In this paper, exact hydrostatic particulars equations for the centre of buoyancy curve and metacentric locus curve are given for rectangular cross section using quadratic functions. Those equations have not been given for the hyperbola range of the heel angles so far, and here it is done by using basic quadratic functions and their horizontally symmetric immersion shapes, with two new methods defined: 1. Rotation of basic cross section shapes, and 2. Hydrostatic cross section area complement method that uses homothety or scaling properties of emerged and immersed areas of the rectangular cross section. Observed metacentric curve for rectangle consists of semi-cubic parabolas and Lamé curve with 2/3 exponent and negative sign, resulting in the cusp discontinuities in the symmetry of those functions definition. In order to achieve above, two theorems are given: the theorem about scaling using hydrostatic cross section area complement and the theorem about parallelism of centre of buoyancy tangents with waterlines. After non-dimensional bounds are given for the existence of the swallowtail discontinuity of metacentric curve for rectangular cross section in the Part 1 of this paper, the proof of its position in the symmetry of rectangle vertex angle is given in this Part 2 of the paper, thus confirming its position from theory.
{"title":"Re-examination of centre of buoyancy curve and its evolute for rectangular cross section, Part 2: Using quadratic functions","authors":"D. Ban","doi":"10.21278/brod74302","DOIUrl":"https://doi.org/10.21278/brod74302","url":null,"abstract":"In this paper, exact hydrostatic particulars equations for the centre of buoyancy curve and metacentric locus curve are given for rectangular cross section using quadratic functions. Those equations have not been given for the hyperbola range of the heel angles so far, and here it is done by using basic quadratic functions and their horizontally symmetric immersion shapes, with two new methods defined: 1. Rotation of basic cross section shapes, and 2. Hydrostatic cross section area complement method that uses homothety or scaling properties of emerged and immersed areas of the rectangular cross section. Observed metacentric curve for rectangle consists of semi-cubic parabolas and Lamé curve with 2/3 exponent and negative sign, resulting in the cusp discontinuities in the symmetry of those functions definition. In order to achieve above, two theorems are given: the theorem about scaling using hydrostatic cross section area complement and the theorem about parallelism of centre of buoyancy tangents with waterlines. After non-dimensional bounds are given for the existence of the swallowtail discontinuity of metacentric curve for rectangular cross section in the Part 1 of this paper, the proof of its position in the symmetry of rectangle vertex angle is given in this Part 2 of the paper, thus confirming its position from theory.","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":"49313526","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 competitive advantage over other shipyards is extremely important in the high-stake shipbuilding industry. Typically, a competitiveness analysis of a shipyard measures productivity based on specific parameters, such as tonnes or compensated gross tons produced per consumed working hour. The authors of this paper consider identifying the technological level required to achieve this productivity as essential, including other information relevant for the shipbuilding process. Therefore, a methodology for determining the technological level of shipyards is proposed based on defined criteria and a structured evaluation. The criteria were devised and structured hierarchically. The methodology also offers company management a solution for continuous monitoring for improving shipyard design and production processes.
{"title":"The shipyard technological level evaluation methodology","authors":"Rajko Rubeša, M. Hadjina, T. Matulja, D. Bolf","doi":"10.21278/brod74305","DOIUrl":"https://doi.org/10.21278/brod74305","url":null,"abstract":"A competitive advantage over other shipyards is extremely important in the high-stake shipbuilding industry. Typically, a competitiveness analysis of a shipyard measures productivity based on specific parameters, such as tonnes or compensated gross tons produced per consumed working hour. The authors of this paper consider identifying the technological level required to achieve this productivity as essential, including other information relevant for the shipbuilding process. Therefore, a methodology for determining the technological level of shipyards is proposed based on defined criteria and a structured evaluation. The criteria were devised and structured hierarchically. The methodology also offers company management a solution for continuous monitoring for improving shipyard design and production processes.","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":"44359453","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}
Inland waterways vessels (IWV) have no mandatory regulations regarding their energy efficiency, as sea-going ships have. So far, there are just two proposed design energy efficiency evaluation methods, both based on IMO EEDI approach and data on EU inland navigation. Operational indicators and real-time navigation measurements from available literature do not exist. Therefore, this paper aims to introduce the energy efficiency in operation (EEO), assessed for the typical Danube cargo vessel. Firstly, an operational profile is acquired by tracking the vessel’s voyages, and by identifying actual constraints of each sector the vessel has sailed during the designated time. Secondly, EEO is incorporated within two available methods and calculated based on acquired operational data considering different navigational conditions. The paper shows how the energy efficiency vastly depends on variables such as water depth, current speed, draught, deadweight, river constraints. Analysis is performed for the most employed month of the vessel navigation, and annually. Depending on water level scenarios and during the selected month of sailing, the total amount of CO2 emitted is estimated to be between 22.7 t and 29.9 t, while the necessary average speed reduction (i.e., slow steaming) per sectoral voyage for the requirement compliance is calculated to be in between 4.8%-26%. Slow steaming is assessed to extend the time of voyage for 6.1-10.7 hours on monthly basis and 49-87 hours annually.
