Journal of Marine Science and Engineering

16 pages, 5249 KiB

Open AccessArticle

Application of the Trigonometric Polynomial Interpolation for the Estimation of the Vertical Eddy Viscosity Coefficient Based on the Ekman Adjoint Assimilation Model

by Xinping Wu, Minjie Xu, Guandong Gao, Baoshu Yin and Xianqing Lv

J. Mar. Sci. Eng. 2022, 10(8), 1165; https://doi.org/10.3390/jmse10081165 - 22 Aug 2022

Cited by 3 | Viewed by 1642

Abstract

In this study, a triangular polynomial interpolation (TPI) scheme was developed to estimate the vertical eddy viscosity coefficient (VEVC) on the basis of the Ekman model with adjoint assimilation. In the twin experiments, the advantages and disadvantages of estimating the VEVC using the [...] Read more.

In this study, a triangular polynomial interpolation (TPI) scheme was developed to estimate the vertical eddy viscosity coefficient (VEVC) on the basis of the Ekman model with adjoint assimilation. In the twin experiments, the advantages and disadvantages of estimating the VEVC using the TPI scheme under different factors are discussed. The results indicated that (1) the TPI scheme proves to be better than the cubic spline interpolation (CSI) and Cressman interpolation (CI) schemes; (2) the inversion results are more sensitive to observations from upper ocean layers than those from lower layers, and the TPI scheme is less likely to be influenced by missing data; (3) for various boundary layer depths, the inversion results of the TPI scheme remain consistent with the given distributions; (4) the inversion results can be influenced considerably by observational errors, and the TPI scheme is more resistant to noise than the CSI and CI schemes; and (5) the inversion accuracy of the TPI scheme can be improved by selecting the temporal wind stress drag coefficients. In practical experiments, the adjoint method with the TPI scheme was developed to estimate the Ekman currents by assimilating the observations from a buoy stationed in the Yellow Sea. The results showed the successful estimation of the VEVC and demonstrated that more precise current velocities can be obtained with this estimation scheme. In summary, this study provides a useful approach for the effective estimation of the VEVC. Full article

(This article belongs to the Special Issue Advanced Studies in Coastal Ocean Observation)

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17 pages, 2282 KiB

Open AccessArticle

Study of the Influence of Nonlinear Moments upon Intensity of Parametric Roll

by Victoria Semenova, Kirill Rozhdestvensky, Danil Albaev and Zin Min Htet

J. Mar. Sci. Eng. 2022, 10(8), 1164; https://doi.org/10.3390/jmse10081164 - 22 Aug 2022

Cited by 2 | Viewed by 1157

Abstract

Hydrodynamical analysis of the conditions for the occurrence of chaotic ship roll, leading in some cases to the capsizing of the vessel, showed that such conditions are most likely to occur in the zone of the main parametric resonance of the roll when [...] Read more.

Hydrodynamical analysis of the conditions for the occurrence of chaotic ship roll, leading in some cases to the capsizing of the vessel, showed that such conditions are most likely to occur in the zone of the main parametric resonance of the roll when its period is sequentially doubled, and subharmonic oscillations turn into chaotic ones. This circumstance necessitates special attention to the regime of parametric roll resonance, issues of its occurrence, development, and establishment as well as to the methods of calculation of its amplitudes. In the present paper, the study of the parametric ship roll is conducted on the basis of the Lugovsky formula. An account is taken of the additional nonlinear moments

{\bar{M}}_{X}^{23}

and

{\bar{M}}_{X}^{24}

, obtained through the application of the small parameter method. Presented are the calculation results for the parametric roll of five different ships performing motions at various course angles both with and without account of the aforementioned nonlinear moments. Demonstrated therewith is a significant influence of the nonlinear moments upon the maximum amplitudes of the parametric roll, especially in the case of beam waves. Full article

(This article belongs to the Section Ocean Engineering)

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11 pages, 2328 KiB

Open AccessArticle

Potential Short-Term Effects of Mine Tailings on Phytoplankton Assemblages in the Open Ocean

by Dong Han Choi, Jangyeon Yoo, Wonseok Yang, Jae Hoon Noh, Yeonjung Lee, Kongtae Ra, Kiseong Hyeong, Chan Min Yoo and Jisoo Park

J. Mar. Sci. Eng. 2022, 10(8), 1162; https://doi.org/10.3390/jmse10081162 - 22 Aug 2022

Cited by 3 | Viewed by 1526

Abstract

The disposal of mine tailings into the marine environment is considered an essential option to secure the economic efficiency of deep-sea mining, but it might adversely affects the ecosystem. To examine the potential impacts of tailing disposal from polymetallic nodules and polymetallic sulfide [...] Read more.

The disposal of mine tailings into the marine environment is considered an essential option to secure the economic efficiency of deep-sea mining, but it might adversely affects the ecosystem. To examine the potential impacts of tailing disposal from polymetallic nodules and polymetallic sulfide mines on phytoplankton communities, addition experiments of crushed fine particles into surface seawater were conducted in the open Indian Ocean and changes in chlorophyll a fluorescence and community composition were analyzed. The addition of tailings had serious adverse effects on phytoplankton fluorescence and photosynthetic activity, regardless of mine type. The adverse effects seemed to mainly be due to the physical properties of the mine tailings. These also showed discriminatory effects on phytoplankton, resulting in great changes in community composition. The results suggest that mine tailings could have significant adverse impacts on phytoplankton assemblages, but the degree of impact greatly varies depending on the phytoplankton groups. The discriminatory impacts would cause changes in biomass, community structure, and thus ecological function. Full article

(This article belongs to the Section Marine Environmental Science)

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19 pages, 3877 KiB

Open AccessArticle

Dynamic Neuro-Fuzzy Systems for Forecasting El Niño Southern Oscillation (ENSO) Using Oceanic and Continental Climate Parameters as Inputs

by Ming Ze Lee, Fatemeh Mekanik and Amin Talei

J. Mar. Sci. Eng. 2022, 10(8), 1161; https://doi.org/10.3390/jmse10081161 - 22 Aug 2022

Cited by 2 | Viewed by 1399

Abstract

El Niño Southern Oscillation is one of the significant phenomena that drives global climate variability, showing a relationship with extreme events. Reliable forecasting of ENSO phases can minimize the risks in many critical areas, including water supply, food security, health, and public safety [...] Read more.

