This study presents a comprehensive approach to trim optimization as an energy efficiency improvement measure, focusing on reducing fuel consumption for one RO-RO car carrier. Utilizing Computational Fluid Dynamics (CFD) software, the methodology incorporates artificial neural networks (ANNs) to develop a mathematical model for estimating key parameters such as the brake power, daily fuel oil consumption (DFOC) and propeller speed. The complex ANN model is then integrated into a user-friendly software tool for practical engineering applications. The research outlines a seven-phase trim optimization process and discusses its potential extension to other types of ships, aiming to establish a universal methodology for CFD-based engineering analyses. Based on the trim optimization results, the biggest DFOC goes up to 10.5% at 7.5 m draft and up to 8% for higher drafts. Generally, in every considered case, it is recommended to sail with the trim towards the bow, meaning that the ship’s longitudinal center of gravity should be adjusted to tilt slightly forward.
{"title":"CFD-Powered Ship Trim Optimization: Integrating ANN for User-Friendly Software Tool Development","authors":"Matija Vasilev, Milan Kalajdžić, Ines Ivković","doi":"10.3390/jmse12081265","DOIUrl":"https://doi.org/10.3390/jmse12081265","url":null,"abstract":"This study presents a comprehensive approach to trim optimization as an energy efficiency improvement measure, focusing on reducing fuel consumption for one RO-RO car carrier. Utilizing Computational Fluid Dynamics (CFD) software, the methodology incorporates artificial neural networks (ANNs) to develop a mathematical model for estimating key parameters such as the brake power, daily fuel oil consumption (DFOC) and propeller speed. The complex ANN model is then integrated into a user-friendly software tool for practical engineering applications. The research outlines a seven-phase trim optimization process and discusses its potential extension to other types of ships, aiming to establish a universal methodology for CFD-based engineering analyses. Based on the trim optimization results, the biggest DFOC goes up to 10.5% at 7.5 m draft and up to 8% for higher drafts. Generally, in every considered case, it is recommended to sail with the trim towards the bow, meaning that the ship’s longitudinal center of gravity should be adjusted to tilt slightly forward.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778773","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}
To analyze the dynamic response of a rigid M-shaped jumper subjected to combined internal and external flows, a one-way coupled fluid–structure interaction process is applied. First, CFD simulations are conducted separately for the internal and external fluid domains. The pressure histories on the inner and outer walls are exported and loaded into the finite element model using inverse distance interpolation. Then, FEA is performed to determine the dynamic response, followed by a fatigue assessment based on the obtained stress data. The displacement, acceleration, and stress distribution along the M-shaped jumper are obtained. External flow velocity dominates the displacements, while internal flow velocity dominates the vibrations and stresses. The structural response to the combined effect of internal and external flows, plus the response to gravity alone, equals the sum of the structural responses to internal flow alone and external flow alone. Fatigue damage is calculated for the bend exhibiting the most intense vibration and higher stress levels, and the locations with significant damage correspond to areas with high maximum von Mises stress. This paper aims to evaluate multiple flow fields acting simultaneously on subsea pipelines and to identify the main factors that provide valuable information for their design, monitoring, and maintenance.
