begum Yurdanur Dagli
J. Mar. Sci. Eng. 2024, 12(6), 955; https://doi.org/10.3390/jmse12060955 - 6 Jun 2024
Abstract
This study employs a statistical regression technique to investigate the maximum displacement, stress, and natural vibration frequencies of a submarine pipeline subjected to hydrodynamic wave forces. Eighteen pipeline models are designed, varying in wall thickness from 10 mm to 30 mm and diameter
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This study employs a statistical regression technique to investigate the maximum displacement, stress, and natural vibration frequencies of a submarine pipeline subjected to hydrodynamic wave forces. Eighteen pipeline models are designed, varying in wall thickness from 10 mm to 30 mm and diameter from 500 mm to 1000 mm. The hydrodynamic drag and inertia forces are performed by using the Morison equation. Computer-aided Finite Element Analysis is employed to simulate the complex interactions between the fluid and structure in 18 pipelines. Multiple Regression technique is used to evaluate the reliability metrics, considering uncertainties in geometrical properties affecting pipeline performance. Full Quadratic models are developed for expressing more effective and concise mathematical equations. Analysis of Variance (ANOVA) is performed to determine the adequacy of the model in representing the observed data. The Coefficient of Determination (R2), Mean Square Error (MSE), and Mean Absolute Error (MAE) are calculated to assess the equation’s predictive accuracy and reliability. The results confirm the suitability of the suggested regression technique for analyzing the relationships between predictor variables and the response variable.
Full article
(This article belongs to the Section Coastal Engineering)
Open AccessArticle
A Joint Graph-Based Approach for Simultaneous Underwater Localization and Mapping for AUV Navigation Fusing Bathymetric and Magnetic-Beacon-Observation Data
by
Shuai Chang, Dalong Zhang, Linfeng Zhang, Guoji Zou, Chengcheng Wan, Wencong Ma and Qingji Zhou
J. Mar. Sci. Eng. 2024, 12(6), 954; https://doi.org/10.3390/jmse12060954 - 6 Jun 2024
Abstract
Accurate positioning is the necessary basis for autonomous underwater vehicles (AUV) to perform safe navigation in underwater tasks, such as port environment monitoring, target search, and seabed exploration. The position estimates of underwater navigation systems usually suffer from an error accumulation problem, which
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Accurate positioning is the necessary basis for autonomous underwater vehicles (AUV) to perform safe navigation in underwater tasks, such as port environment monitoring, target search, and seabed exploration. The position estimates of underwater navigation systems usually suffer from an error accumulation problem, which makes the AUVs difficult use to perform long-term and accurate underwater tasks. Underwater simultaneous localization and mapping (SLAM) approaches based on multibeam-bathymetric data have attracted much attention for being able to obtain error-bounded position estimates. Two problems limit the use of multibeam bathymetric SLAM in many scenarios. The first is that the loop closures only occur in the AUV path intersection areas. The second is that the data association is prone to failure in areas with gentle topographic changes. To overcome these problems, a joint graph-based underwater SLAM approach that fuses bathymetric and magnetic-beacon measurements is proposed in this paper. In the front-end, a robust dual-stage bathymetric data-association method is used to first detect loop closures on the multibeam bathymetric data. Then, a magnetic-beacon-detection method using Euler-deconvolution and optimization algorithms is designed to localize the magnetic beacons using a magnetic measurement sequence on the path. The loop closures obtained from both bathymetric and magnetic-beacon observations are fused to build a joint-factor graph. In the back-end, a diagnosis method is introduced to identify the potential false factors in the graph, thus improving the robustness of the joint SLAM system to outliers in the measurement data. Experiments based on field bathymetric datasets are performed to test the performance of the proposed approach. Compared with classic bathymetric SLAM algorithms, the proposed algorithm can improve the data-association accuracy by 50%, and the average positioning error after optimization converges to less than 10 m.
