基于尾涡强度的无人机与民机纵向安全间隔评估研究

为了解决无人机频频入侵机场净空,与民航客机发生危险接近的问题,以碰撞风险为量化指标,对无人机与民机需要保持的纵向安全间隔进行评估研究。分析民机尾涡流场对无人机运行的影响,利用Crow近场涡强度消散理论,得到实际尾迹影响区改进Reich碰撞模板,据此建立CNS/GPS性能环境下的纵向间隔评估模型,通过Matlab进行间隔值求解。研究结果表明:模型可以较为准确地反映民机起飞初始爬升阶段无人机尾随运行时导航性能和尾涡迹对所需最小间隔值的影响,并得到给定安全目标水平的计算结果。     

Motorcycle crashes potentially preventable by three crash avoidance technologies on passenger vehicles

Objective: The objective of this study was to identify and quantify the motorcycle crash population that would be potential beneficiaries of 3 crash avoidance technologies recently available on passenger vehicles.

Methods: Two-vehicle crashes between a motorcycle and a passenger vehicle that occurred in the United States during 2011–2015 were classified by type, with consideration of the functionality of 3 classes of passenger vehicle crash avoidance technologies: frontal crash prevention, lane maintenance, and blind spot detection. Results were expressed as the percentage of crashes potentially preventable by each type of technology, based on all known types of 2-vehicle crashes and based on all crashes involving motorcycles.

Results: Frontal crash prevention had the largest potential to prevent 2-vehicle motorcycle crashes with passenger vehicles. The 3 technologies in sum had the potential to prevent 10% of fatal 2-vehicle crashes and 23% of police-reported crashes. However, because 2-vehicle crashes with a passenger vehicle represent fewer than half of all motorcycle crashes, these technologies represent a potential to avoid 4% of all fatal motorcycle crashes and 10% of all police-reported motorcycle crashes.

Discussion: Refining the ability of passenger vehicle crash avoidance systems to detect motorcycles represents an opportunity to improve motorcycle safety. Expanding the capabilities of these technologies represents an even greater opportunity. However, even fully realizing these opportunities can affect only a minority of motorcycle crashes and does not change the need for other motorcycle safety countermeasures such as helmets, universal helmet laws, and antilock braking systems.     

Cycle Aware Package: Using Haddon’s matrix to reduce novice driver crashes with cyclists

Abstract

Objectives: What are we teaching drivers about safely interacting with cyclists? This is the main objective of the Cycle Aware project. As part of the study, a teaching and learning package is being developed to fill this gap in Australia.

Methods: Cycle Aware is a major national project that takes a mixed methods approach to investigate how cyclists are taught to share the road with cyclists when learning to drive. The project has five stages: (1) a national review of the driver licensing documentation; (2) interviews with key stakeholders (n?=?35) involved with novice driver education; (3) analysis of cyclist-novice driver crash data to identify the most frequent crash types; (4) develop a teaching and learning package (Cycle Aware Package), and; trial and evaluate Cycle Aware Package.

Results: Overall, drivers are taught little about sharing the road with cyclists. Representation of cyclists in government documentation is mixed and mostly negative and interviews identified driver-cyclist tensions related to attitudes and awareness of sharing the road. Crash types were similar among novice and experienced drivers. The Cycle Aware Package is being finalised and will be trialled in South Australia and Northern Territory in early 2019.

Conclusions: Cycle Aware will provide new insights into the way drivers are taught to share the road with cyclists. The Cycle Aware Package with interactive online content and driver competencies will facilitate a new approach to addressing this gap among Australia drivers.     

机械清洗法对MBR膜泥饼层的影响

膜污染是制约MBR发展的瓶颈。考察投加ABS颗粒对MBR膜组件上膜泥饼层的影响,并设对照实验。结果表明,对照MBR膜通量下降速度快,膜污染严重,膜表面上累积厚厚的泥饼层,而在ABS MBR中膜通量下降速度则缓慢的多,且膜上泥饼层积累量则明显少于对照MBR;曝气量越大,颗粒运行的速度也越快,泥饼层被撞落量也越多;颗粒以碰撞角度为45°冲刷膜的情况下,泥饼层掉落效果明显增加;泥饼层包裹的膜丝根数越多,泥饼层的静摩擦力和保持泥饼层不被破坏的力也越大,泥饼层就越难被冲刷掉。SEM照片显示,ABS MBR的膜孔堵塞要严重于对照MBR,表面的褶皱要较对照MBR多。     

The structure of the fire fighting foam surfactant Forafac®1157 and its biological and photolytic transformation products

For several decades, perfluorooctane sulfonate (PFOS) has widely been used as a fluorinated surfactant in aqueous film forming foams used as hydrocarbon fuel fire extinguishers. Due to concerns regarding its environmental persistence and toxicological effects, PFOS has recently been replaced by novel fluorinated surfactants such as Forafac®1157, developed by the DuPont company. The major component of Forafac®1157 is a 6:2 fluorotelomer sulfonamide alkylbetaine (6:2 FTAB), and a link between the trade name and the exact chemical structure is presented here to the scientific community for the first time. In the present work, the structure of the 6:2 FTAB was elucidated by ¹H, ¹³C and ¹⁹F nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. Moreover, its major metabolites from blue mussel (Mytilus edulis) and turbot (Scophthalmus maximus) and its photolytic transformation products were identified. Contrary to what has earlier been observed for PFOS, the 6:2 FTAB was extensively metabolized by blue mussel and turbot exposed to Forafac®1157. The major metabolite was a deacetylated betaine species, from which mono- and di-demethylated metabolites also were formed. Another abundant metabolite was the 6:2 fluorotelomer sulfonamide. In another experiment, Forafac®1157 was subjected to UV-light induced photolysis. The experimental conditions aimed to simulate Arctic conditions and the deacetylated species was again the primary transformation product of 6:2 FTAB. A 6:2 fluorotelomer sulfonamide was also formed along with a non-identified transformation product. The environmental presence of most of the metabolites and transformation products was qualitatively demonstrated by analysis of soil samples taken in close proximity to an airport fire training facility.     

