排序方式: 共有76条查询结果,搜索用时 31 毫秒
61.
62.
为揭示瓦斯积聚量及瓦斯爆炸距离对风机和防爆门的影响机制,利用Fluent模拟软件,结合宁煤集团羊场湾矿的实际情况,在构建三维数学物理模型的基础上,开展不同瓦斯积聚量(56.52,113.04,169.56,226.08 m3)和不同爆炸距离(20,30,50,70 m)条件下的模拟研究。研究结果表明:风机和防爆门处超压峰值随瓦斯积聚量增加而增加,均呈线性关系,瓦斯积聚量为56.52 m3时风机处超压峰值为0.260 MPa,小于风机破坏荷载0.306 MPa;考虑安全系数前提下,当瓦斯积聚量超过56.52 m3时防爆门应开启保护风机;在确定瓦斯积聚量为56.52 m3基础上,分析不同爆炸距离对风机和防爆门影响,由模拟结果可知,风机和防爆门处超压峰值随爆炸距离增加而降低,均呈幂函数关系。研究成果可为瓦斯爆炸对风机和防爆门的影响研究提供指导。 相似文献
63.
为了研究融雪剂对道路绿化植物的影响,以大叶黄杨(Euonymus japonicus Thunb)为研究材料,研究了其在3种融雪剂(JLR-01、LBR-4、芦笛一号)不同施用量影响下的生长量和生理特性。结果表明:随着融雪剂LBR-4和芦笛一号的施用量的增大,大叶黄杨叶片的相对生长量和株高相对生长量、光合速率(Pn)、水分利用效率(WUE)、蒸腾速率(Tr)和气孔导度(Gs)随之减小,而低施用量的融雪剂JLR-01对大叶黄杨生长量、Pn、WUE和Tr有促进作用。随着融雪剂作用时间的延长,3种融雪剂的Pn和WUE也随之减小,Tr则是先减小后有所增大。当融雪剂施用量较小和胁迫时间较短时,Pn下降是因为气孔关闭;而当施用量较大和胁迫时间较长时,Pn下降是因为叶肉同化能力下降;3种融雪剂对大叶黄杨的胁迫程度由大到小的次序为:芦笛一号>LBR-4>JLR-01;大叶黄杨对3种融雪剂施用量的忍耐阈值在80 g.m-2左右,大叶黄杨对施用LBR-4和芦笛一号的耐受时间阈值大约为3周,对施用JLR-01的耐受时间阈值为3周以上。 相似文献
64.
Ping TangJuncheng Jiang Yong PanRui Wang Jiajia Jiang 《Journal of Loss Prevention in the Process Industries》2011,24(1):105-110
Life extension reliability analysis process of decommissioned transportable seamless steel gas cylinders is proposed based on reliability index and applied to a case study in this paper. The index was calculated in terms of material stress, material strength and their probabilistic distributions. Stresses were determined by membrane equations for cylindrical shell and finite element analysis for neck, shoulder and bottom. Yield strength was measured and chosen as material strength. Probabilistic distributions were determined by distribution of material hardness. Decommissioned gas cylinders, which corrode relatively more seriously than others, could be used in the analysis for conservatively determining life extension reliability. In addition, service life of gas cylinders could be extended on condition that their reliability was more than 0.99999. Finally, the proposed analysis process was applied to determine whether some decommissioned transportable seamless steel oxygen cylinders which were manufactured in 1970s could be life extended and shown to be effective. 相似文献
65.
66.
67.
Shuangde Li Jiajia Gao Yiqing He Liuxu Cao Ang Li Shengpeng Mo Yunfa Chen Yaqun Cao 《环境科学学报(英文版)》2017,29(1):157-164
Particulate matter(PM) from cooking has caused seriously indoor air pollutant and aroused risk to human health.It is urged to get deep knowledge of their spatial-temporal distribution of source emission characteristics,especially ultrafine particles(UFP 100 nm) and accumulation mode particles(AMP 100-555 nm).Four commercial cooking oils are auto dipped water to simulate cooking fume under heating to 255℃ to investigate PM emission and decay features between 0.03 and 10 μm size dimension by electrical low pressure impactor(ELPI) without ventilation.Rapeseed and sunflower produced high PM_(2.5) around5.1 mg/m~3,in comparison with those of soybean and corn(5.87 and 4.55 mg/m~3,respectively)at peak emission time between 340 and 450 sec since heating oil,but with the same level of particle numbers 6-9 × 10~5/cm~3.Mean values of PM_(1.0)/PM_(2.5) and PM_(2.5)/PM_(10) at peak emission time are around 0.51-0.55 and 0.23-0.29.After 15 min naturally deposition,decay rates of PM_(1.0),PM_(2.5) and PM_(10) are 13.3%-29.8%,20.1%-33.9%and 41.2%-54.7%,which manifest that PM_(1.0) is quite hard to decay than larger particles,PM_(2.5) and PM_(1.0).The majority of the particle emission locates at 43 nm with the largest decay rate at 75%,and shifts to a larger size between137 and 555 nm after 15 min decay.The decay rates of the particles are sensitive to the oil type. 相似文献
68.
Junfeng Xiao Yuanpeng Cheng Caixia Guo Xiangting Liu Bing Zhang Siguo Yuan Jiajia Huang 《环境科学学报(英文版)》2019,(9)
A novel functional fiber(PAN-CDs) loaded with carbon dots(CDs) with excellent photoreduction and adsorption properties for Cr(VI) was prepared via an amidization reaction between the CDs' carboxyl groups and amine groups on polyacrylonitrile(PAN)-based ion exchange fibers, which could completely preserve the fluorescence properties of the CDs. The photoluminescence(PL), photocatalysis and adsorption properties of PAN-CDs were characterized and analyzed. The PAN-CDs possess high adsorption capacity(297.6 mg/g) and excellent kinetic behavior(attaining adsorption equilibrium in 30 min)for Cr(VI) adsorption. Furthermore, the residual Cr(VI)(approximately 3 mg/L) after adsorption could be removed completely by subsequent photoreduction by the PAN-CDs.The Cr-saturated PAN-CDs could be easily separated by filtering and regenerated, with no observable decay of removal efficiency after five regeneration cycles. In addition, due to the PL quenching action of Cr(VI), the PAN-CDs can also be used as sensor for quantitative detection of trace Cr(VI) in aqueous solution. 相似文献
69.
Environmental Fluid Mechanics - This paper presents a numerical model study on the ice cover effect on bank stability in non-cohesive alluvial channels. The model consists of a coupled... 相似文献
70.
陶瓷球填料生物膜滴滤塔挂膜启动工艺及对甲苯废气的净化性能实验研究 总被引:11,自引:2,他引:11
对陶瓷球填料生物膜滴滤塔挂膜启动工艺以及挂膜后的净化性能进行了实验研究 .实验结果表明 ,挂膜过程主要由成膜期、生长期和稳定期 3个过程组成 .在挂膜期间循环液吸光度、填料床压力损失、滴滤塔降解量以及气相进出口温差的变化规律基本相同 ,这几个参数可以作为衡量挂膜完成的综合评价指标 .在挂膜初期 ,进口甲苯浓度和循环液吸光度对挂膜有很大影响 .在实验工况范围内 ,滴滤塔净化效率随着气体流量和液体流量的增大而降低 ,而进口甲苯浓度较小时 ,其对降解效率的影响较小 相似文献