Pub Date : 2025-01-01DOI: 10.1016/j.ijnaoe.2024.100641
Jooho Lee, Seonhong Kim, Jihwan Shin, Jaemoon Yoon, Jinheong Ahn, Minjae Kim
Development of submarine and its safe operational envelope requires an understanding of motion characteristics including emergency rising motion. In this study, the emergency rising motion is investigated using submarine free-running model equipped with ballast systems. The emergency rising test was conducted according to the initial vehicle speed, yaw rate, depth, ballast water discharge ratio and time interval between bow and stern ballast systems. Experimental results reveal that the maximum pitch angle before surface is affected by initial velocity and the operation conditions of ballast systems. In addition, excessive roll occurs after the surface when the submarine passes through the water surface at a negative pitch angle. Furthermore, the system parameters that comprise the emergency rising model are estimated using the collected test data. The identified model is verified by comparing emergency rising simulation with the free-running model test results.
{"title":"Experiment and modeling of submarine emergency rising motion using free-running model","authors":"Jooho Lee, Seonhong Kim, Jihwan Shin, Jaemoon Yoon, Jinheong Ahn, Minjae Kim","doi":"10.1016/j.ijnaoe.2024.100641","DOIUrl":"10.1016/j.ijnaoe.2024.100641","url":null,"abstract":"<div><div>Development of submarine and its safe operational envelope requires an understanding of motion characteristics including emergency rising motion. In this study, the emergency rising motion is investigated using submarine free-running model equipped with ballast systems. The emergency rising test was conducted according to the initial vehicle speed, yaw rate, depth, ballast water discharge ratio and time interval between bow and stern ballast systems. Experimental results reveal that the maximum pitch angle before surface is affected by initial velocity and the operation conditions of ballast systems. In addition, excessive roll occurs after the surface when the submarine passes through the water surface at a negative pitch angle. Furthermore, the system parameters that comprise the emergency rising model are estimated using the collected test data. The identified model is verified by comparing emergency rising simulation with the free-running model test results.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100641"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164720","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.2025.100643
Yun-jae Kim , Jin Seok Lim , Hae Jong Kim , Sung-Woong Choi
In the present study, technical challenges and their corresponding solutions for each type of foundation—gravity-based, monopile, jacket, tripod, and suction bucket—used in wind turbines were addressed with consideration to different water depths. Along with presenting challenges and their solutions for each foundation, the present study proposed optimizing solutions and methods for addressing these challenges, including numerical approaches and empirical methods derived from field testing. These include enhancing structural stability, improving installation efficiency, and utilizing advanced structural analysis techniques to predict and mitigate environmental impacts. Finally, research cases demonstrating improvements in foundations through shape modifications are summarized. This paper focuses on addressing and proposing an optimal design approach to achieve cost reduction, improved stiffness, and weight minimization. Notably, hybrid foundations incorporating friction wheels achieved a 300% increase in ultimate bearing capacity, while optimization techniques accounting for environmental loads resulted in approximately a 38.24% reduction in foundation weight.
{"title":"A comprehensive review of foundation designs for fixed offshore wind turbines","authors":"Yun-jae Kim , Jin Seok Lim , Hae Jong Kim , Sung-Woong Choi","doi":"10.1016/j.ijnaoe.2025.100643","DOIUrl":"10.1016/j.ijnaoe.2025.100643","url":null,"abstract":"<div><div>In the present study, technical challenges and their corresponding solutions for each type of foundation—gravity-based, monopile, jacket, tripod, and suction bucket—used in wind turbines were addressed with consideration to different water depths. Along with presenting challenges and their solutions for each foundation, the present study proposed optimizing solutions and methods for addressing these challenges, including numerical approaches and empirical methods derived from field testing. These include enhancing structural stability, improving installation efficiency, and utilizing advanced structural analysis techniques to predict and mitigate environmental impacts. Finally, research cases demonstrating improvements in foundations through shape modifications are summarized. This paper focuses on addressing and proposing an optimal design approach to achieve cost reduction, improved stiffness, and weight minimization. Notably, hybrid foundations incorporating friction wheels achieved a 300% increase in ultimate bearing capacity, while optimization techniques accounting for environmental loads resulted in approximately a 38.24% reduction in foundation weight.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100643"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474584","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.2025.100644
Son Tung Vu , Thai Duong Nguyen , Hai Van Dang , Van Suong Nguyen
This paper develops a robust controller for automatic ship berthing subjected to actuator faults, input saturation, modeling uncertainties, and external disturbances. First, sliding mode control (SMC) is used as a core controller to provide robust features for the ship berthing system. Second, fault-tolerant control (FTC) is combined with the controller to face the actuator faults. Third, the radial basis function (RBF) neural network is employed to approximate the modeling uncertainties while the effect of external disturbances is compensated by an adaptive control technique. In addition, an anti-saturation auxiliary system is conducted to deal with the input saturation for physical limitations of the actuators. Finally, numerical simulation and comparison of the results with the other control approaches are carried out to highlight the advantages of the proposed controller.
