Running safety assessment method of trains under seismic conditions based on the derailment risk domain

The accurate assessment of running safety during earthquakes is of significant importance for ensuring the safety of railway lines.Currently,assessment methods based on a single index suffer from issues such as misjudgment of operational safety and difficulty in evaluating operational margin,making them unsuitable for assessing train safety during earthquakes.Therefore,in order to propose an effective evaluation method for the running safety of trains during earthquakes,this study employs three indexes,namely lateral displacement of the wheel–rail contact point,wheel unloading rate,and wheel lift,to describe the lateral and vertical contact states between the wheel and rail.The corresponding evolution characteristics of the wheel–rail contact states are determined,and the derailment forms under different frequency components of seismic motion are identified through dynamic numerical simulations of the train–track coupled system under sine excitation.The variations in the wheel–rail contact states during the transition from a safe state to the critical state of derailment are analyzed,thereby constructing the evolutionary path of train derailment and seismic derailment risk domain.Lastly,the wheel–rail contact and derailment states under seismic conditions are analyzed,thus verifying the effectiveness of the evaluation method for assessing running safety under earthquakes proposed in this study.The results indicate that the assessment method based on the derailment risk domain accurately and comprehensively reflects the wheel–rail contact states under seismic conditions.It successfully determines the forms of train derailment,the risk levels of derailment,and the evolutionary paths of derailment risk.

Safety of the express freight train running over a long-span bridge

Purpose-Express freight transportation is in rapid development currently.Owing to the higher speed of express freight train,the deformation of the bridge deck worsens the railway line condition under the action of wind and train moving load when the train runs over a long-span bridge.Besides,the blunt car body of vehicle has poor aerodynamic characteristics,bringing a greater challenge on the running stability in the crosswind.Design/methodology/approach-In this study,the aerodynamic force coefficients of express freight vehicles on the bridge are measured by scale model wind tunnel test.The dynamic model of the train-long-span steel truss bridge coupling system is established,and the dynamic response as well as the running safety of vehicle are evaluated.Findings-The results show that wind speed has a significant influence on running safety,which is mainly reflected in the over-limitation of wheel unloading rate.The wind speed limit decreases with train speed,and it reduces to 18.83 m/s when the train speed is 160 km/h.Originality/value-This study deepens the theoretical understanding of the interaction between vehicles and bridges and proposes new methods for analyzing similar engineering problems.It also provides a new theoretical basis for the safety assessment of express freight trains.

Improvement of heat-tolerance by training I. Evaluation of effects of long-distance running and march training on heat-tolerance

in order to verify the heat-tolerance effect, two trainings, 90 min marching with load (WBGT 24. 6～35.6℃) and 10 km running (WBGT 25.0～31.1℃) were performed in laboratory and field under hot climate.Ten to twelve times (days) of training were carried out

Effects of intermittent sprint and plyometric training on endurance running performance

Purpose:The purpose of this study was to compare the effects of intermittent sprint training and plyometric training on endurance running performance.Methods:Fourteen moderately trained male endurance runners were allocated into either the intermittent sprint training group(n = 7)or the plyometric training group(n = 7).The preliminary tests required subjects to perform a treadmill graded exercise test,a countermovement jump test for peak power measurement,and a 10-km time trial.Training included 12 sessions of either intermittent sprint or plyometric training carried out twice per week.On completion of the intervention,post-tests were conducted.Results:Both groups showed significant reduction in weekly training mileage from pre-intervention during the intervention period.There were significant improvements in the 10-km time trial performance and peak power.There was also significant improvement in relative peak power for both groups.The 10-km time trial performance and relative peak power showed a moderate inverse correlation.Conclusion:These findings showed that both intermittent sprint and plyometric training resulted in improved 10-km running performance despite reduction in training mileage.The improvement in running performance was accompanied by an improvement in peak power and showed an inverse relationship with relative peak power.

