To ensure unmanned vehicles can perform a sortie mission quickly, efficiently, safely and reliably after receiving the command, it is necessary to calculate the sortie mission reliability of the shipborne unmanned vehicle group before loading. Aimed at the layout and sortie characteristics of an unmanned vehicle group, a sortie mission network model and a calculation method for sortie mission reliability are designed in this paper. Firstly, this paper uses space partition to parallel search for equal-length minimal paths based on the two-terminal network reliability. Secondly, this paper adopts the sum of disjoint products to process the equal-length minimal path set, innovatively proposing a calculation method for the sortie mission reliability of the shipborne unmanned vehicle group. Finally, the sortie mission reliability for three typical cases was calculated and compared with the Monte Carlo method. The comparative analysis indicates that the proposed method is both accurate and efficient, thereby corroborating its scientific validity and practical effectiveness. This study fills the gap in the field of sortie mission reliability and lays a theoretical foundation for subsequent research. Meanwhile, the method proposed in this paper can also be extended to the reliability calculation of a multiple-vehicle sortie mission in similar enclosed spaces.
{"title":"Calculation Method for Sortie Mission Reliability of Shipborne Unmanned Vehicle Group","authors":"Han Shi, Nengjian Wang, Qinhui Liu","doi":"10.3390/jmse12081309","DOIUrl":"https://doi.org/10.3390/jmse12081309","url":null,"abstract":"To ensure unmanned vehicles can perform a sortie mission quickly, efficiently, safely and reliably after receiving the command, it is necessary to calculate the sortie mission reliability of the shipborne unmanned vehicle group before loading. Aimed at the layout and sortie characteristics of an unmanned vehicle group, a sortie mission network model and a calculation method for sortie mission reliability are designed in this paper. Firstly, this paper uses space partition to parallel search for equal-length minimal paths based on the two-terminal network reliability. Secondly, this paper adopts the sum of disjoint products to process the equal-length minimal path set, innovatively proposing a calculation method for the sortie mission reliability of the shipborne unmanned vehicle group. Finally, the sortie mission reliability for three typical cases was calculated and compared with the Monte Carlo method. The comparative analysis indicates that the proposed method is both accurate and efficient, thereby corroborating its scientific validity and practical effectiveness. This study fills the gap in the field of sortie mission reliability and lays a theoretical foundation for subsequent research. Meanwhile, the method proposed in this paper can also be extended to the reliability calculation of a multiple-vehicle sortie mission in similar enclosed spaces.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The main purpose of this study is to set up a biogeochemistry model for the Ria de Aveiro ecosystem and evaluate the relative importance of the main parameters and the processes occurring at the interface between the water column and the upper layer of the bottom sediment. It addresses a gap in modeling the interactions between the biogeochemical status of the water column and the upper sediment layer in the Ria de Aveiro lagoon ecosystem. Traditional modeling studies treated the bottom sediment as a rigid boundary, ignoring significant biogeochemical interactions at the interface between the water column and the upper layer of the bottom sediment. Therefore, the model integrates, besides the main biogeochemical processes within the water column, those occurring at the upper benthic layer, focusing on nitrogen (N) and phosphorus (P) cycles. This approach aims to enhance the accuracy of model predictions and understanding of the Ria de Aveiro lagoon’s biogeochemical dynamics. The study will be focused on the following coupled state variables: TN/IN and TP/IP, for total and inorganic nitrogen (N) and total and inorganic phosphorus (P), respectively, where total stands for the sum of organic and inorganic components of those elements. The model was set up and validated for some water quality stations of the Ria de Aveiro. Analysis has identified key parameters influencing TN and TP, such as nitrification, denitrification rates, and oxygen penetration. TN was found sensitive to nitrate and ammonium diffusion coefficients, while TP was influenced by iron–phosphate interactions and phosphorus mineralization. Concerning the model validation, the results demonstrated that the RMSE and MAPE values for the main variables fall within an acceptable range, given the uncertainty related to data. The model was applied to assess the impact of the following physical forcing: river flow, water temperature, and salinity on N and P status of the water column. The results clearly demonstrate that bottom layer and water column interactions play an important role in the N and P status of the water column and contribute to the N and P concentration changes of the water. The influence of river flows alone led to contrasting behaviors among the lagoon stations, with significant increases in TP levels, which may be attributed to sediment release from the sediment layer. Nevertheless, the combination of high river flows and elevated nutrient levels at the river boundaries has led to significantly increased nitrogen (N) and phosphorus (P) levels, underscoring the influence of river flow on the interaction between bottom layer sediment and the water column. High water temperatures typically lead to an increase in total phosphorus (TP) levels, indicating a possible release from the sediment layer. Meanwhile, TN levels remained stable. Salinity changes had a minor impact compared to river flow and temperature. The study emphasizes the importance of understanding interactions be
