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J. Mar. Sci. Eng., Volume 10, Issue 12 (December 2022) – 240 articles

Cover Story (view full-size image): The use of modern high-powered internal combustion engines is inevitably associated with the risk of a fire or an explosion. The most important places where such risks occur are during the operation of a low-speed crosshead engine. Based on available sources, the frequency of explosions in the marine engine’s starting air manifolds is determined under real conditions. A cause-and-effect analysis of these explosions is carried out, and their root causes are identified. A probabilistic model of an explosion in the starting air manifold of a marine engine is built. The significance of each basic event is assessed to determine their individual impact on the explosion incident. View this paper
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14 pages, 5516 KiB  
Article
Modeling of Ship DC Power Grid and Research on Secondary Control Strategy
by Hong Zeng, Yuanhao Zhao, Xuming Wang, Taishan He and Jundong Zhang
J. Mar. Sci. Eng. 2022, 10(12), 2037; https://doi.org/10.3390/jmse10122037 - 19 Dec 2022
Cited by 2 | Viewed by 1381
Abstract
Compared to alternating current (AC) grids, direct current (DC) grids are becoming more and more popular. A power distribution approach is suggested in order to solve the issue of uneven power distribution of distributed generation (DG) in a ship DC microgrid. Power control [...] Read more.
Compared to alternating current (AC) grids, direct current (DC) grids are becoming more and more popular. A power distribution approach is suggested in order to solve the issue of uneven power distribution of distributed generation (DG) in a ship DC microgrid. Power control is carried out using a tracking differentiator (TD), while the output power change rate is not greater than the maximum power ramp rate permitted by the battery, and state-of-charge balance is attained quickly. The proposed strategy also reduces the communication pressure on the power grid. A distributed hierarchical control model of a DC microgrid based on a consensus algorithm is created in order to validate the suggested methodology. The simulation results demonstrate that the established model is capable of simulating the DC microgrid accurately, that the states of charge values of the five batteries gradually converge under the adjustment of the secondary strategy, and that the suggested strategy is reasonable and efficient. Full article
(This article belongs to the Section Ocean Engineering)
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31 pages, 26140 KiB  
Article
Comparison of Velocity Obstacle and Artificial Potential Field Methods for Collision Avoidance in Swarm Operation of Unmanned Surface Vehicles
by Hyun-Jae Jo, Su-Rim Kim, Jung-Hyeon Kim and Jong-Yong Park
J. Mar. Sci. Eng. 2022, 10(12), 2036; https://doi.org/10.3390/jmse10122036 - 19 Dec 2022
Cited by 2 | Viewed by 1767
Abstract
As the research concerning unmanned surface vehicles (USVs) intensifies, research on swarm operations is also being actively conducted. A swarm operation imitates the appearance of nature, such as ants, bees, and birds, in forming swarms, moving, and attacking in the search for food. [...] Read more.
As the research concerning unmanned surface vehicles (USVs) intensifies, research on swarm operations is also being actively conducted. A swarm operation imitates the appearance of nature, such as ants, bees, and birds, in forming swarms, moving, and attacking in the search for food. However, several problems are encountered in the USV swarm operation. One of these is the problem of collisions between USVs. A conflict between agents in a swarm can lead to operational failure and property loss. This study attempted to solve this problem. In this study, a virtual matrix approach was applied as a swarm operation. Velocity obstacle (VO) and artificial potential field (APF) methods were used and compared as algorithms for collision avoidance for USVs in a swarm when the formation is changed. For effective collision avoidance, evasive maneuvers should be performed at an appropriate time and location. Therefore, a closest point of approach (CPA)-based method, which considers both temporal and spatial factors, was used. The swarm operation was verified through a large-scale simulation in which 30 USVs changed their formation seven times in 3400 s. When comparing the averages of the distance, error to waypoint, and battery usage, no significant differences were noticed between the VO and APF methods. However, when comparing the cumulative time using the minimum distance, VO was demonstrably safer than APF, and VO completed the formation faster. In conclusion, both the APF and VO methods can evidently perform swarm operations without collisions. Full article
(This article belongs to the Special Issue Control and Stability of Ship Motions)
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11 pages, 2303 KiB  
Article
Laboratory Experiments on the Influence of the Wave Spectrum Enhancement Factor on a Rubble Mound Breakwater
by Hosny Bakali, Ismail Aouiche, Najat Serhir, Youssef Zahir, El hassan Ziane, Abderrazak Harti, Zakariae Zerhouni and Edward Anthony
J. Mar. Sci. Eng. 2022, 10(12), 2035; https://doi.org/10.3390/jmse10122035 - 19 Dec 2022
Viewed by 1374
Abstract
This paper experimentally explored the influence of the wave spectrum shape variation on breakwater design. The energy spectrum function generally considered for the design of coastal structures is the JONSWAP spectrum. The laboratory results were therefore used to assess the impact of changing [...] Read more.
This paper experimentally explored the influence of the wave spectrum shape variation on breakwater design. The energy spectrum function generally considered for the design of coastal structures is the JONSWAP spectrum. The laboratory results were therefore used to assess the impact of changing the spectrum shape parameter (PEF). We analysed armour stability and wave overtopping in a wave flume with a geometric similarity ratio of 1:30. The experimental results showed that the PEF has maximum influence on overtopping and wave pressures on the crown wall. For a PEF value of 3.3, overtopping was much higher (30% to 100% higher) than with a PEF of 1. Pressure on the crown wall was 20% higher with a PEF of 3.3 in comparison with that for a PEF equal to 1. The stability of the breakwater’s block armour is less sensitive to the PEF variation. Full article
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17 pages, 1963 KiB  
Article
Fleet Deployment Optimization for LNG Shipping Vessels Considering the Influence of Mixed Factors
by Zhongbin Zhao, Xifu Wang, Hao Wang, Suxin Cheng and Wei Liu
J. Mar. Sci. Eng. 2022, 10(12), 2034; https://doi.org/10.3390/jmse10122034 - 19 Dec 2022
Cited by 6 | Viewed by 2844
Abstract
Driven by China’s booming natural gas consumption market, LNG (Liquified Natural Gas) shipping import has grown rapidly. To facilitate scientific and efficient decision making on LNG shipping fleet deployment and the development of the LNG shipping industry, this article proposes an optimization model [...] Read more.