{"title":"Adaptive neural network fault-tolerant sliding mode control for ship berthing with actuator faults and input saturation","authors":"Son Tung Vu , Thai Duong Nguyen , Hai Van Dang , Van Suong Nguyen","doi":"10.1016/j.ijnaoe.2025.100644","DOIUrl":"10.1016/j.ijnaoe.2025.100644","url":null,"abstract":"<div><div>This paper develops a robust controller for automatic ship berthing subjected to actuator faults, input saturation, modeling uncertainties, and external disturbances. First, sliding mode control (SMC) is used as a core controller to provide robust features for the ship berthing system. Second, fault-tolerant control (FTC) is combined with the controller to face the actuator faults. Third, the radial basis function (RBF) neural network is employed to approximate the modeling uncertainties while the effect of external disturbances is compensated by an adaptive control technique. In addition, an anti-saturation auxiliary system is conducted to deal with the input saturation for physical limitations of the actuators. Finally, numerical simulation and comparison of the results with the other control approaches are carried out to highlight the advantages of the proposed controller.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100644"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164718","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.2025.100646
Jiseung Lee , Wonjun Jo , Junseok Seo , Gyubaek An
This study evaluates the effect of notch shape on the fracture toughness of a 500 MPa base material designed for liquefied carbon dioxide storage tanks. This study specifically focuses on assessing the crack tip opening displacement (CTOD) values for different notch shapes, including fatigue pre-cracks (R = 0.025 mm) and electrical discharge machining (EDM) notches (R = 0.07 mm and R = 0.15 mm). CTOD tests were conducted over a temperature range of −55 °C to −140 °C. The results revealed that as the notch radius increased, the degree of stress concentration decreased, leading to an increase in fracture toughness. In temperature-dependent tests, CTOD values consistently decreased as the temperature decreased, with EDM notches exhibiting a lower rate of fracture toughness reduction compared to fatigue pre-cracks, which is attributed to differences in the degree of stress concentration. Scanning electron microscopy analysis of the fracture surfaces revealed the reason for significant differences in CTOD values and fracture behaviors between fatigue pre-crack and EDM notches, particularly at −140 °C, a temperature below the ductile to brittle transition temperature. This study suggests that EDM notches, especially with radii of 0.07 mm and 0.15 mm, can effectively replace fatigue pre-cracks in CTOD evaluations, particularly at temperatures above the transition temperature, offering a more efficient method for assessing fracture toughness in cryogenic environments.
