0 INTRODUCTION Pressure-stress coupling(PSC)refers to the bidirectional mechanical interaction between pore pressure and in-situ stress within subsurface formations(Hillis,2000).Variations in pore pressure redistribut...0 INTRODUCTION Pressure-stress coupling(PSC)refers to the bidirectional mechanical interaction between pore pressure and in-situ stress within subsurface formations(Hillis,2000).Variations in pore pressure redistribute the stress field,while evolving stress states in turn alter pore pressure.This reciprocity,governed by poroelasticity and multiphysics interactions,underlies a wide spectrum of geomechanical processes,including fracture initiation,fluid migration,reservoir evolution,and fault slip or seismicity(Xu et al.,2020).Conventional theories often treat pressure and stress as independent variables.展开更多
Based on the stability theory of linear time-varying continuous system, this paper investigates the synchronization of two linear bidirectionally-coupled systems. Sufficient conditions for asymptotic synchronization a...Based on the stability theory of linear time-varying continuous system, this paper investigates the synchronization of two linear bidirectionally-coupled systems. Sufficient conditions for asymptotic synchronization are obtained for general chaotic system with bidirectional coupling via linear error feedback. Since the trajectory of chaotic system is continuous and bounded, one can choose suitable coupled pararneters to satisfy the proposed criterion. The criterion can also be applied to the global synchronization for chaotic systems with linear unidirectional coupling. The chaotic Chen system and the generalized Lorenz-like system are taken as examples, the simulations verify the effectiveness of the proposed method.展开更多
Traditional power supply method for moving electric railway vehicles is based on contact type power collection technology.This sometimes cannot meet the requirements of modern rail transportation.A new wireless power ...Traditional power supply method for moving electric railway vehicles is based on contact type power collection technology.This sometimes cannot meet the requirements of modern rail transportation.A new wireless power transfer(WPT)technology can offer significant benefits in modern rail transportation particularly in some stringent environments.This paper reviews the status and the development of rail transit power supply technology,and introduces a new challenging technology--inductive power transfer(IPT)technology for rail transit.Tesla established the underpinning of IPT technology and creatively and significantly demonstrated power transfer by using highly resonant tuned coils long time ago.However,only in recent years the IPT technology has been significantly improved including the transfer air-gap length,transfer efficiency,coupling factor,power transfer capability and so on.This is mainly due to innovative semiconductor switches,higher control frequency,better coil designs and high performance material,new track and vehicle construction techniques.Recent advances in IPT for rail transit and major milestones of the developments are summarized in this paper.Some important technical issues such as coupling coil structures,power supply schemes,segmentation switching techniques for long-distance power supply,and bidirectional IPT systems for braking energy feedback are discussed.展开更多