{"title":"Inland waterway cargo vessel energy efficiency in operation","authors":"M. Kalajdžić, Matija Vasilev, N. Momčilović","doi":"10.21278/brod74304","DOIUrl":"https://doi.org/10.21278/brod74304","url":null,"abstract":"Inland waterways vessels (IWV) have no mandatory regulations regarding their energy efficiency, as sea-going ships have. So far, there are just two proposed design energy efficiency evaluation methods, both based on IMO EEDI approach and data on EU inland navigation. Operational indicators and real-time navigation measurements from available literature do not exist. Therefore, this paper aims to introduce the energy efficiency in operation (EEO), assessed for the typical Danube cargo vessel. Firstly, an operational profile is acquired by tracking the vessel’s voyages, and by identifying actual constraints of each sector the vessel has sailed during the designated time. Secondly, EEO is incorporated within two available methods and calculated based on acquired operational data considering different navigational conditions. The paper shows how the energy efficiency vastly depends on variables such as water depth, current speed, draught, deadweight, river constraints. Analysis is performed for the most employed month of the vessel navigation, and annually. Depending on water level scenarios and during the selected month of sailing, the total amount of CO2 emitted is estimated to be between 22.7 t and 29.9 t, while the necessary average speed reduction (i.e., slow steaming) per sectoral voyage for the requirement compliance is calculated to be in between 4.8%-26%. Slow steaming is assessed to extend the time of voyage for 6.1-10.7 hours on monthly basis and 49-87 hours annually.","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":"48459652","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}
Liu Liang, Zhang Baoji, Zhang Hao, Hailin Tang, Weijie Wang
Fiber-reinforced composites offer the benefits of high strength, high stiffness, lightweight, superior damping performance, and great design capability when compared to metal. The rigidity characteristics of the composite laminate in different directions may be adjusted to meet the requirements of the application by using appropriate materials and arranging the lay-up sequence. As a result, the purpose of this work is to explore the influence of lay-up type on propeller performance in terms of both hydrodynamic and structural performance. A transient fluid-structure interaction (FSI) algorithm based on the finite element method (FEM) combined with the computational fluid dynamics (CFD) technique is developed and used for the analysis of composite propellers. The hydrodynamic performance of the propeller is compared to that of a metallic material. Propeller propulsion efficiency, structural deformation, equivalent stress, and damage performance of different lay-up options under three different operating situations are compared. In addition, it is presented a parametric optimization approach to get the most appropriate lay-up program for composite blades with the best hydrodynamic properties and structural performance.
