Numerical simulation and experimental research of surrounding rock deformation of floor roadway under short-distance coal seam group combined mining

According to the influence of the combination of short-distance coal seam group on mining roadway, using numerical simulation software FLAG2D to draw the abutment pressure distribution ahead the working face and the area of influence in fully-mechanized mining conditions, the variation rules of surrounding rock supporting pressure of floor roadway and the deformation rules were summarized. GYS-300 anchor dynamometer was used to measure the roadway surface displacement, and the conclusions of numerical simulation were verified.

Exploring switch tendency between cyclists and non-cyclists using market segmentation approach

This work aimed to explore the switch tendency of bicycle use between cyclists and non-cyclists.The attitude based market segmentation approach was proposed to achieve the research objective.The filed investigations were conducted in Nanjing,China,to obtain travelers' actions and attitudes towards bicycle uses.The structural equation modeling(SEM) was used to identify the attitudinal factors indicating variables and to explore the interrelationships among them.The SEMs were developed separately for the cyclist group and the non-cyclist group.All respondents were clustered into eight distinct segments by six selected attitudinal factors.The mode switch tendency and attitude in each segment is different from others,indicating that different segments have particular policies or strategies to encourage cycling.Policy implications that best serve the potential bicycle users were discussed to reduce the number of cyclists who have high tendency to use other modes,and increase the possibility of using bicycle in the non-cyclists group with the moderate and high switch tendency.

Design of Facial Impact Protection Gear for Cyclists

The concept of facial impact protection mask for cyclists is proposed in response to increased participation in cycling and the need for injury prevention. The research aims to develop an approach for design of facial impact protection gear to reduce the risk of severe injury. Impact test equipment and procedure, face surrogate and protection material performance criteria are developed. Three groups of protective materials – rigid crushable, semi rigid, and soft cushion foams are tested and assessed according to criteria. The criteria are linked to measures of the risk of facial and brain injuries: HIC (Head Injury Criterion), peak deceleration, Face-bone damage and energy absorption. The impact energy is simulated by a drop test using a 48 mm-radius-steel hemispherical impactor, with a weight of 4.63 kg similar to that of headform J specified in AS/NZS standard. The drop-height is 1500 mm, and the linear deceleration force of the impactor is recorded and used to establish the performance of the materials. The HIC is used to predict the risk of brain injury, whereas the developed face surrogate is used to assess facial bone injury. A 5.4 m/s facial impact to the unprotected-face of a cyclist can result in the risk of severe facial bone fracture and mild brain injury. The impact test results for rigid foam protection of 40 mm thickness shows no densification (bottom out) and absorbs the impact energy without damage to the Foam-bone of the face surrogate. At 20 mm thickness, rigid polyurethane foams performed best with Foam-bone damage ranging from 15.1% to 20.5%. Other materials with thicknesses of 20 to 28 mm showed Foam-bone damage between 21.8% and 35.1%. The HIC values ranged from 267 to 522, with memory foams and expanded polystyrene foam having the lowest values. Peak deceleration ranged from 71 g to 105 g for the materials tested. It is concluded that the impact energy can be dissipated by the protection material thereby reducing the risk of severe facial injury to the protected area.

Short-Distance Low-Power Wireless Access System

The short-distance low-power technologies for wireless access communications, including Bluetooth, Ultra-Wideband (UWB) and Wireless Fidelity (Wi-Fi), focus on the physical layer and Medium Access Control (MAC) layer. Bluetooth is a wireless protocol for exchanging data over short distances. It is an alternative to RS232 data cables. UWB is a radio technology that can be used at very low energy levels for short range. It provides flexible high-bandwidth wireless access. Wi-Fi enables the wireless connection of fast-access devices and mobile devices in Wireless Local Access Network (WLAN) and it is suitable for long distances. The standardizations of the above technologies have been developed and published soon after the emergence of these technologies. Among all the standards, Bluetooth and Wi-Fi are the most important ones.

