压缩空气泡沫在长距离管路输送中压降的数值模拟

基于Fluent对压缩空气泡沫在长距离管道中的流动特性进行了数值模拟研究,将压缩空气泡沫近似为弥散流,采用Saplart-Allmaras模型模拟了不同管径下压缩空气泡沫以及不同泡沫原液浓度的AFFF泡沫在长距离管道内的流动及压降变化。模拟结果表明,随着距离变化,各管径管道内压降均呈现线性变化,且随着压缩空气泡沫的流动,压降线性增大。管道管径对管内压降变化具有显著影响,管道直径越小,管道内压降越大;泡沫原液浓度对压降的影响较小,且压缩空气泡沫在长距离输送中的压力随距离线性衰减。将模拟结果与长距离输送的试验结果进行了对比,误差在10%以内。     

集成DEMATEL-ISM的古建筑火灾致因因素评价

为深入了解古建筑火灾事故致因因素,提高古建筑消防安全管理水平,基于事故致因理论,采用德尔菲法从人员、古建筑消防系统、古建筑防火能力、安全管理与环境五个方面确定18个古建筑火灾致因因素,并建立古建筑火灾事故评价指标体系。同时运用实验室决策分析法(DEMATEL)构建矩阵对古建筑火灾致因因素进行分析。一方面,通过原因度定量结果对古建筑火灾致因因素的属性进行分类,确定其属于火灾原因因素还是结果因素;另一方面,通过中心度指标评价古建筑火灾各个致因因素的重要程度。进而利用解释结构模型(ISM)将致因因素进行层级划分,构建5层3阶的多级递阶模型,分析致因因素间的耦合和交互关系。结果表明,古建筑火灾事故的发生是近邻原因、过渡原因及本质原因共同作用的结果,并针对这三方面确定古建筑火灾事故重点管控方向。同时,在古建筑消防安全管理中,应重点关注中心度较大的致因因素。     

Cybersecurity and dynamic operation in practice: Equipment impacts and safety guarantees

Though dynamic operation of chemical processes has been extensively explored theoretically in contexts such as economic model predictive control or even considering the potential for cyberattacks on control systems creating non-standard operating policies, important practical questions remain regarding dynamic operation. In this work, we look at two of these with particular relevance to process safety: (1) evaluating dynamic operating policies with respect to process equipment fidelity and (2) evaluating procedures for determining the parameters of an advanced control law that can promote both dynamic operation as well as safety if appropriately designed. Regarding the first topic, we utilize computational fluid dynamics and finite element analysis simulations to analyze how cyberattacks on control systems could impact a metric for stress in equipment (maximum Von Mises stress) over time. Subsequently, we develop reduced-order models showing how both a process variable and maximum Von Mises stress vary over time in response to temperature variations at the boundary of the equipment, to use in evaluating how advanced control frameworks might impact and consider the stress. We close by investigating options for obtaining parameters of an economic model predictive control design that would need to meet a variety of theoretical requirements for safety guarantees to hold. This provides insights on practical safety aspects of control theory, and also indicates relationships between control and design from a safety perspective that highlight further relationships between design and control under dynamic operation to deepen perspectives from the computational fluid dynamics and finite element analysis discussions.     

Structural equation model of the influence of noise annoyance on miners’ unsafe behavior in coal mines

