Until recently, the selection of ballast water treatment (BWT) systems was based on a predetermined set of criteria that did not include evaluations for system utilization due to lack of experience. The experience-building phase for the systems began, especially with the entry of the Ballast Water Management Convention into force. For effective assessment and decision-making, the evaluations of expert seafarers responsible for using ballast water treatment systems on-board ships are of paramount importance. This study was completed by evaluating the experience and evaluations of 50 expert seafarers (24 deck personnel and 26 engine personnel) working in a Turkish maritime company in three phases to contribute to the decision-making and system evaluation processes: 1- The failure reports written by the ship personnel of the maritime company were examined, and bilateral interviews with expert seafarers working on these tankers were held; 2- an online questionnaire was prepared and presented to seafarers; 3Analytic hierarchy process (AHP) was used to obtain a common perspective of the seafarers. In this study's first phase, 'ideal system characteristics' were determined. Based on these characteristics, an online questionnaire was prepared in the second phase of this study and presented to seafarers. In the third phase, a set of six criteria was developed, and the Analytic Hierarchy Process (AHP) was used to obtain the common perspective of 50 participants. Pairwise comparisons revealed that ‘Rare alarms and malfunctions’ was the most important criterion from the perspective of all seafarers and UV-type BWTSs were 1.76 times more preferable than the electrochemical (El-Chem) type BWTSs as a common approach.
{"title":"Evaluation of ballast water treatment systems from the perspective of expert seafarers' ship experiences","authors":"Mevlüt Yilmaz, Ceren Bilgin Güney","doi":"10.21278/brod74407","DOIUrl":"https://doi.org/10.21278/brod74407","url":null,"abstract":"Until recently, the selection of ballast water treatment (BWT) systems was based on a predetermined set of criteria that did not include evaluations for system utilization due to lack of experience. The experience-building phase for the systems began, especially with the entry of the Ballast Water Management Convention into force. For effective assessment and decision-making, the evaluations of expert seafarers responsible for using ballast water treatment systems on-board ships are of paramount importance. This study was completed by evaluating the experience and evaluations of 50 expert seafarers (24 deck personnel and 26 engine personnel) working in a Turkish maritime company in three phases to contribute to the decision-making and system evaluation processes: 1- The failure reports written by the ship personnel of the maritime company were examined, and bilateral interviews with expert seafarers working on these tankers were held; 2- an online questionnaire was prepared and presented to seafarers; 3Analytic hierarchy process (AHP) was used to obtain a common perspective of the seafarers. In this study's first phase, 'ideal system characteristics' were determined. Based on these characteristics, an online questionnaire was prepared in the second phase of this study and presented to seafarers. In the third phase, a set of six criteria was developed, and the Analytic Hierarchy Process (AHP) was used to obtain the common perspective of 50 participants. Pairwise comparisons revealed that ‘Rare alarms and malfunctions’ was the most important criterion from the perspective of all seafarers and UV-type BWTSs were 1.76 times more preferable than the electrochemical (El-Chem) type BWTSs as a common approach.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135427544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hong Shi, Rentong Zheng, Qianwei Zhang, Jie Yuan, Rui Wang, Mengmeng Cheng, Yitao Zou
The high-temperature exhaust gases and the hot surfaces of the ejector device in marine gas turbines generate significant levels of infrared radiation. An appropriate nozzle structure can effectively lower the exhaust gas temperature and reduce the high-temperature radiation surface area, thereby minimizing external infrared radiation. In this study, a numerical simulation of the nozzle structure in the ejector device was conducted using computational fluid dynamics (CFD) methods. By investigating the orthogonal combinations of nozzle inclination angles and the number of nozzles, the temperature distribution and flow characteristics under different operating conditions were analysed. The results showed that as the nozzle inclination angle increased, the entrainment coefficient (Ce) and the temperature ratio at the inlet and outlet (Rt) initially improved but then worsened. Simultaneously, the pressure loss coefficient (Cpl) increased with the inclination angle. The CRITIC weight method was employed to objectively allocate weights to Rt, Ce, and Cpl, determining the optimal solution. The results indicated that Rt and Cpl had significant and similar weights. The optimal solution was found in Case 10 (α = 5°, x = 4), with corresponding evaluation indices of Ce=2.38, Cpl=11.45, and =0.68. This study's findings are of great importance for enhancing the performance of marine gas turbines and reducing external infrared radiation.