交通弱势出行者轨迹预测及安全管控策略

针对骑车人在交通事故中易受伤害的问题,提出一种基于骑车人意图识别的轨迹预测方法.首先,从骑车人角度及车辆角度提取骑车人的多元特征,如运动方向、回头概率、与车辆相对位置等,在十字路口场景下构建动态贝叶斯模型网络,分析了骑车人意图的影响因素,最终得到骑车人意图后验概率.其次,根据意图识别结果,构建了相关交通场景并给出了骑车人运动方程,通过基于粒子滤波方法的骑车人轨迹预测算法,结合运动方程及观测方程,以粒子模拟骑车人未来轨迹集.最后,搭建激光雷达和单目相机为主的数据采集硬件平台,获取与骑车人运动及姿态有关的信息,根据收集的7 358帧数据,计算出骑车人进入十字路口区域的时长,用以对算法进行评价.结果表明:本算法在骑车人过街前0.24~0.54 s可基本识别骑车人的意图,能够预测骑车人未来5.0 s内的轨迹集;算法具有较好的实用性,可以降低骑车人与车辆碰撞事故的发生概率.

考虑自行车骑行者PM_(2.5)吸入量的健康骑行速度识别方法

为降低空气污染时自行车骑行者的PM_(2.5)吸入量,提升健康水平,其可采用减小行程暴露时间或呼吸速率2种方式。2种方式对骑行速度的要求相反,且PM_(2.5)等污染物的吸入量因人而异,所以亟需建立考虑个体差异的PM_(2.5)吸入量-骑行速度模型,以识别骑行者在PM_(2.5)吸入量最小时的健康骑行速度。能量消耗模型以心率和个体特征指标为变量计算空气吸入量,并可结合PM_(2.5)暴露质量浓度和骑行时间进而计算骑行者出行过程的PM_(2.5)吸入量。根据个体骑行者的速度与心率的关联特征构建PM_(2.5)吸入量-骑行速度模型,并通过求导方法获得健康骑行速度。对西安市173名被试试验结果的分析表明:健康骑行速度下男性、女性的PM_(2.5)吸入量与最小和最大骑行速度下的PM_(2.5)吸入量相比,降低比例分别为17.06%、8.57%和1.85%、2.50%。PM_(2.5)吸入量和骑行速度之间呈“U”形曲线分布,“U”形曲线最低点对应于PM_(2.5)吸入量最小时的健康骑行速度。男性健康骑行速度与年龄、体重和基础心率各变量间的相关关系均呈正相关,而女性健康骑行速度与年龄、体重和基础心率各变量间的相关关系分别呈正相关、负相关和正相关。健康骑行速度分布结果可为骑行者针对个体差异性特征提供参考,并建立污染天气下骑行者PM_(2.5)吸入量减少的交通管控方法,提升居民在骑行过程中的健康水平。

蒙特卡罗方法模拟公路自行车运动员的功率及速度分布

近些年来,公路自行车赛引起众多关注,如何使运动员在比赛中获得更好的成绩成为众多研究的目标。为给出自行车运动员在比赛过程中功率分配方案,本文首先建立了公路自行车赛车手的功率曲线模型,然后分析对比了不同赛车选手的特点;再通过分析赛车手的在不同性质路段的动力学模型,获得运动员经过具体赛段的时间和速度随功率的变化。我们运用蒙特卡罗方法得到了不同赛车手在不同路段最佳的功率和速度分配曲线,并将模型应用于2021公路自行车UCI世锦赛,得到不同类型运动员具体功率和速度曲线在路程中的分布。通过这一模型我们可以得知,赛车手在赛程中尽力保持匀速状态并在擅长的路段进行一定的加速可以得到最佳的比赛结果。最后我们分析了该方法得到的结果的稳定性。

快速伸缩复合训练对青少年公路自行车运动员下肢爆发力的影响

通过对16名专业运动员进行了为期10周的实验,旨在探究快速伸缩复合训练对青少年公路自行车运动员下肢爆发力的影响。实验设计包括实验组和对照组,分别接受快速伸缩复合训练和传统力量训练。通过多种测试指标,如1RM杠铃深蹲、自由纵跳、立定跳远、30米跑以及Wattbike功率自行车测试,全面评估了运动员的下肢爆发力。实验结果显示,接受快速伸缩复合训练的实验组在各项测试指标上均取得显著进步,且提升幅度明显优于对照组。这一研究为青少年公路自行车运动员的训练提供了新的策略和方法,证实了快速伸缩复合训练在增强下肢爆发力方面的有效性。

Analysis of bicyclist-vehicle crash at intersection area considering behavior prior to crash:A random parameter ordinal probit approach