Full article
(This article belongs to the Special Issue Future Maritime Transport: Trends and Solutions)
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Open AccessArticle
A Laboratory Dataset on Transport and Deposition of Spherical and Cylindrical Large Microplastics for Validation of Numerical Models
by
Mostafa Bigdeli, Abdolmajid Mohammadian and Abolghasem Pilechi
J. Mar. Sci. Eng. 2024, 12(6), 953; https://doi.org/10.3390/jmse12060953 - 6 Jun 2024
Abstract
The widespread presence of micro-sized plastic pollution has raised concerns due to their unique physical and toxic properties. Each year, water bodies carry millions of tons of plastic into the ocean. The inherent characteristics (such as size, shape, and density) of microplastics (MPs),
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The widespread presence of micro-sized plastic pollution has raised concerns due to their unique physical and toxic properties. Each year, water bodies carry millions of tons of plastic into the ocean. The inherent characteristics (such as size, shape, and density) of microplastics (MPs), along with flow factors like speed, depth, and pressure, significantly influence how MPs are transported and deposited. Therefore, this research aimed to gather experimental data on the transport and deposition of MPs to serve as a benchmark for numerical modeling. To achieve this goal, various test scenarios were set up in a straight channel flume to investigate different flow velocities, channel dimensions, and particle shapes. It was observed that cylindrical particles with the same density and similar size were more likely to become trapped compared to spherical particles. This study represents progress towards validating numerical models concerning the transport and deposition of microplastics.
Full article
(This article belongs to the Section Marine Environmental Science)
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Open AccessArticle
Study of Effects on Performances and Emissions of a Large Marine Diesel Engine Partially Fuelled with Biodiesel B20 and Methanol
by
Nicolae Adrian Visan, Dan Catalin Niculescu, Radu Ionescu, Ernst Dahlin, Magnus Eriksson and Radu Chiriac
J. Mar. Sci. Eng. 2024, 12(6), 952; https://doi.org/10.3390/jmse12060952 - 5 Jun 2024
Abstract
The impact of fossil fuel utilisation in different combustion systems on climate change due to greenhouse gas accumulation in the atmosphere is rather evident. A part of these gases comes from the large engines used for propulsion in marine applications. In the continuous
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The impact of fossil fuel utilisation in different combustion systems on climate change due to greenhouse gas accumulation in the atmosphere is rather evident. A part of these gases comes from the large engines used for propulsion in marine applications. In the continuous global effort made by engine manufacturers to mitigate this negative impact, one way is represented by the utilisation of alternative fuels such as biodiesel and methanol, based on dedicated research to fulfil the more stringent regulations concerning pollutant emissions issued by piston heat engines. In this study, a numerical investigation was conducted on a four-stroke large marine diesel engine (ALCO 16V 251C) at several engine speeds and full load conditions. Different blends of diesel–methanol and biodiesel B20–methanol with methanol mass fractions of 10% and 20% were considered for theoretical analysis in two techniques of methanol supply: direct injection mode of a blend of base fuel diesel/biodiesel B20 with methanol and injection of methanol after the intercooler, and direct injection of the base fuel. The results show that, if 10% in power loss can be acceptable, then for diesel–methanol 10%, in the direct injection technology, the NOx emission can be reduced up to 19%, but with a compromise of an 8% increase in SOOT emission, while for biodiesel B20–methanol 10%, with the same direct injection method, the NOx emissions increase by up to 58% with the benefit of reducing SOOT by up to 23% relative to the original diesel fuel operation. For a 20% methanol fraction in blend fuel, the drop in power is more than 10% regardless of the method of methanol supply and the base fuel, diesel, or B20 used.
Full article
(This article belongs to the Special Issue Advanced Technologies for New (Clean) Energy Ships)
Open AccessArticle
Liner Schedule Design under Port Congestion: A Container Handling Efficiency Selection Mechanism
by
Haibin Qu, Xudong Wang, Lingpeng Meng and Chuanfeng Han
J. Mar. Sci. Eng. 2024, 12(6), 951; https://doi.org/10.3390/jmse12060951 - 5 Jun 2024
Abstract
Port congestion significantly impacts the reliability of container ship schedules. However, the existing research often treats vessel time in port as a random variable, failing to systematically consider the complex impact of port congestion on ship schedules. This study addresses the issue of
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Port congestion significantly impacts the reliability of container ship schedules. However, the existing research often treats vessel time in port as a random variable, failing to systematically consider the complex impact of port congestion on ship schedules. This study addresses the issue of container ship schedule design under port congestion. Vessel waiting times in ports are predicted and quantified by queueing theory, along with information on vessel schedules, cargo handling volumes, and available port operating time windows. We propose a mechanism for selecting container handling efficiencies for arriving vessels, thereby determining their in-port handling times. By jointly considering the uncertainty of vessel waiting and handling times in port, we establish a mixed-integer nonlinear programming model aimed at minimizing the total cost of liner transportation services. We linearize the model and solve it using CPLEX, ultimately devising a robust ship schedule. A simulation analysis is conducted on a real liner shipping route from Asia to the Mediterranean, revealing that extreme weather events, geopolitical conflicts, and other factors can lead to severe congestion at certain ports, necessitating timely adjustments to vessel schedules by shipping companies. Moreover, such events can impact the marine fuel market, prompting shipping companies to adopt strategies such as increasing vessel numbers and reducing vessel speeds in response to high fuel prices. Additionally, the container handling efficiency selection mechanism based on information sharing enables shipping companies to flexibly design liner schedules, balancing the economic costs and service reliability of container liner transportation.
