Pub Date : 2025-08-01Epub Date: 2023-12-23DOI: 10.1016/j.joes.2023.12.004
Yongjin Guo , Chao Gao , Yang Jin , Yintao Li , Jianyao Wang , Qing Li , Hongdong Wang
The operating conditions of marine machinery are demanding, and their operational state significantly affects the safety of marine structures. Detecting faults is crucial for machinery health management and necessitates a highly precise diagnostic method. In this paper, we propose a fault diagnosis framework that employs transfer learning and dynamics simulation. A denoising convolutional autoencoder is used to reduce noise when monitoring vibration data in marine environments. To address the challenge of limited sample sizes in marine machinery fault data, a multibody dynamics simulation model is developed to acquire data under fault conditions. The fault features are extracted using a convolutional neural network model. Parameter transfer is applied to enhance the accuracy of fault diagnosis. The effectiveness and applicability of the framework are demonstrated through a case study of a bearing fault dataset.
{"title":"A transfer learning-based method for marine machinery diagnosis with small samples in noisy environments","authors":"Yongjin Guo , Chao Gao , Yang Jin , Yintao Li , Jianyao Wang , Qing Li , Hongdong Wang","doi":"10.1016/j.joes.2023.12.004","DOIUrl":"10.1016/j.joes.2023.12.004","url":null,"abstract":"<div><div>The operating conditions of marine machinery are demanding, and their operational state significantly affects the safety of marine structures. Detecting faults is crucial for machinery health management and necessitates a highly precise diagnostic method. In this paper, we propose a fault diagnosis framework that employs transfer learning and dynamics simulation. A denoising convolutional autoencoder is used to reduce noise when monitoring vibration data in marine environments. To address the challenge of limited sample sizes in marine machinery fault data, a multibody dynamics simulation model is developed to acquire data under fault conditions. The fault features are extracted using a convolutional neural network model. Parameter transfer is applied to enhance the accuracy of fault diagnosis. The effectiveness and applicability of the framework are demonstrated through a case study of a bearing fault dataset.</div></div>","PeriodicalId":48514,"journal":{"name":"Journal of Ocean Engineering and Science","volume":"10 4","pages":"Pages 593-601"},"PeriodicalIF":13.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139190660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Normally, small unmanned vessels used to clean floating litter on water adopt a paddle wheel as a propulsor to satisfy its shallow-draft requirements; however, this type of propulsor has bulky structures and inefficient propulsion. In this study, a novel tandem paddles propulsor (TPP) was developed, and its propulsion performance was analyzed and compared with that of a paddle wheel propulsor (PWP). Using the RNG k-ε turbulence model and sliding grid technique, the hydrodynamic performance of the PWP was simulated in computational fluid dynamics (CFD) software to verify the reliability of the numerical method. Subsequently, the propulsion performances of the two types of propulsors were simulated with different immersion depths and advanced coefficients, and the differences in their mechanical characteristics and flow field evolution were discussed and compared. The results indicate that the proposed TPP generates 2.75 times more thrust and 1.99 times greater efficiency than the PWP, exhibiting superior propulsion capability in shallow-draft vessels.
