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J. Mar. Sci. Eng., Volume 8, Issue 11 (November 2020) – 126 articles

Cover Story (view full-size image): Collections in two submarine caves of Lesvos Island (Aegean Sea) provided colonies of cheilostome bryozoans assigned to Onychocella marioni Jullien, 1882, O. vibraculifera Neviani, 1895, and Smittipora disjuncta Canu and Bassler, 1930, and a species previously reported as Onychocellidae sp. 1. This material allowed detailed observations and first scanning electron microscopy of some diagnostic characters leading to (i) updating the descriptions of these four species; (ii) resurrecting Floridinella arculifera Canu and Bassler, 1927, previously synonymised with Caleschara minuta (Maplestone, 1909), suggesting for it the new combination Tretosina arculifera; (iii) and introducing the new genus Bryobifallax for S. disjuncta. (The cover photo was taken by Vasilis Gerovasileiou) Vew this paper.
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Open AccessArticle
Digital Technologies for the Sustainable Development of the Accessible Underwater Cultural Heritage Sites
J. Mar. Sci. Eng. 2020, 8(11), 955; https://doi.org/10.3390/jmse8110955 - 23 Nov 2020
Viewed by 422
Abstract
In recent years, the development in digital technologies such as Augmented Reality (AR) and Virtual Reality (VR) has evolved rapidly. These technologies are currently in the process of creating driving change in the Cultural and Creative Industries (CCIs), representing innovative means to share [...] Read more.
In recent years, the development in digital technologies such as Augmented Reality (AR) and Virtual Reality (VR) has evolved rapidly. These technologies are currently in the process of creating driving change in the Cultural and Creative Industries (CCIs), representing innovative means to share information, facilitating access and increasing the value and public awareness on Cultural and Natural Heritage. This is particularly relevant for underwater environments, where the most interesting cultural and naturalistic sites are accessible only to scuba divers, or not accessible at all, due to depth and/or environmental constraints. In addition, in underwater sites, guided diving tours are carried out by professionals that usually describe the area to be visited during the predive briefings; such step is needed due to the impossibility of underwater verbal communication without dedicated equipment, a practice very rarely adopted for recreational diving. So, these difficulties make it almost impossible to replicate under the sea, the guided tour approach that is usually offered in on-land museums. Considering such limitations, several technological applications are emerging to increase the accessibility underwater and enrich users’ experience both for divers and nondivers. This work aims to identify the potential of underwater sites (either cultural or natural) to support the development of sustainable tourism (economic, environmental, cultural and social) in the Mediterranean. Moreover, it focuses on supplying local/regional authorities and stakeholders with a multidisciplinary plan for managing Underwater Museums and Knowledge Centres, by promoting innovation in the diving industry and improving users’/tourists’ experience through value-added services and cutting-edge technologies. Full article
(This article belongs to the Special Issue Advanced Technologies for Maritime and Underwater Archaeology)
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Open AccessFeature PaperArticle
Financial Analysis of Automated Container Terminal Capacity from the Perspective of Terminal Operating Company
J. Mar. Sci. Eng. 2020, 8(11), 954; https://doi.org/10.3390/jmse8110954 - 23 Nov 2020
Viewed by 226
Abstract
This study examines the financially feasibility of the proper terminal capacity by each berth size of the automatic container terminal (ACT) from the perspective of Terminal Operating Company (TOC). ACT is a highly productive and eco-friendly port facility, but it requires a lot [...] Read more.
This study examines the financially feasibility of the proper terminal capacity by each berth size of the automatic container terminal (ACT) from the perspective of Terminal Operating Company (TOC). ACT is a highly productive and eco-friendly port facility, but it requires a lot of capital investment. Thus, the investment of ACT should consider the TOC’s operating profit preservation to determine the proper terminal capacity. In this study, we attempt to conduct financial analysis using the net present value method and estimate breakeven handling volume of five berth sizes (nine, five, four, three, and two berths). In particular, as the aim of this study is to propose a capacity model of ACT, the model must be able to adapt to a variety of situations reflecting the number of berths and financial discount rate. The case study focused on the new port of Busan, introducing ACT. As a result, the breakeven terminal capacity changes from 560,421 TEU of the 9-berth model to 633,102 TEU of the 2-berth model, applying a 4.5% standard discount ratio. In a sensitivity test considering the change in discount rate and the size of the berth at the same time, the net present value (NPV) has a positive value at the level of at least 550,000 TEU (nine berths and 3.5% discount rate) and up to 650,000 TEU (two berths and 5.5% discount rate). The method of optimizing financial efficiency by analyzing the appropriate loading capacity will be an important support tool in decision-making by providing the analysis results and reasonable information obtained during the analysis process to the TOC, the main stakeholder in the adoption of ACT. Full article
(This article belongs to the Special Issue The Strategy of Smart Port)
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Open AccessArticle
A Line Ship Emissions while Manoeuvring and Hotelling—A Case Study of Port Split
J. Mar. Sci. Eng. 2020, 8(11), 953; https://doi.org/10.3390/jmse8110953 - 23 Nov 2020
Viewed by 273
Abstract
Strategically, the Republic of Croatia, with its economy focused on tourism, is directly connected to the sea and coastal area, and integrated management of this area contributes to the sustainable development strategy. Worldwide, the problem of atmospheric pollution from maritime traffic is a [...] Read more.
Strategically, the Republic of Croatia, with its economy focused on tourism, is directly connected to the sea and coastal area, and integrated management of this area contributes to the sustainable development strategy. Worldwide, the problem of atmospheric pollution from maritime traffic is a poorly researched area, especially when this type of traffic is continuously growing. On the example of Port Split, the paper aims to present the following emission, carbon dioxide (CO2), nitrogen oxides (NOX), carbon monoxide (CO), volatile organic compounds (VOC), sulphur dioxide (SO2), particulate matter (PM) and black carbon, of line vessels during manoeuvring and hotelling phase for 2017, 2018 and 2019. Furthermore, the statistical analysis and appropriate conclusions have been performed on CO2 since all other emissions are linearly dependent. From the analyses in the hotelling and manoeuvring phase of line ships, it can be concluded that during 2019 there was a slight increase in emissions, but overall there was no significant increase in the number of line vessels and increased traffic. The obtained results of case study of port Split provide recommendations leading to further reduction of harmful gas emission, monitoring them, and integrating it into management of urban ports. Full article
(This article belongs to the Section Ocean Engineering)
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Open AccessArticle
A Study on Enhancement of Fish Recognition Using Cumulative Mean of YOLO Network in Underwater Video Images
J. Mar. Sci. Eng. 2020, 8(11), 952; https://doi.org/10.3390/jmse8110952 - 22 Nov 2020
Viewed by 254
Abstract
In the underwater environment, in order to preserve rare and endangered objects or to eliminate the exotic invasive species that can destroy the ecosystems, it is essential to classify objects and estimate their number. It is very difficult to classify objects and estimate [...] Read more.
