Effects of thermal radiation heat transfer on flame acceleration and transition to detonation in particle-cloud hydrogen flames

The current work examines regimes of the hydrogen–oxygen flame propagation and ignition of mixtures heated by radiation emitted from the flame. The gaseous phase is assumed to be transparent for the radiation, while the suspended particles of the dust cloud ahead of the flame absorb and reemit the radiation. The radiant heat absorbed by the particles is then lost by conduction to the surrounding unreacted gaseous phase so that the gas phase temperature lags that of the particles. The direct numerical simulations solve the full system of two phase gas dynamic time-dependent equations with a detailed chemical kinetics for a plane flames propagating through a dust cloud. It is shown that depending on the spatial distribution of the dispersed particles and on the value of radiation absorption length the consequence of the radiative preheating of the mixture ahead of the flame can be either the increase of the flame velocity for uniformly dispersed particles or ignition either new deflagration or detonation ahead of the original flame via the Zel'dovich gradient mechanism in the case of a layered particle-gas cloud deposits. In the latter case the ignited combustion regime depends on the radiation absorption length and correspondingly on the steepness of the formed temperature gradient in the preignition zone that can be treated independently of the primary flame. The impact of radiation heat transfer in a particle-laden flame is of paramount importance for better risk assessment and represents a route for understanding of dust explosion origin.     

水、食品和人体中的~(234)U和~(238)U及其所致人体剂量

本文对近年文献报导中水、食品和人体中的~(234)U和~(238)U含量,比活度比值的调查结果,并估算出了人体所受的内照射剂量,作了评述,引用文献19篇,表格14张.     

微波法制取锯末活性炭及其吸附Cr~(6 )性能的研究

介绍了微波照射—氯化锌法(ZCMR)制取锯末活性炭的方法。用该法所制锯末活性炭处理含铬废水的结果表明,该锯末活性炭具有吸附容量大、过滤速度快、操作控制方便等优点,活性炭对铬的吸附容量是市售一级粉末活性炭的1.72倍,极限吸附量达21.5mg/g,过滤速度为市售活性炭的1.64倍。     

TiO2 photocatalytic antifungal technique for crops diseases control

Introduction N um erous studies have utilized a strong oxidizing pow der of TiO 2 photocatalysts to degrade aqueous or gaseous toxic organic pollutants for w ater purification, w astew ater treatm ent and air pollution control (Fujishim a et al., 2001; K …     

Effects of simulated acid rain on saplings of Pinus massoniana and Cunninghamia lanceolata

The effects of simulated acid rain with pH values of 6.63 (control, 4.5, 3.0, and 2.0 on saplings of Pinus massoniana and Cunninghamia lanceolate, were studied. The results showed that the pH of C.lanceolate, leaf sap and soil decreased as the acidity of rainfall increased. The acid rain with very low pH had significant effects on the photosynthetic rates per plant, but not on that of the per unit weight of dry leaves. The respiration rates of the two species were stimulated. Root and leaf boimass, but not stem biomass, were also reduced tremendously during a seven months period.     

基于人工神经网络的地面水环境质量评价模型

针对确定水体类别比较困难这一问题 ,引入人工神经元网络理论和思想 ,通过建立基于 BP人工神经网络模型 ,对地面水体环境质量进行评价。     

浅析室内环境安全问题及防治

人类进入新世纪,开始越来越认识到环境对我们的重要性,尤其对与我们朝夕相处的室内环境污染与安全问题.文章从环境安全的概念以及环境安全的重要性出发,提出了现在正被中国政府、社会和人们陪受关注的与人类健康和生命安全息息相关的室内环境安全问题,并从室内空气污染、噪声污染、电磁辐射污染、水污染、光污染、固本废物污染、房屋设计、选址等多方面多角度综述了室内环境污染问题及对人体产生的危害,并提出了相应的防治措施.     

云南省电磁辐射污染现状及其发展趋势分析

云南省电磁辐射污染源分布不均,以通讯行业最大.未来除通讯外,广播电视和交通电力的电磁辐射污染也会增     

Leaf area development, dry weight accumulation and solar energy conversion efficiencies of Phaseolus vulgaris L. under different soil moisture levels near Nairobi, Kenya

ＩｎｔｒｏｄｕｃｔｉｏｎＫｅｎｙａ○ｓｈｉｇｈｐｏｐｕｌａｔｉｏｎｇｒｏｗｔｈｒａｔｅｈａｓｃｒｅａｔｅｄｐｒｅｓｓｕｒｅｏｎｔｈｅｈｉｇｈｐｏｔｅｎｔｉａｌａｒｅａｓ．Ｔｈｉｓｈａｓｒｅｓｕｌｔｅｄｉｎｔｈｅｍｉｇｒａｔｉｏｎｏｆｐｅｏｐｌｅｔｏｕｎｃｕｌｔｉｖａｔｅｄ“ｍａｒｇｉｎａｌ”ｌａｎｄｓｗｈｉｃｈｍａｋｅｕｐａｂｏｕｔ８０％ｏｆｔｈｅｃｏｕｎｔｒｙａｎｄａｒｅｐｒｅｄｏｍｉｎａｎｔｌｙｏｆｌｏｗａｇｒｉｃｕｌｔｕｒａｌｐｒｏｄｕｃｔｉｖｉｔｙ（Ｈｏｒｎｅｔｚ，１９９０）．Ｔｈｅｓｅ…     

紫外线辐射对小麦和燕麦竞争性平衡的影响--小麦和燕麦生物量结构与冠层结构

在模拟１５％臭氧层减薄条件下讨论了紫外线辐射增强对大田中小麦和燕麦在单独种植与混合种植时的生物量结构和冠层结构的影响。紫外辐射使两物种的生物量减少，使节间缩短，叶片着生高度下降，但使根冠比和单株有效穗数增加。两物种在单种和混种时对紫外辐射的反应有所不同，种间竞争有时加强紫外辐射的影响，但有时则又能抵消其作用。紫外辐射使竞争性平衡向有利于小麦的方向发展，这一改变可以部分地由两物种的生物量及冠层结构对