Driven by China’s booming natural gas consumption market, LNG (Liquified Natural Gas) shipping import has grown rapidly. To facilitate scientific and efficient decision making on LNG shipping fleet deployment and the development of the LNG shipping industry, this article proposes an optimization model to minimize annual fleet operating costs, including voyage cost, running cost, and capital cost. Under the consideration of the mixed factors of self-owned and time charter vessels, epidemic prevention and control, port congestion, transportation time cost, and evaporation loss, as well as navigation security and emergency situations, the validity and optimality of the model are demonstrated by the empirical example and the cost comparison between the conventional and optimized solution. The results show that this optimization model can reduce the total cost by 9.87%. Then, through sensitivity analysis, various significant factors affecting the operating costs of LNG shipping enterprises and their degrees of influence are determined. Based on the analysis of the relevant causes, some actionable countermeasures are recommended, including establishing a shipping price reciprocity mechanism and full chain investment planning, optimizing the inbound link to reduce invalid berthing time, strengthening the construction competitiveness and economy of scale of larger LNG ships, and building a combined dual resource pool transportation mode. This paper contributes to improving transregional maritime energy transport and management capacity, while further enhancing the energy security and development of port cities and their economic hinterlands. Full article
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15 pages, 1083 KiB  
Article
Learning-Based Nonlinear Model Predictive Controller for Hydraulic Cylinder Control of Ship Steering System
by Xiaolong Tang, Changjie Wu and Xiaoyan Xu
J. Mar. Sci. Eng. 2022, 10(12), 2033; https://doi.org/10.3390/jmse10122033 - 19 Dec 2022
Cited by 5 | Viewed by 2025
Abstract
The steering mechanism of ship steering gear is generally driven by a hydraulic system. The precise control of the hydraulic cylinder in the steering mechanism can be achieved by the target rudder angle. However, hydraulic systems are often described as nonlinear systems with [...] Read more.
The steering mechanism of ship steering gear is generally driven by a hydraulic system. The precise control of the hydraulic cylinder in the steering mechanism can be achieved by the target rudder angle. However, hydraulic systems are often described as nonlinear systems with uncertainties. Since the system parameters are uncertain and system performances are influenced by disturbances and noises, the robustness cannot be satisfied by approximating the nonlinear theory by a linear theory. In this paper, a learning-based model predictive controller (LB-MPC) is designed for the position control of an electro-hydraulic cylinder system. In order to reduce the influence of uncertainty of the hydraulic system caused by the model mismatch, the Gaussian process (GP) is adopted, and also the real-time input and output data are used to improve the model. A comparative simulation of GP-MPC and MPC is performed assuming that the interference and uncertainty terms are bounded. Consequently, the proposed control strategy can effectively improve the piston position quickly and precisely with multiple constraint conditions. Full article
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18 pages, 5900 KiB  
Article
Wave Transformation behind a Breakwater in Jukbyeon Port, Korea—A Comparison of TOMAWAC and ARTEMIS of the TELEMAC System
by Jong-Dae Do, Sang-Kwon Hyun, Jae-Youll Jin, Byunggil Lee, Weon-Mu Jeong, Kyong-Ho Ryu, Won-Dae Back, Jae-Ho Choi and Yeon S. Chang
J. Mar. Sci. Eng. 2022, 10(12), 2032; https://doi.org/10.3390/jmse10122032 - 19 Dec 2022
Cited by 1 | Viewed by 1566
Abstract
Severe shoreline erosions are commonly observed due to the side effects of breakwaters constructed to protect the habitat. These breakwaters can cause wave energy differences behind the structure due to diffraction, inducing longshore sediment transport and resulting in shoreline changes. Therefore, it is [...] Read more.
Severe shoreline erosions are commonly observed due to the side effects of breakwaters constructed to protect the habitat. These breakwaters can cause wave energy differences behind the structure due to diffraction, inducing longshore sediment transport and resulting in shoreline changes. Therefore, it is essential to correctly simulate the effect of wave transformation in the lee side of structures, but such studies reporting performance of models in the field have been relatively rare. In this study, two wave models of the TELEMAC system were used to investigate the accuracy of modeling the wave transformation effect in a lee area of a breakwater built to secure the harbor’s tranquility, near Jukbyeon Port in Korea, through comparisons with field observations. Two cases of wave conditions with different wave heights and directions were tested. In both cases, the TEL EMAC–ARTEMIS model had lower errors than TELEMAC–TOMAWAC at the onshore wave location, confirming that the phase-resolving ARTEMIS showed better performance in simulating the wave transformation than the phase-averaged TOMAWAC, as expected. However, ARTEMIS had slightly higher errors than TOMAWAC at the offshore location, probably due to the interference by reflected waves from the complex coastlines formed by the different coastal structures. The results also provide various implications learned from the numerical experiments, which can be usefully applied to engineering aspects, such as for the estimation of harbor tranquility. Full article
(This article belongs to the Special Issue Sandy Beach Erosion and Protection: Past, Present and Future)
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18 pages, 1897 KiB  
Article
Estimation of LNG Dolphin Capacity: Dolphins of Different Size in Republic of Korea
by Nam Kyu Park and Yohan An
J. Mar. Sci. Eng. 2022, 10(12), 2031; https://doi.org/10.3390/jmse10122031 - 19 Dec 2022
Cited by 1 | Viewed by 1200
Abstract
The LNG terminals are characterized by a large number of ships entering the port during the winter season due to the seasonality of rapidly increasing demand for heating. In winter, there is a shortage of dolphin jetty wharf (dolphins), which increases the waiting [...] Read more.
The LNG terminals are characterized by a large number of ships entering the port during the winter season due to the seasonality of rapidly increasing demand for heating. In winter, there is a shortage of dolphin jetty wharf (dolphins), which increases the waiting rate for ships. Therefore, there is a practical argument that dolphins should be additionally built to solve the ship standby problem. This study proposes the proper LNG handling capacity of a terminal with multiple dolphins of different size. Studies on calculating the LNG handling capacity of LNG terminal dolphins have been proposed by UNCTAD and Ministry of Transport of China (MTC). The formula-based calculation of LNG handling capacity has the advantage of being simple, but it has the disadvantage of not reflecting the actual operation. In this study, the proper LNG handling capacity is measured using a simulation method to overcome the limitations of formula-based calculation for Incheon port in South Korea. In order to check whether the method by simulation is justified, it is compared with the unloading capacity by the calculation formula. This study finds that the proper (or optimal) LNG handling capacity of Incheon port is determined by a dolphin occupancy of 49%, where the dolphin’s profits are maximized. As the results of simulation model, the proper (or optimal) loading capacity is 38.5 million m3 when dolphin occupancy is 49%. The capacity of individual dolphin is estimated at 17.0 million m3 for 70,000 DWT dolphin and 21.2 million m3 for 120,000 DWT dolphin, respectively. The main points of this study to use simulation model are as follows: First, the number of non-working days should be considered. Second, the optimal dolphin occupancy should be determined by finding the maximum profit point of using the pier. Third, if the size of the dolphin is different, an appropriate simulation will be implemented. Fourth, the data of the peak season should be analyzed. Finally, it should be checked whether the ship waiting rate is acceptable level or not. Full article
(This article belongs to the Special Issue Advances in Maritime Economics and Logistics)
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29 pages, 12520 KiB  
Article
On the Development of a Mid-Depth Lagrangian Float for Littoral Deployment
by Yuri Katz and Morel Groper
J. Mar. Sci. Eng. 2022, 10(12), 2030; https://doi.org/10.3390/jmse10122030 - 19 Dec 2022
Viewed by 1587
Abstract
This study presents the complete, detailed development process of an enhanced one-man portable Lagrangian float designed for littoral deployment to depths of up to 300 m. The design focused on maximization of the Lagrangian characteristics of the hull, minimization of the noise emission [...] Read more.
