In 2024,global shipments of new short-staple spindles and open-end rotors decreased by 40%and 39%,respectively(year-on-year).Deliveries of long-staple spindles increased by 62%.The number of draw texturing spindles im...In 2024,global shipments of new short-staple spindles and open-end rotors decreased by 40%and 39%,respectively(year-on-year).Deliveries of long-staple spindles increased by 62%.The number of draw texturing spindles improved by 77%and shipped shuttleless looms grew by 32%.Shipments of large circular knitting machines deteriorated by 15%and shipped flat knitting machines registered a 16%increase.The sum of all deliveries in the fin-ishing segment slightlyrose by 6%.展开更多
The accelerated decline of Arctic sea ice since the 1980s has paradoxically amplified greenhouse gas(GHG)emissions through increased shipping activities in this ecologically vulnerable region.This study investigates h...The accelerated decline of Arctic sea ice since the 1980s has paradoxically amplified greenhouse gas(GHG)emissions through increased shipping activities in this ecologically vulnerable region.This study investigates how to reconcile the decarbonization of Arctic shipping with conflicting environmental,economic,and geopolitical interests.Through systematic literature review and interest-balancing analysis,our findings identify three systemic barriers:(1)inadequate adaptation of International Maritime Organization(IMO)regulations to Arctic-specific environmental risks,(2)fragmented enforcement mechanisms among Arctic and non-Arctic States,and(3)technological limitations in clean fuel adoption for ice-class vessels.To address these challenges,a tripartite governance framework is proposed.First,legally binding amendments to International Convention for the Prevention of Pollution from Ships(MARPOL)Annex VI introducing Arctic-specific Energy Efficiency eXisting ship Index(EEXI)standards and extending energy efficiency regulations to fishing vessels.Second,a phased fuel transition prioritizing liquefied natural gas(LNG)and methanol,followed by hydrogen-ammonia synthetics.Third,enhanced multilateral cooperation through an Arctic Climate Shipping Alliance to coordinate joint research and development in cold-adapted technologies and ice-route optimization.By integrating United Nations Convention on the Law of the Sea(UNCLOS)obligations with IMO Polar Code implementation,this study advances a dynamic interest-balancing framework for policymakers,offering actionable pathways to achieve Paris Agreement targets while safeguarding Arctic ecosystems.展开更多
Ship outfitting is a key process in shipbuilding.Efficient and high-quality ship outfitting is a top priority for modern shipyards.These activities are conducted at different stations of shipyards.The outfitting plan ...Ship outfitting is a key process in shipbuilding.Efficient and high-quality ship outfitting is a top priority for modern shipyards.These activities are conducted at different stations of shipyards.The outfitting plan is one of the crucial issues in shipbuilding.In this paper,production scheduling and material ordering with endogenous uncertainty of the outfitting process are investigated.The uncertain factors in outfitting equipment production are usually decision-related,which leads to difficulties in addressing uncertainties in the outfitting production workshops before production is conducted according to plan.This uncertainty is regarded as endogenous uncertainty and can be treated as non-anticipativity constraints in the model.To address this problem,a stochastic two-stage programming model with endogenous uncertainty is established to optimize the outfitting job scheduling and raw material ordering process.A practical case of the shipyard of China Merchants Heavy Industry Co.,Ltd.is used to evaluate the performance of the proposed method.Satisfactory results are achieved at the lowest expected total cost as the complete kit rate of outfitting equipment is improved and emergency replenishment is reduced.展开更多
To study the rolling motion of a ship in the presence of water on its deck,a linear-plus-quadratic damping term was incorporated into its equation of motion.Ship model tests indicates that the key dynamics of the phys...To study the rolling motion of a ship in the presence of water on its deck,a linear-plus-quadratic damping term was incorporated into its equation of motion.Ship model tests indicates that the key dynamics of the physical system are preserved in the ship rolling equation with the linear-plus-quadratic type damping term.To take into account the presence of randomness in the excitation and the response,a new method was developed and a Melnikov criterion was obtained to provide an upper bound on the domain of the potential chaotic rolling motion(erratic rocking).Additionally,the Melnikov criterion proposed in this study was verified by the utilization of phase plane diagrams and Poincare maps.Furthermore,this research has made the initial endeavor to systematically modify the system parameters in the rolling equation of motion for ship stability analysis.展开更多
