Pub Date : 2024-05-29DOI: 10.1177/14750902241253319
Majid Rahimie Esfidan, Ahmad Rahbar Ranji
To have a proper maintenance policy for ships and offshore structures, it is necessary to predict corrosion wastage accurately. It is the main aim of the present work to propose corrosion models for plates in ship structures. In total 66,480 data were collected from thickness measurements carried out by different classification societies. The data were sorted out based on the position of the plate, the age of the ship, the country where the ship was built, and the type of ship. Using regression analysis, some models were proposed as a function of the ship’s age and position of plate. Based on this study, the proposed models are checked against existing corrosion models in the literature and it is found that other corrosion models underestimate the corrosion rate in the inner bottom plates, and deck plates. However, they overestimate the amount of corrosion in the side plates of ships. The existing corrosion models are justified for the prediction of corrosion wastage in hatch-coaming plates. For corrosion of outer bottom plates, the existing corrosion models are applicable for ships under 20 years old. They overestimate corrosion wastage for ships older than 20 years. Also, existing corrosion models overestimate corrosion wastage of plates at the side structure of ships above the water line at the early age of ships and underestimate in older ships.
{"title":"Corrosion models for steel plates in ship structure based on statistical data","authors":"Majid Rahimie Esfidan, Ahmad Rahbar Ranji","doi":"10.1177/14750902241253319","DOIUrl":"https://doi.org/10.1177/14750902241253319","url":null,"abstract":"To have a proper maintenance policy for ships and offshore structures, it is necessary to predict corrosion wastage accurately. It is the main aim of the present work to propose corrosion models for plates in ship structures. In total 66,480 data were collected from thickness measurements carried out by different classification societies. The data were sorted out based on the position of the plate, the age of the ship, the country where the ship was built, and the type of ship. Using regression analysis, some models were proposed as a function of the ship’s age and position of plate. Based on this study, the proposed models are checked against existing corrosion models in the literature and it is found that other corrosion models underestimate the corrosion rate in the inner bottom plates, and deck plates. However, they overestimate the amount of corrosion in the side plates of ships. The existing corrosion models are justified for the prediction of corrosion wastage in hatch-coaming plates. For corrosion of outer bottom plates, the existing corrosion models are applicable for ships under 20 years old. They overestimate corrosion wastage for ships older than 20 years. Also, existing corrosion models overestimate corrosion wastage of plates at the side structure of ships above the water line at the early age of ships and underestimate in older ships.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141192174","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}
Pub Date : 2024-04-22DOI: 10.1177/14750902241244417
M. Zarezadeh, N. M. Nouri, R. Madoliat
Automated optimization is increasingly used in engineering applications. In this study, RANS-based CFD, the NSGA II algorithm, and Kriging were used to optimize a section of a marine surface piercing Propeller (SPP) set. The hydrodynamic performance of the SPP is also determined using the CFD tool. The optimization process involves the NSGA II algorithm in combination with the Kriging method. The optimized geometry is simulated using the CFD tool. Then, the obtained results are added to the initial population and the optimization is repeated in the next iteration. Thus, fewer simulations were required because the addition of the data with the surrogate method was accompanied by a good distribution, using surface methods for the replacement of the main part in the required calculations. As shown, the trailing edge optimization can improve Kt in J = 1 by almost 10.5%, and Kq changes by almost 12%, so this method can be used as an optimization package for similar problems.
