An experiment was conducted to find the variability of driver eye movement according to different driving experience. An eye tracking system was used to study the regularity of driver eye movements, such as fixation d...An experiment was conducted to find the variability of driver eye movement according to different driving experience. An eye tracking system was used to study the regularity of driver eye movements, such as fixation duration, variations of fixation points, and the distribution of glance zone. It was found that driving experience had a significant effect on driver eye movement behavior. The percentage of fixation duration to total glance time for inexperienced drivers was 61.5%, while the percentage for experienced drivers was 50.2%. Moreover, the majority of drivers paid attention to the left region of the field of view more frequently than the central and the right regions. This study indicates that it takes inexperienced drivers more time to recognize traffic signs. The findings from this study will assist traffic engineers in designing and installing the traffic signs in an optimal way.展开更多
Taking CL-20(Hexanitrohexaazaisowurtzitane)-based aluminized explosives with high gurney energy as the research object, this research experimentally investigates the work capability of different aluminized explosive f...Taking CL-20(Hexanitrohexaazaisowurtzitane)-based aluminized explosives with high gurney energy as the research object, this research experimentally investigates the work capability of different aluminized explosive formulations when driving metal flyer plates in the denotation wave propagation direction.The research results showed that the formulations with 43 μm aluminum(Al) powder particles(The particle sizes of Al powder were in the range of 2~43 μm) exhibited the optimal performance in driving flyer plates along the denotation wave propagation direction. Compared to the formulations with Al powder 13 μm, the formulations with Al powder 2 μm delivered better performance in accelerating metal flyer plates in the early stage, which, however, turned to be poor in the later stage. The CL-20-based explosives containing 25% Al far under-performed those containing 15% Al. Based on the proposed quasi-isentropic hypothesis, relevant isentropy theories, and the functional relationship between detonation parameters and entropy as well as Al reaction degree, the characteristic lines of aluminized explosives in accelerating flyer plates were theoretically studied, a quasi-isentropic theoretical model for the aluminized explosive driving the flyer plate was built and the calculation methods for the variations of flyer plate velocity, Al reaction degree, and detonation product parameters with time and axial positions were developed. The theoretical model built is verified by the experimental results of the CL-20-based aluminized explosive driving flyer plate. It was found that the model built could accurately calculate the variations of flyer plate velocity and Al reaction degree over time. In addition, how physical parameters including detonation product pressure and temperature varied with time and axial positions was identified. The action time of the positive pressure after the detonation of aluminized explosives was found prolonged and the downtrend of the temperature was slowed down and even reversed to a slight rise due to the aftereffect reaction between the Al powder and the detonation products.展开更多
The design principle and the structural characters of a new sine driving system apparatus, which have been used by NPU NF-3 wind tunnel in the dynamic stall experiments on the oscillating aerofoil model from 1994, is ...The design principle and the structural characters of a new sine driving system apparatus, which have been used by NPU NF-3 wind tunnel in the dynamic stall experiments on the oscillating aerofoil model from 1994, is introduced. Some measures to improve the stability and flexibility are studied. The obvious advantages of the system are its simple structure, convenient operation and more accurate sine relationship between the attack angle and the rotating angle of the aerofoil The driving system has been proved advisable comparing with the experimental results both abroad and in many dynamic tests in NF-3 wind tunnel. It can provide guidelines for the study of the aerodynamic properties on the oscillating aerofoil.展开更多
The Philippines is expecting a rise in the number of drivers that use mobile phones while driving.It is known as the“texting capital of the world”.The objectives of this study were to determine the predictors,risk p...The Philippines is expecting a rise in the number of drivers that use mobile phones while driving.It is known as the“texting capital of the world”.The objectives of this study were to determine the predictors,risk perceptions and the prevalence of cell phone use while driving among trainee residents of the University of the Philippines-Philippine General Hospital.This cross-sectional study employed total enumeration.A survey was first distributed to the target population,followed by a focus group discussion.Chi-square and multiple logistic regression were used to analyze data.Included in the final analysis were 175 drivers aged 25-30 years(mean=27.90+1.34).There was no significant difference in the risk perceptions of cell phone users vs.non-users,and most perceived hands-free devices safer to use(p=0.030).The reported prevalence is 90.68%;drivers have a significant overall unsafe attitude(p=0.007),and an unsafe attitude when using handsets when driving,even when this is known to be dangerous(p=0.003).In conclusion,driving with hands-free devices was perceived to be safer,although drivers have a high overall unsafe attitude.Driving for more than two years and having an unsafe attitude were found to be significant predictors of cell phone use while driving.Countermeasures must take into account these factors when instituting behavioral modification strategies and road safety policies concerning unsafe and distracted driving.展开更多
文摘An experiment was conducted to find the variability of driver eye movement according to different driving experience. An eye tracking system was used to study the regularity of driver eye movements, such as fixation duration, variations of fixation points, and the distribution of glance zone. It was found that driving experience had a significant effect on driver eye movement behavior. The percentage of fixation duration to total glance time for inexperienced drivers was 61.5%, while the percentage for experienced drivers was 50.2%. Moreover, the majority of drivers paid attention to the left region of the field of view more frequently than the central and the right regions. This study indicates that it takes inexperienced drivers more time to recognize traffic signs. The findings from this study will assist traffic engineers in designing and installing the traffic signs in an optimal way.
