Traditional Marine Research Articles

Marine Renewable Energies and Maritime Spatial Planning: different national proposals for their legal and spatial context

In 2022, the European Commission adopted the REPower EU package which proposes to further increase the 2030 target for renewables from 40 % to 45 % and revise the Renewable Energy Directive to accelerate permitting. Moreover, the European Offshore Renewable Energy Strategy estimates to have an installed capacity of at least 60 GW of offshore wind and at least 1 GW of ocean energy by 2030, reaching 300 GW and 40 GW of installed capacity, respectively, by 2050, which would require less than 3% of the European maritime space.
 The marine environment is an ecosystem that supports a set of uses and human activities, contributing to economic and social development. Most of the uses and activities require the use of maritime space, either temporarily or permanently, increasing the potential for conflict with existing and traditional marine uses. The European Directive 2014/89/UE establishes a framework for marine spatial planning (MSP) and requires the competent authorities in each Member State to develop national maritime spatial plans, analysing and organizing human activities in marine areas, applying ecosystem-based approach, involving stakeholders, in order to achieve ecological, economic and social objectives. Moreover, this MSP framework not only intends to mitigate possible present and future spatial conflicts but also contemplates the emerging sectors and the most recent technological development in the sea. 
 In the context of the EU-funded SAFEWave project (https://www.safewave-project.eu/), the different National Maritime Spatial Plans in Europe and how the Marine Renewable Energies (MRE) have been considered or integrated in different national plans have been analysed (i.e. Spain, France, Ireland, Portugal and United Kingdom). The outcome of this analysis has identified: (i) the approaches to implementation of MSP plans vary by country and sometimes within countries; (ii) differences in the stakeholder or public involvement in MSP (ii) differences in national MRE targets; (ii) different strategies and priorities for raising the issue of MRE within the national MSP; (iii) for which countries MREs are strategics in their national plans; (iv) conflicts with other uses (i.e. Marine Protected Areas), and mechanisms to solve them; (vi) technical, socio-economic and environmental factors considered for MRE polygons identification in national MSP; (vii) the development of national MSP requires a review of the authorization or concession procedures for the allocation or reservation of areas for MREs. 
 Ultimately, comparing the integration of national plans for marine renewable energy (MRE) into national marine spatial plans (MSP) can inform and guide management strategies, legislation, and policies to support management actions and efficiently plan future MRE deployments.

A Comparative Techno-Economic Assessment of Alternative Fuels in SOFC Systems for Cruise Ships

