Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for a ferry during operation.The emission factor for nitrogen...Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for a ferry during operation.The emission factor for nitrogen oxides is lower than what is typically found for marine gasoil but does not reach the tier III limit.The emissions of particulate matter are significantly lower than for fuel oils and similar to what is found for LNG engines.The main part of the particles can be found in the ultrafine range with the peak being at around 18 nm.About 93%of the particles are evaporated and absorbed when using a thermodenuder,and thus a large majority of the particles are volatile.Methanol is a potential future marine fuel that will reduce emissions of air pollutants and can be made as a biofuel to meet emission targets for greenhouse gases.展开更多
Based on the ArcGIS geographic information system and the ORACLE database management system,this paper reports our studies on the technology of Marine Engineering Geological Exploration Information System(MEGEIS). By ...Based on the ArcGIS geographic information system and the ORACLE database management system,this paper reports our studies on the technology of Marine Engineering Geological Exploration Information System(MEGEIS). By analyzing system structure,designing function modules and discussing data management,this paper systematically proposes a framework of technol-ogy to integrate,manage,and analyze the seabed information comprehensively. Then,the technology is applied to the design and development of the Bohai Sea Oilfield Paradigm Area Information System. The system can not only meet the practical demands of marine resources exploration and exploitation in the Bohai Sea oilfield,but also serve as a preparatory work in theory and technology for the realization of the 'Digital Seabed'.展开更多
In power production,gas turbines are commonly used components that generate high amount of energy depending on size and weight.They function as integral parts of helicopters,aircrafts,trains,ships,electrical generator...In power production,gas turbines are commonly used components that generate high amount of energy depending on size and weight.They function as integral parts of helicopters,aircrafts,trains,ships,electrical generators,and tanks.Notably,many researchers are focusing on the design,operation,and maintenance of gas turbines.The focal point of this paper is a DEMATEL approach based on fuzzy sets,with the attempt to use these fuzzy sets explicitly.Using this approach,the cause–effect diagram of gas turbine failures expressed in the literature is generated and aimed to create a perspective for operators.The results of the study show that,"connecting shaft has been broken between turbine and gear box"selected the most important cause factor and"sufficient pressure fuel does not come for fuel pump"is selected the most important effect factor,according to the experts.展开更多
NIN has developed a new type of Ti alloy. It is suitable for structure pieces applied in hightemperature and high-pressure water/steam conditions. Its nominal composition is Ti-4Al-2V. In this paper, its microstructu...NIN has developed a new type of Ti alloy. It is suitable for structure pieces applied in hightemperature and high-pressure water/steam conditions. Its nominal composition is Ti-4Al-2V. In this paper, its microstructure, mechanical properties and corrosion resistance were studied in detail.展开更多
According to the conductivity test results,it is found that oil conductivity increases with an increasing additive content,and the turbidity of engine oil is also augmented with an increasing additive content.After te...According to the conductivity test results,it is found that oil conductivity increases with an increasing additive content,and the turbidity of engine oil is also augmented with an increasing additive content.After testing the turbidity and stability of oils containing the typical conventional calcium sulfonate,the overbased calcium sulfonate and the mixture of the above two calcium sulfonates,the results show that at the same amount of additives used,the oil with a higher turbidity demonstrated a worse stability.A nonionic dispersant that was added into lube oils at a definite concentration could improve the detergent compatibility.For this reason,the sediment volume in three kinds of oils all decreased obviously,resulting in successful improvement of storage stability of marine engine oils.展开更多
This study aims to determine the awareness and opinions on Clean Air Act among marine engineering students at maritime university,specifically,John B.Lacson Foundation Maritime University-Molo,Iloilo City,Philippines....This study aims to determine the awareness and opinions on Clean Air Act among marine engineering students at maritime university,specifically,John B.Lacson Foundation Maritime University-Molo,Iloilo City,Philippines.The participants of this study were 30 marine engineering students of the maritime university,especially JBLFMU-Molo for school year 2014-2015.Participants of the study were enrolled at the College of Maritime Education,JBLFMU-Molo,Iloilo City,Philippines.The researchers employed quantitative research design.The respondents’comments,suggestions,observations,and remarks on the perceived awareness and opinions on Clean Air Act were captured in this study.After gathering the qualitative information,the researchers classified and categorized the write-ups of the respondents into different categories.The results reveal that the participants of the present study were aware of the Clean Air Act as an entire group and when classified according to different categories.Most of the participants said that Clean Air Act protects the environment,followed by the participants who said that Clean Air Act can prevent air pollution.Next,in rank,the participants who said“it is good because you can go everywhere to inhale fresh air,followed by participants who said Clean Air Act can reduce the things that can harm the ozone layer,the last participants said that they never heard of Clean Air Act.展开更多