{"title":"Effect of notch shape on the fracture toughness behavior","authors":"Jiseung Lee , Wonjun Jo , Junseok Seo , Gyubaek An","doi":"10.1016/j.ijnaoe.2025.100646","DOIUrl":"10.1016/j.ijnaoe.2025.100646","url":null,"abstract":"<div><div>This study evaluates the effect of notch shape on the fracture toughness of a 500 MPa base material designed for liquefied carbon dioxide storage tanks. This study specifically focuses on assessing the crack tip opening displacement (CTOD) values for different notch shapes, including fatigue pre-cracks (R = 0.025 mm) and electrical discharge machining (EDM) notches (R = 0.07 mm and R = 0.15 mm). CTOD tests were conducted over a temperature range of −55 °C to −140 °C. The results revealed that as the notch radius increased, the degree of stress concentration decreased, leading to an increase in fracture toughness. In temperature-dependent tests, CTOD values consistently decreased as the temperature decreased, with EDM notches exhibiting a lower rate of fracture toughness reduction compared to fatigue pre-cracks, which is attributed to differences in the degree of stress concentration. Scanning electron microscopy analysis of the fracture surfaces revealed the reason for significant differences in CTOD values and fracture behaviors between fatigue pre-crack and EDM notches, particularly at −140 °C, a temperature below the ductile to brittle transition temperature. This study suggests that EDM notches, especially with radii of 0.07 mm and 0.15 mm, can effectively replace fatigue pre-cracks in CTOD evaluations, particularly at temperatures above the transition temperature, offering a more efficient method for assessing fracture toughness in cryogenic environments.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100646"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348296","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.2025.100655
Dong-Jin Kim, Haeseong Ahn, Dong Jin Yeo
In this study, powering and manoeuvring performance of a twin-screw surface combatant, ONR tumblehome (ONRT), are estimated through towing tank captive model tests, and influences of appendage dimensions on its course-stabilities and manoeuvres are investigated by system-based simulation techniques. At first, resistance and propulsion tests are carried out at Froude numbers up to 0.4 in the towing tank of Korea Research Institute of Ships and Ocean Engineering (KRISO) so that its full-scale powering performance can be considered in the present simulation model. In particular, the residuary resistance is significantly affected by patterns of hull generated waves. Secondly, horizontal planar motion mechanism (HPMM) tests are performed to derive hydrodynamic coefficients in surge, sway, and yaw directions. By using 3-DoF modular-type models, turn and zig-zag manoeuvres are simulated, and simulations are validated with existing benchmark free-run model tests. Sway-yaw coupled linear whole ship models are also established in order to assess a straight-line stability of a rudder-fixed ONRT whole ship. Linear hydrodynamic coefficients are decomposed into hull and appendage components so that influences of appendage dimensions on ship manoeuvres can be analyzed in more detail. When the rudder area is enlarged or reduced, the coefficient and the location of a centerline skeg are redesigned under the constraint straight-line stabilities are identical. For one original ONRT and two modified ships, turn and zig-zag manoeuvres are simulated by linear whole ship models. Even though straight-line stabilities are identical, the turning diameter is decreased while zig-zag overshoot angles are increased with increasing rudder area. To ensure sufficient manoeuvrabilities of such a twin-screw ship, careful attentions should be paid to design of a centerline skeg and rudders.
{"title":"Horizontal plane course-stability and manoeuvres of a twin-screw surface combatant depending on appendage dimensions","authors":"Dong-Jin Kim, Haeseong Ahn, Dong Jin Yeo","doi":"10.1016/j.ijnaoe.2025.100655","DOIUrl":"10.1016/j.ijnaoe.2025.100655","url":null,"abstract":"<div><div>In this study, powering and manoeuvring performance of a twin-screw surface combatant, ONR tumblehome (ONRT), are estimated through towing tank captive model tests, and influences of appendage dimensions on its course-stabilities and manoeuvres are investigated by system-based simulation techniques. At first, resistance and propulsion tests are carried out at Froude numbers up to 0.4 in the towing tank of Korea Research Institute of Ships and Ocean Engineering (KRISO) so that its full-scale powering performance can be considered in the present simulation model. In particular, the residuary resistance is significantly affected by patterns of hull generated waves. Secondly, horizontal planar motion mechanism (HPMM) tests are performed to derive hydrodynamic coefficients in surge, sway, and yaw directions. By using 3-DoF modular-type models, turn and zig-zag manoeuvres are simulated, and simulations are validated with existing benchmark free-run model tests. Sway-yaw coupled linear whole ship models are also established in order to assess a straight-line stability of a rudder-fixed ONRT whole ship. Linear hydrodynamic coefficients are decomposed into hull and appendage components so that influences of appendage dimensions on ship manoeuvres can be analyzed in more detail. When the rudder area is enlarged or reduced, the coefficient and the location of a centerline skeg are redesigned under the constraint straight-line stabilities are identical. For one original ONRT and two modified ships, turn and zig-zag manoeuvres are simulated by linear whole ship models. Even though straight-line stabilities are identical, the turning diameter is decreased while zig-zag overshoot angles are increased with increasing rudder area. To ensure sufficient manoeuvrabilities of such a twin-screw ship, careful attentions should be paid to design of a centerline skeg and rudders.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100655"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738100","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.2025.100652