Maritime transportation accounts for about 2.9% of global greenhouse gas (GHG) emissions, according to the fourth International Maritime Organization (IMO) GHG study. In the period from 2012 to 2018, shipping emissions have increased by almost 10%. Facing growing political and societal pressure, the IMO has established GHG emissions reduction targets consistent with the Paris Agreement temperature goals, aiming to reduce the total annual GHG emissions by at least 50% by 2050 compared to 2008 levels. In this context, alternative fuels and innovative technologies are needed to allow the maritime industry to comply with forthcoming regulations, as well as to fulfil decarbonisation targets within the European and the global markets.The shipping industry has already started to transition from traditional marine fuels, such as heavy fuel oil and marine diesel oil, to Liquified Natural Gas (LNG) in Internal Combustion Engines (ICEs). However, this can only be regarded as a bridging solution. In recent years, three major research lines can be identified: First, battery-electric propulsion, exploring the potential benefits of shaving peak thruster power and improving the energy efficiency and range of ships. Second, Solid Oxide Fuel Cells (SOFCs), which have a marked advantage of fuel flexibility and offer higher electrical efficiencies than ICEs and other fuel cell technologies, as well as higher-grade waste heat. Third, alternative marine fuels, such as synthetic hydrocarbons, biofuels, ammonia and hydrogen, as a way to significantly reduce or even phase out GHG emissions and other air pollutants.The present study bridges the aforementioned research lines by proposing a novel integrated marine energy system composed of an SOFC-battery hybrid genset that consumes LNG. The objective is to perform a techno-economic assessment of the hybrid genset for LNG and four identified potential alternative fuels (i.e. methanol, diesel, ammonia, and hydrogen). The best solutions will be identified and analysed, and a decision-making framework will be proposed. The comparison will identify the critical conditions for the genset processes being competitive to the state-of-the-art engine-based energy system.The analysis is divided into two main parts. The first part is dedicated to the SOFC module, which is composed of the SOFC stack and the balance of plant equipment. The BOP includes fuel storage, reformer, combustor, heat recovery system, pumps, and blowers. Previous work by the authors has developed the thermodynamic analysis of the genset systems that provide the starting point for the present analysis. The flow-sheet software Cycle Tempo was used in those analyses. The SOFC module has a nominal power production of 100 kWe, which is achieved by combining several stacks of 10 kWe, and produces hot water at 90 °C and saturated steam at 180 °C from waste heat recovery.In the second part, the SOFC-battery hybrid genset is achieved by combining several 100 kWe SOFC modules into power blocks and hybridizing them with batteries. The systems are designed to cover all the electricity and heat demands of the vessel, including propulsion and hotel load. A representative electrical demand of a large cruise ship is selected in the range of 30-60 MWe, of which about 80% is required for propulsion while the remaining is needed for the hotel.Among the main criteria for comparing the hybrid genset running on different fuels are the total annual cost, composed of the annual investment cost and annual operation cost, and the Levelized Costs of Energy, Electricity and Exergy. The latter is especially important because of the joint production of electricity and heat (saturated steam at 180 °C and hot water at 90 °C) that takes place in the genset. The investment cost was estimated using data collected from the literature or provided by manufacturers. The necessary replacement of SOFC stacks is taken into account, given the stack lifetime. Weight and volume requirements associated with the use of different fuels are assessed. The annual operation cost consists of fuel consumption and maintenance costs, as well as the application of an environmental tax for CO2 emissions.Different scenarios are proposed to evaluate the impacts of improvements in key parameters on the overall feasibility of the systems. The robustness of the results is evaluated by sensitivity and uncertainty analyses of the key technical and economic parameters used in the model, including, among other parameters, the fuel purchase price, SOFC and battery investment costs, stack lifetime, and interest rate. This research provides a systematic comparison of the techno-economic feasibility of five alternative fuels for cruise ships. The results will aid decision-makers, including shipyards and policymakers, in designing new energy systems with low emissions for maritime applications.

Low-frequency sound-absorbing metamaterial based on a series-parallel arrangement structure

Low-frequency noise has a long wavelength, decays very slowly, and is extremely penetrating. Traditional marine acoustic insulation materials have difficulty achieving effective control of this low-frequency noise. In this paper, a series-parallel arrangement structure of a low-frequency metamaterial is designed, which mainly comprises convoluted channels and Helmholtz cavities in series and a sandwich arrangement of multiple cells (as opposed to the traditional parallel arrangement). We use a numerical method to establish an acoustic-solid coupling model for the metamaterial, consider the influence of thermal and viscous losses on its sound absorption performance, and investigate the sound absorption characteristics and mechanisms of the single-cell and multicell structures. The metamaterial designed in this paper shows an average absorption coefficient of 0.97 in the range of 130–145 Hz. An experimental model was prepared by 3D printing, and the intended sound absorption effect was experimentally verified.

Tip clearance influence on hydrodynamic performance and pressure fluctuation of a composite ducted propeller using a two-way FSI method

With the development of advanced materials, composite materials have been studied by researchers over the world to make them more applicable to many applications, especially in the marine industry. As an important component of marine vehicles, propellers have been studied over decades to achieve the goals of increasing hydrodynamic performances and structural properties. However, traditional marine propellers manufactured with metallic materials have many limits. Therefore, the use of composite material to improve the performances of the propeller has become a research hotspot since their great structural performances and material damping properties can improve the comprehensive performance of the propellers such as increased hydrodynamic performances and reduced pressure fluctuation characteristics. The ducted propeller is a typical marine propulsor, which has a tip clearance between the blade tip and the inner face of the duct that can cause a complex fluid flow around the blades and influence the performance of the propeller. In this research, the tip clearance influence on hydrodynamic performance and pressure fluctuation of a composite ducted propeller compared with a metallic equivalent is calculated using a two-way fluid-structure interaction (FSI) method. The results indicate that the use of composite materials with a proper stacking sequence on the ducted propeller blade with a smaller tip clearance size corresponding to GSR = 0.417 can achieve good hydrodynamic properties for the propeller, and it has a significant inhibiting effect on pressure fluctuations on the blade surface.

