Numerical simulation of two-phase turbulent flow in hydraulic and hydropower engineering

In connection with the specific features of high velocity aerated flow generated by hydraulic engineering structures, the mathematical model is developed for high turbulence air-water two-phase flow with the use of twin flow theoretical model in this paper. Furthermore the numerical method is proposed to treat bubbled flows. In addition, on the basis of air-water stratified twin flow model, the new calculation methods and free surface tracking technique are proposed to describe complicated movements of the free surface. Finally, the proposed model is used to calculate artificial aerated flows. The computed results coincide quite well with experimental results. This means that the proposed method can provide solid basis for practical engineering design.     

非标准工况下空分设备增产氩的研究与实践

文章对非标准工况下的空分设备增产氩措施进行了研究。以宝钢6#60000m3/h空分设备为例,通过设计型算法和校核型算法,建立了空分设备精馏的数学模型,通过改变数学模型的参数,分析了在非标准工况下精馏塔内的组分浓度分布,并提出了优化后的操作方案和操作参数,实施后提高了空分设备的氩提取率,取得了显著的经济效益。     

跳频对GSM网络容量的贡献

本首先提出了射频跳频技术是提高网络容量的关键技术。在此基础上，以跳频为着眼点，分析并量化计算了跳频对干扰的改善度，同时根据跳频对容量的影响，给出现有技术条件下GSM网容量的极限。     

聚丙烯催化剂的研发进展

综述了用于丙烯聚合的Ziegler-Natta催化剂在给电子体技术及催化剂制备工艺等方面,茂金属催化剂在制备丙烯均聚物、丙烯共聚物及特殊聚丙烯等方面,非茂单活性中心催化剂在丙烯活性聚合、丙烯与极性单体共聚及水介质聚合等方面的研发进展;讨论了聚丙烯催化剂的前景。     

煤直接液化中SO2-4 /ZrO2固体酸的催化作用

以二苯甲烷、苯乙醚为煤的模型化合物,以四氢萘(THN)为溶剂,进行中高压加氢液化实验,结合产物的气相色谱和质谱分析,考察了SO2-4/ZrO2固体酸对煤直接液化的催化作用及加氢液化机理.实验结果表明,SO2-4/ZrO2固体酸对模型化合物的转化具有良好的催化活性,与非催化液化相比,400 ℃、H2初压5 MPa、30 min时二苯甲烷的转化率由8.96%提高到61.75%,且模型化合物的存在促进了溶剂THN的转化,上述条件下THN的转化率也达到10.92%;模型化合物及THN的转化主要包括氢解、异构、氢转移及烷基化等反应;SO2-4/ZrO2固体酸的催化作用主要为酸催化的离子反应机理,增强催化剂的酸性有利于煤的催化液化.     

助催化剂对TiCl_4/MgCl_2催化丙烯高温聚合的影响

研究了助催化剂种类(三甲基铝、三异丁基铝、三正己基铝、三乙基铝和甲基铝氧烷)及其含量对无内、外给电子体的TiCl4/MgCl2催化剂催化丙烯高温(100℃)聚合性能的影响,并用结晶分级分析、示差扫描量热和凝胶渗透色谱等方法分析了所得聚丙烯的结晶熔融行为和微观结构。实验结果表明,聚合温度从70℃升至100℃时,TiCl4/MgCl2催化剂的定向能力基本不变;100℃聚合时,以烷基化能力较弱的三异丁基铝为助催化剂时TiCl4/MgCl2催化剂的活性最高,而采用烷基化能力最强的三甲基铝为助催化剂时TiCl4/MgCl2催化剂的活性最低;100℃聚合时,助催化剂的种类对TiCl4/MgCl2催化剂的定向能力影响很小。     

离子液体用于燃料油深度脱硫的研究进展

首先介绍了加氢催化脱硫和其他脱硫技术的特点,综述了近年来国内外利用离子液体在萃取脱硫、萃取脱硫与氧化脱硫耦合、萃取脱硫与生物脱硫耦合等方面的研究。认为离子液体萃取脱硫具有操作简便、可循环使用、无需氢气、环境友好、能深度脱硫等特点,是一项具有广阔发展前景的技术。若要实现该技术的工业化应用,还需进一步加强离子液体在合成工艺、脱硫选择性及回收再生等方面的研究。     

Breakdown behavior of GaAs/AlGaAs HBTs

Avalanche breakdown behavior at the collector junction of the GaAs/AlGaAs HBT (heterojunction bipolar transistor) has been studied. Junction breakdown characteristics displaying hard breakdown, soft breakdown, and negative resistance breakdown behavior were observed and are interpreted by analysis of localized microplasma effects, uniform microplasma-free behavior, and associated current gain measurements. Light emission from the collector-base junction of the GaAs/AlGaAs HBT was observed and used to investigate breakdown uniformity. Using a simple punchthrough breakdown model, the theoretical breakdown curves at different collector doping concentrations and thicknesses were computed and found to be in agreement with maximum breakdown voltages measured from devices displaying the most uniform junction breakdown. The serious current gain degradation of GaAs/AlGaAs HBTs at low current densities was analyzed in connection with the measurement of a large collector-emitter breakdown voltage. The unexpected functional relationship between the collector-emitter breakdown voltage and collector-base breakdown voltage is explained by the absence of a hole-feedback effect for devices not exhibiting transistor action     

Detrended Fluctuation Analysis of the Human EEG during Listening to Emotional Music

A nonlinear method named detrended fluctuation analysis （DFA） was utilized to investigate the scaling behavior of the human electroencephalogram （EEG） in three emotional music conditions （fear, happiness, sadness） and a rest condition （eyes-closed）. The results showed that the EEG exhibited scaling behavior in two regions with two scaling exponents β1 and β2 which represented the complexity of higher and lower frequency activity besides α band respectively. As the emotional intensity decreased the value of β1 increased and the value of β2 decreased. The change of β1 was weakly correlated with the ＇approach-withdrawal＇ model of emotion and both of fear and sad music made certain differences compared with the eyes-closed rest condition. The study shows that music is a powerful elicitor of emotion and that using nonlinear method can potentially contribute to the investigation of emotion.     

磷铝杂原子固体酸催化剂催化合成乙酸异丙酯

以丙烯和乙酸为原料 ,自制的磷铝杂原子固体酸作催化剂催化合成了乙酸异丙酯 ,考察了反应温度、反应压力、反应空速 (LHSV)及催化剂用量对酯化反应的影响 ,同时考察了固体酸催化剂的重复使用性。确定了最佳合成条件 :反应压力 1 5MPa,反应温度 1 60℃ ,反应空速2 0h-1,催化剂用量 2 0g。在此条件下 ,酯化率可达 91 5 % ,乙酸异丙酯选择性达 99 0 % ,且催化剂的重复使用性良好。