Analysis of the experimental results of the initiation of detonation in short tubes with kerosene–oxidizer mixtures

The paper describes the experimental investigation of detonation initiation in a mixture of kerosene–oxidant in a short test tube. Various mixtures of oxygen and nitrogen were used as an oxidant, from pure oxygen to the composition of air. The goal of the study was to determine the minimum diameter of the tube and the minimum level of energy needed for the direct initiation of detonation. As a result of the measurements the pressure courses were obtained for two kinds of cases: with and without (only shock waves) of fuel injection. The results of both kinds of measurements were compared, providing information about the initiation of detonation in a fuel–oxidizer mixture. Brief analyses of the results for different initiators and different oxidizers were performed and compared with the shock wave and Chapman–Jouget velocity.     

Comparative assessment of the explosion characteristics of alcohol–air mixtures

Explosion characteristics of five alcohol–air (ethanol, 1-butanol, 1-pentanol, 2-pentanol and 3-pentanol) mixtures were experimentally conducted in an isochoric chamber over wide ranges of initial temperature and pressure. The effect of temperature and pressure on the different explosion behaviors among these alcohols with various structures were investigated. Results show that the peak explosion pressure is increased with the decrease of temperature and increase of pressure. Maximum rate of pressure rise is insensitive to the temperature variation while it significantly increases with the increase of initial pressure. Among the 1-, 2-, and 3-pentanol–air mixtures, 1-pentanol has the highest values in peak explosion pressure and maximum rate of pressure rise and 2-pentanol gives the lowest values at the initial pressure of 0.1 MPa. These differences tend to be decreased with the increase of initial pressure. Among the three primary alcohol–air (ethanol, 1-butanol and 1-pentanol) mixtures, a similar explosion behavior is presented at the lean mixture side because of the combined effect of adiabtic temperature and flame propagation speed. At the rich mixture side, 1-pentanol gives the highest values in peak explosion pressure and maximum rate of pressure rise and ethanol gives the lowest values. This phenomenon can be interpretated from the combining influence of heat release and heat loss, since the flame speeds of ethanol-, 1-butanol-, 1-pentanol–air mixtures are close at rich mixture side.     

A Contribution to the Study of the Antidust Respirators’ Real Performance

In most industrial enterprises, hazardous factors are present in quantities exceeding permissible levels. Such a situation requires using antidust respiratory protection. It has been suggested, however, that filters for respirators are not assessed properly and that lab results might not be related to real filtering efficiency in industry. This article contains test results of some commercially available filtering half-masks, including the effect of loading with real dust, high humidity, high temperature, and a combination of loading with dust and high humidity on the half-masks’ performance. The results show that the effect of these factors is considerable and that a combination of loading with silica dust and exposing to high humidity can cause a complete loss of performance.     

Risk and characteristics analysis of the flow-induced vibration of the dip tube in opposed multi-burner gasifier

The vibration of dip tube in multi-burner gasifier changes the stress at the connection, causing flange seal failures and high temperature gas erosions with heavy economic losses and industrial accidents. This work aims to reveal the dip tube vibration mechanism, with special focus on obtaining the effect of operational parameters on the fatigue damage and long-term stable operation of gasifiers. A three-dimensional numerical simulation of the water-scrubbing cooling chamber was conducted to obtain the excitation source in the flow field. Then a FSI (fluid-structure interaction) transient dynamics simulation was carried out to investigate the vibration characteristics. Two major flow forms were found: a vertical annular flow near the dip tube outlet in the water-scrubbing cooling chamber; and a gas-liquid coupled flow caused by the syngas entrained the liquid. These two unstable multiphase flow forms exerted an energy excitation on the dip tube, resulting in a self-excited flutter. The dip tube vibration was similar to the first mode of a cantilever beam. The peak frequency was less affected by the initial liquid level and the syngas stream inlet velocity, which was close to its own first natural frequency. Note that, the alternating load generated by vibration may cause fatigue damage, which needs to be specifically considered in the design and manufacturing process of opposed multi-burner gasifier.     

Loyal rebels? A test of the normative conflict model of constructive deviance

Constructive deviance is a voluntary behavior that violates organizational rules but is conducted with honorable intentions to benefit the organization or its stakeholders. Despite emerging interest in this behavior, the antecedents of constructive deviance remain unclear, with particular ambiguity concerning the relationship between organizational identity and constructive deviance. In this article, we address this ambiguity with the normative conflict model, which posits that organizational identity drives constructive deviance in the workplace only when people perceive normative conflict with organizational rules. In Studies 1a and 1b, we develop and validate a measure of normative conflict. In Study 2, we conduct a preliminary test of the model with employed students and find that identity is positively related to constructive deviance only when normative conflict is high. In Study 3, we replicate and extend the model to show that the moderating effect of normative conflict is mediated by experienced psychological discomfort and that organizational identity is positively related to constructive deviance among working adults only when discomfort is high. In total, our findings demonstrate the utility of the normative conflict model for explaining when constructive deviance is mostly likely to occur in the workplace.     