El Niño Southern Oscillation is one of the significant phenomena that drives global climate variability, showing a relationship with extreme events. Reliable forecasting of ENSO phases can minimize the risks in many critical areas, including water supply, food security, health, and public safety on a global scale. This study develops an ENSO forecasting model using the dynamic evolving neural fuzzy inference system (DENFIS), an artificial intelligence-based data-driven algorithm. To forecast ENSO phases for 1, 2, and 3 months ahead, 42 years (1979–2021) of monthly data of 25 oceanic and continental climatic variables and ENSO-characterizing indices are used. The dataset includes 12 El Niño and 14 La Niña events, of which the latest 2 El Niño and 4 La Niña events are reserved for testing while the remaining data are used for training the model. The potential input variables to the model are short-listed using a cross-correlation analysis. Then a systematic input selection procedure is conducted to identify the best input combinations for the model. The results of this study show that the best performing combination of such climate variables could achieve up to 78.57% accuracy in predicting short-term ENSO phases (up to 3 months ahead). Heat content at 0 to 300 m of central equatorial Pacific shows promising performance in forecasting ENSO phases. Moreover, DENFIS was found to be a reliable tool for forecasting ENSO events using multiple oceanic and continental climate variables. Full article

(This article belongs to the Section Physical Oceanography)

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30 pages, 5550 KiB

Open AccessArticle

An Improved Hydraulic Power Take-Off Unit Based on Dual Fluid Energy Storage for Reducing the Power Fluctuation Problem in the Wave Energy Conversion System

by Mohd Afifi Jusoh, Zulkifli Mohd Yusop, Aliashim Albani, Muhamad Zalani Daud and Mohd Zamri Ibrahim

J. Mar. Sci. Eng. 2022, 10(8), 1160; https://doi.org/10.3390/jmse10081160 - 21 Aug 2022

Cited by 2 | Viewed by 1813

Abstract

The power take-off (PTO) stability is one of the most important concerns for wave energy converters (WECs). The PTO unit converts the mechanical energy produced by the wave absorber (WA) unit into useful electrical energy. Due to the drastic input energy variation of [...] Read more.

The power take-off (PTO) stability is one of the most important concerns for wave energy converters (WECs). The PTO unit converts the mechanical energy produced by the wave absorber (WA) unit into useful electrical energy. Due to the drastic input energy variation of real wave motions, the generated electrical power from the PTO unit significantly fluctuates and is potentially harmful to electrical and electronic appliances. This paper proposes an improved hydraulic PTO (HPTO) for the WECs. An improved HPTO unit comprises a dual high-pressure accumulator (HPA) module and fluid energy control (FEC) module, which significantly enhances the generated electrical power from the generator under irregular wave circumstances. A complete model of wave absorber device with conventional and improved HPTO units was built in MATLAB/Simulink using a Simscape fluids toolbox. The parameters of the FEC control strategy were optimized using a genetic algorithm. The improved HPTO unit model was simulated with five irregular wave inputs to evaluate its performance in irregular conditions. The effects of the HPA pressure constraints on the improved HPTO unit performance were also investigated. Overall, the simulation results indicate that the improved HPTO unit was able to generate a stable power up to 87.3% of WECs in an irregular sea state. Full article

(This article belongs to the Special Issue Optimization and Energy Maximizing Control Systems for Wave Energy Converters II)

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13 pages, 4688 KiB

Open AccessArticle

Investigations on the Effectiveness of Protection Methods for a Submarine Pipeline Exposed to the Impact of a Falling Anchor

by Ciheng Zhang, Zhipeng Zang, Ming Zhao, Yanfei Chen and Jinfeng Zhang

J. Mar. Sci. Eng. 2022, 10(8), 1159; https://doi.org/10.3390/jmse10081159 - 21 Aug 2022

Viewed by 1380

Abstract

The occurrence of a buried submarine pipeline crossing a channel becoming damaged by the impact of a falling anchor is becoming more common. It is important to analyze the dynamic response of pipelines exposed to such impact and develop effective protection methods to [...] Read more.

The occurrence of a buried submarine pipeline crossing a channel becoming damaged by the impact of a falling anchor is becoming more common. It is important to analyze the dynamic response of pipelines exposed to such impact and develop effective protection methods to ensure the safe operation of the pipelines exposed to the impact of falling anchors. In this study, different protection methods, including pure rock, concrete mattress + rock, concrete mattress + rock + rubber pad, and compound flexible pad + rock, are physically tested. The strains at the impacting point and along the pipeline were measured with the fiber Bragg grating (FBG) sensors. The effectiveness of the protection methods is analyzed based on the maximum strain and its affected length on the pipeline. Then, a theoretical model is established to analyze the deformation and strain of a pipeline. Through curve-fitting the experimental results, the bearing capacity coefficients for different protection methods are determined. The protection method of compound flexible pad + rock has the best performance to protect the pipeline from the impact of a falling anchor. Full article

(This article belongs to the Special Issue Advances in Marine and Offshore Hydrodynamic Design)

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20 pages, 4229 KiB

Open AccessArticle

Importance of Pre-Storm Morphological Factors in Determination of Coastal Highway Vulnerability

by Jorge E. Pesantez, Adam Behr and Elizabeth Sciaudone

J. Mar. Sci. Eng. 2022, 10(8), 1158; https://doi.org/10.3390/jmse10081158 - 21 Aug 2022

Viewed by 1579

Abstract

This work considers a database of pre-storm morphological factors and documented impacts along a coastal roadway. Impacts from seven storms, including sand overwash and pavement damage, were documented via aerial photography. Pre-storm topography was examined to parameterize the pre-storm morphological factors likely to [...] Read more.

This work considers a database of pre-storm morphological factors and documented impacts along a coastal roadway. Impacts from seven storms, including sand overwash and pavement damage, were documented via aerial photography. Pre-storm topography was examined to parameterize the pre-storm morphological factors likely to control whether stormwater levels and waves impact the road. Two machine learning techniques, K-nearest neighbors (KNN) and ensemble of decision trees (EDT), were employed to identify the most critical pre-storm morphological factors in determining the road vulnerability, expressed as a binary variable to impact storms. Pre-processing analysis was conducted with a correlation analysis of the predictors’ data set and feature selection subroutine for the KNN classifier. The EDTs were built directly from the data set, and feature importance estimates were reported for all storm events. Both classifiers report the distances from roadway edge-of-pavement to the dune toe and ocean as the most important predictors of most storms. For storms approaching from the bayside, the width of the barrier island was the second most important factor. Other factors of importance included elevation of the dune toe, distance from the edge of pavement to the ocean shoreline, shoreline orientation (relative to predominant wave angle), and beach slope. Compared to previously reported optimization techniques, both machine learning methods improved using pre-storm morphological data to classify highway vulnerability based on storm impacts. Full article

(This article belongs to the Special Issue Performance of Transportation Systems Subjected to Extreme Hydrodynamic Events)

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18 pages, 5068 KiB

Open AccessArticle

Response of Temperature to Successive Typhoons in the South China Sea

by Shuzong Han, Mingjie Wang and Bo Peng

J. Mar. Sci. Eng. 2022, 10(8), 1157; https://doi.org/10.3390/jmse10081157 - 21 Aug 2022

Cited by 3 | Viewed by 1500

Abstract

Typhoons are serious natural disasters in coastal areas. During the summer of 2011, successive typhoons Nesat and Nalgae appeared in the South China Sea, providing a unique opportunity for us to study the response of the upper ocean to successive typhoons. We comprehensively [...] Read more.