Experimental investigation on vortex-induced vibration characteristics of a segmented free-hanging flexible riser

Different from the traditional marine riser, the vertical lifting pipeline in the deep-sea mining system can be regarded as a free-hanging flexible riser with an unconstrained bottom end. Likewise, problems in terms of vortex-induced vibration (VIV) and flexible deformations can arise during operation. This paper presents experimental tests on a segmented free-hanging marine riser used for deep-sea mining, focusing on the vortex-induced vibration. The riser was formed by connecting pipe sections using flanges, with the top fixed and a lumped mass block added at the bottom to simulate the lifting pump and buffer station, resulting in weakly constrained boundary conditions. By employing the modal superposition principle and the wavelet time-frequency method, we comprehensively investigated the response characteristics of the typical pipe sections and the coupled oscillation of the riser's vibration modes. During the experiment, two important phenomena that differed from previous VIV tests were observed. Firstly, at low reduced velocities (Ur ≤ 7.77), the dominant frequency no longer conformed to the doubling principle in both directions but remained consistent. Secondly, the weak constraint effect of the concentration of mass at the bottom disrupts the formation of vortex shedding, thereby reducing the bending response of the CF direction of the bottom pipe sections. Meanwhile, the drag force enhances the bending response of the IL direction. Additionally, the middle and bottom pipe sections of the riser exhibited obvious mode competition, with the dominant mode often followed by several subordinate modes with considerable vibration energy.

Economic and environmental impact assessments of a newly designed energy system for marine applications

Marine transportation via the world's oceans is a critical way to convey goods and fuels between continents that cannot be performed cost-effectively by any other means. However, big ships heavily rely on fossil fuels, aggravating global carbon emissions. A key resolution to this dilemma is to employ clean fuels to reduce carbon emissions. This research paper introduces a new hybrid compound marine engine comprising a gas turbine, a solid oxide fuel cell, and a steam Rankine cycle. Three types of analyses, such as exergy, exergoeconomic, and exergoenvironmental analyses, are conducted on this proposed engine. It is found that the engine can produce a power of 15.5 MW, which is more than 48% compared to the traditional marine engine power, and the engine performance has up to 61% energy efficiency and 43% exergy efficiency. However, the exergetic efficiency of this engine based on fuel and product principal is 60%, which is more than 17% compared to its exergy efficiency. This engine has a 218 $/h Levelized cost rate and 139 mPt/h environmental rate. Finally, the average overall specific product exergy cost and environment are obtained to be 59 $/GJ and 20 mPt/MJ. By comparing five fuel blends, methane and hydrogen are the most economical and have the least impact on the environment; the second option is ethanol blend.

Ambient Noise Tomography for Coral Islands

As valuable land in the ocean, coral islands are not only important bases for making use of marine resources and protecting marine rights and interests, but also important for breakthrough research in many fields of earth science. Hence, the economical and efficient determination of the underground structure of coral islands has become significant in coral island engineering geology, but remains challenging for traditional marine geophysical prospecting and drilling methods. While ambient noise tomography with dense arrays has been widely used in continental regions, its applicability to coral islands remains undetermined. In this study, based on the data recorded by a dense array on an isolated coral island in the South China Sea, we analyzed the ambient noise characteristics and obtained a 3D subsurface structure of the coral island using ambient noise tomography. We made the following findings: ① The ambient noise frequencies can be roughly categorized into three levels: < 1, 1–5, and > 5 Hz. The spectral characteristics of the noise below 5 Hz were consistent at different stations, but there were significant differences in the characteristics of the noise above 5 Hz. ② For ambient noise frequencies below 5 Hz, cross-correlation functions with high quality could be obtained with only 24 h of waveform data. However, it was difficult to extract meaningful cross-correlation functions for ambient noise frequencies above 5 Hz. ③ The S-wave velocity in the coral island was higher toward the sea and lower toward the lagoon, which was consistent with the high degree of cementation of the outer reef flat stratum on the seaward side. ④ There were two low-velocity horizons at 25–75 and 200–300 m, which were in good agreement with the high-porosity horizons that were revealed by drilling core samples, reflecting the weathering history of the reef. Our research demonstrates that ambient noise tomography is a potentially economical, efficient, and environmentally friendly method for the geological prospecting of coral reefs.