In the underwater environment, in order to preserve rare and endangered objects or to eliminate the exotic invasive species that can destroy the ecosystems, it is essential to classify objects and estimate their number. It is very difficult to classify objects and estimate their number. While YOLO shows excellent performance in object recognition, it recognizes objects by processing the images of each frame independently of each other. By accumulating the object classification results from the past frames to the current frame, we propose a method to accurately classify objects, and count their number in sequential video images. This has a high classification probability of 93.94% and 97.06% in the test videos of Bluegill and Largemouth bass, respectively. The proposed method shows very good classification performance in video images taken of the underwater environment. Full article
(This article belongs to the Special Issue Machine Learning and Remote Sensing in Ocean Science and Engineering)
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Open AccessFeature PaperArticle
Size/Age Models for Monitoring of the Pink Sea Fan Eunicella verrucosa (Cnidaria: Alcyonacea) and a Case Study Application
J. Mar. Sci. Eng. 2020, 8(11), 951; https://doi.org/10.3390/jmse8110951 - 22 Nov 2020
Viewed by 197
Abstract
The pink sea fan Eunicella verrucosa is a habitat-forming octocoral living in the East Atlantic and in the Mediterranean Sea where, under proper circumstances, it can form large populations known as coral forests. Although these coral forests represent vulnerable marine ecosystems of great [...] Read more.
The pink sea fan Eunicella verrucosa is a habitat-forming octocoral living in the East Atlantic and in the Mediterranean Sea where, under proper circumstances, it can form large populations known as coral forests. Although these coral forests represent vulnerable marine ecosystems of great importance, these habitats are still poorly known, and their monitoring is almost non-existent to date. For this reason, we compared two different models to infer the age of E. verrucosa based on nondestructive measurements of the colonies’ size, in order to highlight strengths and weaknesses of the existing tools for a potential application in long-term monitoring. We also applied the two models on a case-study population recently found in the northwest Mediterranean Sea. Our results showed which model was more reliable from a biological point of view, considering both its structure and the results obtained on the case study. However, this model uses solely the height of the colonies as proxy to infer the age, while the total branch fan surface area could represent a more appropriate biometric parameter to monitor the size and the growth of E. verrucosa. Full article
(This article belongs to the Special Issue Benthic Species and Habitats)
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Open AccessFeature PaperArticle
A Modeling Study on the Influence of Sea-Level Rise and Channel Deepening on Estuarine Circulation and Dissolved Oxygen Levels in the Tidal James River, Virginia, USA
J. Mar. Sci. Eng. 2020, 8(11), 950; https://doi.org/10.3390/jmse8110950 - 21 Nov 2020
Viewed by 355
Abstract
The impact of channel deepening and sea-level rise on the environmental integrity of an estuary is investigated using a three-dimensional hydrodynamic-eutrophication model. The model results show that dissolved oxygen (DO) only experienced minor changes, even when the deep channel was deepened by 3 [...] Read more.
The impact of channel deepening and sea-level rise on the environmental integrity of an estuary is investigated using a three-dimensional hydrodynamic-eutrophication model. The model results show that dissolved oxygen (DO) only experienced minor changes, even when the deep channel was deepened by 3 m in the mesohaline and polyhaline regions of the James River. We found that vertical stratification decreased DO aeration while the estuarine gravitational circulation increased bottom DO exchange. The interactions between these two processes play an important role in modulating DO. The minor change in DO due to channel deepening indicates that the James River is unique as compared with other estuaries. To understand the impact of the hydrodynamic changes on DO, both vertical and horizontal transport timescales represented by water age were used to quantify the changes in hydrodynamic conditions and DO variation, in addition to traditional measures of stratification and circulation. The model results showed that channel deepening led to an increase in both gravitational circulation strength and vertical stratification. Saltwater age decreased and vertical exchange time increased with increases in channel depth. However, these two physical processes can compensate each other, resulting in minor changes in DO. A comparison of the impact of a sea-level rise of 1.0 m with channel deepening scenarios was conducted. As the sea level rises, the vertical transport time decreases slightly while the strength of gravitational circulation weakens due to an increase in mean water depth. Consequently, DO in the estuary experiences a moderate decrease. Full article
(This article belongs to the Section Physical Oceanography)
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Open AccessFeature PaperArticle
Revisiting Vertical Land Motion and Sea Level Trends in the Northeastern Adriatic Sea Using Satellite Altimetry and Tide Gauge Data
J. Mar. Sci. Eng. 2020, 8(11), 949; https://doi.org/10.3390/jmse8110949 - 21 Nov 2020
Viewed by 259
Abstract
We propose a revisited approach to estimating sea level change trends based on the integration of two measuring systems: satellite altimetry and tide gauge (TG) time series of absolute and relative sea level height. Quantitative information on vertical crustal motion trends at six [...] Read more.
We propose a revisited approach to estimating sea level change trends based on the integration of two measuring systems: satellite altimetry and tide gauge (TG) time series of absolute and relative sea level height. Quantitative information on vertical crustal motion trends at six TG stations of the Adriatic Sea are derived by solving a constrained linear inverse problem. The results are verified against Global Positioning System (GPS) estimates at some locations. Constraints on the linear problem are represented by estimates of relative vertical land motion between TG couples. The solution of the linear inverse problem is valid as long as the same rates of absolute sea level rise are observed at the TG stations used to constrain the system. This requirement limits the applicability of the method with variable absolute sea level trends. The novelty of this study is that we tried to overcome such limitations, subtracting the absolute sea level change estimates observed by the altimeter from all relevant time series, but retaining the original short-term variability and associated errors. The vertical land motion (VLM) solution is compared to GPS estimates at three of the six TGs. The results show that there is reasonable agreement between the VLM rates derived from altimetry and TGs, and from GPS, considering the different periods used for the processing of VLM estimates from GPS. The solution found for the VLM rates is optimal in the least square sense, and no longer depends on the altimetric absolute sea level trend at the TGs. Values for the six TGs’ location in the Adriatic Sea during the period 1993–2018 vary from −1.41 ± 0.47 mm y−1 (National Research Council offshore oceanographic tower in Venice) to 0.93 ± 0.37 mm y−1 (Rovinj), while GPS solutions range from −1.59 ± 0.65 (Venice) to 0.10 ± 0.64 (Split) mm y−1. The absolute sea level rise, calculated as the sum of relative sea level change rate at the TGs and the VLM values estimated in this study, has a mean of 2.43 mm y−1 in the period 1974–2018 across the six TGs, a mean standard error of 0.80 mm y−1, and a sample dispersion of 0.18 mm y−1. Full article
(This article belongs to the Section Physical Oceanography)
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Open AccessArticle
The Effect of Tropical Cyclone Nicholas (11–20 February 2008) on Sea Level Anomalies in Indonesian Waters
J. Mar. Sci. Eng. 2020, 8(11), 948; https://doi.org/10.3390/jmse8110948 - 20 Nov 2020
Viewed by 221
Abstract
As reported extensively in both electronic and print media in Indonesia, high wave and anomalously high sea level phenomena occurred in February 2008 in Indonesian waters, mainly along the western coast of Sumatra and the southern coasts of Java-Bali. Tropical Cyclone (TC) Nicholas, [...] Read more.
