The nonlinear biased ship rolling motion and capsizing in randoro waves are studied by utilizing a global geometric method. Thompson＇ s α-parameterized family of restoring functions is adopted in the vessel equation...The nonlinear biased ship rolling motion and capsizing in randoro waves are studied by utilizing a global geometric method. Thompson＇ s α-parameterized family of restoring functions is adopted in the vessel equation of motion for the representation of bias. To take into account the presence of randomness in the excitation and the response, a stochastic Melnikov method is developed and a mean-square criterion is obtained to provide an upper bound on the domain of the potential chaotic rolling motion. This criterion can be used to predict the qualitative nature of the invariant manifolds which represent the boundary botween safe and unsafe initial conditions, and how these depend on system parameters of the specific ship model. Phase space transport theory and lobe dynamics are used to demonstrate how motions starting from initial conditions inside the regions bounded by the intersected manifolds will evolve and how unexpected capsizing can occur.展开更多
Brown carbon(BrC)is one of the important light absorption substances that have high light absorption ability under short wavelength light.However,limit studies have focused on the BrC emission from ships.In this study...Brown carbon(BrC)is one of the important light absorption substances that have high light absorption ability under short wavelength light.However,limit studies have focused on the BrC emission from ships.In this study,size-segregated particulate matters(PM)were collected from three different types of ships,light absorption characteristics and size distribution of methanol-soluble BrC and water-soluble BrC in PM from ship exhausts were investigated.Results showed that four-stroke low-power diesel fishing boat(4-LDF)had the highest mass concentrations of methanol-soluble organic carbon(MSOC)and water-soluble organic carbon(WSOC),followed by 2-stroke high-power heavy-fuel-oil vessel(2-HHV),and fourstroke high-power marine-diesel vessel(4-HMV).While 2-HHV had obviously higher light absorption coefficients of methanol-soluble BrC(Abs365,M)and water-soluble BrC(Abs365,W)in unit weight of PM than the other two types of ships.The tested ships presented comparable or higher absorption efficiency of BrC in water extracts(MAE365,W)compared with other BrC emission sources.Majority of BrC was concentrated in fine particles,and the particle size distributions of both Abs365,Mand Abs365,Wshowed bimodal patterns,peaking at0.43–0.65μm and 4.7–5.8μm,respectively.However,different particle size distributions were found for MAE365,Mbetween diesel and heavy fuel oil ships.Besides,different wavelength dependence in particles with different size were also detected.Ship exhaust could be confirmed as a non-ignorable BrC emission source,and complex influencing factor could affect the light absorption characteristics of ship emissions.Particle size should also be considered when light absorption ability of BrC was evaluated.展开更多
C801 missile weapon system fired from a surface ship or an aircraft is chiefly used to attack surface ships of medium size,such as frigates and destroyers.This paper describes the weapon system in detail and analyses ...C801 missile weapon system fired from a surface ship or an aircraft is chiefly used to attack surface ships of medium size,such as frigates and destroyers.This paper describes the weapon system in detail and analyses its performance.展开更多
文摘The nonlinear biased ship rolling motion and capsizing in randoro waves are studied by utilizing a global geometric method. Thompson＇ s α-parameterized family of restoring functions is adopted in the vessel equation of motion for the representation of bias. To take into account the presence of randomness in the excitation and the response, a stochastic Melnikov method is developed and a mean-square criterion is obtained to provide an upper bound on the domain of the potential chaotic rolling motion. This criterion can be used to predict the qualitative nature of the invariant manifolds which represent the boundary botween safe and unsafe initial conditions, and how these depend on system parameters of the specific ship model. Phase space transport theory and lobe dynamics are used to demonstrate how motions starting from initial conditions inside the regions bounded by the intersected manifolds will evolve and how unexpected capsizing can occur.
基金supported by the National Natural Science Foundation of China(Nos.42130704,42077195)the State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex(No.2021080547)the Ministry of Industry and Information Technology of China(No.MC-202019-C08)。
文摘Brown carbon(BrC)is one of the important light absorption substances that have high light absorption ability under short wavelength light.However,limit studies have focused on the BrC emission from ships.In this study,size-segregated particulate matters(PM)were collected from three different types of ships,light absorption characteristics and size distribution of methanol-soluble BrC and water-soluble BrC in PM from ship exhausts were investigated.Results showed that four-stroke low-power diesel fishing boat(4-LDF)had the highest mass concentrations of methanol-soluble organic carbon(MSOC)and water-soluble organic carbon(WSOC),followed by 2-stroke high-power heavy-fuel-oil vessel(2-HHV),and fourstroke high-power marine-diesel vessel(4-HMV).While 2-HHV had obviously higher light absorption coefficients of methanol-soluble BrC(Abs365,M)and water-soluble BrC(Abs365,W)in unit weight of PM than the other two types of ships.The tested ships presented comparable or higher absorption efficiency of BrC in water extracts(MAE365,W)compared with other BrC emission sources.Majority of BrC was concentrated in fine particles,and the particle size distributions of both Abs365,Mand Abs365,Wshowed bimodal patterns,peaking at0.43–0.65μm and 4.7–5.8μm,respectively.However,different particle size distributions were found for MAE365,Mbetween diesel and heavy fuel oil ships.Besides,different wavelength dependence in particles with different size were also detected.Ship exhaust could be confirmed as a non-ignorable BrC emission source,and complex influencing factor could affect the light absorption characteristics of ship emissions.Particle size should also be considered when light absorption ability of BrC was evaluated.
文摘C801 missile weapon system fired from a surface ship or an aircraft is chiefly used to attack surface ships of medium size,such as frigates and destroyers.This paper describes the weapon system in detail and analyses its performance.
