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183 results on '"Hou, Keyong"'

25. Bipolar ionization source for ion mobility spectrometry based on vacuum ultraviolet radiation induced photoemission and photoionization

Author

Chert, Chuang, Dong, Can, Du, Yongzhai, Cheng, Shasha, Hart, Fenglei, Li, Lin, Wang, Weiguo, Hou, Keyong, and Li, Halyang

Subjects
Ultraviolet radiation -- Research, Spectrum analysis -- Methods, Spectrum analysis -- Technology application, Ionization -- Research, Photoemission -- Research, Technology application, Chemistry
Abstract

A novel bipolar ionization source based on a commercial vacuum-UV Kr lamp has been developed for ion mobility spectrometry (IMS), which can work in both negative and positive ion mode. Its reactant ions formed in negative ion mode were predominantly assigned to be [O.sub.3][sup.-][([H.sub.2]O).sub.n], which is different from that of the [sup.63]Ni source with purified air as carrier and drift gases. The formation of [O.sub.3][sup.-][([H.sub.2]O).sub.n], was due to the production of ozone caused by ultraviolet radiation, and the ozone concentration was measured to be about 1700 ppmv by iodometric titration method. Inorganic molecules such as S[O.sub.2], C[O.sub.2], and [H.sub.2]S can be easily detected in negative ion mode, and a linear dynamic range of 3 orders of magnitude and a limit of detection (S/N = 3) of 150 pptv were obtained for S[O.sub.2]. Its performance as a negative ion source was investigated by the detection of ammonium nitrate fuel oil explosive, N-nitrobis(2-hydroxyethyl)amine dinitrate, cyclo-1,3,5-trimethylene-2,4,6-trinitramine, and pentaerythritol tetranitrate (PETN) at 150 [degrees]C. The limit of detection was reached at 45 pg for PETN, which was much lower than the 190 pg using [sup.63]Ni ion mobility spectrometry under the same experimental condition. Also, its performance as an ordinary photoionization source was investigated in detecting benzene, toluene, and m-xylene. 10.1021/ac100342y

Published
2010

26. Effects of SF6 decomposition components and concentrations on the discharge faults and insulation defects in GIS equipment

Author

Bin Tang, Hu Xiaotong, Siwei Wang, Liangqing Zhu, Junhao Chu, Hou Keyong, Wenwu Li, Anyang Cui, Yuan Zhuang, and Yunhua He

Subjects
Feature engineering, Computer science, lcsh:Medicine, System safety, Hardware_PERFORMANCEANDRELIABILITY, Fault (power engineering), 01 natural sciences, Switchgear, Article, Theoretical chemistry, 010309 optics, 0103 physical sciences, Decomposition (computer science), Atomic and molecular physics, lcsh:Science, 010302 applied physics, Multidisciplinary, Chemical reaction model, business.industry, lcsh:R, Electrical and electronic engineering, Reliability engineering, Identification (information), lcsh:Q, Materials chemistry, Electricity, business
Abstract

Gas-insulated switchgear (GIS) is widely used across multiple electric stages and different power grid levels. However, the threat from several inevitable faults in the GIS system surrounds us for the safety of electricity use. In order to improve the evaluation ability of GIS system safety, we propose an efficient strategy by using machine learning to conduct SF6 decomposed components analysis (DCA) for further diagnosing discharge fault types in GIS. Note that the empirical probability function of different faults fitted by the Arrhenius chemical reaction model has been investigated into the robust feature engineering for machine learning based GIS diagnosing model. Six machine learning algorithms were used to establish models for the severity of discharge fault and main insulation defects, where identification algorithms were trained by learning the collection dataset composing the concentration of the different gas types (SO2, SOF2, SO2F2, CF4, and CO2, etc.) in the system and their ratios. Notably, multiple discharge fault types coexisting in GIS can be effectively identified based on a probability model. This work would provide a great insight into the development of evaluation and optimization on solving discharge fault in GIS.

Published
2020

27. Analytical solutions of the ideal model for gradient liquid chromatography

Author

Hao, Weiqiang, Zhang, Xiangmin, and Hou, Keyong

Subjects
Liquid chromatography -- Usage, Differential equations, Partial -- Usage, Chemistry
Abstract

The analytical solutions of the ideal model for gradient elution that ignores the influence of the solute concentration on the retention factor (k) were studied by using the method of characteristics for solving partial differential equations. It is found for any gradient profiles and solvent strength models used that the concentration of the solute will be discontinuous where the mobile-phase composition is. On a given characteristic curve, the product of the concentration and the retention factor is kept constant at the point where the concentration is continuous. At the point where the concentration is discontinuous, the product on the left side of this point is equal to that on the right side. We also discussed the basic equations to predict the retention time in gradient elution and introduced the injection time into them. For linear solvent strength stepwise and linear gradient elution, general expressions were proposed for the prediction and they can be used as the basis to derive others for specific gradient modes such as single linear, stepwise, and ladderlike gradients. For these modes, simple expressions to account for the band compression and the concentration change during the elution were also given.

Published
2006

41. Real-time monitoring traces of SF6 in near-source ambient air by ion mobility spectrometry.

Author

Huang, Wei, Wang, Weiguo, Chen, Chuang, Li, Yang, Wang, Zhenxin, Li, Qingyun, Li, Mei, and Hou, Keyong

Subjects
ION mobility spectroscopy, SULFUR hexafluoride, CLIMATE change, DAUGHTER ions
Abstract

The leakage of sulphur hexafluoride (SF6) gas threats the global climate changes and personnel safety. Monitoring the concentration of SF6 in its application places is an industry regulation. In this study, ion mobility spectrometry (IMS) was developed for fast monitoring traces of SF6 in near-source ambient air. Due to the water is an important part of the natural air and affects most atmospheric measurements, the operating parameters of IMS monitoring SF6 were optimised for quantitative analysis of SF6 at different relative humidity (RH). It is discovered two main product ions SF6− and SOF4− by IMS at different RH. The calibration curves of SF6 were investigated by its relationship with the peak intensity of SOF4– for real application. The time resolution of the measurement was obtained less than 1 s and the limit of detection (LOD) achieved 0.16–0.68 ppm with a data averaging of 30 times. At last, the simulated application of monitoring SF6 leakage was tested in the fume hood of our lab. The results showed a great potential application prospect of IMS in monitoring SF6 in the ambient air of its application places. [ABSTRACT FROM AUTHOR]

Published
2019
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