Pub Date : 2025-01-01DOI: 10.1016/j.ijnaoe.2025.100706
Yulong Tuo , Lebin Kong , Shaolong Geng , Zhouhua Peng , Shasha Wang
This paper proposes a fixed-time event-triggered anti-windup collaborative controller for a towing system consisting of an unactuated offshore platform and multiple tugs. Firstly, a fixed-time virtual controller is proposed to acquire required towing force for the platform to track expected trajectory. Subsequently, the required towing force is allocated as desired towline tensions by quadratic programming algorithm, and corresponding desired length of each towline is calculated through towline catenary model. Based on desired towline tensions and lengths, a fixed-time collaborative controller is constructed for tugs with following key components: the input saturation of tugs is approximated by a Gaussian error function; a fixed-time extended state observer is employed to rapidly estimate compound disturbances including saturation approximation errors; a novel dynamic threshold event-triggered mechanism is designed to decrease the control input update frequency while maintaining the convergence performance of entire control system. Finally, simulation results demonstrate the effectiveness of proposed control method.
{"title":"Fixed-time dynamic threshold event-triggered anti-windup collaborative control for multi-tug towing of unactuated offshore floating platform","authors":"Yulong Tuo , Lebin Kong , Shaolong Geng , Zhouhua Peng , Shasha Wang","doi":"10.1016/j.ijnaoe.2025.100706","DOIUrl":"10.1016/j.ijnaoe.2025.100706","url":null,"abstract":"<div><div>This paper proposes a fixed-time event-triggered anti-windup collaborative controller for a towing system consisting of an unactuated offshore platform and multiple tugs. Firstly, a fixed-time virtual controller is proposed to acquire required towing force for the platform to track expected trajectory. Subsequently, the required towing force is allocated as desired towline tensions by quadratic programming algorithm, and corresponding desired length of each towline is calculated through towline catenary model. Based on desired towline tensions and lengths, a fixed-time collaborative controller is constructed for tugs with following key components: the input saturation of tugs is approximated by a Gaussian error function; a fixed-time extended state observer is employed to rapidly estimate compound disturbances including saturation approximation errors; a novel dynamic threshold event-triggered mechanism is designed to decrease the control input update frequency while maintaining the convergence performance of entire control system. Finally, simulation results demonstrate the effectiveness of proposed control method.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100706"},"PeriodicalIF":3.9,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-01-01DOI: 10.1016/j.ijnaoe.2025.100710
Ruoling Zhou , Liu Yang , Ailong Fan , Qing Liu , Lei Wang , JunZhang Yang , Nikola Vladimir
With the advancement of global environmental protection policies and the transformation of energy structure, battery electric ships (BESs) are expected to enter a period of accelerated development. However, the associated risk factors are more complex than those of traditional ships, making it difficult for existing risk assessment approaches to fully capture emerging risks. This paper systematically identifies the key risk factors from four dimensions: seafarer, ship, environment and management, summarizes the risk assessment methods ranging from single-component failure analysis to overall ship safety evaluation, and examines corresponding assessment results and preventive measures. The findings show that seafarer and ship risks exert direct influences on ship safety and impose higher technical requirements, whereas environmental and management risks exert indirect effects. For single-component failures, differentiated assessment methods are recommended, such as process-based analyses for seafarer risks, component-focused approaches for batteries, motors, and electronic systems, and dynamic hazard identification for charging facilities and environmental factors. For overall ship safety, comprehensive risk assessment frameworks are suggested. Finally, targeted prevention measures are proposed for various risk categories, including optimization of battery design and enhancement of seafarer competencies. Current risk assessment for BESs faces challenges related to limited data, immature models, and insufficient regulations. Future efforts should focus on gradually accumulating accident cases and risk datasets, as well as developing quantitative assessment methods or models capable of capturing interdependencies among risks.