As reported extensively in both electronic and print media in Indonesia, high wave and anomalously high sea level phenomena occurred in February 2008 in Indonesian waters, mainly along the western coast of Sumatra and the southern coasts of Java-Bali. Tropical Cyclone (TC) Nicholas, occurring in northwestern coastal waters of Australia between 11 and 20 February 2008, might have contributed to the existence of these phenomena in the Indonesian region. This study focused on investigating the effect of TC Nicholas on the increases in sea levels in the Indonesian waters by analyzing residual water levels (non-astronomic tide). In this regard, a storm tide event (the sum of the astronomical tide and storm surge generated by the TC Nicholas) was simulated in this region using the Regional Ocean Modeling System (ROMS). The residual water levels were obtained by removing the tidal part (astronomic tide) from the ROMS simulated total water levels. In addition, to confirm possible influences of TC Nicholas, a lagged correlation analysis was applied between atmospheric pressure at the center of TC Nicholas and residual water level oscillations in the Indonesian waters. It was found that the residual water levels showed a strong correlation with the atmospheric pressure at the center of TC Nicholas in some areas of the Indonesian seas, such as the western coast of Sumatra, the southern coast of Java, Lesser Sunda Islands, and the southern coast of Papua. The increased sea levels on the western coast of Sumatra are up to 16 cm, with TC Nicholas leading the residual water level by 4.18 days (TL: time lag). Meanwhile, they are up to 20 cm (TL = 5.75 days), 21 cm (TL = 1.12 days), and 38 cm (TL = 3.96 days) on the southern coast of Java, the Lesser Sunda Islands, and the southern coast of Papua, respectively. The results of this study could be used as an initial assessment to investigate the most vulnerable Indonesian coastal areas to the impact of the TC and they might be significantly beneficial for designing both a proper disaster risk reduction program and investment policies in the region, particularly in the context of flood risk reduction and adaptation. Full article
(This article belongs to the Special Issue Sea Level Rise: Drivers, Variability and Impacts)
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Open AccessReview
Numerical Assessment of Onshore Wave Energy in France: Wave Energy, Conversion and Cost
J. Mar. Sci. Eng. 2020, 8(11), 947; https://doi.org/10.3390/jmse8110947 - 20 Nov 2020
Viewed by 216
Abstract
There are few general analyses of the interest of onshore wave energy converters (onshore WEC) in terms of resources, efficiency and cost. The case of The Channel on the Atlantic coast of France is chosen here to illustrate the issues related to onshore [...] Read more.
There are few general analyses of the interest of onshore wave energy converters (onshore WEC) in terms of resources, efficiency and cost. The case of The Channel on the Atlantic coast of France is chosen here to illustrate the issues related to onshore WEC development. The paper presents a list of potential sites with their characteristics and a more in-depth analysis of a few sites. For four onshore WEC families, the production is given with a method of calculating the efficiency and economic analysis is carried out to estimate the energy cost at two selected sites. Annual wave power levels are maximum in Bayonne with 24 kW/m, and the lengths of useful dikes vary from 60 m in Molène up to 4000 m in Cherbourg. Wave reflection on the dike is an advantage in terms of energy production. The oscillating flaps constitute the systems with the highest efficiency, and the float systems have the lowest levelized cost of energy (LCoE), followed closely by the oscillating flaps. Oscillating water columns and overtopping systems have nearly five times these LCoEs. With mass production, costs of oscillating floats and flaps will approach those of other renewable energies such as solar and wind power. Full article
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Open AccessArticle
Optimization of a Multiple Injection System in a Marine Diesel Engine through a Multiple-Criteria Decision-Making Approach
J. Mar. Sci. Eng. 2020, 8(11), 946; https://doi.org/10.3390/jmse8110946 - 20 Nov 2020
Cited by 1 | Viewed by 195
Abstract
In this work, a numerical model was developed to analyze the performance and emissions of a marine diesel engine, the Wärtsilä 6L 46. This model was validated using experimental measurements and was employed to analyze several pre-injection parameters such as pre-injection rate, duration, [...] Read more.
In this work, a numerical model was developed to analyze the performance and emissions of a marine diesel engine, the Wärtsilä 6L 46. This model was validated using experimental measurements and was employed to analyze several pre-injection parameters such as pre-injection rate, duration, and starting instant. The modification of these parameters may lead to opposite effects on consumption and/or emissions of nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC). According to this, the main goal of the present work is to employ a multiple-criteria decision-making (MCDM) approach to characterize the most appropriate injection pattern. Since determining the criteria weights significantly influences the overall result of a MCDM problem, a subjective weighting method was compared with four objective weighting methods: entropy, CRITIC (CRiteria Importance Through Intercriteria Correlation), variance, and standard deviation. The results showed the importance of subjectivism over objectivism in MCDM analyses. The CRITIC, variance, and standard deviation methods assigned more importance to NOx emissions and provided similar results. Nevertheless, the entropy method assigned more importance to consumption and provided a different injection pattern. Full article
(This article belongs to the Special Issue Marine Engines Performance and Emissions)
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Open AccessFeature PaperArticle
A Review of the Production, Recycling and Management of Marine Plastic Pollution
J. Mar. Sci. Eng. 2020, 8(11), 945; https://doi.org/10.3390/jmse8110945 - 20 Nov 2020
Viewed by 306
Abstract
The human attachment to plastic has intensified recently due to its lightweight, versatility, low-cost and durability and so has the damage to the marine environment as marine plastic pollution has correspondingly increased. As a result, there has been increasing concern on the issue [...] Read more.
