通风机站风流间相互影响阻力特性研究*

为研究双风机并联机站进口、出口风流相互影响的机站局部阻力特性,构建机站通风局部阻力计算的数学模型,同时运用相似原理建立双风机并联通风机站实验模型,并佐以数值模拟对比验证,分析计算不同风机间距的无量纲数A、不同扩散器结构参数条件下的综合影响系数Kc。结果表明:A与Kc具有二次函数关系,且存在较优的A,使得Kc值最小;Kc值随着L/Df增加而线性减小。研究结果有利于Kc的选取,为高效率通风机站结构设计提供技术及数据支撑。     

挥发性油藏回注气井控因素分析及措施

文章明确了挥发性油藏天然气回注井控的安全环保关键因素;量化了低渗挥发性油藏天然气回注注入能力,确定注入端各节点安全生产压力分布,攻关相关配套工艺设备,实现安全有效注入;开展室内实验和PVT相态拟合,分析注天然气后天然气和原油性质变化规律,创新非混相驱组分数值模拟参数优化方法,开展带人工压裂裂缝的组分数值模拟,精准确定压力场分布,降低计量及监测不准带来的安全隐患;明确注气井气窜影响因素,优化注采参数,抑制油井气窜,降低生产风险,实现井控安全情况下的天然气驱环保高效开发。     

Characteristics of ride share services for older adults in the United States

Introduction: Safe and accessible transportation options are important for older adults’ health, safety, mobility, and independence. Ride share services may promote older adult health and well-being. This is the first study that describes ride share services available to older adults (65+ years) in the United States, including factors that may affect use of services. Methods: We analyzed secondary data from two research and administrative databases provided by ITNAmerica, a national non-profit transportation service for older adults: ITNRides, which tracks information on older adults who used ITN in 29 locations across the United States from 1996 to 2019, and Rides in Sight, the largest national data source on ride share services for older adults. We conducted a literature review, and telephone interviews with nine key informants representing ride share services, referral services, and other organizations. We offer a conceptual framework describing factors that may affect older adults’ use of ride share services. Results: This study identified 917 non-profit ride share services and eleven for-profit ride share services available for older adults in the United States as of August 2018. Services varied by corporate structure, location, use of technology, and business model. The majority of non-profit services served primarily older adults, while the for-profit services served primarily younger adults. Riders from one multi-site non-profit service had a median age of 82. Use of ride share services is affected by individual needs and preferences; social conditions; and business and policy factors. Conclusion: Ride share services may offer a promising alternative to driving for older adults and may help to address negative health consequences associated with driving cessation. Practical applications: These findings may help policy makers, practitioners, and other stakeholders understand older adults’ needs related to use of ride share services in order to offer solutions that prioritize public health and safety.     

Moving FOCUS – The Fire Service Organizational Culture of Safety survey – From research to practice

Introduction: FOCUS, the Fire Service Organizational Culture of Safety survey, has evolved from a research to practice enterprise within the United States fire and rescue service. The FOCUS tool was developed through a FEMA Assistance to Firefighters Research & Development grant. Then it moved to practice in the field. To date over 35,000 firefighters have participated. A current FEMA Fire Prevention & Safety grant can support FOCUS assessment in up to 1,000 fire departments, with the potential of nearly 120,000 respondents. With each funding cycle, the goal of the FOCUS program is to grow and measure its research to practice impact. Methods: We describe how FOCUS safety culture results are disseminated to fire service stakeholders. By utilizing customized reports and a training curriculum we demonstrate how FOCUS is moving research to practice by: (1) illustrating how survey results can be delivered effectively to practitioners, (2) providing examples of how fire departments are using results, and (3) sharing the reactions of the fire service to the FOCUS instrument, reports, and our flagship data training curriculum – Culture Camp. Results' Conclusions: Qualitative and quantitative data are analyzed to demonstrate the impact and acceptance of the FOCUS report and Culture Camps. Stakeholders reflect on the report and the experience of having quantitative safety culture data. Culture Camps are evaluated qualitatively and quantitatively using a matching game exercise, pre/post-test, a fire department teach back, and a Qualtrics evaluation. Practical Applications: Traditionally, the fire service has focused on reducing negative safety outcomes. FOCUS is helping shift their attention further upstream in the prevention pathway through the measurement of important organizational outcomes. The research to practice evolution of the FOCUS program may hold utility for other occupational groups when considering how to steadily move occupational health and safety research to practice in the field for measurable impact.     

