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861.
Shyan-Lung Chung Nan-Lung Lai 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1082-1088
This paper describes an experimental study on the suppression of soot by metal additives during the combustion of polystyrene (PS). A two-dimensional flame generated by using a Wolfhard-Parker type diffusion flame burner was used to simulate practical combustion situations. The PS was continuously fed to the burner and, by controlling the feed rate, the combustion was maintained at a steady state. The additives tested were the salts of Li, Na, K, Mg, Ca, Sr, and Ba, and the combinations of the salts of K and Ca, Sr, or Ba. These additives were added to the flame in the form of small drops of their aqueous solutions generated by an ultrasonic atomizer. Since the flow rate of the carrier gas (air) is very small, this addition causes no noticeable disturbance to the flame. The effectiveness of the alkali metals follows the order of their ease of ionization, i.e., K > Na > Li, and that of the alkaline-earth metals: Ba > Sr > Ca > Mg. At low addition rates, the effectiveness increases with increasing addition rate but becomes unaffected at high addition rates and the maximum percentage of soot suppressed is approximately 50 percent. The combinations of the two metals (i.e., K and Ca, Sr, or Ba) are much more effective than each single metal at the same addition rates and the maximum percentage of soot suppressed reaches approximately 90 percent. It is proposed that the alkaline-earth metals catalyze the ionization of the alkali metals, thus significantly enhancing the effect on soot suppression. 相似文献
862.
Alvin C.K. Lai Tracy L. Thatcher William W. Nazaroff 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1688-1699
ABSTRACT To facilitate routine health risk assessments, we develop the concept of an inhalation transfer factor (ITF). The ITF is defined as the pollutant mass inhaled by an exposed individual per unit pollutant mass emitted from an air pollution source. A cumulative population inhalation transfer factor (PITF) is also defined to describe the total fraction of an emitted pollutant inhaled by all members of the exposed population. In this paper, ITFs and PITFs are calculated for outdoor releases from area, point, and line sources, indoor releases in single zone and multizone indoor environments, and releases within motor vehicles. Typical PITFs for an urban area from emissions outdoors are ~10-6–10-3. PITFs associated with emissions in buildings or in moving vehicles are typically much higher, ~10-3–10-1. 相似文献
863.
Though polychlorinated biphenyls (PCBs) have distributed as threats in the environment to human beings for several decades, monitoring of trace level PCBs in-field is still a challenge. As a potential method for monitoring PCBs at trace levels, Raman spectroscopy has been used to detect several PCBs in the laboratory. To facilitate the development of rapid detection of PCBs by Raman spectroscopy, it is essential to investigate the Raman spectra of all PCB congeners. Herein, the stable configurations and vibrational spectra of all the PCB congeners were calculated by Gaussian 03 program package. Based on molecular symmetry, PCBs are classified into seven groups. The structural features and the normal vibration modes for each group are discussed. Taking the C(2)-2 group as an example, the wavenumber ranges of the various normal vibration modes in the Raman spectra of PCBs were analyzed. The accuracy of calculated results was verified by experimental Raman spectra of PCB77 standard. This study can elucidate further information to promote the development of Raman spectroscopy in environmental monitoring. 相似文献
864.
Arifin Siti Nor Hidayah Radin Mohamed Radin Maya Saphira Al-Gheethi Adel Lai Chin Wei Gopalakrishnan Yashni Hairuddin Nur Diyana Vo Dai-Viet 《Environmental science and pollution research international》2023,30(10):25103-25118
Environmental Science and Pollution Research - The current work aimed to investigate the degradation of the triclocarban (TCC) in aqueous solution using a modified zeolite/TiO2 composite (MZTC)... 相似文献
865.
为了解人类活动对黄河三角洲国家级自然保护区生态环境的影响,利用2000年至2019年的卫星影像数据,分析了黄河三角洲自然保护区近20年来土地利用的变化情况,并利用开发干扰指数定量分析了土地利用变化对自然保护区的影响。得出主要结论如下:黄河三角洲自然保护区近20年土地利用变化明显,草地、耕地和未利用地等土地利用面积下降,而建设用地(城乡居民点、工矿用地)和水域湿地等面积增加。变化面积占自然保护区总面积的47.0%,减少的草地和耕地等主要转为建设用地、水域湿地,主要表现为实验区内盐田和养殖塘面积的增加。2000年以来黄河三角洲自然保护区开发干扰指数逐年增大,2005年之前人类活动干扰相对轻微;2005年至2016年人类活动干扰剧烈,自然保护区开发干扰指数增加迅速,以盐田和养殖塘的开发为主要影响因素;2016年后自然保护区的监督管理力度加大,开发干扰指数趋于稳定。人类活动干扰呈现从轻微到剧烈再到稳定的过程。 相似文献
866.
在没有密度分层的容泄水体条件下,对某污水排海工程多孔喷头的射流特性进行了实验研究。文中介绍了不同排污流量和环境流速条件下,多孔喷头附近的流速场和污水场特性;并对出流平均稀释度作了分析。最后,还对该喷头周围的冲淤形态进行了探讨.文中所得的结果对实际排污系统的设计和进一步研究有一定的参考价值。 相似文献
867.
868.
Huan He Qinjin Yu Chaochao Lai Chen Zhang Muhan Liu Bin Huang Hongping Pu Xuejun Pan 《Frontiers of Environmental Science & Engineering》2021,15(2):18-30
869.
油码头生产过程中的溢油事故隐患主要集中在码头(泊位)、油品罐区、输运船舶及输油管道4个单元,文章通过查找和研究相关法律、法规、标准及规范等关于油码头溢油风险防控的要求,对不同类型的溢油事故提出了有针对性的风险防控措施,明确了油码头在溢油风险监督管理工作中应关注的重点,从而为油码头企业开展溢油风险防控措施自查提供参考。 相似文献
870.
为提升太阳能光伏并网发电向电网输送电流的质量,对新型太阳能单相光伏逆变器的应用性能展开研究。通过分析太阳能光伏发电的构成情况,创建包含太阳能光伏电池、逆变器、Boost DC/DC电路及操控电路的单相光伏并网系统,对系统核心部分的并网逆变器进行设计,选用LLCL型滤波器降低逆变器输出电流内的谐波分量并衰弱开关频率位置的高次谐波,通过加入电网电压前馈控制的方式消除电网电压对并网电流的干扰,并结合网侧电流外环PI控制对电流内环进行控制,提升整体系统稳定性。仿真实验结果表明,采用所研究逆变器的新型太阳能单相光伏并网系统具有较好的动态性能,滤波性能优越,输出并网电流稳定,说明该逆变器应用性能好。 相似文献