基于ISO 26262的车道偏离预警系统概念设计与仿真

以道路车辆功能安全规范标准ISO 26262为准则,对汽车的车道偏离预警系统（LDWS）进行了概念设计。首先分析了ISO 26262功能安全规范概念阶段的活动内容,并在此基础上,完成车道偏离预警系统的项目定义、危险分析和评估,设计了功能安全概念的相关工作,确定了功能安全等级和安全目标。最后搭建了UML仿真模型对LDWS概念设计阶段进行仿真测试,测试结果表明此设计能够满足ISO 26262规范标准,实现了车道偏离预警系统的功能安全概念设计,对车道偏离预警系统的安全开发具有指导意义。     

沙尘与大雾天气对京津石空气质量影响

采用北京、天津、石家庄2001-2010年沙尘与大雾天气的统计数据以及城市空气污染指数（API）,分析北京、天津、石家庄3市空气污染指数变化特征及大雾和沙尘天气下北京、天津、石家庄3市空气质量情况,进而得出沙尘大雾天气对京津石空气质量的影响。结果表明：2001-2010年间北京、天津、石家庄3市API总体呈下降趋势,天津、石家庄相对于北京空气质量改善较为明显,且空气质量夏季〉秋季〉春冬季。沙尘天气条件下,北京、天津、石家庄3市API平均值分别为255、179和167,空气质量出现良的比率天津为24%,北京、石家庄为10%左右,出现重污染的比率北京高达50%以上,天津和石家庄均在20%左右;3市沙尘天气高频次均出现在3-5月份,但北京沙尘天气发生次数远大于天津和石家庄。大雾天气条件下,北京、天津、石家庄3市API平均值为185、130和167,空气质量出现优或良的比率：天津〉石家庄〉北京,北京和石家庄出现重污染的比率均接近30%,天津不到10%,所以大雾天气对3市空气质量影响较小,大雾天气频次的变化波动并未对该地区空气质量的年际变化造成显著影响,3市高频次大雾天气集中在10-12月份,对该时段内空气污染呈现加重趋势有一定的贡献。所以沙尘和大雾天气均对北京、天津和石家庄空气质量存在不利影响,其中对北京影响最为严重,对天津影响最轻。整体上沙尘对3市的空气质量影响较大,大雾天气影响较小。     

低浓度二噁英抑制青鳉幼鱼耳泡生成与SOX9b相关联

2,3,7,8-四氯二苯并对二恶英(2,3,7,8-Tetrachlorodibenzo-p-Dioxin,TCDD)是一种持久性环境有机污染物质,它在有机体内的蓄积性引起研究人员的重视。以青鳉胚胎作为实验动物模型,使用原位杂交和定量聚合酶链锁反应(Polymerase Chain Reaction,PCR)技术从分子水平探讨了TCDD对胚胎耳泡的发育及其毒性作用机制。结果表明,TCDD造成青鳉幼鱼耳泡生成障碍。通过原位杂交和q PCR分析表明,TCDD引起软骨发育的变化与SOX9b表达降低有密切的关联。研究认为青鳉胚胎是一种非常敏感的TCDD模式动物,其耳泡软骨发育以及SOX9b基因表达可能是一种二恶英发育毒性的效应标记物。     

下垫面条件对流域极端事件影响及综合应对框架

在剖析下垫面条件变化对流域极端水文事件演变影响的基础上,构建了流域极端水文事件综合应对技术框架,并阐述其中的关键研究命题。结果表明,自然植被条件能够提高流域干旱之前土壤含水量并降低干旱过程中土壤蒸发速率,在一定程度上起到减缓干旱的强度和持续时间的作用;水利工程通过调节流域水资源的时空分布,增加可利用水资源量,能够缓解甚至规避流域干旱事件,但同时可能加剧坝址下游地区的干旱程度。自然植被条件将延长降水坡面产-汇流历时、降低洪峰流量,对极端降水洪涝事件具有一定的消减作用;此外,流域水土保持和修建水利工程等下垫面条件改变有利于河道行洪过程,能够起到缓解洪涝事件的作用。基于下垫面条件变化的流域极端水文事件综合应对技术框架包括旱涝事件监测、机理识别、影响评价和综合应对四个方面的内容,其中的关键研究命题主要为下垫面条件变化对流域极端水文事件影响的定量评估、面向流域极端水文事件合理的水土资源配置及其集成管理等。     

施工场地内安全标志位置的有效性研究及其应用

为提高施工场地内安全标志的可见性,选择建筑施工场地内常见的门架式出入口作为研究对象,采取理论推导与实验验证相结合的方法,探讨在观察行为中门架式安全标志的有效布置位置.首先在理论层面,从观察者的角度出发,通过研究行走路径、视野以及安全标志可见域之间的关系,推导出门架式安全标志有效布置区域的理论表示范围;然后在实验验证层面...     

