Preferred Handrail Height for Spiral Stairs—A Fitting Trial Study

Stairways are, in general, a thoroughly studied subject, but there is almost no scientific data available about spiral stairs. They are, however, widely used in homes, industrial sites and public buildings. The purpose of this study was to determine preferred handrail heights for a spiral stairway. The most preferred handrail height for descent was 105 cm. On the other hand, 95% of the participants regarded handrail heights between 95 and 100 cm satisfactory for descending. Participants’ anthropometric data was combined with the handrail height preference to develop a draft of a model to predict preferred handrail height for other user populations.     

Effects of ladder parameters on asymmetric patterns of force exertion during below-knee amputees climbing ladders

Different from walking, ladder climbing requires four-limb coordination and more energy exertion for below-knee amputees (BKAs). We hypothesized that functional deficiency of a disabled limb shall be compensated by the other three intact limbs, showing an asymmetry pattern among limbs. Hand and foot forces of six below-knee amputees and six able-bodied people were collected. Hand, foot and hand/foot sum force variances between groups (non-BKA, intact side and prosthetic side) were carefully examined. Our hypothesis was validated that there is asymmetry between prosthetic and intact side. Results further showed that the ipsilateral hand of the prosthetic leg is stronger than the hand on the intact side, compensating weakness of the prosthetic leg. Effects of ladder rung separations and ladder slant on asymmetric force distribution of BKAs were evaluated, indicating that rung separation has a more significant interactive effect on hand/foot force of BKAs than ladder slant.     

农村金融改革与发展问题展望

农村金融对农村经济社会发展具有重要的作用,随着我国农村金融机构的不断增加,涉农贷款呈现逐步增长的态势,金融产业和金融服务不断创新,农村金融的信用体系建设和支付体系建设需要进一步的改善,从根本上保证金融机构的可持续发展能力不断提升,为建设社会主义新农村创造良好的条件。针对农村金融改革过程中面临的新情况、新问题,需要采取有效的财税政策和金融政策,提升农村金融的现代化水平,通过完善机制、提升服务达到稳定农村金融市场的根本目标。     

Safety culture in railway maintenance

This paper discusses the practical problems of understanding and addressing unsafe behaviour and negative safety culture in rail maintenance. A well grounded qualitative approach informed the research methodology. Analysis of interviews with staff enabled identification of forty main factors that influence safe behaviour and safe culture. These factors ranged in proximity of their connection to the unsafe event, from those that could be found at trackside and which directly influence the behaviour of the track workers on the day (e.g. weather), to more medium term and distanced factors (e.g. supervisors’ style of management), to those at considerable distance in terms of where they emanate and can be changed, such as contradictory rules. As a result of this deep, structured qualitative enquiry, the maintenance company most concerned has disseminated findings throughout the organisation and has set a strategy to improve both safety systems and behaviour.     

Reducing fall risk by improving balance control: development, evaluation and knowledge-translation of new approaches

Problem

Falling is a leading cause of serious injury, loss of independence, and nursing-home admission in older adults. Impaired balance control is a major contributing factor.

Methods

Results from our balance-control studies have been applied in the development of new and improved interventions and assessment tools. Initiatives to facilitate knowledge-translation of this work include setting up a new network of balance clinics, a research-user network and a research-user advisory board.

Results

Our findings support the efficacy of the developed balance-training methods, balance-enhancing footwear, neuro-prosthesis, walker design, handrail-cueing system, and handrail-design recommendations in improving specific aspects of balance control.

Impact on Knowledge Users

A new balance-assessment tool has been implemented in the first new balance clinic, a new balance-enhancing insole is available through pharmacies and other commercial outlets, and handrail design recommendations have been incorporated into 10 Canadian and American building codes. Work in progress is expected to have further impact.     