{"title":"Numerical investigation of multi-nozzle ejector device with inclined nozzles for marine gas turbine","authors":"Hong Shi, Rentong Zheng, Qianwei Zhang, Jie Yuan, Rui Wang, Mengmeng Cheng, Yitao Zou","doi":"10.21278/brod74401","DOIUrl":"https://doi.org/10.21278/brod74401","url":null,"abstract":"The high-temperature exhaust gases and the hot surfaces of the ejector device in marine gas turbines generate significant levels of infrared radiation. An appropriate nozzle structure can effectively lower the exhaust gas temperature and reduce the high-temperature radiation surface area, thereby minimizing external infrared radiation. In this study, a numerical simulation of the nozzle structure in the ejector device was conducted using computational fluid dynamics (CFD) methods. By investigating the orthogonal combinations of nozzle inclination angles and the number of nozzles, the temperature distribution and flow characteristics under different operating conditions were analysed. The results showed that as the nozzle inclination angle increased, the entrainment coefficient (Ce) and the temperature ratio at the inlet and outlet (Rt) initially improved but then worsened. Simultaneously, the pressure loss coefficient (Cpl) increased with the inclination angle. The CRITIC weight method was employed to objectively allocate weights to Rt, Ce, and Cpl, determining the optimal solution. The results indicated that Rt and Cpl had significant and similar weights. The optimal solution was found in Case 10 (α = 5°, x = 4), with corresponding evaluation indices of Ce=2.38, Cpl=11.45, and =0.68. This study's findings are of great importance for enhancing the performance of marine gas turbines and reducing external infrared radiation.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42531356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shipbuilding is acknowledged as an uncertain, complex, and unique industrial effort that yields massive products consisting of numerous parts and is vulnerable to unexpected events. The industry is also dominated by customer requirements through designs tailor-made for a specific ship. Planning in shipbuilding is therefore considered a formidable process. Consequently, many studies have been conducted to develop a planning framework for the industry to efficiently handle planning process. Yet none of these studies are deemed substantial enough to be regarded as holistic, straightforward, well-accepted, and compatible with the nature of shipbuilding. This study is therefore an important contribution by presenting a novel, hybrid, and integrated general-purpose planning framework applicable to all shipbuilding processes. The novel method exploits historical ship construction scheduling data, synthesizing hierarchical planning, dynamic scheduling, and discrete-event simulation, which is validated through an empirical study in this paper.
{"title":"A novel approach for planning of shipbuilding processes","authors":"Aytek Gungor, Y. Unsan, B. Barlas","doi":"10.21278/brod74402","DOIUrl":"https://doi.org/10.21278/brod74402","url":null,"abstract":"Shipbuilding is acknowledged as an uncertain, complex, and unique industrial effort that yields massive products consisting of numerous parts and is vulnerable to unexpected events. The industry is also dominated by customer requirements through designs tailor-made for a specific ship. Planning in shipbuilding is therefore considered a formidable process. Consequently, many studies have been conducted to develop a planning framework for the industry to efficiently handle planning process. Yet none of these studies are deemed substantial enough to be regarded as holistic, straightforward, well-accepted, and compatible with the nature of shipbuilding. This study is therefore an important contribution by presenting a novel, hybrid, and integrated general-purpose planning framework applicable to all shipbuilding processes. The novel method exploits historical ship construction scheduling data, synthesizing hierarchical planning, dynamic scheduling, and discrete-event simulation, which is validated through an empirical study in this paper.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42457309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on combing the concept and development of intelligent ship, this paper brings forward the summary and classification of intelligent ships proposed by different institutions, and the main classification schemes are compared accordingly. Then one of these classification schemes is selected to study what are the key navigational risks under each grading level, with a detailed analysis of these risk factors. Finally, the index system of navigational risk factors for intelligent ships under different classification standards is constructed to lay a foundation for a further study of intelligent ship safe navigation, and at the same time avoid some risk factors in advance for the maritime management department, ship management companies, and ship design and research institutes.