Learning lessons from tunnel accidents – Recommendations in support of the implementation of Article 15 on Reporting of the EU Directive 2004/54/EC

Tunnels in the trans-European road network (TEN) facilitate the transport of persons and goods on European roads. Following a series of major tunnel accidents European Union Directive 2004/54/EC was adopted to support the achievement of uniform and high tunnel safety levels. With future accident prevention and mitigation in mind and in support of the effective implementation of Article 15 on Reporting of the Directive we outline a procedure for learning lessons and discuss every step in the process with specific regard for its implications on Article 15. This includes accident investigation, reporting, data collection and analysis, learning lessons and their implementation. The realization that validated information on tunnel accidents is not easily available or accessible, or suffers from a lack of detail or accuracy fed into the development of a data-collection template. By its very nature the template development also guided the formulation of key recommendations for accident investigation and reporting as the main information source. In addition, key recommendations on data analysis, learning lessons and implementation were also made to assist the actors responsible for reporting or sharing information under the EU Directive.     

Learning from incidents – A method for assessing the effectiveness of the learning cycle

This paper describes a method for assessing the effectiveness in the steps of the learning cycle: the 1st loop with reporting – analysis – decision – implementation – follow-up, and the 2nd loop on an aggregated basis. For each step, the dimensions considered the most relevant for the learning process (scope, quality, timing and information distribution) and for each dimension the most relevant aspects (e.g. completeness and detail) were defined. A method for a semi-quantitative assessment of the effectiveness of the learning cycle was developed using these dimensions and aspects and scales for rating. The method will give clear indications of areas for improvement when applied. The results of the method can also be used for correlation with other safety parameters, e.g. results from safety audits and safety climate inquiries. The method is intended to be used on a sample of the broad range of incidents normally seen in process industry companies. The method was tested on a two-year incident reporting material from six companies from various types of process industries. It was found that the method and the tools worked very well in practice. The results gave interesting insights into the effectiveness of learning from the incidents.     

Bund overtopping — the consequence of catastrophic tank failure

The Health and Safety Executive (HSE) has considerable interest in predicting the consequence of releases of hazardous liquids from storage tanks (HSE, 1998), because of its responsibilities as a statutory adviser to local planning authorities on the siting of hazardous installations and on the control of development in their vicinity, and because of its responsibilities alongside the Environment Agencies as the Competent Authority in the assessment of COMAH safety reports. As a result, HSE has commissioned a number of studies, including: experimental studies of the behavior of liquid spills (Lee and Kountouris, 1992, Skitt and Wheeler, 1989, Bentinck and Crow, 1991, Clark and Savery, 1993, Law and Johnskareng, 1994, Ruddle and Widowson, 1985, Ruddle and Elms, 1985, Cleaver, Cronin, Evans and Hirst, 2001), a review of overtopping data and theoretical models used to study liquid flow (Thyer & Jagger, 1997), the characterization of the profile of the leading edge of the spreading liquid (Thyer, MacMillan, & Jagger, 1999), and the development and use of complex mathematical models to predict overtopping fractions and liquid spill behavior (Daish et al., 1998, Ivings and Webber, 2001).This paper summarizes the consequences of catastrophic tank failure, the current position on the availability of liquid spill data for model validation, and indicates how such data may be used to predict the often considerable fraction of liquid that could overtop retaining bunds around real tanks.     

Testing the validity of the “value of a prevented fatality” (VPF) used to assess UK safety measures

The “value of a prevented fatality” (VPF), the maximum amount that it is notionally reasonable to pay for a safety measure that will reduce by one the expected number of preventable premature deaths in a large population, is published by the UK Department for Transport (DfT). The figure, updated for changes in GDP per head, is used by the DfT, the Health and Safety Executive and other UK regulatory bodies as well as very widely in the process, nuclear and other industries as the standard by which to judge how much to spend to reduce harm to humans. The paper tests the validity of the 1999 study on which the VPF is based and finds that that study fails numerous tests of its validity. It is concluded that there is no evidential base for the VPF that has been used for many years in the UK and is still in standard use today. Given the difficulties evident in the interpretation of survey results, an urgent re-appraisal is needed of alternative statistical methodologies that can allow robust regulatory and industry safety decision making and, vitally, give adequate protection to the UK public and to those working in the UK's transport, process, nuclear and other industries.     