单元板式轨道扣件刚度突变对行车安全性的影响分析

为研究单元板式无砟轨道扣件刚度整体及局部突变对行车安全的影响,指导扣件系统的养护维修,利用有限元方法和轮轨耦合系统动力学原理,建立车辆-轨道-路基系统垂向耦合动力学模型。研究扣件系统整体刚度突变和局部刚度突变对列车的振动特性和轮轨垂向作用力的影响规律。结果表明:扣件刚度从20 kN/mm增加到80 kN/mm时,轮对和转向架的振动加速度分别增加40.1%和28.2%,轮轨垂向力增加28.4%,车体变化不大;当局部扣件刚度突变时,车体、轮对、转向架的振动加速度和轮轨垂向力均较基本刚度(50 kN/mm)有所增大。扣件刚度整体突变以及局部突变均会对列车振动特性和轮轨垂向作用力产生不利的影响,建议及时对扣件系统进行养护检修,以保证行车的平稳性和安全性。     

Risk analysis of LPG transport by road and rail

Historical data concerning more than 130 LPG rail and road transport accidents were critically examined, identifying the scenarios, following their evolution into the final accidental events, and determining their theoretical probabilities of occurrence. In principle, rail accidents are rather hazardous, the most probable scenario being a major release followed by an UVCE. However, in order to discriminate among road and rail transport, the relevant number of trips and accident rates should be taken into account. In fact, the application, concerning the transport of 5700 ton/year of LPG in Italy along one rail and two different road itineraries, showed that the risk for rail transport was more than one order of magnitude lower than that for those on the roads. The population density along the route and the accident rate, rather than the length of the route, appear the most important factors for discriminating between different itineraries.     

Study of factors associated with risk of work-related stairway falls

This report describes a study of stairway risk factors based on video tape recordings of workers using 31 flights of stairs selected from among the industries with the highest frequency and severity rates for stair-related injuries. The video tapes were reviewed to identify all incidents, i.e., falls, trips, slips, missteps, and moments of temporary instability. The characteristics of the 98 stair users who were involved in an incident were compared to the characteristics of a matched group of stair users who did not have incidents. The factors that best discriminated between the incident group and the nonincident group were: (a) The incident group tended to be those whose movement was impeded by others and who were older; and (b) The nonincident group tended to be those who were wearing glasses and those who were very large or heavy individuals. The influence of stairway physical features on the risk of injury was examined using correlation analysis. The measure of risk was the incidence rate (observed incidents per number of observed uses) for each flight as well as for each tread. Among the several variables significantly correlated with higher incidence rate are: (a) higher effective riser height and less effective tread depth; the safest stairs have an effective riser height not greater than 7 in. (18 cm) and an effective tread depth no less than 11 in. (27 cm); and (b) for descent only (92% of the injuries), the size of the nosing projection; it appears that nosing projections that exceed $\text{11}\text{16}$ in. (1.8 cm) are associated with higher incidence rates.     

轨顶排烟口对地铁地下车站火灾排烟效果影响研究

为了研究取消轨顶风口对地铁地下车站火灾防排烟的影响，采用CFD方法，针对全封闭站台门系统和全高站台门系统2种典型地铁车站，模拟车站公共区火灾和车站列车火灾发生时，有无轨顶风口对车站内排烟效果的影响。研究结果表明:针对车站公共区火灾，无论是全封闭站台门还是全高站台门系统，取消轨顶排烟口对公共区烟气温度、可见度、CO浓度等影响较低；但针对车站列车火灾，取消轨顶排烟口对公共区烟气温度、可见度、CO浓度均具有较大影响，排烟效果下降较多。     

Effect of posture on forces and moments measured in a Hybrid III ATD lower leg

Objective: Anthropomorphic test devices (ATDs) are used to assess real injury risk to occupants of vehicles during injurious events. In the lower leg, values from load cells are compared to injury criteria developed in cadaveric studies. These criteria are typically developed with the leg in a neutral posture, whereas the ATD may assume a wide range of postures during safety evaluation tests. The degree to which the initial posture of an ATD has an effect on the measured forces and moments in the lower leg is unknown.

Methods: A Hybrid III ATD lower leg was impacted in a range of postures under conditions representing a crash test, and peak axial force and adjusted tibia index injury measures were evaluated. Ankle posture was varied in 5° increments using a custom-made footplate, and dorsi/plantarflexion (20° DF to 20° PF) and in/eversion (20° IV to 5° EV) were evaluated. Tibia angle was also varied (representing knee flexion/extension) by ±10° from neutral.