{"title":"Research on classification and navigational risk factors of intelligent ship","authors":"Wenjun Zhang, Yingjun Zhang","doi":"10.21278/brod74406","DOIUrl":"https://doi.org/10.21278/brod74406","url":null,"abstract":"Based on combing the concept and development of intelligent ship, this paper brings forward the summary and classification of intelligent ships proposed by different institutions, and the main classification schemes are compared accordingly. Then one of these classification schemes is selected to study what are the key navigational risks under each grading level, with a detailed analysis of these risk factors. Finally, the index system of navigational risk factors for intelligent ships under different classification standards is constructed to lay a foundation for a further study of intelligent ship safe navigation, and at the same time avoid some risk factors in advance for the maritime management department, ship management companies, and ship design and research institutes.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135349178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel quantitative analysis employing the Principal Component Analysis (PCA) of containership traffic in the Black Sea from 2018 to 2021 is performed. The study uses a matrix covering five ship size classes from A to E for four years of operation, from 2018 to 2021, accounting for ship traffic, CO2, fuel consumption (FC), shipping intensity, and eco and traffic efficiency. Only the first two principal factors are analysed because of their total variation weight. Shipping intensity, FC intensity, and CO2 intensity plays a significant role in the first factor, while Eco efficiency, FC efficiency, and Traffic efficiency are considered for the second factor. Notably, the set of parameters pertains to time and is strongly associated with DWT. Two principal components were identified, F1 and F2, where F1 integrates efficiency and intensity. At the same time, F2 separates the intensity from the efficiency conditional on the ship size and the year of operations. In the principal component F1 the activities of ships A and C differ from B, D and E, separating more efficiently from less efficiently used ships, and in F2, the activities of class sizes of ships C and D and E contrast A and B ships, distinguishing the big-size class ships from small ones. It was concluded that the most intensively used ships are the ship size classes C and D, and the most efficient are ship size classes A and B. The most intensive use of the ships was in 2020, followed by 2021, and the most efficient were in 2018, 2019. Based on the ship activities and using the Within-class variance, ships are grouped into two clusters of similar activities, where the first one, with lower variance and more homogeneous, includes only the ship size class A. The second one with a relatively large variance consists of the rest size of the ships. Linear relationships considering the intensity and efficiency are derived as a function of the main variables, where the factor loading represents the variable’s coefficient, given as a relative weight to any factor.
{"title":"Principal component analysis of containership traffic in the Black Sea","authors":"Y. Garbatov, P. Georgiev","doi":"10.21278/brod74404","DOIUrl":"https://doi.org/10.21278/brod74404","url":null,"abstract":"A novel quantitative analysis employing the Principal Component Analysis (PCA) of containership traffic in the Black Sea from 2018 to 2021 is performed. The study uses a matrix covering five ship size classes from A to E for four years of operation, from 2018 to 2021, accounting for ship traffic, CO2, fuel consumption (FC), shipping intensity, and eco and traffic efficiency. Only the first two principal factors are analysed because of their total variation weight. Shipping intensity, FC intensity, and CO2 intensity plays a significant role in the first factor, while Eco efficiency, FC efficiency, and Traffic efficiency are considered for the second factor. Notably, the set of parameters pertains to time and is strongly associated with DWT. Two principal components were identified, F1 and F2, where F1 integrates efficiency and intensity. At the same time, F2 separates the intensity from the efficiency conditional on the ship size and the year of operations. In the principal component F1 the activities of ships A and C differ from B, D and E, separating more efficiently from less efficiently used ships, and in F2, the activities of class sizes of ships C and D and E contrast A and B ships, distinguishing the big-size class ships from small ones. It was concluded that the most intensively used ships are the ship size classes C and D, and the most efficient are ship size classes A and B. The most intensive use of the ships was in 2020, followed by 2021, and the most efficient were in 2018, 2019. Based on the ship activities and using the Within-class variance, ships are grouped into two clusters of similar activities, where the first one, with lower variance and more homogeneous, includes only the ship size class A. The second one with a relatively large variance consists of the rest size of the ships. Linear relationships considering the intensity and efficiency are derived as a function of the main variables, where the factor loading represents the variable’s coefficient, given as a relative weight to any factor.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48615509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sailing in oblique stern waves causes a ship to make sharp turns and uncontrollable course deviation, which is accompanied by a large heel and sometimes leads to capsizing. Studying the control algorithm in oblique stern waves is imperative because an excellent controller scheme can improve the ship’s course-keeping stability. This paper uses the Maneuvering Modelling Group (MMG) method based on hydrodynamic derivatives and the Computational Fluid Dynamics (CFD)-based self-navigation simulation to simulate ship navigation in waves. This study examines the effect of proportion-integral-derivative (PID) controller schemes on the stability of course maintenance based on hydrodynamic derivatives and 3DOF MMG methods. Then, the optimized PID control parameters are used to simulate the ship’s 6DOF self-propulsion navigation in oblique waves using the CFD method. The nonlinear phenomena during the process, such as side-hull emergency, slamming, and green water, are considered. This study found that the range of the control bandwidth should be optimized based on the ship's heading and wave parameters.
