气相色谱法测定有机磷农药残留的常见问题探讨

针对气相色谱法测定有机磷农药残留过程中常见的基线噪声大、活性位点吸附、热分解和基质效应等4个问题,从气相色谱仪的结构和有机磷农药的性质出发,探讨了解决办法。提出从气路故障、检测器、外部干扰等3个方面排查,降低基线噪声;正确使用玻璃衬管和色谱柱,消除活性位点;合理设置进样口和检测器温度,防止发生热分解现象;采用基质净化、基质匹配校准及加入分析保护剂的方法,避免基质效应。     

紫外光度法测定硝酸盐氮有关问题的探讨

试验了水样预处理过程中所加氢氧化铝悬浮液的数量,以加１ｍｌ,并作了以活性炭代替树酯的试验,结果表明对测定结果的精密度和准确度均无影响。简化了操作手续,节省了时间。     

The role of off-path glances: A quantitative analysis of rear-end conflicts involving Chinese professional truck drivers as the striking partners

Introduction: Rear-end crashes are one of the most frequent crash types in China, leading to significant economic and societal losses. The development of active safety systems – such as Automatic Emergency Braking System (AEBS) – could avoid or mitigate the consequences of these crashes in Chinese traffic situations. However, a clear understanding of the crash causation mechanisms is necessary for the design of these systems. Method: Manually coded variables were extracted from a naturalistic driving study conducted with commercial vehicles in Shanghai. Quantitative analyses of rear-end crashes and near crashes (CNC) were conducted to assess the prevalence, duration, and location of drivers’ off-path glances, the influence of lead vehicle brake lights on drivers’ last off-path glance, and driver brake onset, and the influence of off-path glances and kinematic criticality on drivers’ response to conflicts. Results: The results indicate that the Chinese truck drivers in our study rarely engage in distracting activities involving a phone or other handheld objects while driving. Instead, they direct their off-path glances mainly toward the mirrors, and the duration of off-path glances leading to critical situations are shorter compared to earlier analyses performed in Western countries. The drivers also often keep small margins. Conclusions: Overall, the combination of short time headway with off-path glances directed toward the mirror originates visual mismatches which, associated to a rapid change in the kinematic situation, cause the occurrence of rear-end CNC. When drivers look back toward the road after an off-path glance, a fast response seems to be triggered by lower values of looming compared to previous studies, possibly because of the short time headways. Practical Application: The results have practical implications for the development of driver models, for the design of active safety systems and automated driving, and for the design of campaigns promoting safe driving.     

车船用内燃发动机噪声污染及其控制

分析内燃机的噪声源和传统的无源降噪方法，结合作者的研究工作介绍了一种随计算机技术和现代控制理论发展起来的主动消声新技术一有源降噪。     

AEB effectiveness evaluation based on car-to-cyclist accident reconstructions using video of drive recorder

Objective: Though autonomous emergency braking (AEB) systems for car-to-cyclist collisions have been under development, an estimate of the benefit of AEB systems based on an analysis of accident data is needed for further enhancing their development. Compared to the data available from in-depth accident data files, data provided by drive recorders can be used to reconstruct car-to-cyclist collisions with greater accuracy because the position of cyclists can be observed from the videos. In this study, using data from drive recorders, the performance and limitations of AEB systems were investigated.

Method: Data of drive recorders involving taxi-to-cyclist collisions were collected. Using the images collected from the drive recorders of those taxis, 40 cases of 90° car-to-cyclist intersection collisions were reconstructed using PC-Crash. Then, the collisions were reconstructed again utilizing car models with AEB systems installed while changing the sensor’s field of view (FOV) and the delay time of initiating vehicle deceleration.

Results: The angle of FOV has a significant influence on avoiding car-to-cyclist collisions. Using a 50° FOV with a braking delay time of 0.5?s resulted in avoiding 6 collisions, and using a 90° FOV resulted in avoiding an additional 14 collisions. Even when installing an ideal AEB system providing 360° FOV and no delay time for braking, 8 collisions were not avoided, though the impact velocities were reduced for all of these remaining collisions. These collisions were caused by the cyclists’ sudden appearance in front of cars, and the time-to-collision (TTC) when the cyclists appeared was less than 0.9?s.

