Safety-related conclusions for the application of ultrasound in explosive atmospheres

International safety regulations such as EN 1127-1 consider ultrasound to be an ignition source. Currently, applications of ultrasound in explosive atmospheres have to comply with a threshold value of 1 mW/mm². However, it is unclear as to how this intensity has to be measured and, therefore, this threshold value is poorly defined. Moreover, it is based on theoretical estimations in analogy to other ignition sources and there are no publications or significant records on these estimations. Within a research project at PTB, it has now been investigated experimentally in relation to worst-case considerations including airborne ultrasound, focused MHz ultrasound in liquids and acoustic cavitation. On the basis of the results of the research it is now possible to revise the current regulations and to specify measures for safe operation of ultrasonic applications in explosive atmospheres. In this context, for ultrasound coupled directly to gaseous atmospheres a new threshold value of 170 dB (re. 20 μPa) can be suggested, and for ultrasonic applications in liquids, an augmentation can be made to the threshold to 400 mW/mm².     

广州轨道交通三号线高速行驶条件下对安全限界的影响研究

给出了轨道交通车辆横向偏移量的计算方法 ,并应用列车 -线路动力耦合模型 ,分析了广州地铁三号线的安全限界变化问题。确定了当前按 80km/h行车速度设计的建筑限界能满足 13 0km/h行车速度的要求 ,限界尺寸不需改动可保证列车运行安全平稳     

有意违章行为动因分析与控制对策探讨

对有意违章行为的含义进行了界定 ,并对有意违章行为产生的动因进行了详细分析 ,提出了有意违章行为的动因主要包含违章行为与遵章行为满足生理心理需要作用的差值ΔXW、违章行为会受到法规惩处的作用FW、违章行为可导致人身伤害的主观感觉的作用RW3个方面。同时对 3个方面的动因按弗鲁姆的激励理论进行了转化 ,给出了各自的含义说明。笔者按动因分析的结果 ,给出了控制有意违章行为的步骤和措施     

Bioassay: A useful tool for evaluating reclaimed water safety

Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis. However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conventional water quality standards have difficulty guaranteeing the safety of reclaimed water. Bioassays can vividly reflect the integrated biological effects of multiple toxic substances in water as a whole, and could be a powerful tool for evaluating the safety of reclaimed water. Therefore, in this study, the advantages and disadvantages of using bioassays for evaluating the safety of reclaimed water were compared with those of conventional water quality standards. Although bioassays have been widely used to describe the toxic effects of reclaimed water and treatment efficiency of reclamation techniques, a single bioassay cannot reflect the complex toxicity of reclaimed water, and a battery of bioassays involving multiple biological effects or in vitro tests with specific toxicity mechanisms would be recommended. Furthermore, in order to evaluate the safety of reclaimed water based on bioassay results, various methods including potential toxicology, the toxicity unit classification system, and a potential eco-toxic effects probe are summarized as well. Especially, some integrated ranking methods based on a bioassay battery involving multiple toxicity effects are recommended as useful tools for evaluating the safety of reclaimed water, which will benefit the promotion and guarantee the rapid development of the reclamation and reuse of wastewater.     

Identification of potential electrotrophic microbial community in paddy soils by enrichment of microbial electrolysis cell biocathodes

Electrotrophs are microbes that can receive electrons directly from cathode in a microbial electrolysis cell (MEC). They not only participate in organic biosynthesis, but also be crucial in cathode-based bioremediation. However, little is known about the electrotrophic community in paddy soils. Here, the putative electrotrophs were enriched by cathodes of MECs constructed from five paddy soils with various properties using bicarbonate as an electron acceptor, and identified by 16S rRNA-gene based Illumina sequencing. The electrons were gradually consumed on the cathodes, and 25%–45% of which were recovered to reduce bicarbonate to acetic acid during MEC operation. Firmicutes was the dominant bacterial phylum on the cathodes, and Bacillus genus within this phylum was greatly enriched and was the most abundant population among the detected putative electrotrophs for almost all soils. Furthermore, several other members of Firmicutes and Proteobacteria may also participate in electrotrophic process in different soils. Soil pH, amorphous iron and electrical conductivity significantly influenced the putative electrotrophic bacterial community, which explained about 33.5% of the community structural variation. This study provides a basis for understanding the microbial diversity of putative electrotrophs in paddy soils, and highlights the importance of soil properties in shaping the community of putative electrotrophs.     

爆炸螺栓分离对热防护系统冲击响应分析

目的考察在爆炸螺栓分离过程中,作用在TPS(热防护系统)上的冲击响应是否会导致其破坏,从而影响航天器飞行安全,对过程进行数值仿真分析。方法提出四阶段仿真方案,基于MSC.Dytran软件,采用流固耦合方法对爆炸螺栓分离过程进行动力学仿真;根据单个爆炸螺栓地面分离试验的结构进行建模和分析,获取结构响应曲线;再根据实测的冲击响应数据,对爆炸过程中炸药及JWL方程的参数等设置进行调整,获取准确爆炸螺栓的分析模型;最后应用于对真实结构中TPS(热防护系统)在分离过程里受爆炸螺栓冲击响应的动力学分析与评估。结果通过参数调整,获得的仿真模型与爆炸螺栓地面分离试验实测结果一致,证明了仿真模型的有效性和四阶段仿真方案的可行性。结论提取的真实结构爆炸螺栓分离过程中作用在TPS(热防护结构)上的最大加速度响应曲线,可用于指导TPS(热防护系统)的设计。     

爆炸法处理废旧轮胎制造橡胶粉末技术及关键机理研究

主要介绍了利用爆炸法处理废旧轮胎制造橡胶粉末的技术 ;探讨了橡胶在爆炸作用下破坏的机理 ,爆炸法中橡胶变形速率与它的剪切模量和断裂韧性的关系 ;分析了利用直接爆炸法处理废旧轮胎的 3种实验结果 ,验证了对轮胎进行预处理的必要性 ,探讨了炸药用量的选择原则     

论我国自然资源产权制度的改革

我国自然资源产权制度长期以来界定不清晰和不合理，造成自然资源配置的效率损失很大，本文根据许多实例和交易成本理论来说明５０年代中期以来我国自然资源的一些主要产权制度的利弊，并提出未来改革的一些设想。     

铁路运输安全事故灰色预测方法研究

近年来 ,我国铁路运输发展迅猛 ,尤其是列车运行多次提速 ,列车运行密度加大 ,对铁路运输安全管理不断提出了新的要求。依靠科技进步 ,尽量防止或减少安全事故的发生 ,要应用安全信息技术 ,使安全管理人员对铁路运输安全现状及未来事故发展趋势有所了解 ,提高安全防范意识及事故处理能力 ,同时还要不断提高员工的安全意识和安全文化素质 ,这些方法对于提高安全管理水平 ,降低事故的发生 ,保护人民的生命安全与健康具有重要意义。铁路运输安全事故预测技术就可很好解决上述问题。笔者应用灰色预测理论 ,建立了铁路运输安全事故预测模型 ,开发了安全事故预测软件系统 ,并以某铁路运输企业为例 ,介绍了研制的灰色预测系统软件的应用效果     

在实践中不断提高安全预评价的质量

笔者结合建设项目劳动安全预评价的工作实践 ,分析了安全预评价中存在的主要问题 ,介绍了首都经贸大学劳动安全卫生评价中心在安全预评价工作中的有益探索和成功经验 ,提出了进一步提高安全预评价质量的建议 ,努力寻求一条使安全预评价质量持续改进、不断提高的有效途径。