大气边界层环境影响效应的仿真试验

研究利用动力模拟与气候统计相结合的方法建立典型大气边界层环境基本要素(风速、温度、气压和密度)场仿真模型,以低空飞行器为仿真算例,在实现大气边界层环境仿真模型与飞行动力学仿真模型耦合的基础上,开展大气边界层环境影响效应的仿真试验,分析大气边界层环境对低空飞行器飞行轨迹和姿态特性的影响.通过探索大气边界层环境模型建立的可行性及其对低空飞行器影响的基本规律,为进一步开展大气环境对武器系统影响评估研究提供思路.     

测定水中动植物油含量的不确定度简化评定

对红外分光光度法测定水中动植物油的不确定度来源进行了分析,构造出合理的数学模型,确定了各输入量之间的关系,量化各分量后,合成得到满意的结果。从而提出,根据被测量及其所依赖的输入量之间的关系构造数学模型,并运用不同的评定方法对各个分量进行量化,可实现对某些检测项目不确定度的简化评定。     

供电企业岗位风险评价研究

针对供电企业,从岗位风险出发,对其进行了系统的分类,将岗位风险分为动态风险和静态风险两类,并针对每一类风险给出了具体的定义,提出了岗位风险评价切实可行的方案.     

甲烷13C同位素比值表征温度对甲烷生成途径的影响

采用测试气相碳同位素比值的方法比较了中温厌氧降解和高温厌氧降解过程中甲烷（CH₄）生成途径的差异,表征了生活垃圾厌氧消化过程CH₄生成途径的演变,并结合气液相化学组分和产甲烷菌荧光原位杂交（FISH）分析对同位素表征结果进行了验证.中温（35℃）条件下,垃圾降解初期甲烷¹³C同位素比值（δ¹³CH₄）下降至-69.5‰,表明此阶段CH₄主要产生自CO₂还原途径;随着垃圾降解进入快速产CH₄阶段,δ¹³CH₄值相应迅速上升至-23.8‰,说明乙酸发酵逐渐成为CH₄生成的主要途径,FISH实验结果也发现此阶段以乙酸发酵型产甲烷菌Methanosarcinaceae为主;当产CH₄速率逐渐减小进入稳定期时,δ¹³CH₄值迅速降低至-55‰后相对稳定,说明乙酸发酵途径的比例减小,并且维持在较稳定的水平.高温（55℃）条件下,δ¹³CH₄值始终维持在约-70‰,表明甲烷主要由CO₂还原作用生成,在快速产CH₄阶段,乙酸氧化和CO₂还原作用是CH₄生成的重要途径.     

气象灾害对天水苹果生产影响的评估技术研究

分析得出影响天水苹果正常生长的主要农业气象灾害是前秋9月大气干旱、冬季12-2月暖冬高温、苹果花期4月下旬高温干旱和春季4月下旬低温危害。各灾害发生频率在53﹪～70﹪之间,以前秋9月干旱最多,春季4月下旬低温危害最少;前秋9月大气干旱以中-大灾为主;其他灾害均以轻、中灾最多,大灾居次;各种灾害因子重灾年份最少,仅在6﹪～15﹪之间。农业气象灾害综合评估除轻灾评估准确率略低为89﹪外,中-重灾评估准确率均达100﹪,灾害评估效果比较理想,对农业防灾减灾有一定的指导意义     

岩溶石漠化地区表土孢粉与植被关系的影响因素研究——以重庆南川区南平镇为例

根据表土孢粉分析和植被样方调查,重庆南平养兔场内外5个不同方位的表土孢粉组合较好地揭示了该区孢粉组合特点及其与植被的关系。通过对该区表土孢粉组合差异性的研究,探讨了影响表土孢粉与现代植被对应关系的主要因素,即外来孢粉、孢粉产量、孢粉保存和孢粉鉴定等。运用LuoPacias孢粉鉴定系统将孢粉鉴定到种,共132种,为在这一地区开展第四纪古植被、古气候和古环境等研究提供参考性依据。     

