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991.
通过对移相控制全桥软开关功率变换器的超前臂并联谐振网络和变压器原边串联谐振网络解耦,从实现超前臂功率器件全负载范围零压软开关的角度,对超前臂谐振网络的工作过程进行了深入分析. 通过理论计算和电路仿真,研究了电源输出电流、谐振电感和电容对超前臂功率器件开关死区时间和损耗的影响规律. 考虑谐振电感的自身损耗,给出了谐振电感和电容参数的设计方法. 在此基础上,通过试验获得了超前臂功率器件的死区时间随输出电流变化的数据以及空载状态下的电压电流波形. 试验数据和波形与理论、仿真分析结果吻合良好. 相似文献
992.
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994.
Soil contamination by metals is a worldwide environmental problem. Electrokinetic extraction is a promising technology for in-situ remediation of contaminated soils of low hydraulic permeability. However, the extraction of metals is usually hindered by the high buffer capacity of natural soils. Organophosphonates are strong metal chelates as ethylenediaminetetraacetic acid(EDTA) which has been widely studied in the enhancement of electrokinetic remediation. In this study, batch desorption experiments and bench-scale electrokinetic extraction experiments were carried out to study the effect of two organophosphonates, i.e.,(nitrilotrimethylene)triphosphonate(NTMP) (ethylenedinitrilo)-tetramethylenephosphonate(EDTMP), on the extraction of cadmium from a natural clay in comparison with EDTA. Results of the batch desorption experiments showed that more than 75% of the sorbed cadmium could be dissolved into solution using 0.1 mol·L~(-1) organophosphonates or EDTA in the wide p H range of 1–11. Results of the electrokinetic extraction experiments showed that the cadmium spiked in the specimen migrated towards the anode with the enhancement of NTMP,EDTMP, and EDTA under a constant voltage gradient of approximately 1.0 V·cm-1. Although cadmium mobilization enhanced by EDTA was more efficient than that by the organophosphonates, accumulation of cadmium was observed in the vicinity of the anode. The average removal efficiencies of cadmium from the soil after approximately 5 days of electrokinetic extraction enhanced by 0.1 mol·L-1 NTMP(22.8%) and EDTMP(22.4%) were higher than that by 0.1 mol·L~(-1) EDTA(15.1%). 相似文献
995.
In this work, phenol and oxalic acid(OA) degradation in an ozone and photocatalysis integrated process was intensively conducted with Fe~(3+)/TiO_2 catalyst. The ferrioxalate complex formed between Fe~(3+) and oxalate accelerated the removal of OA in the ozonation, photolysis and photocatalytic ozonation process, for its high reactivity with ozone and UV. Phenol was degraded in ozonation and photolysis with limited TOC removal rates, but much higher TOC removal was achieved in photocatalytic ozonation due to the generation of ·OH. The sequence of UV light and ozone in the sequential process also influences the TOC removal, and ozone is very powerful to oxidize intermediates catechol and hydroquinone to maleic acid. Fenton or photo-Fenton reactions only played a small part in Fe~(3+)/TiO_2catalyzed processes, because Fe~(3+) was greatly reduced but not regenerated in many cases.The synergetic effect was found to be highly related with the property of the target pollutants. Fe~(3+)/TiO_2 catalyzed system showed the highest ability to destroy organics, but the TiO_2 catalyzed system showed little higher synergy. 相似文献
996.
含蜡原油中的蜡是原油流动性差的主要原因之一,为解决含蜡原油的流动性给原油开采和集输带来的巨大困难,需对原油进行降蜡处理。微生物降蜡利用微生物的代谢作用直接降解原油中的蜡组分,将长链烃类降解为中短链烃类,从而降低原油中的蜡含量。通过检测复配菌处理前后原油中的蜡含量及蜡晶形态,研究复配菌对原油中蜡组分的降解及原油中蜡晶形态、大小的影响,从宏观上分析复配菌的降蜡特性;通过检测降蜡处理后油样的粒径分布,从微观角度对复配菌的降蜡效果进行了验证。 相似文献
997.
以弓形折流板为基础,设定相同的工况条件,用FLUENT软件对曲面、球面和弓形三种折流板型的换热器壳程流体的流动和传热性能进行模拟,并对三种板型的管壳式换热器壳程压降及换热系数进行比较分析。通过对比三种板型换热器的传热性能及压力、温度和流速云图,分析了产生传热性能差异的原因。研究结果可为管壳式换热器折流板设计及强化传热性能提供参考,具有一定的工程实际意义。 相似文献
998.
Biodegradation of p-nitrophenol by Rhodococcus sp. CN6 with high cell surface hydrophobicity 总被引:2,自引:0,他引:2
Rhodococcus sp. CN6, isolated from a pesticide industry's effluent-sediment, was able to completely degrade and utilize 100mg/L p-nitrophenol (PNP) as the sole carbon, nitrogen and energy sources for growth in the minimal salt media (MSM) within 12h. To study the applicability of the strain for bioremediation of PNP, its degradation potential was examined in the presence of different supplemented carbon and nitrogen sources in MSM with 100mg/L PNP. Dextrin was experienced as the best supplemented carbon source used by the strain CN6 during degrading PNP. Addition of ammonium nitrate could also increase the PNP degradation rate. Preliminary studies on the surface characters of Rhodococcus sp. CN6 were undertaken for the sake of exploring its high efficiency on the degradation of PNP. Microbial adherence to hydrocarbons (MATH) assays illuminated that the strain CN6 was of higher hydrophobicity while grown on higher concentration of PNP. The results suggested that the strain CN6 could be used as a potential and efficient PNP degrader for the bioremediation of contaminated sites. 相似文献
999.
1000.
为研究泄爆口处破膜压力对管道内可燃气体燃爆特性的影响,基于大涡模拟(LES)和Zimont燃烧模型,在泄爆口不同破膜压力条件下(0.1MPa、0.3MPa、0.5MPa、0.7MPa),对预混H2/空气燃爆过程开展三维数值模拟。结果表明:在大长径比管道内,由于管壁作用、声波震荡作用及火焰的不稳定性,各工况条件下火焰传播速度曲线存在3个波峰、2个波谷;除破膜压力为0.1MPa工况外,泄爆口开启产生减速效应,使各工况条件下的火焰传播速度相比于密闭管道均下降;各工况的管内压力在泄爆口开启后整体呈下降趋势,且泄爆口的破膜压力越小,管内压力峰值越小;对比密闭管道,各工况的压力上升速率均有不同程度的降低,爆炸强度减弱,破膜压力为0.3MPa时,压力上升速率的下降幅度最大,泄爆效果最好。 相似文献