Chang Sub Song , Jong-Ho Nam
Currently, the shipbuilding industry is experiencing a surge in orders due to the rising demand for eco-friendly ships, necessitating the optimal use of available resources for production. However, the production workforce has not fully recovered to the level required to meet these increased orders following large-scale industry restructuring. In particular, there is a shortage of highly skilled welders, and concerns are growing about the transfer of expertise due to an aging workforce and a lack of younger workers. Shipbuilders worldwide face similar challenges and are exploring various methods to transfer the tacit knowledge of skilled welders to less experienced workers, which has introduced unforeseen challenges. In this study, we develop a machine learning algorithm that suggests the optimal values of key welding variables for an AR-based welding training system designed to assist less skilled workers. We collected welding data from highly skilled workers using the FCAW (Flux-Cored Arc Welding) technique, which is commonly employed in the shipbuilding process. The welding variables that represent tacit knowledge were identified and trained using the Extra Trees Regressor model. Subsequently, a welding AR training system was implemented, allowing the trained model to guide users on the optimal values for welding variables. Finally, the effectiveness of this system in training welders was verified at a shipyard technical training center.
{"title":"Machine learning-based optimal value calculation for welding variables in AR training","authors":"Chang Sub Song , Jong-Ho Nam","doi":"10.1016/j.ijnaoe.2025.100652","DOIUrl":"10.1016/j.ijnaoe.2025.100652","url":null,"abstract":"<div><div>Currently, the shipbuilding industry is experiencing a surge in orders due to the rising demand for eco-friendly ships, necessitating the optimal use of available resources for production. However, the production workforce has not fully recovered to the level required to meet these increased orders following large-scale industry restructuring. In particular, there is a shortage of highly skilled welders, and concerns are growing about the transfer of expertise due to an aging workforce and a lack of younger workers. Shipbuilders worldwide face similar challenges and are exploring various methods to transfer the tacit knowledge of skilled welders to less experienced workers, which has introduced unforeseen challenges. In this study, we develop a machine learning algorithm that suggests the optimal values of key welding variables for an AR-based welding training system designed to assist less skilled workers. We collected welding data from highly skilled workers using the FCAW (Flux-Cored Arc Welding) technique, which is commonly employed in the shipbuilding process. The welding variables that represent tacit knowledge were identified and trained using the Extra Trees Regressor model. Subsequently, a welding AR training system was implemented, allowing the trained model to guide users on the optimal values for welding variables. Finally, the effectiveness of this system in training welders was verified at a shipyard technical training center.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100652"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519504","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.2025.100653
SeongMo Yeon, Chang Seop Kwon, Yoo-Chul Kim, Kwang Soo Kim, Yeon Gyu Kim, Yun Ho Kim, Hee Jin Kang
The study investigated a Flettner rotor performance on a hull, analyzing design modifications and wind profiles for a small catamaran which designed by KRISO for the K-Energy Observer platform was analyzed. The rotor mounted on the hull showed a nearly 48% performance degradation in lift coefficient compared to the standalone rotor due to the disturbed flow by the hull at spin ratios 3–4. Two design factors were examined to improve performance: foundation shape and bottom configuration of the rotor. A square foundation shape showed relatively better improvement but it was not significant. On the other hand, it was found that the rotating end plate significantly improved thrust, achieving up to 80% of the standalone rotor’s performance. Comparing uniform and Norwegian Petroleum Directorate (NPD) wind profiles, the NPD profile showed a 12% improvement due to stronger winds at the rotor’s upper section. The study also compared performance under different wind directions and it showed a 20% increase at 30° and 18% at 60° for the original configuration. In contrast, the rotating end plate configuration showed a 6% decrease at 30° but a 10% increase at 60°. However, overall performance improvement was observed in the rotating end plate configuration with increases of 12%, 34%, and 44% for 30°, 60° and 90° compared to the original configuration. Additionally, under a 5° inclined hull condition, performance decreased by 21% for the original configuration but only 13% for the rotating end plate configuration, which highlighted the design’s effectiveness in mitigating performance loss.
