On the selection of stimulus for the auditory variant of the detection response task method for driving experiments

Objectives: The detection response task (DRT) is a method for measuring attentional effects of secondary tasks on a driver's cognitive load by measuring response times and hit rates to different types of stimuli as indirect indicators of increased cognitive load. ISO 17488 (International Organization for Standardization 2016) only provides guidelines for the technical implementation and measurement methods for the visual and tactile versions (use of visual and tactile stimuli) of the DRT method. This article presents a study with the goal of finding the most appropriate auditory stimulus for the implementation of an auditory version of the DRT method.

Methods: This article presents the results of an experiment in which responses to 7 different auditory DRT stimuli—varying in frequency—were compared while inducing users' cognitive load with a modified n-back task. The experiment was conducted in a surrogate driving environment and in a within-subject design. Response times, hit rates, and secondary task performances were observed as indicators of increased cognitive load.

Results: Significantly shorter response times were found for the white noise signal compared to single-frequency signals. However, the largest differences in response times, for trials without and with a cognitive task, were found for 4- and 8-kHz single-frequency signals. No significant differences were found for hit rates and secondary task performances between the different stimuli.

Conclusions: Consistent significant differences in response times for all tested stimuli prove that the auditory DRT variant is also sensitive to changes in cognitive load. The mean increase in response times of more than 25% for 4- and 8-kHz signals for trials with a cognitive task compared to trials without one indicates that one of these signals could be used as a potential auditory stimulus for the auditory DRT variant.     

基于二氧化钛纳米管有序阵列的氢气探测

基于气体传感器对H_2的泄漏进行探测监控,可以有效预防和控制H_2火灾爆炸事故的发生。通过阳极氧化法制备了高度有序的二氧化钛(TiO_2)纳米管阵列并制成气体传感器元器件,研究其在空气气氛中对H_2的气敏特性。通过粉末X射线衍射(XRD)、扫描电子显微镜(SEM),透射电子显微镜(TEM)表征手段研究了TiO_2纳米管的相组成和微观结构。TiO_2纳米管具有优异的气敏性能,可在200℃以上对H_2进行有效探测,检测极限达到20ppm。325℃对1 000ppm H_2灵敏度为446,响应时间为2s,对H_2选择性好。     

长江中游荆南三口河系径流演变特征及趋势预测

以荆南三口五站1951~2015年实测径流数据,利用Mark-Kendall趋势突变检验法、累计距平、Morlet复小波等方法分析三口河系径流演变特征;选用ARIMA模型和时间序列模型预测荆南三口河系径流演变趋势。结果表明:(1)荆南三口径流年际变化较大,径流年内分配不均匀,5~10月为丰水期,11月~次年4月为枯水期,呈现出明显季节差异;(2)三口径流总体上呈下降趋势,其中以1959~1980年径流下降趋势最为明显,其趋势幅度p的绝对值达到了698.313,2003~2015年径流下降趋势较为缓慢,无明显趋势,但其p的绝对值仍达到了166.524;(3)运用Mark-Kendall突变检验及累计距平法共同检验,三口径流突变年份为1970年、1985年;(4)1951~2015年间三口径流变化过程主要存在48~58 a、20~28 a、10~18 a 3个尺度的周期变化,以55 a、24 a、14 a为周期中心,其小波方差显示三口径流序列第一、第二、第三主周期分别为55 a、24 a、14 a;(5)三口径流在2016~2030年呈现出先减小后增大的趋势,即2016~2018年为波动增减期,2019~2026年前后为枯水期,2026~2030年为丰水期。     

基于Delaunay三角网和地理加权回归的降水空间异常探测方法研究

针对目前已有的降水资料质量控制方法适应性差,降水数据难以模拟局地降水规律的问题。以湖南省为实验区域,利用1985~2014年夏季降水观测数据,定义局部地理空间内降水量发生显著偏离的气象站点为异常,发展了一种结合Delaunay三角网和地理加权回归的降水空间异常探测方法。该方法通过构建不规则三角网来获取各个区域之间稳定合理的地理邻近关系,根据空间邻近关系获取自适应回归带宽,并纳入地理加权回归模型进行计算,最后根据回归残差项的统计分布性质开展空间异常度量与分析。实验表明该方法能有效检测出降水空间异常,可应用于降水数据二次处理时的质量控制阶段,有助于进一步探索局部地理空间内的降水规律。     