This study presents the complete, detailed development process of an enhanced one-man portable Lagrangian float designed for littoral deployment to depths of up to 300 m. The design focused on maximization of the Lagrangian characteristics of the hull, minimization of the noise emission and energy efficiency of the propulsion system, and the versatility of the platform for various scientific missions. The platform is propelled by a variable buoyancy engine that is actuated by an oil-submerged, gas-pressure assisted micro gear pump. The pressure assistance lowers the pressure differential across the pump ports at depth, resulting in quieter and more efficient operation. An enhanced proportional–integral–differential control scheme is employed to pilot the platform. To enhance diving safety, a software safety agent was incorporated. If the software safety agent detects a major failure, a drop weight is released. To eliminate the chance of water ingress through dynamic hull penetration, the drop weight is actuated by an in-house developed magnetic coupling mechanism. An onboard installed hydrophone continuously records and monitors ambient sounds for phenomena of interest and enables commands and mission updates from the surface. For surface recovery, the platform is equipped with GPS and an Iridium beacon for long-range localization, and an RF beacon and strobe for short-range localization and as a backup. The performance of the platform is demonstrated in a simulation and in an actual real sea mission conducted in the eastern Mediterranean at a depth of 10 and 12 m. Full article
(This article belongs to the Section Ocean Engineering)
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11 pages, 863 KiB  
Article
Analytical Description of an Axisymmetric Supercavitation Bubble in a Viscous Flow
by Lotan Arad Ludar and Alon Gany
J. Mar. Sci. Eng. 2022, 10(12), 2029; https://doi.org/10.3390/jmse10122029 - 19 Dec 2022
Cited by 1 | Viewed by 1287
Abstract
One of the basic elements which characterizes flow regimes, is viscosity. This element has typically been neglected in research on supercavitational flows, describing and predicting supercavitation bubbles geometry and formation using non-viscous potential flows. Arguing that the viscosity effect is much smaller than [...] Read more.
One of the basic elements which characterizes flow regimes, is viscosity. This element has typically been neglected in research on supercavitational flows, describing and predicting supercavitation bubbles geometry and formation using non-viscous potential flows. Arguing that the viscosity effect is much smaller than the inertial effect at high flow speeds, the viscosity has been ignored and the only parameter for modeling the flow has been the cavitation number. However, for some situations and conditions, the viscosity was found to be significant and crucial for the bubble geometry and formation, especially at the supercavitation bubble detachment point, hence some investigations based on numerical calculations have taken viscosity into account. This paper presents an analytical model of an axisymmetric supercavitation bubble in a viscous flow according to Serebryakov annular model for calculation of axisymmetric cavity flows. Viscosity effect on the bubble geometry is suggested, and an analysis for validation and examination is presented as well. The results show the change of the bubble formation from past models due to the viscosity, and offer a more accurate description of the bubble geometry close to the detachment point. Moreover, the slenderness parameter is calculated and presented for supercavitation bubbles in a viscous flow together with its dependency on Reynolds number and the cavitation number. The analysis reveals that the slenderness parameter increases with increasing both the cavitation number and Reynolds number, where the latter has a substantial effect. Full article
(This article belongs to the Special Issue Verification and Validation Analysis on Marine Applications)
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15 pages, 950 KiB  
Article
Daily Rhythmicity of Hepatic Rhythm, Lipid Metabolism and Immune Gene Expression of Mackerel Tuna (Euthynnus affinis) under Different Weather
by Wenwen Wang, Jing Hu, Zhengyi Fu, Gang Yu and Zhenhua Ma
J. Mar. Sci. Eng. 2022, 10(12), 2028; https://doi.org/10.3390/jmse10122028 - 19 Dec 2022
Cited by 2 | Viewed by 1898
Abstract
In order to investigate the rhythmic changes in gene expression in the liver of mackerel tuna (Euthynnus affinis) under sunny and cloudy conditions, this experiment had four sampling times (6:00, 12:00, 18:00 and 24:00) set on sunny and cloudy days to [...] Read more.
In order to investigate the rhythmic changes in gene expression in the liver of mackerel tuna (Euthynnus affinis) under sunny and cloudy conditions, this experiment had four sampling times (6:00, 12:00, 18:00 and 24:00) set on sunny and cloudy days to determine the expression of their immune, metabolic and rhythmic genes. The results showed that daily rhythmicity was present within most of the rhythm genes (CREB1, CLOCK, PER1, PER2, PER3, REVERBA, CRY2 and BMAL1), metabolic genes (SIRT1 and SREBP1) and immune genes (NF-kB1, MHC-I, ALT, IFNA3, ISY1, ARHGEF13, GCLM and GCLC) in this study under the sunny and cloudy condition (p < 0.05). The expression levels of CREB1, PER1, PER3, RORA, REVERBA, CRY1 and BMAL1 within rhythm genes were significantly different (p < 0.05) in the same time point comparison between sunny and cloudy conditions at 6:00, 12:00, 18:00 and 24:00; metabolic genes had the expression levels of LPL at 6:00, 12:00, 18:00 and 24:00 in the same time point comparison (p < 0.05); immune genes only had significant differences in the expression levels of IFNA3 at 6:00, 12:00, 18:00 and 24:00 (p < 0.05). This study has shown that rhythm, lipid metabolism and immune genes in the livers of mackerel tuna are affected by time and weather and show significant changes in expression. Full article
(This article belongs to the Special Issue New Techniques in Marine Aquaculture)
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3 pages, 189 KiB  
Editorial
Geological Oceanography: Towards a Conceptual Framework
by George Kontakiotis, Assimina Antonarakou and Dmitry A. Ruban
J. Mar. Sci. Eng. 2022, 10(12), 2027; https://doi.org/10.3390/jmse10122027 - 19 Dec 2022
Viewed by 1326
Abstract
Research into modern oceans, seas, and their coastal zones, as well as marine ecosystems, provides valuable information for deciphering the geological dynamics [...] Full article
(This article belongs to the Special Issue Recent Advances in Geological Oceanography)
15 pages, 3028 KiB  
Article
Double Broad Reinforcement Learning Based on Hindsight Experience Replay for Collision Avoidance of Unmanned Surface Vehicles
by Jiabao Yu, Jiawei Chen, Ying Chen, Zhiguo Zhou and Junwei Duan
J. Mar. Sci. Eng. 2022, 10(12), 2026; https://doi.org/10.3390/jmse10122026 - 18 Dec 2022
Cited by 1 | Viewed by 1834
Abstract
Although broad reinforcement learning (BRL) provides a more intelligent autonomous decision-making method for the collision avoidance problem of unmanned surface vehicles (USVs), the algorithm still has the problem of over-estimation and has difficulty converging quickly due to the sparse reward problem in a [...] Read more.