{"title":"Numerical and experimental studies on propulsion performance of a novel tandem paddles propulsor","authors":"Longqing Xin, Peng Liu, Huajun Li, Siqi Wang, Yuhua Lyu, Yaqian Li, Guodong Feng","doi":"10.1016/j.joes.2024.08.001","DOIUrl":"10.1016/j.joes.2024.08.001","url":null,"abstract":"<div><div>Normally, small unmanned vessels used to clean floating litter on water adopt a paddle wheel as a propulsor to satisfy its shallow-draft requirements; however, this type of propulsor has bulky structures and inefficient propulsion. In this study, a novel tandem paddles propulsor (TPP) was developed, and its propulsion performance was analyzed and compared with that of a paddle wheel propulsor (PWP). Using the RNG <em>k-ε</em> turbulence model and sliding grid technique, the hydrodynamic performance of the PWP was simulated in computational fluid dynamics (CFD) software to verify the reliability of the numerical method. Subsequently, the propulsion performances of the two types of propulsors were simulated with different immersion depths and advanced coefficients, and the differences in their mechanical characteristics and flow field evolution were discussed and compared. The results indicate that the proposed TPP generates 2.75 times more thrust and 1.99 times greater efficiency than the PWP, exhibiting superior propulsion capability in shallow-draft vessels.</div></div>","PeriodicalId":48514,"journal":{"name":"Journal of Ocean Engineering and Science","volume":"10 4","pages":"Pages 475-491"},"PeriodicalIF":13.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-01Epub Date: 2024-03-19DOI: 10.1016/j.joes.2024.03.001
Marianela Machuca Macias , Rafael Castilho Faria Mendes , José Hermenegildo Garcia-Ortiz , Taygoara Felamingo Oliveira , Antonio C.P. Brasil Junior
The environmental effects of hydrokinetic turbines are still under investigation, reflecting the emerging status of this technology. This study investigates the interaction between hydrokinetic rotor wakes and fish swimming, revealing insights into fish biomechanics in complex flows and assessing the environmental implications of marine energy solutions. We conducted numerical simulations with the URANS approach and turbulence closure model to predict three-dimensional turbulent flow in the OpenFOAM software. The hydrokinetic rotor wake was simulated employing the actuator line method, providing a computationally efficient alternative to full geometry simulations. For accurate replication of the motion of a fish-like tuna (Thunnus atlanticus), dynamic adaptive mesh discretization was employed. The results offer a comparative analysis of fish swimming performance within the wake rotor, particularly when immersed in the tip blade vortex, contrasted with scenarios where fish swim in undisturbed flow conditions. The analysis encompasses three-dimensional wake structures, force generation, efficiency, and equilibrium states (balancing drag and thrust) across varying Swimming numbers (). Key findings include the enhanced attachment of the leading-edge vortex due to the caudal fin’s interaction with the tip blade vortex, resulting in improved auto-propulsive force production; a reduced tail stride frequency observed in fish swimming downstream of the rotor to achieve longitudinal force balance compared to unperturbed flow; and transverse hydrodynamic forces pushing fish radially away from the wake’s influence zone, potentially mitigating the risk of collision with turbine blades.
{"title":"Numerical study of a fish swimming in hydrokinetic turbine wake","authors":"Marianela Machuca Macias , Rafael Castilho Faria Mendes , José Hermenegildo Garcia-Ortiz , Taygoara Felamingo Oliveira , Antonio C.P. Brasil Junior","doi":"10.1016/j.joes.2024.03.001","DOIUrl":"10.1016/j.joes.2024.03.001","url":null,"abstract":"<div><div>The environmental effects of hydrokinetic turbines are still under investigation, reflecting the emerging status of this technology. This study investigates the interaction between hydrokinetic rotor wakes and fish swimming, revealing insights into fish biomechanics in complex flows and assessing the environmental implications of marine energy solutions. We conducted numerical simulations with the URANS approach and <span><math><mrow><mi>k</mi><mspace></mspace><mo>−</mo><mspace></mspace><mi>ω</mi><mspace></mspace><mo>−</mo><mspace></mspace><mi>S</mi><mi>S</mi><mi>T</mi></mrow></math></span> turbulence closure model to predict three-dimensional turbulent flow in the OpenFOAM software. The hydrokinetic rotor wake was simulated employing the actuator line method, providing a computationally efficient alternative to full geometry simulations. For accurate replication of the motion of a fish-like tuna (<em>Thunnus atlanticus</em>), dynamic adaptive mesh discretization was employed. The results offer a comparative analysis of fish swimming performance within the wake rotor, particularly when immersed in the tip blade vortex, contrasted with scenarios where fish swim in undisturbed flow conditions. The analysis encompasses three-dimensional wake structures, force generation, efficiency, and equilibrium states (balancing drag and thrust) across varying Swimming numbers (<span><math><mrow><mi>S</mi><mi>w</mi></mrow></math></span>). Key findings include the enhanced attachment of the leading-edge vortex due to the caudal fin’s interaction with the tip blade vortex, resulting in improved auto-propulsive force production; a reduced tail stride frequency observed in fish swimming downstream of the rotor to achieve longitudinal force balance compared to unperturbed flow; and transverse hydrodynamic forces pushing fish radially away from the wake’s influence zone, potentially mitigating the risk of collision with turbine blades.</div></div>","PeriodicalId":48514,"journal":{"name":"Journal of Ocean Engineering and Science","volume":"10 4","pages":"Pages 602-620"},"PeriodicalIF":13.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140269457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-01Epub Date: 2022-06-17DOI: 10.1016/j.joes.2022.06.030
