This paper presents a comparative analysis of ground vibration in three directions generated by a heavy-duty railway with various track sections.The vibration characteristics in the plane area were investigated by usi...This paper presents a comparative analysis of ground vibration in three directions generated by a heavy-duty railway with various track sections.The vibration characteristics in the plane area were investigated by using matrix test measurements.Acceleration peak attenuation was faster within 25 m from the embankment,and the high-frequency vibration attenuates faster with increased distance.For the cutting section with multi-stage soil slope,decay rate of acceleration was relatively larger.The acceleration level of the plane region ranged to 82.2-89.1 dB by the single C80 train.Yet the acceleration level caused by the C80 trains running parallel after meeting showed a distinct increment.The increment of the cutting section was much larger compared with the embankment section,with the increment ranging from 1.2-2.5 dB.In terms of the cutting section,Y direction acceleration was dominant closer to the track.Within 10-30 m of the track,the Y direction acceleration(perpendicular to the rail)decreased rapidly and became comparable to the X direction(parallel to the rail)and Z direction.Additionally,the cutting case generated a higher level of vibration in all three directions compared to the embankment,but as the distance from track increased,the deviation between acceleration gradually decreased.展开更多
Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the...Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the subgrade system. The dynamic responses of the coupled system were analyzed when the speed of train was 350 km/h and the transition was filled with graded broken stones mixed with 5% cement. The results indicate that the setting form of bridge-approach embankment section has little effect on the dynamic responses, thus designers can choose it on account of the practical circumstances. Because the location about 5 m from the bridge abutment has the greatest deformation, the stiffness within 0 5 m zone behind the abutment should be specially designed. The results of the study from vehicle track dynamics show that the maximum allowable track deflection angle should be 0.09% and the coefficient of subgrade reaction(K30) is greater than 190 MPa within the 0 5 m zone behind the abutment and greater than 150 MPa in other zones.展开更多
The study of radiation damage of high- molecular weight substances due to MeV ion interactions is of interest for engineering and scientific applications. In the present study polystyrene (PS) was irradiated with 107A...The study of radiation damage of high- molecular weight substances due to MeV ion interactions is of interest for engineering and scientific applications. In the present study polystyrene (PS) was irradiated with 107Ag ions of three different charge states (q) 11+, 14+ and 25+ and of 130 MeV energy. The emission of hydrogen from PS was monitored as a function of the incident ion fluence. The experimental results showed that the hydrogen depletion per incident ion from PS varies as qn, where n was found to be 2.1 as compared to the value 2.7 to 3.0 reported in the literature. Radii of the nanometric damaged zones or ion tracks formed were analyzed from the slope of the hydrogen depletion versus ion fluence curves as a function of charge state of incident ion. These have values between 3.2 - 6.8 nm. These radii were found to depend upon the charge state of the incident ion and vary as qm, where m has the value 0.9.展开更多
文中建立考虑舵机伺服系统特性和风、流干扰的线性船舶动力学模型,确定仿真实验船舶的各个必要参数.引入最优控制策略,以航速为自变量设计不同航速下基于最优控制策略的PID(proportion integral differential)航向控制器OP-PID Controll...文中建立考虑舵机伺服系统特性和风、流干扰的线性船舶动力学模型,确定仿真实验船舶的各个必要参数.引入最优控制策略,以航速为自变量设计不同航速下基于最优控制策略的PID(proportion integral differential)航向控制器OP-PID Controller(optimal PID controller),在不同航速下分别采取PID和OP-PID进行了航向控制仿真.在航向控制器的基础上,结合航段跟踪决策算法、改进的LOS(line-of-sight)制导方法获取航向偏差,以航向偏差驱动OP-PID间接航迹控制器.以OP-PID和改进的LOS组成的航迹控制方法进行了静水环境中和外界干扰下的航迹控制仿真实验.结果表明:基于改进LOS制导方法和OP-PID航向控制器可以较好地跟踪弯曲航道计划航线,舵角和转向幅度均小于现有航迹控制器.展开更多
基金Natural Science Foundation of China under Grant No.51878242Hebei Natural Science Foundation of China under Grant Nos.E2017404013 and E2020404007。
文摘This paper presents a comparative analysis of ground vibration in three directions generated by a heavy-duty railway with various track sections.The vibration characteristics in the plane area were investigated by using matrix test measurements.Acceleration peak attenuation was faster within 25 m from the embankment,and the high-frequency vibration attenuates faster with increased distance.For the cutting section with multi-stage soil slope,decay rate of acceleration was relatively larger.The acceleration level of the plane region ranged to 82.2-89.1 dB by the single C80 train.Yet the acceleration level caused by the C80 trains running parallel after meeting showed a distinct increment.The increment of the cutting section was much larger compared with the embankment section,with the increment ranging from 1.2-2.5 dB.In terms of the cutting section,Y direction acceleration was dominant closer to the track.Within 10-30 m of the track,the Y direction acceleration(perpendicular to the rail)decreased rapidly and became comparable to the X direction(parallel to the rail)and Z direction.Additionally,the cutting case generated a higher level of vibration in all three directions compared to the embankment,but as the distance from track increased,the deviation between acceleration gradually decreased.
基金Project(41030742) supported by the National Natural Science Foundation of ChinaProject(2009G010-c) supported by the Technological Research and Development Programs of the Ministry of Railways,China
文摘Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the subgrade system. The dynamic responses of the coupled system were analyzed when the speed of train was 350 km/h and the transition was filled with graded broken stones mixed with 5% cement. The results indicate that the setting form of bridge-approach embankment section has little effect on the dynamic responses, thus designers can choose it on account of the practical circumstances. Because the location about 5 m from the bridge abutment has the greatest deformation, the stiffness within 0 5 m zone behind the abutment should be specially designed. The results of the study from vehicle track dynamics show that the maximum allowable track deflection angle should be 0.09% and the coefficient of subgrade reaction(K30) is greater than 190 MPa within the 0 5 m zone behind the abutment and greater than 150 MPa in other zones.
文摘The study of radiation damage of high- molecular weight substances due to MeV ion interactions is of interest for engineering and scientific applications. In the present study polystyrene (PS) was irradiated with 107Ag ions of three different charge states (q) 11+, 14+ and 25+ and of 130 MeV energy. The emission of hydrogen from PS was monitored as a function of the incident ion fluence. The experimental results showed that the hydrogen depletion per incident ion from PS varies as qn, where n was found to be 2.1 as compared to the value 2.7 to 3.0 reported in the literature. Radii of the nanometric damaged zones or ion tracks formed were analyzed from the slope of the hydrogen depletion versus ion fluence curves as a function of charge state of incident ion. These have values between 3.2 - 6.8 nm. These radii were found to depend upon the charge state of the incident ion and vary as qm, where m has the value 0.9.