基于AHP法的诱发露天矿作业现场碰撞事故危险点重要度排序

露天矿作业现场运行的设备碰撞事故属于安全生产重大事故,尽管发生并不频繁但是同类事故依然在生产中发生。控制诱发该类事故的危险点是现场安全管理的重点,根据现场的事故案例运用AHP法,通过对危险点排序找出其中的重要度,确定碰撞事故中的主要诱发因素,以此在动态生产中识别系统关键节点的危险性,找到预防同类碰撞事故的有效措施。由于诱发危险点在生产中的复杂性,AHP法解决的只是一段时间内的问题,但也为快速掌握安全预控问题提供了一种研究思路。这样在管理资源有限的条件下,为工艺运行的安全预防和控制提供可靠的保障。     

Improving pedestrian safety using combined HOG and Haar partial detection in mobile systems

Objective: The objective of this study is to develop a novel algorithm on a mobile system that can warn drivers about the possibility of a collision with a pedestrian. The constraints of the algorithm are near-real-time detection speed and a good detection rate.

Method: Histogram of gradients (HOG)-based detection is widely used in pedestrian safety applications; however, it has low detection speed for real-time systems. Hence, it has no direct usage for mobile systems. In order to achieve near-real-time detection speed, partial Haar transform predetections are applied to an image before HOG detection. The partial and HOG detections are merged and a score-based confidence level is defined for the final detection phase. In this way, the outcome is prioritized and different warning levels can be issued to warn the driver before a possible pedestrian collision.

Results: The proposed algorithm provides an increase in detection speed (from 46 to 76 fps) and detection rate (from 80 to 91%) with respect to HOG-based pedestrian detection. It also improves confidence of the results by multidetection merging and score assignment to detections.

Conclusions: Performance improvement of the algorithm is compared with respect to state-of-the-art detectors/algorithms. Based on the detection rate and detection speed performance, it can be concluded that the proposed algorithm is suitable to be used for mobile systems to warn drivers about the possibility of collision with a pedestrian.     

基于船舶操纵模拟的船撞桥概率研究

针对船舶在桥区水域航行过程中撞击桥墩的碰撞概率问题,建立并验证了船舶操纵数学模型,模拟了船舶在不同风、水流等条件下的航行情况,改进了AASHTO船舶撞桥概率模型中几何概率的算法,提出了以模拟试验样本的航迹带中心位置坐标为均值,以模拟实验样本结果计算的方差为方差的几何概率模型,同时引入停船概率模型。将改进后的模型应用于北江油金大桥船舶操纵模拟及船撞概率的研究,预测2020年北江油金大桥受上行船舶碰撞年频率大约2.81×10-6次/a,受下行船舶碰撞年频率3.43×10-4次/a,总碰撞频率3.461×10-4次/a。     

基于模糊层次分析法的编队内碰撞风险评价模型研究

编队内碰撞是编队飞行最大的安全威胁。为解决编队飞行灵活性与编队飞行安全的矛盾,建立了编队内各机碰撞风险评价模型指标体系,使用模糊互补判断矩阵确定了各指标的碰撞权重,实现了编队内各机碰撞的风险评估。以空军航空兵某部一架机型G与一架机型H混合双机编队为例进行了实证研究,结果表明,该模型简便易操作,可提高编队飞行训练效率。     

Assessment of patients' medical fitness to drive by primary care physicians: A cross-sectional study

Objectives: Motor vehicle collisions (MVCs) are a significant health burden in Saudi Arabia. The literature has consistently indicated that chronic medical conditions, such as diabetes, heart disease, stroke, obstructive sleep apnea, and neurodevelopmental disorders, increase the risk of MVCs. Therefore, assessment of driver fitness by primary care physicians (PCPs) remains a major health intervention that might reduce MVCs. We studied the practices of PCPs in assessing medical fitness to drive in at-risk patients.

Methods: We conducted a cross-sectional study of all 88 government-funded primary care centers in the city of Riyadh, Saudi Arabia. We administered a self-reported questionnaire to PCPs that inquired about their driving risk assessment for specific medical conditions.

Results: Among all PCPs and centers, 189 PCPs (63%) from 74 centers (84%) participated in our survey. The mean age of the PCPs was 40 ± 10 years, and 108 (57%) were men. The average clinical experience of the group was 13 ± 9 years. Fewer than half of PCPs considered diabetes mellitus (45%) and obstructive sleep apnea (46%) as potential risks for MVCs. Approximately 45% of PCPs did not notify any authority or relatives of potential driving issues that they noticed in their patients. Only 15% of the participants believed that PCPs were responsible for alerting authorities about their fitness to drive.

Conclusions: PCPs did not adequately assess their patients' driving history and eligibility. Efforts are needed to improve awareness among PCPs regarding the effects of chronic medical conditions on driving.