Tired of innovations? Learned helplessness and fatigue in the context of continuous streams of innovation implementation

The business environment faced by contemporary organizations is highly uncertain and constantly changing. Thus, organizations have adopted and implemented a continuous stream of innovations to achieve sustainable growth and survival. Considering the demand for additional resources to implement innovations, the present study explores organizational conditions that may lead to innovation‐targeted burnout and fatigue among employees, which impede their active participation in a subsequent innovation. To this end, we propose a theoretical framework that elucidates the effects of previous innovations on the subsequent implementation behavior of employees. We identify two dimensions of the cognitive appraisal of previous innovations (i.e., intensity and failure) that shape employees' beliefs regarding innovations, such as innovation‐targeted helplessness, which ultimately results in innovation fatigue. Data collected from 84 managers and 397 employees of Chinese and Korean organizations prove the significant role of employee perceptions of previous innovations in shaping the innovation‐targeted helplessness and fatigue of employees, which ultimately affect employee behavior toward a subsequent innovation. The present conceptual and empirical analyses suggest that given continuous streams of innovation implementation, managers should carefully consider employee's perceptions of previous innovations (i.e., intensity and failure) for successful implementation of a subsequent innovation. Copyright © 2017 John Wiley & Sons, Ltd.     

Assessment of the effect of welding fumes on welders’ cognitive failure and health-related quality of life

Introduction. This study examined whether cognitive symptoms and health-related quality of life can be affected by welding fume exposure. Method. Participants consisted of welders (n?=?40) and welder assistants (n?=?25) from welding units as the exposed group, and office workers (n?=?44) as the non-exposed group. All participants were studied using ambient air monitoring and two types of questionnaires: the Cognitive Failures Questionnaire (CFQ) and the 36-item Short Form Health Survey (SF-36). Results. Welders and welder assistants were exposed to higher concentrations of all airborne metals than office employees, except for aluminum and chromium (p?p?M (SD)?=?54.84 (17.88)). The relationships between total CFQ score and the measured concentration of nickel at peak work rate was significant for welders. Conclusion. Cognitive symptoms and health-related quality of life were not related to the measures of welding fume exposure and further research should be performed to find other influencing factors.     

Pooled Analysis of Two Swedish Case-Control Studies on the Use of Mobile and Cordless Telephones and the Risk of Brain Tumours Diagnosed During 1997–2003

Here we present the pooled analysis of 2 case–control studies on the association of brain tumours with mobile phone use. Use of analogue cellular phones increased the risk for acoustic neuroma by 5%, 95% confidence interval (CI) = 2-9% per 100 hrs of use. The risk increased for astrocytoma grade III—IV with latency period with highest estimates using >10-year time period from first use of these phone types. The risk increased per one year of use of analogue phones by 10%, 95% CI = 6-14%, digital phones by 11%, 95% CI = 6-16%, and cordless phones by 8%, 95% CI = 5-12%. For all studied phone types OR for brain tumours, mainly acoustic neuroma and malignant brain tumours, increased with latency period, especially for astrocytoma grade III—IV.     

Study of the spontaneous ignition of stoichiometric tetrafluoroethylene–air mixtures at elevated pressures

The Ignition Temperature (IT) of stoichiometric tetrafluoroethylene–air mixtures on hot walls was determined in a 3-dm³-reactor. Tests at elevated pressure conditions were performed, namely at 5, 15 and 25 bar(a), showing a decrease of the IT with the initial pressure. Furthermore, the measured ignition temperatures of stoichiometric tetrafluoroethylene–air mixtures were lower than the ignition temperatures required for the decomposition pure tetrafluoroethylene (Minimum Ignition Temperature of Decomposition, MITD) reported in previous works.Equations from the Semenov thermal explosion theory on spontaneous ignition were used to identify approximate combustion kinetics of tetrafluoroethylene from the experimental results. The determined kinetics was used for the prediction of the IT of stoichiometric tetrafluoroethylene-air by simplified calculation methods. A very good agreement with the experimental results was observed.     

