Documents disponibles écrits par cet auteur

Decolorization of biopetroleum and analysis of colored components / Jinhua Li in Industrial & engineering chemistry research, Vol. 47 n°14 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4924–4928 Titre : Decolorization of biopetroleum and analysis of colored components Type de document : texte imprimé Auteurs : Jinhua Li, Auteur ; Chao Wang, Auteur ; Zhengyu Yang, Auteur Année de publication : 2008 Article en page(s) : p. 4924–4928 Langues : Anglais (eng) Mots-clés : Biopetroleum;  Decolorization;  Distillation  fractions Résumé : Biopetroleum, mainly composed of alkanes, cycloalkanes, and aromatic hydrocarbons, was prepared from biomass by direct deoxyliquefaction. The distillation fractions were obtained after distilling at different temperatures and may become dark brown in color after storage in air. To produce a visually high-grade fuel, acid-activated bentonite was selected as the adsorbent to remove the color-induced components, such as unsaturated carbonyl groups, polycyclic aromatic hydrocarbons, quinones, heterocyclic and nitrous compounds, which can be determined by using GC/MS. The raw and acid-activated bentonites were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG) and Fourier transform infrared (FTIR) spectra, respectively. The colored distillation fractions were decolorized by acid-activated bentonite. The results showed that the acid-activated bentonite was effective in removing the color-induced components from the distillation fractions, and the maximum decolorization efficiency was 86.31%. The adsorption equilibrium data were fitted to the Freundlich isotherm equation. Moreover, the product treated by the acid-activated bentonite proved to be a high-grade fuel, which is similar to −10# diesel oil (freezing point ≤ −10 °C), not only in composition but also in color. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800101j [article] Decolorization of biopetroleum and analysis of colored components [texte imprimé] / Jinhua Li, Auteur ; Chao Wang, Auteur ; Zhengyu Yang, Auteur . - 2008 . - p. 4924–4928. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4924–4928 Mots-clés : Biopetroleum;  Decolorization;  Distillation  fractions Résumé : Biopetroleum, mainly composed of alkanes, cycloalkanes, and aromatic hydrocarbons, was prepared from biomass by direct deoxyliquefaction. The distillation fractions were obtained after distilling at different temperatures and may become dark brown in color after storage in air. To produce a visually high-grade fuel, acid-activated bentonite was selected as the adsorbent to remove the color-induced components, such as unsaturated carbonyl groups, polycyclic aromatic hydrocarbons, quinones, heterocyclic and nitrous compounds, which can be determined by using GC/MS. The raw and acid-activated bentonites were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG) and Fourier transform infrared (FTIR) spectra, respectively. The colored distillation fractions were decolorized by acid-activated bentonite. The results showed that the acid-activated bentonite was effective in removing the color-induced components from the distillation fractions, and the maximum decolorization efficiency was 86.31%. The adsorption equilibrium data were fitted to the Freundlich isotherm equation. Moreover, the product treated by the acid-activated bentonite proved to be a high-grade fuel, which is similar to −10# diesel oil (freezing point ≤ −10 °C), not only in composition but also in color. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800101j

Differential transformation and its application to nonlinear optimal control / Inseok Hwang in Transactions of the ASME . Journal of dynamic systems, measurement, and control, Vol. 131 N° 5 (Septembre 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 131 N° 5 (Septembre 2009) . - 11 p. Titre : Differential transformation and its application to nonlinear optimal control Type de document : texte imprimé Auteurs : Inseok Hwang, Auteur ; Jinhua Li, Auteur ; Dzung Du, Auteur Année de publication : 2009 Article en page(s) : 11 p. Note générale : dynamic systems Langues : Anglais (eng) Mots-clés : nonlinear  optimal  control  problems;  differential  transformation Résumé : A novel numerical method based on the differential transformation is proposed for solving nonlinear optimal control problems in this paper. The differential transformation is a linear operator that transforms a function from the original time and/or space domain into another domain in order to simplify the differential calculations. The optimality conditions for the optimal control problems can be represented by algebraic and differential equations. Using the differential transformation, these algebraic and differential equations with their boundary conditions are first converted into a system of nonlinear algebraic equations. Then the numerical optimal solutions are obtained in the form of finite-term Taylor series by solving the system of nonlinear algebraic equations. The differential transformation algorithm is similar to the spectral element methods in that the computational region splits into several subregions but it uses polynomials of high degrees by keeping a small number of subregions. The differential transformation algorithm could solve the finite- (or infinite-) time horizon optimal control problems formulated as either the algebraic and ordinary differential equations using Pontryagin’s minimum principle or the Hamilton–Jacobi–Bellman partial differential equation using dynamic programming in one unified framework. In addition, the differential transformation algorithm can efficiently solve optimal control problems with the piecewise continuous dynamics and/or nonsmooth control. The performance is demonstrated through illustrative examples. DEWEY : 629.8 ISSN : 0022-0434 En ligne : http://dynamicsystems.asmedigitalcollection.asme.org/Issue.aspx?issueID=26502&di [...] [article] Differential transformation and its application to nonlinear optimal control [texte imprimé] / Inseok Hwang, Auteur ; Jinhua Li, Auteur ; Dzung Du, Auteur . - 2009 . - 11 p. dynamic systems Langues : Anglais (eng) in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 131 N° 5 (Septembre 2009) . - 11 p. Mots-clés : nonlinear  optimal  control  problems;  differential  transformation Résumé : A novel numerical method based on the differential transformation is proposed for solving nonlinear optimal control problems in this paper. The differential transformation is a linear operator that transforms a function from the original time and/or space domain into another domain in order to simplify the differential calculations. The optimality conditions for the optimal control problems can be represented by algebraic and differential equations. Using the differential transformation, these algebraic and differential equations with their boundary conditions are first converted into a system of nonlinear algebraic equations. Then the numerical optimal solutions are obtained in the form of finite-term Taylor series by solving the system of nonlinear algebraic equations. The differential transformation algorithm is similar to the spectral element methods in that the computational region splits into several subregions but it uses polynomials of high degrees by keeping a small number of subregions. The differential transformation algorithm could solve the finite- (or infinite-) time horizon optimal control problems formulated as either the algebraic and ordinary differential equations using Pontryagin’s minimum principle or the Hamilton–Jacobi–Bellman partial differential equation using dynamic programming in one unified framework. In addition, the differential transformation algorithm can efficiently solve optimal control problems with the piecewise continuous dynamics and/or nonsmooth control. The performance is demonstrated through illustrative examples. DEWEY : 629.8 ISSN : 0022-0434 En ligne : http://dynamicsystems.asmedigitalcollection.asme.org/Issue.aspx?issueID=26502&di [...]