With the gradual deepening of the internationalization of the seamen's labor market, more and more shipowners and ship management companies pay attention to the seamen's English listening, speaking and reading...With the gradual deepening of the internationalization of the seamen's labor market, more and more shipowners and ship management companies pay attention to the seamen's English listening, speaking and reading ability. English has obviously become the main working language on ocean-going ships. Apart from being able to communicate smoothly in English, the crew must also have certain writing and reading skills. "Marine Engineering English" is a professional course specially designed to improve engineers' reading and writing ability. Based on the characteristics of this course, this paper summarizes the representative grammatical structures and discusses how to improve reading comprehension through long sentence analysis.展开更多
Pre-chamber ignition technology can address the issue of uneven in-cylinder mixture combustion in large-bore marine engines.The impact of various pre-chamber structures on the formation of the mixture and jet flames w...Pre-chamber ignition technology can address the issue of uneven in-cylinder mixture combustion in large-bore marine engines.The impact of various pre-chamber structures on the formation of the mixture and jet flames within the pre-chamber is explored.This study performed numerical simulations on a large-bore marine ammonia/hydrogen pre-chamber engine prototype,considering pre-chamber volume,throat diameter,the distance between the hydrogen injector and the spark plug,and the hydrogen injector angle.Compared with the original engine,when the pre-chamber volume is 73.4 ml,the throat diameter is 14 mm,the distance ratio is 0.92,and the hydrogen injector angle is 80°.Moreover,the peak pressure in the pre-chamber increased by 23.1%,and that in the main chamber increased by 46.3%.The results indicate that the performance of the original engine is greatly enhanced by altering its fuel and pre-chamber structure.展开更多
This paper argues that in an era of accelerating climate change and rising sea levels,what truly matters is not merely the marine structure itself,but the foresight and adaptability embedded in its conception.As globa...This paper argues that in an era of accelerating climate change and rising sea levels,what truly matters is not merely the marine structure itself,but the foresight and adaptability embedded in its conception.As global urbanization intensifies along coastlines,and as storms grow stronger and ecosystems degrade,there is an urgent need for transformative approaches to ocean engineering and design.We introduce Terrestrial Education,an interdisciplinary framework that moves beyond conventional sustainability models by integrating ecological intelligence,regenerative systems thinking,and advanced technologies.Unlike traditional approaches that focus on minimizing harm,Terrestrial Education emphasizes active ecological restoration,socio-technical evolution,and planetary stewardship.Drawing on lessons from space exploration,such as closed-loop life support systems,autonomous environmental management,and modular habitat design,we demonstrate how these principles can inspire resilient marine infrastructures,including floating platforms,submerged laboratories,and biointegrated offshore structures.These designs are envisioned not only for their physical durability but also for their capacity to regenerate ecosystems and foster meaningful human interaction with marine environments.The paper highlights key priorities such as adaptability to climate extremes,energy efficiency through marine renewables,and environmental integration using biomimetic materials.By aligning with the Sustainable Development Goals of the blue economy,Terrestrial Education offers a future-oriented model that harmonizes environmental,technological,and economic objectives.Ultimately,this framework provides a conceptual and operational foundation for reimagining marine structures as catalysts for innovation,educational transformation,and resilient planetary futures in the climate era.展开更多
Misfire is a common fault in compression ignition engines,characterized by the absence or flame loss due to insufficient fuel in the cylinders.This fault is difficult to diagnose and resolve due to its multiple potent...Misfire is a common fault in compression ignition engines,characterized by the absence or flame loss due to insufficient fuel in the cylinders.This fault is difficult to diagnose and resolve due to its multiple potential causes.This study focuses on identifying misfires in a 12-cylinder V-type marine diesel engine by analyzing vibration data collected from 15 accelerometers mounted on the engine block.Three machine learning algorithms—K-Nearest Neighbors(K-NNs),support vector machines(SVMs),and random forests(RFs)—were employed to classify engine conditions using 18 time-domain features.Results showed that the K-NN,SVM and RF algorithms achieved F1 scores of 99.87%,100%,and 99.87%,respectively,when using 18 time-domain features and all 15 accelerometers mounted on the engine block.Additionally,the study evaluated classification performance while reducing the number of accelerometers and features using two methods:Relief-F and general combinatory analysis(GCA).Although the GCA method yields better results when using only two accelerometers and nine features for misfire classification,its overall process required substantially more computational time compared to Relief-F.The best result obtained with Relief-F was achieved using 3 accelerometers and 18 features.Therefore,Relief-F proved to be more practical and take less overall computational time within the proposed framework.展开更多
In order to reduce the pollutant emission and alleviate the pressure of petroleum resources shortage and greenhouse gas emission at the same time,the use of clean and renewable alternative fuel for marine engines is a...In order to reduce the pollutant emission and alleviate the pressure of petroleum resources shortage and greenhouse gas emission at the same time,the use of clean and renewable alternative fuel for marine engines is a promising option.In this study,a marine diesel engine,which was modified to run in diesel methanol compound combustion (DMCC) mode,was investigated.After the diesel injection parameters were calibrated,and combined with a sample after-treatment device DOC (diesel oxidation catalyst),the engine could meet the requirements of China II legislation.The overall MSP (methanol substitute percent) reached 54.1%.The value of each pollutant emission was much lower than that in China II emission legislation,and there was almost no methanol and formaldehyde emissions.When methanol was injected into the inlet manifold,the intake air temperature decreased a lot,as well as the exhaust gas temperature,which were beneficial to increase engine thermal efficiency and improve engine room environment.Compared with the engine running in pure diesel mode,when the engine ran in diesel/methanol dual fuel mode,the combustion phase was advanced,and the combustion duration became shorter.Therefore,the engine thermal efficiency increased,and fuel consumption decreased significantly.展开更多
