This paper deals with modeling corrosion wastage over the fuel tanks＇ structures at the exemplar of ten aged bulk carriers. In this paper, employed method might be treated as a long term one, and it is based on Weibu...This paper deals with modeling corrosion wastage over the fuel tanks＇ structures at the exemplar of ten aged bulk carriers. In this paper, employed method might be treated as a long term one, and it is based on Weibull distribution parameters analysis. The purpose of these analyses is optimal assessing of the average corrosion losses for the bulk carriers＇ fuel tanks areas at different points of time during the whole period of the exploitation, due to uprising the structural stability and safety of bulk carriers in operation. Though, the applied approach, among others, might be of particular importance in determining the amounts （percentage/depths） of time-dependent corrosion losses over different areas of aging bulk carriers＇ fuel tanks during the operational circles, with the ultimate goal of keeping stability and safety of these vital vessels＇ structural components.展开更多
In this paper, well-known and structured Monte Carlo simulation technique has been employed in predicting the amounts of the corrosion wastage over some bulk carriers＇ structural elements in different points of time ...In this paper, well-known and structured Monte Carlo simulation technique has been employed in predicting the amounts of the corrosion wastage over some bulk carriers＇ structural elements in different points of time during their exploitation life. As a base for the realization of the simulations, the appropriate statistical data collected over the group of ten bulk carriers have been used. Both longitudinal and transversal ships＇ hull structural elements have been taken into the consideration. Due to some experts＇ knowledge in this domain, the critical hull zones are identified and certain interventions are done in the pre-processing of the input data to the Monte Carlo simulations, all with the aim of achieving better convergence between simulation results and the experts＇ expectations in this field.展开更多
The world is facing great challenges regarding the energy crisis and environmental pollution.One of the main challenges is the increasing number of ships with a lot of different types and sizes.In this research,it is ...The world is facing great challenges regarding the energy crisis and environmental pollution.One of the main challenges is the increasing number of ships with a lot of different types and sizes.In this research,it is essential to analyze the operational energy efficiency of sea-going ships since the previous studies have concentrated on the inland river ships.This working is carried out by analyzing of the energy efficiency operation for large size ships such as bulk carriers,container ships,etc.based on the resistance characteristics of different navigation environment factors.A numerical model of main engine energy efficiency operation was considered using the energy efficiency measure of IMO(International Maritime Organization),in particular using the Energy Efficiency Operational Indicator(EEOI)as a monitoring tool in this research.This EEOI numerical model was established and simulated through Simulink/Matlab and verified by the collected data from a certain vessel in Vietnam.The EEOI model was simulated under the different navigation environment conditions including various engine speed,wind speed,wave height,and water speed.After that,the simulation results of this research will be compared with experimental database of a certain bulk carrier namely M/V NSU JUSTICE 250,000 DWT.The results indicated that it is important to consider the main engine speed appropriately in ship operation in order to save energy onboard and reduce the greenhouse gas emission problem.展开更多
The ship energy efficiency management is an important topic in the field of the energy management onboard and the exhaust gases emission nowadays.The advanced model plays a vital role to improve the ship energy effici...The ship energy efficiency management is an important topic in the field of the energy management onboard and the exhaust gases emission nowadays.The advanced model plays a vital role to improve the ship energy efficiency management when considering the variable factors.The establishment of the ship energy efficiency model through energy efficiency operational indicator(EEOI)index has been conducted through Monte Carlo simulation method along with using the operation data of a bulk carrier.A bulk carrier is chosen,namely,M/V NSU JUSTICE 250,000 DWT of VINIC Shipping Transportation Company in Vietnam.This research uses the real operational data to perform a statistical methodology which calculates the various factors used to calculate EEOI.This method is supported by Matlab program through the curve fitting tool.The normal distribution estimation and the kernel density estimation method are used for the parametric curve fitting and non-parametric curve fitting,respectively.The average weather condition(wind speed and wave height)and the fouling condition of hull have been investigated and compared with the research results.The validation of the proposed methods has been conducted through the study of the external factors influencing the research results.The research result shows the optimal operational data for the fuel consumption at each certain voyage.This paper is useful for the ship-owners and the ship-operators in the field of the ship energy efficiency management.展开更多