Ice-going ships play a crucial role in polar transportation and resource extraction.Different from the existing modeling approach which assumes that ships remain stationary,dynamic overset grid technology and DFBI(Dyn...Ice-going ships play a crucial role in polar transportation and resource extraction.Different from the existing modeling approach which assumes that ships remain stationary,dynamic overset grid technology and DFBI(Dynamic Fluid-Body Interaction)method are employed in this paper to enable the free-running motion of the ship in modeling.A numerical model capable of simulating a ship navigating through pack ice area is proposed,which uses Computational Fluid Dynamics(CFD)method to solve the flow field and applies the Discrete Element Method(DEM)to simulate ship-ice and ice-ice interactions.Besides,the proposed high-precision method for generating pack ice area can be used in conjunction with the proposed numerical model.By comparing the numerical results with the available model test data and experimental observations,the effectiveness of the numerical model is validated,demonstrating its strong capability of predicting resistance and simulating ship navigation in pack ice,as well as its significant potential and applicability for further studies.展开更多
In order to accurately forecast the main engine fuel consumption and reduce the Energy Efficiency Operational Indicator(EEOI)of merchant ships in polar ice areas,the energy transfer relationship between ship-machine-p...In order to accurately forecast the main engine fuel consumption and reduce the Energy Efficiency Operational Indicator(EEOI)of merchant ships in polar ice areas,the energy transfer relationship between ship-machine-propeller is studied by analyzing the complex force situation during ship navigation and building a MATLAB/Simulink simulation platform based on multi-environmental resistance,propeller efficiency,main engine power,fuel consumption,fuel consumption rate and EEOI calculation module.Considering the environmental factors of wind,wave and ice,the route is divided into sections,the calculation of main engine power,main engine fuel consumption and EEOI for each section is completed,and the speed design is optimized based on the simulation model for each section.Under the requirements of the voyage plan,the optimization results show that the energy efficiency operation index of the whole route is reduced by 3.114%and the fuel consumption is reduced by 9.17 t.展开更多
World’s First Ammonia-Fueled Vessel Sets Sail The world's first pure ammonia-powered demonstration vessel,the Anhui,successfully completed its maiden voyage in Hefei,east China's Anhui Province,on June 28,mar...World’s First Ammonia-Fueled Vessel Sets Sail The world's first pure ammonia-powered demonstration vessel,the Anhui,successfully completed its maiden voyage in Hefei,east China's Anhui Province,on June 28,marking a major step forward for green shipping.Ammonia,a major chemical industry feedstock,has a high energy density and due to its carbon-free nature,produces only water and nitrogen when fully combusted.This makes it a highly promising fuel for decarbonizing shipping.展开更多
The Titanic sunk 113 years ago on April 14-15,after hitting an iceberg,with human error likely causing the ship to wander into those dangerous waters.Today,autonomous systems built on AI can help ships avoid such acci...The Titanic sunk 113 years ago on April 14-15,after hitting an iceberg,with human error likely causing the ship to wander into those dangerous waters.Today,autonomous systems built on AI can help ships avoid such accidents.But could such a system explain to the captain why it was controlling the ship in a certain way?展开更多
Semisubmersible naval ships are versatile military crafts that combine the advantageous features of high-speed planing crafts and submarines.At-surface,these ships are designed to provide sufficient speed and maneuver...Semisubmersible naval ships are versatile military crafts that combine the advantageous features of high-speed planing crafts and submarines.At-surface,these ships are designed to provide sufficient speed and maneuverability.Additionally,they can perform shallow dives,offering low visual and acoustic detectability.Therefore,the hydrodynamic design of a semisubmersible naval ship should address at-surface and submerged conditions.In this study,Numerical analyses were performed using a semisubmersible hull form to analyze its hydrodynamic features,including resistance,powering,and maneuvering.The simulations were conducted with Star CCM+version 2302,a commercial package program that solves URANS equations using the SST k-ωturbulence model.The flow analysis was divided into two parts:at-surface simulations and shallowly submerged simulations.At-surface simulations cover the resistance,powering,trim,and sinkage at transition and planing regimes,with corresponding Froude numbers ranging from 0.42 to 1.69.Shallowly submerged simulations were performed at seven different submergence depths,ranging from D/LOA=0.0635 to D/LOA=0.635,and at two different speeds with Froude numbers of 0.21 and 0.33.The behaviors of the hydrodynamic forces and pitching moment for different operation depths were comprehensively analyzed.The results of the numerical analyses provide valuable insights into the hydrodynamic performance of semisubmersible naval ships,highlighting the critical factors influencing their resistance,powering,and maneuvering capabilities in both at-surface and submerged conditions.展开更多
