TRANSPORT OF ROAD-SURFACE SEDIMENT THROUGH EPHEMERAL STREAM CHANNELS1

ABSTRACT: Since the majority of road drainage points in western Washington and Oregon enter small, often ephemeral streams rather than large, fish-bearing waters, impact of road-surface sediment on biota in permanent streams depends, to a large extent, on transport through these small watercourses. A series of experimental additions of road-surface sediment was made to two ephemeral streams to examine the downstream transport of this material as a function of discharge and channel characteristics. These small streams were found to store large amounts of sediment washed from road surface. In no instance did either stream transport more than 45 percent of the added material to their mouths, distances of 95 and 125 m. Larger-sized sediment particles were delivered at a lower rate than finer material. Added sediment <0.063 mm in size was transported efficiently through the systems at all but the lowest flows tested. Material between 0.5 and 0.063 mm and from 2.0 to 0.5 mm in size were retained at progressively higher rates, with sediment in the coarser size category never exceeding a delivery of 10 percent of the added material. There were significant differences in the transport of sediment in the two larger size categories between the two streams. These differences were due to a much greater amount of woody debris in the stream with the lower delivery rates, which acted to trap and hold sediment, as well as a slightly longer and less steep channel.     

灾区医疗队生存和救治中的问题及对策

针对灾区医疗队生存和救治工作中存在的问题，提出了解决办法，包括吃、住、行及救治等方面。     

矿井岩爆及其失稳理论

对若干岩爆发生实例进行了分析；回顾了历史上相继提出的几种主要的岩爆发生理论，对各种理论提出的岩爆发生的判别准则进行了讨论； 对近几年发展起来的关于岩爆的失稳理论进行了深入的阐述，指出失稳理论包含了其他各种岩爆发生理论的合理部分，因而更符合岩爆发生的实际；介绍了失稳理论在若干典型岩爆问题中的应用     

特厚煤层巷道冲击特征及冲击危险性评价方法研究

通过研究特厚煤层巷道能量储存、应力分布及围岩强度特征,揭示了特厚煤层巷道与薄及中厚煤层相比具有储存能量多、应力影响范围广及围岩强度低的主要冲击特征。基于特厚煤层巷道冲击特征和冲击地压启动理论,提出了综合弹性能指数、应力比指数和冲击能量速度指数的冲击危险性评价多元指数法,建立了特厚煤层巷道冲击危险性的综合评价指标体系。将该评价指标体系应用于陕西某矿特厚煤层掘进期间巷道冲击危险性评价,根据评价结果对冲击地压危险区域采取了合理的卸压措施,保证了工作面的安全开采。     

基于机器学习的侵财类案件危害程度分析

为了进一步分析侵财类案件的危害程度,以抢劫、抢夺和盗窃3种典型侵财类案件为例,利用ZS市2008—2014年的犯罪数据与统计年鉴数据,提取“发案时间”“发案地域”“选择时机”“选择处所”“选择对象”“人均地区生产总值”“职工月平均工资”7个特征,建立基于多种机器学习分类算法的侵财类案件危害程度预测模型,并进一步开展预测结果的分析研究。研究结果表明:梯度提升决策树（GBDT）算法性能最优,危害程度预测准确率达到了0.88;在抢劫案和抢夺案中,一般和重大的案件容易发生在繁华地带,特大案件容易发生在其他处所;侵财类案件倾向于在工作日的城区中发生,发生的危害程度大多为一般;提出的侵财类案件危害程度预测模型可为侵财类案件的风险评估及警务资源优化配置工作提供方法支持。     

水资源开发与利用科研工作的现实制约与对策建议

中国人均水资源量少、水资源时空分布不均,近年来经济社会对水资源需求日益增大。在相关领域科技成果的大力支撑下,中国走出了一条有效的水资源管理之路,实现了水资源的高效利用和有效保护。但目前在水资源开发利用的科技活动中仍存在一定的现实制约,本文进行了一定分析,并提出了对策建议。     

事故调查报告中事故原因分析的改进*——基于企业事故案例学习视角

为进一步提高我国事故调查报告的质量,更好地满足企业对事故案例学习的需要,通过案例分析事故调查报告中事故原因部分存在的问题及其原因,并在此基础上提出采用事故致因理论来改进事故调查报告的思路;应用24Model改进天嘉宜化工有限公司“3·21”特别重大爆炸事故的事故原因分析,以此来验证本文思路的可行性和有效性。研究结果表明,使用事故致因理论能够更加科学地归纳事故原因,增强措施的针对性和可操作性,可有效改善事故调查报告的质量。     

Risky scenario identification in a risk perception scale for construction workers in Thailand

Introduction: Construction sites exhibit unique hazardous characteristics. Hence, investigating the causes of fatal and nonfatal accidents is extremely important to promote safety on construction sites. Literature shows a risk perception (RP) scale for construction workers; to expand the existing research, this study aims to identify risky scenarios for assessing the RP of Thai construction workers, with the goal of reducing workplace incidents. Method: The scale development process consists of four phases. Item development was also performed, followed by factor analysis. Reliability and validity assessments were finalized in the process. A survey of 500 construction workers in Thailand was conducted to investigate risky scenarios. Through the process, a total of 17 items remained in the final RP scale, and the reliability and validity of these items were confirmed. Results: The RP scale was affirmed to have four dimensions (probability, severity, worry, and unsafe). These dimensions of workers’ RP were negatively correlated with the workers’ risk-taking behaviors. This study further showed that participants with a high level of affective RP were more likely to have a high level of cognitive RP. Hence, those with a high level of RP tended to be involved in fewer risk-taking behaviors. Practical Applications: The final version of the scale was reliable and valid in determining the RP and risk-taking behaviors of construction workers in Thailand.     

基于多故障冲击模型和故障树的PFDavg计算方法研究*

为提高安全仪表功能（SIF）要求时危险失效平均概率（PFDavg）计算结果的精确度,提出1种能准确计算SIF在多重共因失效影响下的PFDavg的数学模型。建立包含多重共因失效的系统失效故障树,然后利用多故障冲击模型区分普通失效率和多重共因失效率,根据瞬时不可用率的定义和故障树的逻辑关系计算出SIF的瞬时不可用率;基于PFDavg的定义,计算出SIF的PFDavg,以某化工企业SIF为例进行验证。结果表明:方法有效考虑了多重共因失效对SIF的影响,通过模型计算出SIF的PFDavg大于基于马尔可夫（Markov）方法的软件计算结果,但二者处于相同的数量级。模型在评估SIF的PFDavg时比传统方法偏保守,能提高安全仪表功能的安全性。     

克百威农药对我国湿地鸟类的威胁及其对策

介绍了我国湿地鸟类就地保护现状以及克百威农药在我国的使用,对鸟类的毒性、毒害途径和主要影响区域.针对当前我国克百威农药使用量大,对湿地鸟类构成严重威胁的实际情况,提出了具体的保护对策,包括:筛选一批重要湿地自然保护区进行严格管护;筛选出我国首批禁用克百威农药的市、县;完善湿地鸟类保护与自然保护区法律法规建设;调整农药产品结构,示范推广高效低毒的新农药品种;提高自然保护区管理水平,对毒害鸟类案件严格执法;加强对农药销售和使用的管理.