In order to analyze the risky factors that affect vehicle-cyclist crash injury severity at the intersection area,especially the factors relating to the road users behaviors,an empirical study was conducted by collecting accident records from 2011 to 2015 from the General Estimates System.After preliminary screening,the variables were classified into 5 main categories including cyclists characteristic and behavior,drivers characteristic and behavior,vehicle characteristic,intersection condition,and time.The random parameter ordinal probit(RPOP)was used to study the significant influencing factors and corresponding heterogeneity.The results show that failing to obey traffic signals,failing to yield to right-of-way,dash and drinking before cycling can increase the injury severity for cyclists,and the corresponding fatal injury likelihoods increase by 53.2%,40.0%,86.3%,and 211.5%,respectively.Moreover,drivers inattention,speeding,going straight and left turning increase the risk of crashing for cyclists.The corresponding fatal injury likelihoods increase by 134.5%,186.5%,69.3%,and 22.7%,respectively.Other indicators such as age,gender,vehicle type,traffic signal and intersection type can also affect injury severity.

Study on the relationship between knee injury recovery and traditional Chinese medicine constitution of young male amateur cyclist in Hainan island cycling league

Objective:To study the relationship between the recovery of knee joint injury and traditional Chinese medicine constitution of young male amateur cyclist in Hainan.Methods:720 young male amateur cyclists were selected from the tour nanli lake national wetland park cycling race and Hainan international tourism island cycling league(ding'an station)in 2019.According to the classification criteria of TCM constitutions in classification and determination of TCM constitutions revised by the Chinese association of traditional Chinese medicine in April 2009,the TCM constitutions were divided into mild constitution group and Yin deficiency constitution group.Standard Kujala knee pain questionnaire was used to evaluate knee joint function in pinyin and Yin deficiency groups.To observe the relationship between TCM constitution and functional injury and recovery degree of knee joint.Results:Body mass index(BMI)of Yin deficiency quality was lower than that of pinyin deficiency quality(P<0.01).Score of knee flexion and extension degree was higher in Yin deficiency quality 30 minutes before the race(P<0.05).The score of Yin deficiency quality was lower after 30 minutes of squatting(P<0.01)and jumping(P<0.05).The total score of knee joint was higher 5 days after the race(P<0.01).The knee flexion and extension(P<0.05)and jump(P<0.05)were higher in the pre-race and post-race scores.Conclusion:There is a high correlation between the constitution of traditional Chinese medicine and the degree of functional injury and recovery of knee joint.The degree of post-game sports injury is higher and the recovery of post-game sports injury is faster.Therefore,different sports protection schemes can be formulated for different constitutions in bicycle RACES to reduce the occurrence of sports injuries and accelerate the recovery time of sports injuries.

考虑多身体部位的二轮车骑行者事故伤害严重程度研究

现有针对二轮车事故后果的研究主要侧重于讨论骑行者总体伤害,少有针对骑行者具体身体部位的受伤情况相关研究。为揭示各身体部位受伤之间的关联性及致因,基于中国深度事故数据(CIDAS)中2799起二轮车事故,以二轮车骑行者头部、胸部、上下肢等7个主要部位伤害严重程度为因变量,选取44个主要自变量以表征碰撞前行为、碰撞位置等信息。采用带随机参数的多变量模型进行研究,以更好解释各受伤部位严重程度间的关系及数据中未能观测到的异质性。结果表明:二轮车骑行者性别及年龄、车辆属性、碰撞前二轮车驾驶行为及二轮车被撞位置均会对二轮车骑行者不同部位的伤害造成显著影响;头部、胸部及下肢在二轮车事故中是最脆弱的3个部位,值得进一步研究;中年二轮车骑行者在头部伤害模型服从正态分布的随机参数,即中年二轮车骑行者会对二轮车骑行者头部伤害严重程度存在异质性影响;加强汽车及二轮车的安全设计从而保护二轮车骑行者胸部和腹部极有必要;佩戴头盔不仅能够保护头部伤害,对于保护上肢伤害也有重要作用。

车辆和自行车碰撞事故中骑车人下肢损伤风险研究

研究车辆与自行车碰撞事故中骑车人的下肢损伤风险,并确定车辆碰撞速度、自行车速度和骑车人特征等参数对骑车人下肢严重损伤的影响。为此,从德国深入事故数据库(German in-depth accident study,GIDAS)中挑选出471个带有骑车人下肢损伤的案例,并对其进行描述性统计和成组独立样本T检验,使用逻辑回归方法建立自行车骑车人下肢严重损伤风险函数模型,分析车辆碰撞速度、自行车速度和骑车人特征(年龄、身高和体重)对骑车人下肢严重损伤风险的影响。结果表明:车辆碰撞速度、骑车人年龄和体重是影响骑车人下肢严重损伤的显著性因素,其中车辆碰撞速度影响最为显著,其次是年龄和体重,且骑车人的下肢严重损伤风险与车辆碰撞速度、骑车人年龄和体重呈正相关。当汽车碰撞速度为55 km/h时,骑车人下肢严重损伤风险几率为50%。