Typhoons are serious natural disasters in coastal areas. During the summer of 2011, successive typhoons Nesat and Nalgae appeared in the South China Sea, providing a unique opportunity for us to study the response of the upper ocean to successive typhoons. We comprehensively use satellite data and COAWST model data to explore the effects of successive typhoons on the temperature structure of the South China Sea. Nesat caused the sea surface temperature to decrease by up to 4.4 °C on the right side of the typhoon path, and the ensuing Nalgae caused the temperature to decrease by up to 2.2 °C. Because Nesat had already cooled the ocean, the response to Nalgae was more to the left of the track than one would normally expect. The upwelling dominates the change in subsurface temperature. Based on the increase caused by Nesat, the isotherm was further raised by Nalgae. The isotherm rising amplitude is larger in the upper and deeper layer and is smaller in the middle layer in the depth range of 0–200 m. Heat budget analysis indicates that in the area close to the typhoon path, vertical diffusion is the main reason for the decrease in ocean surface temperature, while total advection suppresses the decrease in temperature. In the area with a larger distance from the typhoon path, vertical diffusion and total advection lead to the decrease in ocean surface temperature, and total advection will gradually contribute more to temperature change and become the dominant factor. On the right side of the typhoon track, the reduction of the contribution rate of vertical diffusion with distance from typhoon track is slower than that on the left side of the typhoon track. Whether Nesat or Nalgae, the intensity and depth of effects of vertical diffusion on the right side of typhoon path are greater than those on the left side of typhoon path, and the near-inertial periodic oscillation of local temperature change rate is more obvious. When the vertical diffusion is weak, the influence of vertical advection and horizontal advection is deeper. Moreover, the near-inertial periodic oscillation of the local temperature change occurs in lower depth after Nalgae passed through than that after Nesat. The typhoon intensity of the two typhoons shows the opposite change: the first typhoon increases, and the second typhoon weakens. Therefore, the special case of successive typhoons should be fully considered in typhoon prediction to improve accuracy. Full article

(This article belongs to the Section Physical Oceanography)

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24 pages, 16036 KiB

Open AccessArticle

Design and Performance Analysis of a Staggered Vernier Generator for Wave Power Generation

by Zhongyue Lu, Guoheng Wu, Mangkuan Wang, Zirong Luo and Jianzhong Shang

J. Mar. Sci. Eng. 2022, 10(8), 1156; https://doi.org/10.3390/jmse10081156 - 21 Aug 2022

Viewed by 1593

Abstract

In this paper, a staggered vernier generator suitable for a counter-rotating self-adaptable WEC is proposed to meet the energy demand of the small-scale engineering equipment in the deep sea. According to the vernier effect of the magnetic gear, the generator modulates the low-order [...] Read more.

In this paper, a staggered vernier generator suitable for a counter-rotating self-adaptable WEC is proposed to meet the energy demand of the small-scale engineering equipment in the deep sea. According to the vernier effect of the magnetic gear, the generator modulates the low-order rotating magnetic field generated by the rotation of the low-speed permanent magnet rotor into a high-order magnetic field rotating at a high speed, thereby realizing the acceleration of the generator magnetic field. A staggered structure permanent magnet vernier generator with 18 teeth/28 poles is designed. The main magnetic flux path on the staggered structure in the staggered vernier generator is analyzed, and the air-gap magnetic field distribution of the generator is analyzed with the help of numerical simulation software. The influence of different design parameters on the vernier generator is discussed. The staggered vernier structure can improve the main magnetic flux of the generator, reduce the magnetic flux leakage, and improve the performance of the generator without adding additional structures and materials. Full article

(This article belongs to the Section Marine Energy)

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17 pages, 3747 KiB

Open AccessArticle

A Realistic and Integrated Model for Evaluating Offshore Oil Development

by Rui Qiu, Zhuochao Li, Qin Zhang, Xin Yao, Shuyi Xie, Qi Liao and Bohong Wang

J. Mar. Sci. Eng. 2022, 10(8), 1155; https://doi.org/10.3390/jmse10081155 - 20 Aug 2022

Cited by 3 | Viewed by 3890

Abstract

With the rising consumption of oil resources, major oil companies around the world have increasingly engaged in offshore oil exploration and development, and offshore oil resources have accounted for an increasing proportion. Offshore oil engineering projects are capital intensive, and the development of [...] Read more.

With the rising consumption of oil resources, major oil companies around the world have increasingly engaged in offshore oil exploration and development, and offshore oil resources have accounted for an increasing proportion. Offshore oil engineering projects are capital intensive, and the development of offshore oil fields faces a tough battle, especially in a period of low oil prices. Thus, a comprehensive evaluation model is highly needed to help assess economic benefits and provide meaningful and valuable information for operators and investors to make sensible decisions. This study firstly proposed a realistic and integrated evaluation model for offshore oil development based on actual historical project data. This evaluation model incorporated modules from the underwater system to the platform system and processes from oil reservoir extraction to oil, gas and water treatment. The uncertain parameters in the evaluation process are dealt with by sensitivity analysis and Monte Carlo simulation. The proposed model is applied to a typical offshore oil development project in Bohai Bay, China. The results reveal that the recovery factor and oil price have the greatest impact on the economic benefits. In the case of deterministic analysis, the breakeven oil price of the project is 40.59 USD/bbl. After considering the uncertainty of project parameters, the higher the oil price, the greater the probability of NPV > 0. When the oil price is higher than 70 USD/bbl, even with uncertain project parameters, the probability of NPV > 0 can still be as high as 97.39%. Full article

(This article belongs to the Section Ocean Engineering)

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18 pages, 6285 KiB

Open AccessArticle

Fusing XGBoost and SHAP Models for Maritime Accident Prediction and Causality Interpretability Analysis

by Cheng Zhang, Xiong Zou and Chuan Lin

J. Mar. Sci. Eng. 2022, 10(8), 1154; https://doi.org/10.3390/jmse10081154 - 20 Aug 2022

Cited by 12 | Viewed by 2373

Abstract

In order to prevent safety risks, control marine accidents and improve the overall safety of marine navigation, this study established a marine accident prediction model. The influences of management characteristics, environmental characteristics, personnel characteristics, ship characteristics, pilotage characteristics, wharf characteristics and other factors [...] Read more.

