共查询到20条相似文献,搜索用时 15 毫秒
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《Atmospheric Environment. Part A. General Topics》1990,24(11):2835-2838
An infrared video camera and recording system were used to record near source plume rise from a low turbine stack at an oil gathering center at Prudhoe Bay, AK. The system provided real-time, continuous visualization of the plume using a color monitor while the images were recorded with a standard video tape recorder. Following the field study, single frame images were digitized using a micro-computer video system. As part of the digitization, the plume centerline was determined as well as an isotherm of the plume outline. In this application, one frame from each 2-min period in the record was digitized. The results were used to calculate the variability in plume centerline during each hour. During strong winds with blowing snow, the mean plume rise for the hour at 15 m downwind was 6±2 m. The observed plume rise from the turbine stack was greater than that calculated using momentum-only or buoyancy-only plume rise models and only slightly larger than that estimated from combined momentum-buoyancy plume rise models. 相似文献
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A new method of oxygen transfer efficiency (OTE) measurement for aerobic biochemical wastewater treatment system was introduced. The effluent gas and the influent air around the fan were collected and analyzed with a gas chromatograph. The ratios of the concentration of nitrogen to that of oxygen for both influent and effluent gases were determined. The reduced percentage of the ratio for the influent gases was taken as oxygen transfer efficiency (OTE). The nitrogen gas was used as an inner mark. Using this method, the OTE measurement was not affected by the temperature, water vapor mixture and carbon dioxide produced within the treatment system. The accuracy of the method was analyzed. The standard deviation of the ratios for influent and effluent gases were 0.0006 and 0.0008, respectively. The OTE values of a full-scale aeration tank were detected using this method. The OTE values of the representative spots in the aeration tank varied from 7.3% to 11.5%. 相似文献
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长光路FTIR研究OH发生体系中的OH浓度 总被引:2,自引:0,他引:2
利用长光路FTIR测定早苯、三本等芳香烃化合物在烟雾箱中光化学反应衰减,确字了NOx-H2O、Air、HONO-H2O-Air和CH3ONO-NO-Air3种体系在我灯自夸下的OH浓度,结果表明三者OH浓度范围分别为:~10^5~10^6、~10^7、~10^7~10^8molecules.cm^-3,并进一步讨论了反应前体物对生成OH浓度的影响。 相似文献
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加速器质谱法是~(129)I最灵敏的检测方法。传统方法分析样品时通常需要复杂的化学制样流程,对样品中碘元素进行分离、富集和纯化,测试周期较长,成本高。在核应急分析等类型的应用研究中,需要对大批量样品中的~(129)I含量开展快速检测,针对此类应用需求特点,本研究尝试开发一种快速、流程简便并且成本低廉的~(129)I-AMS检测方法。以三种已知~(129)I水平的国际标准物质作为研究样品,将干燥和研磨均匀化的样品粉末直接与加入过本底碘的电热导体介质(Nb粉末)混合后压入靶座,实现快速制靶,进行加速器质谱测量,再结合制靶时称量的相关质量关系数据就能直接计算得出原始样品中的~(129)I活度。通过对测量数据与已知值进行比较分析验证了方法的可靠性,估算方法的探测下限可达0.15μBq?g~(-1)。 相似文献
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《Atmospheric Environment. Part A. General Topics》1992,26(9):1735-1745
The products of the OH radical-initiated gas-phase reaction of fluorene in the presence of NOx were investigated in a 6400 ℓ all-Teflon chamber. Teh reaction products identified were fluorenone, 1-, 2-, 3- 4-nitrofluorene, three hydroxyfluorene isomers, three nitrofluorenone isomers and three hydroxynitrofluorene isomers. Of the reaction products identified, fluorenone was formed in the highest yield (9 ± 5%). The formation yields of the individual nitrofluorenes were in the order 3-nitrofluorene > 1- nitrofluorene > 4-nitrofluorene > 2-nitrofluorene, with the average 3-nitrofluorene yield being 1.4% and the total nitrofluorene yield being 2.5%. Diesel soot and ambient particulate matter showed relatively low concentrations of total nitrofluorenes when compared with the other nitro-PAH present. The measured ambient atmospheric concentrations of the nitrofluorenes were compared with levels expected on the basis of the nitrofluorene product yields from the OH radical-initiated reaction of fluorene. 相似文献
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This paper reports study of day-to-day instability in the locomotor activity rhythm of the nocturnal field mouse Mus booduga. The free-running period (τ) of this rhythm was estimated in constant darkness in n=347 adult male mice. The "onset" and "offset" of locomotor activity rhythm were used as phase markers of the circadian clock.