功率车Tabata间歇训练在场地自行车赛前训练中应用的个案研究

目的:比较场地世界杯赛前阶段,两名自行车运动员(郭×、顾×)分别应用“减量增强度”和“训练量不变”两种功率车Tabata间歇训练方案的训练课中运动表现和生理机能适应的差异。方法:场地短距离自行车运动员郭×和顾×3周完成7节功率车Tabata间歇训练(TIET)课,每节课包括4组内容为次数不同的“120 r/min稳定踏频骑20 s+60 r/min放松恢复骑10 s”训练。郭×单节课总骑行次数逐步减少、总传动距离逐步增加,而顾×常规训练课总次数不变。采集训练课中的骑行功率、做功、心率及每组骑行后的血乳酸进行分析。结果:郭×单节课总做功从第1节课的266.8 kJ逐渐降低至第7节课的201.0 kJ,但单节课的平均功率出现逐课次增加的变化趋势。郭×仅第2节课的平均心率较第1节课下降6.1%,接下来5节课明显回升;郭×第6和第7节课后的血乳酸清除量(ΔBLa)分别显著升高至1.05 mmol/L和1.3 mmol/L。结论:在场地自行车赛前阶段完成的7节功率车Tabata训练课中,通过减少训练课骑行次数、增大阻力档位,可在提高训练强度的同时,降低训练量以促进体能恢复,完成“减量增强度”的赛前训练目标。

公路自行车运动员功能性动作筛查结果及纠正训练效果分析

选取18名辽宁省公路自行车运动员为研究对象,首先进行FMS测试,根据测试结果设计功能性动作纠正训练方法,最后分析8周纠正训练后运动员FMS测试结果变化情况,旨在为公路自行车运动员预防运动损伤和改善运动表现提供参考。结果显示:公路自行车运动员在纠正训练前FMS总分低于14分,存在损伤高风险;其中深蹲、肩部灵活性和躯干旋转稳定性三项测试得分偏低,躯干稳定俯卧撑得分最高。主要存在问题为踝关节背屈灵活性不足,下肢后侧肌肉紧张伸展性差,肩部灵活性差,多个维度上整体核心区域的稳定性控制能力和身体协调性一般。针对公路自行车运动员FMS测试结果制定功能性纠正训练方案,纠正训练干预后,公路自行车运动员FMS总分有显著提高,且得分高于14分,损伤风险降低;有效提高了运动员的灵活性、稳定性和神经肌肉控制能力,改善了运动员的动作质量,降低了运动损伤的风险。

负重振动训练对公路自行车运动员下肢力量影响的研究

目的:探讨为期6周的负重振动训练对公路自行车运动员下肢力量的影响。方法:选取20名男子公路自行车运动员并随机分为对照组和实验组,每组10人。对照组进行常规负重力量训练,实验组采用负重振动训练,训练共持续6周,每周3次,每次60min。分别在实验前后对所有运动员进行下肢等速肌力和下蹲跳(CMJ)测试,分析比较实验前后两组运动员下肢力量的提高情况。结果:对照组和实验组运动员等速肌力和CMJ测试在实验前均无显著性差异(P>0.05);经过6周的不同训练干预,在等速肌力测试60°/s时,接受负重振动训练的实验组公路自行车运动员髋关节、膝关节屈肌群和伸肌群峰值力矩以及踝关节的跖屈和背屈肌群峰值力矩均有显著提高(P<0.05),并且显著优于采用传统负重训练的对照组运动员(P<0.05);在180°/s等速肌力测试时,实验组运动员髋关节、膝关节的屈肌群和伸肌群峰值力矩显著提高(P<0.05),且与对照组相比差异显著(P<0.05),实验组踝关节的跖屈和背屈肌群峰值力矩提高不显著(P>0.05),与对照组相比差异也不显著(P>0.05),但提高幅度要高于对照组。实验组运动员负重振动训练后CMJ成绩有了显著提高(P<0.05),并且显著高于对照组运动员(P<0.05)。结论:6周的负重振动训练能够有效提高公路自行车运动员的下肢最大力量、快速力量和爆发力,并且训练效果要优于传统负重力量训练。