为了分析刚性 M 型跳线在内部和外部气流共同作用下的动态响应，采用了单向耦合流固耦合过程。首先，分别对内部和外部流体域进行 CFD 模拟。使用反距离插值法将内外壁上的压力历史导出并加载到有限元模型中。然后，进行有限元分析以确定动态响应，并根据获得的应力数据进行疲劳评估。结果得出了沿 M 型跳线的位移、加速度和应力分布。外部流速主导位移，而内部流速主导振动和应力。结构对内部和外部水流共同作用的响应，加上对重力单独作用的响应，等于结构对内部水流单独作用和外部水流单独作用的响应之和。对振动最剧烈、应力水平较高的弯道进行疲劳损伤计算，损伤严重的位置与最大 von Mises 应力较高的区域相对应。本文旨在评估同时作用于海底管道的多个流场，并确定可为管道设计、监测和维护提供有价值信息的主要因素。
{"title":"Dynamic Response Analysis of a Subsea Rigid M-Shaped Jumper under Combined Internal and External Flows","authors":"Guangzhao Li, Wenhua Li, Shanying Lin, Fenghui Han, Xingkun Zhou","doi":"10.3390/jmse12081261","DOIUrl":"https://doi.org/10.3390/jmse12081261","url":null,"abstract":"To analyze the dynamic response of a rigid M-shaped jumper subjected to combined internal and external flows, a one-way coupled fluid–structure interaction process is applied. First, CFD simulations are conducted separately for the internal and external fluid domains. The pressure histories on the inner and outer walls are exported and loaded into the finite element model using inverse distance interpolation. Then, FEA is performed to determine the dynamic response, followed by a fatigue assessment based on the obtained stress data. The displacement, acceleration, and stress distribution along the M-shaped jumper are obtained. External flow velocity dominates the displacements, while internal flow velocity dominates the vibrations and stresses. The structural response to the combined effect of internal and external flows, plus the response to gravity alone, equals the sum of the structural responses to internal flow alone and external flow alone. Fatigue damage is calculated for the bend exhibiting the most intense vibration and higher stress levels, and the locations with significant damage correspond to areas with high maximum von Mises stress. This paper aims to evaluate multiple flow fields acting simultaneously on subsea pipelines and to identify the main factors that provide valuable information for their design, monitoring, and maintenance.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778775","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}
Guolei Huang, Yifan Liu, Jianjian Xin, Tiantian Bao
Evaluating the degradation of hull and ship performance and exploring their degradation pathways is crucial for developing scientific and reasonable ship maintenance plans. This paper proposes a two-stage optimization (TSO) algorithm that combines the Genetic Algorithm (GA) and Long Short-Term Memory (LSTM) network, capable of simultaneously optimizing input features and model parameters to enhance the accuracy and generalization ability of speed prediction models. Additionally, a performance degradation assessment method based on speed loss is provided, aimed at evaluating the degradation of hull and propeller performance, as well as extracting the performance degradation paths. The results indicated that the proposed TSO-LSTM-GA algorithm significantly outperformed existing baseline models. Furthermore, the provided performance degradation assessment method demonstrated certain effectiveness on the target ship data, with a measured degradation rate of 0.00344 kn/d and a performance degradation of 9.569% over 478 days, corresponding to an annual speed loss of 1.257 kn.
{"title":"Assessment of Hull and Propeller Performance Degradation Based on TSO-GA-LSTM","authors":"Guolei Huang, Yifan Liu, Jianjian Xin, Tiantian Bao","doi":"10.3390/jmse12081263","DOIUrl":"https://doi.org/10.3390/jmse12081263","url":null,"abstract":"Evaluating the degradation of hull and ship performance and exploring their degradation pathways is crucial for developing scientific and reasonable ship maintenance plans. This paper proposes a two-stage optimization (TSO) algorithm that combines the Genetic Algorithm (GA) and Long Short-Term Memory (LSTM) network, capable of simultaneously optimizing input features and model parameters to enhance the accuracy and generalization ability of speed prediction models. Additionally, a performance degradation assessment method based on speed loss is provided, aimed at evaluating the degradation of hull and propeller performance, as well as extracting the performance degradation paths. The results indicated that the proposed TSO-LSTM-GA algorithm significantly outperformed existing baseline models. Furthermore, the provided performance degradation assessment method demonstrated certain effectiveness on the target ship data, with a measured degradation rate of 0.00344 kn/d and a performance degradation of 9.569% over 478 days, corresponding to an annual speed loss of 1.257 kn.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778780","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 mechanical response of the marine reef sand–geogrid (RG) interface can be influenced by a high-temperature climate, grain size, and variable stress environments. These factors are critical to the effectiveness of geogrid reinforcement in reef sand engineering. However, there are few studies on the influences of grain size, temperature, and stress history on the mechanical characteristics of RG interfaces, with most studies centering on the influence of single factors on the mechanical characteristics of RG interfaces. In this paper, based on self-developed temperature-controlled large interface shear equipment, a series of before/post-cyclic shear tests were carried out on RG interfaces in the temperature range of 5–80 °C. The impact of different reef sand grain sizes on the RG interface was explored (S1: 1–2 mm; S2: 2–4 mm). It was shown that temperature and grain size had significant influences on the mechanical characteristics of the RS interface. Compared with the S1 RG interfaces, the S2 RG interfaces had higher sensitivity to temperature changes with respect to the before/post-cyclic maximum shear strength. Moreover, in comparison to the before-cyclic shear strength, the post-cyclic maximum shear strength is more responsive to temperature changes. The before/post-cyclic maximum shear strength of the S2 RG interfaces was greater than the maximum shear strength of the S1 RG interfaces as the temperature changed. Based on the results of physical tests, a machine learning model containing 450 datasets was constructed, which can accurately predict the shear strength of the RG interface.
