Integration of bio-inspired limb-like structure damping into motor suspension of high-speed trains to enhance bogie hunting stability

Hunting stability is an important performance criterion in railway vehicles.This study proposes an incorporation of a bio-inspired limb-like structure(LLS)-based nonlinear damping into the motor suspension system for traction units to improve the nonlinear critical speed and hunting stability of high-speed trains(HSTs).Initially,a vibration transmission analysis is conducted on a HST vehicle and a metro vehicle that suffered from hunting motion to explore the effect of different motor suspension systems from on-track tests.Subsequently,a simplified lateral dynamics model of an HST bogie is established to investigate the influence of the motor suspension on the bogie hunting behavior.The bifurcation analysis is applied to optimize the motor suspension parameters for high critical speed.Then,the nonlinear damping of the bio-inspired LLS,which has a positive correlation with the relative displacement,can further improve the modal damping of hunting motion and nonlinear critical speed compared with the linear motor suspension system.Furthermore,a comprehensive numerical model of a high-speed train,considering all nonlinearities,is established to investigate the influence of different types of motor suspension.The simulation results are well consistent with the theoretical analysis.The benefits of employing nonlinear damping of the bio-inspired LLS into the motor suspension of HSTs to enhance bogie hunting stability are thoroughly validated.

Effect of suspension training on neuromuscular function, postural control, and knee kinematics in anterior cruciate ligament reconstruction patients

BACKGROUND Suspension training(SET)is a method of neuromuscular training that enables the body to carry out active training under unstable support through a suspension therapy system.However,there have been few reports in the literature on the application of SET to anterior cruciate ligament reconstruction(ACLR)patients.It is not clear what aspects of the patient's function are improved after SET.AIM To investigate the effect of SET on the neuromuscular function,postural control,and knee kinematics of patients after ACLR surgery.METHODS Forty participants were randomized to an SET group or a control group.The SET group subjects participated in a SET protocol over 6 wk.The control group subjects participated in a traditional training protocol over 6 wk.Isokinetic muscle strength of the quadriceps and hamstrings,static and dynamic posture stability test,and relative translation of the injured knee were assessed before and after training.RESULTS The relative peak torque of the quadriceps and hamstrings in both groups increased significantly(P<0.001),and the SET group increased by a higher percentage than those in the control group(quadriceps:P=0.004;hamstrings:P=0.011).After training,both groups showed significant improvements in static and dynamic posture stability(P<0.01),and the SET group had a greater change than the control group(P<0.05).No significant improvement on the relative translation of the injured knee was observed after training in either group(P>0.05).CONCLUSION Our findings show that SET promotes great responses in quadriceps and hamstring muscle strength and balance function in ACLR patients.

Deep learning-based fault diagnostic network of high-speed train secondary suspension systems for immunity to track irregularities and wheel wear

Fault detection and isolation of high-speed train suspension systems is of critical importance to guarantee train running safety. Firstly, the existing methods concerning fault detection or isolation of train suspension systems are briefly reviewed and divided into two categories, i.e., model-based and data-driven approaches. The advantages and disadvantages of these two categories of approaches are briefly summarized. Secondly, a 1D convolution network-based fault diagnostic method for highspeed train suspension systems is designed. To improve the robustness of the method, a Gaussian white noise strategy(GWN-strategy) for immunity to track irregularities and an edge sample training strategy(EST-strategy) for immunity to wheel wear are proposed. The whole network is called GWN-EST-1 DCNN method. Thirdly, to show the performance of this method, a multibody dynamics simulation model of a high-speed train is built to generate the lateral acceleration of a bogie frame corresponding to different track irregularities, wheel profiles, and secondary suspension faults. The simulated signals are then inputted into the diagnostic network, and the results show the correctness and superiority of the GWN-EST-1DCNN method. Finally,the 1DCNN method is further validated using tracking data of a CRH3 train running on a high-speed railway line.

A nonlinear control method for the electromagnetic suspension system of the maglev train

To deal with the inherent nonlinearity and open-loop instability of the electromagnetic suspension（EMS） system,a new nonlinear control method is proposed.The simulation results show that,for a PID controller,the over-shoot of the system response to an airgap step disturbance is about 3 mm,and the transient time is 6 s;however,for the proposed nonlinear controller,there is no overshoot and transient time within 2 s.The proposed method has a faster response and stronger robustness.With a designed bi-DSP suspension controller,this nonlinear control method was implemented on the Shanghai Urban Maglev Test Line（SUMTL） to validate its effectiveness and feasibility.

