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RISS 인기검색어
- 검색키워드
- 저자 : Wenqing Ge (검색결과 3 건)
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Chemical processing of water-soluble species and formation of secondary organic aerosol in fogs
Kim, Hwajin,Collier, Sonya,Ge, Xinlei,Xu, Jianzhong,Sun, Yele,Jiang, Wenqing,Wang, Youliang,Herckes, Pierre,Zhang, Qi Elsevier 2019 Atmospheric environment Vol.200 No.-
<P><B>Abstract</B></P> <P>A field study on fog chemistry and aqueous-phase processing of aerosol particles was conducted in Fresno, California's San Joaquin Valley (SJV) during wintertime. Fog droplets were collected while interstitial submicron aerosol was characterized in real time using a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS). The fog samples were later analyzed using HR-AMS, ion chromatography (IC), and total organic carbon analyzer (TOC). Compared to interstitial aerosol, dissolved solutes in fog waters were composed of higher fractions of ammonium, nitrate, sulfate, methanesulfonic acid, and oxygenated organic compounds, likely due to aqueous formation of secondary species as well as enhanced gas-to-particle partitioning of water-soluble gases under humid conditions. The low-volatility dissolved organic matter in fog water (F-OA) was moderately oxidized with an average oxygen-to-carbon (O/C) ratio of 0.42. The chemical composition of F-OA appeared to be overall similar to that of oxygenated organic component in interstitial aerosol (OOA) and the HR-AMS mass spectra of F-OA and OOA are highly similar (r<SUP>2</SUP> > 0.95). However, there are also significant chemical differences as F-OA appeared to contain a larger fraction of carboxylic functional groups than OOA, indicating enhanced organic acid formation through aqueous-phase reactions. In addition, F-OA was composed of substantially more nitrogen-containing compounds, with an average N/C ratio ∼4 times that of OOA. Most strikingly was that the F-OA spectra showed substantial enhancements of the C<SUB>x</SUB>H<SUB>y</SUB>N<SUB>2</SUB> <SUP>+</SUP> (x ≥ 0; y ≥ 0) ions, which were likely contributed by imidazole- and/or pyrazine-based compounds formed from the aqueous reactions of aldehydes with amino compounds. The results of this study demonstrated that aqueous reactions in atmospheric droplets can significantly modify aerosol composition and contribute to the formation of oxygenated and nitrogen-containing organic compounds in atmospheric aerosol particles. This finding is important for understanding aerosol's effects on human health, air quality, and climate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> HR-AMS study of fog processing of PM1 in San Joaquin Valley of CA during winter. </LI> <LI> Fog waters are enriched of secondary inorganic and organic aerosol species. </LI> <LI> Organic residuals in fog waters (FOM) is moderately oxidized (average O/C = 0.42). </LI> <LI> FOM has more abundant carboxylic acid and organic nitrogen compounds than OOA. </LI> <LI> This is evidence for forming imidazole- or pyrazine-based compounds in fog waters. </LI> </UL> </P>
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Bo Li,Wenqing Ge,Dechuan Liu,Cao Tan,Binbin Sun 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6
In order to improve the handling stability of a vehicle, an optimization method of vehicle handling stability based on D-optimal test design was proposed in this paper. The multibody dynamic model was established and verified by experiments. On this basis, a response surface model was established based on D-optimal test design. An improved genetic-particle swarm algorithm was used to optimize the vehicle handling stability. The general evaluation score of vehicle handling stability was taken as the optimization objective. The vehicle structural parameters, tire and spring characteristics were regarded as design variables. The results showed that the multi-body dynamic model was accurate. After optimization, the general evaluation score of vehicle handling stability increased by 8.98 %; the score of the steering returnability and steady static circular test was increased by 20.43 % and 27.31 %, respectively. Then from the sensitivity of the optimization variables to the stability of the vehicle's handling, the rear wheel lateral stiffness has the greatest impact on it, with a sensitivity of 86.9 %; the wheelbase has the smallest impact on it, with a sensitivity of -3.39 %, which can be reduced in future optimization variable to improve design efficiency.
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