基金National Natural Science Foundation of China(Grant No.11872120).
文摘Taking CL-20(Hexanitrohexaazaisowurtzitane)-based aluminized explosives with high gurney energy as the research object, this research experimentally investigates the work capability of different aluminized explosive formulations when driving metal flyer plates in the denotation wave propagation direction.The research results showed that the formulations with 43 μm aluminum(Al) powder particles(The particle sizes of Al powder were in the range of 2~43 μm) exhibited the optimal performance in driving flyer plates along the denotation wave propagation direction. Compared to the formulations with Al powder 13 μm, the formulations with Al powder 2 μm delivered better performance in accelerating metal flyer plates in the early stage, which, however, turned to be poor in the later stage. The CL-20-based explosives containing 25% Al far under-performed those containing 15% Al. Based on the proposed quasi-isentropic hypothesis, relevant isentropy theories, and the functional relationship between detonation parameters and entropy as well as Al reaction degree, the characteristic lines of aluminized explosives in accelerating flyer plates were theoretically studied, a quasi-isentropic theoretical model for the aluminized explosive driving the flyer plate was built and the calculation methods for the variations of flyer plate velocity, Al reaction degree, and detonation product parameters with time and axial positions were developed. The theoretical model built is verified by the experimental results of the CL-20-based aluminized explosive driving flyer plate. It was found that the model built could accurately calculate the variations of flyer plate velocity and Al reaction degree over time. In addition, how physical parameters including detonation product pressure and temperature varied with time and axial positions was identified. The action time of the positive pressure after the detonation of aluminized explosives was found prolonged and the downtrend of the temperature was slowed down and even reversed to a slight rise due to the aftereffect reaction between the Al powder and the detonation products.
文摘The design principle and the structural characters of a new sine driving system apparatus, which have been used by NPU NF-3 wind tunnel in the dynamic stall experiments on the oscillating aerofoil model from 1994, is introduced. Some measures to improve the stability and flexibility are studied. The obvious advantages of the system are its simple structure, convenient operation and more accurate sine relationship between the attack angle and the rotating angle of the aerofoil The driving system has been proved advisable comparing with the experimental results both abroad and in many dynamic tests in NF-3 wind tunnel. It can provide guidelines for the study of the aerodynamic properties on the oscillating aerofoil.
文摘The Philippines is expecting a rise in the number of drivers that use mobile phones while driving.It is known as the“texting capital of the world”.The objectives of this study were to determine the predictors,risk perceptions and the prevalence of cell phone use while driving among trainee residents of the University of the Philippines-Philippine General Hospital.This cross-sectional study employed total enumeration.A survey was first distributed to the target population,followed by a focus group discussion.Chi-square and multiple logistic regression were used to analyze data.Included in the final analysis were 175 drivers aged 25-30 years(mean=27.90+1.34).There was no significant difference in the risk perceptions of cell phone users vs.non-users,and most perceived hands-free devices safer to use(p=0.030).The reported prevalence is 90.68%;drivers have a significant overall unsafe attitude(p=0.007),and an unsafe attitude when using handsets when driving,even when this is known to be dangerous(p=0.003).In conclusion,driving with hands-free devices was perceived to be safer,although drivers have a high overall unsafe attitude.Driving for more than two years and having an unsafe attitude were found to be significant predictors of cell phone use while driving.Countermeasures must take into account these factors when instituting behavioral modification strategies and road safety policies concerning unsafe and distracted driving.
