Documents disponibles écrits par cet auteur

Analysis of flow and mixing characteristics of planar asymmetric split - and - recombine (P - SAR) micromixers with fan - shaped cavities / Guodong Xia in Industrial & engineering chemistry research, Vol. 51 N° 22 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp.7816–7827 Titre : Analysis of flow and mixing characteristics of planar asymmetric split - and - recombine (P - SAR) micromixers with fan - shaped cavities Type de document : texte imprimé Auteurs : Guodong Xia, Auteur ; Jian Li, Auteur ; Xinping Tian, Auteur Année de publication : 2012 Article en page(s) : pp.7816–7827 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Micromixer  Planar  asymmetric Résumé : A modified micromixer design based on the concept of multidirectional vortices and unbalanced splitting and recombining of fluid streams is described in this work. The purpose of this study was to demonstrate that the combination of unbalanced inertial collisions, multidirectional vortices, and converging/diverging flow caused by the fan-shaped cavities contributes to the improvement of the mixing effectiveness. By using computational fluid dynamics (CFD), numerous studies of the mixing performance and flow features were completed at moderately low Reynolds numbers ranging from 1 to 80. Experimental analysis of the mass transfer and mixing quality along this modified micromixer was performed to validate the numerical results. The computational and experimental results for the concentration distributions and flow patterns reveal the following trends: (i) The combination of transverse Dean vortices effect (vertical plane) and expansion vortices (horizontal plane) effectively contribute to the considerable improvement of the mixing performance. The experimental results were consistent with the numerical results in this respect. (ii) The geometric parameters and the arrangement of the fan-shaped cavity structure are two important factors affecting the mixing performance. When the fan-shaped cavity channel is 3 times as wide as the major subchannel, the mixing index of this type of micromixer was found to reach around 75% at Reynolds numbers larger than 60. Furthermore, we also analyzed the relation between mixing efficiency and pressure drop simultaneously. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2026234 [article] Analysis of flow and mixing characteristics of planar asymmetric split - and - recombine (P - SAR) micromixers with fan - shaped cavities [texte imprimé] / Guodong Xia, Auteur ; Jian Li, Auteur ; Xinping Tian, Auteur . - 2012 . - pp.7816–7827. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp.7816–7827 Mots-clés : Micromixer  Planar  asymmetric Résumé : A modified micromixer design based on the concept of multidirectional vortices and unbalanced splitting and recombining of fluid streams is described in this work. The purpose of this study was to demonstrate that the combination of unbalanced inertial collisions, multidirectional vortices, and converging/diverging flow caused by the fan-shaped cavities contributes to the improvement of the mixing effectiveness. By using computational fluid dynamics (CFD), numerous studies of the mixing performance and flow features were completed at moderately low Reynolds numbers ranging from 1 to 80. Experimental analysis of the mass transfer and mixing quality along this modified micromixer was performed to validate the numerical results. The computational and experimental results for the concentration distributions and flow patterns reveal the following trends: (i) The combination of transverse Dean vortices effect (vertical plane) and expansion vortices (horizontal plane) effectively contribute to the considerable improvement of the mixing performance. The experimental results were consistent with the numerical results in this respect. (ii) The geometric parameters and the arrangement of the fan-shaped cavity structure are two important factors affecting the mixing performance. When the fan-shaped cavity channel is 3 times as wide as the major subchannel, the mixing index of this type of micromixer was found to reach around 75% at Reynolds numbers larger than 60. Furthermore, we also analyzed the relation between mixing efficiency and pressure drop simultaneously. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2026234