Evolutionary algorithm is applied as an optimization method in this paper. The increment of cumulative failure probability of fatigue, inspection cost, inspection interval and means are adopted as limiting condition, ...Evolutionary algorithm is applied as an optimization method in this paper. The increment of cumulative failure probability of fatigue, inspection cost, inspection interval and means are adopted as limiting condition, objective function and optimization variable respectively. According to fatigue characteristics of ship structure, the optimization research of inspecting fatigue deteriorating is carried out. The optimal inspection planning of minimal inspection cost is chosen. An example of computation and comparison of inspection plans is given. The results demonstrate that an optimal inspection plan considering security and economics can be chosen by the means in this paper.展开更多
The ultimate bending moment and maximal shear stress of a bulk carrier with two structural forms （single hull and double hull/ are calculated separately by using the combined moment which is determined by stochastic ...The ultimate bending moment and maximal shear stress of a bulk carrier with two structural forms （single hull and double hull/ are calculated separately by using the combined moment which is determined by stochastic process. Then the assessment of reliability is carried out. The results indicate that by introducing the double-hull structure, the shear stress of side can be decreased to half of that of the primary structure（ 50.7% i. but the effect on longitudinal strength is not obvious. Finally, the effects of different double-side skin widths on ultimate bending moment and the maximal shear stress are investigated, followed by proposals of the selection of the double-side skin width.展开更多
The wind-assisted propulsion system is becoming one of the most popular and efficient ways to reduce both fuel consumption and carbon dioxide emission from the ships.In this study,several analyses have been carried ou...The wind-assisted propulsion system is becoming one of the most popular and efficient ways to reduce both fuel consumption and carbon dioxide emission from the ships.In this study,several analyses have been carried out on a model of bulk carrier fitted with five rigid sails with a 180°rotating mechanism for maximum usage of wind power and a telescopic reefing mechanism for folding it during berthing.The stability of the ship has been verified through the calculations of initial stability,static stability,and dynamic stability through the fulfillment of the weather criterion using MAXSURF software.The structural analysis of the sail was carried out in ANSYS static structural module.Several flow simulations were carried out in ANSYS fluent module to predict the thrusts produced by the sails at different apparent wind angles,which would in turn reduce the thrust required from the propeller.In this way,the brake horse powers required for different sail arrangements were analyzed to find out a guideline for this wind propulsion system to generate better powering performances.To consider drift and yaw effect on propulsion system,an MMG mathematical model–based simulation was carried out for different drift angles of motion of the ship considering hard sail–based wind loads.Through these analyses,it has been found out that the hard sail–based wind-assisted propulsion system in some cases have produced a reduction of more than 30%brake power in straight ahead motion and around 20%reduction in case of drifting ships compared to the model having no sails.展开更多
The stress combination method for the fatigue assessment of the hatch comer of a bulk carrier was investigated based on equivalent waves. The principles of the equivalent waves of ship structures were given, including...The stress combination method for the fatigue assessment of the hatch comer of a bulk carrier was investigated based on equivalent waves. The principles of the equivalent waves of ship structures were given, including the determination of the dominant load parameter, heading, frequency, and amplitude of the equivalent regular waves. The dominant load parameters of the hatch comer of a bulk carrier were identified by the structural stress response analysis, and then a series of equivalent regular waves were defined based on these parameters. A combination method of the structural stress ranges under the different equivalent waves was developed for the fatigue analysis. The combination factors were obtained by least square regression analysis with the stress ranges derived from spectral fatigue analysis as the target value. The proposed method was applied to the hatch comer of another bulk carrier as an example. This shows that the results from the equivalent wave approach agree well with those from the spectral fatigue analysis. The workload is reduced substantially. This method can be referenced in the fatigue assessment of the hatch comer of a bulk carrier.展开更多