Although broad reinforcement learning (BRL) provides a more intelligent autonomous decision-making method for the collision avoidance problem of unmanned surface vehicles (USVs), the algorithm still has the problem of over-estimation and has difficulty converging quickly due to the sparse reward problem in a large area of sea. To overcome the dilemma, we propose a double broad reinforcement learning based on hindsight experience replay (DBRL-HER) for the collision avoidance system of USVs to improve the efficiency and accuracy of decision-making. The algorithm decouples the two steps of target action selection and target Q value calculation to form the double broad reinforcement learning method and then adopts hindsight experience replay to allow the agent to learn from the experience of failure in order to greatly improve the sample utilization efficiency. Through training in a grid environment, the collision avoidance success rate of the proposed algorithm was found to be 31.9 percentage points higher than that in the deep Q network (DQN) and 24.4 percentage points higher than that in BRL. A Unity 3D simulation platform with high fidelity was also designed to simulate the movement of USVs. An experiment on the platform fully verified the effectiveness of the proposed algorithm. Full article
(This article belongs to the Special Issue Ship Collision Risk Assessment)
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25 pages, 6765 KiB  
Article
Real-Time Emergency Collision Avoidance for Unmanned Surface Vehicles with COLREGS Flexibly Obeyed
by Yang Qu and Lilong Cai
J. Mar. Sci. Eng. 2022, 10(12), 2025; https://doi.org/10.3390/jmse10122025 - 18 Dec 2022
Cited by 2 | Viewed by 1535
Abstract
This paper presents a real-time emergency collision-avoidance method for unmanned surface vehicles (USVs) with the International Regulations for Preventing Collisions at Sea (COLREGS) flexibly obeyed. The pivotal issue is that some traffic vessels may violate the demands of this convention, which would increase [...] Read more.
This paper presents a real-time emergency collision-avoidance method for unmanned surface vehicles (USVs) with the International Regulations for Preventing Collisions at Sea (COLREGS) flexibly obeyed. The pivotal issue is that some traffic vessels may violate the demands of this convention, which would increase the risk of collision if the USV blindly obeys the COLREGS rules. To avoid mandatory compliance with these COLREGS rules, a real-time truncated velocity obstacle (TVO) algorithm is proposed to assign a collision-free velocity vector for the control system to realize. Considering a reasonable trade-off between safety and the COLREGS rules, the proposed collision-avoidance method expands the TVO’s area based on the velocity uncertainties of traffic vessels, which greatly enhance the safety of collision-avoidance operations and encourage the USV to follow the COLREGS rules. To promptly realize an assigned collision-free velocity, this paper also develops a discrete simultaneous planning and executing (SPAE) controller design. The proposed discrete controller is divided into three parts: online polynomial planning to satisfy the constraints of tracking errors, an accurate uncertainty estimation, and an algebraic control law to promptly execute the planned polynomial. Numerical results have validated the reliability and intelligibility of the proposed collision-avoidance method. Furthermore, simulated and experimental results have validated the effectiveness of the proposed controller design. Full article
(This article belongs to the Special Issue Advances in Marine Vehicles, Automation and Robotics)
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24 pages, 4172 KiB  
Review
Advances in the Technologies for Marine Salinity Measurement
by Lijuan Gu, Xiangge He, Min Zhang and Hailong Lu
J. Mar. Sci. Eng. 2022, 10(12), 2024; https://doi.org/10.3390/jmse10122024 - 18 Dec 2022
Cited by 9 | Viewed by 2573
Abstract
As one of the most important physical parameters of seawater, salinity is essential to study climatological change, to trace seawater masses and to model ocean dynamics. The traditional way to conduct salinity measurement in hydrographical observation is to use a standard conductivity-temperature-depth (CTD) [...] Read more.
As one of the most important physical parameters of seawater, salinity is essential to study climatological change, to trace seawater masses and to model ocean dynamics. The traditional way to conduct salinity measurement in hydrographical observation is to use a standard conductivity-temperature-depth (CTD) probe where the salinity determination is based on a measurement of electrical conductivity. This article describes some developments of recent years that could lead to a new generation of instruments for the determination of salinity in seawater. Salinity determination with optical salinity sensor based on the refractive index measurement have been extensively studied. Different ways to conduct refractive index measurements are summarized, including measurements based on beam deviation, light wave mode coupling and swelling of surface coating material, among which the optical fiber sensors are promising candidates for further commercialization. Complementary to the above-mentioned direct measurement salinity point sensors, seismic observation takes advantages of large scale multichannel seismic data to retrieve the ocean salinity with high lateral resolution of ∼10 m. This work provide comprehensive information in the techniques related to the marine salinity measurement. Full article
(This article belongs to the Section Physical Oceanography)
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26 pages, 7256 KiB  
Article
Dynamic Analysis and Extreme Response Evaluation of Lifting Operation of the Offshore Wind Turbine Jacket Foundation Using a Floating Crane Vessel
by Mingsheng Chen, Guibo Yuan, Chun Bao Li, Xianxiong Zhang and Lin Li
J. Mar. Sci. Eng. 2022, 10(12), 2023; https://doi.org/10.3390/jmse10122023 - 18 Dec 2022
Cited by 12 | Viewed by 2466
Abstract
The jacket is the most widely-used fixed foundation for offshore wind turbines due to its superior strength and low installation cost in relatively deep waters. Floating crane vessels are commonly used to install jacket foundations. However, the dynamic coupling between the jacket and [...] Read more.