In order to prevent safety risks, control marine accidents and improve the overall safety of marine navigation, this study established a marine accident prediction model. The influences of management characteristics, environmental characteristics, personnel characteristics, ship characteristics, pilotage characteristics, wharf characteristics and other factors on the safety risk of maritime navigation are discussed. Based on the official data of Zhejiang Maritime Bureau, the extreme gradient boosting (XGBoost) algorithm was used to construct a maritime accident classification prediction model, and the explainable machine learning framework SHAP was used to analyze the causal factors of accident risk and the contribution of each feature to the occurrence of maritime accidents. The results show that the XGBoost algorithm can accurately predict the accident types of maritime accidents with an accuracy, precision and recall rate of 97.14%. The crew factor is an important factor affecting the safety risk of maritime navigation, whereas maintaining the equipment and facilities in good condition and improving the management level of shipping companies have positive effects on improving maritime safety. By explaining the correlation between maritime accident characteristics and maritime accidents, this study can provide scientific guidance for maritime management departments and ship companies regarding the control or management of maritime accident prevention. Full article

(This article belongs to the Section Ocean Engineering)

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22 pages, 7604 KiB

Open AccessArticle

Recognition and Depth Estimation of Ships Based on Binocular Stereo Vision

by Yuanzhou Zheng, Peng Liu, Long Qian, Shiquan Qin, Xinyu Liu, Yong Ma and Ganjun Cheng

J. Mar. Sci. Eng. 2022, 10(8), 1153; https://doi.org/10.3390/jmse10081153 - 20 Aug 2022

Cited by 48 | Viewed by 2904

Abstract

To improve the navigation safety of inland river ships and enrich the methods of environmental perception, this paper studies the recognition and depth estimation of inland river ships based on binocular stereo vision (BSV). In the stage of ship recognition, considering the computational [...] Read more.

To improve the navigation safety of inland river ships and enrich the methods of environmental perception, this paper studies the recognition and depth estimation of inland river ships based on binocular stereo vision (BSV). In the stage of ship recognition, considering the computational pressure brought by the huge network parameters of the classic YOLOv4 model, the MobileNetV1 network was proposed as the feature extraction module of the YOLOv4 model. The results indicate that the mAP value of the MobileNetV1-YOLOv4 model reaches 89.25%, the weight size of the backbone network was only 47.6 M, which greatly reduced the amount of computation while ensuring the recognition accuracy. In the stage of depth estimation, this paper proposes a feature point detection and matching algorithm based on the ORB algorithm at sub-pixel level, that is, firstly, the FSRCNN algorithm was used to perform super-resolution reconstruction of the original image, to further increase the density of image feature points and detection accuracy, which was more conducive to the calculation of the image parallax value. The ships’ depth estimation results indicate that when the distance to the target is about 300 m, the depth estimation error is less than 3%, which meets the depth estimation needs of inland ships. The ship target recognition and depth estimation technology based on BSV proposed in this paper makes up for the shortcomings of the existing environmental perception methods, improves the navigation safety of ships to a certain extent, and greatly promotes the development of intelligent ships in the future. Full article

(This article belongs to the Topic Advances in Intelligent Construction, Operation and Maintenance)

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25 pages, 5169 KiB

Open AccessFeature PaperArticle

Subaqueous and Subaerial Beach Changes after Implementation of a Mega Nourishment in Front of a Sea Dike

by Anna Kroon, Matthieu de Schipper, Sierd de Vries and Stefan Aarninkhof

J. Mar. Sci. Eng. 2022, 10(8), 1152; https://doi.org/10.3390/jmse10081152 - 20 Aug 2022

Cited by 8 | Viewed by 2290

Abstract

Sandy nourishments can provide additional sediment to the coastal system to maintain its recreational or safety function under rising sea levels. These nourishments can be implemented at sandy beach systems, but can also be used to reinforce gray coastal infrastructure (e.g., dams, dikes, [...] Read more.

Sandy nourishments can provide additional sediment to the coastal system to maintain its recreational or safety function under rising sea levels. These nourishments can be implemented at sandy beach systems, but can also be used to reinforce gray coastal infrastructure (e.g., dams, dikes, seawalls). The Hondsbossche Dunes project is a combined shoreface, beach, and dune nourishment of 35 million m

^{3}

sand. The nourishment was built to replace the flood protection function of an old sea-dike while creating additional space for nature and recreation. This paper presents the evolution of this newly created sandy beach system in the first 5 years after implementation based on bathymetric and topographic surveys, acquired every three to six months. A significant coastline curvature is created by the nourishment leading to erosion in the central 7 km bordered by zones with accretion. However, over the five-year period, net volume losses from the project area were less than 5% of the initial nourished sand volume. The man-made cross-shore beach profile rapidly mimics the characteristics of adjacent beaches. The slope of the surfzone is adjusted within two winters to a similar slope. The initially wide beaches (i.e., up to 225 m) are reduced to about 100 m-wide. Simultaneously, the dune volume has increased and the dune foot migrated seaward at the entire nourished site, regardless of whether the subaqueous profile gained or lost sediment. Our results show that the Hondsbossche Dunes nourishment, built with a natural slope and wide beach, created a positive sediment balance in the dune for a prolonged period after placement. As such, natural forces in the years after implementation provided a significant contribution to the growth in dune volume and related safety against flooding. Full article

(This article belongs to the Special Issue Sediment Dynamics in Artificial Nourishments)

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17 pages, 8838 KiB

Open AccessArticle

Impacts of High-Density Suspended Aquaculture on Water Currents: Observation and Modeling

by Xuehai Liu and Xuelei Zhang

J. Mar. Sci. Eng. 2022, 10(8), 1151; https://doi.org/10.3390/jmse10081151 - 20 Aug 2022

Cited by 2 | Viewed by 1504

Abstract

Large-scale aquaculture activities in China have been rapidly developing in coastal waters, and they inevitably affect hydrodynamic structures and, hence, substance transportation. Predicting the effects is critical for understanding the environmental ecology and biochemical processes in these waters. To realize the solution, we [...] Read more.

Large-scale aquaculture activities in China have been rapidly developing in coastal waters, and they inevitably affect hydrodynamic structures and, hence, substance transportation. Predicting the effects is critical for understanding the environmental ecology and biochemical processes in these waters. To realize the solution, we conducted a field observation in Sungo Bay, which is an important aquaculture bay in China, and we developed a three-dimensional numerical model by arranging so-called porous structures, representing the aquaculture facilities, on grids of the culture layers. The energy-loss coefficients were specified to determine the momentum loss by the friction of the structures. We determined the appropriate coefficients for the oyster, scallop, and kelp cultures by using numerical simulation. According to the observation and model results, the aquaculture substantially weakened the current velocities in the culture layers and altered the vertical structures of the water currents. For this high-density and large-scale culture bay, the decrease rates of the current velocities in the culture layer were up to ~68%, ~65% and ~60% in the culture zones of oysters, scallops, and kelps, respectively. Bivalve cultures and kelp and bivalve cultures reduced the water-exchange ability of the bay by 33% and 50%, respectively. The method and results of this study provide a reference for studies on other aquaculture bays. Full article

(This article belongs to the Special Issue New Technologies and Methods in Coastal Observing)

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16 pages, 15337 KiB

Open AccessArticle

Prediction Method for Ocean Wave Height Based on Stacking Ensemble Learning Model

by Yu Zhan, Huajun Zhang, Jianhao Li and Gen Li

J. Mar. Sci. Eng. 2022, 10(8), 1150; https://doi.org/10.3390/jmse10081150 - 19 Aug 2022

Cited by 2 | Viewed by 1809

Abstract

Wave heights are important factors affecting the safety of maritime navigation. This study proposed a stacking ensemble learning method to improve the prediction accuracy of wave heights. We analyzed the correlation between wave heights and other oceanic hydrological features, according to eleven features, [...] Read more.