Susmita Saha , Satyasaran Changdar , Soumen De
An important issue in designing the structures of rubble-mound breakwaters, is to estimate the stability number of its armor block. Most of the traditional stability analysis methods are not compatible enough to handle the obscurities, indistintness and uncertainties of this field. The relations between stability number, damage level and other stability variables can better be modeled using the advanced techniques of machine learning (ML) algorithms. In this prospect, three new ML models consisting of two ensemble learning models; Random Forest, Gradient Boosting and one fully connected deep artificial neural network based prediction model have been presented in this study. Using the ensemble learning models a detailed feature analysis has been introduced here, to understand the feature importances of stability variables on the stability number. To the best of the author’s knowledge, these have never been used in this field of stability analysis of rubble-mound breakwaters. Outperforming all of the conventional methods, the proposed study has delivered the highest level of accuracy as 99%, in the prediction of the stability number. Also, the proposed ML models are found to perform better, in dealing with the complex non-linearities related to this field. The feature analysis gives a meaningful insight into the dataset. Therefore, this study can be a useful alternative approach for the designers of the rubble-mound breakwaters.
{"title":"Prediction of the stability number of conventional rubble-mound breakwaters using machine learning algorithms","authors":"Susmita Saha , Satyasaran Changdar , Soumen De","doi":"10.1016/j.joes.2022.06.030","DOIUrl":"10.1016/j.joes.2022.06.030","url":null,"abstract":"<div><div>An important issue in designing the structures of rubble-mound breakwaters, is to estimate the stability number of its armor block. Most of the traditional stability analysis methods are not compatible enough to handle the obscurities, indistintness and uncertainties of this field. The relations between stability number, damage level and other stability variables can better be modeled using the advanced techniques of machine learning (ML) algorithms. In this prospect, three new ML models consisting of two ensemble learning models; Random Forest, Gradient Boosting and one fully connected deep artificial neural network based prediction model have been presented in this study. Using the ensemble learning models a detailed feature analysis has been introduced here, to understand the feature importances of stability variables on the stability number. To the best of the author’s knowledge, these have never been used in this field of stability analysis of rubble-mound breakwaters. Outperforming all of the conventional methods, the proposed study has delivered the highest level of accuracy as 99%, in the prediction of the stability number. Also, the proposed ML models are found to perform better, in dealing with the complex non-linearities related to this field. The feature analysis gives a meaningful insight into the dataset. Therefore, this study can be a useful alternative approach for the designers of the rubble-mound breakwaters.</div></div>","PeriodicalId":48514,"journal":{"name":"Journal of Ocean Engineering and Science","volume":"10 4","pages":"Pages 438-448"},"PeriodicalIF":13.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41425914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ballast water is essential for cargo ships since it stabilizes vessels at sea. Most ships are equipped with a ballast water system (BWS) to maintain safe operating conditions. This paper attempts to perform a risk assessment for the BWS on-board tanker ship as it poses a major threat to the operational safety of the ship, marine environment, and cargo. To achieve this purpose, the paper utilizes a robust methodology integrating D-S evidence (Dempster-Shafer) theory and FMECA (Failure mode effects and criticality analysis). In the methodology, while the D-S evidence theory introduces a proper mathematical framework to handle epistemic uncertainty in the assessment of risk parameters and to prioritize failure modes as intended, the FMECA is capable of evaluating system potential failures and their causes. Hence, the risk priority number (RPN) can be calculated to assess potential hazards and their consequences in BWS on-board ships. Besides its theoretical insight, the paper contributes to marine safety inspectors, safety researchers, and HSEQ (Health, Safety, Environment, and Quality) managers to identify potential hazards, effects, and consequences in case of BWS failures on-board tanker ships.