The development of maritime trade has greatly promoted the development of diesel engines.However,with the increasingly serious environmental problems,more and more attention has been paid to the exhaust emissions of h...The development of maritime trade has greatly promoted the development of diesel engines.However,with the increasingly serious environmental problems,more and more attention has been paid to the exhaust emissions of high-power marine diesel engines.The restrictions on SOx have been implemented globally,and the limitation of the NO,will be the next priority.This paper illustrates(a)Principle and research progress of NOx emissions-reduction technology of marine diesel engine;(b)Summary of advantages and disadvantages among various reduction technologies and their reduction effects;(c)The application effect of mainstream technology on board.Firstly,since exhaust gas recirculation(EGR)can achieve Tier-Ⅲ directly from Tier-Ⅰ without considering the increased fuel consumption.It is deemed as the most promising technology to reduce emissions by controlling combustion condition.However,EGR has shortcomings of excessive increase in ftiel consumption and generation of waste water,which need to be solved immediately.Secondly,selective catalytic reduction(SCR)is the most effective and straightforward means to achieve Tier-Ⅲ.Despite of the continuous optimization of SCR unit volume,the problem of scrap catalyst seriously limits its wide application.How to match the supercharger more efficiently is a key factor in choosing between high and low pressure SCR.Thirdly,nature gas(NG)engines are capable of achieving a reduction in NOx,but in order to meet the requirements of Tier-Ⅲ,it still needs to be assisted by other technologies.The emissions of hydrocarbon(HC)and CO in NG engines are huge defects that must be solved.Lastly,technologies such as the Miller cycle,Two-stage supercharging and mixed-water combustion can also reduce emissions but were rarely used alone.These technologies can be combined with EGR,SCR and NG engines to optimize the enginesJ economy and emission characteristics.展开更多
Longitudinal vibration,torsional vibration and their coupled vibration are the main vibration modes of the crankshaft-sliding bearing system.However,these vibrations of the propeller-crankshaft-sliding bearing system ...Longitudinal vibration,torsional vibration and their coupled vibration are the main vibration modes of the crankshaft-sliding bearing system.However,these vibrations of the propeller-crankshaft-sliding bearing system generated by the fluid exciting force on the propeller are much more complex.Currently,the torsional and longitudinal vibrations have been studied separately while the research on their coupled vibration is few,and the influence of the propeller structure to dynamic characteristics of a crankshaft has not been studied yet.In order to describe the dynamic properties of a crankshaft accurately,a nonlinear dynamic model is proposed taking the effect of torsional-longitudinal coupling and the variable inertia of propeller,connecting rod and piston into account.Numerical simulation cases are carried out to calculate the response data of the system in time and frequency domains under the working speed and over-speed,respectively.Results of vibration analysis of the propeller and crankshaft system coupled in torsional and longitudinal direction indicate that the system dynamic behaviors are relatively complicated especially in the components of the frequency response.For example,the 4 times of an exciting frequency acting on the propeller by fluid appears at 130 r/min,while not yield at 105 r/min.While the possible abnormal vibration at over-speed just needs to be vigilant.So when designing the propeller shafting used in marine diesel engines,strength calculation and vibration analysis based only on linear model may cause great errors and the proposed research provides some references to design diesel engine propeller shafting used in large marines.展开更多
Natural gas/diesel dual-fuel combustion strategy has a great potential to reduce emissions for marine engines while the high fuel consumption is the major problem.Pre-chamber system is commonly employed as the ignitio...Natural gas/diesel dual-fuel combustion strategy has a great potential to reduce emissions for marine engines while the high fuel consumption is the major problem.Pre-chamber system is commonly employed as the ignition system on large-bore dual-fuel marine engines especially under lean-burn condition,due to its advanced ignition stability and engine efficiency.However,the ignition and combustion mechanism in such dual-fuel pre-chamber engine is still unclear and the effects of in-cylinder swirl flow and mixture stratification on combustion require further investigation specifically.This paper numerically studied the detailed ignition mechanism and combustion process in a marine engine equipped with a pre-chamber ignition system,and revealed the flame development process in main chamber.Moreover,the effects of mixture stratification and swirl ratio on the combustion rate and further engine thermal efficiency are investigated under decoupled condition.The results mainly show that the jet flame develops along the pre-chamber orifice centerline at the initial stage and premixed combustion play an important role,while after that,heat release zone only exist at flame surface,and premixed flame propagation controls the combustion process.In addition,with higher swirl ratio the combustion rate increases significantly due to the wider ignition area.Mixture stratification degree plays a role in accelerating the combustion,either too high or too low stratification degree reduce the combustion rate,while a moderate stratification increases the combustion rate.And appropriate stratification degree by verifying the gas injection parameters can reduce fuel consumption in 0.3%.展开更多