Wave heights are important factors affecting the safety of maritime navigation. This study proposed a stacking ensemble learning method to improve the prediction accuracy of wave heights. We analyzed the correlation between wave heights and other oceanic hydrological features, according to eleven features, such as measurement time, horizontal velocity, temperature, and pressure, as the model inputs. A fusion model consisting of two layers was established according to the principle of stacking ensemble learning. The first layer used the extreme gradient boosting algorithm, a light gradient boosting machine, random forest, and adaptive boosting to determine the deep relations between the wave heights and the input features. The second layer used a linear regression model to fit the relation between the first layer outputs and the actual wave heights, using the data from the four models of the first layer. The fusion model was trained based on the 5-fold cross-verification algorithm. This paper used real data to test the performances of the proposed fusion model, and the results showed that the mean absolute error and the mean squared error of the fusion model were at least 35.79% and 50.52% better than those of the four models. Full article

(This article belongs to the Topic Wind, Wave and Tidal Energy Technologies in China)

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19 pages, 7582 KiB

Open AccessArticle

Modern Techniques for Flood Susceptibility Estimation across the Deltaic Region (Danube Delta) from the Black Sea’s Romanian Sector

by Anca Crăciun, Romulus Costache, Alina Bărbulescu, Subodh Chandra Pal, Iulia Costache and Cristian Ștefan Dumitriu

J. Mar. Sci. Eng. 2022, 10(8), 1149; https://doi.org/10.3390/jmse10081149 - 19 Aug 2022

Cited by 2 | Viewed by 1521

Abstract

Floods have become more and more severe and frequent with global climate change. The present study focuses on the Black Sea’s immediate riparian area over which the Danube Delta extends. Due to the accelerated increase in the severity of floods, the vulnerability of [...] Read more.

Floods have become more and more severe and frequent with global climate change. The present study focuses on the Black Sea’s immediate riparian area over which the Danube Delta extends. Due to the accelerated increase in the severity of floods, the vulnerability of the deltaic areas is augmenting. Therefore, it is very important to adopt measures to mitigate the negative effects of these phenomena. The basis of the measures to limit the negative effects is the activity of identifying areas prone to flooding. Thus, this research paper presents a methodology for estimating flood susceptibility using the Analytical Hierarchy Process (AHP) and Fuzzy-Analytical Hierarchy Process (FAHP) models. To determine the susceptibility to these natural risk phenomena, the following eight flood predictors were taken into account: slope, elevation, altitude above channel, land use, hydrological soil group, lithology distance from the river, and distance from water bodies. Furthermore, the weights that each flood predictor has in terms of determining flood susceptibility were determined through the previously mentioned models. The results revealed that the slope is the most important predictor, followed by elevation, distance from the river, and land use. These weights were used in the GIS environment to evaluate the susceptibility to floods from a spatial point of view. The areas with a high/very high value for these phenomena occupy over 70% of the surface of the Danube Delta. Full article

(This article belongs to the Section Marine Hazards)

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22 pages, 4878 KiB

Open AccessArticle

Spectral Kinetic-Energy Fluxes in the North Pacific: Definition Comparison and Normal- and Shear-Strain Decomposition

by Yi Yang and Ru Chen

J. Mar. Sci. Eng. 2022, 10(8), 1148; https://doi.org/10.3390/jmse10081148 - 19 Aug 2022

Viewed by 1921

Abstract

The spectral kinetic-energy flux is an effective tool to analyze the kinetic-energy transfer across a range of length scales, also known as the kinetic-energy cascade. Three methods to calculate spectral energy fluxes have been widely used, hereafter the Π_A, Π_F [...] Read more.

The spectral kinetic-energy flux is an effective tool to analyze the kinetic-energy transfer across a range of length scales, also known as the kinetic-energy cascade. Three methods to calculate spectral energy fluxes have been widely used, hereafter the Π_A, Π_F, and Π_Q definitions. However, the relations among these three definitions have not been examined in detail. Moreover, the respective contribution of the normal strain and shear strain of the flow field to kinetic-energy cascade has not been estimated before. Here, we use the kinetic energy equations to rigorously compare these definitions. Then, we evaluate the spectral energy fluxes, as well as its decomposition into the normal-strain and shear-strain components for the North Pacific, using a dynamically consistent global eddying state estimate. We find that the data must be preprocessed first to obtain stable results from the Π_F and Π_Q definitions, but not for the Π_A definition. For the upper 500 m of the North Pacific, in the wavenumber ranges with inverse kinetic-energy cascade, both the normal and shear-strain flow components contribute significantly to the spectral energy fluxes. However, at high wavenumbers, the dominant contributor to forward kinetic-energy cascade is the normal-strain component. These results should help shed light on the underlying mechanism of inverse and forward energy cascades. Full article

(This article belongs to the Section Physical Oceanography)

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20 pages, 777 KiB

Open AccessArticle

Research on the Evaluation of Logistics Efficiency in Chinese Coastal Ports Based on the Four-Stage DEA Model

by Hui Li, Linli Jiang, Jianan Liu and Dandan Su

J. Mar. Sci. Eng. 2022, 10(8), 1147; https://doi.org/10.3390/jmse10081147 - 19 Aug 2022

Cited by 8 | Viewed by 2452

Abstract

In the context of economic globalization, coastal port logistics has gradually become a focus of economic development, and the proper management of coastal port logistics performance is the main way to realize the high-efficiency operation of coastal ports, drives the direct economic development [...] Read more.

In the context of economic globalization, coastal port logistics has gradually become a focus of economic development, and the proper management of coastal port logistics performance is the main way to realize the high-efficiency operation of coastal ports, drives the direct economic development of the hinterland, and enhances import and export trade market competitiveness. Accordingly, this study was aimed to measure port logistics efficiency and explore its path of improvement for China’s coastal ports during the 2014–2018 period with a four-stage DEA model, including a Tobit model. The results of this study show that most of the coastal ports in China have emphasized their size more than their planning. During the study period, improving road network construction and the economic level in hinterland port cities was conducive to improving port logistics efficiency, but tertiary industry investment and foreign trade levels were negatively correlated with coastal port logistics efficiency. Full article

(This article belongs to the Special Issue Contemporary Shipping Logistics and Port Management)

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18 pages, 12518 KiB

Open AccessArticle

Modeling and Dynamic Analysis of a Triple-Tagline Anti-Swing System for Marine Cranes in an Offshore Environment

by Maokai Sun, Shenghai Wang, Guangdong Han, Lin An, Haiquan Chen and Yuqing Sun

J. Mar. Sci. Eng. 2022, 10(8), 1146; https://doi.org/10.3390/jmse10081146 - 19 Aug 2022

Cited by 3 | Viewed by 1928

Abstract

Payload lifting is inefficient and high-risk under rough sea conditions. Thus, it is not easy to achieve precise assembly, and the swing payload is liable to collide with other structures on deck and cause damage. In this paper, to explore the complex dynamic [...] Read more.