Running slow or running fast;that is the question:The merits of high-intensity interval training

In a recent issue of the Journal of Sport and Health Science,García-Pinillos et al.~1 reviewed evidence on the effects of highintensity intermittent training(interval training)(HIIT)on muscular and performance adaptations in recreational runners.

Study on Development of Train Running Diagram Optimization

This article from a whole new perspective on existing studies was classified, from the specific issues addressed by starting on two key issues of recent train scheduling plan: train running diagram and train operation adjustment. Solutions, basic ideas and researches are discussed in detail. Among them, the train working diagram is divided into single and double lane sections and Passenger Train Running Diagram. And the train operation adjustment includes the real-time adjustment, the service of train insert and the conflict prediction. This paper introduces automatic train operation dispatching system in scheduling applications, and discusses the train scheduling problems and the future direction of development.

How does high-intensity intermittent training affect recreational endurance runners? Acute and chronic adaptations: A systematic review

Objective: This systematic review aimed to critically analyze the literature to determine how high-intensity intermittent training(HIIT) affects recreational endurance runners in the short-and long-term.Methods: Electronic databases were searched for literature dating from January 2000 to October 2015. The search was conducted using the key words "high-intensity intermittent training" or "high-intensity interval exercise" or "interval running" or "sprint interval training" and "endurance runners" or "long distance runners". A systematic approach was used to evaluate the 783 articles identified for initial review. Studies were included if they investigated HIIT in recreational endurance runners. The methodological quality of the studies was evaluated using the Physiotherapy Evidence Database(PEDro) scale(for intervention studies) and the modified Downs and Black Quality Index(for cross-sectional studies).Results: Twenty-three studies met the inclusionary criteria for review. The results are presented in 2 parts: cross-sectional(n = 15) and intervention studies(n = 8). In the 15 cross-sectional studies selected, endurance runners performed at least 1 HIIT protocol, and the acute impact on physiological, neuromuscular, metabolic and/or biomechanical variables was assessed. Intervention studies lasted a minimum of 4 weeks, with 10 weeks being the longest intervention period, and included 2 to 4 HIIT sessions per week. Most of these studies combined HIIT sessions with continuous run(CR) sessions; 2 studies' subjects performed HIIT exclusively.Conclusion: HIIT-based running plans(2 to 3 HIIT sessions per week, combining HIIT and CR runs) show athletic performance improvements in endurance runners by improving maximal oxygen uptake and running economy along with muscular and metabolic adaptations. To maximize the adaptations to training, both HIIT and CR must be part of training programs for endurance runners.

Kinematic alterations after two high-intensity intermittent training protocols in endurance runners

Purpose:This study aimed to evaluate running kinematic characteristics during the early and late stages of 2 high-intensity intermittent training(HIIT)protocols with similar external load but different average running pace,as well as to compare the fatigue-induced changes during both HIIT protocols at a kinematic level.Methods:Eighteen endurance runners were tested on a track on 2 occasions:10 runs of 400 m with 90-120 s recovery between running bouts(10 × 400 m),and 40 runs of 100 m with 25-30 s recovery between running bouts(40 × 100 m).Heart rate was monitored during both protocols;blood lactate accumulation and rate of perceived exertion were recorded after both exercises.A high-speed camera was used to measure sagittalplane kinematics at the first and last runs during both HIIT protocols.The dependent variables were spatial-temporal parameters(step length and contact and flight time),joint angles during support(relative angles of the hip,knee,and ankle),and foot strike pattern.Results:High levels of exhaustion were reached by the athletes during both workouts(blood lactate accumulation>12 mmol/L,rate of perceived exertion>15;peak heart rate(HRpeak)>176 bpm).A within-protocol paired t test(first vs.last run)revealed no significant changes(p≥0.05)in kinematic variables during any of the HIIT sessions.A between-protocol comparison with the first run of each protocol revealed the effect of running speed on kinematics:+2.44 km/h during the 40 × 100 m:shorter contact and flight time(p<0.01)and longer step length(p= 0.001);greater hip flexion(p = 0.031)and ankle extension(p = 0.001)at initial contact;smaller knee and ankle flexion(p<0.001)at midstance;and greater hip extension at toe-off(p<0.001).Conclusion:HIIT sessions including runs for 15-90 s and performed at intensity above the velocity associated with maximal oxygen uptake did not consistently perturb the running kinematics of trained endurance runners.