Linear predictor-based lossless compression of vibration sensor data / Yunfeng Zhang in Journal of engineering mechanics, Vol. 133 N°4 (Avril 2007) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 133 N°4 (Avril 2007) . - pp.431–441. Titre : Linear predictor-based lossless compression of vibration sensor data : systems approach Type de document : texte imprimé Auteurs : Yunfeng Zhang, Auteur ; Jian Li, Auteur Année de publication : 2007 Article en page(s) : pp.431–441. Note générale : Applied mechanics Langues : Anglais (eng) Mots-clés : Data  processing  Information  management  Monitoring  Sensors  Signal  processing  Vibration Résumé : This paper presents a novel systems approach to compressing sensor network data. Unlike previous data compression methods, the proposed lossless linear predictor-based sensor data compression method utilizes structural system information to minimize the signal correlation in sensor network data. In the proposed method, linear predictor is derived in a system identification framework in which auto-regressive (AR) model is used as its model structure and the instrumental variables (IV) method is used to calculate the predictor parameters. A parametric study was carried out to study the effects of changes in system property, number of sensors, and sensor noise level on the compression performance of the proposed method. Both numerical simulation and experimental results show that the proposed sensor data compression method has a better compression performance than conventional linear predictor-based data compression method for single sensor. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A4%2843 [...] [article] Linear predictor-based lossless compression of vibration sensor data : systems approach [texte imprimé] / Yunfeng Zhang, Auteur ; Jian Li, Auteur . - 2007 . - pp.431–441. Applied mechanics Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 133 N°4 (Avril 2007) . - pp.431–441. Mots-clés : Data  processing  Information  management  Monitoring  Sensors  Signal  processing  Vibration Résumé : This paper presents a novel systems approach to compressing sensor network data. Unlike previous data compression methods, the proposed lossless linear predictor-based sensor data compression method utilizes structural system information to minimize the signal correlation in sensor network data. In the proposed method, linear predictor is derived in a system identification framework in which auto-regressive (AR) model is used as its model structure and the instrumental variables (IV) method is used to calculate the predictor parameters. A parametric study was carried out to study the effects of changes in system property, number of sensors, and sensor noise level on the compression performance of the proposed method. Both numerical simulation and experimental results show that the proposed sensor data compression method has a better compression performance than conventional linear predictor-based data compression method for single sensor. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282007%29133%3A4%2843 [...]

Reactive deposition of palladium nanoparticles onto zeolite membranes in supercritical CO2 / Xiufeng Liu in Industrial & engineering chemistry research, Vol. 49 N° 18 (Septembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 18 (Septembre 2010) . - pp. 8826–8831 Titre : Reactive deposition of palladium nanoparticles onto zeolite membranes in supercritical CO2 Type de document : texte imprimé Auteurs : Xiufeng Liu, Auteur ; Wei Liu, Auteur ; Jian Li, Auteur Année de publication : 2010 Article en page(s) : pp. 8826–8831 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Nanoparticles  Zeolite  membranes Résumé : Pd/Si-MFI membranes are fabricated by depositing palladium nanoparticles onto Si-MFI membranes via opposing reactants chemical fluid deposition in supercritical carbon dioxide. Palladium hexafluoroacetylacetonate [Pd(hfac)2] and ethanol are used as the Pd precursor and the reducing agent, respectively, in the deposition process. The resulting Pd/Si-MFI membrane is characterized using SEM, XRD, EPMA, TEM, and EDX techniques. It is demonstrated that a continuous layer of Pd particles with size of 10 nm is covered on the matrix surface while 30-nm Pd particles are plugged into the defects within the matrix. The H2/N2 permselectivity has been significantly increased due to the deposition of Pd nanoparticles in the Si-MFI membrane, which could keep stable below the critical temperature. This bifunctional membrane and similar membranes possess the application potential to achieve various one-step syntheses. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100655m [article] Reactive deposition of palladium nanoparticles onto zeolite membranes in supercritical CO2 [texte imprimé] / Xiufeng Liu, Auteur ; Wei Liu, Auteur ; Jian Li, Auteur . - 2010 . - pp. 8826–8831. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 18 (Septembre 2010) . - pp. 8826–8831 Mots-clés : Nanoparticles  Zeolite  membranes Résumé : Pd/Si-MFI membranes are fabricated by depositing palladium nanoparticles onto Si-MFI membranes via opposing reactants chemical fluid deposition in supercritical carbon dioxide. Palladium hexafluoroacetylacetonate [Pd(hfac)2] and ethanol are used as the Pd precursor and the reducing agent, respectively, in the deposition process. The resulting Pd/Si-MFI membrane is characterized using SEM, XRD, EPMA, TEM, and EDX techniques. It is demonstrated that a continuous layer of Pd particles with size of 10 nm is covered on the matrix surface while 30-nm Pd particles are plugged into the defects within the matrix. The H2/N2 permselectivity has been significantly increased due to the deposition of Pd nanoparticles in the Si-MFI membrane, which could keep stable below the critical temperature. This bifunctional membrane and similar membranes possess the application potential to achieve various one-step syntheses. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100655m