Results: Peak axial force was not affected by ankle flexion or tibia angulation. Adjusted tibia index was lowest for plantarflexion, as well as for tibia angles representative of knee extension. Both peak axial force and adjusted tibia index were lowest for postures of great inversion and were highest in neutral or near-neutral postures.

Conclusions: The range of postures tested herein spanned published injury criteria and thus would have made the difference between pass and fail in a safety evaluation. In/eversion had the largest influence on injury metrics, likely due to the change in axial stiffness and altered impact durations in these postures. Results suggest increased injury risk at neutral or near-neutral postures, whereas previous cadaveric studies have suggested that in/eversion does not influence injury risk. It is unclear whether the ATD appropriately represents the natural lower leg for impacts in out-of-position testing. Great care must be taken when initially positioning ATDs for safety evaluations, because small perturbations in posture were shown herein to have large effects on the measured injury risk using this tool.     

城市轨道交通地下线引起的环境振动影响因素研究

随着城市的发展,轨道交通在各大城市中得到迅速发展,但与之相伴的环境振动问题也日益突显.为研究城市轨道交通地下线列车运行速度、线路条件、减振措施等运营条件对环境振动影响,在某地铁线路隧道内进行了环境振动源强测试.结果表明,隧道壁源强位置处Z振级随着速度的增加而增大,列车通过速度在57～75 km/h变化时,列车速度每增加...     

列车大提速后周围流场变化诱发的事故隐患分析

选用CRH2型动车组l:l模型,对不同时速条件下列车周围流场进行模拟计算,得到列车所受空气动力随车速的变化规律,分析可能存在的安全问题.模拟结果表明:列车侧向力、升力和倾覆力矩均随着时速的增加而增大；列车快速行驶时,两侧处于负压状态,随着时速的增加负压程度也增强,垂直于列车方向压强梯度不断增大,轨道沿线两侧的行人或其它物体被卷入的可能性增加；与单列车模拟结果进行比较分析可以看出:两车交会时中间的压力非常低,列车的倾覆力矩明显增大,车体对内侧轨道的作用力也随之增大,列车运行危险性增加.     

Survival Model for Foot and Leg High Rate Axial Impact Injury Data

Objectives: Understanding how lower extremity injuries from automotive intrusion and underbody blast (UBB) differ is of key importance when determining whether automotive injury criteria can be applied to blast rate scenarios. This article provides a review of existing injury risk analyses and outlines an approach to improve injury prediction for an expanded range of loading rates. This analysis will address issues with existing injury risk functions including inaccuracies due to inertial and potential viscous resistance at higher loading rates.

Methods: This survival analysis attempts to minimize these errors by considering injury location statistics and a predictor variable selection process dependent upon failure mechanisms of bone. Distribution of foot/ankle/leg injuries induced by axial impact loading at rates characteristic of UBB as well as automotive intrusion was studied and calcaneus injuries were found to be the most common injury; thus, footplate force was chosen as the main predictor variable because of its proximity to injury location to prevent inaccuracies associated with inertial differences due to loading rate. A survival analysis was then performed with age, sex, dorsiflexion angle, and mass as covariates. This statistical analysis uses data from previous axial postmortem human surrogate (PMHS) component leg tests to provide perspectives on how proximal boundary conditions and loading rate affect injury probability in the foot/ankle/leg (n = 82).

Results: Tibia force-at-fracture proved to be up to 20% inaccurate in previous analyses because of viscous resistance and inertial effects within the data set used, suggesting that previous injury criteria are accurate only for specific rates of loading and boundary conditions. The statistical model presented in this article predicts 50% probability of injury for a plantar force of 10.2 kN for a 50th percentile male with a neutral ankle position. Force rate was found to be an insignificant covariate because of the limited range of loading rate differences within the data set; however, compensation for inertial effects caused by measuring the force-at-fracture in a location closer to expected injury location improved the model's predictive capabilities for the entire data set.

