Development of machine learning based prediction models for hazardous properties of chemical mixtures

Lower flammability limit (LFL), upper flammability limit (UFL), auto-ignition temperature (AIT) and flash point (FP) are crucial hazardous properties for fire and explosion hazards assessment and consequence analysis. In this study, a comprehensive prediction model set was constructed by using expanded chemical mixture databases of chemical mixture hazardous properties. Machine learning based gradient boosting quantitative structure-property relationship (GB-QSPR) method is implemented for the first time to improve the model performance and prediction accuracy. The result shows that all developed models have significantly higher accuracy than other regular QSPR models, with the 5-fold cross-validation RMSE of LFL, UFL, AIT, and FP models being 1.06, 1.14, 1.08, and 1.17, respectively. All developed QSPR models can be used to estimate reliable chemical mixture hazardous properties and provide useful guidance in chemical mixture hazard assessment and consequence analysis.     

火灾发生率空间分异及影响因素研究

为了探究我国火灾空间聚集特征与影响因素的空间异质性，采用全局莫兰指数、局部莫兰指数、逐步回归模型、地理加权回归模型、地理探测器方法对我国地级市单元进行研究。研究结果表明:我国火灾发生率具有显著的聚集性；我国火灾发生率较低的“冷点”区域有1个，火灾发生率较高的“热点”区域有4个；人均GDP、城镇居民人均可支配收入、人口密度、年平均气温4 个因素的影响效应具有空间异质性。人均GDP与火灾发生率为正相关，另外3影响因素对火灾发生率的作用表现出正负2种相关关系；2因素交互作用要比单因素作用于火灾发生率时影响力更显著，各影响因素的交互作用类型有非线性增强型和双因子增强型2种。     

农地整治权属调整中农户认知对行为响应的作用机制--基于改进TPB及多群组SEM

农地整治权属调整是实现农业规模化和现代化的重要手段,而农户有效参与是推动权属调整的内在动力,研究农地整治权属调整中农户认知对其行为响应的作用机制,有助于高效引导农户参与权属调整,并为制定农地整治权属调整的政策提供科学依据。基于改进计划行为理论和湖北省11个县(市、区)1044份农户抽样调查数据,采用多群组结构方程模型探究了农地整治权属调整中不同类型农户认知对其行为响应的作用机制。结果表明:农地整治权属调整中农户行为逻辑符合改进计划行为理论,农户的行为态度、主观规范、知觉行为控制交互影响行为意愿,进而转换为行为响应,政府支持在行为意愿和行为响应之间起到部分中介作用。总体上,农户行为响应是"自发性""诱发性"和"约束性"三重行动逻辑的结合,且"自发性"占主导地位。多群组结构方程估计结果表明,纯农型与兼业Ⅰ型农户的行为响应受到"自发性""诱发性"和"约束性"三重影响,兼业Ⅱ型农户受到"自发性"和"诱发性"双重影响,非农型农户仅受到"诱发性"单一影响。因此,为引导农户积极参与农地整治权属调整,应该分别针对各类农户相应地提高其参与的"自发性"和"诱发性",降低"约束性",充分发挥农村社会经济组织的作用,将四种不同类型农户的利益需求统筹考虑,降低权属调整过程中利益协调难度。     

Before the crash: A systematic analysis of police narratives to determine the prevalence of pre-crash factors in fatality road transport crashes

Abstract

Objectives: The objectives of this study were to identify the prevalence of pre-crash factors that were present in fatal road transport crashes for the deceased and counterpart road user.

Methods: The study is a retrospective population-based case series study of transport-related deaths reported to coroners in Australia from 2013 to 2016. Data was extracted from the National Coronial Information System.

Results: In total, 6,137 fatality crashes occurred during the study period. Police reports were available for 5,523 crashes (89.9%). The most frequently reported pre-crash factors reported behaviour specifically drivers (e.g., driving without a license or while license was disqualified). Presence of intoxicating substances were also reported in the deceased and counterparts. Analyses of toxicology reports are continuing to determine if rates are comparable to level of use in community.

Conclusions: Coronial report provide detailed information that may be pertinent to understanding and potentially preventing crashes. Also emerging from the data is the extent of pre-crash factors that relate to illegal or deviant behavior and whether these are contextual or contributory factors.     

The relationship of occupational injury and use of mental health care

Introduction: Symptoms of depression and anxiety are a common consequence of occupational injury regardless of its cause and type. Nevertheless, mental health care is rarely covered by workers’ compensation systems. The aim of this study was to assess the use of mental health care post-injury. Methods: We used a subsample of patient-care workers from the Boston Hospital Workers Health Study (BHWHS). We matched one injured worker with three uninjured workers during the period of 2012–2014 based on age and job title (nurse or patient-care associate) and looked at their mental health care use pre- and post-injury using medical claims data from the employer sponsored health plan. We used logistic regression analysis to assess the likelihood of mental health care use three and six months post-injury controlling for any pre-injury visits. Analyses were repeated separately by job title. Results: There were 556 injured workers between 2012 and 2014 that were matched with three uninjured workers at the time of injury (n = 1,649). Injured workers had a higher likelihood of seeking mental health care services than their uninjured counterparts during the six months after injury (OR = 1.646, 95% CI: 1.23–2.20), but not three months post-injury (OR = 0.825, 95% CI: 0.57–1.19). Patient-care associates had a higher likelihood to seek mental health care post-injury, than nurses (OR: 2.133 vs OR: 1.556) during the six months period. Conclusions: Injured workers have a higher likelihood to experience symptoms of depression and anxiety based on their use of mental health care post-injury and use is more predominant among patient-care associates; however, our sample has a small number of patient-care associates. Practical Applications: Treating depression and anxiety as part of the workers’ compensation system has the potential of preventing further physical ailment and improving the return to work process regardless of nature of injury.     