{"title":"Systematic review of battery electric ship safety: risk factors, assessment methods, and preventive measures","authors":"Ruoling Zhou , Liu Yang , Ailong Fan , Qing Liu , Lei Wang , JunZhang Yang , Nikola Vladimir","doi":"10.1016/j.ijnaoe.2025.100710","DOIUrl":"10.1016/j.ijnaoe.2025.100710","url":null,"abstract":"<div><div>With the advancement of global environmental protection policies and the transformation of energy structure, battery electric ships (BESs) are expected to enter a period of accelerated development. However, the associated risk factors are more complex than those of traditional ships, making it difficult for existing risk assessment approaches to fully capture emerging risks. This paper systematically identifies the key risk factors from four dimensions: seafarer, ship, environment and management, summarizes the risk assessment methods ranging from single-component failure analysis to overall ship safety evaluation, and examines corresponding assessment results and preventive measures. The findings show that seafarer and ship risks exert direct influences on ship safety and impose higher technical requirements, whereas environmental and management risks exert indirect effects. For single-component failures, differentiated assessment methods are recommended, such as process-based analyses for seafarer risks, component-focused approaches for batteries, motors, and electronic systems, and dynamic hazard identification for charging facilities and environmental factors. For overall ship safety, comprehensive risk assessment frameworks are suggested. Finally, targeted prevention measures are proposed for various risk categories, including optimization of battery design and enhancement of seafarer competencies. Current risk assessment for BESs faces challenges related to limited data, immature models, and insufficient regulations. Future efforts should focus on gradually accumulating accident cases and risk datasets, as well as developing quantitative assessment methods or models capable of capturing interdependencies among risks.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100710"},"PeriodicalIF":3.9,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145681453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-01-01DOI: 10.1016/j.ijnaoe.2025.100654
Qingya Zhang , Jing Xu , Baigong Wu , Qiuping Wang , Xingyu Wang , Zhenrui Zhang , Hong Zhou
Welding residual stress (WRS) seriously affects the fracture performance of welded structures made of high-strength steel (HSS). Nevertheless, the influence mechanism of WRS on fracture performance remains unclear. In this study, a thick weld of Q690 HSS is fabricated, and experiments are conducted to test the tensile performance of the base metal (BM), welded metal (WM), and the welded joint. The Gurson-Tvergaard-Needleman (GTN) parameters for the thick weld are identified through experimental data and numerical simulation. Using transverse residual stress (TRS) and welding defects as initial inputs, the ductile fracture behavior of the thick weld is predicted through the identified GTN damage model. When TRS and welding defects are taken into account, the crack distribution shifts from the BM to the main WM and the back HAZ. The higher tensile stress in the WM, combined with welding defects, significantly reduce the fracture strength by accelerating the void growth and coalescence process.
{"title":"Influence of transverse residual stress and welding defect on fracture performance of thick weld based on GTN damage model","authors":"Qingya Zhang , Jing Xu , Baigong Wu , Qiuping Wang , Xingyu Wang , Zhenrui Zhang , Hong Zhou","doi":"10.1016/j.ijnaoe.2025.100654","DOIUrl":"10.1016/j.ijnaoe.2025.100654","url":null,"abstract":"<div><div>Welding residual stress (WRS) seriously affects the fracture performance of welded structures made of high-strength steel (HSS). Nevertheless, the influence mechanism of WRS on fracture performance remains unclear. In this study, a thick weld of Q690 HSS is fabricated, and experiments are conducted to test the tensile performance of the base metal (BM), welded metal (WM), and the welded joint. The Gurson-Tvergaard-Needleman (GTN) parameters for the thick weld are identified through experimental data and numerical simulation. Using transverse residual stress (TRS) and welding defects as initial inputs, the ductile fracture behavior of the thick weld is predicted through the identified GTN damage model. When TRS and welding defects are taken into account, the crack distribution shifts from the BM to the main WM and the back HAZ. The higher tensile stress in the WM, combined with welding defects, significantly reduce the fracture strength by accelerating the void growth and coalescence process.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100654"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-01DOI: 10.1016/j.ijnaoe.2024.100642
Lin Ma , Dengkai Chen , Yanpu Yan , Weilan An
Submarine compartment layout design is a multi-objective optimization problem, which needs to consider the mutual position, passage relationship, comfort, convenience, and other aspects between compartments. Based on the characteristics of submarine living cabin layouts, this paper introduces a fuzzy evaluation method to comprehensively analyze the functional adjacency and personnel circulation relationships between compartments. Moreover, combined with emergency evacuation requirements, the study established a double layer cabin layout optimization model and proposed a multi-population genetic algorithm for optimizing the layout of submarine living cabins. Simulation experiments were conducted using MATLAB software to validate the algorithm's effectiveness. A comparison was made between the multi-population genetic algorithm and the standard genetic algorithm. The results verify the feasibility of the proposed design method and its ability to effectively address the submarine compartment layout optimization problem, thereby improving the efficiency of compartment layout optimization design.