Ship emissions contribute considerably to air pollution and are expected to decline under domestic policies and international cooperation such as green shipping corridors(GSCs).However,evaluation of the emission reduc...Ship emissions contribute considerably to air pollution and are expected to decline under domestic policies and international cooperation such as green shipping corridors(GSCs).However,evaluation of the emission reduction potential by the Domestic Emission Control Area(DECA)policy and GSC cooperation is still lacking.Here,a series of multi-year high spatiotemporal ship emission inventories around Hainan,a representative island province of China,were developed with the state-of-the-art Shipping Emission Inventory Model.The improved origin-destination identification algorithm allowed emission allocation to port level.The emission reduction potential of the DECA policy and Hainan's joining GSCwas analyzed.In 2022,ship emission intensity in waters 12 Nm from Hainan(Hainan-12Nm)were 6.4%-7.4% of that in waters 12 Nm from China.From 2019 to 2022,Hainan-12Nm emissions dropped by 66.7%-77.8% for SO_(2) and PM2.5.Ideally,with adequate ultra-low-sulfur fuel,DECA can reduce SO_(2) and PM2.5 emissions by 16.6% and 22.4% yearly compared with no-DECA scenario.However,emission reduction would drop markedly if ultra-low-sulfur fuel is short in supply.Emissions of voyages passing through 200 Nm from Hainan took up 1%-4%of international shipping emissions,implying great emission reduction potential for Hainan's establishing GSCs,especially considering the flourishing South-South trade.This study provides a thorough assessment of the current state of shipping emissions around Hainan as well as offers excellent data support for Hainan to further advance the future upgrade of ship emission management policies.展开更多
Ships experience rolling motion under the action of sea waves and may even face the risk of capsizing.Anti-rolling devices are designed to reduce this motion and enhance vessel safety.This is especially critical for e...Ships experience rolling motion under the action of sea waves and may even face the risk of capsizing.Anti-rolling devices are designed to reduce this motion and enhance vessel safety.This is especially critical for engineering ships operating at sea under zero-speed conditions,where a stable posture is essential for efficient performance.Gyro stabilizers can suppress roll motion at zero speed;however,their high cost typically makes them unsuitable for large civilian vessels.Additionally,most existing anti-rolling devices rely on a certain water speed to function,which results in increased drag.In this study,an anti-rolling system incorporating swing control is proposed.Inspired by the human body's ability to maintain balance by swinging arms during walking or running,the system generates an antirolling moment by oscillating a water tank.This approach operates independently of water speed and does not generate additional drag.The mechanical design of the anti-rolling system is introduced,and a corresponding control system model is derived.The swing-tank mechanism provides phase lead compensation and reduces the system's sensitivity to wave disturbances.To enhance performance,robust control techniques are applied.Simulation results demonstrate that the proposed anti-rolling system delivers effective roll reduction for ships.展开更多
In observation of efficiently utilizing the boil off gas(BOG)from onboard liquefied natural gas(LNG),storage by adsorption is employed to construct an auxiliary system for fuel storage.A typical LNG powered ship was s...In observation of efficiently utilizing the boil off gas(BOG)from onboard liquefied natural gas(LNG),storage by adsorption is employed to construct an auxiliary system for fuel storage.A typical LNG powered ship was selected,and the storage by adsorption system was designed as per the amount of BOG released during the process of charging and that from daily evaporation on the LNG storage tank.Researches were conducted experimentally and numerically on a 1 L conformable vessel typically designed for adsorbing BOG.Verification of the accuracy of the results from simulations was performed by comparing the data recorded during the charging and discharging process of methane on the vessel packed with one kind of commercially available activated carbon SAC-01(S_(BET)=1507 m^(2)·g^(-1)).Simulations were conducted further to evaluate the performance of the vessel respectively filled with activated carbon AX-21,HKUST-1,MIL-101(Cr),MOF-5.It shows that the mean relative error between the data from simulations and the experimental data is less than 5%.Results also reveal that,within the flow rates range in correspondence with the fuel consumed by the model ship's power unit under its typical working conditions,the mean temperature fluctuation within the vessel is the weakest while packing HKUST-1,which results in the largest accumulated amount of discharge.It suggests that HKUST-1 is a suitable adsorbent for storage by adsorption of BOG from on board LNG.展开更多