Experiments on Transformation and Run-Up of Wave Trains

This paper. details experiments undertaken in the UK Coastal Research Facility (CRF)at Hy draulies Research (HR), Wallingford, on transformation and run-up of wave trains. The purpose of these experiments is to provide verification data for numerical models of wave transformation in shoaling. surf and swash zones. This is the kind of data ih:lt flume experiments are unable to provide, and is collected in the highly controlled environment of CRF where extrinsic factors present in the field are not an issue. The experiments concerning wave trains are undertaken by use of existing wave generation software, and the run-up measurements are made with large experimental run-up gauges.

The Train Runs Faster

Teacher:Why does a train run faster than(比)a car?Pupil:Because it has more wheels(轮子)than a car.

侧风下大跨拱桥变形对高速列车行车平稳性的影响机理

为探求侧风下的拱桥变形对列车平稳性的作用机理,通过风-车-桥耦合系统得到跨中横、竖向位移,分析不同风速、车速下的列车行车平稳性,量化桥梁变形对风-车-桥系统中列车横、竖向加速度的贡献;结合车体加速度响应的敏感波长及桥梁变形的时频特性,分析桥梁变形对行车平稳性影响机理.结果表明:桥梁竖向位移差异较横向位移差异较小,且主要位移由车致桥梁变形产生,最大幅值达到了-9.2mm;在列车及风荷载作用下,桥梁横向及竖向位移较为显著,但其对列车平稳性的影响主要体现在交界墩位置处,约为其余位置响应的4倍;除交界墩区域,桥上列车的行车平稳性主要由风致列车振动及轨道不平顺决定;车体横向及竖向加速度功率谱密度分布与轨道不平顺的波长密切相关,其对应的敏感波长区间均小于120m;车体横向及竖向加速度主要受车辆荷载作用引起的桥梁变形影响,而风荷载引起的桥梁变形主要分布于主跨范围内,波长大于120m,因而未对列车车体加速度产生显著影响.

基于深度学习的列车运行环境感知关键算法研究综述

阐述深度学习在感知任务中的理论和相关基础,梳理深度学习在视觉、点云处理方面的模型架构及性能.系统总结基于图像识别的轨道区域提取、接触网异物检测和低照度图像增强等关键算法,归纳现有算法的难点.针对列车对3D感知的需求,进一步梳理面向铁路场景的点云分割、单目3D检测和多模态融合检测算法,对常见于文献的数据集进行模型性能的对比分析.总结列车运行环境感知现阶段存在的问题和未来的发展趋势.

400 km/h及以上速度下列车通过隧道时列车表面压力特征研究

[目的]为了保障400 km/h及以上速度列车穿越隧道时的行车安全,提升乘客舒适性,需采用数值模拟方法,对列车通过隧道时的列车表面压力特征进行研究。[方法]介绍了一维流动理论和广义黎曼变量特征线法,通过动模型试验对其进行了验证。探究了不同列车运行速度、不同隧道长度对8辆编组列车通过隧道时的列车表面压力影响规律,并分析了不同列车表面压力的分布特征。[结果及结论]当列车运行速度为400 km/h,隧道长度为0.7 km时,列车表面的最大正压值、最大压力幅值、最大负压值均达到峰值;当隧道长度超过0.7 km后,最大正压值基本不随隧道长度的增加而变化,最大负压值和最大压力幅值均随着隧道长度的增大而逐渐减小。在不同列车运行速度下,列车表压力值均随列车运行速度的增加而逐渐增加。列车运行速度为400 km/h时的同一列车不同部位表面的最大正压值和最大压力幅值均表现为头车>中间车>尾车,最大负压值则表现为头车<中间车<尾车。列车表面最大正压值、最大负压值和最大压力幅值在数值上均表现为随着测点距车头鼻尖的距离的增大而逐渐减小。