{"title":"An optimization design method for submarine cabins based on intelligent algorithms","authors":"Lin Ma , Dengkai Chen , Yanpu Yan , Weilan An","doi":"10.1016/j.ijnaoe.2024.100642","DOIUrl":"10.1016/j.ijnaoe.2024.100642","url":null,"abstract":"<div><div>Submarine compartment layout design is a multi-objective optimization problem, which needs to consider the mutual position, passage relationship, comfort, convenience, and other aspects between compartments. Based on the characteristics of submarine living cabin layouts, this paper introduces a fuzzy evaluation method to comprehensively analyze the functional adjacency and personnel circulation relationships between compartments. Moreover, combined with emergency evacuation requirements, the study established a double layer cabin layout optimization model and proposed a multi-population genetic algorithm for optimizing the layout of submarine living cabins. Simulation experiments were conducted using MATLAB software to validate the algorithm's effectiveness. A comparison was made between the multi-population genetic algorithm and the standard genetic algorithm. The results verify the feasibility of the proposed design method and its ability to effectively address the submarine compartment layout optimization problem, thereby improving the efficiency of compartment layout optimization design.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100642"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Planning safe and efficient routes for small ships inside the marina is essential. However, existing route planning methods have been primarily developed for commercial ships and, therefore, fail to adequately capture the unique navigational characteristics of small ships. To address this limitation, this study proposed a route planning method for small ships navigating inside the marina. The proposed method generated centerline charts based on a Voronoi diagram. Here, the Voronoi diagram was generated from the integrated nautical charts, which comprehensively account for various features inside the marina. Then, the A∗ algorithm was applied by incorporating water depth to plan the optimal route. Furthermore, postprocessing of the planned route was introduced to account for the dredged area and the port-to-port passing rules at marina entrances, including route smoothing. Finally, the proposed method was applied to a marina near the Miami region to evaluate its effectiveness. The results demonstrate that, unlike existing methods, the proposed method successfully considers water depth, dredged area, and port-to-port passing rules at marina entrances while also maintaining a safety distance from the shoreline, all within a short computation time. Accordingly, the proposed method is expected to enhance the safety and efficiency of small ships navigating inside the marina.
{"title":"A route planning method for small ships inside the marina","authors":"In-Chang Yeo , Myung-Il Roh , Dong-Guen Jeong , Jun-Sik Lee","doi":"10.1016/j.ijnaoe.2025.100684","DOIUrl":"10.1016/j.ijnaoe.2025.100684","url":null,"abstract":"<div><div>Planning safe and efficient routes for small ships inside the marina is essential. However, existing route planning methods have been primarily developed for commercial ships and, therefore, fail to adequately capture the unique navigational characteristics of small ships. To address this limitation, this study proposed a route planning method for small ships navigating inside the marina. The proposed method generated centerline charts based on a Voronoi diagram. Here, the Voronoi diagram was generated from the integrated nautical charts, which comprehensively account for various features inside the marina. Then, the A∗ algorithm was applied by incorporating water depth to plan the optimal route. Furthermore, postprocessing of the planned route was introduced to account for the dredged area and the port-to-port passing rules at marina entrances, including route smoothing. Finally, the proposed method was applied to a marina near the Miami region to evaluate its effectiveness. The results demonstrate that, unlike existing methods, the proposed method successfully considers water depth, dredged area, and port-to-port passing rules at marina entrances while also maintaining a safety distance from the shoreline, all within a short computation time. Accordingly, the proposed method is expected to enhance the safety and efficiency of small ships navigating inside the marina.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100684"},"PeriodicalIF":3.9,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144917860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-01-01DOI: 10.1016/j.ijnaoe.2025.100659
Jeongung Park , Gyubaek An
With increasing strength and thickness of steel plates, the susceptibility to brittle fracture also grows, primarily due to the reduction in toughness of both the base metal and the weld zone. To maintain structural integrity and mitigate fracture risks in thick, high-strength steels—especially in applications such as ship hulls—advanced design strategies and materials with enhanced brittle crack arrestability have been introduced. The arrest performance is typically assessed by determining the brittle crack arrestability value (Kca) through large-scale experimental methods. However, due to the high cost, time, and equipment demands of such tests, alternative approaches using small-scale specimens and numerical simulations have been actively investigated to estimate Kca more efficiently. This study establishes an analytical model by conducting a parametric investigation of the key factors influencing Kca determination. The analysis incorporates yield stress variations influenced by temperature gradients, strain rates, and thermal effects, considering Young's modulus and strain rate dependency. Additionally, the study examines the influence of crack-growth increments and the impact energy effect on brittle crack initiation (KIC). The reliability of the proposed model is validated by comparing its Kca predictions with experimental results obtained from the ESSO test.