The human attachment to plastic has intensified recently due to its lightweight, versatility, low-cost and durability and so has the damage to the marine environment as marine plastic pollution has correspondingly increased. As a result, there has been increasing concern on the issue of marine plastic pollution. Policy-based organizations such as the United Nations Environment Programme have drawn public attention to the scope, magnitude and impacts of marine pollution in recent decades. Research on marine pollution can play a significant role in contributing to policy-making processes in support of the United Nations Sustainable Development Goal on Life Below Water (SDG 14), by providing scientific analysis on the effects and sources of marine plastic pollution. This paper provides a theoretical and empirical overview of marine plastic pollution and its potential effects on marine ecosystems. It also discusses SDGs that are relevant to marine plastic pollution and suggest priorities for further research. Full article
(This article belongs to the Special Issue Ocean Conservation and Pollution in an Era of Blue Economy)
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Open AccessArticle
Advances in the Coastal and Submarine Groundwater Processes: Controls and Environmental Impact on the Thriassion Plain and Eleusis Gulf (Attica, Greece)
J. Mar. Sci. Eng. 2020, 8(11), 944; https://doi.org/10.3390/jmse8110944 - 20 Nov 2020
Viewed by 187
Abstract
This study focuses on the hydrogeological conditions in the coastal (Thriassion plain) and submarine (Eleusis Gulf) environment of West Attica, Greece. Up to now, the predominant aspect for the Thriassion plain groundwater—hosted within the Neogene-Quaternary sediments—was its direct hydraulic contact with the seawater. [...] Read more.
This study focuses on the hydrogeological conditions in the coastal (Thriassion plain) and submarine (Eleusis Gulf) environment of West Attica, Greece. Up to now, the predominant aspect for the Thriassion plain groundwater—hosted within the Neogene-Quaternary sediments—was its direct hydraulic contact with the seawater. Due to that, the coastal plain groundwater is strongly believed to be of brackish quality irrespective of the local hydrodynamic conditions. Our major goal is to evaluate the actual mechanism controlling the groundwater flow, the origin and distribution of saline water, and the existence of fresh groundwater in the submarine environment. We summarize the following: (1) groundwater of the Thriassion plain is partly discharged as an upwards leakage from deeper aquifers, (2) modern direct seawater intrusion is not possible in the Neogene-Quaternary sediments, and (3) fresh groundwater possibly exists below the sea floor of the Eleusis Gulf. The results may serve as hint of further research in groundwater resources below the Mediterranean Sea floor, and, consequently, a new perspective on water resource management could emerge. Full article
(This article belongs to the Special Issue Climate Change and Marine Geological Dynamics)
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Open AccessArticle
A Novel Method for Simultaneous Removal of NO and SO2 from Marine Exhaust Gas via In-Site Combination of Ozone Oxidation and Wet Scrubbing Absorption
J. Mar. Sci. Eng. 2020, 8(11), 943; https://doi.org/10.3390/jmse8110943 - 20 Nov 2020
Viewed by 199
Abstract
The stringent international regulations on marine emission abatement have exerted a huge push on the development of marine desulfurization and denitrification technologies. However, for the traditional vessels driven by large two-stroke diesel engines, simultaneous removal of NOx and SO2 is still [...] Read more.
The stringent international regulations on marine emission abatement have exerted a huge push on the development of marine desulfurization and denitrification technologies. However, for the traditional vessels driven by large two-stroke diesel engines, simultaneous removal of NOx and SO2 is still a big challenge at present. Here, a one-stage ozone oxidation combined with in-situ wet scrubbing for simultaneous removal of NO and SO2 is proposed. A series of experiments were performed based on a bench-scale reaction system. The results showed that in-situ wet scrubbing could effectively decrease flue gas temperature, and then suppress the thermal decomposition of ozone, which was beneficial for improve oxidant utilization. Meanwhile, the in-situ combination of ozone injection and wet scrubbing was in favor of improving the selectivity oxidation of NO over SO2 by ozone, which was possibly due to the high aqueous solubility of SO2 in water. Aiming to reduce the electric power consumption by an ozone generating system, O3/NO molar ratio was kept as low as possible. A complete removal of SO2 and a high NOx removal efficiency could be achieved through the introduction of other oxidative additives in scrubbing solution. This integrated system designed for marine application was of great significance. Full article
(This article belongs to the Section Ocean Engineering)
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Open AccessArticle
Biomonitoring of the Application of Monoculture and Integrated Multi-Trophic Aquaculture (IMTA) Using Macrobenthic Structures at Tembelas Island, Kepulauan Riau Province, Indonesia
J. Mar. Sci. Eng. 2020, 8(11), 942; https://doi.org/10.3390/jmse8110942 - 19 Nov 2020
Viewed by 218
Abstract
Sustainable aquaculture needs to be considered when it comes to the utilization of water resources. The aim of this study was to apply biomonitoring using macrobenthic structures on both spatial and temporal applications of monoculture and integrated multi-trophic aquaculture (IMTA) at Tembelas Island, [...] Read more.
Sustainable aquaculture needs to be considered when it comes to the utilization of water resources. The aim of this study was to apply biomonitoring using macrobenthic structures on both spatial and temporal applications of monoculture and integrated multi-trophic aquaculture (IMTA) at Tembelas Island, Kepulauan Riau Province, Indonesia. Samples of sediment were taken from three fish farm locations, namely from an IMTA site, a monoculture site, and a reference site. Macrobenthic organisms obtained through rinsing, sieving, and sorting were then identified under a stereo-microscope. Diversity of the macrobenthic assemblages was analyzed with a Shannon-Wiener index (H’). Equitability was expressed through Pielou’s evenness index. Finally, Bray-Curtis’ non-metric multi-dimensional scaling (NMDS) was used for similarities derived from log (X+1) transformed macrobenthic abundance to provide a visual representation of differences in their structure between sites over time. Results showed polychaetes exhibited differences in both variation and abundance of genera between the farm and reference site. The assemblage of macrobenthos at the IMTA site consisted of 9 genera of gastropods, 3 genera of bivalves, 5 genera of polychaetes, and 2 genera of crustaceans. At the monoculture site, 12 genera of gastropods, 4 genera of bivalves, 8 genera of polychaetes, 1 genera of crustaceans, and 1 genera of ophiuroid were observed. A relatively high abundance was observed at the reference site, with 27 genera of gastropods, 11 genera of bivalves, 3 genera of polychaetes, and 1 genera of crustacean. The favorable water conditions and possible absence of waste input from aquaculture resulting in a more suitable habitat for macrobenthic life may explain this relative abundance. Some of them were recognised as opportunistic taxa, i.e., Capitella sp., Heteromastus sp., and Lumbrinereis sp. Based on the diversity and evenness indices and the MNDS ordination, it can be concluded that the application of IMTA systems results in a suppressed or reduced potential impact on environmental disturbance due to aquacultural activities. Full article
(This article belongs to the Special Issue Marine Observation and Monitoring towards an Ecosystem Approach)
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Open AccessFeature PaperReview
Review of the Design and Technology Challenges of Zero-Emission, Battery-Driven Fast Marine Vehicles
J. Mar. Sci. Eng. 2020, 8(11), 941; https://doi.org/10.3390/jmse8110941 - 19 Nov 2020
Viewed by 232
Abstract
The paper deals with a critical review of unique problems and challenges related to the design and technology of zero-emission, battery driven, fast marine vehicles. The uniqueness of the ensuing ship design problem is the request to fit maximum battery capacity and to [...] Read more.