{"title":"Hydrodynamic performance optimization of marine propellers based on fluid-structure coupling","authors":"Liu Liang, Zhang Baoji, Zhang Hao, Hailin Tang, Weijie Wang","doi":"10.21278/brod74308","DOIUrl":"https://doi.org/10.21278/brod74308","url":null,"abstract":"Fiber-reinforced composites offer the benefits of high strength, high stiffness, lightweight, superior damping performance, and great design capability when compared to metal. The rigidity characteristics of the composite laminate in different directions may be adjusted to meet the requirements of the application by using appropriate materials and arranging the lay-up sequence. As a result, the purpose of this work is to explore the influence of lay-up type on propeller performance in terms of both hydrodynamic and structural performance. A transient fluid-structure interaction (FSI) algorithm based on the finite element method (FEM) combined with the computational fluid dynamics (CFD) technique is developed and used for the analysis of composite propellers. The hydrodynamic performance of the propeller is compared to that of a metallic material. Propeller propulsion efficiency, structural deformation, equivalent stress, and damage performance of different lay-up options under three different operating situations are compared. In addition, it is presented a parametric optimization approach to get the most appropriate lay-up program for composite blades with the best hydrodynamic properties and structural performance.","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":"42722543","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}
Present paper studies the variation of the blade spindle torque in a controllable pitch propeller (CPP) during the feathering maneuver, which is one of the rare but most challenging propeller maneuvers in CPP operation. The knowledge of the spindle torque under different operating conditions is one of the key features for the CPP controller unit design. The aim of this study is determining the forces needed to be governed to control the blade motion of a CPP converted from a fixed pitch propeller and the scale effect on these forces. So as to obtain a realistic numerical setup, the time-dependent superposed motion of the main rotation of the propeller and the rotation of each blade around its axis is modeled using a hybrid overset/sliding mesh technique. The spindle torque values were calculated during the dynamical variation of the blade pitch in feathering maneuver, and a novel expression is recommended to non-dimensionalize the predicted spindle torque. The result revealed that the required torque values to rotate each blade during the propeller maneuver is rising up to a critical pitch angle. Further increment of the pitch angle results in lower spindle torque values. Furthermore, this critical pitch angle is inversely proportional to the propeller loading.
{"title":"The numerical investigation of spindle torque for a controllable pitch propeller in feathering maneuver","authors":"A. Yurtseven, Kaan Aktay","doi":"10.21278/brod74205","DOIUrl":"https://doi.org/10.21278/brod74205","url":null,"abstract":"Present paper studies the variation of the blade spindle torque in a controllable pitch propeller (CPP) during the feathering maneuver, which is one of the rare but most challenging propeller maneuvers in CPP operation. The knowledge of the spindle torque under different operating conditions is one of the key features for the CPP controller unit design. The aim of this study is determining the forces needed to be governed to control the blade motion of a CPP converted from a fixed pitch propeller and the scale effect on these forces. So as to obtain a realistic numerical setup, the time-dependent superposed motion of the main rotation of the propeller and the rotation of each blade around its axis is modeled using a hybrid overset/sliding mesh technique. The spindle torque values were calculated during the dynamical variation of the blade pitch in feathering maneuver, and a novel expression is recommended to non-dimensionalize the predicted spindle torque. The result revealed that the required torque values to rotate each blade during the propeller maneuver is rising up to a critical pitch angle. Further increment of the pitch angle results in lower spindle torque values. Furthermore, this critical pitch angle is inversely proportional to the propeller loading.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49633307","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}
At the beginning of the naval architecture theory, in the 18th century, Bouguer and Euler set the foundations of naval architecture with the centre of buoyancy and metacentric curve definition. After that, in 20th century, it is determined from bifurcation and catastrophe theory developed by Thom, and its application for ships in works of Zeeman, Stewart and others, that the centre of buoyancy curve for the rectangular cross section consists of parabola and hyperbola equations, but no exact equations are given for the hyperbola segment of that curve. Therefore, the hyperbola segment of the centre of the buoyancy curve is re-examined in this paper with emphasis on belonging metacentric locus curve as the evolute of the centre of the buoyancy curve. The observed metacentric curve consists of semi-cubic parabolas and Lamé curves with 2/3 exponent and negative sign, resulting in the cusp discontinuities in the symmetry of functions definition. Belonging swallowtail discontinuity in the hyperbola range between two heel angles of the rectangular cross section deck immersion/bottom emersion angles is examined, depending on existence of extremes of belonging hyperbola curve. After that, the single condition for hyperbola extreme the existence is given with the belonging new lower and upper non-dimensional bounds of rectangle cross section dimensions.
