Effects of particle thermal characteristics on flame microstructures during dust explosions of three long-chain monobasic alcohols in a half-closed chamber

To reveal clearly the effects of particle thermal characteristics on flame microstructures during organic dust explosions, three long-chain monobasic alcohols, solid at room temperature and similar in physical-chemical properties, were chosen to conduct experiments in a half-closed chamber. In the experiments, the dust materials were dispersed into the chamber by air to form dust clouds and the hybrids were ignited by an electrical spark. A high-speed optical schlieren system was used to record the flame propagation behaviors. A fine thermocouple and an ion current probe were respectively used to measure the flame temperature profile and the reaction behaviors of the combustion zone. Based on the experimental results, combustion behaviors and flame microstructures in dust clouds with different thermal characteristics were analyzed in detail. As a result, it was found that the dust flame surfaces were completely covered by cellular structures that significantly increased the flame frontal areas. Flame propagated more quickly and the number of the cellular cells increased as increasing the volatility of the particles. On the contrary, maximum temperature and the thickness of the preheated zone decreased as increasing the volatility of the particles. According to the ion current profile, the particles in the preheat zone were pyrolyzed to intermediate radicals and the radicals' fraction in the higher volatile dust flame was higher than that in the lower volatile dust flame.     

A product analysis-based study on the mechanism of inflammable gas explosion suppression

To study the mechanism of the suppressing effect of Expanded Aluminium (EA) on the premixed gas explosion, premixed methane-air and propane-air gases were undergone explosion reaction in the presence of EA in a self-designed closed pipeline with the overpressures and the compositions, rates and sensitivities of products analyzed. The results showed that the 9.5% methane-air and 5% propane-air explosions produced peak pressures decreased by 79.3% and 65.6%, and residual methane and propane contents increased by 270% and 560% respectively than without EA. In addition, the results revealed that the explosions of propane in the presence of EA produced less methane and carbon oxides contents, but more ethylene and propylene contents. The simulation showed that H, O, and OH are the key factors affecting the rate of products. The product compositions, together with other parameters, suggested that EA decreased temperature, inhibited chain initiation and propagation reaction, but facilitated chain termination reaction by advancing and accelerating the gas phase and wall destruction reaction of radicals, especially collisions and concentration of key free radicals. This new research method based on the analysis of explosion products can be used for in-depth research into gas explosion features and shed light on the suppressing mechanism of EA in flammable gas explosion.     

A hybrid decision-making approach based on FCM and MOORA for occupational health and safety risk analysis

IntroductionWith the development of industries and increased diversity of their associated hazards, the importance of identifying these hazards and controlling the Occupational Health and Safety (OHS) risks has also dramatically augmented. Currently, there is a serious need for a risk management system to identify and prioritize risks with the aim of providing corrective/preventive measures to minimize the negative consequences of OHS risks. In fact, this system can help the protection of employees’ health and reduction of organizational costs. Method: The present study proposes a hybrid decision-making approach based on the Failure Mode and Effect Analysis (FMEA), Fuzzy Cognitive Map (FCM), and Multi-Objective Optimization on the basis of Ratio Analysis (MOORA) for assessing and prioritizing OHS risks. After identifying the risks and determining the values of the risk assessment criteria via the FMEA technique, the attempt is made to determine the weights of criteria based on their causal relationships through FCM and the hybrid learning algorithm. Then, the risk prioritization is carried out using the MOORA method based on the decision matrix (the output of the FMEA) and the weights of the criteria (the output of the FCM). Results: The results from the implementation of the proposed approach in a manufacturing company reveal that the score at issue can overcome some of the drawbacks of the traditional Risk Priority Number (RPN) in the conventional FMEA, including lack of assignment the different relative importance to the assessment criteria, inability to take into account other important management criteria, lack of consideration of causal relationships among criteria, and high dependence of the prioritization on the experts’ opinions, which finally provides a full and distinct risk prioritization.     

How certain are we about the certainty-equivalent long term social discount rate?

Theoretical arguments for using a term structure of social discount rates (SDR) that declines with the time horizon have influenced government guidelines in the US and Europe. The certainty equivalent discount rate that often underpins this guidance embodies uncertainty in the primitives of the SDR, such as growth. For distant time horizons the probability distributions of these primitives are ambiguous and the certainty equivalent itself is uncertain. Yet, if a limited set of characteristics of the unknown probability distributions can be agreed upon, ‘sharp’ upper and lower bounds can be defined for the certainty-equivalent SDR. Unfortunately, even with considerable agreement on these features, these bounds are widely spread for horizons beyond 75 years. So while estimates of the present value of intergenerational impacts, including the social cost of carbon, can be bounded in the presence of this ambiguity, they typically remain so imprecise as to provide little practical guidance.     