In this paper we study the chaos synchronization and anti-synchronization problems between two hyper-chaotic systems with bidirectional coupling,and present synchronization and anti-synchronization methods of chaotic ...In this paper we study the chaos synchronization and anti-synchronization problems between two hyper-chaotic systems with bidirectional coupling,and present synchronization and anti-synchronization methods of chaotic systems,based on timedelayed feedback.Coupling coefficients between the drive and response systems are different,which are supposed to be nonlinearly coupled.Based on the nonlinear control theory,the synchronization and anti-synchronization between two different time-delay hyper-chaotic systems are investigated.The condition of synchronization is derived according to the error dynamical systems.Numerical simulations show the effectiveness and feasibility of the proposed synchronous conditions.展开更多
掘进机回转台在截割煤岩时承受偏载荷及强冲击作用,其性能影响掘进机的工作效率及安全性。为探究掘进机回转台疲劳寿命的影响因素及最佳服役参数,提出了一种基于Kriging代理模型和DEM-MFBD(discrete element model-multi flexible body ...掘进机回转台在截割煤岩时承受偏载荷及强冲击作用,其性能影响掘进机的工作效率及安全性。为探究掘进机回转台疲劳寿命的影响因素及最佳服役参数,提出了一种基于Kriging代理模型和DEM-MFBD(discrete element model-multi flexible body dynamics,离散单元法-多柔性体动力学)双向耦合技术的回转台疲劳寿命预测方法。首先,建立了掘进机截割部与回转台的空间受力模型,明确了截割部与回转台的受力规律。然后,联合RecurDyn与EDEM软件对回转台进行双向刚柔耦合动力学仿真分析,获得了回转台在工作状态下的应力分布。最后,利用拉丁超立方抽样法选取15组掘进机服役参数作为输入,以回转台疲劳寿命为响应,建立了对应的Kriging代理模型,并利用粒子群优化算法对代理模型进行寻优,得到了回转台在最佳服役参数下的疲劳寿命。结果表明,当掘进机的截割头转速为54 r/min、回转台横摆速度为1.003 m/min、截割臂垂直摆角为7°时,回转台的疲劳寿命最长。结合DEM-MFBD双向耦合技术、Kriging代理模型与粒子群优化算法来探究掘进机的最佳服役参数,可为回转类部件的优化设计提供新思路。展开更多
入海口水闸在海水涨落潮影响下,地基渗流方向随潮汐周期性反转,形成复杂的双向脉动渗流环境,可能引发土体累积变形与结构失稳。为探究此类动态渗流机制对水闸安全性的影响,以淮河入海水道海口枢纽工程为背景,基于PLAXIS2D软件建立二维...入海口水闸在海水涨落潮影响下,地基渗流方向随潮汐周期性反转,形成复杂的双向脉动渗流环境,可能引发土体累积变形与结构失稳。为探究此类动态渗流机制对水闸安全性的影响,以淮河入海水道海口枢纽工程为背景,基于PLAXIS2D软件建立二维流固耦合模型,采用小应变(HSS)模型模拟土体在动态渗流下的复杂应力路径,系统分析结构和地基土体的位移响应、超孔隙水压力分布及塑性破坏演化规律。研究结果表明:双向脉动渗流对土体和结构的变形影响主要在水平方向,随着动水头差归零,结构竖向位移几乎也归零,但会残余较明显的水平位移,主要由塑性应变累积所致;双向脉动渗流过程中产生的超孔压绝对数值较小(小于5 k Pa),对稳定性影响有限。水位主动变化一侧的地表较易产生塑性破坏,在实际工程中应对该部位进行重点防护与监测。展开更多
基金supported by the National Natural Science Foundation of China(Nos.U24B6002,42488101)the Key R&D Program of Shandong Province,China(No.2024CXPT076)the Independent innovation research program of China University of Petroleum(East China)(No.21CX06001A)。
文摘0 INTRODUCTION Pressure-stress coupling(PSC)refers to the bidirectional mechanical interaction between pore pressure and in-situ stress within subsurface formations(Hillis,2000).Variations in pore pressure redistribute the stress field,while evolving stress states in turn alter pore pressure.This reciprocity,governed by poroelasticity and multiphysics interactions,underlies a wide spectrum of geomechanical processes,including fracture initiation,fluid migration,reservoir evolution,and fault slip or seismicity(Xu et al.,2020).Conventional theories often treat pressure and stress as independent variables.
基金This work was supported bythe National Natural Science Foundation (No .60174005) Natural Science Foundation of Jiangsu Province (No .BK2001054) .
文摘Based on the stability theory of linear time-varying continuous system, this paper investigates the synchronization of two linear bidirectionally-coupled systems. Sufficient conditions for asymptotic synchronization are obtained for general chaotic system with bidirectional coupling via linear error feedback. Since the trajectory of chaotic system is continuous and bounded, one can choose suitable coupled pararneters to satisfy the proposed criterion. The criterion can also be applied to the global synchronization for chaotic systems with linear unidirectional coupling. The chaotic Chen system and the generalized Lorenz-like system are taken as examples, the simulations verify the effectiveness of the proposed method.
基金This work was supported in part by the National Key R&D Program of China under Grant 2017YFB1201003.