{"title":"Re-examination of centre of buoyancy curve and its evolute for rectangular cross section, part 1: swallowtail discontinuity bounds","authors":"D. Ban","doi":"10.21278/brod74201","DOIUrl":"https://doi.org/10.21278/brod74201","url":null,"abstract":"At the beginning of the naval architecture theory, in the 18th century, Bouguer and Euler set the foundations of naval architecture with the centre of buoyancy and metacentric curve definition. After that, in 20th century, it is determined from bifurcation and catastrophe theory developed by Thom, and its application for ships in works of Zeeman, Stewart and others, that the centre of buoyancy curve for the rectangular cross section consists of parabola and hyperbola equations, but no exact equations are given for the hyperbola segment of that curve. Therefore, the hyperbola segment of the centre of the buoyancy curve is re-examined in this paper with emphasis on belonging metacentric locus curve as the evolute of the centre of the buoyancy curve. The observed metacentric curve consists of semi-cubic parabolas and Lamé curves with 2/3 exponent and negative sign, resulting in the cusp discontinuities in the symmetry of functions definition. Belonging swallowtail discontinuity in the hyperbola range between two heel angles of the rectangular cross section deck immersion/bottom emersion angles is examined, depending on existence of extremes of belonging hyperbola curve. After that, the single condition for hyperbola extreme the existence is given with the belonging new lower and upper non-dimensional bounds of rectangle cross section dimensions.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":"1 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67955544","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}
Bin Wang, Yuqi Jiao, D. Qiao, Shan Gao, Tianfei Li, J. Ou
As a widely used taut-wire mooring system for deepwater platforms, the Vertically Loaded Anchor (VLA) has better performance in bearing capacity, angle adaptability, and deepwater installation than other systems. However, the installation process of the VLA and its motion characteristics are significantly impacted by multi-layered seabed soil. In this paper, the coupled Eulerian‒Lagrangian (CEL) large deformation finite element analysis method has been applied to analyse the continuous penetration of a VLA in nonuniform clay with an interbedded stiff layer. A detailed parametric study has been carried out to explore the trajectory, drag angle, movement direction and drag force of the VLA in layered clay with different embedded depths, thicknesses and undrained shear strength of the stiff layer. The CEL numerical analysis results have been validated by comparison with the analytical solutions from the inverse catenary equation. Excellent agreement has been obtained between the results from the CEL analyses and the analytical solutions. The stiff layer leads to concave and convex shapes on the trend lines of the movement direction angle and drag forces, respectively. The embedded depth of the stiff layer determines where the concave and convex shapes appear on the trend lines, while the thickness affects the sizes of the openings of the shapes. The most decisive parameter, an abrupt variation in the undrained shear strength, causes predominant rotation at the interface of layered clay. It diminishes the final embedment depth and ultimate stable drag force, meaning that the bearing capacity of the VLA severely declined in layered clay.
{"title":"Motion characteristics of vertically loaded anchor during drag embedment in layered clay","authors":"Bin Wang, Yuqi Jiao, D. Qiao, Shan Gao, Tianfei Li, J. Ou","doi":"10.21278/brod74206","DOIUrl":"https://doi.org/10.21278/brod74206","url":null,"abstract":"As a widely used taut-wire mooring system for deepwater platforms, the Vertically Loaded Anchor (VLA) has better performance in bearing capacity, angle adaptability, and deepwater installation than other systems. However, the installation process of the VLA and its motion characteristics are significantly impacted by multi-layered seabed soil. In this paper, the coupled Eulerian‒Lagrangian (CEL) large deformation finite element analysis method has been applied to analyse the continuous penetration of a VLA in nonuniform clay with an interbedded stiff layer. A detailed parametric study has been carried out to explore the trajectory, drag angle, movement direction and drag force of the VLA in layered clay with different embedded depths, thicknesses and undrained shear strength of the stiff layer. The CEL numerical analysis results have been validated by comparison with the analytical solutions from the inverse catenary equation. Excellent agreement has been obtained between the results from the CEL analyses and the analytical solutions. The stiff layer leads to concave and convex shapes on the trend lines of the movement direction angle and drag forces, respectively. The embedded depth of the stiff layer determines where the concave and convex shapes appear on the trend lines, while the thickness affects the sizes of the openings of the shapes. The most decisive parameter, an abrupt variation in the undrained shear strength, causes predominant rotation at the interface of layered clay. It diminishes the final embedment depth and ultimate stable drag force, meaning that the bearing capacity of the VLA severely declined in layered clay.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48201790","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}
Slow steaming is an effective operational measure that reduces fuel consumption and thus emissions on board. With the Carbon Intensity Indicator (CII) regulation coming into force in 2023 from the International Maritime Organization (IMO), ships will have to reduce their CO2 emissions even more. The practice of slow steaming is an important measure to comply with this regulation. In this study, real voyage data of a general cargo ship was used. The changes in fuel consumption, CO2, CH4, N2O, and BC emissions, 20-year global warming potential (GWP20), and 100-year global warming potential (GWP100) of the ship were analysed under different scenarios (75%, 38%, 27%, and 19% main engine load), and the voyage expenses and cost-benefit ratio were calculated. At 38% main engine load, 31.5% less emissions were released than at 75% main engine load. At 27% and 19% main engine load, the emission reduction was 40.6% and 50.1%, respectively. The CO2 reduction target of 40% by 2030 and 50% by 2050 compared to 2008 levels in the IMO Initial GHG Strategy was achieved with slow steaming. As CO2 emissions decreased due to the application of slow steaming, this had a positive impact on the ship's CII rating and it remained at the A rating without further action. Nevertheless, it remains at the A rating with slow steaming, the amount of emissions varies depending on the rate of application of slow steaming in three different scenarios, and this shows that the environmental impact of each A rating is not the same. The results of the economic analysis show that operating costs increase and fuel costs decrease when the travel time is extended with slow steaming. As a result, the total voyage expenses decreased by up to 23.3%.