{"title":"D-S evidence based FMECA approach to assess potential risks in ballast water system (BWS) on-board tanker ship","authors":"Sukru Ilke Sezer , Bulut Ozan Ceylan , Emre Akyuz , Ozcan Arslan","doi":"10.1016/j.joes.2022.06.040","DOIUrl":"10.1016/j.joes.2022.06.040","url":null,"abstract":"<div><div>Ballast water is essential for cargo ships since it stabilizes vessels at sea. Most ships are equipped with a ballast water system (BWS) to maintain safe operating conditions. This paper attempts to perform a risk assessment for the BWS on-board tanker ship as it poses a major threat to the operational safety of the ship, marine environment, and cargo. To achieve this purpose, the paper utilizes a robust methodology integrating D-S evidence (Dempster-Shafer) theory and FMECA (Failure mode effects and criticality analysis). In the methodology, while the D-S evidence theory introduces a proper mathematical framework to handle epistemic uncertainty in the assessment of risk parameters and to prioritize failure modes as intended, the FMECA is capable of evaluating system potential failures and their causes. Hence, the risk priority number (RPN) can be calculated to assess potential hazards and their consequences in BWS on-board ships. Besides its theoretical insight, the paper contributes to marine safety inspectors, safety researchers, and HSEQ (Health, Safety, Environment, and Quality) managers to identify potential hazards, effects, and consequences in case of BWS failures on-board tanker ships.</div></div>","PeriodicalId":48514,"journal":{"name":"Journal of Ocean Engineering and Science","volume":"10 4","pages":"Pages 509-520"},"PeriodicalIF":13.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41270476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-01Epub Date: 2023-09-09DOI: 10.1016/j.joes.2023.09.001
Shunzhao Cheng, Jun Wang, Jian Wang, Xiaofeng Liang, Hong Yi
The key to achieving the optimal design of towed cables, maintaining numerical simulation accuracy, and achieving precise control of the towed body lies in sensitivity analysis. However, the traditional global sensitivity analysis method presents challenges such as high calculation costs and low accuracy. To address these issues, this paper introduces polynomial chaos expansion (PCE) to quantitatively analyze the impact of uncertainties in physical and environmental parameters on the position and attitude of the towed cable. Latin hypercube sampling is employed to obtain sample sets of input parameters, and these samples are applied to the lumped mass method to calculate the end position coordinates of the towed cable, which serves as the output response. PCE is utilized to quantitatively compute the Sobol global sensitivity index of the towed cable parameters. The accuracy of the PCE model is verified, and the optimal degree of basis functions is selected using the bias-variance trade-off. The advantages of PCE are demonstrated by comparing it with the Monte Carlo and Morris methods. The results indicate that PCE accurately calculates the global sensitivity index of towed cable parameters even with a limited sample size. Under the condition of a fixed cable length, the position and attitude of the towed cable are sensitive to the current rate, liquid density, cable diameter, normal drag coefficient, and specific gravity. The feasibility and efficiency of PCE applied to the sensitivity analysis of towed cable parameters is verified, and recommendations for the engineering application of towed cables are summarized.
