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Characterization of dual-structure pore-size distribution of soil / X. Li in Canadian geotechnical journal, Vol. 46 N° 2 (Fevrier 2009) 

Public ISBD [article]  in Canadian geotechnical journal > Vol. 46 N° 2 (Fevrier 2009) . - pp. 129–141 Titre : Characterization of dual-structure pore-size distribution of soil Type de document : texte imprimé Auteurs : X. Li, Auteur ; Zhang, L. M., Auteur Article en page(s) : pp. 129–141 Note générale : Sciences de la Terre Langues : Anglais (eng) Mots-clés : Compaction  Pore-size  distribution  Soil  fabric  Dual  porosity  Saturation  Drying  Compaction  Distribution  de  la  dimension  des  pores  Assemblage  du  sol  Porosité  double  Saturation  Séchage Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : The microporosity structure of soil provides important information in understanding the shear strength, compressibility, water-retention ability, and hydraulic conductivity of soils. It is a soil characteristic that depends on sample preparation method and wetting–drying history. A comprehensive study of the microporosity structure of a lean clay with sand was conducted in this research to investigate variations of the microporosity structure during compaction, saturation, and drying processes. Scanning electron microscopy was used to observe the microporosity structure of soil sample surfaces. Mercury intrusion porosimetry was used to measure the microporosity structure quantitatively by showing the relationship between cumulative pore volumes and pore radius. The experimental results show that a dual-porosity structure (i.e., interaggregate pores and intra-aggregate pores) forms during the compaction process. The interaggregate pores are compressible and the associated volume is closely related to the final void ratio of the compacted sample. Changes to interaggregate pores is dominant during compaction, but changes to intra-aggregate pores is dominant during saturation and drying. Based on the experimental results, a dual-porosity structure model was developed by relating the pore-size distribution to the void ratio. Consequently, the pore-size distribution at any void ratio can be predicted. La structure de la microporosité des sols révèle des informations importantes pour la compréhension de la résistance au cisaillement, de la compressibilité, de la capacité de rétention d’eau et de la conductivité hydraulique des sols. La microporosité est une caractéristique du sol qui dépend de la méthode de préparation de l’échantillon ainsi que de son historique de saturation – drainage. L’étude présentée consiste en une investigation de la variation de la structure de la microporosité d’une argile avec sable durant sa compaction, saturation et drainage. Le microscope électronique à balayage a été utilisé pour observer la microporosité à la surface des échantillons. La porosimétrie par intrusion au mercure a évalué la structure de la microporosité quantitativement en démontrant la relation entre le volume cumulatif des pores et le rayon des pores. Les résultats expérimentaux montrent qu’une structure de porosité double (pores inter-agrégats et pores intra-agrégats) est formée durant le processus de compaction. Les pores inter-agrégats sont compressibles et leur volume est étroitement associé à l’indice des vides final du sol compacté. Les modifications aux pores inter-agrégats sont prédominantes durant le processus de compaction, tandis que les modifications aux pores intra-agrégats surviennent principalement durant la saturation et le drainage. Basé sur les résultats expérimentaux, un modèle de structure de porosité double a été développé en reliant la distribution de la dimension des pores et l’indice des vides. De cette façon, la distribution de la dimension des pores peut être prédite pour n’importe quel indice des vides. DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...] [article] Characterization of dual-structure pore-size distribution of soil [texte imprimé] / X. Li, Auteur ; Zhang, L. M., Auteur . - pp. 129–141. Sciences de la Terre Langues : Anglais (eng) in Canadian geotechnical journal > Vol. 46 N° 2 (Fevrier 2009) . - pp. 129–141 Mots-clés : Compaction  Pore-size  distribution  Soil  fabric  Dual  porosity  Saturation  Drying  Compaction  Distribution  de  la  dimension  des  pores  Assemblage  du  sol  Porosité  double  Saturation  Séchage Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : The microporosity structure of soil provides important information in understanding the shear strength, compressibility, water-retention