{"title":"Assessing the Influence of the Benthic/Pelagic Exchange on the Nitrogen and Phosphorus Status of the Water Column, under Physical Forcings: A Modeling Study","authors":"José Fortes Lopes","doi":"10.3390/jmse12081310","DOIUrl":"https://doi.org/10.3390/jmse12081310","url":null,"abstract":"The main purpose of this study is to set up a biogeochemistry model for the Ria de Aveiro ecosystem and evaluate the relative importance of the main parameters and the processes occurring at the interface between the water column and the upper layer of the bottom sediment. It addresses a gap in modeling the interactions between the biogeochemical status of the water column and the upper sediment layer in the Ria de Aveiro lagoon ecosystem. Traditional modeling studies treated the bottom sediment as a rigid boundary, ignoring significant biogeochemical interactions at the interface between the water column and the upper layer of the bottom sediment. Therefore, the model integrates, besides the main biogeochemical processes within the water column, those occurring at the upper benthic layer, focusing on nitrogen (N) and phosphorus (P) cycles. This approach aims to enhance the accuracy of model predictions and understanding of the Ria de Aveiro lagoon’s biogeochemical dynamics. The study will be focused on the following coupled state variables: TN/IN and TP/IP, for total and inorganic nitrogen (N) and total and inorganic phosphorus (P), respectively, where total stands for the sum of organic and inorganic components of those elements. The model was set up and validated for some water quality stations of the Ria de Aveiro. Analysis has identified key parameters influencing TN and TP, such as nitrification, denitrification rates, and oxygen penetration. TN was found sensitive to nitrate and ammonium diffusion coefficients, while TP was influenced by iron–phosphate interactions and phosphorus mineralization. Concerning the model validation, the results demonstrated that the RMSE and MAPE values for the main variables fall within an acceptable range, given the uncertainty related to data. The model was applied to assess the impact of the following physical forcing: river flow, water temperature, and salinity on N and P status of the water column. The results clearly demonstrate that bottom layer and water column interactions play an important role in the N and P status of the water column and contribute to the N and P concentration changes of the water. The influence of river flows alone led to contrasting behaviors among the lagoon stations, with significant increases in TP levels, which may be attributed to sediment release from the sediment layer. Nevertheless, the combination of high river flows and elevated nutrient levels at the river boundaries has led to significantly increased nitrogen (N) and phosphorus (P) levels, underscoring the influence of river flow on the interaction between bottom layer sediment and the water column. High water temperatures typically lead to an increase in total phosphorus (TP) levels, indicating a possible release from the sediment layer. Meanwhile, TN levels remained stable. Salinity changes had a minor impact compared to river flow and temperature. The study emphasizes the importance of understanding interactions be","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
María Isabel Lamas Galdo, Juan de Dios Rodríguez García, Antonio Couce Casanova, Javier Blanco Damota, Claudio Giovanni Caccia, José Manuel Rebollido Lorenzo, Javier Telmo Miranda
Hydrokinetic energy constitutes a source of renewable energy. However, many regions have flow velocities that are too low for effective energy extraction, and conventional turbines are not suitable for these sites. In order to address this challenge, the present work proposes a novel vertical axis hydrokinetic turbine designed for environments where conventional turbines are not feasible due to a low water velocity. The turbine’s design is inspired by biological principles, enhancing the traditional Savonius turbine by incorporating a Fibonacci spiral-inspired blade configuration. The turbine’s performance was subjected to a rigorous analysis through Computational Fluid Dynamics (CFD). The results demonstrate a notable improvement, with a 15.1% increase in the power coefficient compared to the traditional Savonius turbine. This innovative approach not only extends the applicability of hydrokinetic turbines to low-flow regions but also underscores the potential of biomimicry in optimizing renewable energy technologies. The findings of this study indicate that integrating natural design principles can result in more efficient and sustainable energy solutions, thereby paving the way for the broader adoption of hydrokinetic power in diverse geographical settings.