Hydrodynamic Investigation on Floating Offshore Wind Turbine Platform Integrated with Porous Shell

As the siting of wind turbines increasingly transitions from shallow water to offshore deep-water locations, improving the platform stability of floating offshore wind turbines is becoming a growing concern. By coupling a porous shell commonly used in traditional marine structures, with a FOWT (floating wind turbine platform), a new spar-buoy with a porous shell was designed. A numerical model investigating the coupling effect of the aero-hydro-mooring system is developed, and the results of the motion response are compared with the OC3-Hywind spar. The motion response of the two platforms was simulated in the time-domain with the incident wave period varied in the range of 5~22 s. The exciting wave force with added mass and radiation damping of the spar with the porous shell is compared with the OC3-Hywind spar. The results demonstrate that the motion response amplitude of the spar with the porous shell decreases in all three main motion freedoms (i.e., surge, heave and pitch, etc.), among which the heave motions are most significantly attenuated. The study shows that the coupling of porous shells with a floating platform to achieve the reduced motion responses is feasible and can be an innovative structure for the development of deep-sea offshore floating wind turbines.

The effect of traditional diet on glucose homoeostasis in carriers and non-carriers of a common TBC1D4 variant in Greenlandic Inuit: a randomised crossover study.

Consumption of traditional foods is decreasing amid a lifestyle transition in Greenland as incidence of type 2 diabetes (T2D) increases. In homozygous carriers of a TBC1D4 variant, conferring postprandial insulin resistance, the risk of T2D is markedly higher. We investigated the effects of traditional marine diets on glucose homoeostasis and cardio-metabolic health in Greenlandic Inuit carriers and non-carriers of the variant ina randomised crossover study consisting of two 4-week dietary interventions: Traditional (marine-based, low-carbohydrate) and Western (high in imported meats and carbohydrates). Oral glucose tolerance test (OGTT, 2-h), 14-d continuous glucose and cardio-metabolic markers were assessed to investigate the effect of diet and genotype. Compared with the Western diet, the Traditional diet reduced mean and maximum daily blood glucose by 0·17 mmol/l (95 % CI 0·05, 0·29; P = 0·006) and 0·26 mmol/l (95 % CI 0·06, 0·46; P = 0·010), respectively, with dose-dependency. Furthermore, it gave rise to a weight loss of 0·5 kg (95 % CI; 0·09, 0·90; P = 0·016) relative to the Western diet and 4 % (95 % CI 1, 9; P = 0·018) lower LDL:HDL-cholesterol, which after adjustment for weight loss appeared to be driven by HDL elevation (0·09 mmol/l (0·03, 0·15), P = 0·006). A diet-gene interaction was indicated on insulin sensitivity in the OGTT (p = 0·093), which reflected a non-significant increase of 1·4 (-0·6, 3·5) mmol/l in carrier 2-h glucose. A Traditional diet marginally improved daily glycaemic control and plasma lipid profile compared with a Westernised diet in Greenlandic Inuit. Possible adverse effects on glucose tolerance in carriers of the TBC1D4 variant warrant further studies.

A comprehensive review of emission reduction technologies for marine transportation

The marine environment is experiencing significant impacts due to increased shipping traffic. The maritime industry must develop a low-carbon shipping strategy to comply with the increasingly strict emission regulations. This paper comprehensively reviews various decarbonization technologies, including navigation systems, hull design configuration, propulsion and power systems, and alternative fuels. By comparing a wide range of technologies in terms of their emission reduction potential and economic feasibility, this paper is intended to provide a full picture of alternative methods for future green shipping. Alternative fuels and hybrid power systems are found to have high potential for reducing carbon emissions and enhancing sustainability. The type of ship, its design configurations, and operation parameters affect the performance of optimal weather routing systems. With the current maritime policy and technological development, the transition from traditional marine fuel to liquefied natural gas can act as a temporary solution and provide significant decarbonization for maritime transportation. The emission reduction potential can be further enhanced with alternative fuels combined with hybrid power systems with high control flexibility.

