Effect of heat transfer through the release pipe on simulations of cryogenic hydrogen jet fires and hazard distances

Jet flames originated by cryo-compressed ignited hydrogen releases can cause life-threatening conditions in their surroundings. Validated models are needed to accurately predict thermal hazards from a jet fire. Numerical simulations of cryogenic hydrogen flow in the release pipe are performed to assess the effect of heat transfer through the pipe walls on jet parameters. Notional nozzle exit diameter is calculated based on the simulated real nozzle parameters and used in CFD simulations as a boundary condition to model jet fires. The CFD model was previously validated against experiments with vertical cryogenic hydrogen jet fires with release pressures up to 0.5 MPa (abs), release diameter 1.25 mm and temperatures as low as 50 K. This study validates the CFD model in a wider domain of experimental release conditions - horizontal cryogenic jets at exhaust pipe temperature 80 K, pressure up to 2 MPa ab and release diameters up to 4 mm. Simulation results are compared against such experimentally measured parameters as hydrogen mass flow rate, flame length and radiative heat flux at different locations from the jet fire. The CFD model reproduces experiments with reasonable for engineering applications accuracy. Jet fire hazard distances established using three different criteria - temperature, thermal radiation and thermal dose - are compared and discussed based on CFD simulation results.     

Can child-pedestrians’ hazard perception skills be enhanced?

ObjectiveTraffic collisions yield a substantial rate of morbidity and injury among child-pedestrians. We explored the formation of an innovative hazard perception training intervention – Child-pedestrians Anticipate and Act Hazard Perception Training (CA²HPT). Training was based upon enhancing participants’ ability to anticipate potential hazards by exposing them to an array of traffic scenes viewed from different angles.MethodTwenty-four 7–9-year-olds have participated. Trainees underwent a 40-min intervention of observing typical residential traffic scenarios in a simulated dome projection environment while engaging in a hazard detection task. Trainees were encouraged to note differences between the scenarios presented to them from separate angles (a pedestrian's point-of-view and a higher perspective angle). Next, trainees and control group members were required to perform crossing decision tasks.ResultsTrainees were found to be more aware of potential hazards related to restricted field of view relative to control.ConclusionsChild pedestrians are responsive to training and actively detecting materialized hazards may enrich child-pedestrians’ ability to cross roads.     

爆破工程安全评价初探

开展爆破工程安全评价可有效地减少各种危险和有害因素 ,减少爆破事故的发生 ,大型或特殊爆破工程均应进行安全评价。本文提出了对爆破工程开展安全评价的设想 ,并对爆破工程安全评价的内容和方法进行了探讨。文中指出 :根据爆破工程的特点 ,可采用事故树分析和预先危险性分析等方法进行爆破工程的安全评价     

灾害荷载下混凝土框架可靠性分析

本文研究了在灾害荷载作用下 ,构件发生剪切破坏的钢筋混凝土框架结构可靠度计算 ,并通过一算例 ,说明在灾害荷载作用下进行混凝土框架结构可靠度分析时考虑剪切破坏的必要性     

Large-scale radon hazard evaluation in the Oslofjord region of Norway utilizing indoor radon concentrations, airborne gamma ray spectrometry and geological mapping

We test whether airborne gamma ray spectrometer measurements can be used to estimate levels of radon hazard in the Oslofjord region of Norway. We compile 43,000 line kilometres of gamma ray spectrometer data from 8 airborne surveys covering 10,000 km² and compare them with 6326 indoor radon measurements. We find a clear spatial correlation between areas with elevated concentrations of uranium daughters in the near surface of the ground and regions with high incidence of elevated radon concentrations in dwellings. This correlation permits cautious use of the airborne data in radon hazard evaluation where direct measurements of indoor radon concentrations are few or absent. In radon hazard evaluation there is a natural synergy between the mapping of radon in indoor air, bedrock and drift geology mapping and airborne gamma ray surveying. We produce radon hazard forecast maps for the Oslofjord region based on a spatial union of hazard indicators from all four of these data sources. Indication of elevated radon hazard in any one of the data sets leads to the classification of a region as having an elevated radon hazard potential. This approach is inclusive in nature and we find that the majority of actual radon hazards lie in the assumed elevated risk regions.     

Designing for construction workers’ occupational health and safety: a case study of socio-material complexity

Drawing upon an empirical analysis of the design and construction of a food processing facility, a theoretical understanding of the impact of design decision-making on the occupational health and safety (OHS) of construction workers is developed. It is argued that current policy and legislative approaches to Construction Hazard Prevention through Design (CHPtD) are inherently limited because they do not adequately reflect the socio-material complexity of decision-making in construction design. Specifically, the simplistic attribution of responsibility to a single socio-technical actor, ‘the designer’, does not reflect the multiple and disparate influences that impact upon OHS outcomes. Nor do existing CHPtD policy frameworks, management processes and tools recognize the manner in which the interactions and associations between relevant project stakeholders and various non-human artefacts shape (and are also influenced by) the evolution of design decisions. Drawing on actor-network theory (ANT) and using embedded units within a case study approach, the interactions between human actors and non-human artefacts are explored in relation to the design of four components of the food processing facility. The way in which design decisions unfolded and shaped OHS experiences during the construction stage of the project is revealed. The research highlights limitations inherent in current approaches to the management of CHPtD and the need to develop a more robust theoretically based approach to integrating OHS considerations into construction design practice.     

城市空间快速增长的区域生态风险防御——国际经验检讨与规划调控初探

我国城市空间快速增长引发了日益加剧的区域生态风险,对实现可持续城市化构成严峻挑战。尽管从城市自身尺度的环境影响控制迈向区域整体范围的生态风险防御,已成为规划调控变革的内在需求。但建筑学等单一学科探索,难以有效应对城市-区域之间跨尺度、多要素的生态复杂性议题。通过国际经验检讨,从人地耦合系统的复杂性视角出发,立足于理论基础模型构建、区域生态风险辨识和规划方案绩效评估等3个基本模块,提出一种遵循“城市空间增长态势-资源环境压力变化-生态系统风险辨识-规划方案绩效评估”逻辑的方法模型,旨在改善城市规划实践中的区域生态风险防御能力。     

预先危险性分析在施工安全管理中应用

在安全管理过程中 ,预先危险性分析方法对工程项目的施工安全状况给以预先分析 ,并进而对其危险程度给以评价。此方法对预防安全事故的发生 ,以及建筑施工安全检查与评价提供了新思路     

燃烧、爆炸危险品分级程序的建立及验证

分析了联合国关于危险货物运输制定的分级程序及美国国防部关于弹药和炸药危险品的分级程序,结合火炸药特别是当前高能固体推进剂的特点,以及火炸药及制品在制造、运输、储存和使用中所存在的状态,建立了科学的、系统的、适合我国国情并与国际接轨的燃烧、爆炸危险品危险性分级程序和试验方法;针对典型R-2H、FG20推进剂和不敏感AFX-757炸药,利用本文建立的“燃烧、爆炸危险品危险性分级程序和试验方法”进行了危险性分级,结果与国外文献报道的危险性级别相一致。     

基于未确知的化工系统HAZOP分析

基于传统的HAZOP分析存在量化困难的缺陷,提出未确知数-HAZOP分析模型,该模型不仅解决传统HAZOP分析的存在的问题,还可以根据专家经验程度的不同整合专家给出的原因事件的概率区间值。文章利用该模型对运行过程中的化工装置进行了定性定量的分析。未确知数-HAZOP的分析思想对于进行化工事故预防具有重要的意义。