{"title":"Performance analysis of Flettner rotor considering Marine wind profile and ship installation using CFD","authors":"SeongMo Yeon, Chang Seop Kwon, Yoo-Chul Kim, Kwang Soo Kim, Yeon Gyu Kim, Yun Ho Kim, Hee Jin Kang","doi":"10.1016/j.ijnaoe.2025.100653","DOIUrl":"10.1016/j.ijnaoe.2025.100653","url":null,"abstract":"<div><div>The study investigated a Flettner rotor performance on a hull, analyzing design modifications and wind profiles for a small catamaran which designed by KRISO for the K-Energy Observer platform was analyzed. The rotor mounted on the hull showed a nearly 48% performance degradation in lift coefficient compared to the standalone rotor due to the disturbed flow by the hull at spin ratios 3–4. Two design factors were examined to improve performance: foundation shape and bottom configuration of the rotor. A square foundation shape showed relatively better improvement but it was not significant. On the other hand, it was found that the rotating end plate significantly improved thrust, achieving up to 80% of the standalone rotor’s performance. Comparing uniform and Norwegian Petroleum Directorate (NPD) wind profiles, the NPD profile showed a 12% improvement due to stronger winds at the rotor’s upper section. The study also compared performance under different wind directions and it showed a 20% increase at 30° and 18% at 60° for the original configuration. In contrast, the rotating end plate configuration showed a 6% decrease at 30° but a 10% increase at 60°. However, overall performance improvement was observed in the rotating end plate configuration with increases of 12%, 34%, and 44% for 30°, 60° and 90° compared to the original configuration. Additionally, under a 5° inclined hull condition, performance decreased by 21% for the original configuration but only 13% for the rotating end plate configuration, which highlighted the design’s effectiveness in mitigating performance loss.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100653"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735142","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.2024.100631
Yang Zhang , Se-Myong Chang , Deuk-Joon Yum
A planing craft is one of the most commonly used types for small high-performance vessels since it helps to mitigate the severe viscous friction between the ship hull and water. Therefore, it is essential to develop methods for quickly and accurately estimating the running attitude during the early design phase and in actual operational conditions. We propose the Extended Modified Logvinovich Model (EMLM) for water entry to address the flow separation problem when a wedge-shaped hull enters the free surface during motion. Utilizing a two-dimensional approximation, we analyzed the fundamental potential flow through mathematical techniques for unsteady flow. As a verification, we calculated the dynamic vertical force coefficient compared with CFD(computational fluid dynamics) based on BEM(boundary element method) and an analytic similarity solution, where the results demonstrated good agreement with experimental data for validation.
{"title":"The extended modified Logvinovich model: Application to the water entry of two-dimensional wedges","authors":"Yang Zhang , Se-Myong Chang , Deuk-Joon Yum","doi":"10.1016/j.ijnaoe.2024.100631","DOIUrl":"10.1016/j.ijnaoe.2024.100631","url":null,"abstract":"<div><div>A planing craft is one of the most commonly used types for small high-performance vessels since it helps to mitigate the severe viscous friction between the ship hull and water. Therefore, it is essential to develop methods for quickly and accurately estimating the running attitude during the early design phase and in actual operational conditions. We propose the Extended Modified Logvinovich Model (EMLM) for water entry to address the flow separation problem when a wedge-shaped hull enters the free surface during motion. Utilizing a two-dimensional approximation, we analyzed the fundamental potential flow through mathematical techniques for unsteady flow. As a verification, we calculated the dynamic vertical force coefficient compared with CFD(computational fluid dynamics) based on BEM(boundary element method) and an analytic similarity solution, where the results demonstrated good agreement with experimental data for validation.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100631"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164719","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.2025.100651
Maochun Wei , Keyu Chen , Fei Yan , Jikang Ma , Kaiming Liu , En Cheng
Environmental perception and object detection are pivotal research topics in the marine domain. The sea surface presents unique challenges, including harsh weather conditions, wave interference, and multi-scale targets, often resulting in suboptimal detection results. To address these issues, we present an innovative solution: the integration of the Efficient Scale Fusion Module (ESFM) into the advanced YOLO architecture, resulting in the enhanced model, YOLO-ESFM. The ESFM serves as both the backbone and detection head of the network, significantly improving performance compared to the baseline models in YOLOv5s, YOLOv7-tiny, and YOLOv7. Furthermore, to tackle the limitations of the CIOU in YOLOv7, we introduce an improved method, ZIOU, which has been rigorously evaluated and proven effective on the Sea Surface Target Dataset. Comparative studies demonstrate that YOLO-ESFM not only maintains efficiency in terms of parameters and FLOPs but also surpasses YOLOv7 in detection accuracy on both the Sea Surface Target Dataset and the PASCAL VOC 07+12 Dataset.