{"title":"Improving hydrodynamic performance of surface piercing propeller through trailing-edge optimization","authors":"M. Zarezadeh, N. M. Nouri, R. Madoliat","doi":"10.1177/14750902241244417","DOIUrl":"https://doi.org/10.1177/14750902241244417","url":null,"abstract":"Automated optimization is increasingly used in engineering applications. In this study, RANS-based CFD, the NSGA II algorithm, and Kriging were used to optimize a section of a marine surface piercing Propeller (SPP) set. The hydrodynamic performance of the SPP is also determined using the CFD tool. The optimization process involves the NSGA II algorithm in combination with the Kriging method. The optimized geometry is simulated using the CFD tool. Then, the obtained results are added to the initial population and the optimization is repeated in the next iteration. Thus, fewer simulations were required because the addition of the data with the surrogate method was accompanied by a good distribution, using surface methods for the replacement of the main part in the required calculations. As shown, the trailing edge optimization can improve Kt in J = 1 by almost 10.5%, and Kq changes by almost 12%, so this method can be used as an optimization package for similar problems.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140676766","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}
Pub Date : 2024-04-16DOI: 10.1177/14750902241245539
Zhiqiang Han, Yang Liu, Xiaohong Wu, Daekyun Oh, Jaewon Jang
The design and construction characteristics, including glass fibre weight fraction ( Gc), number of single-ply layers, fabric combination, and fabrication quality, of glass fibre reinforcement polymer (GFRP) hull plates affect ultrasound propagation characteristics, such as ultrasonic velocity and attenuation, thereby influencing the accuracy of ultrasonic non-destructive test results. Therefore, this study is to propose a method to decrease the ultrasonic test errors of GFRP hull plate by using statistical method. The GFRP specimens with Gc of approximately 30–50 wt%, thicknesses of approximately 5–20 mm, and different fabric combinations were prepared using the hand lay-up method, considering the general design–construction characteristics. Further, an ultrasonic velocity decision method for ultrasonic inspection was proposed considering the GFRP hull design-construction characteristics, such as Gc and number of single-ply layers of hull plate by multiple linear regression method. The results show that the proposed method can reduce the thickness measurement error from approximately 20%–30% to 1%–2%, compared to an existing ultrasonic inspection method, only considering the Gc effect on ultrasonic velocity, which indicates that the proposed test method is suitable for practical applications.
{"title":"Ultrasonic non-destructive inspection method for glass fibre reinforcement polymer (GFRP) hull plates considering design and construction characteristics","authors":"Zhiqiang Han, Yang Liu, Xiaohong Wu, Daekyun Oh, Jaewon Jang","doi":"10.1177/14750902241245539","DOIUrl":"https://doi.org/10.1177/14750902241245539","url":null,"abstract":"The design and construction characteristics, including glass fibre weight fraction ( Gc), number of single-ply layers, fabric combination, and fabrication quality, of glass fibre reinforcement polymer (GFRP) hull plates affect ultrasound propagation characteristics, such as ultrasonic velocity and attenuation, thereby influencing the accuracy of ultrasonic non-destructive test results. Therefore, this study is to propose a method to decrease the ultrasonic test errors of GFRP hull plate by using statistical method. The GFRP specimens with Gc of approximately 30–50 wt%, thicknesses of approximately 5–20 mm, and different fabric combinations were prepared using the hand lay-up method, considering the general design–construction characteristics. Further, an ultrasonic velocity decision method for ultrasonic inspection was proposed considering the GFRP hull design-construction characteristics, such as Gc and number of single-ply layers of hull plate by multiple linear regression method. The results show that the proposed method can reduce the thickness measurement error from approximately 20%–30% to 1%–2%, compared to an existing ultrasonic inspection method, only considering the Gc effect on ultrasonic velocity, which indicates that the proposed test method is suitable for practical applications.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140615898","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}
Pub Date : 2024-04-09DOI: 10.1177/14750902241242248
Wen Jiang, jin Zhao, Tao Bian, Wuxin Yu
This paper studies the effect of the duct geometry on the hydrodynamic performance of rim-driven thruster (RDT) based on Computational Fluid Dynamics (CFD) method. The effect of the thickness of the duct, the radius of the leading edge of the duct and the geometry of the trailing edge of the duct on the thrust coefficient, torque coefficient and efficiency are investigated and analyzed. The conclusion shows the thrust coefficient increases with the thickness of the duct decreasing, however the torque coefficient increases with the increase of the thickness of the duct, so the efficiency increasing with the decrease of the thickness of the duct. On the other hand, the radius of the leading edge of the duct has no significant effect on the thrust coefficient of the RDT. However, the torque coefficient of RDT decreases with the increase of the radius of the leading edge of the duct, so the efficiency of RDT increases with the increase of the radius of the leading edge of the duct. A comprehensive comparison shows that the RDT 15-0.5 (the duct thickness is 15 mm, the ratio of the radius of the leading edge of the duct and the duct thickness is 0.5) has the best hydrodynamic performance among the investigated RDT models in this work.