{"title":"Enhanced Performance of a Hydrokinetic Turbine through a Biomimetic Design","authors":"María Isabel Lamas Galdo, Juan de Dios Rodríguez García, Antonio Couce Casanova, Javier Blanco Damota, Claudio Giovanni Caccia, José Manuel Rebollido Lorenzo, Javier Telmo Miranda","doi":"10.3390/jmse12081312","DOIUrl":"https://doi.org/10.3390/jmse12081312","url":null,"abstract":"Hydrokinetic energy constitutes a source of renewable energy. However, many regions have flow velocities that are too low for effective energy extraction, and conventional turbines are not suitable for these sites. In order to address this challenge, the present work proposes a novel vertical axis hydrokinetic turbine designed for environments where conventional turbines are not feasible due to a low water velocity. The turbine’s design is inspired by biological principles, enhancing the traditional Savonius turbine by incorporating a Fibonacci spiral-inspired blade configuration. The turbine’s performance was subjected to a rigorous analysis through Computational Fluid Dynamics (CFD). The results demonstrate a notable improvement, with a 15.1% increase in the power coefficient compared to the traditional Savonius turbine. This innovative approach not only extends the applicability of hydrokinetic turbines to low-flow regions but also underscores the potential of biomimicry in optimizing renewable energy technologies. The findings of this study indicate that integrating natural design principles can result in more efficient and sustainable energy solutions, thereby paving the way for the broader adoption of hydrokinetic power in diverse geographical settings.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ports play an important role in maintaining the effectiveness of maritime logistics. When ports encounter congestion, strikes, or natural disasters, the maritime container transportation network might be significantly affected. The Beibu Gulf sea area is a key channel to supporting China’s participation in international economic cooperation in the western region. It is highly susceptible to the influence of the political and economic instability. This study introduces a dual-component framework to analyze the inherent structure and potential vulnerabilities of the container transportation network in the Beibu Gulf Sea areas. The findings show that the core layer of the network exhibited circular solidification characteristics. The entire network heavily relies on some core ports, such as Haiphong Port, Ho Chi Minh Port, and Qinzhou Port, and it highlights the potential increases in vulnerability. The finding shows that deliberate attacks have a greater impact than random attacks on the normal operations of maritime networks. If ports with high intermediary centrality are attacked, the connectivity and transportation efficiency of the Beibu Gulf maritime network will be significantly affected. However, under such circumstances, redistributing cargo transportation through route adjustments can deal with the transmission of cascading failures and maintain the network’s resilience. Based on the existing knowledge and the data collected in a case study, this research stands out as the first to provide a critical examination of the spatial structure and vulnerability of container shipping networks in the Beibu Gulf sea.
{"title":"Spatial Structure and Vulnerability of Container Shipping Networks: A Case Study in the Beibu Gulf Sea Area","authors":"Mengyu Xia, Jinhai Chen, Pengfei Zhang, Peng Peng, Christophe Claramunt","doi":"10.3390/jmse12081307","DOIUrl":"https://doi.org/10.3390/jmse12081307","url":null,"abstract":"Ports play an important role in maintaining the effectiveness of maritime logistics. When ports encounter congestion, strikes, or natural disasters, the maritime container transportation network might be significantly affected. The Beibu Gulf sea area is a key channel to supporting China’s participation in international economic cooperation in the western region. It is highly susceptible to the influence of the political and economic instability. This study introduces a dual-component framework to analyze the inherent structure and potential vulnerabilities of the container transportation network in the Beibu Gulf Sea areas. The findings show that the core layer of the network exhibited circular solidification characteristics. The entire network heavily relies on some core ports, such as Haiphong Port, Ho Chi Minh Port, and Qinzhou Port, and it highlights the potential increases in vulnerability. The finding shows that deliberate attacks have a greater impact than random attacks on the normal operations of maritime networks. If ports with high intermediary centrality are attacked, the connectivity and transportation efficiency of the Beibu Gulf maritime network will be significantly affected. However, under such circumstances, redistributing cargo transportation through route adjustments can deal with the transmission of cascading failures and maintain the network’s resilience. Based on the existing knowledge and the data collected in a case study, this research stands out as the first to provide a critical examination of the spatial structure and vulnerability of container shipping networks in the Beibu Gulf sea.