Global warming has made the regular operation of Arctic routes possible.This study selects hub ports based on infrastructure conditions and sea ice status,and then designs two pendulum route solutions for the Northeas...Global warming has made the regular operation of Arctic routes possible.This study selects hub ports based on infrastructure conditions and sea ice status,and then designs two pendulum route solutions for the Northeast Passage according to the distance between hub ports and ice-covered areas.We employ an evaluation framework combining annual profit metrics with discounted net present value(NPV)analysis,conducting probabilistic economic assessments through Monte Carlo simulations(20,000 iterations).Key findings indicate that(1)both solutions demonstrate>90%probability of economic viability and(2)Solution I′,with hub ports closer to ice-covered areas than those in Solution II,yields 5.02%higher mean annual profit and 4.69%greater NPV.The results indicate that pendulum routes in the Northeast Passage can achieve economic benefits by enabling year-round regular operations.Moreover,shorter shipping distances between hub ports and ice-covered areas enhance economic viability.展开更多
I.Look and say something about the pictures.Li Li:What's this in English,Jerry?Jerry:It is a boat.Li Li:Is that a boat in English,Jerry?Jerry:No,it isn't.It is a ship in English.L Li Li:I see.Thank you.Jerry:Y...I.Look and say something about the pictures.Li Li:What's this in English,Jerry?Jerry:It is a boat.Li Li:Is that a boat in English,Jerry?Jerry:No,it isn't.It is a ship in English.L Li Li:I see.Thank you.Jerry:You're welcome.展开更多
Recently,ship detection technology has been applied extensively in the marine security monitoring field.However,achieving accurate marine ship detection still poses significant challenges due to factors such as varyin...Recently,ship detection technology has been applied extensively in the marine security monitoring field.However,achieving accurate marine ship detection still poses significant challenges due to factors such as varying scales,slightly occluded objects,uneven illumination,and sea clutter.To address these issues,we propose a novel ship detection approach,i.e.,the Twin Feature Pyramid Network and Data Augmentation(TFPN-DA),which mainly consists of three modules.First,to eliminate the negative effects of slightly occluded objects and uneven illumination,we propose the Spatial Attention within the Twin Feature Pyramid Network(SA-TFPN)method,which is based on spatial attention to reconstruct the feature pyramid.Second,the ROI Feature Module(ROIFM)is introduced into the SA-TFPN,which is used to enhance specific crucial details from multi-scale features for object regression and classification.Additionally,data augmentation strategies such as spatial affine transformation and noise processing,are developed to optimize the data sample distribution.A self-construct dataset is used to train the detection model,and the experiments conducted on the dataset demonstrate the effectiveness of our model.展开更多
The population growth in Ghana has assumed an alarming rate.The provision of urban infrastructure and housing has however not been commensurate with the demand especially in housing,thus the acute housing deficit.The ...The population growth in Ghana has assumed an alarming rate.The provision of urban infrastructure and housing has however not been commensurate with the demand especially in housing,thus the acute housing deficit.The idea of using shipping containers as a building component is by no means new in the Accra Metropolis as most shipping containers are re-constructed architecturally and used for temporary accommodation needs like storage,make-shift shops,emergency shelters and site offices.The concept of using these shipping containers as modular building components in architecture however,is still foreign to building practitioners and the nation at large.This research paper set out to use the containers not for luxury apartments but to harness the merits of availability,low-cost of resource,speed of construction and structural stability of the International Standard Organization(ISO)shipping containers in addressing the housing deficiency problem in the nation by meeting the basic need of shelter.Based on the hypothesis of being a cheaper alternative to the concrete and sand-crete blocks,which is the main construction technology used now,similar house types of both technologies were compared to ascertain the variation as part of the methodology for this research.The methodology also included literature reviews and case studies.The scope of this study was limited to 2-bedroom single-storey and multi-storey house types in Accra,the capital city of Ghana.In the final analysis however,this research proved that the container house is not cheaper than the traditional blockwork and concrete construction method is and is better used in temporary accommodation,in situations where time is essential.展开更多
Polar marine equipment plays an important role in Arctic engineering,especially in the development of polar ships and ice-class propellers.When polar ships navigate in brash ice channels,the brash ice not only increas...Polar marine equipment plays an important role in Arctic engineering,especially in the development of polar ships and ice-class propellers.When polar ships navigate in brash ice channels,the brash ice not only increases resistance but also has adverse effects on their propulsion performance.On the basis of coupled computational fluid dynamics(CFD)and the discrete element method(DEM),this paper aims to numerically investigate the resistance and propulsion performance of a polar in a brash ice channel while considering the rotation status of the propeller by both experimental and numerical methods.Both ship resistance and ice motion under Froude numbers of 0.0557,0.0696,0.0836,0.975,and 0.1114 are studied when the propeller does not rotate.The influences of the rotating propeller on the ice brash resistance and flow are discussed.The thrust due to the propeller and ice resistance in the equilibrium state are also predicted.The errors between the thrust and total resistance are approximately 1.0%,and the maximum error between the simulated and predicted total resistance is 3.7%,which validates the CFD-DEM coupling method quite well.This work could provide a theoretical basis for the initial design of polar ships with low ice class notation and assist in planning navigation for merchant polar ships in brash ice fields.展开更多