{"title":"Numerical analysis of the effect of the duct geometry on the hydrodynamic performance of rim-driven thruster","authors":"Wen Jiang, jin Zhao, Tao Bian, Wuxin Yu","doi":"10.1177/14750902241242248","DOIUrl":"https://doi.org/10.1177/14750902241242248","url":null,"abstract":"This paper studies the effect of the duct geometry on the hydrodynamic performance of rim-driven thruster (RDT) based on Computational Fluid Dynamics (CFD) method. The effect of the thickness of the duct, the radius of the leading edge of the duct and the geometry of the trailing edge of the duct on the thrust coefficient, torque coefficient and efficiency are investigated and analyzed. The conclusion shows the thrust coefficient increases with the thickness of the duct decreasing, however the torque coefficient increases with the increase of the thickness of the duct, so the efficiency increasing with the decrease of the thickness of the duct. On the other hand, the radius of the leading edge of the duct has no significant effect on the thrust coefficient of the RDT. However, the torque coefficient of RDT decreases with the increase of the radius of the leading edge of the duct, so the efficiency of RDT increases with the increase of the radius of the leading edge of the duct. A comprehensive comparison shows that the RDT 15-0.5 (the duct thickness is 15 mm, the ratio of the radius of the leading edge of the duct and the duct thickness is 0.5) has the best hydrodynamic performance among the investigated RDT models in this work.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140568452","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}
Pub Date : 2024-04-02DOI: 10.1177/14750902241240210
Chen Huang, Jijun Gu, Jichuan Jia, Leilei Chen, Shujiang Wang
DSR (Deep steep riser) is a new riser structure that reduces the ultra-high-tension load caused by the riser self-weight. In this paper, the mechanical behavior of DSR under different buoyancy module configurations and different ocean currents is studied. The finite element model of DSR is established based on co-rotational coordinate method. The model is solved by arc length method. The accuracy of the numerical method is verified by Abaqus software. Then, the effects of buoyancy module length and buoyancy factor on DSR are analyzed. Finally, the influence of different current incidence angles and velocities on DSR is evaluated. The results show that the DSR model based on the co-rotational coordinate method can effectively simulate the nonlinear behavior of large deformation of DSR. The method is simple, flexible and computationally efficient. This method can quickly improve the efficiency of numerical calculation in static analysis of deepwater riser. And DSR is feasible under certain conditions.
{"title":"Feasibility analysis of deep steep riser based on co-rotational coordinate method","authors":"Chen Huang, Jijun Gu, Jichuan Jia, Leilei Chen, Shujiang Wang","doi":"10.1177/14750902241240210","DOIUrl":"https://doi.org/10.1177/14750902241240210","url":null,"abstract":"DSR (Deep steep riser) is a new riser structure that reduces the ultra-high-tension load caused by the riser self-weight. In this paper, the mechanical behavior of DSR under different buoyancy module configurations and different ocean currents is studied. The finite element model of DSR is established based on co-rotational coordinate method. The model is solved by arc length method. The accuracy of the numerical method is verified by Abaqus software. Then, the effects of buoyancy module length and buoyancy factor on DSR are analyzed. Finally, the influence of different current incidence angles and velocities on DSR is evaluated. The results show that the DSR model based on the co-rotational coordinate method can effectively simulate the nonlinear behavior of large deformation of DSR. The method is simple, flexible and computationally efficient. This method can quickly improve the efficiency of numerical calculation in static analysis of deepwater riser. And DSR is feasible under certain conditions.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140568160","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}
Pub Date : 2024-03-28DOI: 10.1177/14750902241239361
Jiarui Huang, Lei Song, Zhuoyi Yang, Qilong Wu, Xiaochen Jiang, Cheng Wang
The motion response of offshore floating wind turbines significantly influences their structural integrity, power generation efficiency, operational complexity, safety, and stability. Therefore, predicting the motion response of offshore floating wind turbines is of paramount importance. In engineering practice, especially in extreme marine environments, the motion of wind turbines becomes more complex, making accurate prediction more challenging. In this era of rapid development in deep learning technology, some solutions have emerged for this problem. In this paper, we propose a hybrid model, namely the OVMD-FE-PSO-LSTM model. We begin by conducting numerical simulations of a 5 MW-OC4 semi-submersible floating wind turbine in extreme sea conditions, obtaining motion data for the turbine’s six degrees of freedom. We then decompose the initial motion data using an optimized traditional VMD method, assess the modal complexity with the FE method, combine modal components with similar complexity to reduce computational load, and make predictions using the PSO-LSTM model. Finally, we analyze and compare the predictive results of different models. The results demonstrate that the proposed hybrid model outperforms other comparative models in terms of accuracy, providing new insights into the prediction of the motion response of offshore floating wind turbines.
