熔融硝盐高温分解爆炸事故后果严重度评价

为评价热处理用硝盐槽熔融硝盐高温分解爆炸事故机理和后果严重度，结合某企业铝合金件硝盐固溶热处理工艺进行研究。 利用压缩气体容器爆炸能量计算模型、超压准则和TNT当量法估算热处理用硝盐槽内熔融硝盐高温分解爆炸事故后果，得出35 000 kg熔融硝盐在高温分解转化率为50%时爆炸的TNT当量为1 257.6 kg，爆炸会造成半径53.97 m范围内的人员轻伤，该结果和利用政府推荐的危险指数法得出的外部防护距离为50 m较为接近。 以上分析计算表明:超温爆炸过程中，熔融硝盐在硝盐槽中超温分解快速产生大量气体，在硝盐槽上盖及上部硝盐的阻挡下不能及时排出，致使硝盐槽内气体压力瞬间升高，形成类似于压力容器的空间，发生物理爆炸并引发高温硝盐喷溅。     

The safety implications of vehicle seat adjustments

INTRODUCTION: The goal of this study was to gather information on the preferred front seat position of vehicle occupants and to determine the impact of variation in seat position on safety during crashes. METHOD: The study evaluated the relationship between seat position and occupant size using the chi-square test and compared the risk of severe injury for small females and large males with regard to forward and rearward seat position using logistic regression. RESULTS: While smaller drivers sat closer to the steering wheel than larger drivers, front passengers of all sizes used similar seat positions. Additionally, the risk of injury was higher for small, unbelted females in rearward seat positions and large males (belted and unbelted) in forward seat positions. CONCLUSIONS: Occupants who adjust their seats to positions that are not consistent with required federal tests are at a greater risk for severe injury in a crash.     

The Importance of Non-struck Side Occupants in Side Collisions

Current occupant protection assessment for side impact is focused on struck side occupants sitting alone. In a representative sample of tow-away side collisions from the UK, only one-third of front seat occupants in side collisions were alone, on the struck side of the car. The other two-thirds were either a non-struck side occupant alone or a situation where the adjacent seat was also occupied. In terms of restraint protection for non-struck side occupants, belts appeared to be less effective in perpendicular compared to oblique side crashes. Front seat occupancy had bearing on injury outcome. With both front seats occupied, there was a reduction in AIS 27+ injury to belted non-struck side occupants due to a reduction in chest and lower limb injuries. Struck side occupants sustained increased injury rates to the extremities when accompanied by a belted non-struck side occupant but no notable increases in moderate to serious injury to the head, chest, abdomen or pelvis.     

硬脂酸粉尘爆炸特性试验研究

为研究硬脂酸粉尘的爆炸特性,采用20 L球型爆炸仪对4个粒径范围的硬脂酸粉尘进行粉尘爆炸试验研究。结果表明:一定浓度范围内增大粉尘浓度能够提升硬脂酸粉尘的爆炸能量和燃烧速率。增大粉尘浓度,爆炸猛烈度先增强后减弱;减小粉尘粒径,能增强爆炸猛烈度和敏感度。粒径小于58 μm粉尘的爆炸猛烈度和敏感度最大,浓度500 g/m3时,该粉尘有最大爆炸压力1.12 MPa和最大升压速率142.00 MPa/s。     

瓦斯涌出严重程度分形预测研究

为了研究瓦斯涌出严重程度与地质构造之间的定量关系,以某矿井田为例,采用分形几何学手段研究了井田地质构造的分形特征,并将构造分维数与瓦斯涌出严重程度作了对比分析。其结果表明:所研究矿井田地质构造具有分形特征,构造分维数能够定量地描述地质构造的复杂程度,构造分维数与瓦斯涌出严重程度之间存在正相关关系,分维值大于1.3的区域是有可能发生瓦斯异常涌出的区域。该研究成果对于高瓦斯矿井进行瓦斯区域预测研究具有重要的理论和实用价值。     

甘肃黄土高原气象旱度模式研究

干旱是限制甘肃黄土高原农业可持续发展最主要的自然灾害之一，研究适合该区的干旱指标，是进行有效干旱监测的基础。为了制定出考虑因素较全面、具有时空可比性的适合甘肃黄土高原情况的干旱指标，依据帕默尔旱度模式的基本原理和方法，针对甘肃黄土高原的实际情况，从建模资料长度、站点密度、可能蒸散计算、土壤田间持水量和径流计算等几个方面对原有模式进行了修正，用甘肃黄土高原12个代表站的资料，建立了旱度模式，并确定了权重因子。在此基础上，计算了20个代表站点的气象旱度值，并与实际旱情记载进行了对照检验。结果表明，用该模式计算的旱度值与实际灾情吻合得较好，能够反映出该区干旱程度的变化情况，特别是对一些重大旱段。通过修正后的甘肃黄土高原的气象旱度模式与原美国帕默尔旱度模式和中国1985年修正的帕默尔旱度模式的比较，进一步说明该模式适合应用于干旱评估和监测业务。     