Measured load spectra of the bearing in high-speed train gearbox under different gear meshing conditions

The load spectrum is a crucial factor for assess-ing the fatigue reliability of in-service rolling element bear-ings in transmission systems.For a bearing in a high-speed train gearbox,a measurement technique based on strain detection of bearing outer ring was used to instrument the bearing and determine the time histories of the distributed load in the bearing under different gear meshing conditions.Accordingly,the load spectrum of the total radial load car-ried by the bearing was compiled.The mean value and class interval of the obtained load spectrum were found to vary non-monotonously with the speed and torque of gear mesh-ing,which was considered to be caused by the vibration of the shaft and the bearing cage.As the realistic service load input of bearing life assessment,the measured load spectrum under different gear meshing conditions can be used to pre-dict gearbox bearing life realistically based on the damage-equivalent principle and actual operating conditions.

Chylous ascites after whole pelvis suspension:case report and literature review

We report a case of Chylous ascites after whole pelvis suspension and to discuss the possible reasons. An 85-year-old female patient with anterior vaginal prolapse 1V （AVP IV）, vaginal vault proplapse IV and posterior vaginal prolapse IV （PVP IV）, developed Chylous ascites 2 weeks after she received whole pelvis suspension, The cause of chylous ascites in the present case was not associated with malignant tumor, hepatic cirrhosis, or inflammation. Therefore, surgical trauma may be considered the cause of disorder. X-ray lymphangioadenography should be performed to draw a final conclusion.

Clinical analysis of laparoscopic lateral peritoneal suspension in the treatment of severe pelvic organ prolapse

Objective:To investigate the clinical effects of laparoscopic lateral peritoneal suspension for severe pelvic organ prolapse(POP).Methods:Thirty-eight patients who underwent laparoscopic lateral peritoneal suspension for pelvic organ prolapse in the gynecology department of our hospital from January 2019 to January 2020 were selected for retrospective analysis.Postoperative outcomes were recorded for patients at 3,6,and 12 months postoperatively.Results:All 38 patients completed the surgery safely,and the duration of surgery was 85-190 min,with a mean of(138±40.75)min;surgical bleeding was 30-80 ml,with a mean of(57±35.4)ml;the duration of postoperative catheterization was 4-6 days,with a mean of(5±0.73)days;postoperative hospitalization was 6-12 days,with a mean of(8.49±2.18)days.2.18)days.At 3,6,and 12 months after the end of surgery,all follow-up patients had their uterus and anterior vaginal wall restored to normal position without prolapse.The pelvic floor rehabilitation of the patients after surgery was good and their sexual life was significantly improved in all cases.Conclusion:Laparoscopic lateral peritoneal suspension for severe pelvic organ prolapse is safe,efficacious,minimally traumatic,less painful,with short hospital stay,fast postoperative recovery,greater choice of uterine de-positioning,with the advantages of permanence and good pelvic floor anatomical recovery,and this procedure can maintain a certain vaginal length with 100%efficiency,which is worthy of clinical promotion.

基于无线Mesh网络技术的旅客列车服务信息系统研究

针对我国既有旅客列车服务信息系统存在的不足,本文在分析旅客旅行需求信息的基础上,提出基于无线Mesh网络技术的旅客列车服务信息系统设计方案,分析系统基本功能、网络架构以及系统关键技术。

无线Mesh网在城市轨道交通车地通信系统中的研究

无线Mesh网因组网灵活、支持范围大和移动性强等特点,使其在城市轨道交通(城轨)中具有很好的应用前景。尝试将无线Mesh网技术应用于城轨车地通信系统中,针对车地通信存在的越区切换问题,提出了一种基于车载MMS(mobile Mesh station)位置触发的越区切换方案,利用OPNET对组网方案和切换方案进行了仿真。仿真结果表明,无线Mesh组网方案性能优于传统WLAN组网方案性能,切换方案能有效降低时延并避免了假切换和乒乓切换的发生。