Tour Overview.“Yangtze River Fantasy Tour-Charm of the Yangtze”is a carefully crafted 6-night,7-day journey for you to fully experience the endless charm of China's Yangtze River.On this trip,tourists will embar...Tour Overview.“Yangtze River Fantasy Tour-Charm of the Yangtze”is a carefully crafted 6-night,7-day journey for you to fully experience the endless charm of China's Yangtze River.On this trip,tourists will embark on a top luxury cruise ship on China,s inland rivers,sailing through the Yangtze River,enjoying comfort and luxury.The modern design and complete facilities of the cruise ship not only provide first-class accommodation but also offer a variety of onboard entertainment activities,filling your journey with laughter and joy.展开更多
文摘In 2024,global shipments of new short-staple spindles and open-end rotors decreased by 40%and 39%,respectively(year-on-year).Deliveries of long-staple spindles increased by 62%.The number of draw texturing spindles improved by 77%and shipped shuttleless looms grew by 32%.Shipments of large circular knitting machines deteriorated by 15%and shipped flat knitting machines registered a 16%increase.The sum of all deliveries in the fin-ishing segment slightlyrose by 6%.
基金supported by the Major Research Projects of the National Social Science Fund of China(NSFC,Grant no.23VHQ015).
文摘The accelerated decline of Arctic sea ice since the 1980s has paradoxically amplified greenhouse gas(GHG)emissions through increased shipping activities in this ecologically vulnerable region.This study investigates how to reconcile the decarbonization of Arctic shipping with conflicting environmental,economic,and geopolitical interests.Through systematic literature review and interest-balancing analysis,our findings identify three systemic barriers:(1)inadequate adaptation of International Maritime Organization(IMO)regulations to Arctic-specific environmental risks,(2)fragmented enforcement mechanisms among Arctic and non-Arctic States,and(3)technological limitations in clean fuel adoption for ice-class vessels.To address these challenges,a tripartite governance framework is proposed.First,legally binding amendments to International Convention for the Prevention of Pollution from Ships(MARPOL)Annex VI introducing Arctic-specific Energy Efficiency eXisting ship Index(EEXI)standards and extending energy efficiency regulations to fishing vessels.Second,a phased fuel transition prioritizing liquefied natural gas(LNG)and methanol,followed by hydrogen-ammonia synthetics.Third,enhanced multilateral cooperation through an Arctic Climate Shipping Alliance to coordinate joint research and development in cold-adapted technologies and ice-route optimization.By integrating United Nations Convention on the Law of the Sea(UNCLOS)obligations with IMO Polar Code implementation,this study advances a dynamic interest-balancing framework for policymakers,offering actionable pathways to achieve Paris Agreement targets while safeguarding Arctic ecosystems.
基金supported in part by the High-tech ship scientific research project of the Ministry of Industry and Information Technology of the People’s Republic of China,and the National Nature Science Foundation of China(Grant No.71671113)the Science and Technology Department of Shaanxi Province(No.2020GY-219)the Ministry of Education Collaborative Project of Production,Learning and Research(No.201901024016).
文摘Ship outfitting is a key process in shipbuilding.Efficient and high-quality ship outfitting is a top priority for modern shipyards.These activities are conducted at different stations of shipyards.The outfitting plan is one of the crucial issues in shipbuilding.In this paper,production scheduling and material ordering with endogenous uncertainty of the outfitting process are investigated.The uncertain factors in outfitting equipment production are usually decision-related,which leads to difficulties in addressing uncertainties in the outfitting production workshops before production is conducted according to plan.This uncertainty is regarded as endogenous uncertainty and can be treated as non-anticipativity constraints in the model.To address this problem,a stochastic two-stage programming model with endogenous uncertainty is established to optimize the outfitting job scheduling and raw material ordering process.A practical case of the shipyard of China Merchants Heavy Industry Co.,Ltd.is used to evaluate the performance of the proposed method.Satisfactory results are achieved at the lowest expected total cost as the complete kit rate of outfitting equipment is improved and emergency replenishment is reduced.