The paper deals with a critical review of unique problems and challenges related to the design and technology of zero-emission, battery driven, fast marine vehicles. The uniqueness of the ensuing ship design problem is the request to fit maximum battery capacity and to ensure minimum required power in order to achieve the set operational requirements for high service speed and sufficient range. The high-speed requirement is inherently connected with the request for minimum structural and lightship weight, while the design needs also to comply with set regulatory safety constraints. The underlying research is in the frame of the EU funded project TrAM (Transport: Advanced and Modular) and leads to the development and construction of a physical demonstrator for operation in the Stavanger area in Norway. The paper discusses the incurring critical issues, discusses the feasibility of the concept and concludes on the way ahead. Full article
(This article belongs to the Special Issue Zero Emission Shipping)
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Open AccessArticle
Polychaete Invasion May Lead to Biogeochemical Change in Host Marine Environment
J. Mar. Sci. Eng. 2020, 8(11), 940; https://doi.org/10.3390/jmse8110940 - 19 Nov 2020
Viewed by 268
Abstract
Marine invasive species may modify their host environment by altering ecosystem biogeochemistry. We hypothesized that the invasive polychaete Marenzelleria viridis in Baltic Sea areas increases sulfate reduction (SR) in sediment micro-zones surrounding its burrow. Consequently, higher free porewater sulfide (H2S) is [...] Read more.
Marine invasive species may modify their host environment by altering ecosystem biogeochemistry. We hypothesized that the invasive polychaete Marenzelleria viridis in Baltic Sea areas increases sulfate reduction (SR) in sediment micro-zones surrounding its burrow. Consequently, higher free porewater sulfide (H2S) is expected in sediments dominated by M. viridis than in corresponding sediments inhabited by the native polychaete Hediste diversicolor. In a thin-aquaria experiment, we found high SR rates (220 to 539 nmol cm−3 d−1) around the burrow walls of M. viridis as well as in surface and subsurface sediments with overall rates 2-fold higher than in defaunated control sediment. Similarly, an in situ survey revealed subsurface porewater H2S peaks moving upward towards the sediment surface in M. viridis inhabited areas. Accordingly, 50–85% higher porewater H2S was found almost year-round in these areas compared with H. diversicolor inhabited areas, suggesting that the invasion of M. viridis probably led to a substantial change in sediment biogeochemistry. In conclusion, M. viridis stimulates SR in sediment micro-zones and increases H2S in coastal sediments. Such change to more reducing conditions after the invasion may have critical environmental implications on, e.g., the distribution of H2S intolerant flora and fauna species. Full article
(This article belongs to the Special Issue Bioturbation in Marine Ecosystems: Current and Future Challenges)
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Open AccessArticle
Evaluating the Sensor-Equipped Autonomous Surface Vehicle C-Worker 4 as a Tool for Identifying Coastal Ocean Acidification and Changes in Carbonate Chemistry
J. Mar. Sci. Eng. 2020, 8(11), 939; https://doi.org/10.3390/jmse8110939 - 19 Nov 2020
Viewed by 481
Abstract
The interface between land and sea is a key environment for biogeochemical carbon cycling, yet these dynamic environments are traditionally under sampled. Logistical limitations have historically precluded a comprehensive understanding of coastal zone processes, including ocean acidification. Using sensors on autonomous platforms is [...] Read more.
The interface between land and sea is a key environment for biogeochemical carbon cycling, yet these dynamic environments are traditionally under sampled. Logistical limitations have historically precluded a comprehensive understanding of coastal zone processes, including ocean acidification. Using sensors on autonomous platforms is a promising approach to enhance data collection in these environments. Here, we evaluate the use of an autonomous surface vehicle (ASV), the C-Worker 4 (CW4), equipped with pH and pCO2 sensors and with the capacity to mount additional sensors for up to 10 other parameters, for the collection of high-resolution data in shallow coastal environments. We deployed the CW4 on two occasions in Belizean coastal waters for 2.5 and 4 days, demonstrating its capability for high-resolution spatial mapping of surface coastal biogeochemistry. This enabled the characterisation of small-scale variability and the identification of sources of low pH/high pCO2 waters as well as identifying potential controls on coastal pH. We demonstrated the capabilities of the CW4 in both pre-planned “autonomous” mission mode and remote “manually” operated mode. After documenting platform behaviour, we provide recommendations for further usage, such as the ideal mode of operation for better quality pH data, e.g., using constant speed. The CW4 has a high power supply capacity, which permits the deployment of multiple sensors sampling concurrently, a shallow draught, and is highly controllable and manoeuvrable. This makes it a highly suitable tool for observing and characterising the carbonate system alongside identifying potential drivers and controls in shallow coastal regions. Full article
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Open AccessArticle
Simulating the Trajectory and Biomass Growth of Free-Floating Macroalgal Cultivation Platforms along the U.S. West Coast
J. Mar. Sci. Eng. 2020, 8(11), 938; https://doi.org/10.3390/jmse8110938 - 18 Nov 2020
Viewed by 192
Abstract
Trajectory tracking and macroalgal growth models were coupled to support a novel macroalgae-harvesting concept known as the Nautical Off-shore Macroalgal Autonomous Device (NOMAD). The NOMAD consists of 5 km long carbon-fiber longlines that are seeded and free float southward along the U.S. West [...] Read more.
Trajectory tracking and macroalgal growth models were coupled to support a novel macroalgae-harvesting concept known as the Nautical Off-shore Macroalgal Autonomous Device (NOMAD). The NOMAD consists of 5 km long carbon-fiber longlines that are seeded and free float southward along the U.S. West Coast for approximately 3 months before harvesting off the California coast, taking advantage of favorable environmental conditions. The trajectory and macroalgal growth models were applied to answer planning questions pertinent to the techno-economic analysis such as identifying the preferred release location, approximate pathway, timing until harvest, and estimated growth. Trajectories were determined with the General NOAA Operational Modeling Environment (GNOME) model, using 11 years of current and wind data, determining probabilities by running nearly 40,000 Monte Carlo simulations varying the start time and location. An accompanying macroalgal growth model was used to estimate the growth of macroalgae based on the trajectory tracks and environmental forcing products, including light, temperature and nutrients. Model results show that NOMAD lines transit south in the months of April to September due to seasonal currents, taking approximately 3 months to reach Southern California. During transit, NOMAD lines are dispersed but typically avoid beaching or passing through marine sanctuaries. NOMAD lines can yield up to 30 kg wet weight per meter of cultivation line. Full article
(This article belongs to the Section Marine Biology)
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Open AccessArticle
Discussion on Coupling Effect in Structural Load of FOWT for Condensing Wind and Wave Bins for Spectral Fatigue Analysis
J. Mar. Sci. Eng. 2020, 8(11), 937; https://doi.org/10.3390/jmse8110937 - 18 Nov 2020
Viewed by 213
Abstract
Floating Offshore Wind Turbines (FOWTs) are subject to combined wind and wave loads. The response is not given as a simple sum of the wind-only response and wave-only response due to nonlinear coupling effects, which makes the structural analysis more complex and time-consuming. [...] Read more.