{"title":"Temperature-Dependent Post-Cyclic Mechanical Characteristics of Interfaces between Geogrid and Marine Reef Sand: Experimental Research and Machine Learning Modeling","authors":"Zhiming Chao, Haoyu Wang, Jinhai Zheng, Danda Shi, Chunxu Li, Gege Ding, Xianhui Feng","doi":"10.3390/jmse12081262","DOIUrl":"https://doi.org/10.3390/jmse12081262","url":null,"abstract":"The mechanical response of the marine reef sand–geogrid (RG) interface can be influenced by a high-temperature climate, grain size, and variable stress environments. These factors are critical to the effectiveness of geogrid reinforcement in reef sand engineering. However, there are few studies on the influences of grain size, temperature, and stress history on the mechanical characteristics of RG interfaces, with most studies centering on the influence of single factors on the mechanical characteristics of RG interfaces. In this paper, based on self-developed temperature-controlled large interface shear equipment, a series of before/post-cyclic shear tests were carried out on RG interfaces in the temperature range of 5–80 °C. The impact of different reef sand grain sizes on the RG interface was explored (S1: 1–2 mm; S2: 2–4 mm). It was shown that temperature and grain size had significant influences on the mechanical characteristics of the RS interface. Compared with the S1 RG interfaces, the S2 RG interfaces had higher sensitivity to temperature changes with respect to the before/post-cyclic maximum shear strength. Moreover, in comparison to the before-cyclic shear strength, the post-cyclic maximum shear strength is more responsive to temperature changes. The before/post-cyclic maximum shear strength of the S2 RG interfaces was greater than the maximum shear strength of the S1 RG interfaces as the temperature changed. Based on the results of physical tests, a machine learning model containing 450 datasets was constructed, which can accurately predict the shear strength of the RG interface.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778776","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}
Freak waves are characterized by extreme wave height, irregular wave shape, high peak energy, short duration, and formidable destructive potential, posing a significant threat to offshore structures. Therefore, analyzing dynamic responses exhibited by advanced offshore platforms such as the offshore triceratops under the influence of freak waves holds paramount importance. However, the response analysis of offshore triceratops under freak waves has not been explored so far in the literature. Hence, the present study aims to investigate the dynamics of offshore triceratops intended for ultradeep waters under the impact of freak waves. Initially, the dual superposition model was utilized to generate the freak waves, and the numerical model of the platform was developed using ANSYS AQWA. Subsequently, the dynamic response characteristics of offshore triceratops under the influence of freak waves were analyzed in the time domain. The results demonstrate the effects of freak waves on the surge, heave, and pitch responses of the deck and buoyant legs were substantial, leading to a significant increase in maximum responses and variations in mean shift and standard deviations. The innovative insights derived from this study can serve as a benchmark for validating the effective performance and design of offshore triceratops.
{"title":"Study on the Dynamic Response of Offshore Triceratops under Freak Waves","authors":"Nagavinothini Ravichandran, Butsawan Bidorn","doi":"10.3390/jmse12081260","DOIUrl":"https://doi.org/10.3390/jmse12081260","url":null,"abstract":"Freak waves are characterized by extreme wave height, irregular wave shape, high peak energy, short duration, and formidable destructive potential, posing a significant threat to offshore structures. Therefore, analyzing dynamic responses exhibited by advanced offshore platforms such as the offshore triceratops under the influence of freak waves holds paramount importance. However, the response analysis of offshore triceratops under freak waves has not been explored so far in the literature. Hence, the present study aims to investigate the dynamics of offshore triceratops intended for ultradeep waters under the impact of freak waves. Initially, the dual superposition model was utilized to generate the freak waves, and the numerical model of the platform was developed using ANSYS AQWA. Subsequently, the dynamic response characteristics of offshore triceratops under the influence of freak waves were analyzed in the time domain. The results demonstrate the effects of freak waves on the surge, heave, and pitch responses of the deck and buoyant legs were substantial, leading to a significant increase in maximum responses and variations in mean shift and standard deviations. The innovative insights derived from this study can serve as a benchmark for validating the effective performance and design of offshore triceratops.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778774","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}
Due to the detrimental impact of fog on image quality, dehazing maritime images is essential for applications such as safe maritime navigation, surveillance, environmental monitoring, and marine research. Traditional dehazing techniques, which are dependent on presupposed conditions, often fail to perform effectively, particularly when processing sky regions within marine fog images in which these conditions are not met. This study proposes an adaptive sky area segmentation dark channel prior to the marine image dehazing method. This study effectively addresses challenges associated with traditional marine image dehazing methods, improving dehazing results affected by bright targets in the sky area and mitigating the grayish appearance caused by the dark channel. This study uses the grayscale value of the region boundary’s grayscale discontinuity characteristics, takes the grayscale value with