{"title":"Prediction of 6-DOF motion response of semi-submersible floating wind turbine in extreme sea conditions using OVMD-FE-PSO-LSTM methodology","authors":"Jiarui Huang, Lei Song, Zhuoyi Yang, Qilong Wu, Xiaochen Jiang, Cheng Wang","doi":"10.1177/14750902241239361","DOIUrl":"https://doi.org/10.1177/14750902241239361","url":null,"abstract":"The motion response of offshore floating wind turbines significantly influences their structural integrity, power generation efficiency, operational complexity, safety, and stability. Therefore, predicting the motion response of offshore floating wind turbines is of paramount importance. In engineering practice, especially in extreme marine environments, the motion of wind turbines becomes more complex, making accurate prediction more challenging. In this era of rapid development in deep learning technology, some solutions have emerged for this problem. In this paper, we propose a hybrid model, namely the OVMD-FE-PSO-LSTM model. We begin by conducting numerical simulations of a 5 MW-OC4 semi-submersible floating wind turbine in extreme sea conditions, obtaining motion data for the turbine’s six degrees of freedom. We then decompose the initial motion data using an optimized traditional VMD method, assess the modal complexity with the FE method, combine modal components with similar complexity to reduce computational load, and make predictions using the PSO-LSTM model. Finally, we analyze and compare the predictive results of different models. The results demonstrate that the proposed hybrid model outperforms other comparative models in terms of accuracy, providing new insights into the prediction of the motion response of offshore floating wind turbines.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140322515","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}
Pub Date : 2024-02-28DOI: 10.1177/14750902241231349
Xinxin Wei, Tianhong Yan, Tao Sun, Shulin Liu, Hongyi Du
The phenomenon of oblique water inflow is widespread in the operation of thrusters, which will cause adverse effects on the hydrodynamic performance of thrusters. In order to investigate the hydrodynamic performance and stress variation of the propeller in oblique flow, based on computational fluid dynamics theory, this paper takes the DTMB4119 propeller as the research object and conducts numerical simulation research on the propeller in oblique flow by solving the RANS equation. By calculating the open water performance curve and surface pressure distribution of the propeller, the rationality of the numerical method and the meshing are verified. Considering the flow field information such as velocity, oblique flow angles, flow line distribution, and pressure distribution, the changes in hydrodynamic characteristics of the propeller are simulated and analyzed. The results show that the uneven distribution of pressure on the propeller blade surface increases with a decrease in the advance coefficient. The force pulsation amplitude of a single blade increases with an increase in oblique flow angles. With the increase in oblique flow angles, the thrust, torque, and efficiency of the propeller show different increasing trends. With the increase in propeller advance coefficient, propeller thrust and torque decrease gradually, and propeller efficiency increases gradually. By using mature propellers, this paper has more reference value for studying the flow field around the ship hull and the hydrodynamic performance of propellers in the process of ship maneuvering.