基于改进道化学指数法的野战油库安全评估

野战油库的安全性对提高其战时生存与保障能力具有重要的作用。根据野战油库的特性,通过对道化学指数评价法进行适当改进,提出了一种新的安全评估方法,该方法通过计算野战油库战时的安全指数,从而划分出野战油库的安全等级及危险程度,对指导野战油库制定安全防护措施、提高其战时生存与保障能力具有重要的作用。     

君安矿区复垦土壤的环境质量分析与评价

以君安矿区复垦土壤为调查研究对象,分析了该矿区不同复垦基质的主要重金属污染元素Pb、Cu、Cd和Cr的含量,并采用三步评价法对该矿不同区域复垦土壤的环境质量进行了分析与评价。结果表明:君安矿西区、东区复垦土壤环境质量合格,北区、南区和中区复垦土壤均不符合我国土壤环境质量标准;通过将矿区与全国土壤背景值进行比较可知,矿区复垦土壤未受到重金属Cu的污染,受Cd、Cr的污染较轻,受Pb的污染较严重。该研究可为进一步确定矿区土壤复垦方向提供依据。     

新安江水库水环境主要问题及保护对策

新安江水库是钱塘江的重要水源,对保障钱塘江中下游的生态安全和水体功能起着举足轻重的作用。为阐明新安江水库在流域经济发展和人类活动的影响下水环境的主要问题及保护对策,促进饮用水安全保障及构建健康水域生态系统,本文对新安江水库历年的水环境指标、浮游生物群落结构及其变化及水域生态灾变事件资料进行了综合分析。目前新安江水库存在上游来水变差、局部水域藻类异常增殖、渔业生产不合理、营养程度加重等众多问题,但其突出问题是藻类生物量增长过快。新安江水库水环境保护工作要从关注水质向维持生态系统健康转变,并尽快开展生态保育工作,控制流域污染、降低藻类数量、减少藻类异常增殖影响、科学合理渔业生产是其下一步保护的关键。而关于新安江水库的研究,虽然有一定的研究基础和资料,但对水域生态系统缺乏系统认识。研究气候变化条件下新安江水库水域生态系统的结构和功能以及长期演变规律;水利调度导致水位调整对区域水动力学条件、营养物输送过程的影响及评价水利调度对水库重要环境因子和生态系统影响;渔业养殖对水环境的影响,特别是鲢、鳙鱼大水面积养殖对水库生态系统的影响应是今后新安江水库主要的研究领域和方向。     

西安表土中多环芳烃的污染特征及其来源解析

通过2008年采集西安不同功能区表层土壤样品,运用GC/MS质谱联用仪对美国EPA优控的16种多环芳烃(PAHs)进行定性、定量分析,来探讨西安表层土壤种多环芳烃的污染特征及其来源。结果表明,16种PAHs均被检出,西安表土中ΣPAHs浓度范围为125~9 057 ng/g,平均值为2 727 ng/g,主要以4~6环PAHs为主,共占总量的69%。PAHs的空间分布规律为:工业区>文教区>绿化区>郊区>农村。应用特征比值判断法可知,西安表土中PAHs主要是煤的不完全燃烧和机动车尾气排放所产生的混合源污染。借鉴国外土壤污染标准可知西安城区表土污染较为严重。     

Measurement of air exchange rates in different indoor environments using continuous CO2 sensors

A new air exchange rate (AER) monitoring method using continuous CO₂ sensors was developed and validated through both laboratory experiments and field studies. Controlled laboratory simulation tests were conducted in a 1-m³ environmental chamber at different AERs (0.1-10.0 hr^-1). AERs were determined using the decay method based on box model assumptions. Field tests were conducted in classrooms, dormitories, meeting rooms and apartments during 2-5 weekdays using CO₂ sensors coupled with data loggers. Indoor temperature, relative humidity (RH), and CO₂ concentrations were continuously monitored while outdoor parameters combined with on-site climate conditions were recorded. Statistical results indicated that good laboratory performance was achieved: duplicate precision was within 10%, and the measured AERs were 90%-120% of the real AERs. Average AERs were 1.22, 1.37, 1.10, 1.91 and 0.73 hr^-1 in dormitories, air-conditioned classrooms, classrooms with an air circulation cooling system, reading rooms, and meeting rooms, respectively. In an elderly particulate matter exposure study, all the homes had AER values ranging from 0.29 to 3.46 hr??1 in fall, and 0.12 to 1.39 hr^-1 in winter with a median AER of 1.15.