The jacket is the most widely-used fixed foundation for offshore wind turbines due to its superior strength and low installation cost in relatively deep waters. Floating crane vessels are commonly used to install jacket foundations. However, the dynamic coupling between the jacket and the floating vessel might generate complex dynamic responses under wave action. The complexity of the multi-body system requires comprehensive time-domain simulations and statistical analysis to obtain reliable results, especially for the evaluation of the operational safety of offshore lift installations of a jacket foundation. In this context, this study performs numerical simulations and statistical analyses to predict the extreme responses and the preliminary allowable sea states for guiding the lowering operation of a jacket using a floating crane vessel. First, ANSYS-AQWA is used to obtain the hydrodynamic coefficients of the vessel in the frequency domain. A nonstationary time-domain simulation of jacket lowering with winches is performed to identify several preliminary critical vertical positions of the jacket from the time series in an irregular wave. The extreme responses of a target probability are evaluated by the extreme distribution model after a large number of steady-state time-domain simulations of the critical vertical positions in irregular waves. The most critical vertical position is determined from three preliminary critical vertical positions by comparing the extreme responses. Eigenvalue analysis and spectrum analysis of the most critical vertical position of the jacket are carried out to find the natural periods of the system and the dynamic coupling characteristics between different components. The influence of wave direction, significant wave height, and spectrum peak period on the dynamic responses are also analyzed in the most critical vertical position. Furthermore, the optimal wave direction is determined as the head sea. Preliminary allowable sea states are derived by comparing the calculated dynamic amplification coefficient with the defined operational criteria. Full article
(This article belongs to the Topic Wind, Wave and Tidal Energy Technologies in China)
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25 pages, 15796 KiB  
Article
A Hybrid Model Based on the Bifurcation Approach for Internal Turbulent Flow with Rotation and Streamline Curvature Effects
by Kaiwen Pang, Xianbei Huang, Zhuqing Liu, Yaojun Li and Wei Yang
J. Mar. Sci. Eng. 2022, 10(12), 2022; https://doi.org/10.3390/jmse10122022 - 18 Dec 2022
Cited by 1 | Viewed by 1278
Abstract
Abstract: This study aims to research the prediction performance of a bifurcated adaptive DDES (BADDES) model in different turbulent flows with rotation and curvature [...] Full article
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20 pages, 7461 KiB  
Review
Ocean Fronts and Their Acoustic Effects: A Review
by Yuyao Liu, Zhou Meng, Wen Chen, Yan Liang, Wei Chen and Yu Chen
J. Mar. Sci. Eng. 2022, 10(12), 2021; https://doi.org/10.3390/jmse10122021 - 17 Dec 2022
Cited by 2 | Viewed by 1680
Abstract
As one of the widespread physical phenomena in the global ocean system, the ocean front has a very important influence on underwater sound propagation. Firstly, this paper systematically reviews several methods for the detection of ocean fronts in the past decades, including traditional [...] Read more.
As one of the widespread physical phenomena in the global ocean system, the ocean front has a very important influence on underwater sound propagation. Firstly, this paper systematically reviews several methods for the detection of ocean fronts in the past decades, including traditional oceanographic methods, artificial intelligence methods, and acoustic methods, highlighting the advantages and disadvantages of each method. Next, some modeling studies of ocean fronts are reported in this paper. Based on the above research, we pay more attention to research progress on the acoustic effects of ocean fronts, including simulation analysis and experimental research, which has also been the focus of underwater acousticians for a long time. In addition, this paper looks forward to the future development direction of this field, which can provide good guidance for the study of ocean fronts and their acoustic effects in the future. Full article
(This article belongs to the Section Physical Oceanography)
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14 pages, 2691 KiB  
Article
Development and Influence of Pore Pressure around a Bucket Foundation in Silty Soil
by Xue-Liang Zhao, Xin Wang, Peng-Cheng Ding, Shu-Huan Sui and Wen-Ni Deng
J. Mar. Sci. Eng. 2022, 10(12), 2020; https://doi.org/10.3390/jmse10122020 - 17 Dec 2022
Cited by 4 | Viewed by 1339
Abstract
Silty soil is common in the seabed of eastern coastal areas of China. The behaviors of the silty soil and a bucket foundation installed within it need more study. In this work, model tests of a bucket foundation in silty soil were performed. [...] Read more.
Silty soil is common in the seabed of eastern coastal areas of China. The behaviors of the silty soil and a bucket foundation installed within it need more study. In this work, model tests of a bucket foundation in silty soil were performed. The development of the excess pore water pressures in the different positions around the bucket was measured. Different loading conditions, with a change in the horizontal cyclic load amplitude ratio, horizontal cyclic frequency, and vertical load ratio, were considered. The effects of the pore water pressure on the shear strength of the soil around the bucket and the horizontal bearing capacity of the bucket foundation were investigated. The results show that the normalized pore water pressures close to the bucket wall at depths between 0.1 L and 0.3 L exhibit distinct change under the cyclic load. Consistent with the distribution of the pore water pressure, the degradation of the undrained shear strength is more obvious with a greater load amplitude ratio, a greater load frequency, and a smaller vertical load. The degradation rate of the static horizontal ultimate bearing capacity is in a range of 1.57% to 14.90%, under different loading conditions. Full article
(This article belongs to the Special Issue New Challenges in Offshore Geotechnical Engineering Developments)
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14 pages, 5919 KiB  
Article
Numerical Investigations on Scour and Flow around Two Crossing Pipelines on a Sandy Seabed
by Fan Zhang, Zhipeng Zang, Ming Zhao, Jinfeng Zhang, Botao Xie and Xing Zou
J. Mar. Sci. Eng. 2022, 10(12), 2019; https://doi.org/10.3390/jmse10122019 - 17 Dec 2022
Cited by 2 | Viewed by 1481
Abstract
When a pipeline is laid on the seabed, local scour often occurs below it due to sea currents. In practical engineering, there are some cases that two pipelines laid on the seabed need to cross with each other. The complex flow structures around [...] Read more.