The precision of the onset of locomotor activity was observed to be a non-linear function of τ, with maximal precision at
τ close to 24 h. The precision of the offset of locomotor activity was found to increase with increasing τ. These results
suggest that the homeostasis of τ is tighter when τ is close to 24 h.
Received: 5 May 1998 / Accepted: 11 February 1999 相似文献
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OH自由基降解二英OCDD的反应机理及动力学研究 总被引:1,自引:0,他引:1
采用量子化学计算研究了OH自由基降解八氯代二苯并对-二英(OCDD)的微观反应机理,计算分析了微观反应进程,结果表明该反应存在两条途径:①α-氯取代:1,4,6,9位置氯取代,该路径反应活化能较高,反应难以进行,并以中间产物积聚,无法使OCDD的毒性消失;②β-氯取代:2,3,7,8位置氯取代,该路径的反应能相对较低,且能使OCDD的毒性消失,是有效降解OCDD的主要途径.结合过渡态理论,计算获得动力学参数:反应活化能为8.32 kJ·mol-1(B3LYP/6-311G++(d,g)//B3LYP/6-31G(d)),阿仑尼乌斯表达式为k=1.29×1014exp(-1049.6/T)(cm3·mole-1·s-1).这与文献实验结果取得了很好的吻合,说明本文对OH自由基降解OCDD的反应机理及动力学研究是合理且可靠的.本文的计算结果可为催化氧化降解二英的进一步研究提供理论参考. 相似文献
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大气环境中OH自由基测定 总被引:10,自引:0,他引:10
采用自旋捕集技术和电子自旋共振法结合测定大气环境中OH自由基,首先用自旋捕集剂将OH自由基捕集,生成比较稳定的自然旋加合物,,然后带回实验室处理测定,该法为开展大气光化学研究提供了一种采样方便,利于实测的方法,据3个采样点的实测结果表明,相对误差约为35%,比文献所示结果略大。 相似文献
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提出了运用熵值判别法和线性均方估计法来处理小样本数据的方法.熵值判别法是根据熵的上界对应最大的不确定度,利用所得数据的熵信息量判别数据是否含有粗大误差;线性均方估计消除粗大误差是一种采用软化的方法处理粗大误差.经过多次试验,结果表明这两种方法在处理小样本采样数据时能够有效地提高数据精度. 相似文献
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《Journal of Manufacturing Processes》2007,9(2):121-136
This paper investigates the impact of the major design parameters of an involute hob on deviations of the hob tooth profile. Desired and actual hob tooth profiles are considered. The desired hob tooth profile is given as the line of intersection of the generating surface of the involute hob by the rake face. The actual hob tooth profile is a certain linear approximation of the desired profile. To evaluate deviation of the actual hob tooth profile with respect to the desired profile, the maximal deviation of the profiles from each other is used. This deviation is measured along the pitch line of the involute hob. An analytical method for computation of the deviation is developed. Using the commercial software MathCAD/Scientific, numerous computer codes are developed. Analysis results reveal a significant impact of the major design parameters of involute hobs on hob accuracy. Optimal configuration of the hob rake face is determined in order to minimize the deviations of the actual hob tooth profile from the desired profile. Based on the research results, reliable ways are proposed for increasing the accuracy of involute hobs in actual practice. 相似文献
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为实现河流上覆水有效脱氮及快速表征氨氮的变化,采用间歇曝气研究二十埠河上覆水中氮的转化规律及去除效果,并结合三维荧光技术研究DOM(溶解性有机物)荧光强度与氨氮浓度的关系.工况运行结果表明:间歇曝气实现了上覆水的硝化反硝化脱氮,氨氮在硝化阶段呈现明显下降趋势,在反硝化阶段则呈现明显上升趋势;硝酸盐氮和亚硝酸盐氮在硝化阶段呈现明显升高而在反硝化阶段呈现明显下降趋势,而总氮呈现一直下降趋势,随着DO(溶解氧)增加,氨氮和总氮去除效果均增加,当DO分别为3.5,4.5,5.5,6.5mg/L时,上覆水中总氮分别降为5.11,1.42,1.13,0.91mg/L,氨氮分别降为4.13,1.30,0.85,0.72mg/L;荧光强度变化表明:低激发波长类酪氨酸和类色氨酸荧光强度变化与氨氮变化均呈现相同趋势,在DO分别为3.5,4.5,5.5,6.5mg/L时,低激发波长类酪氨酸和类色氨酸荧光强度之和与氨氮具有良好的相关性,其相关系数分别为0.974、0.972、0.966、0.984;研究表明,可以通过上覆水中低激发波长类酪氨酸和类色氨酸的荧光强度快速预测氨氮浓度,并根据氨氮变化及时、灵活地控制间歇曝气工艺的运行,为受污染河流提供快速有效的治理技术和科学依据. 相似文献