Conclusion: The AEB systems were effective for mitigating collisions that occurred due to driver perception delay. Because cyclists have a traveling velocity, a wide-angle FOV is effective for reduction of car-to-cyclist intersection collisions. The reduction of delay time in braking can reduce the number of collisions that are close to the braking performance limit. The collisions that remained even with an ideal AEB system in the PC-Crash simulation indicate that such collisions could still occur for autonomous cars if the traffic environment does not change.     

Prevalence of driver physical factors leading to unintentional lane departure crashes

Objective: Some lane-keeping assist systems in development and production provide autonomous braking and steering to correct unintentional lane drift but otherwise require drivers to fully control their vehicles. The goal of this study was to quantify the proportion of drivers involved in unintentional lane drift crashes who would be unable to regain control of their vehicles to inform the design of such systems.

Methods: The NHTSA's National Motor Vehicle Crash Causation Survey collected in-depth, on-scene data for a nationally representative sample of 5,470 U.S. police-reported passenger vehicle crashes during 2005–2007 that occurred between 6 a.m. and midnight and for which emergency medical services were dispatched. The physical states of drivers involved in the 631 lane drift crashes in the sample, which represented 259,034 crashes nationally, were characterized.

Results: Thirty-four percent of drivers who crashed because they drifted from their lanes were sleeping or otherwise incapacitated. These drivers would be unlikely to regain full control of their vehicles if an active safety system prevented their initial drift. An additional 13% of these drivers had a nonincapacitating medical issue, blood alcohol concentration (BAC) ≥ 0.08%, or other physical factor that may not allow them to regain full vehicle control. When crashes involved serious or fatal injuries, 42% of drivers who drifted were sleeping or otherwise incapacitated, and an additional 14% were impacted by a nonincapacitating medical issue, BAC ≥ 0.08%, or other physical factor.

Conclusions: Designers of active safety systems that provide autonomous lateral control should consider that a substantial proportion of drivers at risk of lane drift crashes are incapacitated. Systems that provide only transient corrective action may not ultimately prevent lane departure crashes for these drivers, and drivers who do avoid lane drift crashes because of these systems may be at high risk of other types of crashes when they attempt to regain control. Active lane-keeping assist systems may need to be combined with in-vehicle driver monitoring to identify incapacitated drivers and safely remove them from the roadway if the systems are to reach their maximum potential benefit.     

Effect of air supply on the performance of an active direct methanol fuel cell (DMFC) fed with neat methanol

Unlike the situation in the direct methanol fuel cell (DMFC) fed with dilute liquid methanol solution, the required water in anode for a DMFC fed with neat methanol is entirely transported from cathode. In this study, the water concentration in anode catalyst layer of such a DMFC operating with fully active mode is theoretically analyzed, followed by the experimental investigations on the effects of air flow rate and operating temperature on cell performance. The results revealed that the air flow rate has a strong impact on cell performance, especially at larger current density. Overmuch air causes rapid decline of cell performance, which results from the dehydration of membrane and lack of water in the anode reaction sites. Raising temperature induces faster reaction kinetics, while undesired stronger water dissipation from the DMFC. In practice, the stable cell resistance can be used as a criterion to help the DMFC to achieve a high and sustainable performance by finely combining the air flow rate and operating temperature.     

土壤中活性铝的流动注射分析

研究了ECR-CTMAB体系测定土壤中活性铝的流动注射分析。结果表明,该方法具有快速、灵敏的特点,进样频率为60个样/时,检出限为0.05μg/ml。用不同提取液提取各地区土壤中活性铝并进行了测定。     

饱和吸氰炭再生方法及其机理的研究

研究了饱和吸氰炭的化学药剂再生与活化方法，确定工作条件，经含Ｈ２Ｏ２，甲醛的０．５ｍｏｌ／ＬＮａＯＨ溶液再生，再用含１０％ＣｕＣｌ２的２ｍｏｌ／ＬＨＣｌ溶液活化后活性炭的性能恢复到原炭的９６％以上，研究表明，经再生与活化后炭样的比表面积所增加，中孔，微孔所占的比例增大，表面含氧基团增多是再生炭获得理想处理效果的主要原因。     

絮凝用聚合物最佳性能的探讨

本文通过对聚合物混凝剂活化的过程进行剖析，提出了水力条件是唯一影响因素，并比较了三类混合器的性能．