When a pipeline is laid on the seabed, local scour often occurs below it due to sea currents. In practical engineering, there are some cases that two pipelines laid on the seabed need to cross with each other. The complex flow structures around two crossing pipelines make the scour characteristics different from that of an isolated single pipeline. In this study, scour below two crossing pipelines was simulated numerically using the CFD software Flow-3D. The study is focused on the effect of the intersecting angle on the equilibrium depth and time scale of scour below the crossing position. Five intersecting angles, i.e., α = 0°, 15°, 30°, 45° and 90°, are considered, where α = 0° and 90° represent two pipelines parallel and perpendicular to each other, respectively. The results show that the equilibrium depth and the time scale of scour below the two crossing pipelines are greater than those of an isolated single pipeline. The equilibrium depth and time scale of scour have the largest values at α = 0° and decrease with the increase of the intersecting angle. Finally, the flow structures around the crossing pipelines are presented to explain the scour process. Full article
(This article belongs to the Special Issue CFD Analysis in Ocean Engineering)
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22 pages, 1770 KiB  
Article
Autonomous Underwater Vehicle Path Planning Method of Soft Actor–Critic Based on Game Training
by Zhuo Wang, Hao Lu, Hongde Qin and Yancheng Sui
J. Mar. Sci. Eng. 2022, 10(12), 2018; https://doi.org/10.3390/jmse10122018 - 16 Dec 2022
Cited by 4 | Viewed by 1706
Abstract
This study aims to solve the issue of the safe navigation of autonomous underwater vehicles (AUVs) in an unknown underwater environment. AUV will encounter canyons, rocks, reefs, fish, and underwater vehicles that threaten its safety during underwater navigation. A game-based soft actor–critic (GSAC) [...] Read more.
This study aims to solve the issue of the safe navigation of autonomous underwater vehicles (AUVs) in an unknown underwater environment. AUV will encounter canyons, rocks, reefs, fish, and underwater vehicles that threaten its safety during underwater navigation. A game-based soft actor–critic (GSAC) path planning method is proposed in this study to improve the adaptive capability of autonomous planning and the reliability of obstacle avoidance in the unknown underwater environment. Considering the influence of the simulation environment, the obstacles in the simulation environment are regarded as agents and play a zero-sum game with the AUV. The zero-sum game problem is solved by improving the strategy of AUV and obstacles, so that the simulation environment evolves intelligently with the AUV path planning strategy. The proposed method increases the complexity and diversity of the simulation environment, enables AUV to train in a variable environment specific to its strategy, and improves the adaptability and convergence speed of AUV in unknown underwater environments. Finally, the Python language is applied to write an unknown underwater simulation environment for the AUV simulation testing. GSAC can guide the AUV to the target point in the unknown underwater environment while avoiding large and small static obstacles, canyons, and small dynamic obstacles. Compared with the soft actor–critic(SAC) and the deep Q-network (DQN) algorithm, GSAC has better adaptability and convergence speed in the unknown underwater environment. The experiments verifies that GSAC has faster convergence, better stability, and robustness in unknown underwater environments. Full article
(This article belongs to the Special Issue AI for Navigation and Path Planning of Marine Vehicles)
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21 pages, 2524 KiB  
Article
Preliminary Analysis on the Hydrostatic Stability of a Self-Aligning Floating Offshore Wind Turbine
by Diane Scicluna, Claire De Marco Muscat-Fenech, Tonio Sant, Giuliano Vernengo and Tahsin Tezdogan
J. Mar. Sci. Eng. 2022, 10(12), 2017; https://doi.org/10.3390/jmse10122017 - 16 Dec 2022
Cited by 1 | Viewed by 1997
Abstract
There exist vast areas of offshore wind resources with water depths greater than 100 m that require floating structures. This paper provides a detailed analysis on the hydrostatic stability characteristics of a novel floating wind turbine concept. The preliminary design supports an 8 [...] Read more.
There exist vast areas of offshore wind resources with water depths greater than 100 m that require floating structures. This paper provides a detailed analysis on the hydrostatic stability characteristics of a novel floating wind turbine concept. The preliminary design supports an 8 MW horizontal-axis wind turbine with a custom self-aligning single-point mooring (SPM) floater, which is to be constructed within the existing shipyard facilities in the Maltese Islands, located in the Central Mediterranean Sea. The theoretical hydrostatic stability calculations used to find the parameters to create the model are validated using SESAM®. The hydrostatic stability analysis is carried out for different ballast capacities whilst also considering the maximum axial thrust induced by the rotor during operation. The results show that the entire floating structure exhibits hydrostatic stability characteristics for both the heeling and pitching axes that comply with the requirements set by the DNV ST-0119 standard. Numerical simulations using partial ballast are also presented. Full article
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16 pages, 3640 KiB  
Article
Collision Risk Index Calculation Based on an Improved Ship Domain Model
by Weifeng Li, Lufeng Zhong, Yang Xu and Guoyou Shi
J. Mar. Sci. Eng. 2022, 10(12), 2016; https://doi.org/10.3390/jmse10122016 - 16 Dec 2022
Cited by 8 | Viewed by 4072
Abstract
The traditional ship collision risk index model based on the distance at the closest point of approach (DCPA) and the time to the closest point of approach (TCPA) is insufficient for estimating ship collision risk and planning collision avoidance operations. This paper constructs [...] Read more.
The traditional ship collision risk index model based on the distance at the closest point of approach (DCPA) and the time to the closest point of approach (TCPA) is insufficient for estimating ship collision risk and planning collision avoidance operations. This paper constructs an elliptical, dynamic ship domain that changes with ship speed and maneuverability parameters to overcome subjective human factors. Based on the constructed domain model, the concept of the ship domain proximity factor is introduced to improve the ship collision risk model based on DCPA and TCPA, and a risk calculation function model that considers the safety of ship navigation is constructed. The numerical calculation of the improved collision risk index calculation model confirms that the enhanced model has a higher rate of identification of risk between ships. The model is more compatible with the requirements of ship navigation decision-making and can provide theoretical support and a technical basis for research on ship collision avoidance decision-making. Full article
(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)
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21 pages, 2090 KiB  
Article
Deep Water PAH Cycling in the Japan Basin (the Sea of Japan)
by Yuliya Koudryashova, Tatiana Chizhova, Mutsuo Inoue, Kazuichi Hayakawa, Seiya Nagao, Evgeniya Marina and Rodrigo Mundo
J. Mar. Sci. Eng. 2022, 10(12), 2015; https://doi.org/10.3390/jmse10122015 - 16 Dec 2022
Cited by 2 | Viewed by 1489
Abstract
A vertical pattern of fractionated polycyclic aromatic hydrocarbons (PAH) was studied in the Japan Basin in the Sea of Japan. The highest PAH concentration was found in the mesopelagic realm, possibly resulting from deep convection and/or subduction of intermediate water and its biogeochemical [...] Read more.