基于投入产出生命周期模型的建筑业能耗及敏感性分析

建设活动消耗了大量能源,研究建筑业能耗测算方法并分析其影响因素有助于建筑业的节能减排. 采用投入产出生命周期评价模型测算建筑业能耗,分析建筑业能耗对部门间联系、部门能源强度和建筑业规模等因素变化的敏感性,提出部门对建筑业能耗的技术责任系数和结构责任系数,以判断部门在降低建筑业能耗中的责任. 结果表明,2010年我国建筑业能耗为1.07×109 t(以标准煤计);技术责任系数最大的部门是黑色金属冶炼及延压(0.489 8),其次是非金属矿物制品(0.479 8)和化工(0.211 8)等;除建筑业外,结构责任系数较大的部门包括非金属矿物制品(0.276 4)和黑色金属冶炼及延压(0.246 0)等;建筑业能耗对黑色金属冶炼及延压(0.243 8)和非金属矿物制品(0.203 4)等部门能源强度的变化最敏感. 降低建筑业能耗应注重促进高能耗建材生产节能、强化建设活动科学管理、推广高性能低能耗材料应用、提高基础设施建设水平和深化住房市场化改革等方面.      

Assessment of organochlorine pesticide contamination in waterbirds from an agricultural region,Central China

Twenty-one organochlorine pesticides (OCPs) were measured in the muscle of six predominant waterbird species from Jianghan Plain, Hubei Province, Central China. Among OCPs, DDTs were the most prevalent compounds, with average concentration ranging from 31.1 to 1445 ng/g lipid weight. Little egrets (Egretta garzetta) and Chinese pond herons (Ardeola bacchus) showed significantly higher concentrations of OCPs (p < 0.05) due to their dietary habits and migratory patterns. There were no statistically significant differences (p > 0.05) for most OCPs between sex and age groups. The accumulation profiles of HCHs and DDTs suggested that these OCPs in Jianghan Plain were largely derived from historical usage. Risk assessment indicated that heptachlor could be likely to pose adverse health effects on people consuming ducks in Jianghan Plain.     

Research progress of nitrous oxide reductase gene (nosZII) and its relationship with the environment北大核心CSCD

The greenhouse effect has become increasingly serious globally. Nitrous oxide (N2O) is both the major ozone depleting substance and a potent greenhouse gas having a global warming potential 298 times that of CO2, and the N2O concentration is still increasing at an annual rate of about 0.8 × 10-9. Nitrous oxide reductase (N2OR) can reduce N2O to N2, and until recently, the nosZ gene was the only gene known to be able to encode N2OR. Besides the well-known nosZI, a new lineage of the N2O-reductase (nosZ clade II), which is abundant and widespread in soils, has been identified. In this paper, the main characters of nosZII-containing microbial communities and the related working mechanisms are summarized. In addition to the main differences between nosZI and nosZII, the important environmental factors that regulate the composition, abundance, and expression of nosZII-containing communities are also discussed in this paper. Studies have shown that nosZII communities are distributed among a diverse range of bacterial and archaeal phyla, such as Epsilon-proteobacteria, Bacteroidetes, and Aquificae. Interestingly, most of the nosZII microbes lack a nitrite reductase encoding gene (nirS or nirK) and are therefore unable to denitrify, indicating the importance of these communities as N2O sinks. Soil properties such as texture, pH, C/ N ratio, temperature, and lake physical gradient could regulate nosZII microbe abundance and diversity, and the pH and C/ N ratio may be the most important influencing factors. Studies on the ecological function of nosZII microbes have advanced considerably with the development of molecular biology technology. However, further studies on the community structure of nosZII microbes, the influencing factors of nosZII microbe abundance and diversity, and characteristics of nosZII strains with strong N2O reducing ability are needed. We hope to provide a theoretical basis that can be used to facilitate N2O reduction and relieve the greenhouse gas problem. © 2018 Science Press. All rights reserved.     

Compliance with recommended protective actions during an H7N9 emergency: a risk perception perspective

This study investigates the factors determining an individual's response to official recommended protective measures, based on the Health Belief Model and the Protective Action Decision Model, to understand the adoption of protective behaviour during an H7N9 (Avian Influenza A) emergency. A public survey involving 1,375 respondents was conducted in Anhui Province, China, during the 2013 H7N9 outbreak to test the research model and hypotheses. The results indicate that protective, stakeholder, and risk perceptions influence positively an individual's willingness to take recommended actions. Protective and stakeholder perceptions also have a positive bearing on lay people's risk perceptions. A stakeholder perception is a vital determinant of a protective perception. More importantly, the effects of protective and stakeholder perceptions on behavioural responses to recommendations are mediated in part by risk perception. These findings can help public health officials to develop messages to encourage members of the population to protect themselves effectively during an influenza crisis.