Floating Offshore Wind Turbines (FOWTs) are subject to combined wind and wave loads. The response is not given as a simple sum of the wind-only response and wave-only response due to nonlinear coupling effects, which makes the structural analysis more complex and time-consuming. When a spectral approach for the structural fatigue analysis is considered, it is necessary to accurately estimate the variance of the combined stress taking account of the coupling effect. In this study, firstly the characteristics of the combined response are investigated. It is found out the coupling effects are two-fold; one is the aerodynamic exciting load increase for the forced motion in the wave frequency range. The other is the aerodynamic damping effect due to the increase of the relative wind speed, which is prominent in the structural vibration frequency range. Mathematical models to account for these coupling effects are developed. Then, a series of simulations are performed on three types of FOWTs to validate the models. It is shown that the characteristics of the combined response are different among the three types of the platforms and the developed model can explain the increase/decrease of the variance of the combined stress when compared with two decoupled wave-only and wind-only simulations. Full article
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Open AccessArticle
Hybrid Partition-Based Patrolling Scheme for Maritime Area Patrol with Multiple Cooperative Unmanned Surface Vehicles
J. Mar. Sci. Eng. 2020, 8(11), 936; https://doi.org/10.3390/jmse8110936 - 18 Nov 2020
Viewed by 222
Abstract
Multi-robot cooperative patrolling systems have been extensively employed in the civilian and military fields, including monitoring forest fires, marine search-and-rescue, and area patrol. Multi-robot area patrol problems refer to the activity that a team of robots works cooperatively and regularly to visit the [...] Read more.
Multi-robot cooperative patrolling systems have been extensively employed in the civilian and military fields, including monitoring forest fires, marine search-and-rescue, and area patrol. Multi-robot area patrol problems refer to the activity that a team of robots works cooperatively and regularly to visit the key targets in the given area for security. Following consideration of the low cost and high safety of unmanned surface vehicles (USV), a team of USVs is organized to perform area patrol in a sophisticated maritime environment. In this paper, we establish a mathematical model considering the characteristics of the cooperative patrol task and the limited conditions of USVs. A hybrid partition-based patrolling scheme is proposed for a multi-USV system to visit targets with different importance levels in a maritime area. Firstly, a centralized area partition algorithm is utilized to partition the patrolling area according to the number of USVs. Secondly, a distributed path planning algorithm is applied to planning the patrolling path for each USV to visit the targets in a maritime environment to minimize the length of the patrolling path for the USV team. Finally, comparative experiments between the proposed scheme and other methods are carried out to validate the performance of the hybrid partition-based patrolling scheme. Simulation results and experimental analysis show the efficiency of the proposed hybrid partition-based patrolling scheme compared to several previous patrolling algorithms. Full article
(This article belongs to the Section Ocean Engineering)
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Open AccessArticle
Isolation, Identification, and Biochemical Characteristics of a Cold-Tolerant Chlorella vulgaris KNUA007 Isolated from King George Island, Antarctica
J. Mar. Sci. Eng. 2020, 8(11), 935; https://doi.org/10.3390/jmse8110935 - 18 Nov 2020
Viewed by 196
Abstract
A cold-tolerant unicellular green alga was isolated from a meltwater stream on King George Island, Antarctica. Morphological, molecular, and biochemical analyses revealed that the isolate belonged to the species Chlorella vulgaris. We tentatively named this algal strain C.vulgaris KNUA007 and investigated [...] Read more.
A cold-tolerant unicellular green alga was isolated from a meltwater stream on King George Island, Antarctica. Morphological, molecular, and biochemical analyses revealed that the isolate belonged to the species Chlorella vulgaris. We tentatively named this algal strain C.vulgaris KNUA007 and investigated its growth and lipid composition. We found that the strain was able to thrive in a wide range of temperatures, from 5 to 30 °C; however, it did not survive at 35 °C. Ultimate analysis confirmed high gross calorific values only at low temperatures (10 °C), with comparable values to land plants for biomass fuel. Gas chromatography/mass spectrometry analysis revealed that the isolate was rich in nutritionally important polyunsaturated fatty acids (PUFAs). The major fatty acid components were hexadecatrienoic acid (C16:3 ω3, 17.31%), linoleic acid (C18:2 ω6, 8.52%), and α-linolenic acid (C18:3 ω3, 43.35%) at 10 °C. The microalga was tolerant to low temperatures, making it an attractive candidate for the production of biochemicals under cold weather conditions. Therefore, this Antarctic microalga may have potential as an alternative to fish and/or plant oils as a source of omega-3 PUFA. The temperature tolerance and composition of C.vulgaris KNUA007 also make the isolate desirable for commercial applications in the pharmaceutical industry. Full article
(This article belongs to the Special Issue Taxonomy and Ecology of Marine Algae)
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Open AccessArticle
Evaluation of the Effects of the Enriched-Organic Diets Composition on European Sea Bass Welfare through a Multi-Parametric Approach
J. Mar. Sci. Eng. 2020, 8(11), 934; https://doi.org/10.3390/jmse8110934 - 17 Nov 2020
Viewed by 256
Abstract
Three groups of European sea bass (Dicentrarchus labrax) were fed for seven months, with either a conventional diet or two different organic diets, which contain organic vegetables and a natural antioxidant compound. The two organic diets differed themselves in terms of [...] Read more.
Three groups of European sea bass (Dicentrarchus labrax) were fed for seven months, with either a conventional diet or two different organic diets, which contain organic vegetables and a natural antioxidant compound. The two organic diets differed themselves in terms of raw proteins, fish oil, and lipid contents. Sea bass welfare condition was assessed in relation to these three diets, using 16 different indicators. These were: swimming activity (recovery test, muscle activity), haematological and serological stress indicators (haematocrit, haemoglobin, red-blood-cell count, cortisol, glucose, lactate), aspecific immunity parameter (lysozyme), indicators of exposure to organic contaminants (7-ethoxyresorufin-O-deethylase and glutathione-S-transferase), and growth parameters (weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio, and hepato-somatic index). Most of these parameters individually did not give consistent responses, but their integration can provide an accurate evaluation of the fish welfare conditions among the three diet experimental groups. The multiparametric approach outlined a comprehensive picture of sea bass physiological state. The principal component analysis and the multi-criteria-decision-analysis were found to be useful tools for an integrated fish welfare assessment, highlighting that the best welfare condition was achieved in the experimental group fed with the protein-rich organic diet. Full article
(This article belongs to the Special Issue New Perspectives in Sustainable Aquaculture)
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Open AccessArticle
21 May 2003 Boumerdès Earthquake: Numerical Investigations of the Rupture Mechanism Effects on the Induced Tsunami and Its Impact in Harbors
J. Mar. Sci. Eng. 2020, 8(11), 933; https://doi.org/10.3390/jmse8110933 - 17 Nov 2020
Viewed by 220
Abstract
In order to obtain a fair and reliable description of the wave amplitude and currents in harbors due to the tsunami generated by the 21 May 2003 Boumerdès earthquake (Algeria), a numerical investigation has been performed with a standard hydraulic numerical model combined [...] Read more.