Full article
(This article belongs to the Special Issue Smart Seaport and Maritime Transport Management)
Open AccessArticle
Research on Two-Phase Flow and Wear of Inlet Pipe Induced by Fluid Prewhirl in a Centrifugal Pump
by
Jilong Chen, Xing Chen, Wenjin Li, Yuhai Zheng and Yi Li
J. Mar. Sci. Eng. 2024, 12(6), 950; https://doi.org/10.3390/jmse12060950 - 5 Jun 2024
Abstract
In deep-sea mining hydraulic lifting systems, centrifugal pumps are very important as power units. In the process of transportation, the fluid prewhirl phenomenon in the impeller inlet will lead to changes in the state of motion of the particles and fluid and cause
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In deep-sea mining hydraulic lifting systems, centrifugal pumps are very important as power units. In the process of transportation, the fluid prewhirl phenomenon in the impeller inlet will lead to changes in the state of motion of the particles and fluid and cause the wear of the inlet pipe, which can lead to centrifugal pump failure in serious cases. In this paper, a numerical simulation of the centrifugal pump is carried out based on the CFD-DEM coupling method to analyze the influence of the prewhirl on the wear of the inlet pipe. The results show that the velocity streamline near the impeller inlet position changes significantly. The flow field velocity increases along the radial direction of the inlet pipe, and it has a maximum value at r/R = 0.98. The prewhirl flow pulls the particles to change their original motion direction, and the area where the particles are subjected to high fluid force is concentrated between 0.5 d/D and 1 d/D, about 0.015 to 0.018 N, resulting in the uneven distribution of particles. The high-wear area appears in the bottom-left area (specifically, L4, L9, and L13), and this is also the location of the largest cumulative force; the high-wear area shows a triangle. The collision energy loss of particles increases due to the influence of the prewhirl, which leads to an increase in wear.
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(This article belongs to the Section Ocean Engineering)
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Open AccessArticle
Method for Delineating the Formula Limit of the Continental Shelf under the Maximum Area Principle Constraint
by
Tian Xie, Jian Dong, Lulu Tang, Mengkai Ma and Dong Wang
J. Mar. Sci. Eng. 2024, 12(6), 949; https://doi.org/10.3390/jmse12060949 - 5 Jun 2024
Abstract
In current practices of determining continental shelf area, the measured sediment thickness data do not effectively reflect the distribution of sediments across the area due to its dispersed nature. This issue raises potential limitations in unknown optimal survey line layout strategies for maximizing
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In current practices of determining continental shelf area, the measured sediment thickness data do not effectively reflect the distribution of sediments across the area due to its dispersed nature. This issue raises potential limitations in unknown optimal survey line layout strategies for maximizing the posterior determination area. This paper adopts the binary search algorithm, relies on existing sediment thickness grid data, and uses geodetic formulas to build an ellipsoidal surface grid distance calculation model. This model quickly screens potential areas for the 1% sediment thickness line candidate points set. By constraining the azimuth parameter values during the construction process of the ellipsoidal point feature buffer zones, efficiently select the candidate points set for the 1% sediment thickness line. Furthermore, by elucidating the essential meanings of points on the formula limit and combining the candidate points set of the foot of the continental slope (FOS)+60 n mile line, the polygon minimal convex hull construction technique and a baseline points optimization algorithm with a length threshold are used to efficiently select points on formula limit. Experimental results demonstrate that this method can effectively assist coastal states in optimizing the determination of continental shelf area to the fullest extent under the length threshold requirements of the United Nations Convention on the Law of the Sea. Experiments have proven that compared to the traditional intersection method, the method presented in this paper can help coastal countries delineate a larger continental shelf area. In typical application scenarios, the gain in area can reach 77,278,427 m2 accounting for 0.51% of the total area.
