排序方式: 共有104条查询结果,搜索用时 31 毫秒
31.
32.
地下水曝气过程中气体流型的实验研究 总被引:3,自引:0,他引:3
以自行设计安装的二维砂箱,并首次采用乙炔作为示踪气体模拟了地下水曝气(air sparging,AS).研究表明,在20~40目白色石英砂多孔介质体系中,AS总曝气压力基本不随气体流量变化,但气体影响半径和平均饱和度随流量增加而增加.在流量为0.15m3/h时, ROI为18cm,气体的平均饱和度为0.017;当流量增为0.30m3/h时,ROI增大到37cm.平均饱和度增加为0.031.另外,曝气流量越大,水位上升越高,达到稳定所需时间越长.由乙炔示踪的AS气体分布研究中发现,在0.05m3/h曝气流量下,AS气体的分布稀疏而且分散;当曝气流量为0.15m3/h时,AS气体的分布均匀,形状近似为对称抛物形,抛物线中部区域气体的密度较高,浓度梯度较小,而抛物线边缘区域中气体的密度较低,浓度梯度较大;在0.30m3/h曝气流量条件下,气体的分布非常不均匀,较易形成优先流. 相似文献
33.
34.
35.
Bioventing is conducted on one-dimensional soil columns.A numerical model is developed for simulating the mass exchange,advective and dispersive transport and biodegradation of toluene.The model parameters are estimated independently through laboratory batch experiments,or from literature.Simulations are found to provide reasonable agreement with experimental data.Experimental results show that toluene removal due to biodegradation is more important at the later stage.The total cleanup time when NAPL(non-aqueous phase liquid)phase exists was twice more than that without NAPL.Sensitivity analysis of parameters suggests that model predictions are mainly dependent on mass transfer coefficient and microbial parameters,such as the half-saturation coefficient and maximum specific substrate utilization rate. 相似文献
36.
37.
An apparatus,desinged to simulate bubbling of a sieve tray operated in froth regime,was employed. Bubble contact angles in and above the incipient weeping regimer for an air-water-plexiglas system were investigated. The influence of both liquid cross-flow and gas up-flow upon bubble contact angles was examined. A model considering the influence of liquid cross-flow was developed to predict bubble size from a sieve hole in froth operation regime.The comparison shows that the bubble sizes predicted by the present model are consistent with our experimental values and the available published experimental data. 相似文献
38.
39.
40.
目的:介绍拇指桡侧逆行筋膜皮瓣修复拇指软组织缺损的手术方法。方法:2004年4月至2007年5月,对21例患者用拇指桡侧逆行筋膜皮瓣,分别修复拇指腹、背侧及桡侧软组织缺损。皮瓣设计在拇指桡侧,以指侧正中线为轴线,其蒂部转折点在软组织缺损区近端0.5—1.Ocm处,不能超过拇指指间关节。皮瓣面积最大4.Ocm×3.Ocm,最小2.0cm×1.5cm,吻合指神经17例。结果:21例皮瓣全部成活,术后随访6~24个月,外形美观,质地柔软,吻合指神经的指腹两点分辨觉为6~8mm,其余为8~12mm。结论:拇指桡侧逆行筋膜皮瓣具有操作简便、质地良好、血供可靠等优点,是修复拇指软组织缺损的较好方法。 相似文献