High-pressure direct-injection (HPDI) of natu- ral gas is one of the most promising solutions for future ship engines, in which the combustion process is mainly controlled by the chemical kinetics. However, the employ...High-pressure direct-injection (HPDI) of natu- ral gas is one of the most promising solutions for future ship engines, in which the combustion process is mainly controlled by the chemical kinetics. However, the employment of detailed chemical models for the multi-dimensional combustion simulation is significantly expensive due to the large scale of the marine engine. In the present paper, a reduced n-heptane/methane model consisting of 35-step reactions was constructed using multiple reduction approaches. Then this model was further reduced to include only 27 reactions by utilizing the HyChem (Hybrid Chemistry) method. An overall good agreement with the experimentally measured ignition delay data of both n-heptane and methane for these two reduced models was achieved and reasonable predictions for the measured laminar flame speeds were obtained for the 35-step model. But the 27-step model cannot predict the laminar flame speed very well. In addition, these two reduced models were both able to reproduce the experimentally measured in-cylinder pressure and heat release rate profiles for a HPDI natural gas marine engine, the highest error of predicted combustion phase being 6.5%. However, the engine-out CO emission was over-predicted and the highest error of predicted NOx emission was less than 12.9%. The predicted distributions of temperature and equivalence ratio by the 35-step and 27-step models are similar to those of the 334-step model. However, the predicted distributions of OH and CH2O are significantly different from those of the 334-step model. In short, the reduced chemical kinetic models developed provide a high-efficient and dependable method to simulate the characteristics of combustion and emissions in HPDI natural gas marine engines.展开更多
This paper focuses on the creation of a dynamic probabilistic model which simulates deterioration trends of a marine engine lubricationsystem. The approach is based on risk and the implementation is achieved through a...This paper focuses on the creation of a dynamic probabilistic model which simulates deterioration trends of a marine engine lubricationsystem. The approach is based on risk and the implementation is achieved through a dynamic Bayesian network (dBN).Risk can be useful for decision making, while dBNs are a powerful tool for risk modelling and prediction models. The model takesinto account deterioration of engine components, oil degradation and the off-line condition monitoring technique of oil analysis, inthe context of predictive maintenance. The paper aims to efficiently predict probability evolution for main engine lubrication failureand to decide upon the most beneficial schemes from a variety of lubrication oil analysis interval schemes by introducing monetarycosts and producing the risk model. Real data and respective analysis, along with expert elicitation, are utilized for achieving modelquantification, while themodel is materialized through a code in the Matlab environment. Results from the probabilistic model showa realistic simulation for the system and indicate the obvious, that with more frequent oil analyses and respective maintenance orrepairs, the probability of failure drops significantly. However, the results from the risk model highlight that the costs can redefinescheme suggestions, as they can correspond to low probabilities of failure but also to higher costs. A two-month interval scheme issuggested, in contrast to the most preferred practice among shipping companies of a three-month interval. The developed model isin general identified as a failure prediction tool focusing on marine engine lubrication failure.展开更多
Human error,an important factor,may lead to serious results in various operational fields.The human factor plays a critical role in the risks and hazards of the maritime industry.A ship can achieve safe navigation whe...Human error,an important factor,may lead to serious results in various operational fields.The human factor plays a critical role in the risks and hazards of the maritime industry.A ship can achieve safe navigation when all operations in the engine room are conducted vigilantly.This paper presents a systematic evaluation of 20 failures in auxiliary systems of marine diesel engines that may be caused by human error.The Cognitive Reliability Error Analysis Method(CREAM)is used to determine the potentiality of human errors in the failures implied thanks to the answers of experts.Using this method,the probabilities of human error on failures were evaluated and the critical ones were emphasized.The measures to be taken for these results will make significant contributions not only to the seafarers but also to the ship owners.展开更多
In the organizational context of marine engineering,employee individual often prefers to concentrate herself to the day-to-day routine job,but to shirk the responsibilities of the Information Security Policies(ISPs)co...In the organizational context of marine engineering,employee individual often prefers to concentrate herself to the day-to-day routine job,but to shirk the responsibilities of the Information Security Policies(ISPs)compliance,after she has been delegated by the employer to perform the two different tasks in the same time period.This would lead to negative influences on the security of marine information systems and the employee’s routine job performance.In view of the task structures of employee’s routine job and marine ISPs compliance,the variables of emphasis on scheduling are incorporated into a multi-task principal-agent model to explore the optimal incentive scheme to motivate and control the employees to select appropriate effort levels for conducting the two highly structured tasks.The role of emphasis on scheduling on the incentive intensities for the two tasks have been clarified through modeling and simulation,and the corresponding incentive tactics are suggested.The new two-task incentive scheme is expected to provide useful insight for understanding and controlling marine engineering employee’s routine job and ISPs compliance behavior.展开更多