Full article
(This article belongs to the Section Geological Oceanography)
Open AccessArticle
Chaotic Phase Modulation Direct-Sequence Spread Spectrum-Assisted Adaptive Serial Cancellation List Decoding Method for Underwater Acoustic Communication
by
Yuan Sun, Danyang Hong, Dong Liu and Jinyu Lei
J. Mar. Sci. Eng. 2024, 12(6), 948; https://doi.org/10.3390/jmse12060948 - 5 Jun 2024
Abstract
Addressing the challenges of high decoding latency, reduced spectral efficiency, and substantial storage requirements in a Cyclic Redundancy Check (CRC)Aided Successive Cancellation List (CA-SCL) polar decoder, this paper proposes a chaotic phase modulation direct-sequence spread spectrum (CPMDSSS)-assisted adaptive serial cancellation list decoding method
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Addressing the challenges of high decoding latency, reduced spectral efficiency, and substantial storage requirements in a Cyclic Redundancy Check (CRC)Aided Successive Cancellation List (CA-SCL) polar decoder, this paper proposes a chaotic phase modulation direct-sequence spread spectrum (CPMDSSS)-assisted adaptive serial cancellation list decoding method for underwater acoustic communication. The method involves segmenting the information bits to be transmitted, computing CRC for each segment, and mapping all CRCs to a CPMDSSS, which is then modulated onto the pilot subcarriers of underwater acoustic orthogonal frequency-division multiplexing (OFDM) to increase spectral efficiency. At the receiving end, CRCs are obtained by demodulating the CPMDSSS to verify the segmented information and adaptively select the number of decoding paths. The theoretical analysis and simulation results demonstrate that compared to CA-SCL, the proposed method effectively reduces the required storage units and improves spectral efficiency, with an average reduction of approximately 80% in the decoding paths. Sea trials further indicate that the proposed method reduces the average decoding paths by approximately 71% and decreases the average decoding delay by approximately 64% compared to CA-SCL.
Full article
(This article belongs to the Special Issue Underwater Acoustic Communication and Network, 2nd Edition)
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Analysis of Carbon Emission Reduction Paths for Ships in the Yangtze River: The Perspective of Alternative Fuels
by
Chunhui Zhou, Wuao Tang, Yiran Ding, Hongxun Huang and Honglei Xu
J. Mar. Sci. Eng. 2024, 12(6), 947; https://doi.org/10.3390/jmse12060947 - 5 Jun 2024
Abstract
In recent years, carbon emission reduction in the shipping sector has increasingly garnered scholarly attention. This study delves into the pathways for carbon emission reduction in shipping across the Yangtze River, emphasizing fuel alternatives. It initiates by introducing a novel ship carbon emission
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In recent years, carbon emission reduction in the shipping sector has increasingly garnered scholarly attention. This study delves into the pathways for carbon emission reduction in shipping across the Yangtze River, emphasizing fuel alternatives. It initiates by introducing a novel ship carbon emission calculation methodology predicated on voyage data, followed by the development of a predictive model for ship carbon emissions tailored to specific voyages. Then, emission reduction scenarios for various voyage categories are designed and exemplary alternative fuels selected to assess their potential for emission mitigation. Subsequently, scenario analysis is employed to scrutinize the CO2 emission trajectories under diverse conditions, pinpointing the most efficacious route for carbon emission abatement for inland vessels. Finally, the proposed method is applied to the middle and lower reaches of the Yangtze River. The results indicate that accelerating the adoption of alternative fuels for long-distance cargo ships would greatly accelerate the development of environmentally friendly shipping. Under a scenario prioritizing zero-carbon growth, emissions from inland vessels are anticipated to reach their zenith by 2040. These findings can provide theoretical guidance for emission reductions in inland shipping and effectively promote the green and sustainable development of the shipping sector.