文摘To study the rolling motion of a ship in the presence of water on its deck,a linear-plus-quadratic damping term was incorporated into its equation of motion.Ship model tests indicates that the key dynamics of the physical system are preserved in the ship rolling equation with the linear-plus-quadratic type damping term.To take into account the presence of randomness in the excitation and the response,a new method was developed and a Melnikov criterion was obtained to provide an upper bound on the domain of the potential chaotic rolling motion(erratic rocking).Additionally,the Melnikov criterion proposed in this study was verified by the utilization of phase plane diagrams and Poincare maps.Furthermore,this research has made the initial endeavor to systematically modify the system parameters in the rolling equation of motion for ship stability analysis.
文摘Ice-going ships play a crucial role in polar transportation and resource extraction.Different from the existing modeling approach which assumes that ships remain stationary,dynamic overset grid technology and DFBI(Dynamic Fluid-Body Interaction)method are employed in this paper to enable the free-running motion of the ship in modeling.A numerical model capable of simulating a ship navigating through pack ice area is proposed,which uses Computational Fluid Dynamics(CFD)method to solve the flow field and applies the Discrete Element Method(DEM)to simulate ship-ice and ice-ice interactions.Besides,the proposed high-precision method for generating pack ice area can be used in conjunction with the proposed numerical model.By comparing the numerical results with the available model test data and experimental observations,the effectiveness of the numerical model is validated,demonstrating its strong capability of predicting resistance and simulating ship navigation in pack ice,as well as its significant potential and applicability for further studies.
文摘In order to accurately forecast the main engine fuel consumption and reduce the Energy Efficiency Operational Indicator(EEOI)of merchant ships in polar ice areas,the energy transfer relationship between ship-machine-propeller is studied by analyzing the complex force situation during ship navigation and building a MATLAB/Simulink simulation platform based on multi-environmental resistance,propeller efficiency,main engine power,fuel consumption,fuel consumption rate and EEOI calculation module.Considering the environmental factors of wind,wave and ice,the route is divided into sections,the calculation of main engine power,main engine fuel consumption and EEOI for each section is completed,and the speed design is optimized based on the simulation model for each section.Under the requirements of the voyage plan,the optimization results show that the energy efficiency operation index of the whole route is reduced by 3.114%and the fuel consumption is reduced by 9.17 t.
文摘World’s First Ammonia-Fueled Vessel Sets Sail The world's first pure ammonia-powered demonstration vessel,the Anhui,successfully completed its maiden voyage in Hefei,east China's Anhui Province,on June 28,marking a major step forward for green shipping.Ammonia,a major chemical industry feedstock,has a high energy density and due to its carbon-free nature,produces only water and nitrogen when fully combusted.This makes it a highly promising fuel for decarbonizing shipping.
文摘The Titanic sunk 113 years ago on April 14-15,after hitting an iceberg,with human error likely causing the ship to wander into those dangerous waters.Today,autonomous systems built on AI can help ships avoid such accidents.But could such a system explain to the captain why it was controlling the ship in a certain way?
文摘Semisubmersible naval ships are versatile military crafts that combine the advantageous features of high-speed planing crafts and submarines.At-surface,these ships are designed to provide sufficient speed and maneuverability.Additionally,they can perform shallow dives,offering low visual and acoustic detectability.Therefore,the hydrodynamic design of a semisubmersible naval ship should address at-surface and submerged conditions.In this study,Numerical analyses were performed using a semisubmersible hull form to analyze its hydrodynamic features,including resistance,powering,and maneuvering.The simulations were conducted with Star CCM+version 2302,a commercial package program that solves URANS equations using the SST k-ωturbulence model.The flow analysis was divided into two parts:at-surface simulations and shallowly submerged simulations.At-surface simulations cover the resistance,powering,trim,and sinkage at transition and planing regimes,with corresponding Froude numbers ranging from 0.42 to 1.69.Shallowly submerged simulations were performed at seven different submergence depths,ranging from D/LOA=0.0635 to D/LOA=0.635,and at two different speeds with Froude numbers of 0.21 and 0.33.The behaviors of the hydrodynamic forces and pitching moment for different operation depths were comprehensively analyzed.The results of the numerical analyses provide valuable insights into the hydrodynamic performance of semisubmersible naval ships,highlighting the critical factors influencing their resistance,powering,and maneuvering capabilities in both at-surface and submerged conditions.
基金supported by the National Natural Science Foundation of China(No.42325505)the National Key R&D Program of China(No.2022YFC3704200)the Tsinghua University Initiative Scientific Research Program.