Conclusions: This study provides better injury prediction capabilities for both automotive and blast rates because of reduced sensitivity to inertial effects and tibia–fibula load sharing. Further, a framework is provided for future injury criteria generation for high rate loading scenarios. This analysis also suggests key improvements to be made to existing anthropomorphic test device (ATD) lower extremities to provide accurate injury prediction for high rate applications such as UBB.     

不同墩高下连续刚构桥抗震性能分析

以某大跨连续高墩刚构桥为依托,采用Midas/civil软件建立仿真模型,通过时程分析方法研究双肢薄壁墩参数在地震响应下对高墩连续刚构桥抗震性能的影响.以桥墩高度为主要参数,以模型阵型频率、桥墩墩顶、墩底位移及内力变化三个方面对其抗震性能进行评价.研究结果表明,随着其中一个桥墩高度的增加,桥梁频率不断减小,矮墩墩底及矮...     

基于复杂网络理论的轨道交通网络脆弱性分析

城市轨道交通是城市客运体系的重要支撑,而突发事件易使某些轨道交通站点瘫痪,从而影响轨道交通网络全局效率。分析城市交通轨道网络的拓扑特征和脆弱性对于优化路网结构、保障稳定运营有重要意义。以重庆市轨道交通网络为例,使用Space L法构建拓扑网络并用Matlab软件分析节点度、平均路径长度、聚类系数等指标和分布规律,定量计算各个站点对于蓄意攻击的脆弱性,以鉴定对网络效率影响最大的关键站点。模拟攻击实验结果表明:现阶段重庆市轨道交通网络平均路径长度较大,聚集系数较小,网络连通性有待提高。面对蓄意攻击时,红旗河沟站和大坪站作为关键节点对网络效率的影响较大。在加快重庆市轨道交通建设的同时,应在运营中加强保护关键站点。     

Lower Leg Injury Reference Values and Risk Curves from Survival Analysis for Male and Female Dummies: Meta-analysis of Postmortem Human Subject Tests

Objective: Derive lower leg injury risk functions using survival analysis and determine injury reference values (IRV) applicable to human mid-size male and small-size female anthropometries by conducting a meta-analysis of experimental data from different studies under axial impact loading to the foot–ankle–leg complex.

Methods: Specimen-specific dynamic peak force, age, total body mass, and injury data were obtained from tests conducted by applying the external load to the dorsal surface of the foot of postmortem human subject (PMHS) foot–ankle–leg preparations. Calcaneus and/or tibia injuries, alone or in combination and with/without involvement of adjacent articular complexes, were included in the injury group. Injury and noninjury tests were included. Maximum axial loads recorded by a load cell attached to the proximal end of the preparation were used. Data were analyzed by treating force as the primary variable. Age was considered as the covariate. Data were censored based on the number of tests conducted on each specimen and whether it remained intact or sustained injury; that is, right, left, and interval censoring. The best fits from different distributions were based on the Akaike information criterion; mean and plus and minus 95% confidence intervals were obtained; and normalized confidence interval sizes (quality indices) were determined at 5, 10, 25, and 50% risk levels. The normalization was based on the mean curve. Using human-equivalent age as 45 years, data were normalized and risk curves were developed for the 50th and 5th percentile human size of the dummies.

Results: Out of the available 114 tests (76 fracture and 38 no injury) from 5 groups of experiments, survival analysis was carried out using 3 groups consisting of 62 tests (35 fracture and 27 no injury). Peak forces associated with 4 specific risk levels at 25, 45, and 65 years of age are given along with probability curves (mean and plus and minus 95% confidence intervals) for PMHS and normalized data applicable to male and female dummies. Quality indices increased (less tightness-of-fit) with decreasing age and risk level for all age groups and these data are given for all chosen risk levels.

Conclusions: These PMHS-based probability distributions at different ages using information from different groups of researchers constituting the largest body of data can be used as human tolerances to lower leg injury from axial loading. Decreasing quality indices (increasing index value) at lower probabilities suggest the need for additional tests. The anthropometry-specific mid-size male and small-size female mean human risk curves along with plus and minus 95% confidence intervals from survival analysis and associated IRV data can be used as a first step in studies aimed at advancing occupant safety in automotive and other environments.     