文摘Traditional power supply method for moving electric railway vehicles is based on contact type power collection technology.This sometimes cannot meet the requirements of modern rail transportation.A new wireless power transfer(WPT)technology can offer significant benefits in modern rail transportation particularly in some stringent environments.This paper reviews the status and the development of rail transit power supply technology,and introduces a new challenging technology--inductive power transfer(IPT)technology for rail transit.Tesla established the underpinning of IPT technology and creatively and significantly demonstrated power transfer by using highly resonant tuned coils long time ago.However,only in recent years the IPT technology has been significantly improved including the transfer air-gap length,transfer efficiency,coupling factor,power transfer capability and so on.This is mainly due to innovative semiconductor switches,higher control frequency,better coil designs and high performance material,new track and vehicle construction techniques.Recent advances in IPT for rail transit and major milestones of the developments are summarized in this paper.Some important technical issues such as coupling coil structures,power supply schemes,segmentation switching techniques for long-distance power supply,and bidirectional IPT systems for braking energy feedback are discussed.
基金Supported by Scientific and Technological Research Project of The Education Department Henan Province(12B110012)
文摘In this paper we study the chaos synchronization and anti-synchronization problems between two hyper-chaotic systems with bidirectional coupling,and present synchronization and anti-synchronization methods of chaotic systems,based on timedelayed feedback.Coupling coefficients between the drive and response systems are different,which are supposed to be nonlinearly coupled.Based on the nonlinear control theory,the synchronization and anti-synchronization between two different time-delay hyper-chaotic systems are investigated.The condition of synchronization is derived according to the error dynamical systems.Numerical simulations show the effectiveness and feasibility of the proposed synchronous conditions.
文摘掘进机回转台在截割煤岩时承受偏载荷及强冲击作用,其性能影响掘进机的工作效率及安全性。为探究掘进机回转台疲劳寿命的影响因素及最佳服役参数,提出了一种基于Kriging代理模型和DEM-MFBD(discrete element model-multi flexible body dynamics,离散单元法-多柔性体动力学)双向耦合技术的回转台疲劳寿命预测方法。首先,建立了掘进机截割部与回转台的空间受力模型,明确了截割部与回转台的受力规律。然后,联合RecurDyn与EDEM软件对回转台进行双向刚柔耦合动力学仿真分析,获得了回转台在工作状态下的应力分布。最后,利用拉丁超立方抽样法选取15组掘进机服役参数作为输入,以回转台疲劳寿命为响应,建立了对应的Kriging代理模型,并利用粒子群优化算法对代理模型进行寻优,得到了回转台在最佳服役参数下的疲劳寿命。结果表明,当掘进机的截割头转速为54 r/min、回转台横摆速度为1.003 m/min、截割臂垂直摆角为7°时,回转台的疲劳寿命最长。结合DEM-MFBD双向耦合技术、Kriging代理模型与粒子群优化算法来探究掘进机的最佳服役参数,可为回转类部件的优化设计提供新思路。
文摘入海口水闸在海水涨落潮影响下,地基渗流方向随潮汐周期性反转,形成复杂的双向脉动渗流环境,可能引发土体累积变形与结构失稳。为探究此类动态渗流机制对水闸安全性的影响,以淮河入海水道海口枢纽工程为背景,基于PLAXIS2D软件建立二维流固耦合模型,采用小应变(HSS)模型模拟土体在动态渗流下的复杂应力路径,系统分析结构和地基土体的位移响应、超孔隙水压力分布及塑性破坏演化规律。研究结果表明:双向脉动渗流对土体和结构的变形影响主要在水平方向,随着动水头差归零,结构竖向位移几乎也归零,但会残余较明显的水平位移,主要由塑性应变累积所致;双向脉动渗流过程中产生的超孔压绝对数值较小(小于5 k Pa),对稳定性影响有限。水位主动变化一侧的地表较易产生塑性破坏,在实际工程中应对该部位进行重点防护与监测。
