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341.
本文基于导出的河流水质系统随机状态空间模型,提出了以能够即时测定的DO浓度实时估计不易测定的BOD浓度的塔穆勒滤波方法。通过仿真实例,证明了该滤波方法能在较大范围内适用于河流水质系统的状态估计,用DO估计BOD是可行的。 相似文献
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Jinhe Wang Shuyu Sun Chongxu Zhang Chaoyang Xue Pengfei Liu Chenglong Zhang Yujing Mu Hai Wu Defa Wang Hui Chen Jianmin Chen 《环境科学学报(英文版)》2020,32(9):256-265
Atmospheric carbonyls were measured at a typical rural area of the North China Plain (NCP) from November 13 to December 24, 2017 to investigate the pollution characteristics, sources and environmental implications. Fifteen carbonyls were detected, and formaldehyde, acetaldehyde and acetone accounted for about 81% at most. The concentration of the total carbonyls in heavily polluted days was twice more than that in clean days. In contrast to other carbonyls, m-tolualdehyde exhibited relatively high concentrations in the clean days in comparison with the polluted days. The ratios of three principal carbonyls to CO showed similar daily variations at different pollution levels with significant daytime peaks. Multiple linear regression analysis revealed that the contributions of background, primary and secondary sources to three principal carbonyls showed similar variation trends from the clean level to the heavily polluted level. The OH formation rate of formaldehyde showed a similar variation trend to its photodegradation rate, reaching the peak value at noon, which is important to maintain relatively high OH levels to initiate the oxidation of various gas-phase pollutants for secondary pollutant formation at the rural site. OH radical consumption rate and ozone formation potential (OFP) calculations showed that formaldehyde and acetaldehyde were the dominant oxidative species among measured carbonyls. As for OH radical consumption, n-butyraldehyde and m-tolualdehyde were important contributors, while for ozone formation potential, n-butyraldehyde and propionaldehyde made significant contributions. In addition, the contribution of carbonyl compounds to secondary organic aerosol (SOA) formation was also important and needs further investigation. 相似文献
343.
Effect of pyrene on denitrification activity and abundance and composition of denitrifying community in an agricultural soil 总被引:4,自引:0,他引:4
Guo GX Deng H Qiao M Mu YJ Zhu YG 《Environmental pollution (Barking, Essex : 1987)》2011,159(7):1886-1895
Toxicity of pyrene on the denitrifiers was studied by spiking an agricultural soil with pyrene to a series of concentrations (0-500 mg kg−1) followed by dose-response and dynamic incubation experiments. Results showed a positive correlation between potential denitrification activity and copy numbers of denitrifying functional genes (nirK, nirS and nosZ), and were both negatively correlated with pyrene concentrations. Based on the comparison of EC50 values, denitrifiers harboring nirK, nirS or nosZ gene were more sensitive than denitrification activity, and denitrifiers harboring nirS gene were more sensitive than that harboring nirK or nosZ genes. Seven days after spiking with EC50 concentration of pyrene, denitrifiers diversity decreased and community composition changed in comparison with the control. Phylogenetic analyses of three genes showed that the addition of pyrene increased the proportion of Bradyrhizobiaceae, Rhodospirillales, Burkholderiales and Pseudomonadales. Some species belonging to these groups were reported to be able to degrade PAHs. 相似文献
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Wang Li Liu Aiping Zhao Yuan Mu Xi Huang Tao Gao Hong Ma Jianmin 《Environmental science and pollution research international》2018,25(17):16754-16766
Environmental Science and Pollution Research - We investigated in this paper the presence of PAHs in human milk from lactating women residing in Lanzhou, a petrochemical industrialized valley city... 相似文献
347.
J. Telmo Miranda E. Muñoz Camacho J.A. Fraguela Formoso J. de D. Rodríguez García 《Journal of Loss Prevention in the Process Industries》2013,26(4):696-704
European Standard EN 14491 (2006): “Dust explosion venting protective systems”, based on German Standard VDI 3673 (2002): “Pressure venting of dust explosions”, Verein Deustcher Ingenieure, specifies the basic design requirements for the selection of dust explosion venting protection systems.In this study an investigation into the efficiency of venting surfaces in accordance with Standard EN 14491 has been undertaken to check the validation of the same. Thus, the application of the standard to an actual case of an explosion in a milk spray dryer has been studied, taking into consideration the explosive characteristics of products treated in this type of installation and their venting requirements.The results obtained indicate that, in specific situations – such as the effects of turbulence, particularly in the cone, or dust layer self-ignition – the European Standard could underestimate the venting surface requirements needed to alleviate possible excess internal pressure in order to avoid injury or structural damage to spray dryers. 相似文献
348.
J. Telmo Miranda E. Muñoz Camacho J.A. Fraguela Formoso J. de D. Rodríguez García 《Journal of Loss Prevention in the Process Industries》2013,26(4):839-850
This study presents two methodologies which can be used to determine the classification and extended area of hazardous zones caused by gas, vapours and mists. The first is based on UNE 60079/10/1: Electrical apparatus for explosive gas atmospheres – Part 10: Classification of hazardous areas, whilst the second is developed on the basis of Computational Fluid Dynamics (CFD) using the FLUENT software application. Both methodologies were applied in the same case study of differing leakage components from a dairy farm steam boiler room fuelled by liquid natural gas (LNG).The results obtained show that CFD methodology is a powerful tool with a significant capacity for determining the size of an explosive atmosphere for a broad range of exhaust sources. This methodology offers more conservative results than those obtained from the analytical methodology recommended in Standard UNE 60079/10/1. Results obtained using CFD are more useful in enabling the study of turbulence phenomena, boundaries, and diverse initial and contour conditions.In contrast, the Standard UNE 60079/10/1 methodology is less conservative and aims at determining the hypothetical volume Vz of the explosive atmosphere. This volume is a measurement of the ventilation efficiency which is in turn proportional to a massive gas release through an exhaust source divided by the number of air changes in the enclosed area.From the results obtained, it can be confirmed that Standard UNE 60079/10/1 should be revised. 相似文献
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