{"title":"Slow steaming application for short-sea shipping to comply with the CII regulation","authors":"B. Zincir","doi":"10.21278/brod74202","DOIUrl":"https://doi.org/10.21278/brod74202","url":null,"abstract":"Slow steaming is an effective operational measure that reduces fuel consumption and thus emissions on board. With the Carbon Intensity Indicator (CII) regulation coming into force in 2023 from the International Maritime Organization (IMO), ships will have to reduce their CO2 emissions even more. The practice of slow steaming is an important measure to comply with this regulation. In this study, real voyage data of a general cargo ship was used. The changes in fuel consumption, CO2, CH4, N2O, and BC emissions, 20-year global warming potential (GWP20), and 100-year global warming potential (GWP100) of the ship were analysed under different scenarios (75%, 38%, 27%, and 19% main engine load), and the voyage expenses and cost-benefit ratio were calculated. At 38% main engine load, 31.5% less emissions were released than at 75% main engine load. At 27% and 19% main engine load, the emission reduction was 40.6% and 50.1%, respectively. The CO2 reduction target of 40% by 2030 and 50% by 2050 compared to 2008 levels in the IMO Initial GHG Strategy was achieved with slow steaming. As CO2 emissions decreased due to the application of slow steaming, this had a positive impact on the ship's CII rating and it remained at the A rating without further action. Nevertheless, it remains at the A rating with slow steaming, the amount of emissions varies depending on the rate of application of slow steaming in three different scenarios, and this shows that the environmental impact of each A rating is not the same. The results of the economic analysis show that operating costs increase and fuel costs decrease when the travel time is extended with slow steaming. As a result, the total voyage expenses decreased by up to 23.3%.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47590945","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}
The most significant aspect of international shipping is sea transportation, and the developments to be made in maritime transport will inspire and predict all other fields. Therefore, determining a ship’s main engine power has great importance in terms of both energy efficiency and environmental factors. The maritime transport and shipping industry has currently begun to understand the importance of artificial intelligence technology. This study uses an artificial neural network (ANN) model to predict the main engine power and pollutant emissions of container, cargo, and tanker ships over 14 parameters: maximum speed, average speed, breadth, year built, ship type, status, length overall (LOA), light displacement, summer displacement, fuel type, deadweight tonnage (DWT), gross tonnage, engine cylinder size, and engine stroke length. In order to provide accurate results, the ANN analysis was trained with data from 3,020 ships, which is quite high compared to the studies in the literature. Many ANN models have been developed and compared to achieve minimal errors and highest accuracy in the results. The regression values, which involve the training, validation, and test values for the different ship types, were obtained as 0.99773 for container ships, 0.98964 for cargo ships, and 0.97755 for tanker ships, with a value of 0.97189 for all ships. The ANN structure was tested using many variations for hidden neuron counts, with the ANN analysis made with 30 neurons obtaining the best results. The ANN analysis results were compared with real values, which showed that very accurate results had been obtained according to the mean squared error (MSE), regression, and mean absolute percentage error (MAPE) results. The MSE value had exceeded 20,000 in the two-input ANN model, but decreased to 0.03, 0.081, and 0.13 with the 14-input model for container, cargo, and tanker ships, respectively. In order to make accurate predictions with maximum precision in the ANN analyses, the study attempted to use different values for the numbers of hidden neurons and inputs and then presented the performance results. The developed model can be used in future studies to be done on fuel consumption and energy efficiency for ships in maritime transport.