Hazard property classification of waste according to the recent propositions of the EC using different methods

Hazard classification of waste is a necessity, but the hazard properties (named “H” and soon “HP”) are still not all defined in a practical and operational manner at EU level. Following discussion of subsequent draft proposals from the Commission there is still no final decision. Methods to implement the proposals have recently been proposed: tests methods for physical risks, test batteries for aquatic and terrestrial ecotoxicity, an analytical package for exhaustive determination of organic substances and mineral elements, surrogate methods for the speciation of mineral elements in mineral substances in waste, and calculation methods for human toxicity and ecotoxicity with M factors.In this paper the different proposed methods have been applied to a large assortment of solid and liquid wastes (>1 0 0).Data for 45 wastes – documented with extensive chemical analysis and flammability test – were assessed in terms of the different HP criteria and results were compared to LoW for lack of an independent classification. For most waste streams the classification matches with the designation provided in the LoW. This indicates that the criteria used by LoW are similar to the HP limit values.This data set showed HP 14 ‘Ecotoxic chronic’ is the most discriminating HP. All wastes classified as acute ecotoxic are also chronic ecotoxic and the assessment of acute ecotoxicity separately is therefore not needed. The high number of HP 14 classified wastes is due to the very low limit values when stringent M factors are applied to total concentrations (worst case method). With M factor set to 1 the classification method is not sufficiently discriminating between hazardous and non-hazardous materials. The second most frequent hazard is HP 7 ‘Carcinogenic’. The third most frequent hazard is HP 10 ‘Toxic for reproduction’ and the fourth most frequent hazard is HP 4 “Irritant – skin irritation and eye damage”. In a stepwise approach, it seems relevant to assess HP 14 first, then, if the waste is not classified as hazardous, to assess subsequently HP 7, HP 10 and HP 4, and then if still not classified as hazardous, to assess the remaining properties.The elements triggering the HP 14 classification in order of importance are Zn, Cu, Pb, Cr, Cd and Hg. Progress in the speciation of Zn and Cu is essential for HP 14. Organics were quantified by the proposed method (AFNOR XP X30-489) and need no speciation. Organics can contribute significantly to intrinsic toxicity in many waste materials, but they are only of minor importance for the assessment of HP 14 as the metal concentrations are the main HP 14 classifiers. Organic compounds are however responsible for other toxicological characteristics (hormone disturbance, genotoxicity, reprotoxicity…) and shall be taken into account when the waste is not HP 14 classified.     

Plant blindness and the implications for plant conservation

Plant conservation initiatives lag behind and receive considerably less funding than animal conservation projects. We explored a potential reason for this bias: a tendency among humans to neither notice nor value plants in the environment. Experimental research and surveys have demonstrated higher preference for, superior recall of, and better visual detection of animals compared with plants. This bias has been attributed to perceptual factors such as lack of motion by plants and the tendency of plants to visually blend together but also to cultural factors such as a greater focus on animals in formal biological education. In contrast, ethnographic research reveals that many social groups have strong bonds with plants, including nonhierarchical kinship relationships. We argue that plant blindness is common, but not inevitable. If immersed in a plant‐affiliated culture, the individual will experience language and practices that enhance capacity to detect, recall, and value plants, something less likely to occur in zoocentric societies. Therefore, conservation programs can contribute to reducing this bias. We considered strategies that might reduce this bias and encourage plant conservation behavior. Psychological research demonstrates that people are more likely to support conservation of species that have human‐like characteristics and that support for conservation can be increased by encouraging people to practice empathy and anthropomorphism of nonhuman species. We argue that support for plant conservation may be garnered through strategies that promote identification and empathy with plants.     

Assessing Sustainability at Multiple Scales in a Rotational Bushmeat Hunting System

Abstract: Results of many studies show unsustainable levels of bushmeat hunting across West/Central Africa. Nevertheless, these results are usually derived from snapshot sustainability indices in which critical parameters are often taken from the literature. Simple, more informative tools for assessing sustainability are needed. We evaluated the impact of bushmeat hunting across a range of temporal, spatial, and taxonomic scales in a comparison of different measures of sustainability. Over 15 months in 2002–2004 in and around a village close to Equatorial Guinea's Monte Alén National Park, we collected data via a village offtake survey, hunter‐camp bushmeat‐consumption diaries, hunter interviews, and following hunters during hunts. We compared 2003 data with a previous offtake survey (1998–1999) and interview reports back to 1990. In the past 14 years, average distance from the village at which hunters operated remained constant, with hunters switching back and forth between long‐established camps, although trapping effort increased. In the past 5 years, overall offtake and number of active hunters did not change substantially, although catch per unit effort (CPUE) decreased slightly. Although the proportion of the two most commonly trapped species (Cephalophus monticola and Atherurus africanus) and gun‐hunted primates increased in the offtake, species presumably less robust to trapping decreased slightly. Apparent sustainability in economic terms may be masking gradual local extirpation of more vulnerable species before and during this study. Our results suggest that changes in prey profiles and CPUE may be the most accurate indicators of actual sustainability; these indices can be monitored with simple village‐based offtake surveys and hunter interviews to improve community management of bushmeat hunting.     

PLC控制系统在钢渣热焖工艺中的应用

利用PLC控制系统,实现在钢渣热焖工艺中的恒压供水和钢渣热焖定时定量喷水的自动控制要求,具有国际先进水平,取得了良好的经济效益、社会效益和环境效益.