{"title":"Application of polynomial chaos expansion in sensitivity analysis of towed cable parameters of the underwater towing system","authors":"Shunzhao Cheng, Jun Wang, Jian Wang, Xiaofeng Liang, Hong Yi","doi":"10.1016/j.joes.2023.09.001","DOIUrl":"10.1016/j.joes.2023.09.001","url":null,"abstract":"<div><div>The key to achieving the optimal design of towed cables, maintaining numerical simulation accuracy, and achieving precise control of the towed body lies in sensitivity analysis. However, the traditional global sensitivity analysis method presents challenges such as high calculation costs and low accuracy. To address these issues, this paper introduces polynomial chaos expansion (PCE) to quantitatively analyze the impact of uncertainties in physical and environmental parameters on the position and attitude of the towed cable. Latin hypercube sampling is employed to obtain sample sets of input parameters, and these samples are applied to the lumped mass method to calculate the end position coordinates of the towed cable, which serves as the output response. PCE is utilized to quantitatively compute the Sobol global sensitivity index of the towed cable parameters. The accuracy of the PCE model is verified, and the optimal degree of basis functions is selected using the bias-variance trade-off. The advantages of PCE are demonstrated by comparing it with the Monte Carlo and Morris methods. The results indicate that PCE accurately calculates the global sensitivity index of towed cable parameters even with a limited sample size. Under the condition of a fixed cable length, the position and attitude of the towed cable are sensitive to the current rate, liquid density, cable diameter, normal drag coefficient, and specific gravity. The feasibility and efficiency of PCE applied to the sensitivity analysis of towed cable parameters is verified, and recommendations for the engineering application of towed cables are summarized.</div></div>","PeriodicalId":48514,"journal":{"name":"Journal of Ocean Engineering and Science","volume":"10 4","pages":"Pages 367-385"},"PeriodicalIF":13.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135200205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-01Epub Date: 2023-09-04DOI: 10.1016/j.joes.2023.08.006
Xuepeng Fu , Shixiao Fu , Zhaolong Han , Zhibo Niu , Mengmeng Zhang , Bing Zhao
Finding a reliable and efficient numerical method is of great importance for the safety design of a offshore riser whose model can be simplified as vortex-induced vibration (VIV) of an elastically-mounted circular cylinder. In the current study, two-degree-of-freedom (2-DOF) VIV responses of a circular cylinder with a small mass ratio and small mass damping parameter is numerically investigated by two- and three-dimensional method. The simulations by using the URANS (Unsteady Reynolds Averaged Navier-Stokes) in combination with the SST (Shear Stress Transport) turbulence model are performed at subcritical Reynolds numbers ( ranges from to ). From the overall results, both the 2D and 3D simulations can obtain relatively accurate statistical results including VIV response amplitudes and frequency values. The main differences between the 2D and 3D simulations lie on the three-dimensional effects that exist in the supper upper branch and the flow transition condition. However, the 2D numerical simulations can save hundreds of times of the computational resources compared with a 3D simulation, hence is more suitable for engineering VIV prediction under such conditions. The comparison of simulation and experimental results in this study provides research support for the selection of appropriate simulation methods (2D or 3D) for 2-DOF VIV of an offshore riser in research and engineering.
{"title":"Numerical simulations of 2-DOF vortex-induced vibration of a circular cylinder in two and three dimensions: A comparison study","authors":"Xuepeng Fu , Shixiao Fu , Zhaolong Han , Zhibo Niu , Mengmeng Zhang , Bing Zhao","doi":"10.1016/j.joes.2023.08.006","DOIUrl":"10.1016/j.joes.2023.08.006","url":null,"abstract":"<div><div>Finding a reliable and efficient numerical method is of great importance for the safety design of a offshore riser whose model can be simplified as vortex-induced vibration (VIV) of an elastically-mounted circular cylinder. In the current study, two-degree-of-freedom (2-DOF) VIV responses of a circular cylinder with a small mass ratio <span><math><mrow><msup><mi>m</mi><mo>*</mo></msup><mo>=</mo><mn>2.6</mn></mrow></math></span> and small mass damping parameter <span><math><mrow><mo>(</mo><msup><mi>m</mi><mo>*</mo></msup><mo>+</mo><mn>1</mn><mo>)</mo><mi>ζ</mi><mo>=</mo><mn>0.013</mn></mrow></math></span> is numerically investigated by two- and three-dimensional method. The simulations by using the URANS (Unsteady Reynolds Averaged Navier-Stokes) in combination with the SST (Shear Stress Transport) <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> turbulence model are performed at subcritical Reynolds numbers (<span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span> ranges from <span><math><mrow><mn>1</mn><mo>×</mo><msup><mn>10</mn><mn>3</mn></msup></mrow></math></span> to <span><math><mrow><mn>1.5</mn><mo>×</mo><msup><mn>10</mn><mn>4</mn></msup></mrow></math></span>). From the overall results, both the 2D and 3D simulations can obtain relatively accurate statistical results including VIV response amplitudes and frequency values. The main differences between the 2D and 3D simulations lie on the three-dimensional effects that exist in the supper upper branch and the flow transition condition. However, the 2D numerical simulations can save hundreds of times of the computational resources compared with a 3D simulation, hence is more suitable for engineering VIV prediction under such conditions. The comparison of simulation and experimental results in this study provides research support for the selection of appropriate simulation methods (2D or 3D) for 2-DOF VIV of an offshore riser in research and engineering.</div></div>","PeriodicalId":48514,"journal":{"name":"Journal of Ocean Engineering and Science","volume":"10 4","pages":"Pages 395-410"},"PeriodicalIF":13.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45640874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-01Epub Date: 2024-06-03DOI: 10.1016/j.joes.2024.05.003