温度对短程硝化反硝化的影响

以间歇式活性污泥法(SBR)处理生活污水,系统考察了温度变化对短程硝化反硝化稳定性和硝化反硝化速率的影响.结果表明:在较高哌温度下((28±1)℃),通过实时控制和控制污泥龄在lOd左右,可以成功实现短程硝化反硝化.在此基础上对完全亚硝酸型硝化的污泥(NO2--N/NOx--N≈1)进行降温实验,每降1℃稳定一个多月,半年后不刻意控制温度,经历了冬季lO℃的低温,成功的稳定了常温、低温短程硝化反硝化,亚硝化率始终维持在78.8%以上.实验发现降低温度后对于AOB和NOB的活性都有很大的影响,但对于AOB的影响要大于NOB,对比氨氧化速率的影响大于比反硝化速率的影响.26℃条件下的比氨氧化速率和比反硝化速率分别是10℃条件下的4.49和2.91倍.可见降低温度对于短程系统硝化反应的影响要大于反硝化的影响.     

盐城湿地沉积物环境特征及其影响因素研究

盐城沿海湿地是国家级自然保护区,正面临环境的污染和生态破坏的威胁。为了有效地保护和恢复其受损的生态功能,文章通过实地采样分析的方法研究了盐城湿地底泥氮、磷及有机物含量与分布规律及其影响因素。研究表明盐城湿地受潮流与河流水动力条件的长期综合作用,该区从陆地向海洋方向,沉积物粒度呈现由细变粗的总体变化规律。潮间带沉积物中氮、磷及有机碳在空间上也呈现出从光滩向高潮位区逐渐增加的趋势。沉积物中营养物释放与微小颗粒物的再悬浮成为潮间带水体富营养化的一个重要因素。     

Assessment of temporal stability in risk factors of crashes at horizontal curves on rural two-lane undivided highways

Introduction: Safety of horizontal curves on rural two-lane, two-way undivided roadways is not fully explored. This study investigates factors that impact injury severity of such crashes. Method: To achieve the aim of this paper, issues associated with police-reported crash data such as unobserved heterogeneity and temporal stability need to be accounted for. Hence, a mixed logit model was estimated, while heterogeneity in means and variances is investigated by considering four injury severity outcomes for drivers: severe injury, moderate injury, possible injury, and no injury. Crash data for the period between 2011 and 2016 for crashes that occurred in the state of Oregon was analyzed. Temporal stability in factors determining the injury severity was investigated by identifying three time periods through splitting crash data into 2011–2012, 2013–2014, and 2015–2016. Results: Despite some factors affecting injuries in all specified time periods, the values of the marginal effects showed relative differences. The estimation results revealed that some factors increased the risk of being involved in severe injury crashes, including head-on collisions, drunk drivers, failure to negotiate curves, older drivers, and exceeding the speed limits. Conclusions: The hypothesis that attributes of injury severity are temporally stable is rejected. For example, young drivers (30 years old and younger) and middle-aged drivers were found to be temporally instable over time. Practical applications: The findings could help transportation authorities and safety professionals to enhance the safety of horizontal curves through appropriate and effective countermeasures.     

Perceived stress,mental health,organizational factors,and self-reported risky driving behaviors among truck drivers circulating in France

Introduction: The growth of the European market for road-freight transport has recently led to important changes. The growing number of foreign pavilion drivers transiting in France, which plays a bridging role among European countries, has influenced the lives of truck drivers by increasing competition, pressure on day-to-day activities, and constraints related to delivery deadlines. Adding this new pressure to those inherent in the road-freight transport sector has raised concerns, especially ones linked to levels of perceived stress by truck drivers. Method: With safety concerns in mind, we devised a questionnaire aimed at understanding how French truck drivers and non-French truck drivers, passing through four highway rest areas in France perceive stress, organizational factors, mental health, and risky driving behaviors. A sample of 515 truck drivers took part in the survey (260 French nationals), 97.9% of whom were male. Results: The results of a structural equation model indicated that perceived stress can increase self-reported risky driving behaviors among truck drivers. Furthermore, organizational factors and mental health were closely linked to perceived stress. Finally, some differences were found between French and non-French truck drivers with respect to mind-wandering and mental health, and to perceive driving difficulties to overcome and driving skills. Practical Applications: Several recommendations based on the findings are provided to policymakers and organizations.