Study of wear self-repair of steel 100Cr6 rubbed with lubricants modified with schiff base copper complex / Xinlei Gao in Transactions of the ASME . Journal of tribology, Vol. 132 N° 3 (Juillet 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 132 N° 3 (Juillet 2010) . - 05 p. Titre : Study of wear self-repair of steel 100Cr6 rubbed with lubricants modified with schiff base copper complex Type de document : texte imprimé Auteurs : Xinlei Gao, Auteur ; Li Wu, Auteur ; Jian Li, Auteur Année de publication : 2011 Article en page(s) : 05 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Atomic  force  microscopy  Friction  Lubrication  Monolayers  Scanning  electron  microscopy  Steel  Voltammetry  (chemical  analysis)  Wear  X-ray  chemical  analysis  X-ray  photoelectron  spectra Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Preparation of a Cu (II) chelate of bis(salicylaldehyde)ethylenediamine was carried out directly in epoxidized rape oil via a water/oil microemulsion reactor. Detailed characterization of the friction of boundary lubrication produced by epoxidized rape oil with and without the Cu (II) chelate of bis(salicylaldehyde)ethylenediamine was performed in reciprocating sliding tests with a microtribometer. In the presence of a modification of the epoxidized rape oil with 2 wt % of the Cu (II) chelate of bis(salicylaldehyde)ethylenediamine, the friction coefficient decreased by 15%. The Cu (II) chelate of bis(salicylaldehyde)ethylenediamine served as the additive in the epoxidized rape oil and self-assembled on the surface of 100Cr6 steel. The self-assembled monolayer was detected with atomic force microscopy and scanning electron microscopy, and characterized with cyclic voltammetry. It was verified by energy dispersive spectroscopy and X-ray photoelectron spectroscopy analyses that steel/steel rubbing pairs underwent a selective transfer of organic substance and copper, as a result of lubrication with the modified lubricant. It indicated that the modification of epoxidized rape oil with Cu (II) chelate of bis(salicylaldehyde)ethylenediamine led to wear self-repair on the steel surface, with selective transfer of a film of organic substance and copper metal. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Study of wear self-repair of steel 100Cr6 rubbed with lubricants modified with schiff base copper complex [texte imprimé] / Xinlei Gao, Auteur ; Li Wu, Auteur ; Jian Li, Auteur . - 2011 . - 05 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 132 N° 3 (Juillet 2010) . - 05 p. Mots-clés : Atomic  force  microscopy  Friction  Lubrication  Monolayers  Scanning  electron  microscopy  Steel  Voltammetry  (chemical  analysis)  Wear  X-ray  chemical  analysis  X-ray  photoelectron  spectra Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Preparation of a Cu (II) chelate of bis(salicylaldehyde)ethylenediamine was carried out directly in epoxidized rape oil via a water/oil microemulsion reactor. Detailed characterization of the friction of boundary lubrication produced by epoxidized rape oil with and without the Cu (II) chelate of bis(salicylaldehyde)ethylenediamine was performed in reciprocating sliding tests with a microtribometer. In the presence of a modification of the epoxidized rape oil with 2 wt % of the Cu (II) chelate of bis(salicylaldehyde)ethylenediamine, the friction coefficient decreased by 15%. The Cu (II) chelate of bis(salicylaldehyde)ethylenediamine served as the additive in the epoxidized rape oil and self-assembled on the surface of 100Cr6 steel. The self-assembled monolayer was detected with atomic force microscopy and scanning electron microscopy, and characterized with cyclic voltammetry. It was verified by energy dispersive spectroscopy and X-ray photoelectron spectroscopy analyses that steel/steel rubbing pairs underwent a selective transfer of organic substance and copper, as a result of lubrication with the modified lubricant. It indicated that the modification of epoxidized rape oil with Cu (II) chelate of bis(salicylaldehyde)ethylenediamine led to wear self-repair on the steel surface, with selective transfer of a film of organic substance and copper metal. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...]