Simulation of non - gaussian stochastic process with target power spectral density and lower - order moments / Jinhua Li in Journal of engineering mechanics, Vol. 138 N° 5 (Mai 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 5 (Mai 2012) . - pp.391-404 Titre : Simulation of non - gaussian stochastic process with target power spectral density and lower - order moments Type de document : texte imprimé Auteurs : Jinhua Li, Auteur ; Chunxiang Li, Auteur Année de publication : 2012 Article en page(s) : pp.391-404 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Simulation  Non-Gaussian  Stochastic  process  PSD  Lower-order  moments  AR  ARMA  model Résumé : In this paper, a direct simulation algorithm is presented for the generation of a class of non-Gaussian stochastic processes according to target lower-order moments and prescribed power spectral density (PSD) function. The proposed algorithm is to expand the autoregressive (AR) model and the autoregressive moving average (ARMA) model, which are available to generate Gaussian random process, to simulate directly non-Gaussian stochastic process. The coefficients of the AR or ARMA model are determined based on the prescribed PSD function. It is well known that outputting stochastic process is also non-Gaussian if inputting white noise is non-Gaussian. But the skewness and kurtosis of the outputting non-Gaussian random process are not identical to these of inputting non-Gaussian white noise. In this paper, the relationships of lower-order moments such as skewness and kurtosis between output and input are analyzed and close to linear transformations. To corroborate the feasibility and correctness of the present methodology, numerical examples involving simulation of fluctuating wind pressures are taken into consideration. Numerical results indicate that the skewness and kurtosis of generated wind pressures based on the AR or ARMA model closely match their targets. In addition, the PSD and correlation functions of simulated samples also show considerably good agreement with prescribed functions. Therefore, the proposed algorithm is effective to simulate directly the class of non-Gaussian stochastic process. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000349 [article] Simulation of non - gaussian stochastic process with target power spectral density and lower - order moments [texte imprimé] / Jinhua Li, Auteur ; Chunxiang Li, Auteur . - 2012 . - pp.391-404. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 5 (Mai 2012) . - pp.391-404 Mots-clés : Simulation  Non-Gaussian  Stochastic  process  PSD  Lower-order  moments  AR  ARMA  model Résumé : In this paper, a direct simulation algorithm is presented for the generation of a class of non-Gaussian stochastic processes according to target lower-order moments and prescribed power spectral density (PSD) function. The proposed algorithm is to expand the autoregressive (AR) model and the autoregressive moving average (ARMA) model, which are available to generate Gaussian random process, to simulate directly non-Gaussian stochastic process. The coefficients of the AR or ARMA model are determined based on the prescribed PSD function. It is well known that outputting stochastic process is also non-Gaussian if inputting white noise is non-Gaussian. But the skewness and kurtosis of the outputting non-Gaussian random process are not identical to these of inputting non-Gaussian white noise. In this paper, the relationships of lower-order moments such as skewness and kurtosis between output and input are analyzed and close to linear transformations. To corroborate the feasibility and correctness of the present methodology, numerical examples involving simulation of fluctuating wind pressures are taken into consideration. Numerical results indicate that the skewness and kurtosis of generated wind pressures based on the AR or ARMA model closely match their targets. In addition, the PSD and correlation functions of simulated samples also show considerably good agreement with prescribed functions. Therefore, the proposed algorithm is effective to simulate directly the class of non-Gaussian stochastic process. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000349