Miners' unsafe behavior (UB) is the main cause of coal mine accidents. Previous research has suggested that excessive noise in tunnels impacts miners' temperaments and safe production behavior. To explore the influence of noise on UB, four different dimensions of noise annoyance were identified: cognitive, emotional, communication, and physical mechanism annoyance. The coal mine noise annoyance scale, miners' unsafe behavior intention (UBI) scale, and miners’ UB scale were developed according to different dimensions. In the first survey, a total of 200 questionnaires were distributed in the two coal mines, and 193 valid questionnaires were recovered. Exploratory factor analysis was conducted, and invalid items were removed according to the analysis results to form the final scale. Then, 500 final scales were distributed in two Chinese coal mines, and 482 valid questionnaires were collected. Confirmatory factor analysis was conducted by collating the data of the second questionnaire. Based upon the structural equation model (SEM), the SEM of the influence of noise annoyance degree on UB and the path analysis with latent variable path analysis with the latent variables (PA-LVs) mediating model of the effect of UBI on UB were established, and the path coefficients with fitting data of the model were analyzed. The results indicated that the four dimensions of coal mine noise annoyance had a strong positive impact on UB, which was reduced by less noise annoyance. In addition, the Bootstrap method was used to verify the mediating method among the four dimensions of noise annoyance, cognitive annoyance, emotional annoyance, with communication annoyance indirectly affecting UB through UBI. The research results provide theoretical support for reducing the UB of miners and improving coal mine safety levels.     

Risk assessment of safety level in university laboratories using questionnaire and Bayesian network

Accidents in university laboratories not only create a great threat to students’ safety but bring significant negative social impact. This paper investigates the university laboratory safety in China using questionnaire and Bayesian network (BN) analysis. Sixteen influencing factors for building the Bayesian net were firstly identified. A questionnaire was distributed to graduate students at 60 universities in China to acquire the probability of safe/unsafe conditions for sixteen influencing factors, based on which the conditional probability of four key factors (human, equipment and material, environment, and management) was calculated using the fuzzy triangular theory and expert judgment. The determined conditional probability was used to develop a Bayesian network model for the risk analysis of university laboratory safety and identification of the main reasons behind the accidents. Questionnaire results showed that management problems are prominent due to insufficient safety education training and weak management level of management personnel. The calculated unsafe state probability was found to be 65.2%. In the BN analysis, the human factor was found to play the most important role, followed by equipment and material factor. Sensitive and inferential analysis showed that the most sensitive factors are personnel incorrect operation, illegal operation, and experiment equipment failure. Based on the analysis, countermeasures were proposed to improve the safe management and operation of university laboratories.     

城市电力供应系统公共安全风险评估体系及应用

城市电力供应系统与城市公共安全关系紧密，文章分析了导致城市电力供应系统故障或事故的主要风险因素、事故类型及其风险程度，建立了城市电力供应系统公共安全风险评估体系。利用建立的风险评估体系，对某市电力供应系统的安全性进行了风险评估，同时验证了该体系在城市电力供应系统风险评估中的良好适用性。     

砒霜生产化工厂危险废物处置工程设计

通过对砒霜生产化工厂原场址废渣及污染场地调查的基础上,进行了处置方案比选及技术经济比较,确定了就地安全填埋的处置方案。根据区域性危险废物集中安全填埋场的设计经验,本工程采用先进的HDPE双层防渗的安全填埋方式,并设置了雨水分流系统、渗滤液收集系统、封场处理和填埋气体导排系统,整个场区布置合理,对周围环境的影响小,投资少,取得了良好的社会效益和环境效益,并对危险废物处理处置工程设计中应注意的问题提出了建议。     

人行横道危险时段的灰色聚类评价研究

人行横道是人车冲突的焦点地带,以行人违规率(RTI)为评价指标,采用灰色聚类的评价方法,对人行横道的安全状况进行分级评价,然后对单条人行横道的不同时间段的安全状况进行评价,找出危险时段.     

桥梁安全综合评价体系构建及重心法评价研究

目前桥梁安全综合评价研究并不成熟,在分析了桥梁安全综合评价应该考虑的主要因素的基础上,提出并确立了桥梁安全综合评价体系.探讨了应用模糊重心决策法进行桥梁安全综合评价的实现过程,为桥梁安全管理人员和安监部门理性决策提供理论依据.     

某公司食堂施工过程危险性分析及对策措施

我国大多建筑施工企业目前的安全管理只局限于对施工现场的检查和整改工作,而对施工现场的整体安全性缺乏分析和有效的监控,目前安全评价技术在建筑业的运用并不成熟.运用科学的安全评价方法,对建筑施工危险性进行系统分析和研究,可以补充、完善和指导施工现场的安全管理工作.