Substructure hybrid simulation with multiple - support excitation / Jian Li in Journal of engineering mechanics, Vol. 138 N° 7 (Juillet 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 7 (Juillet 2012) . - pp.867–876. Titre : Substructure hybrid simulation with multiple - support excitation Type de document : texte imprimé Auteurs : Jian Li, Auteur ; Billie F. Spencer, Auteur ; Amr S. Elnashai, Auteur Année de publication : 2012 Article en page(s) : pp.867–876. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Hybrid  simulation  Multiple-support  excitation,  Nonlinear  Bouc-Wen  hysteretic  model  Highway  bridge Résumé : Substructure hybrid simulation of engineering structures subjected to multiple-support excitation (MSE) is investigated. In time-history analysis of MSE problems, the equations of motion are generally posed in relative coordinates (designated EOM-rel), which only require the ground acceleration as an input. However, the suitability of EOM-rel for hybrid simulation with MSE is unclear. Because estimating the tangent stiffness of the experimental substructure during testing is challenging, constant stiffness is often adopted in widely used integration schemes for hybrid simulation (e.g., the operator-splitting method); the equivalent force is not updated during experimentation. In previous studies, the equations of motion in absolute coordinates (designated EOM-abs) have been employed for hybrid simulation considering MSE. With EOM-abs, nonlinearity in the stiffness matrix is naturally considered in the measured restoring force—no approximation is involved. One drawback to EOM-abs is that the displacement and velocity of the ground motion must be computed prior to the experiment. This paper carefully formulates the hybrid simulation problem for structures subjected to MSE and examines the tradeoffs in the two approaches. First, the EOM-rel approximation and the EOM-abs are formulated and compared for a nonlinear single degree of freedom structure with nonlinearities modeled by a Bouc-Wen model subjected to two ground inputs. Significant error is found in the EOM-rel approximation because of the constant stiffness matrices used. Both formulations are then evaluated in hybrid simulation of a four-span highway ramp bridge. This study demonstrates that the EOM-rel approximation can provide results with good accuracy if the nonlinear components of the experimental substructure do not significantly affect the global stiffness matrix. Otherwise, the EOM-abs is recommended for hybrid simulation with MSE. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000394 [article] Substructure hybrid simulation with multiple - support excitation [texte imprimé] / Jian Li, Auteur ; Billie F. Spencer, Auteur ; Amr S. Elnashai, Auteur . - 2012 . - pp.867–876. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 7 (Juillet 2012) . - pp.867–876. Mots-clés : Hybrid  simulation  Multiple-support  excitation,  Nonlinear  Bouc-Wen  hysteretic  model  Highway  bridge Résumé : Substructure hybrid simulation of engineering structures subjected to multiple-support excitation (MSE) is investigated. In time-history analysis of MSE problems, the equations of motion are generally posed in relative coordinates (designated EOM-rel), which only require the ground acceleration as an input. However, the suitability of EOM-rel for hybrid simulation with MSE is unclear. Because estimating the tangent stiffness of the experimental substructure during testing is challenging, constant stiffness is often adopted in widely used integration schemes for hybrid simulation (e.g., the operator-splitting method); the equivalent force is not updated during experimentation. In previous studies, the equations of motion in absolute coordinates (designated EOM-abs) have been employed for hybrid simulation considering MSE. With EOM-abs, nonlinearity in the stiffness matrix is naturally considered in the measured restoring force—no approximation is involved. One drawback to EOM-abs is that the displacement and velocity of the ground motion must be computed prior to the experiment. This paper carefully formulates the hybrid simulation problem for structures subjected to MSE and examines the tradeoffs in the two approaches. First, the EOM-rel approximation and the EOM-abs are formulated and compared for a nonlinear single degree of freedom structure with nonlinearities modeled by a Bouc-Wen model subjected to two ground inputs. Significant error is found in the EOM-rel approximation because of the constant stiffness matrices used. Both formulations are then evaluated in hybrid simulation of a four-span highway ramp bridge. This study demonstrates that the EOM-rel approximation can provide results with good accuracy if the nonlinear components of the experimental substructure do not significantly affect the global stiffness matrix. Otherwise, the EOM-abs is recommended for hybrid simulation with MSE. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000394

Tribological properties of steel and steel lubricated with a poly-alpha-olefin containing schiff base copper complex / Xinlei Gao in Transactions of the ASME . Journal of tribology, Vol. 134 N° 3 (Juillet 2012) 

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Two-dimensional simulation of the collapse of vapor bubbles near a wall / Luo Jing in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 9 (Septembre 2008) 

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