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Regularized estimation in GINAR(p) process
Haixiang Zhang,Dehui Wang,Liuquan Sun 한국통계학회 2017 Journal of the Korean Statistical Society Vol.46 No.4
This article is concerned with the regularized estimation methodology for generalized pthorder integer-valued autoregressive (GINAR(p)) process, especially when the regression coefficients are sparse. Under some mild regularity conditions, we show that the regularized estimators perform as well as if the correct submodel was known. The oracle properties of the estimators are established. Extensive Monte Carlo simulation studies demonstrate that the proposed procedure works well. To illustrate its usefulness, an application to a real data about epileptic patient is also provided.
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Guojie Zhang,Jiangwen Qu,Yannian Du,Fengbo Guo,Haixiang Zhao,Yongfa Zhang,Ying Xu 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5
H2O2 was used under different temperatures and pressures to activate three kinds of different semicokes. FTIR, BET, SEM and Boehm titration were used to analyze properties of the semi-cokes surfaces, finding that catalytic activities of these semi-cokes after modification by high temperature and high pressure H2O2 were improved. FTIR shows that the characteristic infrared absorption peak of functional groups on the semi-cokes surface does not change, but the absorption peak intensity of some functional groups is increased. The strength of –OH absorption peak of Hongce lignite (HCL) semi-coke at 3444 cm-1, carboxyl C55O at 1598 cm-1, aliphatic ether, cyclic ether and other organic functional groups at 1023 cm 1 in the modified Shenmu bituminous(SMB) semi-coke and Jincheng anthracite (JCA) semicoke are increased significantly. BET finds that the specific surface area and pore volume of three semicokes are increased after modification. Boehm titration shows that the basic functional group content in semi-coke is increased after modification, and the net alkali content is increased significantly. Compared with the raw semi-coke, SEM shows that the surface of semi-coke modified with H2O2 becomes rough. Modified JCA semi-coke surface pitted with holes, modified HCL and SMB semi-coke surface present porous.
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Cong Li,Dehui Wang,Haixiang Zhang 한국통계학회 2015 Journal of the Korean Statistical Society Vol.44 No.2
To model zero-inflated time series of counts, we propose a first-order mixed integer-valued autoregressive process with zero-inflated generalized power series innovations. These innovations contain the commonly used zero-inflated Poisson and geometric distributions. Strict stationarity, ergodicity of the process, and some important probabilistic properties such as the transition probabilities, the k-step ahead conditional mean and variance are obtained. The conditional maximum likelihood estimators for the parameters in this process are derived and the performances of the estimators are studied via simulation. As illustration, an application to an offence data set is given to show the effectiveness of the proposed model.
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Bivariate zero truncated Poisson INAR(1) process
Yan Liu,Dehui Wang,Haixiang Zhang,Ningzhong Shi 한국통계학회 2016 Journal of the Korean Statistical Society Vol.45 No.2
In this paper, we propose a new stationary bivariate first order integer-valued autoregressive (BINAR(1)) process with zero truncated Poisson marginal distribution. Some properties about this process are considered, such as probability generating function, autocorrelations, expectations and covariance matrix under conditional and unconditional situation. We also establish the strict stationarity and ergodicity of the process. Estimators of unknown parameters are derived by using Yule–Walker, conditional least squares and maximum likelihood methods. The performance of the proposed estimation procedures are evaluated through Monte Carlo simulations. An application to a real data example is also provided.
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Li, Peng,Chen, Kuo,Zhao, Lili,Zhang, Hongyu,Sun, Haixiang,Yang, Xiujie,Kim, Nam Hoon,Lee, Joong Hee,Niu, Q. Jason Elsevier Science Ltd 2019 Composites Part B, Engineering Vol.166 No.-
<P><B>Abstract</B></P> <P>Hydrogen barrier properties are characteristic of polymeric materials prepared with graphene; thus, they can be considered as a good substitute for the metal body of the traditional hydrogen storage tank. Graphene oxide/polymer layer-by-layer self-assembling film based on noncovalent force shows good hydrogen gas barrier properties. However, the dense film structure can be broken when the film is placed in water environment, especially acidic or alkaline environment, which induces to the leak of the hydrogen gas. Herein, a modified graphene oxide/polyethyleneimine reactive layer-by-layer self-assembled film for the hydrogen barrier was fabricated by the covalent bond self-assembled technology. Graphene oxide was modified with ethylene glycol diglycidyl ether to introduce epoxy groups that can react with polyethyleneimine to form covalent bonds. The modification time, modification pH value, and the feed ratio of graphene oxide/ethylene glycol diglycidyl ether were investigated in detail. Results indicate that the self-assembled films were prepared by covalent bonds between polyethyleneimine and modified graphene oxide. When the modification time was 6 h, pH value was 2, and the feed ratio of graphene oxide/ethylene glycol diglycidyl ether was 0.05/0.23, the hydrogen transmission rate of 10-bilayer modified graphene oxide/polyethyleneimine self-assembled films was 289 cm<SUP>3</SUP>/m<SUP>2</SUP>·24 h·0.1 MPa, which was decreased by 78.8% compared to that of the polyethylene terephthalate substrate films (1365 cm<SUP>3</SUP>/m<SUP>2</SUP>·24 h·0.1 MPa). Furthermore, the modified graphene oxide/polyethyleneimine reactive layer-by-layer self-assembled films exhibit acid-resistance, alkali-resistance, salt-resistance and thermal-resistance properties.</P>
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Reducing higher alcohols by nitrogen compensation during fermentation of Chinese rice wine
Xianfeng Zhong,Ali Wang,Yubo Zhang,Ziying Wu,Bin Li,Hua Lou,Guidong Huang,Haixiang Wen 한국식품과학회 2020 Food Science and Biotechnology Vol.29 No.6
Excessive amount of higher alcohols in alcoholicbeverages causes unwell and side-effect for consumersalthough adequate consumption offers joy and pleasure. Therefore, reducing higher alcohols in alcoholic beveragesis necessary. We used nitrogen compensation to reducehigher alcohols with Chinese rice wine as an experimentalmodel. Higher alcohols including isobutyl alcohols, isoamylalcohols, and b-phenethyl alcohols were significantlydecreased by 19.27, 23.03 and 19.43%, respectively, when200 mg/L (NH4)2HPO4, 5% (w/v) yeast, and 11% wheatKoji were added to fermentation broth. Meanwhile,important quality parameters remained unchanged includingfree amino acids, organic acids, biogenic amines, andesters. The expression of glutamate dehydrogenase 1 gene(GDH1) and glutamine synthetase gene (GLN1) was significantlyenhanced, 26.9- and 1.9-folds respectively. Theseresults suggest that ammonium compensation could effectivelydecrease higher alcohols in Chinese rice wine byactivating glutamate dehydrogenase (GDH) pathway inammonium assimilation.
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