The paper focuses on the assessment of the hull girder ultimate strength,combined with random pitting corrosion wastage,by the incremental-iterative method.After a brief review about the state of art,the local ultimat...The paper focuses on the assessment of the hull girder ultimate strength,combined with random pitting corrosion wastage,by the incremental-iterative method.After a brief review about the state of art,the local ultimate strength of pitted platings under uniaxial compression is preliminarily outlined and subsequently a closed-form design formula is endorsed in the Rule incremental-iterative method,to account for pitting corrosion wastage in the hull girder ultimate strength check.The ISSC bulk carrier is assumed as reference ship in a benchmark study,devoted to test the effectiveness of the incremental-iterative method,by a comparative analysis with a set of FE simulations,performed by Ansys Mechanical APDL.Four reference cases,with different locations of pitting corrosion wastage,are investigated focusing on nine combinations of pitting and corrosion intensity degrees.Finally,a comparative analysis between the hull girder ultimate strength,combined with pitting corrosion wastage,and the relevant values,complying with the Rule net scantling approach,is performed.Based on current results,the modified incremental-iterative method allows efficiently assessing the hull girder ultimate strength,combined with pitting corrosion wastage,so revealing useful both in the design process of new vessels and in the structural health monitoring of aged ships.展开更多
Nowadays,the development of science and technology brings the innovations and resolutions in aims with increasing the benefits and incomes for companies and producers.Additionally,the development of nation’s economic...Nowadays,the development of science and technology brings the innovations and resolutions in aims with increasing the benefits and incomes for companies and producers.Additionally,the development of nation’s economic associates with environmental protection.In the field of shipping transportation,the increasing in a number of ships operates then International Maritime Organization IMO’s regulations become gradually more tightly about the environmental protection.EEOI-Energy Efficiency Operational Indicator is an operational measure tool for assessing the ship energy efficiency and CO 2 emission to the environment.Furthermore,the research status is about ships energy efficiency management also has the optimistic trends and more effective.In the world,there are a lot of ships energy efficiency researches in aim with enhancing the energy efficiency and environmental protection.For instance,the voyage optimization,increasing the propulsion efficiency of ships,reducing the resistances,etc.However,in Vietnam,there are a lot of shipping transportation companies with different types of ship but the number of research about ships energy efficiency management also restrict.Since this research was carried out and applied the energy efficiency measure tool of International Maritime Organization(IMO)for assessing all ships in Vietnam.The above workings were conducted by EEOI calculation tool for a certain ship with name M/V NSU JUSTICE 250,000 DWT of the VINIC Shipping Transportation Company,Vietnam.展开更多
文摘This paper deals with modeling corrosion wastage over the fuel tanks＇ structures at the exemplar of ten aged bulk carriers. In this paper, employed method might be treated as a long term one, and it is based on Weibull distribution parameters analysis. The purpose of these analyses is optimal assessing of the average corrosion losses for the bulk carriers＇ fuel tanks areas at different points of time during the whole period of the exploitation, due to uprising the structural stability and safety of bulk carriers in operation. Though, the applied approach, among others, might be of particular importance in determining the amounts （percentage/depths） of time-dependent corrosion losses over different areas of aging bulk carriers＇ fuel tanks during the operational circles, with the ultimate goal of keeping stability and safety of these vital vessels＇ structural components.
文摘In this paper, well-known and structured Monte Carlo simulation technique has been employed in predicting the amounts of the corrosion wastage over some bulk carriers＇ structural elements in different points of time during their exploitation life. As a base for the realization of the simulations, the appropriate statistical data collected over the group of ten bulk carriers have been used. Both longitudinal and transversal ships＇ hull structural elements have been taken into the consideration. Due to some experts＇ knowledge in this domain, the critical hull zones are identified and certain interventions are done in the pre-processing of the input data to the Monte Carlo simulations, all with the aim of achieving better convergence between simulation results and the experts＇ expectations in this field.