In order to obtain a fair and reliable description of the wave amplitude and currents in harbors due to the tsunami generated by the 21 May 2003 Boumerdès earthquake (Algeria), a numerical investigation has been performed with a standard hydraulic numerical model combined with various source fault models. Seven different rupture models proposed in literature to represent high frequency seismic effects have been used to simulate tsunami generation. The tsunami wave propagation across the Western Mediterranean Sea and in bays and harbors of the Balearic Islands is simulated, and results are checked against sea level measurements. All of them resulted in a significant underestimation of the tsunami impact on the Balearic coasts. In the paper the best fitting source model is identified, justifying the energy intensification of the event to account for low frequency character of tsunami waves. A fair correspondence is pointed out between damages to boats and harbor infrastructures, reported in newspapers, and wave intensity, characterized by level extremes and current intensity. Current speed and amplitude thresholds for possible damage in harbors suggested respectively by Lynett et al., doi.org/10.1002/2013GL058680, and Muhari et al., doi.org/10.1007/s11069-015-1772-0, are confirmed by the present analysis. Full article
(This article belongs to the Special Issue Modelling of Harbour and Coastal Structures)
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Open AccessReview
The Wave Energy Converter Design Process: Methods Applied in Industry and Shortcomings of Current Practices
J. Mar. Sci. Eng. 2020, 8(11), 932; https://doi.org/10.3390/jmse8110932 - 17 Nov 2020
Viewed by 222
Abstract
Wave energy is among the many renewable energy technologies being researched and developed to address the increasing demand for low-emissions energy. The unique design challenges for wave energy converter design—integrating complex and uncertain technological, economic, and ecological systems, overcoming the structural challenges of [...] Read more.
Wave energy is among the many renewable energy technologies being researched and developed to address the increasing demand for low-emissions energy. The unique design challenges for wave energy converter design—integrating complex and uncertain technological, economic, and ecological systems, overcoming the structural challenges of ocean deployment, and dealing with complex system dynamics—have lead to a disjointed progression of research and development. There is no common design practice across the wave energy industry and there is no published synthesis of the practices that are used by developers. In this paper, we summarize the methods being employed in WEC design as well as promising methods that have yet to be applied. We contextualize these methods within an overarching design process. We present results from a survey of WEC developers to identify methods that are common in industry. From the review and survey results, we conclude that the most common methods of WEC design are iterative methods in which design parameters are defined, evaluated, and then changed based on evaluation results. This leaves a significant space for improvement of methods that help designers make better-informed decisions prior to sophisticated evaluation, and methods of using the evaluation results to make better design decisions during iteration. Despite the popularity of optimization methods in academic research, they are less common in industry development. We end this paper with a summary of the areas of WEC design in which the testing and development of new methods is necessary, and where more research is required to fully understand the influence of design decisions on WEC performance. Full article
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Open AccessArticle
Dynamics of the Land–Sea Breeze System and the Surface Current Response in South-West Australia
J. Mar. Sci. Eng. 2020, 8(11), 931; https://doi.org/10.3390/jmse8110931 - 17 Nov 2020
Viewed by 263
Abstract
The land–sea breeze (LSB) system, driven by the thermal contrast between the land and the adjacent ocean is a widely known atmospheric phenomenon, which occurs in coastal regions globally. South-west Australia experiences a persistent and one of the strongest LSB systems globally with [...] Read more.
The land–sea breeze (LSB) system, driven by the thermal contrast between the land and the adjacent ocean is a widely known atmospheric phenomenon, which occurs in coastal regions globally. South-west Australia experiences a persistent and one of the strongest LSB systems globally with maximum wind speeds associated with the LSB system often exceeding 15 ms−1. In this paper, using field measurements and numerical simulations, we examine: (1) the local winds associated with the land–sea breeze with an emphasis on the ocean; and, (2) the response of the surface currents to the diurnal wind forcing. The measurements indicated that the wind speeds decreased between midnight and 0400 and increased rapidly after 1100, reaching maxima >10 ms−1 around 1800) associated with the sea breeze and decreased to midnight. Wind directions were such that they were blowing from south-east (120°) in the morning and changed to almost southerly (~200°) in the afternoon. Decomposition of the wind record to the diurnal and synoptic components indicated that the diurnal component of winds (i.e., LSB) was oriented along the south-west to north-east axis. However, the stronger synoptic winds were from the south-east to south quadrant and in combination with the LSB, the winds consisted of a strong southerly component. We examined the evolution, horizontal extent, and propagation properties of sea breeze fronts for characteristic LSB cycles and the sea breeze cell propagating offshore and inland. The results indicated that the sea breeze cell was initiated in the morning in a small area, close to 33° S, 115.5° E, with a width of ~25 km and expanded onshore, offshore and alongshore. The sea breeze cell expanded faster (30 kmh−1) and farther (120 km) in the offshore direction than in the onshore direction (10 kmh−1 and 30–40 km). Winds during the LSB cycle followed a counterclockwise rotation that was also reflected in the surface currents. The winds and surface currents rotated anticlockwise with the surface currents responding almost instantaneously to changes in wind forcing but were modified by topography. The diurnal surface currents were enhanced due to the resonance between the LSB forcing and the inertial response. Full article
(This article belongs to the Section Physical Oceanography)
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Open AccessArticle
Interaction Effect between Hull and Accommodation on Wind Drag Acting on a Container Ship
J. Mar. Sci. Eng. 2020, 8(11), 930; https://doi.org/10.3390/jmse8110930 - 16 Nov 2020
Viewed by 227
Abstract
In this paper, we present our research on applying the commercial Computational Fluid Dynamics (CFD) code to investigate interaction effect between hull and accommodation on wind drag acting above the water hull surface of a full scale 1200 TEU container ship. With this [...] Read more.