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(This article belongs to the Special Issue Safe Maneuvering, Efficient Navigation and Intelligent Management for Ships)
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Non-Equilibrium Scour Evolution around an Emerged Structure Exposed to a Transient Wave
by
Deniz Velioglu Sogut, Erdinc Sogut, Ali Farhadzadeh and Tian-Jian Hsu
J. Mar. Sci. Eng. 2024, 12(6), 946; https://doi.org/10.3390/jmse12060946 - 5 Jun 2024
Abstract
The present study evaluates the performance of two numerical approaches in estimating non-equilibrium scour patterns around a non-slender square structure subjected to a transient wave, by comparing numerical findings with experimental data. This study also investigates the impact of the structure’s positioning on
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The present study evaluates the performance of two numerical approaches in estimating non-equilibrium scour patterns around a non-slender square structure subjected to a transient wave, by comparing numerical findings with experimental data. This study also investigates the impact of the structure’s positioning on bed evolution, analyzing configurations where the structure is either attached to the sidewall or positioned at the centerline of the wave flume. The first numerical method treats sediment particles as a distinct continuum phase, directly solving the continuity and momentum equations for both sediment and fluid phases. The second method estimates sediment transport using the quadratic law of bottom shear stress, yielding robust predictions of bed evolution through meticulous calibration and validation. The findings reveal that both methods underestimate vortex-induced near-bed vertical velocities. Deposits formed along vortex trajectories are overestimated by the first method, while the second method satisfactorily predicts the bed evolution beneath these paths. Scour holes caused by wave impingement tend to backfill as the flow intensity diminishes. The second method cannot sufficiently capture this backfilling, whereas the first method adequately reflects the phenomenon. Overall, this study highlights significant variations in the predictive capabilities of both methods in regard to the evolution of non-equilibrium scour at low Keulegan–Carpenter numbers.
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(This article belongs to the Special Issue Coastal Disaster Assessment and Response)
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The Influence of Beachrock Outcrop on Spatial Variability in Beach Morphology
by
Junhui Xu, Yanhong Wang and Peidong Lu
J. Mar. Sci. Eng. 2024, 12(6), 945; https://doi.org/10.3390/jmse12060945 - 5 Jun 2024
Abstract
Beachrock is a type of coastal carbonate sedimentary rock developed in the sandy beach intertidal zone, widely distributed along the beach front, and the loss of beach sediment is the main cause of beachrock exposure. Based on the analysis of measured data of
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Beachrock is a type of coastal carbonate sedimentary rock developed in the sandy beach intertidal zone, widely distributed along the beach front, and the loss of beach sediment is the main cause of beachrock exposure. Based on the analysis of measured data of different exposure forms of beachrocks in profiles, this paper analyzes the main features and influences of non-dynamic factors, such as the exposure position and morphology, of beachrocks on the dynamic geomorphic processes of beaches. Studies have shown that (1) changes between beach energy dissipation bodies are significant features of coastal geomorphic processes under the influence of beachrocks. The first spatial mode of EOF analysis shows that the erosion position of beach-rock-exposed profiles is mainly concentrated in the protected and real sections of beachrock, and the first temporal mode indicates that the exposure of beachrock results in a lagged response of its profile to dynamic environmental changes. (2) The differences in the exposure forms of beachrocks determine the sand-holding space of the beach, and the differences in the lateral exposure positions of beachrocks determine the main areas where erosion occurs on the profile. Meanwhile, the geomorphic processes of their profiles show different degrees of feedback, and such geomorphic phenomena can serve as reference indicators for the stage-wise evolution process influenced by beachrocks.
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(This article belongs to the Section Coastal Engineering)
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Wave Shape Evolution from a Phase-Averaged Spectral Model
by
Floris de Wit, Marion Tissier and Ad Reniers
J. Mar. Sci. Eng. 2024, 12(6), 944; https://doi.org/10.3390/jmse12060944 - 5 Jun 2024
Abstract
In spectral wave models, the nonlinear triad source term accounts for the transfer of energy to the bound higher harmonics. This paper presents an extension to commonly used spectral models that resolves the evolution of the bound wave energy by keeping track of
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In spectral wave models, the nonlinear triad source term accounts for the transfer of energy to the bound higher harmonics. This paper presents an extension to commonly used spectral models that resolves the evolution of the bound wave energy by keeping track of the energy that has been bound by the triad interactions. This extension is referred to as the bound wave evolution (BWE) model. From this, the spatial evolution of the bound wave height is obtained, which serves as a proxy for the nonlinear wave shape. The accuracy of these bound wave heights, and thus wave shape predictions, is highly dependent on the accuracy of the triad source term. Therefore, in this study, the capability of the LTA and SPB triad formulations to capture the growth of the bound wave height is evaluated. For both of these formulations, it is found that slope dependent calibration parameters are required. Overall, despite being computationally more expensive, the SPB method proves to be significantly more accurate in predicting the bound wave evolution. In the shoaling zone, where the bound wave energy is dominated by triads, the BWE model is well capable of predicting the nonlinear wave’s shape. In the surf zone, however, where a combination of triads and wave breaking control the spectral evolution, the BWE model over-predicts the bound wave height. Nevertheless, this paper shows the promising capabilities of spectral models to predict the nonlinear wave shape.
