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921.
922.
Peili Zhang Yang Du Yi Zhou Sheng Qi Songlin Wu Jiafeng Xu 《Journal of Loss Prevention in the Process Industries》2013,26(6):1279-1284
In order to investigate the effects of branch tunnels on explosion propagation, experiments were performed in five different configuration tunnels (straight configuration and configurations with 1 branch, 2 branches, 3 branches and 4 branches). Pressure and flame transducers were used to record the history of the pressure development and track the velocity of the flame front. It was shown that the branch tunnels had ability to enhance the maximum overpressure, rate of overpressure rise, and deflagration index (KG) of the gasoline–air mixture explosion due to the turbulence induced by the branch tunnels. The overpressure rise rate and KG of the explosion increased as a function of the number of branch tunnels. Experiments also showed that the maximum flame speed increased as the branch number increasing from 0 to 3 due to the enlargement of turbulence induced by the branch tunnels. However, an increase of branch number did not always lead to an enhancement of flame speed because the heat loss was intensified resulting from the increase of flame surface caused by the branch tunnels. When the number of branch tunnels exceeded 3, the maximum flame speed dropped. 相似文献
923.
应用模糊数学系统聚类方法对陕西1949~1990年自然灾害造成的人口死亡、房屋倒塌和农田成灾面积进行了聚类分析,划分出相似成灾年份及相应损失指标,同时通过总损失价值计算进行了逐年损失等级划分,建立了各级等级标准和灾害年景序列。 相似文献
924.
山东新汶矿业集团翟镇煤矿通过不断引进、消化和吸收国内外先进生产技术,走科技创新之路,这个昔日饱受顶板破碎干扰、生产条件复杂的大型矿井在短短几年的时间内实现了采掘机械化、辅助自动化、控制智能化,先后有136项科技项目首开国内先河,其中32项达到了国际先进水平。为推动“科技兴矿”战略的实施,翟镇煤矿采取了一系列有效措施: 相似文献
925.
杜卓勋 《湖南环境生物职业技术学院学报》2001,7(2):49-50
针对“极限”概念提出了一些见解,并从理论上描述和给出了“极限”的精确定义,从该定义出发,更有助正确理解和掌握“极限”的内在含义。 相似文献
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Microbial polyhydroxyalkanoates (PHAs) have been extensively studied as environmentally friendly biodegradable thermoplastics. The major obstacle to wide acceptance of PHAs is their high price, mainly attributed to the costs of raw materials and polymer recovery. A large amount of organic solids are discarded from food production and consumption and may be used as carbonaceous raw materials for production of PHAs. A novel technology was investigated at bench-top scale to produce PHAs from food scraps. The harvested cell mass had a high PHA content (72.6% of dry cell mass), the same as obtained from pure glucose and organic acids. The organic solid was first digested in an acidogenic reactor in which about 60% solid was converted to fermentative products, including short-chain fatty acids. The four major acids were acetic, propionic, butyric, and lactic acids at concentrations of 6, 2, 27, and 33 g/L, respectively. The acids were transported through a membrane barrier via molecular diffusion to an airlift bioreactor, where the acids were utilized by an enriched culture of Ralstonia eutropha for PHA synthesis. Purification of fermentative acids was not performed in this molecular diffusion–based integration of acidogenesis and polymerization. By using a dialysis membrane as the barrier, the dry cell mass concentration and PHA content reached 22.7 g/L and 72.6%, respectively. The PHA was a copolymer of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with 2.8 mole % of hydroxyvalerate. 相似文献
929.
井下运输系统是一个环节复杂、影响安全因素甚多的庞大系统。运输事故是煤矿井下常见的多发性事故。造成事故的原因是人、机、环境的缺陷。根据人- 机- 环境系统工程的理论,对井下运输系统的安全性进行了初步的探讨,为掌握事故发生的规律和提高系统的安全性,试图提供一种分析的思路与方法 相似文献
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