{"title":"Research on the hydrodynamic performance of propellers under oblique flow conditions","authors":"Xinxin Wei, Tianhong Yan, Tao Sun, Shulin Liu, Hongyi Du","doi":"10.1177/14750902241231349","DOIUrl":"https://doi.org/10.1177/14750902241231349","url":null,"abstract":"The phenomenon of oblique water inflow is widespread in the operation of thrusters, which will cause adverse effects on the hydrodynamic performance of thrusters. In order to investigate the hydrodynamic performance and stress variation of the propeller in oblique flow, based on computational fluid dynamics theory, this paper takes the DTMB4119 propeller as the research object and conducts numerical simulation research on the propeller in oblique flow by solving the RANS equation. By calculating the open water performance curve and surface pressure distribution of the propeller, the rationality of the numerical method and the meshing are verified. Considering the flow field information such as velocity, oblique flow angles, flow line distribution, and pressure distribution, the changes in hydrodynamic characteristics of the propeller are simulated and analyzed. The results show that the uneven distribution of pressure on the propeller blade surface increases with a decrease in the advance coefficient. The force pulsation amplitude of a single blade increases with an increase in oblique flow angles. With the increase in oblique flow angles, the thrust, torque, and efficiency of the propeller show different increasing trends. With the increase in propeller advance coefficient, propeller thrust and torque decrease gradually, and propeller efficiency increases gradually. By using mature propellers, this paper has more reference value for studying the flow field around the ship hull and the hydrodynamic performance of propellers in the process of ship maneuvering.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140007289","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}
Pub Date : 2024-02-24DOI: 10.1177/14750902241232445
Dechun Zhang, Peng Li, Haoran Chen, Hong Yin, Yiren Yang
To overcome the difficulties of time-consuming and inefficient in the response calculations of the submerged cylindrical shell with internal substructures, this paper firstly presents a refined mode superposition method. In view of the necessity and difficulties of directly and quickly obtaining the frequencies and modes of structures submerged in fluid (named the wet modes), the wet modes are expanded by the modes in vacuum (dry modes) and solved by the energy method. The added kinetic energy of the fluid is calculated via boundary integration, and the Lagrange equations of the second kind is applied to the fluid-structure coupling equations. Then the wet modes are solved by eigenvalue calculation and the modal mass and stiffness of each order wet mode are obtained. Finally, they are used for establishing a mode superposition approach for response calculations. The accuracy of the present method is verified by ANSYS software. In this method, all the required data are obtained from the structural analysis and the traditional complicated fluid force modeling is no longer required. Thus it has the advantages of high computational efficiency and applicability. Compared to the traditional semi-analytic model, this modeling methodology has broad application potential for vibration problems of complex underwater structures since the structural dry modes can be solved efficiently by commercial software. It also has practical value as a theoretical reference for developing mode-superposition-based calculations for fluid-structure problems using commercial software.
{"title":"A refined mode superposition method for dynamical responses of an underwater cylindrical shell with substructures","authors":"Dechun Zhang, Peng Li, Haoran Chen, Hong Yin, Yiren Yang","doi":"10.1177/14750902241232445","DOIUrl":"https://doi.org/10.1177/14750902241232445","url":null,"abstract":"To overcome the difficulties of time-consuming and inefficient in the response calculations of the submerged cylindrical shell with internal substructures, this paper firstly presents a refined mode superposition method. In view of the necessity and difficulties of directly and quickly obtaining the frequencies and modes of structures submerged in fluid (named the wet modes), the wet modes are expanded by the modes in vacuum (dry modes) and solved by the energy method. The added kinetic energy of the fluid is calculated via boundary integration, and the Lagrange equations of the second kind is applied to the fluid-structure coupling equations. Then the wet modes are solved by eigenvalue calculation and the modal mass and stiffness of each order wet mode are obtained. Finally, they are used for establishing a mode superposition approach for response calculations. The accuracy of the present method is verified by ANSYS software. In this method, all the required data are obtained from the structural analysis and the traditional complicated fluid force modeling is no longer required. Thus it has the advantages of high computational efficiency and applicability. Compared to the traditional semi-analytic model, this modeling methodology has broad application potential for vibration problems of complex underwater structures since the structural dry modes can be solved efficiently by commercial software. It also has practical value as a theoretical reference for developing mode-superposition-based calculations for fluid-structure problems using commercial software.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139952081","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}
Pub Date : 2024-02-22DOI: 10.1177/14750902241230354
Siljung Yeo, Jeong Kuk Kim, Jae-Hyuk Choi, Won-Ju Lee
The shipping sector is one of the major contributors to greenhouse gas (GHG) emissions. We aimed to calculate GHG emissions categorized by ship type for all vessels registered in South Korea. Hence, for the first time in South Korea, a bottom-up method based on ship activity data was employed, estimating energy consumption and emissions by ship type. Data from ships registered from 2019 to 2021 were collected and reclassified by ship type, and operational profiles were developed. Based on these profiles, the emissions of major GHGs, including CO2, CH4, and N2O, were estimated for the 3-year period. Cargo ships accounted for the highest percentage of annual fuel consumption, approximately 62.7%–64.7% of the total fuel consumption for all ships. The GHG emissions were calculated to be an average of 4.644 million tonCO2e, which is approximately 6.5 times higher than those from oil tankers (0.710 million tonCO2e), the second-highest emitter. This highlights the need for intensified GHG reduction measures specifically targeting cargo ships, providing clear evidence for prompt and enhanced implementation. The research findings are expected to be utilized as substantiated data for developing specific and systematic GHG reduction policies tailored to each ship type.