文摘Ship emissions contribute considerably to air pollution and are expected to decline under domestic policies and international cooperation such as green shipping corridors(GSCs).However,evaluation of the emission reduction potential by the Domestic Emission Control Area(DECA)policy and GSC cooperation is still lacking.Here,a series of multi-year high spatiotemporal ship emission inventories around Hainan,a representative island province of China,were developed with the state-of-the-art Shipping Emission Inventory Model.The improved origin-destination identification algorithm allowed emission allocation to port level.The emission reduction potential of the DECA policy and Hainan's joining GSCwas analyzed.In 2022,ship emission intensity in waters 12 Nm from Hainan(Hainan-12Nm)were 6.4%-7.4% of that in waters 12 Nm from China.From 2019 to 2022,Hainan-12Nm emissions dropped by 66.7%-77.8% for SO_(2) and PM2.5.Ideally,with adequate ultra-low-sulfur fuel,DECA can reduce SO_(2) and PM2.5 emissions by 16.6% and 22.4% yearly compared with no-DECA scenario.However,emission reduction would drop markedly if ultra-low-sulfur fuel is short in supply.Emissions of voyages passing through 200 Nm from Hainan took up 1%-4%of international shipping emissions,implying great emission reduction potential for Hainan's establishing GSCs,especially considering the flourishing South-South trade.This study provides a thorough assessment of the current state of shipping emissions around Hainan as well as offers excellent data support for Hainan to further advance the future upgrade of ship emission management policies.
基金supported by the Jiangxi University of Water Resources and Electric Power Doctoral Research Initiation Fund(Grant No.2024kyqd030)。
文摘Ships experience rolling motion under the action of sea waves and may even face the risk of capsizing.Anti-rolling devices are designed to reduce this motion and enhance vessel safety.This is especially critical for engineering ships operating at sea under zero-speed conditions,where a stable posture is essential for efficient performance.Gyro stabilizers can suppress roll motion at zero speed;however,their high cost typically makes them unsuitable for large civilian vessels.Additionally,most existing anti-rolling devices rely on a certain water speed to function,which results in increased drag.In this study,an anti-rolling system incorporating swing control is proposed.Inspired by the human body's ability to maintain balance by swinging arms during walking or running,the system generates an antirolling moment by oscillating a water tank.This approach operates independently of water speed and does not generate additional drag.The mechanical design of the anti-rolling system is introduced,and a corresponding control system model is derived.The swing-tank mechanism provides phase lead compensation and reduces the system's sensitivity to wave disturbances.To enhance performance,robust control techniques are applied.Simulation results demonstrate that the proposed anti-rolling system delivers effective roll reduction for ships.
基金supported by National Natural Science Foundation of China(51979121)Natural Science Foundation of Fujian Province(2024J01713,2023J01905)+1 种基金Xiamen Municipal Bureau of Sciences&Technology(3502Z20226011)Educational scientific research project for young and middle-aged teachers in Fujian Province(JAT210300).
文摘In observation of efficiently utilizing the boil off gas(BOG)from onboard liquefied natural gas(LNG),storage by adsorption is employed to construct an auxiliary system for fuel storage.A typical LNG powered ship was selected,and the storage by adsorption system was designed as per the amount of BOG released during the process of charging and that from daily evaporation on the LNG storage tank.Researches were conducted experimentally and numerically on a 1 L conformable vessel typically designed for adsorbing BOG.Verification of the accuracy of the results from simulations was performed by comparing the data recorded during the charging and discharging process of methane on the vessel packed with one kind of commercially available activated carbon SAC-01(S_(BET)=1507 m^(2)·g^(-1)).Simulations were conducted further to evaluate the performance of the vessel respectively filled with activated carbon AX-21,HKUST-1,MIL-101(Cr),MOF-5.It shows that the mean relative error between the data from simulations and the experimental data is less than 5%.Results also reveal that,within the flow rates range in correspondence with the fuel consumed by the model ship's power unit under its typical working conditions,the mean temperature fluctuation within the vessel is the weakest while packing HKUST-1,which results in the largest accumulated amount of discharge.It suggests that HKUST-1 is a suitable adsorbent for storage by adsorption of BOG from on board LNG.
