我国精密可控震源主动探测研究进展

精密可控震源对地发射扫频信号,通过高精度的观测系统获得记录资料,采用专门的数据处理方法来提取信号,获得地下介质的信息。介绍现有的一些数据处理方法,比如匹配滤波、反褶积、Wigner-Hough变换和时变滤波等,可以实现可控震源信号提取。并总结这些方法的优缺点。通过多次野外科学实验发现,精密可控震源技术是一种探测地下介质结构及变化的有效途径。针对精密可控震源探测的影响因素,还需要开展深入研究,以便于改善其探测距离和分辨能力。     

新旧桥梁承载能力评定对比研究

基于36座新建桥梁及26座既有旧桥静、动载试验,将其在荷载作用下挠度、应变及振动频率的现场实际值与有限元计算理论值进行对比分析,获取了新旧桥梁的挠度、应变及频率的检验系数,并在此基础上获取了新旧桥梁的承载能力对比情况。结果表明,既有旧桥承载能力下降明显。这将为类似桥梁检测及承载能力评估提供参考。     

Drowsy drivers: The effect of light and circadian rhythm on crash occurrence

Drowsiness has been recognized as a pervasive problem for drivers, with effects comparable to alcohol. Alcohol, however, has a clear legal limit for impairment; there are no comparable criteria to suggest sleepiness. Drowsiness has been associated with light and circadian rhythm. To investigate the joint effects of these factors on crash occurrence, along with other factors, single vehicle crashes reported in Ontario (1999–2004) were analyzed. Crashes occurring at four times of day, when light varies and circadian rhythm is low (2–5 a.m. and 2–4 p.m.) and with similar light conditions and higher circadian rhythm (9–11 p.m. and 10 a.m.–12 noon). Logistic regression was used to see how light and other factors are associated with single vehicle crashes occurring at times of low circadian rhythm, when drowsiness is more likely.Initial results indicated many circumstances associated with occurrence at these times: the age and sex of the driver and reported driver condition as well as weather. There is, however, an interaction between light and presumed alertness. In separate analyses for daytime and night time crashes most variables were significant for nighttime crashes but not for daytime events. The effects of alcohol and youth remained. A lack of light may exacerbate the effects of other factors at times of low alertness; this should be further investigated in controlled environments such as sleep laboratories and/or driving simulators.     

Influence of visual clutter on the effect of navigated safety inspection: a case study on elevator installation

Introduction. Navigated safety inspection based on task-specific checklists can increase the hazard detection rate, theoretically with interference from scene complexity. Visual clutter, a proxy of scene complexity, can theoretically impair visual search performance, but its impact on the effect of safety inspection performance remains to be explored for the optimization of navigated inspection. This research aims to explore whether the relationship between working memory and hazard detection rate is moderated by visual clutter. Methods. Based on a perceptive model of hazard detection, we: (a) developed a mathematical influence model for construction hazard detection; (b) designed an experiment to observe the performance of hazard detection rate with adjusted working memory under different levels of visual clutter, while using an eye-tracking device to observe participants’ visual search processes; (c) utilized logistic regression to analyze the developed model under various visual clutter. Conclusion. The effect of a strengthened working memory on the detection rate through increased search efficiency is more apparent in high visual clutter. This study confirms the role of visual clutter in construction-navigated inspections, thus serving as a foundation for the optimization of inspection planning.     

Risk assessment of offshore crude oil pipeline failure

Failure of Leak Detection System (LDS) to detect pipeline leakages or ruptures may result in drastic consequences that could lead to excessive financial losses. To minimize the occurrence of such failure, the functionality of the LDS and the integrity of the pipeline should be assessed on a priority basis. This paper presents an integrated risk-based assessment scheme to predict the failure and the failure consequences of offshore crude oil pipelines. To estimate risk, two important quantities have to be determined, the joint probability of failure of the pipeline and its LDS and the consequences of failure. Consequences incorporate the financial losses associated with environmental damage, oil spill cleanup and lost production. The assessment provides an estimate of the risk in monetary value and determines whether the estimated risk exceeds a predefined target risk. Moreover, the critical year for the asset can be determined. In essence, the outcome of the assessment facilitates an informed decision-making about the future of the asset.     

循环冷却水水垢中锌含量测定优化实验研究

对工业循环冷却水水垢中锌含量的测定方法进行了系统优化,主要考察了样品酸度、缓冲溶液添加量、试剂时效性、样品中铁离子量、掩蔽剂量和滴定剂浓度对锌含量检测效果的影响。结果表明:样品酸度控制在pH=4.9~5.1范围内,乙酸-乙酸钠缓冲溶液添加量为30 m L时,锌含量检出值最大,指示剂灵敏度最佳;试剂乙酸-乙酸钠在20 d内使用、二甲酚橙指示剂即配即用对滴定终点的判断效果较好;锌含量测定前应先检测样品中铁离子含量,若铁离子≥40%则应先沉淀过滤后方可进行测定;锌含量检出值随掩蔽剂添加量呈先升后降的趋势,并在3.2 g时滴定效果最佳;滴定剂浓度为0.010 mol/L时锌含量检出值最高;优化实验测定结果接近真实值,方法准确可靠。     

固相萃取-原子荧光光谱法测定土壤中的砷

采用硝酸-氢氟酸-盐酸体系微波消解土壤并结合On-Guard ⅡH柱去除消解液中重金属,原子荧光光谱法测定土壤中的砷。本方法前处理操作过程简单、省时、省力、酸用量少,砷的加标回收率为94.4％～105.6％,能够满足环境监测分析的要求。     

Vigilance monitoring for operator safety: A simulation study on highway driving

INTRODUCTION: Alertness of individuals operating vehicles, aircrafts, and machinery is a pre-requisite for safety of the individual and for avoiding economic losses. In this paper, we present a new technique for determining the alertness level of the operator and elaborate the methodology for the specific case of highway driving METHOD: Our hypothesis is that the time derivative of force exerted by the driver at the vehicle-human interfaces can be used to construct a signature of individual driving styles and to discern different levels of alertness RESULTS: In this study, we present experimental results corroborating this hypothesis and introduce a parameter, 'spikiness index,' for the time series data of the force derivative to quantify driver alertness IMPACT ON INDUSTRY: The low cost, ruggedness, and low-volume data processing requirements of the proposed technique give it a competitive edge over existing predominantly image processing based vigilance monitoring systems.     

环境中大肠杆菌快速生物检测技术研究进展

大肠杆菌作为水质卫生学指标,在环境水质监测中起着非常重要的指示作用.近年来为了克服大肠杆菌常规监测方法的不足,基于现代生物技术原理展开的环境中大肠杆菌的快速检测技术是国内外的研究热点.本文对环境介质大肠杆菌的分子生物学监测方法、免疫学检测方法等的原理及其在环境领域中的应用进行了综述和分析,并在此基础上对大肠杆菌的仪器化发展进行了展望.指出以现代生物技术为核心的并结合现代仪器技术的大肠杆菌快速检测技术将具有良好的应用前景,大肠杆菌的快速检测技术应向操作简单、快速、高灵敏度以及低成本方向发展.     

在用机动车尾气排放检测简易瞬态工况法监管策略

针对简易瞬态工况法机动车尾气排放检测过程中层出不穷的违规检测现象,为对其检测过程实施有效监管,通过分析简易瞬态工况法的检测原理,筛选出可用于监管的车辆基准质量、(CO+CO2)浓度、O2浓度、实时检测尾气流量4个参数,分析其用于监管的原理和理由,并通过五气分析仪漏气实验和实测尾气流量异常案例验证其监管可行性,以期为监管...