ability, and hydraulic conductivity of soils. It is a soil characteristic that depends on sample preparation method and wetting–drying history. A comprehensive study of the microporosity structure of a lean clay with sand was conducted in this research to investigate variations of the microporosity structure during compaction, saturation, and drying processes. Scanning electron microscopy was used to observe the microporosity structure of soil sample surfaces. Mercury intrusion porosimetry was used to measure the microporosity structure quantitatively by showing the relationship between cumulative pore volumes and pore radius. The experimental results show that a dual-porosity structure (i.e., interaggregate pores and intra-aggregate pores) forms during the compaction process. The interaggregate pores are compressible and the associated volume is closely related to the final void ratio of the compacted sample. Changes to interaggregate pores is dominant during compaction, but changes to intra-aggregate pores is dominant during saturation and drying. Based on the experimental results, a dual-porosity structure model was developed by relating the pore-size distribution to the void ratio. Consequently, the pore-size distribution at any void ratio can be predicted. La structure de la microporosité des sols révèle des informations importantes pour la compréhension de la résistance au cisaillement, de la compressibilité, de la capacité de rétention d’eau et de la conductivité hydraulique des sols. La microporosité est une caractéristique du sol qui dépend de la méthode de préparation de l’échantillon ainsi que de son historique de saturation – drainage. L’étude présentée consiste en une investigation de la variation de la structure de la microporosité d’une argile avec sable durant sa compaction, saturation et drainage. Le microscope électronique à balayage a été utilisé pour observer la microporosité à la surface des échantillons. La porosimétrie par intrusion au mercure a évalué la structure de la microporosité quantitativement en démontrant la relation entre le volume cumulatif des pores et le rayon des pores. Les résultats expérimentaux montrent qu’une structure de porosité double (pores inter-agrégats et pores intra-agrégats) est formée durant le processus de compaction. Les pores inter-agrégats sont compressibles et leur volume est étroitement associé à l’indice des vides final du sol compacté. Les modifications aux pores inter-agrégats sont prédominantes durant le processus de compaction, tandis que les modifications aux pores intra-agrégats surviennent principalement durant la saturation et le drainage. Basé sur les résultats expérimentaux, un modèle de structure de porosité double a été développé en reliant la distribution de la dimension des pores et l’indice des vides. De cette façon, la distribution de la dimension des pores peut être prédite pour n’importe quel indice des vides. DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...]

Micro-electrochemical characterization of galvanic corrosion of TA2/316L composite plate / X. Cheng in Materials and corrosion, Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 12 (Décembre 2011) . - pp. 1106–1110 Titre : Micro-electrochemical characterization of galvanic corrosion of TA2/316L composite plate Type de document : texte imprimé Auteurs : X. Cheng, Auteur ; X. Li, Auteur ; C. Dong, Auteur Année de publication : 2012 Article en page(s) : pp. 1106–1110 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Micro-electrochemical  measurements  Galvanic  corrosion  Stainless  steel Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Galvanic corrosion behavior of TA2/316L composite plate was investigated in the solution of 3.5 wt% NaCl by galvanic potential monitoring, scanning localized electrochemical impedance spectroscopy (LEIS) and scanning vibrating micro-electrode (SVME) techniques. The results demonstrated that the pitting corrosion resistance of 316L for the galvanic combination sample is lower, and the coupled current density is higher than for the single 316L sample. It indicates that the galvanic action works on the corrosion behavior of the TA2 titanium alloy/316L stainless steel galvanic combination in sodium chloride solution. The galvanic effect width was determined as 1500 µm. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005644/abstract [article] Micro-electrochemical characterization of galvanic corrosion of TA2/316L composite plate [texte imprimé] / X. Cheng, Auteur ; X. Li, Auteur ; C. Dong, Auteur . - 2012 . - pp. 1106–1110. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 12 (Décembre 2011) . - pp. 1106–1110 Mots-clés : Micro-electrochemical  measurements  Galvanic  corrosion  Stainless  steel Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Galvanic corrosion behavior of TA2/316L composite plate was investigated in the solution of 3.5 wt% NaCl by galvanic potential monitoring, scanning localized electrochemical impedance spectroscopy (LEIS) and scanning vibrating micro-electrode (SVME) techniques. The results demonstrated that the pitting corrosion resistance of 316L for the galvanic combination sample is lower, and the coupled current density is higher than for the single 316L sample. It indicates that the galvanic action works on the corrosion behavior of the TA2 titanium alloy/316L stainless steel galvanic combination in sodium chloride solution. The galvanic effect width was determined as 1500 µm. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005644/abstract

Microporosity structure of coarse granular soils / Zhang, L. M. in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 10 (Octobre 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 10 (Octobre 2010) . - pp. 1425-1436 Titre : Microporosity structure of coarse granular soils Type de document : texte imprimé Auteurs : Zhang, L. M., Auteur ; X. Li, Auteur Année de publication : 2010 Article en page(s) : pp. 1425-1436 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Coarse-grained  soils  Hydraulic  conductivity  Microstructures  Microporosity  Porosity  Soil  compaction  Unsaturated  soils Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : To date the microporosity structures of coarse soils with various coarse/fines contents are still not fully understood. In this study, the pore-size distributions (PSDs) of five types of soil varying from gravel to clay were characterized using mercury intrusion porosimetry. The soil with a coarse content below 70% (i.e., fines content above 30%) is found to have a fines-controlled microstructure, which is sensitive to water content changes. Such soil forms a dual-porosity structure due to compaction, in which both intraaggregate pores and interaggregate pores are dominant. After saturation, the dual-porosity structure evolves into a unimodal porosity structure dominated by the intraaggregate pores. During drying, such soil exhibits a significant reduction of total volume. The soil with a coarse content above 70% instead has a coarse-controlled microstructure, which is stable upon water content changes. Such soil maintains dual-porosity structures no matter if the soil is compacted, saturated, or dried. As an example of application, the measured PSDs are used to predict the soil water characteristic curves (SWCCs) for the test soils and the predictions are consistent with the SWCCs measured in the laboratory. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...] [article] Microporosity structure of coarse granular soils [texte imprimé] / Zhang, L. M., Auteur ; X. Li, Auteur . - 2010 . - pp. 1425-1436. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 10 (Octobre 2010) . - pp. 1425-1436 Mots-clés : Coarse-grained  soils  Hydraulic  conductivity  Microstructures  Microporosity  Porosity  Soil  compaction  Unsaturated  soils Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : To date the microporosity structures of coarse soils with various coarse/fines contents are still not fully understood. In this study, the pore-size distributions (PSDs) of five types of soil varying from gravel to clay were characterized using mercury intrusion porosimetry. The soil with a coarse content below 70% (i.e., fines content above 30%) is found to have a fines-controlled microstructure, which is sensitive to water content changes. Such soil forms a dual-porosity structure due to compaction, in which both intraaggregate pores and interaggregate pores are dominant. After saturation, the dual-porosity structure evolves into a unimodal porosity structure dominated by the intraaggregate pores. During drying, such soil exhibits a significant reduction of total volume. The soil with a coarse content above 70% instead has a coarse-controlled microstructure, which is stable upon water content changes. Such soil maintains dual-porosity structures no matter if the soil is compacted, saturated, or dried. As an example of application, the measured PSDs are used to predict the soil water characteristic curves (SWCCs) for the test soils and the predictions are consistent with the SWCCs measured in the laboratory. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...]