文摘The world is facing great challenges regarding the energy crisis and environmental pollution.One of the main challenges is the increasing number of ships with a lot of different types and sizes.In this research,it is essential to analyze the operational energy efficiency of sea-going ships since the previous studies have concentrated on the inland river ships.This working is carried out by analyzing of the energy efficiency operation for large size ships such as bulk carriers,container ships,etc.based on the resistance characteristics of different navigation environment factors.A numerical model of main engine energy efficiency operation was considered using the energy efficiency measure of IMO(International Maritime Organization),in particular using the Energy Efficiency Operational Indicator(EEOI)as a monitoring tool in this research.This EEOI numerical model was established and simulated through Simulink/Matlab and verified by the collected data from a certain vessel in Vietnam.The EEOI model was simulated under the different navigation environment conditions including various engine speed,wind speed,wave height,and water speed.After that,the simulation results of this research will be compared with experimental database of a certain bulk carrier namely M/V NSU JUSTICE 250,000 DWT.The results indicated that it is important to consider the main engine speed appropriately in ship operation in order to save energy onboard and reduce the greenhouse gas emission problem.
文摘The ship energy efficiency management is an important topic in the field of the energy management onboard and the exhaust gases emission nowadays.The advanced model plays a vital role to improve the ship energy efficiency management when considering the variable factors.The establishment of the ship energy efficiency model through energy efficiency operational indicator(EEOI)index has been conducted through Monte Carlo simulation method along with using the operation data of a bulk carrier.A bulk carrier is chosen,namely,M/V NSU JUSTICE 250,000 DWT of VINIC Shipping Transportation Company in Vietnam.This research uses the real operational data to perform a statistical methodology which calculates the various factors used to calculate EEOI.This method is supported by Matlab program through the curve fitting tool.The normal distribution estimation and the kernel density estimation method are used for the parametric curve fitting and non-parametric curve fitting,respectively.The average weather condition(wind speed and wave height)and the fouling condition of hull have been investigated and compared with the research results.The validation of the proposed methods has been conducted through the study of the external factors influencing the research results.The research result shows the optimal operational data for the fuel consumption at each certain voyage.This paper is useful for the ship-owners and the ship-operators in the field of the ship energy efficiency management.
文摘Evolutionary algorithm is applied as an optimization method in this paper. The increment of cumulative failure probability of fatigue, inspection cost, inspection interval and means are adopted as limiting condition, objective function and optimization variable respectively. According to fatigue characteristics of ship structure, the optimization research of inspecting fatigue deteriorating is carried out. The optimal inspection planning of minimal inspection cost is chosen. An example of computation and comparison of inspection plans is given. The results demonstrate that an optimal inspection plan considering security and economics can be chosen by the means in this paper.
文摘The ultimate bending moment and maximal shear stress of a bulk carrier with two structural forms （single hull and double hull/ are calculated separately by using the combined moment which is determined by stochastic process. Then the assessment of reliability is carried out. The results indicate that by introducing the double-hull structure, the shear stress of side can be decreased to half of that of the primary structure（ 50.7% i. but the effect on longitudinal strength is not obvious. Finally, the effects of different double-side skin widths on ultimate bending moment and the maximal shear stress are investigated, followed by proposals of the selection of the double-side skin width.
