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- 저자 : Chunwang Dong (검색결과 3 건)
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Prediction of black tea fermentation quality indices using NIRS and nonlinear tools
Chunwang Dong,Hongkai Zhu,Jinjin Wang,Haibo Yuan,Jiewen Zhao,Quansheng Chen 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.4
Catechin content, the ratio of tea polyphenols and free amino acids (TP/FAA), as well as the ratio of theaflavins and thearubigins (TFs/TRs) are important biochemical indicators to evaluate fermentation quality. To achieve rapid determination of such biochemical indicators, synergy interval partial least square and extreme learning machine combined with an adaptive boosting algorithm, Si-ELM-AdaBoost algorithm, were used to establish quantitative analysis models between near infrared spectroscopy (NIRS) and catechin content and between TFs/TRs and TP/FAA, respectively. The results showed that prediction performance of the Si-ELM-AdaBoost mixed algorithm is superior than that of other models. The prediction results with root-mean-square error of prediction ranged from 0.006 to 0.563, the ratio performance deviation values exceeded 2.5, and predictive correlation coefficient values exceeded 0.9 in the prediction model of each biochemical indicator. NIRS combined with Si-ELMAdaBoost mixed algorithm could be utilized for online monitoring of black tea fermentation. Meanwhile, the AdaBoost algorithm effectively improved the accuracy of the ELM model and could better approach the nonlinear continuous function.
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Jie Lin,Yuan-Xu Shi,Chunwang Dong,Xiaochang Wang 한국식품과학회 2019 Food Science and Biotechnology Vol.28 No.5
The perceived aroma of oolong tea is primarilyand directly affected by its infusion matrix, and the releasepersistence of headspace volatiles can better illustrate thepersistent aroma. Headspace solid phase microextractioncoupled with gas chromatography–mass spectrometry wasperformed to analyze the headspace constituents of oolongtea. The presence of the infusion matrix seemed to preventthe headspace release of certain odorants. The release ofindole, nerolidol, and a-farnesene was also remarkablyenhanced or depressed (2.70, 1.56, and 0.69-fold in teainfusion versus in dry leaves). Moreover, the amount ofvolatile species gradually decreased with increased waterratio. Eight odorants were determined to be stable andpersistent during continuous infusion, whereas six weredetermined to be less persistent (gradually decreased orstopped releasing). The volatile dilution test further confirmedthe persistent release of nerolidol.
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Optimization of impedance boundarycontrolled casing treatment on subsonic compressors
Dakun Sun,Yuqing Wang,Jia Li,Zihan Shen,ChunWang Geng,Xu Dong,Xiaoyu Wang,Xiaofeng Sun 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.5
Foam-metal casing treatment (FMCT) has the potential to enhance the stall margin while attenuating the broadband noise of compressors. An optimized structure of FMCT backed with an air gap was developed in this study with the basis of a prediction model. The eigenvalue theory with a linear perturbation assumption was employed to judge the stability of the compression system, where the casing treatment was considered as an impedance boundary condition. The effect of this kind of casing treatment on the compression system is introduced through the equivalent surface source method. The transfer element method was applied to match the relations between perturbation parameters on the surface of each section. Prediction results showed that the double-layer configuration has better stall margin improving ability, with experimental results on the steady characteristics confirming a 39.5 % stall margin improvement. The mechanism of exerting damping on the system and thus suppressing stall precursors was proved.
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