振动疗法联合悬吊训练前交叉韧带重建后患者运动及膝关节功能的变化

背景:物理疗法对前交叉韧带重建术后恢复至关重要。近年来,许多医师都在优化前交叉韧带重建术后的物理康复方案,但仍然缺乏高效的前交叉韧带重建术后康复训练疗法。目的:探讨振动疗法联合悬吊训练对前交叉韧带重建患者术后运动及膝关节功能的影响。方法:纳入在上海体育大学附属体育医院就诊的80例首次行单侧前交叉韧带重建患者,按照随机数字表法将患者随机分为振动疗法组和振动疗法+悬吊训练组,每组40例。振动疗法组患者在前交叉韧带重建术后第13周开始进行振动疗法训练(每次10 min,1次/d,每周6次),振动疗法+悬吊训练组患者在前交叉韧带重建术后第13周开始进行振动疗法(每次10 min,1次/d,每周6次)联合悬吊训练(每周2次),共训练8周。训练前及训练8后,采用膝关节Lysholm评分评价膝关节功能,采用等速肌力评估训练系统评估屈膝对称性指数,采用平衡测试系统评估双侧多轴平均轨迹误差差值。结果与结论:(1)与训练前比较,两组患者训练8周后的膝关节Lysholm评分、屈膝与伸膝对称性指数均升高(P<0.05),双侧多轴平均轨迹误差差值降低(P<0.05);与振动疗法组比较,振动疗法+悬吊训练组患者膝关节Lysholm评分、屈膝与伸膝对称性指数均升高(P<0.05),双侧多轴平均轨迹误差差值降低(P<0.05);(2)结果表明,与单独进行振动疗法相比,振动疗法联合悬吊训练可显著改善前交叉韧带重建患者的膝关节功能,增加肌肉力量和对称性,提高平衡稳定性。

基于链状无线Mesh网络的货运列车监控系统

在分析铁路货物运输特点的基础上,提出了基于无线Mesh网络的货运列车状态监控系统。以双模链状无线Mesh网络作为监控信息传输的通信网络,研究设计了基于Raspberry Pi平台的多媒体信息采集节点和智能的监控软件,实现了运输人员在货运机车中对在运物资的集中式、智能化监控。实验表明,该系统能够有效提高铁路货物运输的安全性和可靠性。

短定子磁浮列车基于悬浮间隙实现测速和定位的算法仿真及应用

短定子磁浮列车测速和定位技术实现方式与传统轮轨不同,目前有多种技术实现方式,但都需要在磁浮列车上设置测速和定位设备或系统,且与悬浮控制系统相互独立,但悬浮控制系统对速度信号和位置信号又有一定的依赖性。因此,设计了一种基于悬浮间隙实现测速和定位的算法,并通过仿真达到算法设计预期目的,最后通过编程将算法嵌入磁浮列车的悬浮控制系统硬件平台,实现测速和定位的算法应用,测速和定位信号完全集成于悬浮控制系统中,摆脱悬浮控制系统对外置测速定位系统的依赖,提升磁浮列车在轨道交通市场的竞争力。

基于无线Mesh网络技术的旅客列车宽带网络设计研究

随着高速铁路交通的发展,信息网络的移动接入技术需要得到相应的改善和提高。根据公共移动通信网和铁路专用移动通信网的发展现状,本文提出了一种基于无线Mesh网络技术的旅客列车服务宽带网络的设计方案,分析了网络结构、关键技术以及网络的应用场景。

Numerical simulation of sand load applied on high-speed train in sand environment

High-speed train running in the sand environment is different from the general environment. In the former situation, there will be sand load applied on high-speed train(SLAHT) caused by sand particles hitting train surface. This will have a great impact on the train stability, running drag and surface corrosion. Numerical simulation method of SLAHT in sand environment is studied. The velocity and mass flow rate models of saltation and suspension sand particles and the calculation model of SLAHT caused by sand particles hitting train surface are established. The discrete phase method is adopted for numerical simulating the process of saltation and suspension sand particles moving to train surface and generating sand load. By comparison with the field tests, the numerical simulation reliability is analysed. The theoretical formula of SLAHT changing with cross-wind and train speed is proposed. SLAHT changing law is analyzed. Research results indicate that SLAHT changing with cross-wind and train speed is a quadratic relationship. When train speed is constant, SLAHT increases quadratically with cross-wind speed improvement. When cross-wind speed is constant, SLAHT increases quadratically with train speed improvement.