This paper presents a simulator model of a marine diesel engine based on physical, semi-physical, mathematical and thermodynamic equations, which allows fast predictive simulations The whole engine system is divided i...This paper presents a simulator model of a marine diesel engine based on physical, semi-physical, mathematical and thermodynamic equations, which allows fast predictive simulations The whole engine system is divided into several functional blocks： cooling, lubrication, air, injection, combustion and emissions. The sub-models and dynamic characteristics of individual blocks are established according to engine working principles equations and experimental data collected from a marine diesel engine test bench for SIMB Company under the reference 6M26SRP1. The overall engine system dynamics is expressed as a set of simultaneous algebraic and differential equations using sub-blocks and S-Functions of Matlab/Simulink. The simulation of this model, implemented on Matlab/Simulink has been validated and can be used to obtain engine performance, pressure, temperature, efficiency, heat release, crank angle, fuel rate, emissions at different sub-blocks. The simulator will be used, in future work, to study the engine performance in faulty conditions, and can be used to assist marine engineers in fault diagnosis and estimation （FDI） as well as designers to predict the behavior of the cooling system, lubrication system, injection system, combustion, emissions, in order to optimize the dimensions of different components. This program is a platform for fault simulator, to investigate the impact on sub-blocks engine＇s output of changing values for faults parameters such as： faulty fuel injector, leaky cylinder, worn fuel pump, broken piston rings, a dirty turbocharger, dirty air filter, dirty air cooler, air leakage, water leakage, oil leakage and contamination, fouling of heat exchanger, pumps wear, failure of injectors （and many others）.展开更多
文摘Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for a ferry during operation.The emission factor for nitrogen oxides is lower than what is typically found for marine gasoil but does not reach the tier III limit.The emissions of particulate matter are significantly lower than for fuel oils and similar to what is found for LNG engines.The main part of the particles can be found in the ultrafine range with the peak being at around 18 nm.About 93%of the particles are evaporated and absorbed when using a thermodenuder,and thus a large majority of the particles are volatile.Methanol is a potential future marine fuel that will reduce emissions of air pollutants and can be made as a biofuel to meet emission targets for greenhouse gases.
文摘Based on the ArcGIS geographic information system and the ORACLE database management system,this paper reports our studies on the technology of Marine Engineering Geological Exploration Information System(MEGEIS). By analyzing system structure,designing function modules and discussing data management,this paper systematically proposes a framework of technol-ogy to integrate,manage,and analyze the seabed information comprehensively. Then,the technology is applied to the design and development of the Bohai Sea Oilfield Paradigm Area Information System. The system can not only meet the practical demands of marine resources exploration and exploitation in the Bohai Sea oilfield,but also serve as a preparatory work in theory and technology for the realization of the 'Digital Seabed'.
文摘In power production,gas turbines are commonly used components that generate high amount of energy depending on size and weight.They function as integral parts of helicopters,aircrafts,trains,ships,electrical generators,and tanks.Notably,many researchers are focusing on the design,operation,and maintenance of gas turbines.The focal point of this paper is a DEMATEL approach based on fuzzy sets,with the attempt to use these fuzzy sets explicitly.Using this approach,the cause–effect diagram of gas turbine failures expressed in the literature is generated and aimed to create a perspective for operators.The results of the study show that,"connecting shaft has been broken between turbine and gear box"selected the most important cause factor and"sufficient pressure fuel does not come for fuel pump"is selected the most important effect factor,according to the experts.
文摘NIN has developed a new type of Ti alloy. It is suitable for structure pieces applied in hightemperature and high-pressure water/steam conditions. Its nominal composition is Ti-4Al-2V. In this paper, its microstructure, mechanical properties and corrosion resistance were studied in detail.
文摘According to the conductivity test results,it is found that oil conductivity increases with an increasing additive content,and the turbidity of engine oil is also augmented with an increasing additive content.After testing the turbidity and stability of oils containing the typical conventional calcium sulfonate,the overbased calcium sulfonate and the mixture of the above two calcium sulfonates,the results show that at the same amount of additives used,the oil with a higher turbidity demonstrated a worse stability.A nonionic dispersant that was added into lube oils at a definite concentration could improve the detergent compatibility.For this reason,the sediment volume in three kinds of oils all decreased obviously,resulting in successful improvement of storage stability of marine engine oils.
文摘This study aims to determine the awareness and opinions on Clean Air Act among marine engineering students at maritime university,specifically,John B.Lacson Foundation Maritime University-Molo,Iloilo City,Philippines.The participants of this study were 30 marine engineering students of the maritime university,especially JBLFMU-Molo for school year 2014-2015.Participants of the study were enrolled at the College of Maritime Education,JBLFMU-Molo,Iloilo City,Philippines.The researchers employed quantitative research design.The respondents’comments,suggestions,observations,and remarks on the perceived awareness and opinions on Clean Air Act were captured in this study.After gathering the qualitative information,the researchers classified and categorized the write-ups of the respondents into different categories.The results reveal that the participants of the present study were aware of the Clean Air Act as an entire group and when classified according to different categories.Most of the participants said that Clean Air Act protects the environment,followed by the participants who said that Clean Air Act can prevent air pollution.Next,in rank,the participants who said“it is good because you can go everywhere to inhale fresh air,followed by participants who said Clean Air Act can reduce the things that can harm the ozone layer,the last participants said that they never heard of Clean Air Act.