Parallel Mirrors Based Marine Predator Optimization Algorithm with Deep Learning Model for Quality and Shelf-Life Prediction of Shrimp

Automatic classification and assessment of shrimp freshness plays a major role in aquaculture industry. Shrimp is one of the highly perishable seafood, because of its flavor and excellent nutritional content. Given the high amount of industrial production, determining the freshness of shrimp quickly and precisely is difficult. Instead of using feature-engineering-based techniques, a novel hybrid classification approach is proposed by combining the strength of convolutional neural networks (CNN) and Marine Predators Algorithm (MPA) for shrimp freshness diagnosis. In order to choose the best hyperparameter values, marine predator algorithm is improved using Parallel Mirrors Technique (PMPA). The proposed methodology employs a pretrained CNN model termed EfficientNet (ENet), which is combined with the PMPA algorithm to form the PMPA-ENet architecture. The proposed approach yields high performance while also reducing computational complexity. The result showed that proposed model achieved an accuracy and F-score of 98.62% and 97.25% for assessment of freshness in shrimp. PMPA's effectiveness in determining optimal values is compared to four different meta-heuristic algorithms hybridized with ENet including Particle Swarm Optimization (PSO), Simple Genetic Algorithm (SGA), Whale Optimization Algorithm (WOA), and traditional Marine Predator Algorithm (MPA). The results indicated that PMPA-ENet algorithm provides better classification compared with other algorithms

The use and sustainable development of marine animal drugs by the Kinh people in Beibu Gulf

The Kinh people of China have historically migrated from Tushan and other areas of Vietnam since the 16th century. They are now settled in Fangchenggang City in the Beibu Gulf region of Guangxi, China. The local Kinh people have lived by fishing and have a rich fishing culture. Accordingly, the Kinh people of China have a long history of using traditional marine animal drugs for their daily medicinal needs. However, with the advent of modern medicine, there is a risk of losing the valuable traditional knowledge of marine animal drugs. Thus, this study aimed to document the types of marine animal drugs and related traditional knowledge of the Kinh people and explore the sustainability of their access to marine animal drugs. Ethnobiological methods, including snowball sampling and semi-structured interviews are used to collect information about the animal drugs used locally during the study. Through field investigations in the “Three Islands of Kinh,” we collected ethnozoological data on 61 marine animal drugs belonging to 52 families across six animal phyla. Chordata and Mollusca are the most represented phyla, while Arthropoda, Echinodermata, Sipuncula, and Cnidaria are less represented. According to the analysis, animal meat is the most frequent medicinal part; the Kinh prefer decoction or making soup, and internal administration is the most frequent use mode. Our statistical analysis revealed that nourishing was the most common purpose for the recorded marine animal drugs in the study area. Our study found that 6 documented species are listed as threatened on the IUCN Red List but receive little targeted protection. The article provides recommendations for protecting traditional knowledge, promoting sustainable development of marine resources, and conserving endangered species.

Improved Design of LNG Marine Loading Arm Docking Method Based on TRIZ Theory

The LNG marine loading arm is a critical component for transferring LNG from vessels to onshore receiving stations. However, currently, the operation of LNG marine loading arms is still faced with issues such as a slow docking speed and significant environmental impacts from waves and wind. In this paper, we propose a set of feasible improvement schemes for the traditional LNG marine loading arm based on the theory of inventive problem solving (TRIZ). We utilized tools such as functional models, causal chain analysis, contradiction analysis, and Su-Field model analysis to develop these schemes. Our proposed improvements include using machine vision and automatic control to replace manual work, conducting finite element analysis and topology optimization of the LNG marine loading arm to improve its structure, and innovating the design of the end structure of the LNG discharge arm.

The effect of sucrase-isomaltase deficiency on metabolism, food intake and preferences: protocol for a dietary intervention study

ABSTRACT In Greenland, traditional marine foods are increasingly being replaced by sucrose- and starch-rich foods. A knock-out c.273_274delAG variant in the sucrase-isomaltase (SI) gene is relatively common in Greenland, with homozygous carriers being unable to digest sucrose and some starch. The variant is associated with a healthier metabolic phenotype in Greenlanders, which is confirmed by SI-knockout mice. We aim to assess if the healthy phenotype is explained by metabolic and microbial differences and if food and taste preferences differ between SI-genotypes. This paper describes the protocol for a randomised cross-over trial conducted in Greenland in 2022 with two dietary interventions of three days; a traditional meat- and fish-rich diet and a starch-rich Western diet with 11 energy% sucrose. The power calculation showed that 22 homozygous SI-carriers and 22 non-carriers were sufficient to detect a 0.5 mmol/L difference in glycaemic variability (80% power, α=0.05). We enrolled 18 carriers and 20 non-carriers. We examined food preferences at baseline and collected samples before and after each intervention for metabolic, metabolome, and microbiome profiling. Analyses of samples have not been completed yet. The Ethics Committee of Greenland approved the study. Results will be disseminated in international peer-reviewed journals and to the general Greenlandic population. NCT05375656.