Prevalence of Musculoskeletal Disorders at Workplaces in the People’s Republic of China

This paper presents 2 musculoskeletal disorders questionnaire surveys in 10 different Chinese occupational groups. Data collected from 1,603 workers using a modified Nordic musculoskeletal disorders symptom questionnaire showed that the 12-month prevalence of musculoskeletal disorders, particularly in the low back and shoulder-neck regions, was high at many Chinese workplaces. Significant differences existed between occupational groups. Assembly workers usually had higher neck-shoulder complaints compared to workers in most other occupations. However, the nature of assembly seemed also to influence the prevalence rate. Workers at a cassette recorder and a TV set assembly plant appeared to have more neck complaints compared with a group of thermos flask assemblers.     

Study of the explosion parameters of vapor–liquid diethyl ether/air mixtures

The knowledge of the vapor–liquid two-phase diethyl ether (DEE)/air mixtures (mist) on the explosion parameters was an important basis of accident prevention. Two sets of vapor–liquid two-phase DEE/air mixtures of various concentrations were obtained with Sauter mean diameters of 12.89 and 22.90 μm. Experiments were conducted on vapor–liquid two-phase DEE/air mixtures of various concentrations at an ignition energy of 40.32 J and at an initial room temperature and pressure of 21 °C and 0.10 MPa, respectively. The effects of the concentration and particle size of DEE on the explosion pressure, the explosion temperature, and the lower and upper flammability limits were analyzed. Finally, a series of experiments was conducted on vapor–liquid two-phase DEE/air mixtures of various concentrations at various ignition energies. The minimum ignition energies were determined, and the results were discussed. The results were also compared against our previous work on the explosion characteristics of vapor–liquid two-phase n-hexane/air mixtures.     

Is the effect of quantified road safety targets sustainable?

Recent studies have shown that the setting of road safety targets is associated with a substantial reduction in road fatalities in the short-term. Although such targets may not themselves be responsible for the reduction in fatalities, they serve as a useful measure of the intention and commitment of road authorities to formulate timely road safety measures that lead to the achievement of the target. A quantified target is regarded as one of the key components of a road safety strategy. However, few studies have examined the degree of commitment and attention of road authorities to such targets in the long-term. In this study, we revisit the effectiveness of the quantified road safety targets set by the Organisation for Economic Co-operation and Development (OECD) countries, but with a different method, time scale, and group of comparison countries. We not only evaluate the associations between quantified targets and road fatality levels, but also measure the changes in the time-series trends in road fatalities over the long-term. The results indicate that all seven treatment countries analyzed experienced desirable changes in the time-series trend in road fatalities during the period under study, which implies an increase in road safety improvement over time.     

Do the designated drivers of college students stay sober?

PROBLEM: By numerous accounts, alcohol abuse is considered the number one drug problem facing young people today. Alcohol consumption and its negative consequences, especially those due to drinking and driving, continue to have devastating effects on the college student population. METHOD: This field study examined the blood alcohol concentration (BAC) levels of male and female designated drivers (DD), non-DD, and their respective passengers as they were leaving drinking establishments in a university town. Also investigated were the effects of group size and gender on DD use. RESULTS: A 2 Gender x 2 Driver type (DD vs. non-DD) analysis of variance (ANOVA) for BAC indicated significant main effects for Gender and Driver type, with higher BAC for men and non-DD (p's<.001). A significant Gender x Driver type interaction (p<.05) was primarily due to female DD having lower BAC than male DD. In addition, larger groups were more likely to have a DD. IMPACT ON INDUSTRY: Results indicate that the success of DD programs may be influenced by group size and a DD's gender. While larger groups are more likely to have a DD, students riding home with a male DD may still be at risk for the negative consequences of drunk driving.     

Exposure-based assessment of the effectiveness of Michigan’s graduated driver licensing nighttime driving restriction

The objective of the study is to assess the effectiveness of Michigan’s graduated driver licensing (GDL) program in terms of nighttime driving restriction. The research uses the quasi-induced exposure technique to capture and represent the exposure and accident risk change of the impacted driver groups due to the implementation of the GDL program. Six years of Michigan accident data were used, including three years before the GDL implementation and three years after. The effectiveness of Michigan’s GDL program in terms of nighttime driving is reflected in several dimensions: for the impacted drivers (16- and 17-year-olds), there is a significant reduction of exposure compared to the reference group and a decrease in the relative accident involvement ratio (thus a reduced accident risk); and examination of time of day distributions of impacted teenage drivers shows that there is a conspicuous percentage drop of impacted teenage drivers at the point where the nighttime curfew starts. With the implementation of the GDL program, the affected group tends to drive increasingly more in the several hours prior to the restricted time period to avoid violating the curfew law. As opposed to the traditional exposure measurements such as population or licensed drivers, quasi-induced exposure technique has the capability of depicting the accident propensity and quantifying exposure change from different age groups.