the least number of discontinuity areas in the grayscale histogram as a segmentation threshold adapted to the characteristics of the sea fog image to segment bright areas such as the sky, and then uses grayscale gradients to identify grayscale differences in different bright areas, accurately distinguishing boundaries between sky and non-sky areas. By comparing the area parameters, non-sky blocks are filled; this adaptively eliminates interference from other bright non-sky areas and accurately locks the sky area. Furthermore, this study proposes an enhanced dark channel prior approach that optimizes transmittance locally within sky areas and globally across the image. This is achieved using a transmittance optimization algorithm combined with guided filtering technology. The atmospheric light estimation is refined through iterative adjustments, ensuring consistency in brightness between the dehazed and original images. The image reconstruction employs calculated atmospheric light and transmittance values through an atmospheric scattering model. Finally, the use of gamma-correction technology ensures that images more accurately replicate natural colors and brightness levels. Experimental outcomes demonstrate substantial improvements in the contrast, color saturation, and visual clarity of marine fog images. Additionally, a set of foggy marine image data sets is developed for monitoring purposes. Compared with traditional dark channel prior dehazing techniques, this new approach significantly improves fog removal. This advancement enhances the clarity of images obtained from maritime equipment and effectively mitigates the risk of maritime transportation accidents.
{"title":"A Method for Defogging Sea Fog Images by Integrating Dark Channel Prior with Adaptive Sky Region Segmentation","authors":"Kongchi Hu, Qingyan Zeng, Junyan Wang, Jianqing Huang, Qi Yuan","doi":"10.3390/jmse12081255","DOIUrl":"https://doi.org/10.3390/jmse12081255","url":null,"abstract":"Due to the detrimental impact of fog on image quality, dehazing maritime images is essential for applications such as safe maritime navigation, surveillance, environmental monitoring, and marine research. Traditional dehazing techniques, which are dependent on presupposed conditions, often fail to perform effectively, particularly when processing sky regions within marine fog images in which these conditions are not met. This study proposes an adaptive sky area segmentation dark channel prior to the marine image dehazing method. This study effectively addresses challenges associated with traditional marine image dehazing methods, improving dehazing results affected by bright targets in the sky area and mitigating the grayish appearance caused by the dark channel. This study uses the grayscale value of the region boundary’s grayscale discontinuity characteristics, takes the grayscale value with the least number of discontinuity areas in the grayscale histogram as a segmentation threshold adapted to the characteristics of the sea fog image to segment bright areas such as the sky, and then uses grayscale gradients to identify grayscale differences in different bright areas, accurately distinguishing boundaries between sky and non-sky areas. By comparing the area parameters, non-sky blocks are filled; this adaptively eliminates interference from other bright non-sky areas and accurately locks the sky area. Furthermore, this study proposes an enhanced dark channel prior approach that optimizes transmittance locally within sky areas and globally across the image. This is achieved using a transmittance optimization algorithm combined with guided filtering technology. The atmospheric light estimation is refined through iterative adjustments, ensuring consistency in brightness between the dehazed and original images. The image reconstruction employs calculated atmospheric light and transmittance values through an atmospheric scattering model. Finally, the use of gamma-correction technology ensures that images more accurately replicate natural colors and brightness levels. Experimental outcomes demonstrate substantial improvements in the contrast, color saturation, and visual clarity of marine fog images. Additionally, a set of foggy marine image data sets is developed for monitoring purposes. Compared with traditional dark channel prior dehazing techniques, this new approach significantly improves fog removal. This advancement enhances the clarity of images obtained from maritime equipment and effectively mitigates the risk of maritime transportation accidents.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778781","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 Atlantic pearl oyster, Pinctada radiata (Leach, 1814), is an Indo-Pacific bivalve of the subtidal zone that has colonized habitats all over the Mediterranean. There is a lack of detailed information on the reproductive activity of P. radiata in Hellenic waters, especially following the recent amendment of national legislation aiming to regulate the fishery and prevent illegal fishing and trafficking as a substitute for indigenous oysters. A total of 703 individuals were collected by scuba diving from the southwest part of Evia Island. Gonad microscopic examination indicated that gametogenesis occurs from February to September, with a recovery stage in early autumn. Synchronicity occurs for both sexes, with temperature being the main controlling factor. The annual recruitment pattern indicated two prominent peaks of similar magnitude. Analysis of covariance indicated a significant temperature effect on gonad index above 22 degrees. Onset of sexual maturity (L50) was estimated at 47.2 mm in shell height and 27.09 gr in total weight for the entire population. The sex ratio was in favor of females at 1:1.70, with 7% and 19% of the individuals assessed macroscopically and microscopically identified as hermaphrodites, respectively. Results offer valuable information for the management and conservation of pearl oyster populations.