A review of artificial intelligence in marine science

Utilization and exploitation of marine resources by humans have contributed to the growth of marine research. As technology progresses, artificial intelligence (AI) approaches are progressively being applied to maritime research, complementing traditional marine forecasting models and observation techniques to some degree. This article takes the artificial intelligence algorithmic model as its starting point, references several application trials, and methodically elaborates on the emerging research trend of mixing machine learning and physical modeling concepts. This article discusses the evolution of methodologies for the building of ocean observations, the application of artificial intelligence to remote sensing satellites, smart sensors, and intelligent underwater robots, and the construction of ocean big data. We also cover the method of identifying internal waves (IW), heatwaves, El Niño-Southern Oscillation (ENSO), and sea ice using artificial intelligence algorithms. In addition, we analyze the applications of artificial intelligence models in the prediction of ocean components, including physics-driven numerical models, model-driven statistical models, traditional machine learning models, data-driven deep learning models, and physical models combined with artificial intelligence models. This review shows the growth routes of the application of artificial intelligence in ocean observation, ocean phenomena identification, and ocean elements forecasting, with examples and forecasts of their future development trends from several angles and points of view, by categorizing the various uses of artificial intelligence in the ocean sector.

Optimization of Vacuum Marination Process, Maximizing the Flavor Infusion of Sole Fish

The major problem facing the fish processing industry is reducing the marination process time and increasing the uptake of marinade. Previously, a marination bath has been utilized for this purpose with different combinations of acid and salt, which causes physiochemical changes in fish texture. The vacuum marination method seems to be a good way to solve this problem. In this study, the effect of the vacuum marination process was studied on the marination of sole fish. Two varieties of fish (fresh and frozen) and three levels of time (10, 20 and 30 minutes) were studied for their effect on marinade uptake. The marinade was used in the ratio of 1.2:10 spices to meat, respectively. Fresh samples were weighted, vacuum packed, and stored at 4–7 0C, whereas frozen samples were stored at -20 0C for 24 hours prior to marination and thawed at room temperature. After marination, percentage uptake, retention, and cooking loss of the marinade were calculated. It was concluded from the yield of marinated products that about 80% of marination takes place in the first 10 minutes of the process. After 10–20 minutes, there was no significant difference (p&gt;0.05), and only 1–2% of the marinade was consumed. The frozen samples show significantly (p≤ 0.05) higher yields and marinade uptake. After marination, the samples were stored at 0–4 0C and fried in vegetable oil until the center reached 70 0C. Cooking loss for this process was non-significant for both varieties of fish as it depends on the water-holding capacity of the meat, which remains the same for both cases. The use of vacuum marination reduced the marination time significantly from 4-6 hours to 10 minutes, and marinade uptake was improved. This process can be used as an alternative to traditional marination techniques.

Smartenance DC-DC On-Board Power Converters

Traditional marine power grids, using diesel motors/generators, pollute the atmosphere with their CO2 emissions and adverse particles. Nowadays, green energy supplies like solar systems and fuel cells play significant roles in the electrification of marine propulsion plants. In general, marine power systems with green energy units are often considered as a kind of mobile DC microgrids under constant power loads (CPLs). However, since the CPLs impose nonlinearity and negative impedance instability on marine power systems, traditional linear controllers no longer stabilize the system under various disturbances. This motivated this brief to develop a non-integer model predictive control for the accurate control of DC/DC converters with CPLs to stabilize the main bus voltage and current in the full-electric ferry ship. In practice, the stability of ship systems is highly threatened due to the negative-independence effect of CPLs. To address the adverse challenges of CPLs, the deep deterministic policy gradient (DDPG) with actor and critic neural networks (NNs) is applied to effectively design the coefficients embedded in the non-integer MPC. In this approach, the actor NN provides the regulatory signals to adjust the non-integer MPC controller while the critic NN is trained to evaluate the quality of actions of actor NN. The experimental results with comparative analysis are carried out to validate the accuracy of the non-integer MPC under the change in the CPL’s power. The results demonstrated that the proposed controller offers a higher level of robustness than the state-of-art-schemes.