文摘The wind-assisted propulsion system is becoming one of the most popular and efficient ways to reduce both fuel consumption and carbon dioxide emission from the ships.In this study,several analyses have been carried out on a model of bulk carrier fitted with five rigid sails with a 180°rotating mechanism for maximum usage of wind power and a telescopic reefing mechanism for folding it during berthing.The stability of the ship has been verified through the calculations of initial stability,static stability,and dynamic stability through the fulfillment of the weather criterion using MAXSURF software.The structural analysis of the sail was carried out in ANSYS static structural module.Several flow simulations were carried out in ANSYS fluent module to predict the thrusts produced by the sails at different apparent wind angles,which would in turn reduce the thrust required from the propeller.In this way,the brake horse powers required for different sail arrangements were analyzed to find out a guideline for this wind propulsion system to generate better powering performances.To consider drift and yaw effect on propulsion system,an MMG mathematical model–based simulation was carried out for different drift angles of motion of the ship considering hard sail–based wind loads.Through these analyses,it has been found out that the hard sail–based wind-assisted propulsion system in some cases have produced a reduction of more than 30%brake power in straight ahead motion and around 20%reduction in case of drifting ships compared to the model having no sails.
基金Supported by the National Natural Science Foundation of China （50809019）.
文摘The stress combination method for the fatigue assessment of the hatch comer of a bulk carrier was investigated based on equivalent waves. The principles of the equivalent waves of ship structures were given, including the determination of the dominant load parameter, heading, frequency, and amplitude of the equivalent regular waves. The dominant load parameters of the hatch comer of a bulk carrier were identified by the structural stress response analysis, and then a series of equivalent regular waves were defined based on these parameters. A combination method of the structural stress ranges under the different equivalent waves was developed for the fatigue analysis. The combination factors were obtained by least square regression analysis with the stress ranges derived from spectral fatigue analysis as the target value. The proposed method was applied to the hatch comer of another bulk carrier as an example. This shows that the results from the equivalent wave approach agree well with those from the spectral fatigue analysis. The workload is reduced substantially. This method can be referenced in the fatigue assessment of the hatch comer of a bulk carrier.
基金Open access funding provided by Universita Parthenope di Napoli within the CRUI-CARE Agreement.
文摘The paper focuses on the assessment of the hull girder ultimate strength,combined with random pitting corrosion wastage,by the incremental-iterative method.After a brief review about the state of art,the local ultimate strength of pitted platings under uniaxial compression is preliminarily outlined and subsequently a closed-form design formula is endorsed in the Rule incremental-iterative method,to account for pitting corrosion wastage in the hull girder ultimate strength check.The ISSC bulk carrier is assumed as reference ship in a benchmark study,devoted to test the effectiveness of the incremental-iterative method,by a comparative analysis with a set of FE simulations,performed by Ansys Mechanical APDL.Four reference cases,with different locations of pitting corrosion wastage,are investigated focusing on nine combinations of pitting and corrosion intensity degrees.Finally,a comparative analysis between the hull girder ultimate strength,combined with pitting corrosion wastage,and the relevant values,complying with the Rule net scantling approach,is performed.Based on current results,the modified incremental-iterative method allows efficiently assessing the hull girder ultimate strength,combined with pitting corrosion wastage,so revealing useful both in the design process of new vessels and in the structural health monitoring of aged ships.
文摘Nowadays,the development of science and technology brings the innovations and resolutions in aims with increasing the benefits and incomes for companies and producers.Additionally,the development of nation’s economic associates with environmental protection.In the field of shipping transportation,the increasing in a number of ships operates then International Maritime Organization IMO’s regulations become gradually more tightly about the environmental protection.EEOI-Energy Efficiency Operational Indicator is an operational measure tool for assessing the ship energy efficiency and CO 2 emission to the environment.Furthermore,the research status is about ships energy efficiency management also has the optimistic trends and more effective.In the world,there are a lot of ships energy efficiency researches in aim with enhancing the energy efficiency and environmental protection.For instance,the voyage optimization,increasing the propulsion efficiency of ships,reducing the resistances,etc.However,in Vietnam,there are a lot of shipping transportation companies with different types of ship but the number of research about ships energy efficiency management also restrict.Since this research was carried out and applied the energy efficiency measure tool of International Maritime Organization(IMO)for assessing all ships in Vietnam.The above workings were conducted by EEOI calculation tool for a certain ship with name M/V NSU JUSTICE 250,000 DWT of the VINIC Shipping Transportation Company,Vietnam.
