Injury risk functions for frontal oblique collisions

Objective: The objective of this article was the construction of injury risk functions (IRFs) for front row occupants in oblique frontal crashes and a comparison to IRF of nonoblique frontal crashes from the same data set.

Method: Crashes of modern vehicles from GIDAS (German In-Depth Accident Study) were used as the basis for the construction of a logistic injury risk model. Static deformation, measured via displaced voxels on the postcrash vehicles, was used to calculate the energy dissipated in the crash. This measure of accident severity was termed objective equivalent speed (oEES) because it does not depend on the accident reconstruction and thus eliminates reconstruction biases like impact direction and vehicle model year. Imputation from property damage cases was used to describe underrepresented low-severity crashes―a known shortcoming of GIDAS. Binary logistic regression was used to relate the stimuli (oEES) to the binary outcome variable (injured or not injured).

Results: IRFs for the oblique frontal impact and nonoblique frontal impact were computed for the Maximum Abbreviated Injury Scale (MAIS) 2+ and 3+ levels for adults (18–64 years). For a given stimulus, the probability of injury for a belted driver was higher in oblique crashes than in nonoblique frontal crashes. For the 25% injury risk at MAIS 2+ level, the corresponding stimulus for oblique crashes was 40 km/h but it was 64 km/h for nonoblique frontal crashes.

Conclusions: The risk of obtaining MAIS 2+ injuries is significantly higher in oblique crashes than in nonoblique crashes. In the real world, most MAIS 2+ injuries occur in an oEES range from 30 to 60 km/h.     

城市生活垃圾综合处理前分选系统设计

本文以江油市城市生活垃圾处理厂为工程实例,介绍了垃圾前分选系统中的垃圾储料车间、行车与抓斗、垃圾上料机构、双层振动筛以及人工分选平台的工艺设计参数及设计依据,并在此基础上提出了该系统的改进建议.     

A SIMPLE HYDRAULIC SIMULATOR1

ABSTRACT: A simple simulator was constructed, calibrated, programmed and used in management studies of a hydraulic system containing two pumping stations in series, connected by canals and reservoirs. The features of the model, its calibration and use are described, and comparisons between measured and computed hydraulic behavior are presented.     

Prediction of minimum ignition energy of aerosols using flame kernel modeling combined with flame front propagation theory

Flammable aerosols have created many fire and explosion hazards in the process industry, but the flammability of aerosols has not been fully understood. The minimum ignition energy has been widely used as an indicator for flammability of combustible mixtures, but the amount of experimental data on the minimum ignition energy of aerosols is very limited. In this work, the minimum ignition energy of tetralin aerosols is predicted using an integrated model. The model applies the flame front propagation theory in aerosol systems to the growth of the flame kernel, which was created during the spark discharge in the ignition process. The aerosol minimum ignition energy was defined as the minimum level of energy in the initial flame kernel to maintain the kernel temperature above the minimum ignition temperature of 1073 K specific for tetralin aerosols during the kernel growth. The minimum ignition energy obtained in the model is influenced by the fuel-air equivalence ratio and the size of the aerosol droplets. For tetralin aerosols of 40 μm diameter, E_min decreases significantly from 0.32 mJ to 4.3 × 10 e⁻³ mJ when the equivalence ratio rises from 0.57 to 1.0. For tetralin aerosols of 0.57 equivalence ratio, E_min increases from as 0.09 mJ to 0.32 mJ when the droplet diameter rises from 10 μm to 60 μm. The trends are in agreement with previous experimental observations. The method used in current work has the potential to prediction of the minimum ignition energy of aerosol.     

以珠三角典型灰霾天气为例谈资料分析方法

分析处理复杂问题需要抓住主流,以珠三角地区发生的一次典型灰霾天气过程为例讨论了抽丝剥茧的资料分析方法.这次灰霾过程同期20日左右,中亚、蒙古国与我国北方发生了当年沙尘天气影响范围最广的一次强沙尘暴过程,冷空气前锋22日凌晨到达穗港地区,但穗港两地空气质量发生了相反的变化,香港空气质量急剧恶化,气溶胶浓度超过700μg/...     

高速冲击下多胞材料细观结构中波传播规律

目的 获取安全防护结构中细观多胞材料在高速冲击下的波传播规律.方法 采用基于3D-Voronoi细观多胞结构数值仿真和基于最小二乘法的局部应变梯度法,研究细观多胞结构在高速冲击下的冲击波波阵面传播规律.通过细观多胞结构数值仿真提取的位移场数据,结合局部应变梯度法得到界面清晰的冲击波波阵面.结果 冲击端和支撑端分别诱发右行和左行冲击波波阵面.冲击波波阵面传播过程分为3个阶段,即冲击端诱发右行冲击波阶段、支撑端诱发左行冲击波且未压缩区刚性向右运动阶段和右行冲击波压缩区域与未压缩区域一体刚性向右运动阶段.通过冲击波波速的演化规律研究,分别获取了右行和左行冲击波波阵面的拉氏位置和拉氏波速,通过严格理论推导解释了右行冲击波波阵面具有恒定减加速度的结论.最后对冲击波波阵面划分阶段的合理性进行了验证.结论 基于3D-Voronoi细观多胞结构数值仿真和基于最小二乘法的局部应变梯度法可以获取界面清晰的冲击波波阵面,细观多胞结构在高速冲击下的冲击波波阵面传播规律可为安全防护结构的设计和研究提供参考依据.     

