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Fanghui Liu,Zhe Gao,Chao Yang,Ruicheng Ma 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.9
In order to improve the estimation accuracy of the state information and save the computing time for fractional-order systems containing correlated and uncorrelated process and measurement noises, this paper investigates fractional-order extended Kalman filters for continuous-time nonlinear fractional-order systems using the method of fractional-order average derivative. Compared with Grünwald-Letnikov difference, the estimation accuracy is improved via the fractional-order average derivative method. Meanwhile, the computing time in the stateestimation is saved. To deal with the correlated and uncorrelated process and measurement noises, two kinds of extended Kalman filters for nonlinear fractional-order systems are given. Finally, the effectiveness of the proposed fractional-order extended Kalman filters based on fractional-order average derivative is validated by two examples.
Jiazhong Wu,Fanghui Liu,Hui Yang,Shijing Xu,Quan Xie,Minghui Zhang,TING CHEN,Guangxin Hu,Jinben Wang 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.56 No.-
Low salinity effect has been in the center of attention as a cost-effective and environmentally friendlytechnique. Wettability alteration of the oil/brine/mica system appears to be the identified mechanism(s)to trigger the low salinity effect. While the effect of water chemistry and minerology on the wettability ofthe system has been extensively investigated, few studies have investigated the effect of specific functiongroups from crude oil on the system wettability, limiting the understanding of how specific functionalgroup contributes to the wettability. We thus experimentally measured the adhesion forces betweenmica surfaces and functional groups (e.g., C6H5–, CH3–, COOH–, and NH2–) in the presence of differentaqueous ionic solutions using chemical force microscopy (CFM). Moreover, to understand thecontribution of the structural force, the traditional Derjaguin–Landau–Verwey–Overbeek (DLVO) theorywas extended (denoted as EDLVO) tofit the force profiles using a Gauss model. Our results showed thatthe adhesion force between mica and functional groups in a decreasing order was –NH2> –COOH> –CH3> –C6H5. We also found that while DLVO forces strongly affected the tip-surface contact due to theinteractions among oil/brine/mica interfaces, the structural forces also played an important role in adistance of 1–20 nm due to the presence of H-bonds between COOH-terminated or NH2-terminated tipand mica surface. We therefore conclude that the structural force largely contributes to the adhesionforce due to the hydrophilicity or polarity of functional groups, and nucleophilic property (such as phenylgroup). Our results suggest that the polarity of the crude oil needs to be considered to screen a candidatereservoir for low salinity waterflooding projects.