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Identifying and analyzing the engine performance and emission characteristics under the condition of performance decay is of significant reference value for fault diagnosis, condition-based maintenance, and health status monitoring. However, there is a lack of relevant research on the currently popular marine large two-stroke dual fuel (DF) engines. To fill the research gap, a detailed zero-/one-dimensional (0D/1D) model of a marine two-stroke DF engine employing the low-pressure gas concept is first established in GT-Power (Version 2020) and validated by comparing the simulation and measured results. Then, three typical types of turbocharger performance decays are defined including turbine efficiency decay, turbine nozzle ring area decay, and turbocharger shaft mechanical efficiency decay. Finally, the three types of decays are introduced to the engine simulation model and parametric runs are performed in both diesel and gas modes to identify and analyze their impacts on the performance and emission characteristics of the investigated marine DF engine. The results reveal that turbocharger performance decay has a significant impact on engine performance parameters, such as brake efficiency, engine speed, boost pressure, etc., as well as CO2 and NOx emissions, and the specified limit value on certain engine operational parameters will be exceeded when turbocharger performance decays to a certain extent. The changing trend of engine performance and emission parameters as turbocharger performance deteriorates are generally consistent in both operating modes but with significant differences in the extent and magnitude, mainly due to the distinct combustion process (Diesel cycle versus Otto cycle). Furthermore, considering the relative decline in brake efficiency, engine speed drop, and relative increase in CO2 emission, the investigated engine is less sensitive to the turbocharger performance decay in gas mode. The simulation results also imply that employing a variable geometry turbine (VGT) is capable of improving the brake efficiency of the investigated marine DF engine.
{"title":"Parametric Investigation on the Influence of Turbocharger Performance Decay on the Performance and Emission Characteristics of a Marine Large Two-Stroke Dual Fuel Engine","authors":"Haosheng Shen, Fumiao Yang, Dingyu Jiang, Daoyi Lu, Baozhu Jia, Qingjiang Liu, Xiaochi Zhang","doi":"10.3390/jmse12081298","DOIUrl":"https://doi.org/10.3390/jmse12081298","url":null,"abstract":"Identifying and analyzing the engine performance and emission characteristics under the condition of performance decay is of significant reference value for fault diagnosis, condition-based maintenance, and health status monitoring. However, there is a lack of relevant research on the currently popular marine large two-stroke dual fuel (DF) engines. To fill the research gap, a detailed zero-/one-dimensional (0D/1D) model of a marine two-stroke DF engine employing the low-pressure gas concept is first established in GT-Power (Version 2020) and validated by comparing the simulation and measured results. Then, three typical types of turbocharger performance decays are defined including turbine efficiency decay, turbine nozzle ring area decay, and turbocharger shaft mechanical efficiency decay. Finally, the three types of decays are introduced to the engine simulation model and parametric runs are performed in both diesel and gas modes to identify and analyze their impacts on the performance and emission characteristics of the investigated marine DF engine. The results reveal that turbocharger performance decay has a significant impact on engine performance parameters, such as brake efficiency, engine speed, boost pressure, etc., as well as CO2 and NOx emissions, and the specified limit value on certain engine operational parameters will be exceeded when turbocharger performance decays to a certain extent. The changing trend of engine performance and emission parameters as turbocharger performance deteriorates are generally consistent in both operating modes but with significant differences in the extent and magnitude, mainly due to the distinct combustion process (Diesel cycle versus Otto cycle). Furthermore, considering the relative decline in brake efficiency, engine speed drop, and relative increase in CO2 emission, the investigated engine is less sensitive to the turbocharger performance decay in gas mode. The simulation results also imply that employing a variable geometry turbine (VGT) is capable of improving the brake efficiency of the investigated marine DF engine.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liner shipping accounts for over 80% of the global transportation volume, making substantial contributions to world trade and economic development. To advance global economic integration further, it is essential to link the flows of global liner shipping routes with the complex system of international trade, thereby supporting liner shipping as an effective framework for analyzing international trade and geopolitical trends. Traditional methods based on first-order global liner shipping networks, operating at a single scale, lack sufficient descriptive power for multi-variable sequential interactions and data representation accuracy among nodes. This paper proposes an effective methodology termed “Multi-Scale Higher-Order Dependencies (MSHOD)” that adeptly reveals the complexity of higher-order interactions among multi-scale nodes within the global liner shipping network. The key step of this method is to construct high-order dependency networks through multi-scale attributes. Based on the critical role of high-order interactions, a method for key node identification has been proposed. Experiments demonstrate that, compared to other methods, MSHOD can more effectively identify multi-scale nodes with regional dependencies. These nodes and their generated higher-order interactions could have transformative impacts on the network’s flow and stability. Therefore, by integrating multi-scale analysis methods to mine high-order interactions and identify key nodes with regional dependencies, this approach provides robust insights for assessing policy implementation effects, preventing unforeseen incidents, and revealing regional dual-circulation economic models, thereby contributing to strategies for global, stable development.