Spatial gust impact analysis on safety and comfort of a train crossing cable-stayed bridge combining statistical method

In order to study the safety and the comfort of high-speed trains running on a single-tower cable-stayed bridge under spatial gust,a dynamic model of wind-train-bridge analysis model is built based on the autoregressive method,the multi-body dynamics method and the finite element method.On this basis,the influence of spatial gust model loading,the suspension parameters change,wind attack angle and speed on the train-bridge system are analyzed by combining the time/frequency domain analysis and statistical methods.The results show that the spatial gust environment is one of the most important factors affecting safety and comfort and can make the calculation result tend to be conservative and more conducive.The response changes caused by K_(py),K_(px) and K_(sx) changes are nearly linear,while Ksy shows nonlinear characteristics and the most sensitivity.Wind attack angle at 75°and 90°has the greatest influence on the vehicle-bridge system.For ride comfort index,when pre-set wind speed(α=75°)reaches 20 m/s,the vertical acceleration firstly exceeds the limit value;when wind speed(α=90°)reaches 21.5 m/s,the lateral acceleration firstly exceeds the limit value,and the ride comfort of the vehicle cannot be guaranteed.For running safety index,when pre-set wind speed(α=75°)reaches 24.6 m/s,the wheel unloading coefficient firstly exceeds the limit;when pre-set wind speed(α=90°)reaches 24.5 m/s,the derailment coefficient firstly exceeds the limit,and the running safety cannot be guaranteed.The results can provide a suitable reference for the safe and stable operation of trains on the bridge.

教育强国背景下中外合作办学提升高等教育国际影响力策略研究

在加快建设教育强国进程中,中外合作办学对提升高等教育国际影响力具有重要作用,且在提升拔尖创新人才培育力、国际学生吸引力、科研学术引领力、跨境教育“中国方案”影响力等方面具备了一定基础。然而,目前我国中外合作办学尚存在结构布局不够均衡、拔尖创新人才培养质量有待提高、服务国家和地方发展能力亟须提升、高效能治理体制机制尚需完善等问题。为此,中外合作办学应加大改革创新力度,补齐短板,在适度统筹规模和效益、调整优化结构布局,加大支撑保障力度、多渠道提升人才培养质量,聚焦科技前沿和国家关切、把好引进和审批准入关,完善合作办学治理体系、探索中国特色的合作办学模式等方面持续发力,不断提高中外合作办学水平,切实提升我国高等教育国际影响力。

风屏障透风率对强风作用下重载铁路刚构-连续梁车桥耦合振动响应的影响

为探究风屏障透风率对强风作用下重载铁路刚构-连续梁车桥耦合振动的影响,先通过节段模型风洞试验获取桥上设置0%,20%,40%,60%和无风屏障5种不同透风率风屏障时车桥系统的三分力系数,再根据弹性系统动力学总势能不变原理建立风-车-桥耦合振动仿真计算分析模型,对不同车速下重载货运列车通过设置不同透风率风屏障刚构-连续梁桥开展风-车-桥系统动力学仿真计算与分析研究。结果表明:在列车上桥初期,桥梁横向位移峰值随透风率的增大而明显减小,而当列车运行趋于满布桥梁时,桥梁的横向位移峰值随透风率的增大变化不明显;列车的动力响应峰值随风屏障透风率的增大而增大,相比于满载编组列车,空载和轻重混编编组列车的动力响应对风屏障透风率的变化更加敏感。综合桥梁动力响应和列车走行安全性评价指标(脱轨系数和轮重减载率),该桥梁应设置40%透风率的风屏障。