Refined disturbance observer based prescribed performance fixed-time control of high-speed EMS trains with track irregularities

High-speed Electromagnetic Suspension(EMS)train is continuously impacted by the irregularity of the track,which worsens the levitation performance of the train.In this paper,a composite control scheme for the EMS is proposed to suppress track irregularities by integrating a Refined Disturbance Observer(RDO)and a Prescribed Performance Fixed-Time Controller(PPFTC).The RDO is designed to estimate precisely the track irregularities and lumped disturbances with uncertainties and exogenous disturbances in the suspension system,and reduce input chattering by applying to the disturbance compensation channel.PPFTC is designed to converge the suspension air gap error to equilibrium point with prescribed performance by completing error conversion,and solve the fast dynamic issue of EMS.And the boundary of overshoot and steady-state is limited in the ranged prescribed.A theoretical analysis is conducted on the stability of the proposed control method.Finally,the effectiveness and reasonability of the proposed composite anti-disturbance control scheme is verified by simulation results.

五位姿参数下车载永磁体与永磁轨道之间的磁力特性研究

永磁磁浮交通系统利用车载永磁体和永磁轨道间的磁斥力实现悬浮,理解并掌握永磁体磁力与其空间位姿参数的关系对磁浮车辆走行部及轨道结构设计具有重要意义.参考兴国县永磁磁浮交通系统,建立车载永磁体和永磁轨道的三维磁场有限元模型;计算不同悬浮间隙、横向偏移、点头角、侧滚角和摇头角条件下车载永磁体受到的磁力,重点分析车载永磁体悬浮力和横向力随5个位姿参数的变化规律及其相关程度.结果表明:车载永磁体的磁力主要受悬浮间隙和横向偏移量的影响,受摇头角的影响较大,受点头角和侧滚角的影响很小;在设定的参数变化范围内,悬浮力最小值和最大值与额定悬浮力之比分别约为0.75和1.16,横向力最大值达到额定悬浮力的50.42%;车载永磁体横向力的方向与其横向偏移方向一致,摇头力矩与其摇头方向相同,需要为永磁悬浮系统设置导向装置,防止车载永磁体横向晃动和偏航运行.

基于遗传算法的悬浮电磁铁磁热耦合参数优化

中低速磁浮列车依靠悬浮电磁铁产生电磁吸力,实现悬浮和导向,针对悬浮电磁铁结构参数设计问题,提出一种基于磁热耦合仿真的方法对悬浮电磁铁进行优化研究。通过对电磁铁结构分析,提出对悬浮电磁铁进行内扣和外扣两种方式,并分别建立三维有限元参数化计算模型,分析其主要发热源和热流量计算方法。在电磁铁温升不超过设定值的情况下,以提升悬浮电磁铁的浮重比为目标,采用遗传算法对结构参数进行寻优求解。仿真试验结果表明,在保证悬浮力达到要求的情况下,所提方法对电磁铁进行内扣操作后,其质量减少43%,进行外扣操作后,电磁铁质量减少58%,并且电磁铁的稳态温升没有超过设定值。所提出的设计方案更加符合实际,为后续设计提供一定的参考依据。

轨道不平顺激励对高温超导磁浮列车电机悬挂的影响

高温超导磁浮列车在运行过程中受到轨道随机不平顺激励的影响,车体和磁浮架的振动会传递至直线电机动子而导致气隙变化,变化后的电磁力反作用于电机悬挂系统,进而影响磁浮架和车体振动。二者的耦合振动一定程度上会影响高温超导磁浮列车的安全运行。为了减少轨道随机不平顺激励对电机悬挂系统的影响,文章建立了多刚体动力学理论模型,并在周期性激励的作用下,对理论模型进行了动力学响应的仿真验证,证明了动力学理论模型的正确性。进一步地,在UM软件中以电机法向力和轨道随机不平顺作为外部激励,对高温超导磁浮列车动力学模型进行仿真,研究了电机悬挂系统的垂向刚度对直线电机气隙、车体和悬浮架振动、列车运行平稳性等参数的影响并对该刚度值进行了合理优化。结果表明:增大直线电机悬挂系统的垂向刚度能一定程度提高车体平稳性;同时增大垂向刚度能一定程度上减小气隙的变化和电机的振动,从而降低和悬浮架的耦合作用。研究结果是在特定的结构参数、负载条件下的仿真分析结果,可为高温超导磁浮列车动力学分析提供一定参考作用。