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(This article belongs to the Section Coastal Engineering)
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Predictive Modeling of Future Full-Ocean Depth SSPs Utilizing Hierarchical Long Short-Term Memory Neural Networks
by
Jiajun Lu, Hao Zhang, Pengfei Wu, Sijia Li and Wei Huang
J. Mar. Sci. Eng. 2024, 12(6), 943; https://doi.org/10.3390/jmse12060943 - 4 Jun 2024
Abstract
The spatial-temporal distribution of underwater sound speed plays a critical role in determining the propagation mode of underwater acoustic signals. Therefore, rapid estimation and prediction of sound speed distribution are imperative for facilitating underwater positioning, navigation, and timing (PNT) services. While sound speed
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The spatial-temporal distribution of underwater sound speed plays a critical role in determining the propagation mode of underwater acoustic signals. Therefore, rapid estimation and prediction of sound speed distribution are imperative for facilitating underwater positioning, navigation, and timing (PNT) services. While sound speed profile (SSP) inversion methods offer quicker response times compared to direct measurement methods, these methods often focus on constructing spatial sound velocity fields and heavily rely on sonar observation data, thus imposing stringent requirements on data sources. To delve into the temporal distribution pattern of sound speed and achieve SSP prediction without relying on sonar observation data, we introduce the hierarchical long short-term memory (H-LSTM) neural network for SSP prediction. Our method enables the estimation of sound speed distribution without the need for on-site data measurement, significantly enhancing time efficiency. Compared to other state-of-the-art approaches, the H-LSTM model achieves a root mean square error (RMSE) of less than 1 m/s in predicting monthly average sound speed distribution. Its prediction accuracy has improved several-fold over alternative methods, which validates the robust capability of our proposed model in predicting SSP.
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(This article belongs to the Section Ocean Engineering)
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Lipid Characterization of Beach-Cast Seaweeds from Gran Canaria Island: Potential Use in Human and Animal Nutrition
by
Ana Galindo, Coraima del Mar García, José Antonio Pérez, Beatriz Abdul-Jalbar, Marianna Venuleo, Nieves Guadalupe Acosta, Manuel Marrero and Covadonga Rodríguez
J. Mar. Sci. Eng. 2024, 12(6), 942; https://doi.org/10.3390/jmse12060942 - 4 Jun 2024
Abstract
Macroalgal wracks can be considered unpleasant for beach users and, consequently, they are usually collected from most touristic beaches and discarded. However, seaweeds are an important source of bioactive lipid compounds, such as phospholipids, glycolipids, and n-3 polyunsaturated fatty acids (n-3 PUFA), displaying
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Macroalgal wracks can be considered unpleasant for beach users and, consequently, they are usually collected from most touristic beaches and discarded. However, seaweeds are an important source of bioactive lipid compounds, such as phospholipids, glycolipids, and n-3 polyunsaturated fatty acids (n-3 PUFA), displaying multiple health-promoting properties, including antioxidant and antimicrobial activities. The aim of this study is to characterize the lipid composition of twelve marine seaweed species (two green, six red, and four brown species) from macroalgal wracks of Gran Canaria Island, and to evaluate their potential use for several purposes, including human and animal nutrition. Lipid content, lipid classes, and fatty acid profiles of isolated specimens from the macroalgal wracks were determined. Lipid contents ranged between 0.27 and 3.17% of dry weight, with all species showing high phytosterols proportions and balanced omega-6/omega-3 (n-6/n-3) ratios. In addition, Cymopolia barbata, Asparagopsis sp., and Hypnea spinella seem to be an attractive source of both mono- and di-galactosyl-diacylglycerols, while A. stellata, Jania sp., and Lobophora sp. are relatively rich in n-3 LC−PUFA. Finally, both green algae showed the most favorable values for the nutritional indicators of cardiovascular health promotion. Overall, the macroalgal species analyzed could be considered as interesting sources for human and animal nutrition.