{"title":"Estimation of greenhouse gas emissions from ships registered in South Korea based on activity data using the bottom-up approach","authors":"Siljung Yeo, Jeong Kuk Kim, Jae-Hyuk Choi, Won-Ju Lee","doi":"10.1177/14750902241230354","DOIUrl":"https://doi.org/10.1177/14750902241230354","url":null,"abstract":"The shipping sector is one of the major contributors to greenhouse gas (GHG) emissions. We aimed to calculate GHG emissions categorized by ship type for all vessels registered in South Korea. Hence, for the first time in South Korea, a bottom-up method based on ship activity data was employed, estimating energy consumption and emissions by ship type. Data from ships registered from 2019 to 2021 were collected and reclassified by ship type, and operational profiles were developed. Based on these profiles, the emissions of major GHGs, including CO<jats:sub>2</jats:sub>, CH<jats:sub>4</jats:sub>, and N<jats:sub>2</jats:sub>O, were estimated for the 3-year period. Cargo ships accounted for the highest percentage of annual fuel consumption, approximately 62.7%–64.7% of the total fuel consumption for all ships. The GHG emissions were calculated to be an average of 4.644 million tonCO<jats:sub>2</jats:sub>e, which is approximately 6.5 times higher than those from oil tankers (0.710 million tonCO<jats:sub>2</jats:sub>e), the second-highest emitter. This highlights the need for intensified GHG reduction measures specifically targeting cargo ships, providing clear evidence for prompt and enhanced implementation. The research findings are expected to be utilized as substantiated data for developing specific and systematic GHG reduction policies tailored to each ship type.","PeriodicalId":20667,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139952080","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}
Pub Date : 2024-02-22DOI: 10.1177/14750902241230351
Yujun Liu, Jing Liu, Guang Pan, Qiaogao Huang
Periodic isolation system is effectively applied in broadband vibration control. To further enhance the broadband vibration attenuation effect, the paper proposes a two-stage periodic isolation system for an underwater glider. The analytical model of the one-dimensional two-stage periodic isolation system is developed through the multi-degree of freedom spring mass model method. For illustrating the superiority of the proposed two-stage periodic isolator, the force transmission ratio and the wave propagation constant of the SDOF isolator, the single-stage periodic isolator, and the two-stage periodic isolator are calculated and compared. In order to obtain the dynamic parameter influences on the vibration isolation performances as the design guidelines of the two-stage periodic isolator, the parametrical study is carried out based on the analytical model. Furthermore, a two-stage periodic isolator is designed for an underwater glider. The application effect of the two-stage periodic isolator is investigated through analytical modeling and finite element method, comparing to the single-stage periodic isolator. The research results from the analytical models show the proposed two-stage periodic isolator could strength the broadband vibration suppression. The parametrical study results demonstrate the vibration attenuation bandgap and attenuation amount are greatly influenced by the designed dynamic parameters, such as the mass unit and the spring unit of the periodic isolator, the intermediate mass of the two-stage isolator, and the number of the periodic cells. In application study of an underwater glider, the finite element results verify that the two-stage periodic isolator has more vibration attenuation effect than the single-stage periodic isolator. The vibration isolation assessment according to the proposed analytical model gives good predictive performance before the finite element model verification.
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