文摘With the gradual deepening of the internationalization of the seamen's labor market, more and more shipowners and ship management companies pay attention to the seamen's English listening, speaking and reading ability. English has obviously become the main working language on ocean-going ships. Apart from being able to communicate smoothly in English, the crew must also have certain writing and reading skills. "Marine Engineering English" is a professional course specially designed to improve engineers' reading and writing ability. Based on the characteristics of this course, this paper summarizes the representative grammatical structures and discusses how to improve reading comprehension through long sentence analysis.
基金Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions under Grant No.014000319/2018-00391.
文摘Pre-chamber ignition technology can address the issue of uneven in-cylinder mixture combustion in large-bore marine engines.The impact of various pre-chamber structures on the formation of the mixture and jet flames within the pre-chamber is explored.This study performed numerical simulations on a large-bore marine ammonia/hydrogen pre-chamber engine prototype,considering pre-chamber volume,throat diameter,the distance between the hydrogen injector and the spark plug,and the hydrogen injector angle.Compared with the original engine,when the pre-chamber volume is 73.4 ml,the throat diameter is 14 mm,the distance ratio is 0.92,and the hydrogen injector angle is 80°.Moreover,the peak pressure in the pre-chamber increased by 23.1%,and that in the main chamber increased by 46.3%.The results indicate that the performance of the original engine is greatly enhanced by altering its fuel and pre-chamber structure.
文摘This paper argues that in an era of accelerating climate change and rising sea levels,what truly matters is not merely the marine structure itself,but the foresight and adaptability embedded in its conception.As global urbanization intensifies along coastlines,and as storms grow stronger and ecosystems degrade,there is an urgent need for transformative approaches to ocean engineering and design.We introduce Terrestrial Education,an interdisciplinary framework that moves beyond conventional sustainability models by integrating ecological intelligence,regenerative systems thinking,and advanced technologies.Unlike traditional approaches that focus on minimizing harm,Terrestrial Education emphasizes active ecological restoration,socio-technical evolution,and planetary stewardship.Drawing on lessons from space exploration,such as closed-loop life support systems,autonomous environmental management,and modular habitat design,we demonstrate how these principles can inspire resilient marine infrastructures,including floating platforms,submerged laboratories,and biointegrated offshore structures.These designs are envisioned not only for their physical durability but also for their capacity to regenerate ecosystems and foster meaningful human interaction with marine environments.The paper highlights key priorities such as adaptability to climate extremes,energy efficiency through marine renewables,and environmental integration using biomimetic materials.By aligning with the Sustainable Development Goals of the blue economy,Terrestrial Education offers a future-oriented model that harmonizes environmental,technological,and economic objectives.Ultimately,this framework provides a conceptual and operational foundation for reimagining marine structures as catalysts for innovation,educational transformation,and resilient planetary futures in the climate era.
文摘Misfire is a common fault in compression ignition engines,characterized by the absence or flame loss due to insufficient fuel in the cylinders.This fault is difficult to diagnose and resolve due to its multiple potential causes.This study focuses on identifying misfires in a 12-cylinder V-type marine diesel engine by analyzing vibration data collected from 15 accelerometers mounted on the engine block.Three machine learning algorithms—K-Nearest Neighbors(K-NNs),support vector machines(SVMs),and random forests(RFs)—were employed to classify engine conditions using 18 time-domain features.Results showed that the K-NN,SVM and RF algorithms achieved F1 scores of 99.87%,100%,and 99.87%,respectively,when using 18 time-domain features and all 15 accelerometers mounted on the engine block.Additionally,the study evaluated classification performance while reducing the number of accelerometers and features using two methods:Relief-F and general combinatory analysis(GCA).Although the GCA method yields better results when using only two accelerometers and nine features for misfire classification,its overall process required substantially more computational time compared to Relief-F.The best result obtained with Relief-F was achieved using 3 accelerometers and 18 features.Therefore,Relief-F proved to be more practical and take less overall computational time within the proposed framework.
基金financial support provided by the Natural Science Foundation of China (No.51676134)。
文摘In order to reduce the pollutant emission and alleviate the pressure of petroleum resources shortage and greenhouse gas emission at the same time,the use of clean and renewable alternative fuel for marine engines is a promising option.In this study,a marine diesel engine,which was modified to run in diesel methanol compound combustion (DMCC) mode,was investigated.After the diesel injection parameters were calibrated,and combined with a sample after-treatment device DOC (diesel oxidation catalyst),the engine could meet the requirements of China II legislation.The overall MSP (methanol substitute percent) reached 54.1%.The value of each pollutant emission was much lower than that in China II emission legislation,and there was almost no methanol and formaldehyde emissions.When methanol was injected into the inlet manifold,the intake air temperature decreased a lot,as well as the exhaust gas temperature,which were beneficial to increase engine thermal efficiency and improve engine room environment.Compared with the engine running in pure diesel mode,when the engine ran in diesel/methanol dual fuel mode,the combustion phase was advanced,and the combustion duration became shorter.Therefore,the engine thermal efficiency increased,and fuel consumption decreased significantly.