Mitigation effect of flywheel energy storage on the performance of marine gas turbine DC microgrid under high-power load mutation

Due to the slow response of output power of the traditional marine micro gas turbine, the directly connecting of high-power load to a shipboard micro gas turbine power generation system usually causes large power imbalance and instability instantly. To address this issue, a flywheel energy storage system (FESS) is applied to compensate the transient power changes, mitigate load fluctuations and maintain the voltage of the shipboard direct current (DC) bus. Based on a practical 100 kW micro gas turbine generator set, a detailed model of DC microgrid for the micro gas turbine generation system including micro gas turbine, FESS, synchronous generator, excitation system and load is established. The coordinated control strategy of micro gas turbine, FESS and load system is designed. The mitigation effects of FESS on marine gas turbine DC microgrid under high-power load mutation are explored by performing simulation with sudden load changes of 25%, 50% and 75% rated power and comparing the performance with and without FESS. The effectiveness of the control strategy has been verified by simulation analysis. The simulation results show that by reasonably designing the coordinated control strategy, the fluctuation of the power system can be effectively mitigated when sudden load, especially high-power sudden load is considered. The stability of the marine gas turbine microgrid has been greatly improved.

An online path planning algorithm for autonomous marine geomorphological surveys based on AUV

This paper proposed a data-driven bi-pattern (DDBP) path planning algorithm for ocean geomorphological surveys based on Autonomous Underwater Vehicles (AUVs). When an AUV conducts surveys in unknown areas, it uses the observation data of real-time side-scan sonar to conduct environment modeling to drive independent online path re-planning (PRP) according to the feature density of the interesting targets. Based on the DDBP algorithm, the AUV can autonomously focus on regions with rich target distribution and deviate from regions with sparse target distribution without prior knowledge of the task region. The quality and efficiency of the AUV-based surveys can be improved by focusing on the underwater detection area with high feature density. The DDBP algorithm includes two patterns: rough and fine scan, and the corresponding planning pattern is selected according to the distribution of the detected targets. AUV performs online PRP in the corresponding pattern according to the pre-identified strategy set. We conducted simulation experiments and selected sand waves and fish reefs as natural and artificial structures to conduct typical marine survey tests. Compared with the traditional marine survey method, the survey efficiency was increased by 33.6% and 29.6%, respectively, in the two DDBP survey experiments for sand waves; the efficiency increased by 32.9% and 36.7%, respectively, in the two groups of DDBP survey experiments on artificial reefs. The proposed general technical framework for online path planning driven by real-time observation data has good application prospects in underwater archaeology, rapid understanding of specific targets on the seafloor, and search of specific targets.

Marine Radar Oil Spill Extraction Based on Texture Features and BP Neural Network

Marine oil spills are one of the major threats to marine ecological safety, and the rapid identification of oil films is of great significance to the emergency response. Marine radar can provide data for marine oil spill detection; however, to date, it has not been commonly reported. Traditional marine radar oil spill research is mostly based on grayscale segmentation, and its accuracy depends entirely on the selection of the threshold. With the development of algorithm technology, marine radar oil spill extraction has gradually come to focus on artificial intelligence, and the study of oil spills based on machine learning has begun to develop. Based on X-band marine radar images collected from the Dalian 716 incident, this study used image texture features, the BP neural network classifier, and threshold segmentation for oil spill extraction. Firstly, the original image was pre-processed, to eliminate co-channel interference noise. Secondly, texture features were extracted and analyzed by the gray-level co-occurrence matrix (GLCM) and principal component analysis (PCA); then, the BP neural work was used to obtain the effective wave region. Finally, threshold segmentation was performed, to extract the marine oil slicks. The constructed BP neural network could achieve 93.75% classification accuracy, with the oil film remaining intact and the segmentation range being small; the extraction results were almost free of false positive targets, and the actual area of the oil film was calculated to be 42,629.12 m2. The method proposed in this paper can provide a reference for real-time monitoring of oil spill incidents.