{"title":"YOLO-ESFM: A multi-scale YOLO algorithm for sea surface object detection","authors":"Maochun Wei , Keyu Chen , Fei Yan , Jikang Ma , Kaiming Liu , En Cheng","doi":"10.1016/j.ijnaoe.2025.100651","DOIUrl":"10.1016/j.ijnaoe.2025.100651","url":null,"abstract":"<div><div>Environmental perception and object detection are pivotal research topics in the marine domain. The sea surface presents unique challenges, including harsh weather conditions, wave interference, and multi-scale targets, often resulting in suboptimal detection results. To address these issues, we present an innovative solution: the integration of the Efficient Scale Fusion Module (ESFM) into the advanced YOLO architecture, resulting in the enhanced model, YOLO-ESFM. The ESFM serves as both the backbone and detection head of the network, significantly improving performance compared to the baseline models in YOLOv5s, YOLOv7-tiny, and YOLOv7. Furthermore, to tackle the limitations of the CIOU in YOLOv7, we introduce an improved method, ZIOU, which has been rigorously evaluated and proven effective on the Sea Surface Target Dataset. Comparative studies demonstrate that YOLO-ESFM not only maintains efficiency in terms of parameters and FLOPs but also surpasses YOLOv7 in detection accuracy on both the Sea Surface Target Dataset and the PASCAL VOC 07+12 Dataset.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100651"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610254","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.2025.100648
Ki-Seok Jung , Dong-Kun Lee
3D point clouds are a crucial data format for accurately capturing geometric information in large-scale industrial environments such as shipyards. Deep learning-based object detection technology using 3D point clouds enables automated production management and process optimization. However, the large volume characteristic of 3D point clouds remains a challenge due to the resources and time required for data processing and dataset construction. The large volume of 3D point clouds leads to excessive computational costs, storage demands, and time consumption during dataset construction and training. Therefore, it is necessary to appropriately reduce the dataset size for efficient utilization while ensuring object detection performance. This necessitates a study on dataset downsampling strategies that maintain optimal density and detection accuracy. In this study, an experimental dataset similar to the S3DIS (Stanford Large-Scale 3D Indoor Spaces) dataset was constructed. The density of the 3D point clouds was adjusted in five levels by reducing points per unit area by 20% increments. These datasets were applied to a deep learning architecture to analyze object detection accuracy. Subsequently, the findings were applied to a shipyard dataset to streamline large volume point clouds and evaluate detection performance, thereby assessing their practical applicability. The results demonstrated that reducing the experimental dataset density to approximately 20% still maintained object detection accuracy of around 95% IoU for key objects. This indicates that lightweight datasets can reduce processing resources and costs while preserving detection performance. Additionally, applying the approach to real shipyard datasets revealed that object detection was feasible with reduced data (approximately 4.6% of the raw data). This study provides a practical framework for constructing efficient deep learning models for object detection by downsampling datasets in large-scale industrial environments like shipyards. It is expected to contribute to the establishment of automated data management systems for production management and process efficiency enhancement. Further analysis is required to evaluate performance at extreme low densities (below 20%). Moreover, while this study employed simple downsampling techniques, future work should explore the performance of various downsampling methods to optimize detection accuracy.