{"title":"Reproductive Biology of Pearl Oyster (Pinctada radiata, Leach 1814) Based on Microscopic and Macroscopic Assessment of Both Sexes in the Eastern Mediterranean (South Evia Island)","authors":"Dimitris Pafras, Chrysoula Apostologamvrou, Athina Balatsou, Alexandros Theocharis, Alexios Lolas, Marianthi Hatziioannou, Dimitris Vafidis, Dimitris Klaoudatos","doi":"10.3390/jmse12081259","DOIUrl":"https://doi.org/10.3390/jmse12081259","url":null,"abstract":"The Atlantic pearl oyster, Pinctada radiata (Leach, 1814), is an Indo-Pacific bivalve of the subtidal zone that has colonized habitats all over the Mediterranean. There is a lack of detailed information on the reproductive activity of P. radiata in Hellenic waters, especially following the recent amendment of national legislation aiming to regulate the fishery and prevent illegal fishing and trafficking as a substitute for indigenous oysters. A total of 703 individuals were collected by scuba diving from the southwest part of Evia Island. Gonad microscopic examination indicated that gametogenesis occurs from February to September, with a recovery stage in early autumn. Synchronicity occurs for both sexes, with temperature being the main controlling factor. The annual recruitment pattern indicated two prominent peaks of similar magnitude. Analysis of covariance indicated a significant temperature effect on gonad index above 22 degrees. Onset of sexual maturity (L50) was estimated at 47.2 mm in shell height and 27.09 gr in total weight for the entire population. The sex ratio was in favor of females at 1:1.70, with 7% and 19% of the individuals assessed macroscopically and microscopically identified as hermaphrodites, respectively. Results offer valuable information for the management and conservation of pearl oyster populations.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778858","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}
In October 2021, the editorial office invited Prof [...]
2021 年 10 月，编辑部邀请[......］
{"title":"Advances in Marine Engineering: Geological Environment and Hazards II","authors":"Xingsen Guo, Xiaolei Liu, Thorsten Stoesser","doi":"10.3390/jmse12081253","DOIUrl":"https://doi.org/10.3390/jmse12081253","url":null,"abstract":"In October 2021, the editorial office invited Prof [...]","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778778","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}
Han Zheng, Haonan Chen, Anqi Du, Meijiao Yang, Zhigang Jin, Ye Chen
With the wide application of Underwater Wireless Sensor Networks (UWSNs) in various fields, more and more attention has been paid to deploying and adjusting network nodes. A UWSN is composed of nodes with limited mobility. Drift movement leads to the network structure’s destruction, communication performance decline, and node life-shortening. Therefore, a Node Adjustment Scheme based on Motion Prediction (NAS-MP) is proposed, which integrates the layered model of the ocean current’s uneven depth, the layered ocean current prediction model based on convolutional neural network (CNN)–transformer, the node trajectory prediction model, and the periodic depth adjustment model based on the Seagull Optimization Algorithm (SOA), to improve the network coverage and connectivity. Firstly, the error threshold of the current velocity and direction in the layer was introduced to divide the depth levels, and the regional current data model was constructed according to the measured data. Secondly, the CNN–transformer hybrid network was used to predict stratified ocean currents. Then, the prediction data of layered ocean currents was applied to the nodes’ drift model, and the nodes’ motion trajectory prediction was obtained. Finally, based on the trajectory prediction of nodes, the SOA obtained the optimal depth of nodes to optimize the coverage and connectivity of the UWSN. Experimental simulation results show that the performance of the proposed scheme is superior.