全学段贯通式“大思政课”实践教育路径研究

实践教育是推动“大思政课”走实走深的关键着力点。全学段“大思政课”教育目标要求突出“实”的价值追求、紧扣“大”的发展趋势以及彰显“课”的本质特征。但目前,不同学段“大思政课”实践教育存在不均衡、低整合度和断点化等问题。教育主体应坚持全学段的统筹规划、一体部署和交流合作,确保“大思政课”实践教育均衡发展、有效整合且合理接续,实现“大思政课”实践教育的贯通式建设目标。

图书馆融入中外合作办学人才培养体系的实践——以山东科技大学斯威本学院为例

[目的/意义]借助中外合作办学,将国外图书馆先进的服务理念与服务方式融入国内高校图书馆,提升图书馆的服务质量,对推动高校人才培养具有重要的意义。[方法/过程]结合山东科技大学斯威本学院的中外合作办学实践,通过梳理中外合作办学的缘由,分析中外合作办学相对普通高等学校的不同办学特色,从价值理念、教学模式、空间再造及服务保障等方面具体介绍了将图书馆融入中外合作办学管理体系和教学模式所采取的变革措施。[结果/结论]扩展了图书馆服务的功能,提高了学生利用图书馆的积极性,为推动国内教育教学改革形势下的图书馆服务与管理工作的发展和完善提供参考。

基于点-弧、弧-路模型的集装箱循环班列车流组织研究

立足“公转铁”和“散改集”货源,基于集装箱运输需求的变化性和区域的不均衡性,为了实现集装箱和车辆的均衡发展、改善集装箱运输组织模式,从而充分利用铁路运输能力、提升铁路货运服务质量,围绕一种新型集装箱班列组织模式—固定车底循环班列,探讨其开行条件、班列走行径路等问题。以空车总走行距离最小为目标建立集装箱固定车底循环班列车流组织的点-弧模型,以求解循环班列的弧段选用和弧段上分配的箱流量;考虑循环班列的走行径路特点,以空车总运输成本最小为目标建立弧-路模型,以求解循环班列的走行路径和弧段上分配的箱流量。基于20英尺35 t通用箱的市场使用情况,以35 t通用箱的运单数据作为实证研究,设计搜索循环班列可行路径的算法,利用Gurobi求解器求解2种模型,分析求解结果得到了车流组织方案。对比分析2类模型在计算效率和求解结果等方面的区别,验证了模型的有效性。案例结果表明:点-弧模型求解速度快但无法直观得到走行径路和分配结果,弧-路模型对大规模网络的求解效率较低但能直接得到走行径路和分配结果,集装箱循环班列的车流组织方案可根据运输需求的空间分布和运输组织的复杂性进行调整,以提升运输效率。本研究成果能够为丰富铁路货运产品、设计循环班列组织方案提供理论方法。

我国体育院校运动项目学院办学模式:形成逻辑、现实困囿及纾解方略

运用文献资料法、逻辑分析法、历史研究法,对现阶段我国体育院校运动项目学院办学模式的形成逻辑、办学定位、生源质量、课程体系、师资力量、教学训练模式等展开综合分析。研究认为,我国体育院校运动项目学院办学模式的形成以延续体育专业人才培养模式的改良与探索为动因,以借助单项体育协会实体化改革的推动与牵拉为契机,以落实国家体育与教育政策的要求与倡议为目标。目前存在培养目标要求精度失准、课程体系支撑功能失效、师资队伍专业结构失衡、协同育人机制失全、就业出口失畅等现实困囿。对此,从战略决策、培养规格、课程支撑、师资保障、多元协同等维度,提出以区域优势为基础的项目选择和专业设置,以职业能力为追求的目标定位和要求设定,以“需求引领”“产出导向”为理念的课程体系重构,以“双师型”教师为重点的师资队伍打造,以体系建设为关键的“校政社”融合载体形成等纾困举措。