In this paper, we present our research on applying the commercial Computational Fluid Dynamics (CFD) code to investigate interaction effect between hull and accommodation on wind drag acting above the water hull surface of a full scale 1200 TEU container ship. With this purpose, aerodynamic performances and wind drag acting on the ship hull with and without accommodations have been computed. Analyzing the obtained CFD results, the interaction effect between hull and accommodation on aerodynamic performances and wind drag acting on the ship have been found. Various new accommodation shapes have been proposed for the original ship to reduce the interaction effect on wind drag. A drastic reduction in the interaction effect between hull and accommodation on wind drag acting on the ship has been achieved and the obtained results have been shown in this paper. Full article
(This article belongs to the Special Issue CFD Simulations of Marine Hydrodynamics)
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Open AccessArticle
A Simplified Numerical Method for the Design and Analysis of FPSO Platform Brackets Subjected to Operational Conditions
J. Mar. Sci. Eng. 2020, 8(11), 929; https://doi.org/10.3390/jmse8110929 - 16 Nov 2020
Viewed by 254
Abstract
The present work develops a simplified computational methodology to predict brackets’ mechanical behavior to support mooring systems’ fairleads under maximum environmental loads. The methodology consists of estimating environmental loads in Campos’s basin (Brazil) using standards available in the literature and applying them to [...] Read more.
The present work develops a simplified computational methodology to predict brackets’ mechanical behavior to support mooring systems’ fairleads under maximum environmental loads. The methodology consists of estimating environmental loads in Campos’s basin (Brazil) using standards available in the literature and applying them to determine the stress distribution in the brackets’ solid domain using a code based on the Finite Element Method. The brackets studied here are composed of AH36 steel plates. Six different geometric configurations for the brackets considering thinner plates than those ordinarily employed in the existent brackets of the P-66 Petrobras oil production platform were studied. Theoretical recommendations about geometric configurations to reduce the von Mises maximum stress in brackets’ plates were determined in the light of constructal design. The results proved the importance of the geometric investigation in this problem. For instance, for the accidental limit state (ALS) the best configuration leads to a mechanical performance two times superior to that reached for the worst one, which had a maximum stress superior to the yielding limit. Moreover, the best designs for the superior and inferior brackets in the ALS have different configurations. Full article
(This article belongs to the Special Issue Mooring of Floating Offshore Structures)
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Open AccessArticle
Investigations of the Potential Application of k-out-of-n Systems in Oil and Gas Industry Objects
J. Mar. Sci. Eng. 2020, 8(11), 928; https://doi.org/10.3390/jmse8110928 - 16 Nov 2020
Viewed by 236
Abstract
The purpose of this paper was to demonstrate the possibilities of assessing the reliability of oil and gas industry structures with the help of mathematical models of k-out-of-n systems. We show how the reliability of various structures in the oil and [...] Read more.
The purpose of this paper was to demonstrate the possibilities of assessing the reliability of oil and gas industry structures with the help of mathematical models of k-out-of-n systems. We show how the reliability of various structures in the oil and gas complex can be described and investigated using k-out-of-n models. Because the initial information about the life and repair time of components of systems is only usually known on the scale of one and/or two moments, we focus on the problem of the sensitivity analysis of the system reliability indices to the shape of its components repair time distributions. To address this problem, we used the so-called markovization method, based on the introduction of supplementary variables, to model the system behavior with the help of the two-dimensional Markov process with discrete-continuous states. On the basis of the forward Kolmogorov equations for the time-dependent process’ state probabilities, relevant balance equations for the process’ stationary probabilities are presented. Using these equations, stationary probabilities and some reliability indices for two examples from the oil and gas industry were calculated and their sensitivity to the system component’s repair time distributions was analyzed. Calculations show that under “rare” component failures, most system reliability indices become practically insensitive to the shape of the components repair time distributions. Full article
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Open AccessArticle
A Fast Algorithm for the Prediction of Ship-Bank Interaction in Shallow Water
J. Mar. Sci. Eng. 2020, 8(11), 927; https://doi.org/10.3390/jmse8110927 - 16 Nov 2020
Viewed by 230
Abstract
The hydrodynamic interaction induced by the complex flow around a ship maneuvering in restricted waters has a significant influence on navigation safety. In particular, when a ship moves in the vicinity of a bank, the hydrodynamic interaction forces caused by the bank effect [...] Read more.
The hydrodynamic interaction induced by the complex flow around a ship maneuvering in restricted waters has a significant influence on navigation safety. In particular, when a ship moves in the vicinity of a bank, the hydrodynamic interaction forces caused by the bank effect can significantly affect the ship’s maneuverability. An efficient algorithm integrated in onboard systems or simulators for capturing the bank effect with fair accuracy would benefit navigation safety. In this study, an algorithm based on the potential-flow theory is presented for efficient calculation of ship-bank hydrodynamic interaction forces. Under the low Froude number assumption, the free surface boundary condition is approximated using the double-body model. A layer of sources is dynamically distributed on part of the seabed and bank in the vicinity of the ship to model the boundary conditions. The sinkage and trim are iteratively solved via hydrostatic balance, and the importance of including sinkage and trim is investigated. To validate the numerical method, a series of simulations with various configurations are carried out, and the results are compared with experiment and numerical results obtained with RANSE-based and Rankine source methods. The comparison and analysis show the accuracy of the method proposed in this paper satisfactory except for extreme shallow water cases. Full article
(This article belongs to the Section Coastal Engineering)
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Open AccessFeature PaperArticle
Thermal Stress Analysis of Process Piping System Installed on LNG Vessel Subject to Hull Design Loads
J. Mar. Sci. Eng. 2020, 8(11), 926; https://doi.org/10.3390/jmse8110926 - 16 Nov 2020
Viewed by 204
Abstract
In this paper, the procedure for the strength evaluation of the piping system installed on liquefied natural gas (LNG) carriers is discussed. A procedure that accounts for the ship’s wave load and hull motion acceleration (as well as the deformation due to the [...] Read more.
In this paper, the procedure for the strength evaluation of the piping system installed on liquefied natural gas (LNG) carriers is discussed. A procedure that accounts for the ship’s wave load and hull motion acceleration (as well as the deformation due to the thermal expansion and contraction experienced by the hull during seafaring operations) is presented. The load due to the temperature and self-weight of the piping installed on the deck is also considered. Various operating and load conditions of the LNG piping system are analyzed. Stress analysis is performed by combining various conditions of sustained, occasional, and expansion loads. Stress is assessed using finite element analysis based on beam elements that represent the behavior of the piping. The attributes of the piping system components (such as valves, expansion joints, and supports) are represented in the finite element model while CAESAR-II, a commercial software is used for finite element analysis. Component modeling, load assignment, and load combinations are presented to evaluate pipe stresses under various load conditions. An evaluation model is selected for the piping arrangement of LNG and the evaluated stress is compared with the allowable stress defined by the American Society of Mechanical Engineers (ASME). Full article
(This article belongs to the Special Issue Smart Technologies for Shipbuilding)
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