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(This article belongs to the Special Issue Algal Biotechnology: Unleashing the Potential of Algae for a Sustainable Tomorrow)
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Open AccessArticle
Analysing Spatiotemporal Variability of Chlorophyll-a Concentration and Water Surface Temperature in Coastal Lagoons of the Ebro Delta (NW Mediterranean Sea, Spain)
by
Lara Talavera, José Antonio Domínguez-Gómez, Nuria Navarro and Inmaculada Rodríguez-Santalla
J. Mar. Sci. Eng. 2024, 12(6), 941; https://doi.org/10.3390/jmse12060941 - 3 Jun 2024
Abstract
Coastal lagoons are highly productive transitional water bodies threatened by human factors and vulnerable to global climate change effects. Monitoring biophysical parameters in these ecosystems is crucial for their preservation. In this work, we used Sentinel-2 and Landsat imagery combined with in situ
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Coastal lagoons are highly productive transitional water bodies threatened by human factors and vulnerable to global climate change effects. Monitoring biophysical parameters in these ecosystems is crucial for their preservation. In this work, we used Sentinel-2 and Landsat imagery combined with in situ data to (1) develop preliminary algorithms for retrieving the Chl-a concentration and water surface temperature of six lagoons located in the Ebro Delta (NE Mediterranean Sea, Spain), and to (2) compute maps and trend lines for analysing their spatiotemporal evolution from 2015 to 2022. Our findings showed that the algorithms’ accuracy ranged from 72% to 78% and had limited potential under high Chl-a concentration regimes. Even so, they revealed the lagoons’ trophic status, usual fluctuations, and deviations of both parameters attributed to seasonal (i.e., light and temperature) and short-term physical (i.e., winds) forcing, as well as valuable spatial patterns potentially useful for conservation efforts and land use planning. Future work will focus on the acquisition of a larger in situ data sample under a range of environmental conditions to improve the algorithms’ robustness, which in turn will allow the investigation of natural and human factors controlling the dynamics of the two investigated parameters.
Full article
(This article belongs to the Special Issue Wetland Evolution Based on Remote Sensing Data)
Open AccessArticle
Reinforcement-Learning-Based Visual Servoing of Underwater Vehicle Dual-Manipulator System
by
Yingxiang Wang and Jian Gao
J. Mar. Sci. Eng. 2024, 12(6), 940; https://doi.org/10.3390/jmse12060940 - 3 Jun 2024
Abstract
As a substitute for human arms, underwater vehicle dual-manipulator systems (UVDMSs) have attracted the interest of global researchers. Visual servoing is an important tool for the positioning and tracking control of UVDMSs. In this paper, a reinforcement-learning-based adaptive control strategy for the UVDMS
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As a substitute for human arms, underwater vehicle dual-manipulator systems (UVDMSs) have attracted the interest of global researchers. Visual servoing is an important tool for the positioning and tracking control of UVDMSs. In this paper, a reinforcement-learning-based adaptive control strategy for the UVDMS visual servo, considering the model uncertainties, is proposed. Initially, the kinematic control is designed by developing a hybrid visual servo approach using the information from multi-cameras. The command velocity of the whole system is produced through a task priority method. Then, the reinforcement-learning-based velocity tracking control is developed with a dynamic inversion approach. The hybrid visual servoing uses sensors equipped with UVDMSs while requiring fewer image features. Model uncertainties of the coupled nonlinear system are compensated by the actor–critic neural network for better control performances. Moreover, the stability analysis using the Lyapunov theory proves that the system error is ultimately uniformly bounded (UUB). At last, the simulation shows that the proposed control strategy performs well in the task of dynamical positioning.