文摘Global warming has made the regular operation of Arctic routes possible.This study selects hub ports based on infrastructure conditions and sea ice status,and then designs two pendulum route solutions for the Northeast Passage according to the distance between hub ports and ice-covered areas.We employ an evaluation framework combining annual profit metrics with discounted net present value(NPV)analysis,conducting probabilistic economic assessments through Monte Carlo simulations(20,000 iterations).Key findings indicate that(1)both solutions demonstrate>90%probability of economic viability and(2)Solution I′,with hub ports closer to ice-covered areas than those in Solution II,yields 5.02%higher mean annual profit and 4.69%greater NPV.The results indicate that pendulum routes in the Northeast Passage can achieve economic benefits by enabling year-round regular operations.Moreover,shorter shipping distances between hub ports and ice-covered areas enhance economic viability.
文摘I.Look and say something about the pictures.Li Li:What's this in English,Jerry?Jerry:It is a boat.Li Li:Is that a boat in English,Jerry?Jerry:No,it isn't.It is a ship in English.L Li Li:I see.Thank you.Jerry:You're welcome.
文摘Recently,ship detection technology has been applied extensively in the marine security monitoring field.However,achieving accurate marine ship detection still poses significant challenges due to factors such as varying scales,slightly occluded objects,uneven illumination,and sea clutter.To address these issues,we propose a novel ship detection approach,i.e.,the Twin Feature Pyramid Network and Data Augmentation(TFPN-DA),which mainly consists of three modules.First,to eliminate the negative effects of slightly occluded objects and uneven illumination,we propose the Spatial Attention within the Twin Feature Pyramid Network(SA-TFPN)method,which is based on spatial attention to reconstruct the feature pyramid.Second,the ROI Feature Module(ROIFM)is introduced into the SA-TFPN,which is used to enhance specific crucial details from multi-scale features for object regression and classification.Additionally,data augmentation strategies such as spatial affine transformation and noise processing,are developed to optimize the data sample distribution.A self-construct dataset is used to train the detection model,and the experiments conducted on the dataset demonstrate the effectiveness of our model.
文摘The population growth in Ghana has assumed an alarming rate.The provision of urban infrastructure and housing has however not been commensurate with the demand especially in housing,thus the acute housing deficit.The idea of using shipping containers as a building component is by no means new in the Accra Metropolis as most shipping containers are re-constructed architecturally and used for temporary accommodation needs like storage,make-shift shops,emergency shelters and site offices.The concept of using these shipping containers as modular building components in architecture however,is still foreign to building practitioners and the nation at large.This research paper set out to use the containers not for luxury apartments but to harness the merits of availability,low-cost of resource,speed of construction and structural stability of the International Standard Organization(ISO)shipping containers in addressing the housing deficiency problem in the nation by meeting the basic need of shelter.Based on the hypothesis of being a cheaper alternative to the concrete and sand-crete blocks,which is the main construction technology used now,similar house types of both technologies were compared to ascertain the variation as part of the methodology for this research.The methodology also included literature reviews and case studies.The scope of this study was limited to 2-bedroom single-storey and multi-storey house types in Accra,the capital city of Ghana.In the final analysis however,this research proved that the container house is not cheaper than the traditional blockwork and concrete construction method is and is better used in temporary accommodation,in situations where time is essential.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0107000)the Fundamental Research Funds for the Central Universities(Grant No.HYGJXM202319).
文摘Polar marine equipment plays an important role in Arctic engineering,especially in the development of polar ships and ice-class propellers.When polar ships navigate in brash ice channels,the brash ice not only increases resistance but also has adverse effects on their propulsion performance.On the basis of coupled computational fluid dynamics(CFD)and the discrete element method(DEM),this paper aims to numerically investigate the resistance and propulsion performance of a polar in a brash ice channel while considering the rotation status of the propeller by both experimental and numerical methods.Both ship resistance and ice motion under Froude numbers of 0.0557,0.0696,0.0836,0.975,and 0.1114 are studied when the propeller does not rotate.The influences of the rotating propeller on the ice brash resistance and flow are discussed.The thrust due to the propeller and ice resistance in the equilibrium state are also predicted.The errors between the thrust and total resistance are approximately 1.0%,and the maximum error between the simulated and predicted total resistance is 3.7%,which validates the CFD-DEM coupling method quite well.This work could provide a theoretical basis for the initial design of polar ships with low ice class notation and assist in planning navigation for merchant polar ships in brash ice fields.
文摘Tour Overview.“Yangtze River Fantasy Tour-Charm of the Yangtze”is a carefully crafted 6-night,7-day journey for you to fully experience the endless charm of China's Yangtze River.On this trip,tourists will embark on a top luxury cruise ship on China,s inland rivers,sailing through the Yangtze River,enjoying comfort and luxury.The modern design and complete facilities of the cruise ship not only provide first-class accommodation but also offer a variety of onboard entertainment activities,filling your journey with laughter and joy.