{"title":"Multi-Scale Higher-Order Dependencies (MSHOD): Higher-Order Interactions Mining and Key Nodes Identification for Global Liner Shipping Network","authors":"Yude Fu, Xiang Li, Jichao Li, Mengjun Yu, Xiongyi Lu, Qizi Huangpeng, Xiaojun Duan","doi":"10.3390/jmse12081305","DOIUrl":"https://doi.org/10.3390/jmse12081305","url":null,"abstract":"Liner shipping accounts for over 80% of the global transportation volume, making substantial contributions to world trade and economic development. To advance global economic integration further, it is essential to link the flows of global liner shipping routes with the complex system of international trade, thereby supporting liner shipping as an effective framework for analyzing international trade and geopolitical trends. Traditional methods based on first-order global liner shipping networks, operating at a single scale, lack sufficient descriptive power for multi-variable sequential interactions and data representation accuracy among nodes. This paper proposes an effective methodology termed “Multi-Scale Higher-Order Dependencies (MSHOD)” that adeptly reveals the complexity of higher-order interactions among multi-scale nodes within the global liner shipping network. The key step of this method is to construct high-order dependency networks through multi-scale attributes. Based on the critical role of high-order interactions, a method for key node identification has been proposed. Experiments demonstrate that, compared to other methods, MSHOD can more effectively identify multi-scale nodes with regional dependencies. These nodes and their generated higher-order interactions could have transformative impacts on the network’s flow and stability. Therefore, by integrating multi-scale analysis methods to mine high-order interactions and identify key nodes with regional dependencies, this approach provides robust insights for assessing policy implementation effects, preventing unforeseen incidents, and revealing regional dual-circulation economic models, thereby contributing to strategies for global, stable development.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electric motors are indispensable electrical equipment in ships, with a wide range of applications. They can serve as auxiliary devices for propulsion, such as air compressors, anchor winches, and pumps, and are also used in propulsion systems; ensuring the safe and reliable operation of motors is crucial for ships. Existing deep learning methods typically target motors under a specific operating state and are susceptible to noise during feature extraction. To address these issues, this paper proposes a Resformer model based on bimodal input. First, vibration signals are transformed into time–frequency diagrams using continuous wavelet transform (CWT), and three-phase current signals are converted into Park vector modulus (PVM) signals through Park transformation. The time–frequency diagrams and PVM signals are then aligned in the time sequence to be used as bimodal input samples. The analysis of time–frequency images and PVM signals indicates that the same fault condition under different loads but at the same speed exhibits certain similarities. Therefore, data from the same fault condition under different loads but at the same speed are combined for cross-domain motor fault diagnosis. The proposed Resformer model combines the powerful spatial feature extraction capabilities of the Swin-t model with the excellent fine feature extraction and efficient training performance of the ResNet model. Experimental results show that the Resformer model can effectively diagnose cross-domain motor faults and maintains performance even under different noise conditions. Compared with single-modal models (VGG-11, ResNet, ResNeXt, and Swin-t), dual-modal models (MLP-Transformer and LSTM-Transformer), and other large models (Swin-s, Swin-b, and VGG-19), the Resformer model exhibits superior overall performance. This validates the method’s effectiveness and accuracy in the intelligent recognition of common cross-domain motor faults.