System safety assessment using safety entropy

Safety assessment has a primary role in hazardous operations. Most studies on safety assessment focus on risk and accident modeling, in which safety is absent. These top-down methods are highly dependent on the occurred accidents to establish accidental scenarios, which may make the assessment approach lagging behind the evolving modern systems. Moreover, this “special to general” logic is scientifically suspect in safety assessment. There is a call for the development of safety assessment methods in the presence of system safety to complement risk-focused safety analysis. These methods should provide a framework based on a bottom-up approach to examine system safety from the operational perspective. This paper has attempted to provide a potential solution. In particular, a novel concept of safety entropy is proposed to integrate with The Functional Resonance Analysis Method (FRAM), which is used to form the qualitative understanding of a system. A formula consisted of safety entropy, functional conformability, and system complexity has been established to determine the spontaneity of the safety state-changing process. The proposed method is applied to the safety assessment of a propane feed-control system. The results show the applicability of the method. Nevertheless, the model still needs to be further improved to fulfill better support for safety-related decision problems.     

Study on explosion risk of aluminum powder under different dispersions

This paper mainly studied the influence of particle size distribution on the explosion risk of aluminum powder under the span of large particle size distribution. The measurement was carried out with the 20 L explosion ball and the Hartmann tube. The statistical analysis was used to analyze the relevance between the parameters of explosion risk and the particle size parameters. Test results showed that with the increase of particle size, the sensitivity parameter increases and the intensity parameter deceleration decreases. The effect of particle size change on MEC and MIE of small particle size aluminum powder is relatively small but greater impact on Pm and (dP/dt)m. The small particle size components greatly increasing the sensitivity of the explosion and accelerating the rate of the explosion reaction; while the large particle size component contributes to the maximum explosion pressure. D_3,2 particle size dust determines the risk of aluminum powder explosion.     

Risk assessment and risk reduction of an acrylonitrile production plant

Reducing accident occurrence in petrochemical plants is crucial, thus appropriately allocating management resources to safety investment is a vital issue for corporate management as international competition intensifies. Understanding the priority of safety investment in a rational way helps achieve this objective.In this study, we targeted an acrylonitrile plant. First, Dow Chemical's Fire and Explosion Index (F&EI) identified the reaction process as having the greatest physical risk. We evaluated the severity of accidents in the reaction process using the Process Safety Metrics advocated by the Center for Chemical Process Safety (CCPS); however, this index does not express damages a company actually experience. To solve this problem, we proposed a new metric that adds indirect cost to CCPS metrics. We adopted fault tree analysis (FTA) as a risk assessment method. In identifying top events and basic events, we attempted to improve the completeness of risk identification by considering accidents from the past, actual plant operation and equipment characteristics, natural disasters, and cyber-attacks and terrorist attacks. Consequently, we identified the top events with high priority in handling because of serious accidents as fire/explosion outside the reactor, fire/explosion inside the reactor, and reactor destruction. The new CCPS evaluation index proposed in this study found that fire and explosion outside the reactor has the highest severity. We considered the creation of the fault tree (FT) diagram of the top event, estimating the occurrence probability, and identifying the risk reduction part and capital investment aimed at risk reduction. As an economically feasible selection method for risk reduction investment, using the difference in loss amounts before and after safety investments indicated investment priority.     

Characterization of Ti powders mixed with TiO2 powders: Thermal and kinetic studies

The fire and explosion risks of metal powders admixed with solid inertants have been extensively investigated for many years. However, it remains unclear why such solid mixtures have high potential fire and explosion risk even when mixed with high percentages of non-combustible solids. This paper investigates how to interpret these risks, from a microscopic perspective, with thermal and kinetic parameters including initial ignition temperature, mass unit exothermic energy, activation energy and risk index of spontaneous combustion. The results show that the initial ignition temperature based on TG (Thermogravimetry) analysis is related to ignition sensitivity, and increased with percentage of admixed solid inertant. The unit mass exothermic energy based on DSC (Differential scanning calorimetry) analysis is related to flame spread velocity. Activation energy and the risk index of spontaneous combustion can be used to explain the reactivity and spontaneous combustion hazard, respectively, of metal powders. We conclude that thermal and kinetic parameters may provide another way to describe the fire and explosion risk of combustible powders, especially for nano metal powders due to the laboratory safety in the normative tests for explosion parameter determination.     

微波、毫米波电磁材料特性及参数宽频带测试方法

讨论一种微波、毫米波电磁材料特性和参数宽频带测量方法——自由空间法。给出了该测量方法的测试原理和基于国产AV3630幅相接收机为基础的测试系统构成及系统扩频方法,论述了自由空间测试法需注意的关键技术问题。     

半导体企业的EHSMS评价体系研究

为了给员工提供安全、环保、健康的工作环境,半导体制造企业必须建立环境管理和职业健康安全管理体系(EHSMS).为此,评价EHSMS运行的有效性、完整性以及合法性就显得十分重要.本文在分析半导体企业污染物影响环境和健康基础上,建立了EHSMS评估体系.为了实施EHSM评估系统,方便半导体企业用户使用,提出了一套EHSM评价系统的计算机软件解决方案.