齿轨铁路齿条啮合与轮轨滚动接触间耦合作用机理分析

针对适于山地轨道交通的齿轨铁路,建立基于显式时间积分的三维齿轨轮对-轨道瞬态接触有限元模型,模型可分析齿轮齿条啮合和轮轨滚动接触间中、高频耦合动力作用。轮对和轨道真实几何,齿轮与车轮轮径差导致“车轮悖论”现象及结构振动等均有考虑,齿轮齿条啮合和轮轨接触采用集成库仑摩擦的“面-面”接触算法求解。对比零和非零轮轨摩擦系数工况,解构“车轮悖论”现象对动态接触的影响。以初步设计的Strub型齿轨铁路为例,分析速度为10 km/h和0‰、240‰、480‰坡度下动态接触现象。结果表明,受齿轮啮合影响,齿条、轮轨接触力均呈现周期性波动,但垂向接触总力和总牵引扭矩分别在重力载荷与牵引扭矩附近波动。“车轮悖论”使齿条垂向力和法向接触应力减小,而轮轨垂向力和法向接触应力增加,齿面切向接触应力与接触斑内滑移区面积相应增加,在坡度240‰下,轮轨摩擦系数由0增至0.2,齿条、轮轨最大法向接触应力由248.69、752.66 MPa增至195.17、757.44 MPa,最大切向接触应力相应由24.48、152.84 MPa变成21.31、2.14 MPa。轮轨接触斑因发生显著蠕滑呈现全滑移。相同速度及摩擦条件下,坡度增加使齿条垂向力和牵引力增加,轮轨垂向力和牵引力减小,接触应力呈同相变化。

高精度经颅直流电刺激联合悬吊运动训练对脑卒中患者下肢运动功能的影响

目的 观察高精度经颅直流电刺激(HD-tDCS)联合悬吊运动训练对脑卒中患者下肢运动功能的影响。方法 选择2022年1月-2023年2月在山东大学附属山东省立第三医院康复医学部住院治疗的脑卒中患者120例,按照随机数字表法分为对照组、HD-tDCS组、悬吊组和联合治疗组,每组30例。治疗过程中有4例因中途出院无法继续接受治疗而脱落,其中对照组3例,HD-tDCS组1例,最终对照组、HD-tDCS组、悬吊组和联合治疗组分别纳入27、29、30、30例。对照组接受运动疗法和神经肌肉电刺激等常规康复治疗,25 min/d,1次/d,5 d/周,持续治疗8周;HD-tDCS组在对照组基础上接受HD-tDCS治疗,主要刺激电极置于偏瘫侧脑初级运动皮层M1区(C3/C4),4个接受极分别置于M1区四周约3.5 cm处的C1/C2、C5/C6、FC3/FC4、CP3/CP4区,电流恒定强度2 mA,电流起伏时间30 s,20 min/次,1次/d,5 d/周,持续治疗8周;悬吊组在对照组基础上接受偏瘫侧下肢分离组合运动、动态闭链稳定运动、骨盆摆动和放松运动等悬吊运动训练,25 min/次,1次/d,5 d/周,持续治疗8周;联合治疗组在对照组基础上接受HD-tDCS联合悬吊运动训练。分别于治疗前和治疗4、8周后,采用Fugl-Meyer运动功能量表下肢部分(FMA-LE)评定患者下肢运动功能;采用Berg平衡量表(BBS)评定患者平衡功能;采用功能性步行能力量表(FAC)评定患者功能性步行能力;采用视频步态分析系统评定患者步态时空参数(步频、步速、步长和步行周期)。结果 与治疗前比较,4组治疗4、8周后FMA-LE评分、BBS评分、FAC等级及步态时空参数(步频、步速、步长和步行周期)均明显提高,差异具有统计学意义(P<0.05)。与对照组、HD-tDCS组、悬吊组同一时间点比较,联合治疗组治疗4、8周后FMA-LE、BBS评分均明显更高,治疗8周后FAC等级及步态时空参数(步频、步速、步长及步行周期)均明显更高,差异具有统计学意义(P<0.05)。结论 HD-tDCS联合悬吊运动训练可有效提高脑卒中患者下肢运动功能、平衡能力和步行能力,值得临床推广应用。