成渝高速铁路地面三向振动总值特性分析

为研究高速铁路地面三向振动总值特性,选择成渝高速铁路某路堤段和桥梁段进行了现场地面三向振动测试,分析了振动总值随距离的变化特性。结果表明,路堤段和高架桥段计权和未计权振动总值均随距离增加而近似呈负指数衰减,近场衰减快,远场衰减缓慢;路堤段和高架桥段计权振动总值与Z振级随距离的变化规律类似,且近场两者之间的差值较小,当评价高速铁路运营振动的环境影响时,近场可用Z振级近似代替计权振动总值。     

可靠性分配理论在系统安全目标实现中的应用

在系统安全理论中,确定各基本事件的可靠度以实现所给定的系统安全目标值问题一直没有得到很好解决。笔者将可靠性分配理论与故障树分析方法相结合,提出了2个层次可靠度分配法:最小割集之间采取可靠度再分配法,对构成最小割集的各个基本事件之间采取等分配法。从而建立系统中各单元可靠度再分配量化模型。为便于应用,通过实例,详述系统各单元可靠性分配的计算过程。研究表明,运用该模型可准确、简便地计算出各单元的可靠度,使系统在给定的目标值条件下达到系统的安全性优化。     

Time allocation between work and recreation and the associated injury risks among young people

PROBLEM: The purpose of this study was to examine the relationship between overall risk of injury and time use patterns between work and active recreation among adolescents and young adults. METHODS: Using a representative sample of 9,795 Canadians aged 15-24 years, a multivariate logistic regression on the likelihood of any medically attended injury was conducted, including sociodemographic, individual, and time factors. RESULTS: Young people who engaged in a combination of high work and high activity hours were twice as likely to sustain a medically attended injury compared to those who worked low hours, but did not participate in any recreational activity. Those respondents who were not in school had a 43% increase in injury risk compared to full-time students. SUMMARY: Our findings suggest that injury risk was not a simple function of fatigue and cumulative exposure time. Our findings suggest the importance of considering time use and the associated injury risk tradeoffs. IMPACT ON INDUSTRY: Relevant to state and federal work safety policy makers, our findings suggest the importance of understanding where youth might otherwise spend their time if constraint were placed on their employment opportunities, and the associated injury risk tradeoffs must be taken into consideration.     

沙柳活性炭纤维的制备与表征

以（NH4）2HPO4活化沙柳纤维制备活性炭纤维,L16（45）正交实验优化制备工艺条件,重点研究了活化温度对活性炭纤维结构的影响。同时应用扫描电镜（SEM）对其表面形貌进行表征,通过N2吸附-脱附测定其孔结构。结果表明,随着活化温度的升高,活性炭得率逐渐减小,碘吸附值先增大后减小,在浸渍比2.5：1、预氧化温度200℃、预氧化时间90 min、活化温度为800℃、活化时间60 min的条件下,可以制备出比表面积为1 304 m2·g-1、总孔容为1.004 cm3·g-1、得率为31.6%、碘吸附值为1 321 mg·g-1的纤维状活性炭。     

总氮测定中的注意事项

碱性过硫酸钾消解紫外分光光度法测定总氮中，对空白值偏高的影响因素进行了实验和分析，提出了几点建议及改进措施。     

Detection of organic pollutants in sandy soils via TDR and eigendecomposition

In this study, organic pollutants in sandy soils are detected using a time domain relectrometry (TDR) probe system and eigendecomposition technique. As a demonstration, four types of organic fluids (motor oil, diesel oil, methanol and ethanol) were examined. Samples were prepared with different combinations of deionized water and organic fluid contents. For each experiment, reflected signals were captured by an oscilloscope, and their characteristics were identified using eigendecomposition technique. Autoregressive modeling and singular value decomposition methods were utilized for calculating the eigenvalues. The most significant eigenvalues were then identified based on their relative magnitude. Experimental results indicated that the presented system is sensitive to both water and pore fluid organic contents. For saturated conditions, signature curves were determined for identification of organic and/or water contents in soil pore fluids.     

让实验室测试值更贴近真实世界防护值——护听器的声衰减值评价方法讨论

本文介绍了护听器声衰减值的评价方法,对比了我国、ISO、欧洲EN、美国ANSI和澳大利亚新西兰AS/NZS标准中关于护听器声衰减值评价方法的差异。着重讨论在测试过程中,使用不同的受试者和护听器佩戴方式得出的检测数据与真实世界防护值的一致性情况。研究表明,使用"受试者自行佩戴"的方式测得的数据能更好地反映护听器在真实世界的防护性能。     

打造零事故的建筑安全文化

在研讨安全文化和建筑安全文化内涵,分析国内外建筑安全文化研究与国内实施现状的基础上,研究了5家国际建筑企业的安全创新活动,包括:企业背景、方案、实施过程等。结合利害关系者原理、风险管理和安全知识管理,笔者提出:要实现安全行为,应注重塑造员工的安全信念、态度和承诺;应有高层管理人员强有力的支持,将整个建筑业供应链的利害关系者都纳入到安全管理中,风险管理和安全知识管理的运用可促进零事故安全文化的形成。同时提出构建在我国实现零事故的建筑安全文化的流程,即承认-启动-执行-监督-更新的步骤,给出了一种提高员工安全知识、坚定员工安全信念、塑造员工安全态度、形成安全行为并最终打造健全安全文化的整体策略。     

恶臭物质的嗅觉阈值与致臭机理研究概况与展望

嗅阈值是表征气味物质特性的重要指标,对认识异味污染的形成机理、恶臭评估及污染控制有重要意义.围绕嗅阈值的测定方法、嗅阈值与分子结构的关系及复合臭气评估模型,论述国内外相关研究的概况,在指出现有研究不足的同时,提出有待解决的关键问题及重点研究内容.     

煤矿水害风险量化评价方法

为提高煤矿防治水管理水平,预防和消除矿井水害,在层次分析法的基础上建立中性值作为参照对象对矿井水害风险进行实时评判的方法。根据《煤矿防治水细则》建立以矿井水文地质类型、矿井涌水量标准分数、突水预兆、采掘面位置、探水结果为准则层的层次结构模型,并对各评价指标赋权。依据制定的水害风险评价指标的评分细则和监测监控数据并结合其权重得到水害评价总得分。通过总得分与中性参照分数比较得出预测结果:水害评价总得分大于中性参照分数,证明水害的威胁小,分数越高越安全;反之则水害的威胁较大,分数越低越危险,这时需要加强防治水的力度,令评价分数管控大于中性参照分数。这种方法依赖于井下监测监控数据进行量化评价,能实时、客观、全面且准确地反映煤矿水害的风险情况。