基金The authors thank the financial support are as follow:Natural Science Foundation Committee of China(No.51709163)China Postdoctoral Science Foundation(No.2018T110382)Shanghai Sailing Program(No.17YF1407500).
文摘The development of maritime trade has greatly promoted the development of diesel engines.However,with the increasingly serious environmental problems,more and more attention has been paid to the exhaust emissions of high-power marine diesel engines.The restrictions on SOx have been implemented globally,and the limitation of the NO,will be the next priority.This paper illustrates(a)Principle and research progress of NOx emissions-reduction technology of marine diesel engine;(b)Summary of advantages and disadvantages among various reduction technologies and their reduction effects;(c)The application effect of mainstream technology on board.Firstly,since exhaust gas recirculation(EGR)can achieve Tier-Ⅲ directly from Tier-Ⅰ without considering the increased fuel consumption.It is deemed as the most promising technology to reduce emissions by controlling combustion condition.However,EGR has shortcomings of excessive increase in ftiel consumption and generation of waste water,which need to be solved immediately.Secondly,selective catalytic reduction(SCR)is the most effective and straightforward means to achieve Tier-Ⅲ.Despite of the continuous optimization of SCR unit volume,the problem of scrap catalyst seriously limits its wide application.How to match the supercharger more efficiently is a key factor in choosing between high and low pressure SCR.Thirdly,nature gas(NG)engines are capable of achieving a reduction in NOx,but in order to meet the requirements of Tier-Ⅲ,it still needs to be assisted by other technologies.The emissions of hydrocarbon(HC)and CO in NG engines are huge defects that must be solved.Lastly,technologies such as the Miller cycle,Two-stage supercharging and mixed-water combustion can also reduce emissions but were rarely used alone.These technologies can be combined with EGR,SCR and NG engines to optimize the enginesJ economy and emission characteristics.
基金Supported by Shanghai Municipal Commission of Economy and Informatization of China(Grant Nos.201001007,2013000016)
文摘Longitudinal vibration,torsional vibration and their coupled vibration are the main vibration modes of the crankshaft-sliding bearing system.However,these vibrations of the propeller-crankshaft-sliding bearing system generated by the fluid exciting force on the propeller are much more complex.Currently,the torsional and longitudinal vibrations have been studied separately while the research on their coupled vibration is few,and the influence of the propeller structure to dynamic characteristics of a crankshaft has not been studied yet.In order to describe the dynamic properties of a crankshaft accurately,a nonlinear dynamic model is proposed taking the effect of torsional-longitudinal coupling and the variable inertia of propeller,connecting rod and piston into account.Numerical simulation cases are carried out to calculate the response data of the system in time and frequency domains under the working speed and over-speed,respectively.Results of vibration analysis of the propeller and crankshaft system coupled in torsional and longitudinal direction indicate that the system dynamic behaviors are relatively complicated especially in the components of the frequency response.For example,the 4 times of an exciting frequency acting on the propeller by fluid appears at 130 r/min,while not yield at 105 r/min.While the possible abnormal vibration at over-speed just needs to be vigilant.So when designing the propeller shafting used in marine diesel engines,strength calculation and vibration analysis based only on linear model may cause great errors and the proposed research provides some references to design diesel engine propeller shafting used in large marines.
基金the financial supports provided by the Low-speed Marine Diesel Project(Project No.CDGC01-KT0308)National Natural Science Foundation of China(Grant No.91941102)。
文摘Natural gas/diesel dual-fuel combustion strategy has a great potential to reduce emissions for marine engines while the high fuel consumption is the major problem.Pre-chamber system is commonly employed as the ignition system on large-bore dual-fuel marine engines especially under lean-burn condition,due to its advanced ignition stability and engine efficiency.However,the ignition and combustion mechanism in such dual-fuel pre-chamber engine is still unclear and the effects of in-cylinder swirl flow and mixture stratification on combustion require further investigation specifically.This paper numerically studied the detailed ignition mechanism and combustion process in a marine engine equipped with a pre-chamber ignition system,and revealed the flame development process in main chamber.Moreover,the effects of mixture stratification and swirl ratio on the combustion rate and further engine thermal efficiency are investigated under decoupled condition.The results mainly show that the jet flame develops along the pre-chamber orifice centerline at the initial stage and premixed combustion play an important role,while after that,heat release zone only exist at flame surface,and premixed flame propagation controls the combustion process.In addition,with higher swirl ratio the combustion rate increases significantly due to the wider ignition area.Mixture stratification degree plays a role in accelerating the combustion,either too high or too low stratification degree reduce the combustion rate,while a moderate stratification increases the combustion rate.And appropriate stratification degree by verifying the gas injection parameters can reduce fuel consumption in 0.3%.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.91941102 and 51922076).