三维点云是在造船厂等大型工业环境中准确捕获几何信息的关键数据格式。使用3D点云的基于深度学习的目标检测技术可实现自动化生产管理和流程优化。然而,由于数据处理和数据集构建所需的资源和时间,三维点云的大体积特征仍然是一个挑战。大量的三维点云导致数据集构建和训练过程中计算成本、存储需求和时间消耗过大。因此,在保证目标检测性能的同时,适当减小数据集的大小是很有必要的。这就需要研究保持最佳密度和检测精度的数据集降采样策略。本研究构建了一个类似于S3DIS (Stanford Large-Scale 3D Indoor Spaces)数据集的实验数据集。通过将单位面积上的点减少20%的增量,对三维点云的密度进行了五个级别的调整。这些数据集被应用于一个深度学习架构来分析目标检测的准确性。随后,将研究结果应用于造船厂数据集,以简化大体积点云并评估检测性能,从而评估其实际适用性。结果表明,将实验数据集密度降低到20%左右,对于关键目标仍然保持95% IoU左右的目标检测精度。这表明轻量级数据集可以在保持检测性能的同时减少处理资源和成本。此外,将该方法应用于真实造船厂数据集表明,减少数据(约为原始数据的4.6%)的目标检测是可行的。该研究为构建高效的深度学习模型提供了一个实用框架,该模型通过对造船厂等大型工业环境中的数据集进行下采样来进行目标检测。预期它将有助于建立自动化数据管理系统,以促进生产管理和提高过程效率。需要进一步分析以评估极低密度(低于20%)下的性能。此外,虽然本研究采用了简单的下采样技术,但未来的工作应该探索各种下采样方法的性能,以优化检测精度。
{"title":"Analysis of object detection accuracy based on the density of 3D point clouds for deep learning-based shipyard datasets","authors":"Ki-Seok Jung , Dong-Kun Lee","doi":"10.1016/j.ijnaoe.2025.100648","DOIUrl":"10.1016/j.ijnaoe.2025.100648","url":null,"abstract":"<div><div>3D point clouds are a crucial data format for accurately capturing geometric information in large-scale industrial environments such as shipyards. Deep learning-based object detection technology using 3D point clouds enables automated production management and process optimization. However, the large volume characteristic of 3D point clouds remains a challenge due to the resources and time required for data processing and dataset construction. The large volume of 3D point clouds leads to excessive computational costs, storage demands, and time consumption during dataset construction and training. Therefore, it is necessary to appropriately reduce the dataset size for efficient utilization while ensuring object detection performance. This necessitates a study on dataset downsampling strategies that maintain optimal density and detection accuracy. In this study, an experimental dataset similar to the S3DIS (Stanford Large-Scale 3D Indoor Spaces) dataset was constructed. The density of the 3D point clouds was adjusted in five levels by reducing points per unit area by 20% increments. These datasets were applied to a deep learning architecture to analyze object detection accuracy. Subsequently, the findings were applied to a shipyard dataset to streamline large volume point clouds and evaluate detection performance, thereby assessing their practical applicability. The results demonstrated that reducing the experimental dataset density to approximately 20% still maintained object detection accuracy of around 95% IoU for key objects. This indicates that lightweight datasets can reduce processing resources and costs while preserving detection performance. Additionally, applying the approach to real shipyard datasets revealed that object detection was feasible with reduced data (approximately 4.6% of the raw data). This study provides a practical framework for constructing efficient deep learning models for object detection by downsampling datasets in large-scale industrial environments like shipyards. It is expected to contribute to the establishment of automated data management systems for production management and process efficiency enhancement. Further analysis is required to evaluate performance at extreme low densities (below 20%). Moreover, while this study employed simple downsampling techniques, future work should explore the performance of various downsampling methods to optimize detection accuracy.</div></div>","PeriodicalId":14160,"journal":{"name":"International Journal of Naval Architecture and Ocean Engineering","volume":"17 ","pages":"Article 100648"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519503","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}