Ankle fracture patterns in drivers are associated with femoral fracture,higher BMI,and advanced age

Objective: Despite advances in vehicle safety systems, motor vehicle crashes continue to cause ankle fractures. This study attempts to provide insight into the mechanisms of injury and to identify the at-risk population groups.

Methods: A study was made of ankle fractures patients treated at an urban level 1 trauma center following motor vehicle crashes, with a concurrent analysis of a nationally representative crash data set. The national data set focused on ankle fractures in drivers involved in frontal crashes. Statistical analysis was applied to the national data set to identify factors associated with fracture risk.

Results: Malleolar fractures occurred most frequently in the driver's right foot due to pedal interaction. The majority of complex/open fractures occurred in the left foot due to interaction with the vehicle floor. These fractures occurred in association with a femoral fracture, but their broad injury pattern suggests a range of fracture causation mechanisms. The statistical analysis indicated that the risk of fracture increased with increasing driver body mass index (BMI) and age.

Conclusions: Efforts to reduce the risk of driver ankle injury should focus on right foot and pedal interaction. The range of injury patterns identified here suggest that efforts to minimize driver ankle fracture risk will likely need to consider injury tolerances for flexion, pronation/supination, and axial loading in order to capture the full range of injury mechanisms. In the clinical environment, physicians examining drivers after a frontal crash should consider those who are older or obese or who have severe femoral injury without concurrent head injury as highly suspicious for an ankle injury.     

中国东部春季一次强冷锋活动空气污染输送过程分析

利用CMAQ(4.7.1)和HYSPLIT后向轨迹模式,结合长岛和洪泽湖站点污染物观测数据,对2011年3月31日—4月3日影响我国东北部地区的一次典型强冷锋天气空气污染过程进行模拟分析,验证表明模式能较好地模拟此次强冷锋过程. 由结果可知,此次强冷锋前后污染物浓度呈先升后降又上升的现象. 在冷锋移动过程中,锋前出现一条高浓度污染带,锋面将污染物抬升至800～500 hPa的高度,使污染物在对流层中层快速向西太平洋传输;冷锋对当地污染物的去除不仅有水平方向的推动作用,还会使污染物向高空输送. 锋面过后污染物浓度急剧降低,冷锋对长岛站点SO₂、O₃、NO_x、PM_2.5的清除率分别为90.87%、34.10%、50.56%、72.69%,对洪泽湖站点则分别为82.53%、50.45%、65.11%、36.80%. 锋面过去1~2 d后,高压控制天气形势下污染物再次开始积累、浓度回升. 冷锋前后污染物形成一个“积累—锋前抬升—高空平流输送—锋后大风清除—积累”的循环.      

初冬一次冷锋输送过程对中国东部霾天气的影响

利用常规地面气象资料、NCEP/NCAR再分析资料以及全国PM_2.5浓度数据,并结合后向轨迹、空气污染输送指数和传输通量分析,针对2019年12月10~11日一次冷锋输送造成我国中东部地区出现的大范围霾天气过程进行了分析.结果表明：（1）霾期间高空500hPa以经向环流为主,伴随着高空低压槽引导地面冷锋向东南方向移动,污染物浓度大值区也依次由华北地区移至黄淮、江淮地区.（2）冷锋过境前,华北至长江三角洲区域PM_2.5浓度均有明显增涨;北京以偏南方向的污染物输入为主,济南以西北和偏东方向输入为主,南京则主要是偏北和偏西方向的输入.（3）冷锋过境时,冷空气迅速将北京站的污染物清除;而济南站则受高压底部偏东风回流的影响,PM_2.5浓度维持在50μg/m³左右;冷锋推进至南京站时西北风已较小,对污染物的清除作用不明显.以江苏省为例,整个过程中,江苏本地污染物贡献占25.8%,江苏以外的污染物贡献占74.2%,以输送为主.（4）冷锋过境后,3站的边界层结构也略有不同,北京站的逆温层迅速被打破;济南站由于受海上暖湿平流影响,近地面由等温层变成逆温层;而南京站的近地面则由逆温层变为等温层.本研究揭示了在冷锋南下过程中,上游污染物对下游地区的影响,以及南北方站点表现出不同的污染物变化和清除特征.     

PE微塑料对土壤水分入渗的影响及入渗模型适宜性评价

为探究微塑料对土壤水分入渗过程的影响,通过室内土柱模拟试验,设置5组微塑料添加处理(0,1,2,4,6g/kg),研究了不同微塑料含量对湿润锋运移和累积入渗量的影响,并进一步评价了主要入渗模型在微塑料污染土壤中的适用性.结果表明,湿润锋运移速率随着微塑料含量的增加呈现出先减小后增加的特征,当含量达到T2时(微塑料含量2...