Payload lifting is inefficient and high-risk under rough sea conditions. Thus, it is not easy to achieve precise assembly, and the swing payload is liable to collide with other structures on deck and cause damage. In this paper, to explore the complex dynamic characteristics of a triple-tagline anti-swing system (TTAS) for marine cranes in an offshore environment, an irregular wave model was first integrated into a dynamic system model of TTAS, and the TTAS for offshore payload lifting was simplified as a constrained-pendulum system with moving base excitations. Further, the dynamic system model was established by applying the methods in robotics. Meanwhile, the dynamic characteristics were simulated and analyzed using Matlab/Simulink. The simulation results show that the in-plane angle and out-of-plane angle of the payload can be effectively suppressed, and the range of the two-dimensional trajectory of the payload is greatly reduced. The research results provide a theoretical basis for optimizing the mechanical structures of TTAS or similar equipment. Full article

(This article belongs to the Section Ocean Engineering)

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18 pages, 5055 KiB

Open AccessArticle

Radiation Hazard from Natural Radioactivity in the Marine Sediment of Jeddah Coast, Red Sea, Saudi Arabia

by Bandar A. Al-Mur and Ahmed Gad

J. Mar. Sci. Eng. 2022, 10(8), 1145; https://doi.org/10.3390/jmse10081145 - 19 Aug 2022

Cited by 6 | Viewed by 2780

Abstract

Marine sediment samples were collected along the Jeddah coast, Red Sea, Saudi Arabia, in order to assess radiation hazards and the exposure to human and marine living organisms. Using collaborative techniques, grain size, mineralogical characteristics, and natural radioactivity were investigated. To examine the [...] Read more.

Marine sediment samples were collected along the Jeddah coast, Red Sea, Saudi Arabia, in order to assess radiation hazards and the exposure to human and marine living organisms. Using collaborative techniques, grain size, mineralogical characteristics, and natural radioactivity were investigated. To examine the influence of sediment characteristics over the distribution of the measured radionuclides, resulting data were statistically processed by using multivariate analyses. ²³⁸U, ²³²Th, and ⁴⁰K levels were specified to be 19.50, 9.38, and 403.31 Bq kg⁻¹, respectively. Radionuclides distributions were affected by sediment mud content, organic matter, and heavy minerals index. The calculated radiation risk parameters are within the safe range and lower than the global average. Natural radiation from these marine sediments is normal and poses no significant radiological risk to the public or marine living organisms. The natural radioactivity of the marine sediment in this Jeddah coastline will have to be monitored on a regular basis to avoid overexposure to the residents. Full article

(This article belongs to the Special Issue Environmental Radioactivity in the Ocean)

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18 pages, 2979 KiB

Open AccessArticle

Study on Small Samples Active Sonar Target Recognition Based on Deep Learning

by Yule Chen, Hong Liang and Shuo Pang

J. Mar. Sci. Eng. 2022, 10(8), 1144; https://doi.org/10.3390/jmse10081144 - 19 Aug 2022

Cited by 7 | Viewed by 2198

Abstract

Underwater target classification methods based on deep learning suffer from obvious model overfitting and low recognition accuracy in the case of small samples and complex underwater environments. This paper proposes a novel classification network (EfficientNet-S) based on EfficientNet-V2S. After optimization with model scaling, [...] Read more.

Underwater target classification methods based on deep learning suffer from obvious model overfitting and low recognition accuracy in the case of small samples and complex underwater environments. This paper proposes a novel classification network (EfficientNet-S) based on EfficientNet-V2S. After optimization with model scaling, EfficientNet-S significantly improves the recognition accuracy of the test set. As deep learning models typically require very large datasets to train millions of model parameter, the number of underwater target echo samples is far more insufficient. We propose a deep convolutional generative adversarial network (SGAN) based on the idea of group padding and even-size convolution kernel for high-quality data augmentation. The results of anechoic pool experiments show that our algorithm effectively suppresses the overfitting phenomenon, achieves the best recognition accuracy of 92.5%, and accurately classifies underwater targets based on active echo datasets with small samples. Full article

(This article belongs to the Special Issue Application of Sensing and Machine Learning to Underwater Acoustic)

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19 pages, 7217 KiB

Open AccessArticle

YOLO-Submarine Cable: An Improved YOLO-V3 Network for Object Detection on Submarine Cable Images

by Yue Li, Xueting Zhang and Zhangyi Shen

J. Mar. Sci. Eng. 2022, 10(8), 1143; https://doi.org/10.3390/jmse10081143 - 18 Aug 2022

Cited by 14 | Viewed by 2731

Abstract

Due to the strain on land resources, marine energy development is expanding, in which the submarine cable occupies an important position. Therefore, periodic inspections of submarine cables are required. Submarine cable inspection is typically performed using underwater vehicles equipped with cameras. However, the [...] Read more.

Due to the strain on land resources, marine energy development is expanding, in which the submarine cable occupies an important position. Therefore, periodic inspections of submarine cables are required. Submarine cable inspection is typically performed using underwater vehicles equipped with cameras. However, the motion of the underwater vehicle body, the dim light underwater, and the property of light propagation in water lead to problems such as the blurring of submarine cable images, the lack of information on the position and characteristics of the submarine cable, and the blue–green color of the images. Furthermore, the submarine cable occupies a significant portion of the image as a linear entity. In this paper, we propose an improved YOLO-SC (YOLO-Submarine Cable) detection method based on the YOLO-V3 algorithm, build a testing environment for submarine cables, and create a submarine cable image dataset. The YOLO-SC network adds skip connections to feature extraction to make the position information of submarine cables more accurate, a top-down downsampling structure in multi-scale special fusion to reduce the network computation and broaden the network perceptual field, and lightweight processing in the prediction network to accelerate the network detection. Under laboratory conditions, we illustrate the effectiveness of these modifications through ablation studies. Compared to other algorithms, the average detection accuracy of the YOLO-SC model is increased by up to 4.2%, and the average detection speed is decreased by up to 1.616 s. The experiments demonstrate that the YOLO-SC model proposed in this paper has a positive impact on the detection of submarine cables. Full article

(This article belongs to the Special Issue Advances in Autonomous Underwater Robotics Based on Machine Learning)

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15 pages, 5155 KiB

Open AccessArticle

Normalized Stress–Strain Behavior of Deep-Sea Soft Soils in the Northern South China Sea

by Ying Yang, Hailei Kou, Zhenghui Li, Yonggang Jia and Chaoqi Zhu

J. Mar. Sci. Eng. 2022, 10(8), 1142; https://doi.org/10.3390/jmse10081142 - 18 Aug 2022

Cited by 5 | Viewed by 1725

Abstract

The study of the physical and mechanical properties of marine soil is of great importance for marine geohazard prediction, submarine energy extraction, and submarine foundation design. In this study, a series of basic geotechnical tests and triaxial compression tests are performed on samples [...] Read more.