{"title":"Predicting main engine power and emissions for container, cargo, and tanker ships with artificial neural network analysis","authors":"Ibrahim Ozsari","doi":"10.21278/brod74204","DOIUrl":"https://doi.org/10.21278/brod74204","url":null,"abstract":"The most significant aspect of international shipping is sea transportation, and the developments to be made in maritime transport will inspire and predict all other fields. Therefore, determining a ship’s main engine power has great importance in terms of both energy efficiency and environmental factors. The maritime transport and shipping industry has currently begun to understand the importance of artificial intelligence technology. This study uses an artificial neural network (ANN) model to predict the main engine power and pollutant emissions of container, cargo, and tanker ships over 14 parameters: maximum speed, average speed, breadth, year built, ship type, status, length overall (LOA), light displacement, summer displacement, fuel type, deadweight tonnage (DWT), gross tonnage, engine cylinder size, and engine stroke length. In order to provide accurate results, the ANN analysis was trained with data from 3,020 ships, which is quite high compared to the studies in the literature. Many ANN models have been developed and compared to achieve minimal errors and highest accuracy in the results. The regression values, which involve the training, validation, and test values for the different ship types, were obtained as 0.99773 for container ships, 0.98964 for cargo ships, and 0.97755 for tanker ships, with a value of 0.97189 for all ships. The ANN structure was tested using many variations for hidden neuron counts, with the ANN analysis made with 30 neurons obtaining the best results. The ANN analysis results were compared with real values, which showed that very accurate results had been obtained according to the mean squared error (MSE), regression, and mean absolute percentage error (MAPE) results. The MSE value had exceeded 20,000 in the two-input ANN model, but decreased to 0.03, 0.081, and 0.13 with the 14-input model for container, cargo, and tanker ships, respectively. In order to make accurate predictions with maximum precision in the ANN analyses, the study attempted to use different values for the numbers of hidden neurons and inputs and then presented the performance results. The developed model can be used in future studies to be done on fuel consumption and energy efficiency for ships in maritime transport.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43436037","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}
Bin Wang, Yuqi Jiao, D. Qiao, Shan Gao, Tianfei Li, J. Ou
The soil reaction of the monopile foundation subjected to lateral loading in offshore wind turbines is typically assessed relying on p-y curves advocated by API. However, this method is inadequate for gradually increasing monopile diameters and significantly underestimates the lateral soil confinement. In the present works, a 3D pile-soil interaction finite element model was first established, considering the soil suction and strain hardening characteristics for the normally consolidated clay in China’s sea. Modifications to the p-y curves in API were accomplished in the comparative process between the lateral soil resistance-displacement curves retrieved from the finite element model and the representative expression. Furthermore, the prediction accuracy for the corrected p-y curves has been proved by forecasting the monopile lateral bearing capacity with varying length-to-diameter ratios, which also demonstrates that the modified p-y curves could successfully reflect the lateral soil confinement of the normally consolidated clay and flexible piles. It also provides an approach to assess the deformation response and horizontal ultimate bearing capacity of monopiles with different length-to-diameter ratios.
{"title":"Modified p-y curves for monopile foundation with different length-to-diameter ratio","authors":"Bin Wang, Yuqi Jiao, D. Qiao, Shan Gao, Tianfei Li, J. Ou","doi":"10.21278/brod74208","DOIUrl":"https://doi.org/10.21278/brod74208","url":null,"abstract":"The soil reaction of the monopile foundation subjected to lateral loading in offshore wind turbines is typically assessed relying on p-y curves advocated by API. However, this method is inadequate for gradually increasing monopile diameters and significantly underestimates the lateral soil confinement. In the present works, a 3D pile-soil interaction finite element model was first established, considering the soil suction and strain hardening characteristics for the normally consolidated clay in China’s sea. Modifications to the p-y curves in API were accomplished in the comparative process between the lateral soil resistance-displacement curves retrieved from the finite element model and the representative expression. Furthermore, the prediction accuracy for the corrected p-y curves has been proved by forecasting the monopile lateral bearing capacity with varying length-to-diameter ratios, which also demonstrates that the modified p-y curves could successfully reflect the lateral soil confinement of the normally consolidated clay and flexible piles. It also provides an approach to assess the deformation response and horizontal ultimate bearing capacity of monopiles with different length-to-diameter ratios.","PeriodicalId":55594,"journal":{"name":"Brodogradnja","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42906492","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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