Li Sun , Deyu Wang , Guijie Shi
Identification of impact loads plays important role in marine structures health monitoring but is difficult to be measured directly most time. This study investigates a two-stage framework for impact load localization and reconstruction, consisting of load region identification and local refined nodal search. For the region identification, a novel frequency response feature preprocessing method based on FFT is proposed and incorporated into a multi-layer perceptron (MLP) neural network as the embedding function of the Matching Network (MN), the core model adopted for pattern recognition. Based on the region probabilities predicted by MN, a local refined nodal search strategy is provided, which is initialized by a region correction method for amending the possible region misclassification and further guided by error metrics with iteration search strategy. Moreover, the inverse problem in this study is formulated in the discretized state space expression with the reduced modal coordinates. For improving the load inverse accuracy affected by Zero Order Hold (ZOH) simplification in this formulation, a dynamic sensor filter strategy is provided. Eventually, a numerical experiment of impact load identification on a steel plate is performed and discussed, whose results indicate the validity and robustness of the proposed method.
{"title":"Impact load identification method based on frequency response pattern recognition and dynamic sensor filter strategy","authors":"Li Sun , Deyu Wang , Guijie Shi","doi":"10.1016/j.joes.2024.05.003","DOIUrl":"10.1016/j.joes.2024.05.003","url":null,"abstract":"<div><div>Identification of impact loads plays important role in marine structures health monitoring but is difficult to be measured directly most time. This study investigates a two-stage framework for impact load localization and reconstruction, consisting of load region identification and local refined nodal search. For the region identification, a novel frequency response feature preprocessing method based on FFT is proposed and incorporated into a multi-layer perceptron (MLP) neural network as the embedding function of the Matching Network (MN), the core model adopted for pattern recognition. Based on the region probabilities predicted by MN, a local refined nodal search strategy is provided, which is initialized by a region correction method for amending the possible region misclassification and further guided by error metrics with iteration search strategy. Moreover, the inverse problem in this study is formulated in the discretized state space expression with the reduced modal coordinates. For improving the load inverse accuracy affected by Zero Order Hold (ZOH) simplification in this formulation, a dynamic sensor filter strategy is provided. Eventually, a numerical experiment of impact load identification on a steel plate is performed and discussed, whose results indicate the validity and robustness of the proposed method.</div></div>","PeriodicalId":48514,"journal":{"name":"Journal of Ocean Engineering and Science","volume":"10 4","pages":"Pages 411-425"},"PeriodicalIF":13.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141275401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-01Epub Date: 2025-01-11DOI: 10.1016/j.joes.2024.11.002
Chern Fong Lee, Sindre Fjermedal, Muk Chen Ong
For intermediate water depths (typically ranging from 50 m to 80 m), designing steel catenary mooring systems for floating marine renewable energy (FMRE) platforms can be challenging due to the limited weight of suspended mooring lines. This can substantially increase mooring line tensions following large platform offsets. In contrast, mooring systems using synthetic fibre ropes offer the potential to prevent large platform offsets while reducing peak mooring line tensions. In this study, novel semi-taut mooring systems incorporating polyester ropes and steel chains are proposed for a combined wind and wave energy system – the semi-submersible flap torus combination (STFC) concept, deployed at a 50 m water depth. The STFC integrates a semi-submersible floating offshore wind turbine (FOWT), a torus wave energy converter (WEC) and three flap-type WECs. The dynamic responses of the STFC with different semi-taut mooring configurations under operational and survival environmental conditions are assessed in terms of key performance parameters such as the platform's motion responses and mooring line tensions. These performance parameters are compared against those of a chain-catenary mooring system. With the use of semi-taut mooring systems, significantly smaller mooring footprints as compared to the chain-catenary mooring systems can be achieved. Moreover, it is demonstrated that the semi-taut mooring systems are effective in reducing the maximum tension of the mooring lines. A basic cost analysis further indicates that semi-taut mooring systems offer substantial cost advantages over chain-catenary moorings in intermediate water depths.