{"title":"A New Cross-Domain Motor Fault Diagnosis Method Based on Bimodal Inputs","authors":"Qianming Shang, Tianyao Jin, Mingsheng Chen","doi":"10.3390/jmse12081304","DOIUrl":"https://doi.org/10.3390/jmse12081304","url":null,"abstract":"Electric motors are indispensable electrical equipment in ships, with a wide range of applications. They can serve as auxiliary devices for propulsion, such as air compressors, anchor winches, and pumps, and are also used in propulsion systems; ensuring the safe and reliable operation of motors is crucial for ships. Existing deep learning methods typically target motors under a specific operating state and are susceptible to noise during feature extraction. To address these issues, this paper proposes a Resformer model based on bimodal input. First, vibration signals are transformed into time–frequency diagrams using continuous wavelet transform (CWT), and three-phase current signals are converted into Park vector modulus (PVM) signals through Park transformation. The time–frequency diagrams and PVM signals are then aligned in the time sequence to be used as bimodal input samples. The analysis of time–frequency images and PVM signals indicates that the same fault condition under different loads but at the same speed exhibits certain similarities. Therefore, data from the same fault condition under different loads but at the same speed are combined for cross-domain motor fault diagnosis. The proposed Resformer model combines the powerful spatial feature extraction capabilities of the Swin-t model with the excellent fine feature extraction and efficient training performance of the ResNet model. Experimental results show that the Resformer model can effectively diagnose cross-domain motor faults and maintains performance even under different noise conditions. Compared with single-modal models (VGG-11, ResNet, ResNeXt, and Swin-t), dual-modal models (MLP-Transformer and LSTM-Transformer), and other large models (Swin-s, Swin-b, and VGG-19), the Resformer model exhibits superior overall performance. This validates the method’s effectiveness and accuracy in the intelligent recognition of common cross-domain motor faults.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research explored the influence of seasonal and environmental variables on the variation and density of ichthyoplankton in the Thermaikos Gulf and the adjacent marine protected area of the Litochoro artificial reef in Pieria, northern Greece. The objective was to assess the condition of existing ichthyoplankton communities, understand their relationship with seasonal environmental parameters, and ascertain whether the area plays the role of a fish nursery site. Observations were carried out on the boundary of the marine protected area near Litochoro, with collection sessions occurring during the spring, summer, and fall seasons from 2018 to 2021. Ichthyoplankton was collected using a bongo net sampler across 16 stations, identifying seventy larval fish species. Measurements of physico-chemical parameters were taken as well as community and population metrics such as species abundances. In the Litochoro area, the interplay between environmental conditions and the dynamics of ichthyoplankton species highlights significant ecological trends. Notably, commercially important species such as Engraulis encrasicholus (anchovy) and Sardina pilchardus (sardine) exhibited peaks in abundances, with anchovies reaching up to 544/10 m2 in May 2021 and sardines peaking at 383/10 m2 in April 2020. These species are crucial both ecologically, as integral components of the marine food web, and economically, serving as primary targets in local fisheries. Spearman analysis showed some species like anchovy having a negative trend with chl-a values. Also, diversity indices had strong negative correlations with chl-a values, suggesting that higher chl-a concentrations might be associated with lower biodiversity whereas most diversity indices, apart from Pielou’s normality index (J) and Simpson’s diversity index (1–lambda), showed a significant positive correlation with surface salinity. This suggests that increased salinity levels might boost certain facets of biodiversity during the summer and early autumn months.
{"title":"Seasonal Shifts: Tracking Fish Larval Diversity in a Coastal Marine Protected Area","authors":"Athanasios A. Kallianiotis, Nikolaos Kamidis","doi":"10.3390/jmse12081300","DOIUrl":"https://doi.org/10.3390/jmse12081300","url":null,"abstract":"This research explored the influence of seasonal and environmental variables on the variation and density of ichthyoplankton in the Thermaikos Gulf and the adjacent marine protected area of the Litochoro artificial reef in Pieria, northern Greece. The objective was to assess the condition of existing ichthyoplankton communities, understand their relationship with seasonal environmental parameters, and ascertain whether the area plays the role of a fish nursery site. Observations were carried out on the boundary of the marine protected area near Litochoro, with collection sessions occurring during the spring, summer, and fall seasons from 2018 to 2021. Ichthyoplankton was collected using a bongo net sampler across 16 stations, identifying seventy larval fish species. Measurements of physico-chemical parameters were taken as well as community and population metrics such as species abundances. In the Litochoro area, the interplay between environmental conditions and the dynamics of ichthyoplankton species highlights significant ecological trends. Notably, commercially important species such as Engraulis encrasicholus (anchovy) and Sardina pilchardus (sardine) exhibited peaks in abundances, with anchovies reaching up to 544/10 m2 in May 2021 and sardines peaking at 383/10 m2 in April 2020. These species are crucial both ecologically, as integral components of the marine food web, and economically, serving as primary targets in local fisheries. Spearman analysis showed some species like anchovy having a negative trend with chl-a values. Also, diversity indices had strong negative correlations with chl-a values, suggesting that higher chl-a concentrations might be associated with lower biodiversity whereas most diversity indices, apart from Pielou’s normality index (J) and Simpson’s diversity index (1–lambda), showed a significant positive correlation with surface salinity. This suggests that increased salinity levels might boost certain facets of biodiversity during the summer and early autumn months.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Over the past decade, the renewable energy sector has witnessed remarkable growth, which has been attributed to government support [...]