{"title":"Node Adjustment Scheme of Underwater Wireless Sensor Networks Based on Motion Prediction Model","authors":"Han Zheng, Haonan Chen, Anqi Du, Meijiao Yang, Zhigang Jin, Ye Chen","doi":"10.3390/jmse12081256","DOIUrl":"https://doi.org/10.3390/jmse12081256","url":null,"abstract":"With the wide application of Underwater Wireless Sensor Networks (UWSNs) in various fields, more and more attention has been paid to deploying and adjusting network nodes. A UWSN is composed of nodes with limited mobility. Drift movement leads to the network structure’s destruction, communication performance decline, and node life-shortening. Therefore, a Node Adjustment Scheme based on Motion Prediction (NAS-MP) is proposed, which integrates the layered model of the ocean current’s uneven depth, the layered ocean current prediction model based on convolutional neural network (CNN)–transformer, the node trajectory prediction model, and the periodic depth adjustment model based on the Seagull Optimization Algorithm (SOA), to improve the network coverage and connectivity. Firstly, the error threshold of the current velocity and direction in the layer was introduced to divide the depth levels, and the regional current data model was constructed according to the measured data. Secondly, the CNN–transformer hybrid network was used to predict stratified ocean currents. Then, the prediction data of layered ocean currents was applied to the nodes’ drift model, and the nodes’ motion trajectory prediction was obtained. Finally, based on the trajectory prediction of nodes, the SOA obtained the optimal depth of nodes to optimize the coverage and connectivity of the UWSN. Experimental simulation results show that the performance of the proposed scheme is superior.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778860","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}
Misun Yun, Jae-Joong Kang, Yubeen Jeong, Young-Heon Jo, Jun Sun, Sang-Heon Lee
Solar radiation, particularly ultraviolet radiation (UVR, 280–400 nm), is known to play a significant role in driving primary production in marine ecosystems. However, our understanding of the specific effects of UVR on the primary production of natural phytoplankton communities is still limited. We utilized the 13C stable isotope to quantify primary production and conducted experiments using different types of incubation bottles (polycarbonate and quartz bottles) to compare the primary production in the absence and presence of UVR. Although we observed a weak inhibitory effect at the surface of the water column, UVR exposure resulted in an approximately 1.5-fold increase in primary production over the euphotic zone. The enhanced primary production during the study period can be attributed to the combined effect of low UVB (280–320 nm) dose and abundant nutrient conditions. Notably, our size-fractionated measurements revealed that UVR exposure led to a two-fold increase in primary production in large cells (>2 μm) compared to the exposure of solely photosynthetically active radiation (PAR). In contrast, there was no significant difference in the primary production of small cells (<2 μm) between the absence and presence of UVR. These findings highlight the advantages of large cells when exposed to UVR, emphasizing the importance of phytoplankton cell size in determining their response to UVR. However, it is important to note that the effects of UVR on phytoplankton are influenced by various environmental factors, which interact with solar radiation, shaping the dynamics of phytoplankton responses to UVR.
{"title":"Experimental Assessment of Ultraviolet Radiation Impact on the Primary Production of Phytoplankton in the East/Japan Sea","authors":"Misun Yun, Jae-Joong Kang, Yubeen Jeong, Young-Heon Jo, Jun Sun, Sang-Heon Lee","doi":"10.3390/jmse12081258","DOIUrl":"https://doi.org/10.3390/jmse12081258","url":null,"abstract":"Solar radiation, particularly ultraviolet radiation (UVR, 280–400 nm), is known to play a significant role in driving primary production in marine ecosystems. However, our understanding of the specific effects of UVR on the primary production of natural phytoplankton communities is still limited. We utilized the 13C stable isotope to quantify primary production and conducted experiments using different types of incubation bottles (polycarbonate and quartz bottles) to compare the primary production in the absence and presence of UVR. Although we observed a weak inhibitory effect at the surface of the water column, UVR exposure resulted in an approximately 1.5-fold increase in primary production over the euphotic zone. The enhanced primary production during the study period can be attributed to the combined effect of low UVB (280–320 nm) dose and abundant nutrient conditions. Notably, our size-fractionated measurements revealed that UVR exposure led to a two-fold increase in primary production in large cells (>2 μm) compared to the exposure of solely photosynthetically active radiation (PAR). In contrast, there was no significant difference in the primary production of small cells (<2 μm) between the absence and presence of UVR. These findings highlight the advantages of large cells when exposed to UVR, emphasizing the importance of phytoplankton cell size in determining their response to UVR. However, it is important to note that the effects of UVR on phytoplankton are influenced by various environmental factors, which interact with solar radiation, shaping the dynamics of phytoplankton responses to UVR.","PeriodicalId":16168,"journal":{"name":"Journal of Marine Science and Engineering","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778859","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：