在斜尾波中航行会使船舶发生急转弯和无法控制的航向偏离，并伴有较大的后跟，有时会导致倾覆。研究斜尾波下的控制算法是十分必要的，因为一个好的控制方案可以提高船舶的航向保持稳定性。本文采用基于水动力导数的机动建模组(MMG)方法和基于计算流体力学(CFD)的自航仿真方法对船舶在波浪中的航行进行了仿真。本文研究了比例-积分-导数(PID)控制方案对基于流体动力导数和3d - of - MMG方法的航向维持稳定性的影响。然后，利用优化后的PID控制参数，利用CFD方法对船舶在斜波中进行了6DOF自推进航行仿真。在此过程中，考虑了舷侧急变、轰击、绿水等非线性现象。研究发现，控制带宽的范围应根据船舶航向和波浪参数进行优化。
{"title":"The effect of PID control scheme on the course-keeping of ship in oblique stern waves","authors":"Yunbo Li","doi":"10.21278/brod74408","DOIUrl":"https://doi.org/10.21278/brod74408","url":null,"abstract":"Sailing in oblique stern waves causes a ship to make sharp turns and uncontrollable course deviation, which is accompanied by a large heel and sometimes leads to capsizing. Studying the control algorithm in oblique stern waves is imperative because an excellent controller scheme can improve the ship’s course-keeping stability. This paper uses the Maneuvering Modelling Group (MMG) method based on hydrodynamic derivatives and the Computational Fluid Dynamics (CFD)-based self-navigation simulation to simulate ship navigation in waves. This study examines the effect of proportion-integral-derivative (PID) controller schemes on the stability of course maintenance based on hydrodynamic derivatives and 3DOF MMG methods. Then, the optimized PID control parameters are used to simulate the ship’s 6DOF self-propulsion navigation in oblique waves using the CFD method. The nonlinear phenomena during the process, such as side-hull emergency, slamming, and green water, are considered. This study found that the range of the control bandwidth should be optimized based on the ship's heading and wave parameters.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135735141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the crucial aspects of the conceptual design of a stepped planing hull is the prediction of its performance. To improve performance, the prediction of total resistance must become more accurate. In the field of research, both towing tank experiments and numerical analysis may be used to achieve this goal. In this study, experiments were conducted initially to investigate total resistance of a relatively high-speed craft without a transverse step. Later, numerical computations were carried out to validate the experimental results. After it was determined that the test results and CFD methods were in good agreement, the experimental method continued to investigate the resistance properties of the hull with four different configurations to evaluate the optimal longitudinal position of a single transverse step. The ideal longitudinal position of the single transverse step was evaluated based on a similar relatively high-speed hull with a velocity of up to beam Froude number (FrB) 2.56 in this study, focusing on the FrB range between 2.30 and 2.45.
{"title":"Investigation of the optimum longitudinal single transverse step location for a high-speed craft","authors":"A. Avci, B. Barlas","doi":"10.21278/brod74303","DOIUrl":"https://doi.org/10.21278/brod74303","url":null,"abstract":"One of the crucial aspects of the conceptual design of a stepped planing hull is the prediction of its performance. To improve performance, the prediction of total resistance must become more accurate. In the field of research, both towing tank experiments and numerical analysis may be used to achieve this goal. In this study, experiments were conducted initially to investigate total resistance of a relatively high-speed craft without a transverse step. Later, numerical computations were carried out to validate the experimental results. After it was determined that the test results and CFD methods were in good agreement, the experimental method continued to investigate the resistance properties of the hull with four different configurations to evaluate the optimal longitudinal position of a single transverse step. The ideal longitudinal position of the single transverse step was evaluated based on a similar relatively high-speed hull with a velocity of up to beam Froude number (FrB) 2.56 in this study, focusing on the FrB range between 2.30 and 2.45.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45614808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to the complex fluid interference between outrigger and main hull, it is difficult to predict the trimaran load fluctuation accurately in different marine environments. Therefore, a time-domain Rankine method is developed to improve the accuracy of trimaran load prediction. This method successfully adds the nonlinear load components in time-domain load simulation by taking into account the factors such as instantaneous hull wetted surface, steady ship waves, green wave and slamming. Additionally, the nonlinear growth of green wave and slamming is also observed at outrigger and wet deck, with the increasing of speeds and wave heights. Finally, the relatively smaller errors in the Rankine method are confirmed by comparison with the values from a trimaran model test and linear time-domain load prediction method. Furthermore, the weakly nonlinear Rankine method is considered to be more suitable for trimaran load prediction under harsh marine environment.