{"title":"Finite-element analysis on the parameters influencing the brittle crack arrest in steel plates","authors":"Jeongung Park , Gyubaek An","doi":"10.1016/j.ijnaoe.2025.100659","DOIUrl":"10.1016/j.ijnaoe.2025.100659","url":null,"abstract":"<div><div>With increasing strength and thickness of steel plates, the susceptibility to brittle fracture also grows, primarily due to the reduction in toughness of both the base metal and the weld zone. To maintain structural integrity and mitigate fracture risks in thick, high-strength steels—especially in applications such as ship hulls—advanced design strategies and materials with enhanced brittle crack arrestability have been introduced. The arrest performance is typically assessed by determining the brittle crack arrestability value (Kca) through large-scale experimental methods. However, due to the high cost, time, and equipment demands of such tests, alternative approaches using small-scale specimens and numerical simulations have been actively investigated to estimate Kca more efficiently. This study establishes an analytical model by conducting a parametric investigation of the key factors influencing Kca determination. The analysis incorporates yield stress variations influenced by temperature gradients, strain rates, and thermal effects, considering Young's modulus and strain rate dependency. Additionally, the study examines the influence of crack-growth increments and the impact energy effect on brittle crack initiation (K<sub>IC</sub>). The reliability of the proposed model is validated by comparing its Kca predictions with experimental results obtained from the ESSO test.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100659"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-01-01DOI: 10.1016/j.ijnaoe.2023.100561
Minsung Chun , Jinyoung Kim , Kangho Kim , Daseul Jeong , Deokyeon Lee , Sungkuk Wi , Byeonghwa Kim , Cheonghak Kim , Chun-Sik Shim
The currently defined Safe Working Load (SWL) of the U-bolt has been determined excessively conservatively. To address this issue, this study conducted structural tests and numerical analysis on round type U-bolts of various sizes. The structural tests were conducted using a 2.5 MN actuator at the SURF R&D center, and the strain was measured through a uniaxial strain gage. The test showed the failure load greatly exceeded the design load with horizontal force. This necessitates a reevaluation and redefinition of load standards. Nonlinear numerical analysis was carried out, and these results were compared with the structural test results. When subjected to vertical loading, behavior was similar to uniaxial tension. On the other hand, using linear elastic analysis for determining SWL for horizontal loading was found to be irrational. A methodology was proposed for estimating the SWL of the U-bolt.
{"title":"A fundamental study on structural strength assessment of U-bolts for expanded application to shipbuilding and offshore piping systems","authors":"Minsung Chun , Jinyoung Kim , Kangho Kim , Daseul Jeong , Deokyeon Lee , Sungkuk Wi , Byeonghwa Kim , Cheonghak Kim , Chun-Sik Shim","doi":"10.1016/j.ijnaoe.2023.100561","DOIUrl":"10.1016/j.ijnaoe.2023.100561","url":null,"abstract":"<div><p>The currently defined Safe Working Load (SWL) of the U-bolt has been determined excessively conservatively. To address this issue, this study conducted structural tests and numerical analysis on round type U-bolts of various sizes. The structural tests were conducted using a 2.5 MN actuator at the SURF R&D center, and the strain was measured through a uniaxial strain gage. The test showed the failure load greatly exceeded the design load with horizontal force. This necessitates a reevaluation and redefinition of load standards. Nonlinear numerical analysis was carried out, and these results were compared with the structural test results. When subjected to vertical loading, behavior was similar to uniaxial tension. On the other hand, using linear elastic analysis for determining SWL for horizontal loading was found to be irrational. A methodology was proposed for estimating the SWL of the U-bolt.</p></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"16 ","pages":"Article 100561"},"PeriodicalIF":2.2,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S209267822300050X/pdfft?md5=51f5052d5c552a2bb1acd4642ed89d4d&pid=1-s2.0-S209267822300050X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138628399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-01DOI: 10.1016/j.ijnaoe.2023.100565
Lin Ke , Jinming Ye , Wei He
To assess the effectiveness of subgrid scale (SGS) models on the prediction results of unsteady loads and turbulent fluctuation of pumpjet propulsors equipped with both front and rear stators, a pumpjet propulsor computational model with attached parts at the model scale is developed using a fully structured mesh, and large eddy simulations are conducted. The computational results of the different SGS models are compared based on five aspects: open water characteristics, turbulence parameters, incoming turbulence spectrum, vortex structure, and fluctuating pressure. Their results are also compared with the experimental values, and the correlation between the internal flow characteristics of the pumpjet propulsor and the turbulent fluctuation is analyzed. According to the results, as regards the prediction of the open water performance of the pumpjet propulsor containing both front and rear stators, the overall trend obtained by the three subgrid models is similar, and the error between the values predicted by the SL model and the experimental ones is the smallest. At the same mesh level, the turbulent fluctuating scale obtained by the SL model is larger than that obtained by the WALE and DSL models, and the turbulent time scale obtained by the DSL model has the smallest fluctuation in the circumferential direction. Among the three SGS models, the turbulent fluctuating scale of the SL model is larger than those of the WALE and DSL models. The SL model exhibits the largest energy dissipation among the three SGS models, followed by the DSL model, while that of the WALE model is the smallest. In the WALE model, the leakage vortex at the top of the blade is the longest, followed by the DSL model, while it is the shortest in the SL model. In the WALE and DSL models, the fluctuating load fluctuates more in the transition region from the middle section to the trailing edge of the blade.