The study of the physical and mechanical properties of marine soil is of great importance for marine geohazard prediction, submarine energy extraction, and submarine foundation design. In this study, a series of basic geotechnical tests and triaxial compression tests are performed on samples taken from the Shenhu sea area in the South China Sea (SCS). Physical and mechanical properties, particularly normalized stress–strain behavior, are investigated. The microstructural and mineralogical characterization is carried out, through scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results indicated that the sample could be classified as high-plasticity silt (MH) with high water content and high compressibility, that the soil has the highest quartz content in its mineral composition, a loose skeleton composed of flocculent structures under the microscope and is distributed with the remains of marine organisms. Furthermore, a new stress–strain-normalized condition is theoretically derived, based on the hyperbola function. In this condition, the concept of standard normalized factor, which is defined as the ultimate value of principal stress difference, is introduced. Meanwhile, the normalized stress–strain relationship of soft soil from the SCS is established under consolidated undrained conditions and the results of the model are compared with the experimental results, with a good normalization effect. It is believed that the work presented in this paper could contribute to the design and construction of offshore engineering. Full article

(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)

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24 pages, 3463 KiB

Open AccessArticle

The AUV-Follower Control System Based on the Prediction of the AUV-Leader Movement Using Data from the Onboard Video Camera

by Dmitry Yukhimets and Vladimir Filaretov

J. Mar. Sci. Eng. 2022, 10(8), 1141; https://doi.org/10.3390/jmse10081141 - 18 Aug 2022

Cited by 2 | Viewed by 1342

Abstract

The paper proposes a new method for the synthesis of spatial motion control systems of the AUV-leader and a group of AUV-followers during their cooperative movement in a desired formation. This system allows the provision of an accurate positioning of the followers relative [...] Read more.

The paper proposes a new method for the synthesis of spatial motion control systems of the AUV-leader and a group of AUV-followers during their cooperative movement in a desired formation. This system allows the provision of an accurate positioning of the followers relative to the leader using information received with a low frequency only from their onboard video cameras. To improve the accuracy of the created system it proposes a method of estimation of the parameters of the movement of the AUV-leader (its speeds and accelerations) to predict its movement relative to the AUV-follower in the time intervals between the updates of information received from video cameras. Full article

(This article belongs to the Special Issue Navigation, Modelling and Control of Multiple Marine Autonomous Vehicles)

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19 pages, 9040 KiB

Open AccessArticle

A Ship Firefighting Training Simulator with Physics-Based Smoke

by Rui Tao, Hongxiang Ren and Yi Zhou

J. Mar. Sci. Eng. 2022, 10(8), 1140; https://doi.org/10.3390/jmse10081140 - 18 Aug 2022

Cited by 3 | Viewed by 1996

Abstract

Under the current background of navigation education, students generally lack a comprehensive grasp of ship firefighting equipment’s operation. Therefore, we develop a novel ship firefighting training simulator with a multi-sensory human–computer interaction function for teaching and training marine students. In the simulator, we [...] Read more.

Under the current background of navigation education, students generally lack a comprehensive grasp of ship firefighting equipment’s operation. Therefore, we develop a novel ship firefighting training simulator with a multi-sensory human–computer interaction function for teaching and training marine students. In the simulator, we consider a container ship of 1.8w containers as the prototype ship, and the entire ship models are built using three-dimensional modeling technology. We design various interactive modes and realize a full-process operation simulation of several standard ship firefighting equipment. Furthermore, we propose a purely Lagrangian vortex dynamics framework to simulate smoke and flame in fire scenarios. In this framework, we model fluids using velocity and vorticity fields discretized on discrete vortex segments. The main components of the framework include a stable geometric stretching solution and particle strength exchange method for solving the diffusion term. The simulation results show that the simulator has good behavioral realism and scene immersion and can be applied to ship firefighting training. To the best of our knowledge, this is the first study on real-time smoke simulation using a physics-based method in a firefighting training simulator. Full article

(This article belongs to the Special Issue Recent Advances in Particle/Grid-Based Methods and Applications in Marine and Ocean Engineering)

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15 pages, 1332 KiB

Open AccessReview

A Review on Recent Development of Numerical Modelling of Local Scour around Hydraulic and Marine Structures

by Ming Zhao

J. Mar. Sci. Eng. 2022, 10(8), 1139; https://doi.org/10.3390/jmse10081139 - 18 Aug 2022

Cited by 13 | Viewed by 2775

Abstract

This paper reviews the recent development of numerical modelling of local scour around hydraulic and marine structures. The numerical models for simulating local scour are classified into five categories: sediment transport rate models, two-phase models, CFD-DEM models, equilibrium scour models and depth-averaged models. [...] Read more.

This paper reviews the recent development of numerical modelling of local scour around hydraulic and marine structures. The numerical models for simulating local scour are classified into five categories: sediment transport rate models, two-phase models, CFD-DEM models, equilibrium scour models and depth-averaged models. The sediment transport rate models are the most popularly used models because of their high calculation speed and availability of empirical formulae for predicting sediment transport rates. Two-phase models were developed to simulate sediment transport in the format of sheet flow under strong current velocity or strong turbulence. The CFD-DEM model simulates the motion of every individual sediment particle. Its speed is the slowest, but it provides the opportunity to understand fundamental mechanisms of flow–particle interaction and particle–particle interaction using small-scale simulations. Equilibrium scour models predict the final scour profile at the equilibrium stage but cannot predict scour history. The depth-averaged models that were developed early are not recommended for local scour problems because they are not able to predict three-dimensional features around structures. Although many numerical models have been developed and many studies have been conducted to investigate local scour, some challenging problems remain to be solved, for example, the effects from scaling and sediment gradation. In addition, people’s understanding of local scour of cohesive sand is still very shallow, and more experimental and numerical research in this area is needed. Full article

(This article belongs to the Section Ocean Engineering)

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30 pages, 9188 KiB

Open AccessArticle

Sensitivities in Wind Driven Spectral Wave Modelling for the Belgian Coast

by Frans van Eeden, Georgios Klonaris, Jeffrey Verbeurgt, Peter Troch and Alain De Wulf

J. Mar. Sci. Eng. 2022, 10(8), 1138; https://doi.org/10.3390/jmse10081138 - 18 Aug 2022

Viewed by 1365

Abstract

This paper presents the analysis of spectral wind-wave modelling (using SWAN) of the North Sea focusing on the modelled wave parameters along the Belgian coast. Two wind databases were used to drive the model: ECMWF-ERA5 reanalysis and the Dutch Offshore Wind Atlas. The [...] Read more.

