Based on the stress distribution characteristics of rock burst multiple sites, the criterion of horizontal stress inducing layer dislocation rock burst was established. Accordingly, the influencing factors were analyz...Based on the stress distribution characteristics of rock burst multiple sites, the criterion of horizontal stress inducing layer dislocation rock burst was established. Accordingly, the influencing factors were analyzed. The analysis results indicate that the stress condition, edge of etastic zone depth, supporting strength, and the friction angle and cohesion among coal stratum, roof and floor are sensitive factors. By introducing double-couple model, the layer dislocation rock burst was explained and the energy radiation characteristics were analyzed. The SOS micro-seismic monitoring system was applied to observe the rock burst hazards about a mining face. The results show that P- and S-wave energy radiations produced by rock burst have directional characteristics. The energy radiation characteristics of the 22 rock bursts occurring on 79Z6 long-wall face are basically the same as theoretical results, that is, the ratio of S-wave energy of sensor 4 to 6 is about 1.5 and that of P-wave is smaller than 0.5. The consistency of the monitored characteristics of the energy radiation theoretically increases with the total energy increasing.展开更多
A new method is proposed to suppress chatter, in which the ultrasonic elliptical vibration is added on the cutting tool edge. It results in the fact that the rake face of tool is separated from the chip and the direct...A new method is proposed to suppress chatter, in which the ultrasonic elliptical vibration is added on the cutting tool edge. It results in the fact that the rake face of tool is separated from the chip and the direction of the frictional force between the rake face and the chip is reversed in each cycle of elliptical vibration cutting. The experimental investigations show that the chatter can be suppressed effectively by adding ultrasonic elliptical vibration on the cutting tool edge. In order to make clear the reason of chatter suppression, the mechanism of chatter suppression is analyzed theoretically from the viewpoint of energy.展开更多
The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation an...The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation and lateral deformations of bridges.Equilibrium equations and natural boundary conditions of the track-bridge system are established based on the energy variational principle,and an analytical solution is derived for the track deformation accounting for lateral bridge deformations.A five-span simply-supported bridge with continuous welded rail has been selected as the case study.The mapping rail deformations are compared to the finite element results,and both results agree well with each other,validating the analytical method proposed in this paper.The influence factors on the mapping rail deformation are further evaluated.Results show that the mapping rail deformation is consistent with the girder displacement at the area that is away from the girder ends when the flexural stiffness ratio between the track and the bridge girder is low.The interlayer stiffness has a significant effect on the mapping rail deformation when the track flexural stiffness is of a high value.展开更多
针对庞特里亚金极小值原理(Pontryagin's minimum principle, PMP)仅适用于离线计算且难以实车应用的问题,提出了一种基于麻雀搜索优化密度聚类(density-based spatial clustering of applications with noise, DBSCAN)的工况在线...针对庞特里亚金极小值原理(Pontryagin's minimum principle, PMP)仅适用于离线计算且难以实车应用的问题,提出了一种基于麻雀搜索优化密度聚类(density-based spatial clustering of applications with noise, DBSCAN)的工况在线识别能量管理策略。该策略结合离线训练与在线控制,并充分利用公交车线路固定性与片段性特征,以公交站为节点,将线路划分为多个驾驶片段。在车辆靠站期间,对上一个驾驶片段的电机输出功率进行工况识别,从而计算下一个驾驶片段的协态变量(co-state);在车辆开始运行时,将计算好的co-state应用于PMP算法中完成功率的实时分配。最后,通过构建基于实车数据的仿真实验,将所提出的策略移植到整车控制器中。结果显示,与当前实车运行的规则能量管理策略相比,该策略可减少等效氢耗17.6%,并能有效维持动力电池荷电状态(state of charge, SOC)。且每步计算均在60 ms以内,具有良好的实时性,能够满足燃料电池公交车实际运行中对能量管理策略的应用要求。展开更多
基金Project(2012LWB63) supported by the Fundamental Research Funds for the Central Universities, ChinaProject(SZBF2011-6-B35) supported by the Priority Acadamic Program Development of Jiangsu Higher Education Institutions (PAPD),China
文摘Based on the stress distribution characteristics of rock burst multiple sites, the criterion of horizontal stress inducing layer dislocation rock burst was established. Accordingly, the influencing factors were analyzed. The analysis results indicate that the stress condition, edge of etastic zone depth, supporting strength, and the friction angle and cohesion among coal stratum, roof and floor are sensitive factors. By introducing double-couple model, the layer dislocation rock burst was explained and the energy radiation characteristics were analyzed. The SOS micro-seismic monitoring system was applied to observe the rock burst hazards about a mining face. The results show that P- and S-wave energy radiations produced by rock burst have directional characteristics. The energy radiation characteristics of the 22 rock bursts occurring on 79Z6 long-wall face are basically the same as theoretical results, that is, the ratio of S-wave energy of sensor 4 to 6 is about 1.5 and that of P-wave is smaller than 0.5. The consistency of the monitored characteristics of the energy radiation theoretically increases with the total energy increasing.
文摘A new method is proposed to suppress chatter, in which the ultrasonic elliptical vibration is added on the cutting tool edge. It results in the fact that the rake face of tool is separated from the chip and the direction of the frictional force between the rake face and the chip is reversed in each cycle of elliptical vibration cutting. The experimental investigations show that the chatter can be suppressed effectively by adding ultrasonic elliptical vibration on the cutting tool edge. In order to make clear the reason of chatter suppression, the mechanism of chatter suppression is analyzed theoretically from the viewpoint of energy.
基金Project(2021RC2011)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProjects(U1934207,52178180)supported by the National Natural Science Foundation of ChinaProject(2021M703648)supported by the China Postdoctoral Science Foundation。
文摘The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation and lateral deformations of bridges.Equilibrium equations and natural boundary conditions of the track-bridge system are established based on the energy variational principle,and an analytical solution is derived for the track deformation accounting for lateral bridge deformations.A five-span simply-supported bridge with continuous welded rail has been selected as the case study.The mapping rail deformations are compared to the finite element results,and both results agree well with each other,validating the analytical method proposed in this paper.The influence factors on the mapping rail deformation are further evaluated.Results show that the mapping rail deformation is consistent with the girder displacement at the area that is away from the girder ends when the flexural stiffness ratio between the track and the bridge girder is low.The interlayer stiffness has a significant effect on the mapping rail deformation when the track flexural stiffness is of a high value.
文摘针对庞特里亚金极小值原理(Pontryagin's minimum principle, PMP)仅适用于离线计算且难以实车应用的问题,提出了一种基于麻雀搜索优化密度聚类(density-based spatial clustering of applications with noise, DBSCAN)的工况在线识别能量管理策略。该策略结合离线训练与在线控制,并充分利用公交车线路固定性与片段性特征,以公交站为节点,将线路划分为多个驾驶片段。在车辆靠站期间,对上一个驾驶片段的电机输出功率进行工况识别,从而计算下一个驾驶片段的协态变量(co-state);在车辆开始运行时,将计算好的co-state应用于PMP算法中完成功率的实时分配。最后,通过构建基于实车数据的仿真实验,将所提出的策略移植到整车控制器中。结果显示,与当前实车运行的规则能量管理策略相比,该策略可减少等效氢耗17.6%,并能有效维持动力电池荷电状态(state of charge, SOC)。且每步计算均在60 ms以内,具有良好的实时性,能够满足燃料电池公交车实际运行中对能量管理策略的应用要求。
