功能性动作筛查(Functional Movement Screen)是由美国物理治疗师Gray Cook等设计的一种身体功能评价方法,是一种革新性的动作模式评价系统,它简便易行,可以广泛用于各类人群的基本运动功能的评价。该方法通过测试功能性动作、肌肉控制...功能性动作筛查(Functional Movement Screen)是由美国物理治疗师Gray Cook等设计的一种身体功能评价方法,是一种革新性的动作模式评价系统,它简便易行,可以广泛用于各类人群的基本运动功能的评价。该方法通过测试功能性动作、肌肉控制、神经系统稳定等方面的表现来发现受测者身体灵活性与稳定性方面的不足,进而分析受测者在运动过程中潜在的动作补偿问题,从而保证人体动力链系统功能完善,降低运动损伤的发生几率。功能性动作筛查由深蹲测试、跨栏测试、直线弓箭步测试、肩关节活动度测试、主动直腿抬高测试、躯干稳定俯卧撑测试和旋转稳定测试7个子项目构成。运用文献资料法对我国功能性动作筛查的发展现状进行归纳整理,为广大学者的研究和教练员的应用提供理论参考。展开更多
To study the vehicle hunting behavior and its coupling with car body vibrations,a simplified lateral-dynamics-intended railway vehicle model is developed.A two-truck vehicle is modeled as a 17 degrees-of-freedom rigid...To study the vehicle hunting behavior and its coupling with car body vibrations,a simplified lateral-dynamics-intended railway vehicle model is developed.A two-truck vehicle is modeled as a 17 degrees-of-freedom rigid system,into which the car body flexural vibrations of torsion and bending modes are further integrated.The wheel/rail interaction employs a real-time calculation for the Hertzian normal contact,in which the nonlinear curvatures of wheel and rail profiles are presented as functions of wheelset lateral movement and/or yaw rotation.Then the tangential/creep forces are analytically expressed as the Hertzian contact patch geometry,and lead to a continuous and fast calculation compared to a look-up table interpolation.It is shown that the hunting frequencies of the vehicle model and a truck model differ significantly,which verifies the necessity of the whole vehicle model.In the case of low wheel/rail conicity,the hunting frequency increases linearly with vehicle speed,whereas it rises slowly at high speed for a large conicity.Comparison of hunting frequency and damping ratio between various conicities shows that first hunting(car body hunting)may occur when the vehicle is operated at a low speed in a small conicity case,while a second hunting(truck hunting)appears when the vehicle is operated at a high speed in a large conicity case.Stability analysis of linear and nonlinear vehicle models was carried out through coast down method and constant speed simulations.Results tell that the linear one overestimates the lateral vibrating.Whereas the structural vibrations of car body can be ignored in the stability analysis.Compared to existing simplified models for hunting stability study,the proposed simplified vehicle model released limitations in the nonlinear geometries of wheel/rail profiles,and it is suitable for a frequency-domain analysis by deriving the analytical expressions of the normal and tangential wheel/rail contact forces.展开更多
文摘功能性动作筛查(Functional Movement Screen)是由美国物理治疗师Gray Cook等设计的一种身体功能评价方法,是一种革新性的动作模式评价系统,它简便易行,可以广泛用于各类人群的基本运动功能的评价。该方法通过测试功能性动作、肌肉控制、神经系统稳定等方面的表现来发现受测者身体灵活性与稳定性方面的不足,进而分析受测者在运动过程中潜在的动作补偿问题,从而保证人体动力链系统功能完善,降低运动损伤的发生几率。功能性动作筛查由深蹲测试、跨栏测试、直线弓箭步测试、肩关节活动度测试、主动直腿抬高测试、躯干稳定俯卧撑测试和旋转稳定测试7个子项目构成。运用文献资料法对我国功能性动作筛查的发展现状进行归纳整理,为广大学者的研究和教练员的应用提供理论参考。
基金The project was supported by the National Natural Science Foundation of China(Grants 51805451,U1934202,and U2034210)the Sichuan Science and Technology Plan Project(Grant 2020YJ0074)+1 种基金the Fundamental Research Funds for the Central Universities(Grant 2682019CX43)the TPL Independent R&D Project(Grants 2018TPL_T08 and 2019TPL_T15).
文摘To study the vehicle hunting behavior and its coupling with car body vibrations,a simplified lateral-dynamics-intended railway vehicle model is developed.A two-truck vehicle is modeled as a 17 degrees-of-freedom rigid system,into which the car body flexural vibrations of torsion and bending modes are further integrated.The wheel/rail interaction employs a real-time calculation for the Hertzian normal contact,in which the nonlinear curvatures of wheel and rail profiles are presented as functions of wheelset lateral movement and/or yaw rotation.Then the tangential/creep forces are analytically expressed as the Hertzian contact patch geometry,and lead to a continuous and fast calculation compared to a look-up table interpolation.It is shown that the hunting frequencies of the vehicle model and a truck model differ significantly,which verifies the necessity of the whole vehicle model.In the case of low wheel/rail conicity,the hunting frequency increases linearly with vehicle speed,whereas it rises slowly at high speed for a large conicity.Comparison of hunting frequency and damping ratio between various conicities shows that first hunting(car body hunting)may occur when the vehicle is operated at a low speed in a small conicity case,while a second hunting(truck hunting)appears when the vehicle is operated at a high speed in a large conicity case.Stability analysis of linear and nonlinear vehicle models was carried out through coast down method and constant speed simulations.Results tell that the linear one overestimates the lateral vibrating.Whereas the structural vibrations of car body can be ignored in the stability analysis.Compared to existing simplified models for hunting stability study,the proposed simplified vehicle model released limitations in the nonlinear geometries of wheel/rail profiles,and it is suitable for a frequency-domain analysis by deriving the analytical expressions of the normal and tangential wheel/rail contact forces.