{"title":"Numerical study of trimaran wave load based on time-domain Rankine method","authors":"Haoyun Tang, Q. Wan, H. Ren","doi":"10.21278/brod74306","DOIUrl":"https://doi.org/10.21278/brod74306","url":null,"abstract":"Due to the complex fluid interference between outrigger and main hull, it is difficult to predict the trimaran load fluctuation accurately in different marine environments. Therefore, a time-domain Rankine method is developed to improve the accuracy of trimaran load prediction. This method successfully adds the nonlinear load components in time-domain load simulation by taking into account the factors such as instantaneous hull wetted surface, steady ship waves, green wave and slamming. Additionally, the nonlinear growth of green wave and slamming is also observed at outrigger and wet deck, with the increasing of speeds and wave heights. Finally, the relatively smaller errors in the Rankine method are confirmed by comparison with the values from a trimaran model test and linear time-domain load prediction method. Furthermore, the weakly nonlinear Rankine method is considered to be more suitable for trimaran load prediction under harsh marine environment.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46067073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a fast alternative optimization method for developing a reliable optimal controller that can handle system model parameter uncertainties. The source of uncertainty in this study is identified as hydrodynamic coefficients, which are prone to errors due to the challenges involved in obtaining accurate values. The proposed optimization method utilizes a complex nonlinear ship model provided by Maneuver Modelling Group (MMG) as the reference for the ship motion model. The optimization process is divided into two stages: a blind search followed by bisection optimization, to obtain a robust optimal controller. To demonstrate the effectiveness of the proposed approach, system response analysis and practical tests were performed on Step, M-Turn, and Doublet maneuvers. The results show that the controller parameters obtained from the proposed optimization method are capable of achieving high success rates in controlling a system with uncertain parameters.
{"title":"Robust optimal control of a nonlinear surface vessel model with parametric uncertainties","authors":"Ahmad Irham Jambak, I. Bayezit","doi":"10.21278/brod74307","DOIUrl":"https://doi.org/10.21278/brod74307","url":null,"abstract":"This paper presents a fast alternative optimization method for developing a reliable optimal controller that can handle system model parameter uncertainties. The source of uncertainty in this study is identified as hydrodynamic coefficients, which are prone to errors due to the challenges involved in obtaining accurate values. The proposed optimization method utilizes a complex nonlinear ship model provided by Maneuver Modelling Group (MMG) as the reference for the ship motion model. The optimization process is divided into two stages: a blind search followed by bisection optimization, to obtain a robust optimal controller. To demonstrate the effectiveness of the proposed approach, system response analysis and practical tests were performed on Step, M-Turn, and Doublet maneuvers. The results show that the controller parameters obtained from the proposed optimization method are capable of achieving high success rates in controlling a system with uncertain parameters.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44904752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To evaluate the time-domain positioning performance of arctic marine structures, it is necessary to generate an ice load appropriate for the current position and heading of the structure. The position and orientation angle of a floating body continuously change with time. Therefore, an ice load is required for any attitude in the time-domain simulation. In this study, we present a fundamental technique for analyzing ice loads in the frequency domain based on data measured at various angles in the ice-water tank experiment. We perform spectral analysis instead of general FFT to analyze the ice load, which has the characteristics of a random signal. To generate the necessary ice load in the time domain, we must first interpolate the measured data in the frequency domain. Using the Blackman-Tukey method, we estimate the spectrum for the measured data, then process the data to generate the training set required for machine learning. Based on the results, we perform regression analysis by applying four representative techniques, including linear regression, random forest, or neural network, and compare the results with MSE. The deep neural network method performed best, but we provide further discussion for each model.
{"title":"A comparison of regression models for the ice loads measured during the ice tank test","authors":"Seung Jae Lee, K. Jung, Namkug Ku, Jaeyong Lee","doi":"10.21278/brod74301","DOIUrl":"https://doi.org/10.21278/brod74301","url":null,"abstract":"To evaluate the time-domain positioning performance of arctic marine structures, it is necessary to generate an ice load appropriate for the current position and heading of the structure. The position and orientation angle of a floating body continuously change with time. Therefore, an ice load is required for any attitude in the time-domain simulation. In this study, we present a fundamental technique for analyzing ice loads in the frequency domain based on data measured at various angles in the ice-water tank experiment. We perform spectral analysis instead of general FFT to analyze the ice load, which has the characteristics of a random signal. To generate the necessary ice load in the time domain, we must first interpolate the measured data in the frequency domain. Using the Blackman-Tukey method, we estimate the spectrum for the measured data, then process the data to generate the training set required for machine learning. Based on the results, we perform regression analysis by applying four representative techniques, including linear regression, random forest, or neural network, and compare the results with MSE. The deep neural network method performed best, but we provide further discussion for each model.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43985219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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