{"title":"Design and comparative analysis of mooring systems for a combined wind and wave energy system at intermediate water depth","authors":"Chern Fong Lee, Sindre Fjermedal, Muk Chen Ong","doi":"10.1016/j.joes.2024.11.002","DOIUrl":"10.1016/j.joes.2024.11.002","url":null,"abstract":"<div><div>For intermediate water depths (typically ranging from 50 m to 80 m), designing steel catenary mooring systems for floating marine renewable energy (FMRE) platforms can be challenging due to the limited weight of suspended mooring lines. This can substantially increase mooring line tensions following large platform offsets. In contrast, mooring systems using synthetic fibre ropes offer the potential to prevent large platform offsets while reducing peak mooring line tensions. In this study, novel semi-taut mooring systems incorporating polyester ropes and steel chains are proposed for a combined wind and wave energy system – the semi-submersible flap torus combination (STFC) concept, deployed at a 50 m water depth. The STFC integrates a semi-submersible floating offshore wind turbine (FOWT), a torus wave energy converter (WEC) and three flap-type WECs. The dynamic responses of the STFC with different semi-taut mooring configurations under operational and survival environmental conditions are assessed in terms of key performance parameters such as the platform's motion responses and mooring line tensions. These performance parameters are compared against those of a chain-catenary mooring system. With the use of semi-taut mooring systems, significantly smaller mooring footprints as compared to the chain-catenary mooring systems can be achieved. Moreover, it is demonstrated that the semi-taut mooring systems are effective in reducing the maximum tension of the mooring lines. A basic cost analysis further indicates that semi-taut mooring systems offer substantial cost advantages over chain-catenary moorings in intermediate water depths.</div></div>","PeriodicalId":48514,"journal":{"name":"Journal of Ocean Engineering and Science","volume":"10 4","pages":"Pages 492-508"},"PeriodicalIF":13.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-01Epub Date: 2023-10-30DOI: 10.1016/j.joes.2023.10.005
Shoaib Ahmed , Tie Li , Shi Yan Li , Run Chen
Offshore Anchor handling tug supply (AHTS) vessels, a type of offshore support vessel, are critical for the operations related to handling anchors of offshore structures, oil rigs, and wind turbines, towing them to remote deep-sea locations, and securing them in place. Amidst growing concerns regarding the environmental footprints of carbon-based fuels and impending carbon taxation, the International Maritime Organization, policymakers, classification societies, shipping firms, and stakeholders are seeking cleaner alternatives. LNG (Liquefied natural gas) and Green ammonia as energy vectors are considered among the top contenders for future clean alternatives for offshore vessels. This study evaluated the environmental performance of newly built AHTS vessels powered by LNG and Green ammonia as marine fuels designed for offshore operations. This environmental impact assessment study uses IPCC and Environmental footprint methodologies. Considered broad impact groups: Global warming, human toxicity, eutrophication, ecotoxicity, and atmosphere-related impacts, and analyzed the process impacts. This study uses Supervised machine learning algorithms such as the Random forest, Decision tree, and XGBOOST models for environmental performance evaluation and prediction. The study reveals that the recently manufactured AHTS vessel, utilizing conventional fuels like Heavy fuel oil, Marine diesel oil, and LNG, exhibits significantly increased GTP 100 and GWP 100 emission levels per tonne-kilometer when compared to green ammonia, with a 44 % and 10.6 % rise compared to Heavy fuel oil, respectively. Furthermore, the XGBOOST regression model outperformed the Random forest and Decision tree models in predictive accuracy for GWP 100. It is analyzed and proposed that effectively managing unsustainable processes would minimize environmental footprints and reduce carbon, nitrogen oxide, LNG, and ammonia-based emissions.
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