{"title":"Evaluation of subgrid scale models in turbulent large eddy simulations of pumpjet propulsor","authors":"Lin Ke , Jinming Ye , Wei He","doi":"10.1016/j.ijnaoe.2023.100565","DOIUrl":"10.1016/j.ijnaoe.2023.100565","url":null,"abstract":"<div><p>To assess the effectiveness of subgrid scale (SGS) models on the prediction results of unsteady loads and turbulent fluctuation of pumpjet propulsors equipped with both front and rear stators, a pumpjet propulsor computational model with attached parts at the model scale is developed using a fully structured mesh, and large eddy simulations are conducted. The computational results of the different SGS models are compared based on five aspects: open water characteristics, turbulence parameters, incoming turbulence spectrum, vortex structure, and fluctuating pressure. Their results are also compared with the experimental values, and the correlation between the internal flow characteristics of the pumpjet propulsor and the turbulent fluctuation is analyzed. According to the results, as regards the prediction of the open water performance of the pumpjet propulsor containing both front and rear stators, the overall trend obtained by the three subgrid models is similar, and the error between the values predicted by the SL model and the experimental ones is the smallest. At the same mesh level, the turbulent fluctuating scale obtained by the SL model is larger than that obtained by the WALE and DSL models, and the turbulent time scale obtained by the DSL model has the smallest fluctuation in the circumferential direction. Among the three SGS models, the turbulent fluctuating scale of the SL model is larger than those of the WALE and DSL models. The SL model exhibits the largest energy dissipation among the three SGS models, followed by the DSL model, while that of the WALE model is the smallest. In the WALE model, the leakage vortex at the top of the blade is the longest, followed by the DSL model, while it is the shortest in the SL model. In the WALE and DSL models, the fluctuating load fluctuates more in the transition region from the middle section to the trailing edge of the blade.</p></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"16 ","pages":"Article 100565"},"PeriodicalIF":2.2,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2092678223000547/pdfft?md5=2377db61ed383f849c1b356aa654b2c1&pid=1-s2.0-S2092678223000547-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138743515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-01DOI: 10.1016/j.ijnaoe.2024.100620
Quang Khai Nguyen , Hyun Park , Kwang Hyo Jung , Jae Heon Kwon , Gang Nam Lee
The Polymer Electrolyte Membrane Fuel Cell (PEMFC) has been widely developed in the shipping sector, prompting the need to accurately understand its characteristics under various operating conditions and load variations. This study presents an experimental investigation into the steady-state and dynamic characteristics of a 1 kW water-cooled PEMFC stack, aiming to optimize reactant consumption and to assess the PEMFC voltage response under varying load conditions. In the steady-state tests, experiments were conducted at three different stoichiometries of hydrogen and air to evaluate the effect of stoichiometry on PEMFC efficiency. The results showed that the electrical efficiency improved by 10% at lower hydrogen stoichiometry (1.2) compared to the manufacturer's recommended values (1.6). In the dynamic tests, the behaviors of undershoot voltage and open circuit voltage (OCV) were examined using load-step and load-ramp conditions. Results showed that the undershoot voltage could be reduced either by narrowing the load step size and ramp rate or by implementing a reactant supply strategy, which increasing the gas flow rates before increasing the current. A consistent 0.55 V recovery was observed at the OCV after 10 s, regardless of the step sizes or ramp rates of load, indicating that the PEMFC was in good state of health after dynamic load conditions. OCV can serve as an effective diagnostic tool for assessing PEMFC health.