Force-Velocity Characteristics of Individual Human Skeletal Muscles: TBCIat and TBCIong. Outline of the Method

The aim of the work is to outline a procedure of finding force-velocity (F–V) characteristics (F = f(V)) of individual skeletal muscles of the human locomotor system. The presentation is based on an example concerning extensors of the elbow joint: the lateral and long heads of triceps brachii (TBCIat and TBCIong). The experimental part of the procedure involves a natural movement of using the upper extremity to push an external object of variable, adjustable load, engaging both the elbow and shoulder joint.

Five men aged 23 took part in the experiment. Their task was to push the handle of a physical pendulum whose moment of inertia could be adjusted within the range of 58 kg m²-450 kg m², so as to give it maximum angular velocity. During each trial the movement of the trunk, of the upper extremity and of the pendulum was video recorded and the force applied with the hand to the handle of the pendulum was measured.

In order to find the F–V characteristics a simulation model SHOULDER was used, which is capable of solving the synergy problem for muscles of the arm and the shoulder girdle.

It was found that despite considerable dispersion of experimental points the respective regression lines revealed a clear tendency of decreasing muscle force for increased shortening velocity of the monoarticular head (TBCIat) and of increasing muscle force for increased lengthening velocity of the biarticular head (TBCIong) of the triceps brachii muscle.     

数值分析方法在一起高危工艺分析中的应用

以二级放热反应为研究对象,在反应体系温度、浓度均匀分布的假设基础上,根据反应速率方程和热平衡方程,建立高危工艺反应的温度和转化率随时间变化的数学模型。采用数值计算技术,以一阶差分代替微分,并结合工艺中的恒温过程、绝热过程和飞温过程,编写计算程序求得其转化率、温度在不同时间点的数值解,揭示爆炸事故的发展过程,定量分析操作参数的影响和转化率、温度随时间分布的规律。同时通过对绝热反应时间、冷凝器的冷却能力的分析,结合冷凝器的移热能力和反应放热对反应体系热积累的影响,讨论防止反应失控发生的可能性。最后探讨冷凝器热负荷余量、反应物投料浓度比等因素对控制反应失控的影响。     

Endurance time,muscular activity and the hand/arm tremor for different exertion forces of holding

This study aimed to examine the effects of exertion force on endurance time, muscular activity and hand/arm tremor during holding. Fifteen healthy young males were recruited as participants. The independent variable was exertion force (20%, 40%, 60% and 80% maximum holding capacity). The dependent variables were endurance time, muscular activity and hand/arm tremor. The results showed that endurance time decreased with exertion force while muscular activity and hand/arm tremor increased with exertion force. Hand/arm tremor increased with holding time. Endurance time of 40%, 60% and 80% maximum holding capacity was approximately 22.7%, 12.0% and 5.6% of that of 20% maximum holding capacity, respectively. The rms (root mean square) acceleration of hand/arm tremor of the final phase of holding was 2.27-, 1.33-, 1.20- and 1.73-fold of that of the initial phase of holding for 20%, 40%, 60% and 80% maximum holding capacity, respectively.     

能见度对个体疏散速度及路径选择的影响研

为提供火灾条件下人员疏散基础数据,基于4层教学楼疏散平台,开展了不同能见度环境下个体疏散实验,研究了能见度对人员疏散速度及路径选择的影响。研究结果表明:正常能见度条件下,人员的平均疏散速度为（2.37±0.23）m/s,个体间疏散速度差异明显,随着能见度降低,人员的平均疏散速度呈现均匀下降趋势,个体疏散速度最终均趋近于（0.36±0.10）m/s;人员水平疏散速度显著大于下行疏散速度,且水平疏散速度受能见度影响更大;当能见度较高时,人员以视觉作为寻路方式,倾向于选择自己最熟悉的路线进行疏散;能见度较低时,人员主要依靠触觉作为寻路方式,即借助墙或楼梯扶手进行疏散,此时人员的路径选择受到周围围挡物的共同作用。