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(This article belongs to the Section Ocean Engineering)
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Open AccessArticle
USV Path Planning in a Hybrid Map Using a Genetic Algorithm with a Feedback Mechanism
by
Hang Gao, Tingting Zhang, Zheming Zuo, Xuan Guo, Yang Long, Da Qiu and Song Liu
J. Mar. Sci. Eng. 2024, 12(6), 939; https://doi.org/10.3390/jmse12060939 - 3 Jun 2024
Abstract
Unmanned surface vehicles (USVs) often operate in real-world environments with long voyage distances and complex routes. The use of a single-grid map model presents challenges, such as the high computational costs for high-resolution maps and loss of environmental information for low-resolution maps. This
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Unmanned surface vehicles (USVs) often operate in real-world environments with long voyage distances and complex routes. The use of a single-grid map model presents challenges, such as the high computational costs for high-resolution maps and loss of environmental information for low-resolution maps. This article proposes an environmental modeling method using a hybrid map that combines topology units and grids. The approach involves calibrating key nodes based on the watershed skeleton line, constructing a topology map using these nodes, decomposing the original map into unit maps, converting each unit map into a grid map, and creating a hybrid map environment model that comprises topology maps, unit map sets, and grid map sets. Then, the article introduces an improved genetic algorithm, called Genetic Algorithm with Feedback (FGA), to address path planning in hybrid maps. Experimental results demonstrate that FGA has better computational efficiency than other algorithms in similar experimental environments. In hybrid maps, path planning with FGA reduces the path lengths and time consumption, and the paths are more logical, smooth, and continuous. These findings contribute to enhancing the quality of path planning and the practical value of USVs.
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(This article belongs to the Section Ocean Engineering)
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Applicability of Variable-Geometry Turbocharger for Diesel Generators under High Exhaust Back Pressure
by
Chien-Cheng Chen, Yuan-Liang Jeng and Shun-Chang Yen
J. Mar. Sci. Eng. 2024, 12(6), 938; https://doi.org/10.3390/jmse12060938 - 3 Jun 2024
Abstract
The exhaust back pressure of diesel engines is becoming increasingly higher nowadays. In order to keep discharging exhaust unhindered and operating smoothly under high exhaust back pressure, a large reduction in engine maximum brake output is often observed, as well as increased fuel
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The exhaust back pressure of diesel engines is becoming increasingly higher nowadays. In order to keep discharging exhaust unhindered and operating smoothly under high exhaust back pressure, a large reduction in engine maximum brake output is often observed, as well as increased fuel consumption and lower combustion efficiency with heavy exhaust smokes. In our previous study, “Applicability of Reducing Valve Timing Overlap for Diesel Engines under High Exhaust Back Pressure”, a reduced valve timing overlap of 12 °CA partially improves the brake output and BSFC for a fixed-geometry turbocharged diesel engine under high exhaust back pressures. A potential solution for restoring the brake output under high exhaust back pressures could be the use of variable-geometry turbochargers. In this study, a variable-geometry turbocharger is applied to a diesel engine to study the engine performance characteristics and applicability, especially the further improvement of brake output and the brake-specific fuel consumption of the engine. Continuing with the results of our previous research, a basic setting of 12 °CA for the valve timing overlap is set up for the subsequent engine performance simulations in this study (using GT-Power SW). Via simulation, exhaust back pressures of 25 kPa, 45 kPa, and 65 kPa gauge are studied for a turbocharged diesel engine. The results for the engine parameters, including brake output, brake-specific fuel consumption, compressor outlet temperature, turbine inlet temperature, intake air mass flow rate, and exhaust mass flow rate are analyzed. The results of the variable-geometry turbocharger, including turbocharger speed, pressure ratios and efficiencies of compressor and turbine are also analyzed. The results indicate that the brake output and brake-specific fuel consumption are effectively improved under full-load operation with an adequate variable-geometry turbocharger rack position. Operable ranges of rack position are also set up for different back pressures.
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(This article belongs to the Section Ocean Engineering)
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Revisiting the Serçe Limanı Sail Plan
by
Nathan Helfman, Josef Rott and Deborah Cvikel
J. Mar. Sci. Eng. 2024, 12(6), 937; https://doi.org/10.3390/jmse12060937 - 3 Jun 2024
Abstract
The reconstruction of the Serçe Limanı ship proposed a double-masted rig consisting of two sails with a total combined area of 100 m2. That proposal considered provenance evidence and appraised hydrodynamic and hydrostatic conditions. The current paper proposes an alternative rig
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The reconstruction of the Serçe Limanı ship proposed a double-masted rig consisting of two sails with a total combined area of 100 m2. That proposal considered provenance evidence and appraised hydrodynamic and hydrostatic conditions. The current paper proposes an alternative rig consisting of a single sail. By applying computational fluid analysis and hydrostatic stability software to evaluate hull resistance, sail propulsion, and heeling moments, it has been demonstrated that a sail of no less than 150 m2 was suited to propel the Serçe Limanı. One of the two suitable alternative sails tested has been selected.
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(This article belongs to the Special Issue Advanced Technologies for Maritime and Underwater Archaeology—2nd Edition)
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