A vertical pattern of fractionated polycyclic aromatic hydrocarbons (PAH) was studied in the Japan Basin in the Sea of Japan. The highest PAH concentration was found in the mesopelagic realm, possibly resulting from deep convection and/or subduction of intermediate water and its biogeochemical setting in the western Japan Basin. Using 226Ra and 228Ra as tracers revealed the PAH load in the open sea from the coastal polluted water. Dissolved PAHs (DPAH, fraction < 0.5 µm) were significantly prevalent particulate PAHs (PPAH, fraction > 0.5 µm) at all depths, associated with a predominance of dissolved organic carbon (DOC) over particulate organic carbon (POC). Hydrophobicity was more important for higher-molecular-weight PAHs to be distributed between particles and the solution, while the high Koc of low-molecular-weight PAHs indicated that their partitioning was driven by other factors, such as adsorbing of soot particles. PPAH and DPAH profiles differed from the POC and DOC profiles; nevertheless, a positive moderate correlation was found for DPAH and DOC for depths below the epipelagic, suggesting the similarity of the mechanisms of input of dissolved organic matter and DPAH into the deep interior of the Sea of Japan. The PAH flux calculations showed that biological pumps and overturning circulation contribute almost equally to removing PAHs from the bathypelagic waters of the Japan Basin. Full article
(This article belongs to the Section Marine Pollution)
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38 pages, 13954 KiB  
Article
Submarine Manoeuvrability Design: Traditional Cross-Plane vs. x-Plane Configurations in Intact and Degraded Conditions
by Benedetto Piaggio, Giuliano Vernengo, Marco Ferrando, Giorgio Mazzarello and Michele Viviani
J. Mar. Sci. Eng. 2022, 10(12), 2014; https://doi.org/10.3390/jmse10122014 - 16 Dec 2022
Cited by 1 | Viewed by 3777
Abstract
Submarines’ manoeuvrability both in intact and degraded operating conditions is the main design concern starting at the very early stages of design. This increased complexity of the design process compared to a surface vehicle can only be handled by using dynamics numerical simulations [...] Read more.
Submarines’ manoeuvrability both in intact and degraded operating conditions is the main design concern starting at the very early stages of design. This increased complexity of the design process compared to a surface vehicle can only be handled by using dynamics numerical simulations on both the vertical and horizontal manoeuvring planes. To this aim, a 6-DoF method is presented, validated, and applied to study the manoeuvring characteristics of several vessels. The analysis has been conducted considering two standpoints, i.e., to verify the design handling capabilities of the vehicles at low and high speeds and to study the off-design residual abilities in the eventual case of emergency operations with jammed/lost-control surfaces. The influence of different design features, such as, e.g., the stern plane “+” and “x” configurations, fairway size and positioning, hull dimensional ratios and restoring capabilities have been analysed in terms of impact on turning ability, course and depth changing abilities, and vertical/horizontal course stability, including the vertical damping ratio and critical velocity. Full article
(This article belongs to the Section Ocean Engineering)
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18 pages, 6447 KiB  
Article
Ships’ Small Target Detection Based on the CBAM-YOLOX Algorithm
by Yuchao Wang, Jingdong Li, Zeming Chen and Chenglong Wang
J. Mar. Sci. Eng. 2022, 10(12), 2013; https://doi.org/10.3390/jmse10122013 - 16 Dec 2022
Cited by 5 | Viewed by 1678
Abstract
In order to solve the problem of low accuracy of small target detection in traditional target detection algorithms, the YOLOX algorithm combined with Convolutional Block Attention Module (CBAM) is proposed. The algorithm first uses CBAM on the shallow feature map to better focus [...] Read more.
In order to solve the problem of low accuracy of small target detection in traditional target detection algorithms, the YOLOX algorithm combined with Convolutional Block Attention Module (CBAM) is proposed. The algorithm first uses CBAM on the shallow feature map to better focus on small target information, and the Focal loss function is used to regress the confidence of the target to overcome the positive and negative sample imbalance problem of the one-stage target detection algorithm. Finally, the Soft Non-Maximum Suppression (SNMS) algorithm is used for post-processing to solve the problem of missed detection in close range ship target detection. The experimental results show that the average accuracy of the proposed CBAM-YOLOX network target detection is improved by 4.01% and the recall rate is improved by 8.81% compared with the traditional YOLOX network, which verifies the effectiveness of the proposed algorithm. Full article
(This article belongs to the Section Ocean Engineering)
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26 pages, 8557 KiB  
Article
Semantic Recognition of Ship Motion Patterns Entering and Leaving Port Based on Topic Model
by Gaocai Li, Mingzheng Liu, Xinyu Zhang, Chengbo Wang, Kee-hung Lai and Weihuachao Qian
J. Mar. Sci. Eng. 2022, 10(12), 2012; https://doi.org/10.3390/jmse10122012 - 16 Dec 2022
Cited by 5 | Viewed by 1497
Abstract
Recognition and understanding of ship motion patterns have excellent application value for ship navigation and maritime supervision, i.e., route planning and maritime risk assessment. This paper proposes a semantic recognition method for ship motion patterns entering and leavingport based on a probabilistic topic [...] Read more.
Recognition and understanding of ship motion patterns have excellent application value for ship navigation and maritime supervision, i.e., route planning and maritime risk assessment. This paper proposes a semantic recognition method for ship motion patterns entering and leavingport based on a probabilistic topic model. The method enables the discovery of ship motion patterns from a large amount of trajectory data in an unsupervised manner and makes the results more interpretable. The method includes three modules: trajectory preprocessing, semantic process, and knowledge discovery. Firstly, based on the activity types and characteristics of ships in the harbor waters, we propose a multi-criteria ship motion state recognition and voyage division algorithm (McSMSRVD), and ship trajectory is divided into three sub-trajectories: hoteling, maneuvering, and normal-speed sailing. Secondly, considering the influence of port traffic rules on ship motion, the semantic transformation and enrichment of port traffic rules and ship location, course, and speed are combined to construct the trajectory text document. Ship motion patterns hidden in the trajectory document set are recognized using the Latent Dirichlet allocation (LDA) topic model. Meanwhile, topic coherence and topic correlation metrics are introduced to optimize the number of topics. Thirdly, a visualization platform based on ArcGIS and Electronic Navigational Charts (ENCs) is designed to analyze the knowledge of ship motion patterns. Finally, the Tianjin port in northern China is used as the experimental object, and the results show that the method is able to identify 17 representative inbound and outbound motion patterns from AIS data and discover the ship motion details in each pattern. Full article
(This article belongs to the Section Ocean Engineering)
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23 pages, 4137 KiB  
Article
Decentralized Documentation of Maritime Traffic Incidents to Support Conflict Resolution
by Dennis Jankowski, Julius Möller, Hilko Wiards and Axel Hahn
J. Mar. Sci. Eng. 2022, 10(12), 2011; https://doi.org/10.3390/jmse10122011 - 16 Dec 2022
Viewed by 1150
Abstract
For the investigation of major traffic accidents, larger vessels are obliged to install a voyage data recorder (VDR). However, not every vessel is equipped with a VDR, and the readout is often a manual process that is costly. In addition, not only ship-related [...] Read more.