This paper presents the analysis of spectral wind-wave modelling (using SWAN) of the North Sea focusing on the modelled wave parameters along the Belgian coast. Two wind databases were used to drive the model: ECMWF-ERA5 reanalysis and the Dutch Offshore Wind Atlas. The models were calibrated with measured data at various stations along the Belgian coastline. The accuracy in terms of wave parameter statistics was compared for the calibrated and uncalibrated models. It was found that a calibrated SWAN model does, in general, produce more accurate results when compared to measured data for stations along the Belgian coastline even though not by any significant margin. Comparing the two wind databases, on the modelling scale conducted in this study, there is no advantage observed in using a spatially finer scale wind database over a coarser database to force the model. The grid sizes were varied in the models and marginal differences were observed in the modelled data. The long-term extreme value statistics were calculated for various grid sizes and compared to published values. It is shown that the extreme value statistics are relatively insensitive to the grid density and thus much time can be saved on long-term modelling on this model scale. In addition, a benefit to the practise of grid nesting is demonstrated when considering complex bathymetric effects that have an influence on wave transformation in the shallower areas of the coast, especially along the Belgian coastline demarcated with its numerous sandbanks. Full article

(This article belongs to the Section Coastal Engineering)

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8 pages, 1686 KiB

Open AccessArticle

Tsunami Distribution Functions along the Coast: Extended

by Ira Didenkulova, Andrey Zaitsev and Efim Pelinovsky

J. Mar. Sci. Eng. 2022, 10(8), 1137; https://doi.org/10.3390/jmse10081137 - 18 Aug 2022

Cited by 2 | Viewed by 1351

Abstract

The distribution of tsunami runup heights along the coast is studied both theoretically and experimentally using observation data of historical tsunami from 1992 to 2018. The physical mechanisms leading to the lognormal distribution of tsunami runup heights along the coast are discussed, and [...] Read more.

The distribution of tsunami runup heights along the coast is studied both theoretically and experimentally using observation data of historical tsunami from 1992 to 2018. The physical mechanisms leading to the lognormal distribution of tsunami runup heights along the coast are discussed, and its statistical moments are calculated. It is shown that the lognormal distribution describes well the measurements of tsunami characteristics over the past 30 years. Special attention is paid to the multi-source 2018 Palu–Sulawesi tsunami, which was generated by an earthquake with magnitude 7.5 and numerous subsequent landslides. It is shown that even in this special case the lognormal distribution is a rather good approximation. Full article

(This article belongs to the Special Issue “Coastal Dynamics, Hazards, and Numerical Modelling” in Memory of Prof. Byung Ho Choi)

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14 pages, 3742 KiB

Open AccessArticle

Towards an Algorithm for Retrieval of the Parameters of the Marine Atmospheric Boundary Layer at High Wind Speeds Using Collocated Aircraft and Satellite Remote Sensing

by Evgeny Poplavsky, Nikita Rusakov, Olga Ermakova, Daniil Sergeev and Yuliya Troitskaya

J. Mar. Sci. Eng. 2022, 10(8), 1136; https://doi.org/10.3390/jmse10081136 - 18 Aug 2022

Cited by 5 | Viewed by 1779

Abstract

A method has been developed for the retrieval of the atmospheric boundary layer parameters in tropical cyclones, namely the dynamic speed, the wind speed at a 10 m height, and the roughness parameter. For the analysis, the wind speed profiles were obtained from [...] Read more.

A method has been developed for the retrieval of the atmospheric boundary layer parameters in tropical cyclones, namely the dynamic speed, the wind speed at a 10 m height, and the roughness parameter. For the analysis, the wind speed profiles were obtained from NOAA GPS-dropsondes and collocated with the data from the Stepped-Frequency Microwave Radiometer (SFMR). The parameters of the atmospheric boundary layer from the GPS-dropsonde data were obtained by taking into account the self-similarity of the velocity defect profile. The emissivity, determined from the radiometric measurement data, was calibrated to the field data from the GPS-dropsondes. Empirical relations between the wind speed, dynamic wind speed, and aerodynamic drag coefficient with the surface emissivity have been proposed. Based on a comparison of the measured dynamic parameters and the surface emissivity, empirical formulas have also been proposed. From an analysis of cross-polarized Sentinel-1 SAR images and collocated SFMR measurements for hurricanes Irma (2017/09/07) and Maria (2017/09/21 and 2017/09/23), we have obtained the dependences of the NRCS on the ocean surface emissivity, surface wind speed, and friction velocity. These results could potentially be used to improve the algorithm for the retrieval of boundary layer parameters in tropical cyclones from remote sensing data. Full article

(This article belongs to the Special Issue Satellite Monitoring of Ocean)

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11 pages, 1261 KiB

Open AccessArticle

Idiomarina sp. Isolates from Cold and Temperate Environments as Biosurfactant Producers

by Carmen Rizzo, Maria Papale and Angelina Lo Giudice

J. Mar. Sci. Eng. 2022, 10(8), 1135; https://doi.org/10.3390/jmse10081135 - 17 Aug 2022

Cited by 5 | Viewed by 1501

Abstract

Background: The cold-adapted Idiomarina sp. 185 from Antarctic shoreline sediment and the mesophilic Idiomarina sp. A19 from the brackish Lake Faro (Italy) were screened for their efficiency in biosurfactant production by a temperature-mediated approach, when grown in rich culture medium and mineral medium [...] Read more.

Background: The cold-adapted Idiomarina sp. 185 from Antarctic shoreline sediment and the mesophilic Idiomarina sp. A19 from the brackish Lake Faro (Italy) were screened for their efficiency in biosurfactant production by a temperature-mediated approach, when grown in rich culture medium and mineral medium supplemented with biphenyl. Methods: oxidation of polychlorobiphenyls and standard screening tests were performed, i.e., E₂₄ index detection, surface tension measurement, blood agar plate and C-TAB agar plate. Results: During incubation in rich medium, the strain Idiomarina sp. A19 produced an excellent stable emulsion, recording an E₂₄ of 73.5%. During growth in mineral medium, isolates showed good efficiency in at least one performed condition by showing species-specific differences related to optimum temperature. In the presence of biphenyl, both Idiomarina isolates created stable emulsions (E₂₄ ≈ 47.5 and 35%, respectively), as well as surface tension reductions of 30.05 and 35.5 mN/m, respectively. Further differences between isolates were observed by phenotypic characterization. The genome mining approach on available deposited genome sequences for closest relatives offered further insights about the presence of genes for biphenyl degradation, especially for microorganisms derived from different extreme environments. Conclusions: Our results allowed for an interesting comparison which underlined differences in metabolic patterns and in the kinetics of BS production, probably due to the different origins of the strains. Full article

(This article belongs to the Section Marine Biology)

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