文摘High-pressure direct-injection (HPDI) of natu- ral gas is one of the most promising solutions for future ship engines, in which the combustion process is mainly controlled by the chemical kinetics. However, the employment of detailed chemical models for the multi-dimensional combustion simulation is significantly expensive due to the large scale of the marine engine. In the present paper, a reduced n-heptane/methane model consisting of 35-step reactions was constructed using multiple reduction approaches. Then this model was further reduced to include only 27 reactions by utilizing the HyChem (Hybrid Chemistry) method. An overall good agreement with the experimentally measured ignition delay data of both n-heptane and methane for these two reduced models was achieved and reasonable predictions for the measured laminar flame speeds were obtained for the 35-step model. But the 27-step model cannot predict the laminar flame speed very well. In addition, these two reduced models were both able to reproduce the experimentally measured in-cylinder pressure and heat release rate profiles for a HPDI natural gas marine engine, the highest error of predicted combustion phase being 6.5%. However, the engine-out CO emission was over-predicted and the highest error of predicted NOx emission was less than 12.9%. The predicted distributions of temperature and equivalence ratio by the 35-step and 27-step models are similar to those of the 334-step model. However, the predicted distributions of OH and CH2O are significantly different from those of the 334-step model. In short, the reduced chemical kinetic models developed provide a high-efficient and dependable method to simulate the characteristics of combustion and emissions in HPDI natural gas marine engines.
文摘This paper focuses on the creation of a dynamic probabilistic model which simulates deterioration trends of a marine engine lubricationsystem. The approach is based on risk and the implementation is achieved through a dynamic Bayesian network (dBN).Risk can be useful for decision making, while dBNs are a powerful tool for risk modelling and prediction models. The model takesinto account deterioration of engine components, oil degradation and the off-line condition monitoring technique of oil analysis, inthe context of predictive maintenance. The paper aims to efficiently predict probability evolution for main engine lubrication failureand to decide upon the most beneficial schemes from a variety of lubrication oil analysis interval schemes by introducing monetarycosts and producing the risk model. Real data and respective analysis, along with expert elicitation, are utilized for achieving modelquantification, while themodel is materialized through a code in the Matlab environment. Results from the probabilistic model showa realistic simulation for the system and indicate the obvious, that with more frequent oil analyses and respective maintenance orrepairs, the probability of failure drops significantly. However, the results from the risk model highlight that the costs can redefinescheme suggestions, as they can correspond to low probabilities of failure but also to higher costs. A two-month interval scheme issuggested, in contrast to the most preferred practice among shipping companies of a three-month interval. The developed model isin general identified as a failure prediction tool focusing on marine engine lubrication failure.
文摘Human error,an important factor,may lead to serious results in various operational fields.The human factor plays a critical role in the risks and hazards of the maritime industry.A ship can achieve safe navigation when all operations in the engine room are conducted vigilantly.This paper presents a systematic evaluation of 20 failures in auxiliary systems of marine diesel engines that may be caused by human error.The Cognitive Reliability Error Analysis Method(CREAM)is used to determine the potentiality of human errors in the failures implied thanks to the answers of experts.Using this method,the probabilities of human error on failures were evaluated and the critical ones were emphasized.The measures to be taken for these results will make significant contributions not only to the seafarers but also to the ship owners.
文摘In the organizational context of marine engineering,employee individual often prefers to concentrate herself to the day-to-day routine job,but to shirk the responsibilities of the Information Security Policies(ISPs)compliance,after she has been delegated by the employer to perform the two different tasks in the same time period.This would lead to negative influences on the security of marine information systems and the employee’s routine job performance.In view of the task structures of employee’s routine job and marine ISPs compliance,the variables of emphasis on scheduling are incorporated into a multi-task principal-agent model to explore the optimal incentive scheme to motivate and control the employees to select appropriate effort levels for conducting the two highly structured tasks.The role of emphasis on scheduling on the incentive intensities for the two tasks have been clarified through modeling and simulation,and the corresponding incentive tactics are suggested.The new two-task incentive scheme is expected to provide useful insight for understanding and controlling marine engineering employee’s routine job and ISPs compliance behavior.
文摘This paper presents a simulator model of a marine diesel engine based on physical, semi-physical, mathematical and thermodynamic equations, which allows fast predictive simulations The whole engine system is divided into several functional blocks： cooling, lubrication, air, injection, combustion and emissions. The sub-models and dynamic characteristics of individual blocks are established according to engine working principles equations and experimental data collected from a marine diesel engine test bench for SIMB Company under the reference 6M26SRP1. The overall engine system dynamics is expressed as a set of simultaneous algebraic and differential equations using sub-blocks and S-Functions of Matlab/Simulink. The simulation of this model, implemented on Matlab/Simulink has been validated and can be used to obtain engine performance, pressure, temperature, efficiency, heat release, crank angle, fuel rate, emissions at different sub-blocks. The simulator will be used, in future work, to study the engine performance in faulty conditions, and can be used to assist marine engineers in fault diagnosis and estimation （FDI） as well as designers to predict the behavior of the cooling system, lubrication system, injection system, combustion, emissions, in order to optimize the dimensions of different components. This program is a platform for fault simulator, to investigate the impact on sub-blocks engine＇s output of changing values for faults parameters such as： faulty fuel injector, leaky cylinder, worn fuel pump, broken piston rings, a dirty turbocharger, dirty air filter, dirty air cooler, air leakage, water leakage, oil leakage and contamination, fouling of heat exchanger, pumps wear, failure of injectors （and many others）.