For the investigation of major traffic accidents, larger vessels are obliged to install a voyage data recorder (VDR). However, not every vessel is equipped with a VDR, and the readout is often a manual process that is costly. In addition, not only ship-related information can be relevant for reconstructing traffic accidents, but also information from other entities such as meteorological services or port operators. Moreover, another major challenge is that entities tend to trust only their records, and not those of others as these could be manipulated in favor of the particular recording entity (e.g., to disguise any damage caused). This paper presents an approach to documenting arbitrary data from different entities in a trustworthy, decentralized, and tamper-proof manner to support the conflict resolution process. For this purpose, all involved entities in a traffic situation can contribute to the documentation by persisting their available data. Since maritime stakeholders are equipped with various sensors, a diverse and meaningful data foundation can be aggregated. The data is then signed by a mutually agreed upon timestamping authority (TSA). In this way, everyone can cryptographically verify whether the data has been subsequently changed. This approach was successfully applied in practice by documenting a vessel’s mooring maneuver. Full article
(This article belongs to the Special Issue Maritime Security and Risk Assessments)
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21 pages, 10223 KiB  
Article
Discrete Element Simulation on Macro-Meso Mechanical Characteristics of Natural Gas Hydrate-Bearing Sediments under Shearing
by Meng Li, Hengjie Luan, Yujing Jiang, Sunhao Zhang, Qinglin Shan, Wei Liang and Xianzhuang Ma
J. Mar. Sci. Eng. 2022, 10(12), 2010; https://doi.org/10.3390/jmse10122010 - 16 Dec 2022
Viewed by 1243
Abstract
In order to study the macro-meso shear mechanical characteristics of natural gas hydrate-bearing sediments, the direct shear simulations of natural gas hydrate-bearing sediment specimens with different saturations under different normal stress boundary conditions were carried out using the discrete element simulation program of [...] Read more.
In order to study the macro-meso shear mechanical characteristics of natural gas hydrate-bearing sediments, the direct shear simulations of natural gas hydrate-bearing sediment specimens with different saturations under different normal stress boundary conditions were carried out using the discrete element simulation program of particle flow, and the macro-meso shear mechanical characteristics of the specimens and their evolution laws were obtained, and their shear damage mechanisms were revealed. The results show that the peak intensity of natural gas hydrate-bearing sediments increases with the increase in normal stress and hydrate saturation. Hydrate particles and sand particles jointly participate in the formation and evolution of the force chain, and sand particles account for the majority of the force chain particles and take the main shear resistance role. The number of cracks produced by shear increases with hydrate saturation and normal stress. The average porosity in the shear zone shows an evolutionary pattern of decreasing and then increasing during the shear process. Full article
(This article belongs to the Special Issue Gas Hydrate—Unconventional Geological Energy Development)
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19 pages, 2033 KiB  
Article
A Critical Examination for Widespread Usage of Shipping Big Data Analytics in China
by Jinhai Chen, Siheng Chang, Pengfei Zhang, Qiong Chen, Peng Peng and Christophe Claramunt
J. Mar. Sci. Eng. 2022, 10(12), 2009; https://doi.org/10.3390/jmse10122009 - 16 Dec 2022
Cited by 1 | Viewed by 2097
Abstract
Big Data Analytics (BDA) provides valuable opportunities for the optimization of maritime shipping management and operations. This might have a significant and beneficial impact on the Chinese maritime industry, which has recently emerged as a prominent player on the global stage due to [...] Read more.
Big Data Analytics (BDA) provides valuable opportunities for the optimization of maritime shipping management and operations. This might have a significant and beneficial impact on the Chinese maritime industry, which has recently emerged as a prominent player on the global stage due to the fast development of its maritime infrastructures and economical opportunities. This paper introduces two-field research conducted by a web-based questionnaire survey and semi-structured interviews with a large number of stakeholders in the maritime sector. The analyses show the impact of the development of big data technologies as well as current obstacles which constrain their deployment in the global maritime sector. The paper finally suggests several directions for promoting the wide-scale utilization of BDA in the maritime industry. Full article
(This article belongs to the Section Ocean Engineering)
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14 pages, 4491 KiB  
Article
Identifying Submarine Engineering Geologic Hazards in a Potential Gas Hydrate Target Area on the Southern Continental Margin of the South China Sea
by Zhenqiang Xu, Yang Li, Wei Yan, Yaoyao Lv, Guoqing Zhang, Dongyu Lu and Zuofei Zhu
J. Mar. Sci. Eng. 2022, 10(12), 2008; https://doi.org/10.3390/jmse10122008 - 16 Dec 2022
Viewed by 1343
Abstract
The southern continental margin-slope area of the South China Sea is a complex passive continental margin with diverse tectonic structures and movements. This area is rich in gas hydrate resources and is also an area with a high incidence of potential geological hazards. [...] Read more.
The southern continental margin-slope area of the South China Sea is a complex passive continental margin with diverse tectonic structures and movements. This area is rich in gas hydrate resources and is also an area with a high incidence of potential geological hazards. Identifying and understanding the potential submarine geological hazards in this area is very important for disaster prevention and management during the future exploration and development of marine resources. In this paper, five types of potentially hazardous geological bodies are identified in the research area through high-precision two-dimensional seismic processing and interpretation, including submarine mounds, pockmarks, mass transport deposits, submarine collapses and faults. At the same time, the seismic reflection characteristics and the changes in its morphology and surrounding strata are described. In addition to the causes of geological hazards in this region and their influence on exploration and development, the research prospects of geological hazards in this region are also suggested. Special tectonic and sedimentary conditions, fluid activities and hydrate decomposition may be the conditions for geological hazards in this region, which pose a significant threat to the exploration and development of seabed resources and marine engineering construction in this region. Not only does our conclusion provide useful data for the development and utilization of gas hydrate, but it also presents theoretical suggestions for reducing geological hazards in the development process. Full article
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