优秀短距离自行车运动员无氧代谢能力特征研究

目的:比较不同性别和训练水平运动员无氧能力的差异,探讨短距离自行车运动员高能磷酸原供能、糖酵解供能和混合无氧供能能力的特征。方法:对16名优秀短距离自行车运动员进行10s(女)、15s(男)、30s和60s的无氧功测定,测定运动后即刻、运动后3min恢复心率和血乳酸。结果:1)磷酸原代谢能力表现出明显的性别差异,男运动员最大功率、相对最大功率、平均功率、相对平均功率、最大圈数都明显高于女运动员;2)30s和60s两种测试中,运动员爆发力表现出相同水平,但糖酵解代谢持续供能能力随运动时间的延长而明显下降;3)男子优秀运动员组15s无氧功最大功率、平均功率明显高于普通组。男、女最大圈数大于普通组,达到最大圈数时间小于或等于普通组;4)男子优秀组运动员30s、60s平均功率高于普通运动员组。女子优秀运动员组30s、60s平均功率、最大圈数明显高于普通运动员组,60s最大功率明显高于普通运动员组(P<0.05)。结论:1)优秀短距离自行车运动员具有较强的磷酸原代谢能力,男运动员明显强于女运动员;2)较强的糖酵解代谢能力是短距离自行车运动员无氧代谢能力的特征;3)评定磷酸原系统能力时,男、女运动员都使用10s无氧功测试为好;4)不同水平运动员的无氧代谢能力表现出明显差异,优秀运动员组强于普通运动员组。

优秀自行车运动员不同训练手段后血乳酸的评定

夏训测验周内,对上海自行车队男子团体竞速5名优秀运动员,以三种典型的训练手段训练后血乳酸的变化进行了测定,结合测验成绩,评价训练手段的作用和效果,评定上海队男子团体各队员的训练水平与运动能力,为教练员进行针对性训练提供客观依据和建议。

5周高原训练对优秀自行车运动员WBC、RBC、HGB和HCT影响的研究

通过对山东省8名优秀自行车运动员5周高原训练前、训练中与训练后与免疫能力和有氧运动能力相关指标变化规律的分析,研究高原训练对优秀自行车运动员免疫能力以及有氧运动能力的影响。8名研究对象在高原进行为期5周的训练,3天一周期,与平原训练内容一致。运动员WBC水平在上高原后第1周末开始减少,持续3周呈现出显著性差异(P<0.05)后上升,在下高原后的第1周达到一个峰值,并与进高原前呈现显著性差异(P<0.01),随后又下降趋于稳定;RBC、HGB和HCT三个指标变化趋势基本一致,都是在进入高原后升高,到第4、5周达到峰值后趋于稳定,呈现出和高原前比较显著性差异(P<0.05或P<0.01);高原训练结束后下降,直到低于高原训练前水平后回归,第5周左右达到高原训练前水平。经过5周的高原训练,可以观察到运动员的血液指标变化大致呈现3个时相的变化,即升高相、保持相、回归相,提示高原训练导致运动员免疫能力产生明显变化,与运动能力有关的指标显著升高,并持续到下高原后两周左右。高原训练要严格运动员机体监控,在下高原两周内参加比赛更有利于运动员成绩的发挥。

3种自行车功率计无氧功率测试结果的比较

采用 Monark 834,Monark 839E,SRM3种自行车功率计对8名优秀男子自行车运动员进行30s Wingate 元氧功率测试(WAT),对测试结果进行比较,分析3种功率计测定参数的异同与自行车实际运动方式的差异。结果表明:Monark834进行 Wingate 测试和自行车运动实践不尽相符。Monark 839E 可以比较精确的反映受试者的起动能力。Monark 834和 Monark839E 进行 WAT 测试时,其预定负荷受到一定的限制。SRM 测试指标的内容和精度较Monark834、Monark 839E要高。从模拟自行车运动实际状况来看,SRM 是更适合自行车运动员测试的专业工具。

优秀男子短距离自行车运动员有氧代谢能力特征

对8名优秀男子短距离自行车运动员递增负荷运动过程中各时段气体代谢、生理、生化指标的动态变化情况进行测定分析,了解优秀短距离自行车运动员的有氧代谢能力的水平与特征。结果发现：1．递增负荷运动中,短距离自行车运动员乳酸强度曲线拐点较低,但斜率较大,表现出无氧供能系统动员速度快的特点。2．不同距离主项对运动员有氧代谢能力需求存在差异。3．有氧代谢能力的优劣并不是影响专项成绩的主要因素。