Analysis of driver injury severity levels at multiple locations using ordered probit models

Problem: The occurrence and outcome of traffic crashes have long been recognized as complex events involving interactions between many factors, including the roadway, driver, traffic characteristics, and the environment. This study is concerned with the outcome of the crash. Method: Driver injury severity levels are analyzed using the ordered probit modeling methodology. Models were developed for roadway sections, signalized intersections, and toll plazas in Central Florida. All models showed the significance of driver's age, gender, seat belt use, point of impact, speed, and vehicle type on the injury severity level. Other variables were found significant only in specific cases. Results: A driver's violation was significant in the case of signalized intersections. Alcohol, lighting conditions, and the existence of a horizontal curve affected the likelihood of injuries in the roadway sections' model. A variable specific to toll plazas, vehicles equipped with Electronic Toll Collection (ETC), had a positive effect on the probability of higher injury severity at toll plazas. Other variables that entered into some of the models were weather condition, area type, and some interaction factors. This study illustrates the similarities and the differences in the factors that affect injury severity between different locations.     

矿山重大危险源评价及瓦斯爆炸事故伤害模型建立的若干研究

基于危险源评价的基本原理 ,结合系统论的观点与矿山重大危险源的实际 ,确立了矿山重大危险源伤害模型的合理假设和简化 ,并在此基础上 ,首次提出了从危险源系统事故的伤害模型来研究矿山矿井瓦斯爆炸事故的严重度方法 ;并结合矿井瓦斯爆炸事故的实际 ,建立了瓦斯爆炸事故冲击波的伤害模型。使得目前人们通常认为无法对矿井瓦斯爆炸事故严重度研究进行建模成为可能 ,这无疑是对矿山重大危险源评价工作和瓦斯爆炸事故研究的一次重大创新和完善     

MULTIYEAR DROUGHT SIMULATION1

ABSTRACT: Previous studies on multiyear droughts have often been limited to the analysis of historic annual flow series. A major disadvantage in this approach can be described as the unavailability of long historic flow records needed to obtain a significant number of drought events for the analysis. To overcome this difficulty, the present study proposes to use synthetically generated annual flow series. A methodology is presented to model annual flows based on an analysis of the harmonic and stochastic properties of the observed flows. Once the model is determined, it can be utilized to generate a flow series of desired length so as to include many hydrologic cycles within the process. The key parameter for a successful drought study is the truncation level used to distinguish low flows from high flows. In this paper, a concept of selecting the truncation level is also presented. The drought simulation procedure is illustrated by a case study of the Pequest watershed in New Jersey. For the above watershed, multiyear droughts were derived from both historic and generated flow series. Three important drought parameters, namely, the duration, severity, and magnitude, were determined for each drought event, and their probability distributions were studied. It was found that gamma and log normal probaility functions produce the best fit for the duration and severity, respectively. The derived probability curves from generated flows can be reliably used to predict the longest drought duration and the largest drought severity within a given return period.     

Analyzing pedestrian crash injury severity under different weather conditions

Objective: Pedestrians are the most vulnerable road users due to the lack of mass, speed, and protection compared to other types of road users. Adverse weather conditions may reduce road friction and visibility and thus increase crash risk. There is limited evidence and considerable discrepancy with regard to impacts of weather conditions on injury severity in the literature. This article investigated factors affecting pedestrian injury severity level under different weather conditions based on a publicly available accident database in Great Britain.

Method: Accident data from Great Britain that are publicly available through the STATS19 database were analyzed. Factors associated with pedestrian, driver, and environment were investigated using a novel approach that combines a classification and regression tree with random forest approach.

Results: Significant severity predictors under fine weather conditions from the models included speed limits, pedestrian age, light conditions, and vehicle maneuver. Under adverse weather conditions, the significant predictors were pedestrian age, vehicle maneuver, and speed limit.

Conclusions: Elderly pedestrians are associated with higher pedestrian injury severities. Higher speed limits increase pedestrian injury severity. Based on the research findings, recommendations are provided to improve pedestrian safety.