在过去十年中，可再生能源部门取得了显著增长，这归功于政府的支持 [...]
{"title":"Optimization and Energy Maximizing Control Systems for Wave Energy Converters II","authors":"Giuseppe Giorgi, Mauro Bonfanti","doi":"10.3390/jmse12081297","DOIUrl":"https://doi.org/10.3390/jmse12081297","url":null,"abstract":"Over the past decade, the renewable energy sector has witnessed remarkable growth, which has been attributed to government support [...]","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Igor Yaroshchuk, Valery Liapidevskii, Alexandra Kosheleva, Grigory Dolgikh, Alexander Pivovarov, Aleksandr Samchenko, Alex Shvyrev, Oleg Gulin, Roman Korotchenko, Fedor Khrapchenkov
This paper presents a discussion on observations of nonlinear internal waves (NLIWs) in the coastal zone of the Sea of Japan, based on the mooring of thermostring clusters in different seasons of 2022. For statistical evaluation of the frequency of event occurrence and determination of NLIW movement direction, we use our observations of the past 12 years. We present the NLIW structures, observed in spring, summer, and autumn of 2022, which are typical for this shelf area. Two types of nonlinear waves are described—solitary and undular bores, with or without strong vertical mixing behind the front. We demonstrate spatial transformation of an undular bore as it moves over the shelf. A mathematical model based on the second-order shallow water approximation is proposed for numerical simulation. To simplify calculations, the authors limit themselves to two- and three-layer shallow water models. We investigate the possibility of spatiotemporal reconstruction of internal nonlinear structures between thermostrings using experimental data and proposed models. The authors show that at distances of up to several kilometers between thermostrings, the wave fields of strongly nonlinear and nonstationary structures can be successfully reconstructed. Water flow induced by NLIWs can be reconstructed from the data of even one thermostring.
{"title":"Observation and Modeling of Nonlinear Internal Waves on the Sea of Japan Shelf","authors":"Igor Yaroshchuk, Valery Liapidevskii, Alexandra Kosheleva, Grigory Dolgikh, Alexander Pivovarov, Aleksandr Samchenko, Alex Shvyrev, Oleg Gulin, Roman Korotchenko, Fedor Khrapchenkov","doi":"10.3390/jmse12081301","DOIUrl":"https://doi.org/10.3390/jmse12081301","url":null,"abstract":"This paper presents a discussion on observations of nonlinear internal waves (NLIWs) in the coastal zone of the Sea of Japan, based on the mooring of thermostring clusters in different seasons of 2022. For statistical evaluation of the frequency of event occurrence and determination of NLIW movement direction, we use our observations of the past 12 years. We present the NLIW structures, observed in spring, summer, and autumn of 2022, which are typical for this shelf area. Two types of nonlinear waves are described—solitary and undular bores, with or without strong vertical mixing behind the front. We demonstrate spatial transformation of an undular bore as it moves over the shelf. A mathematical model based on the second-order shallow water approximation is proposed for numerical simulation. To simplify calculations, the authors limit themselves to two- and three-layer shallow water models. We investigate the possibility of spatiotemporal reconstruction of internal nonlinear structures between thermostrings using experimental data and proposed models. The authors show that at distances of up to several kilometers between thermostrings, the wave fields of strongly nonlinear and nonstationary structures can be successfully reconstructed. Water flow induced by NLIWs can be reconstructed from the data of even one thermostring.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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