{"title":"Experimental study of the steady-state and dynamic characteristics of 1 kW water-cooled PEMFC","authors":"Quang Khai Nguyen , Hyun Park , Kwang Hyo Jung , Jae Heon Kwon , Gang Nam Lee","doi":"10.1016/j.ijnaoe.2024.100620","DOIUrl":"10.1016/j.ijnaoe.2024.100620","url":null,"abstract":"<div><div>The Polymer Electrolyte Membrane Fuel Cell (PEMFC) has been widely developed in the shipping sector, prompting the need to accurately understand its characteristics under various operating conditions and load variations. This study presents an experimental investigation into the steady-state and dynamic characteristics of a 1 kW water-cooled PEMFC stack, aiming to optimize reactant consumption and to assess the PEMFC voltage response under varying load conditions. In the steady-state tests, experiments were conducted at three different stoichiometries of hydrogen and air to evaluate the effect of stoichiometry on PEMFC efficiency. The results showed that the electrical efficiency improved by 10% at lower hydrogen stoichiometry (1.2) compared to the manufacturer's recommended values (1.6). In the dynamic tests, the behaviors of undershoot voltage and open circuit voltage (OCV) were examined using load-step and load-ramp conditions. Results showed that the undershoot voltage could be reduced either by narrowing the load step size and ramp rate or by implementing a reactant supply strategy, which increasing the gas flow rates before increasing the current. A consistent 0.55 V recovery was observed at the OCV after 10 s, regardless of the step sizes or ramp rates of load, indicating that the PEMFC was in good state of health after dynamic load conditions. OCV can serve as an effective diagnostic tool for assessing PEMFC health.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"16 ","pages":"Article 100620"},"PeriodicalIF":2.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-01DOI: 10.1016/j.ijnaoe.2024.100586
Donghun Yu , Myung-Il Roh
With the increasing size of ships and increasing demand for autonomous navigation, ensuring ship safety is not the only concern; the efficiency of anti-collision technology should be enhanced. In this paper, we propose a novel hybrid anti-collision path planning method called VO-PATH. This method combines the advantages of the Velocity Obstacle (VO) algorithm, which guarantees anti-collision for autonomous ships, with the A* algorithm, which is known for its capacity to optimize paths. To assess the effectiveness of the proposed method, we conducted anti-collision simulations for both single- and multiple-encounter scenarios, all of which adhered to COLREGs-defined avoidance obligations. Furthermore, we evaluated the performance of the proposed method by comparing its results with those obtained using conventional VO and A* algorithms. The findings indicate that the proposed method is superior to the A* algorithm in terms of steering away from collisions in complex multiple-encounter scenarios. Additionally, the proposed method significantly reduces the distance traveled by the ship to avoid potential collisions, with improvements of up to approximately 6.6% compared with alternative algorithms. We expect that this reduction will enhance safety and provide a more efficient anti-collision path.
{"title":"Method for anti-collision path planning using velocity obstacle and A* algorithms for maritime autonomous surface ship","authors":"Donghun Yu , Myung-Il Roh","doi":"10.1016/j.ijnaoe.2024.100586","DOIUrl":"10.1016/j.ijnaoe.2024.100586","url":null,"abstract":"<div><p>With the increasing size of ships and increasing demand for autonomous navigation, ensuring ship safety is not the only concern; the efficiency of anti-collision technology should be enhanced. In this paper, we propose a novel hybrid anti-collision path planning method called VO-PATH. This method combines the advantages of the Velocity Obstacle (VO) algorithm, which guarantees anti-collision for autonomous ships, with the A* algorithm, which is known for its capacity to optimize paths. To assess the effectiveness of the proposed method, we conducted anti-collision simulations for both single- and multiple-encounter scenarios, all of which adhered to COLREGs-defined avoidance obligations. Furthermore, we evaluated the performance of the proposed method by comparing its results with those obtained using conventional VO and A* algorithms. The findings indicate that the proposed method is superior to the A* algorithm in terms of steering away from collisions in complex multiple-encounter scenarios. Additionally, the proposed method significantly reduces the distance traveled by the ship to avoid potential collisions, with improvements of up to approximately 6.6% compared with alternative algorithms. We expect that this reduction will enhance safety and provide a more efficient anti-collision path.</p></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"16 ","pages":"Article 100586"},"PeriodicalIF":2.2,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2092678224000050/pdfft?md5=c4b71b1ddb3c2008785dc47e96c71e60&pid=1-s2.0-S2092678224000050-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139689261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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