Colorado River Floods, Droughts, and Shrimp Fishing in the Upper Gulf of California, Mexico

Accurate procedures that measure hydrologic variability would have great value for evaluating ecosystem impacts of upstream water use in the Colorado River Basin. Many local extractive income-based stakeholders rely directly or indirectly on ecosystem health and are adversely affected when the river does not flow. This study focuses on the impact of little or no Colorado River flow on the Mexican shrimp industry. Although there have been complaints that U.S. diversions of Colorado River flow have greatly impaired the shrimp fishery, this research demonstrates that freshwater rarely reaches the Gulf even during times of flooding, and that other factors such as overfishing may influence the instability of shrimp populations. Advanced very-high-resolution radiometer (AVHRR) satellite imagery was used to assess water volumes diverted away from the channel of the Colorado River and ultimately the Gulf of California during flooding periods. Analysis of data demonstrated that little freshwater actually reaches the Gulf even during floods because of its diversion into a large dry lake bed basin known as Laguna Salada. Fuller use of the Colorado River throughout its entire course to the sea is possible and could benefit a large cohort of users without catastrophic habitat destruction in delta ecosystems. Reconstruction of a natural earthen berm, as proposed by Ducks Unlimited, would maximize the use of floodwaters for ecosystem benefits. These findings have profound implications for local economic activities dependent on hydrologic resources in the Colorado River Delta and Upper Gulf.     

环境决策支持系统的设计技术及发展趋势

简要论述了环境决策支持系统(EDSS)的发展历程,提出了EDSS开发技术的六大构成部分:应用平台的选择;系统的开发方式的选择;系统的开发工具的选择;系统的组成结构的建立;系统的基本功能的设计;系统的开放接口的设计。对系统设计的关键技术进行了分析,依据EDSS的应用现状,指出EDSS的发展趋势,对实际应用具有一定的指导意义和实用价值。     

水中六价铬光纤传感检测方法的研究

探讨光纤传感检测探头的原理,建立适应现场检测水中六价铬的方法。水中Cr6+与二苯基碳酰二肼反应生成紫红色产物,光纤探头插入水样中进行测定。其检测浓度范围为0.04～1.0mg/L,最低检出限为0.04mg/L。采用光纤传感测定水中六价铬,为野外和在线检测提供一种新方法。     

总汞环境样品的前处理技术及分析方法研究进展

对2005—2012年间的环境样品中总汞检测的前处理技术及分析方法文献进行了综述。总结了水体、土壤及废气中总汞样品前处理采用的主要方法及存在的问题,并且对环境样品总汞的现行国标分析方法及新方法(光度法、冷原子吸收法、原子荧光法、电感耦合等离子体-质谱法及生化检测等)的原理和应用进行了归纳。展望了环境样品中总汞检测的发展趋势,为研究者进行总汞新分析方法的开发和标准化提供了借鉴。     

新形势下地市级环境监测站转型发展初探

以南京市环境监测中心站的实践为例,初步探讨了地市级环境监测站转型发展的优势和困难、总体思路和分步措施。针对转型中存在的人力不足、人才培养滞后、制度和机制与发展需求不匹配等问题,引入社会检测力量,释放人力,促进人员初步转型,并建立组织管理体系、资金管理体系和质控管理体系,试行人员持证上岗制,为顺利转型提供保障。提出强化人才转型、对外的质控与监管、对内的精细化管理、监测成果的挖掘分析,以及对区县站的扶持,进一步深化转型发展。     

低浓度SO2和NOx 自动监测系统性能评价方法

通过对7种废气自动监测系统的比较研究和现场测试,提出了非分散红外法、紫外差分法、紫外荧光法、化学发光法等多种 SO2和 NO x 自动监测技术在低浓度范围实现准确定量监测的性能评价方法,定义了 CEMS 的系统检出限及其主要影响因素。建议采用系统检出限、线性误差等关键参数作为低浓度 CEMS 的性能评价方法,提出将全系统多点标准气体校准或加标回收率作为验收和质控监督的基本方法。