Preparation and characterization of ultrathin palladium membranes / X. Li in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2061–2065 Titre : Preparation and characterization of ultrathin palladium membranes Type de document : texte imprimé Auteurs : X. Li, Auteur ; T. M. Liu, Auteur ; D. Huang, Auteur Année de publication : 2009 Article en page(s) : p. 2061–2065 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ultrathin  palladium  membrane  Photocatalytic  deposition  pretreatment  Electroless  modification  method Résumé : An ultrathin palladium membrane (1 μm) has been prepared by an improved photocatalytic deposition (PCD) pretreatment and the electroless modification method. SEM results demonstrated good adhesion of the plated palladium membrane on the porous composite TiO2 support and dense coalescence of the palladium membrane. The flux and H2/N2 selectivity of the palladium membrane were determined in the temperature range of 623−823 K and the pressure difference range of 0.02−0.15 MPa. At 673 K and 0.1 MPa pressure difference, the hydrogen permeation flux of the composite membrane was as high as 0.27 mol m−2 s−1, and the H2/N2 selectivity coefficient was 361. In this study, the activation energy of hydrogen permeation through the composite palladium membrane was 17 kJ/mol. The corrected pressure exponent for the palladium composite membrane was nearly 0.8 deviated from Sievert’s law. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8004644 [article] Preparation and characterization of ultrathin palladium membranes [texte imprimé] / X. Li, Auteur ; T. M. Liu, Auteur ; D. Huang, Auteur . - 2009 . - p. 2061–2065. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2061–2065 Mots-clés : Ultrathin  palladium  membrane  Photocatalytic  deposition  pretreatment  Electroless  modification  method Résumé : An ultrathin palladium membrane (1 μm) has been prepared by an improved photocatalytic deposition (PCD) pretreatment and the electroless modification method. SEM results demonstrated good adhesion of the plated palladium membrane on the porous composite TiO2 support and dense coalescence of the palladium membrane. The flux and H2/N2 selectivity of the palladium membrane were determined in the temperature range of 623−823 K and the pressure difference range of 0.02−0.15 MPa. At 673 K and 0.1 MPa pressure difference, the hydrogen permeation flux of the composite membrane was as high as 0.27 mol m−2 s−1, and the H2/N2 selectivity coefficient was 361. In this study, the activation energy of hydrogen permeation through the composite palladium membrane was 17 kJ/mol. The corrected pressure exponent for the palladium composite membrane was nearly 0.8 deviated from Sievert’s law. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8004644

Synthesis and characterization of magnesium hydroxide using a bvubbling setup / X. Li in Industrial & engineering chemistry research, Vol. 48 N°2 (Janvier 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 763–768 Titre : Synthesis and characterization of magnesium hydroxide using a bvubbling setup Type de document : texte imprimé Auteurs : X. Li, Auteur ; G. B. Ma, Auteur ; Y. Y. Liu, Auteur Année de publication : 2009 Article en page(s) : p. 763–768 Note générale : chemical engineering Langues : Anglais (eng) Mots-clés : Magnesium  --  Hydroxide  -Synthesis  --Characterization Résumé : Magnesium hydroxide [MH] with porous nanoplates were synthesized from boric magnesium fertilizer (MgSO4·7H2O), using a large bubbling setup designed by the authors. The regular hexagonal plates of MH with a smaller specific area were formed after hydrothermal treatment. The effects of various operating variables, including the ammonia flow rate, reaction temperature, magnesium source, particle sizes, and dispersion properties of the synthesis products were investigated. X-ray diffraction, scanning electron microscopy, laser particle size analyzer, and thermogravimetric analyzer have been employed to characterize these products. The results showed that the mean particle size (D50) of the MH was about 2 μm, and products were loose enough for filtering. The diffraction intensity of the (001) direction was higher than the (101) direction. The Mg2+ conversion in the continuous setup reached 95% and the decomposition temperature of products was 370 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801306f [article] Synthesis and characterization of magnesium hydroxide using a bvubbling setup [texte imprimé] / X. Li, Auteur ; G. B. Ma, Auteur ; Y. Y. Liu, Auteur . - 2009 . - p. 763–768. chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 763–768 Mots-clés : Magnesium  --  Hydroxide  -Synthesis  --Characterization Résumé : Magnesium hydroxide [MH] with porous nanoplates were synthesized from boric magnesium fertilizer (MgSO4·7H2O), using a large bubbling setup designed by the authors. The regular hexagonal plates of MH with a smaller specific area were formed after hydrothermal treatment. The effects of various operating variables, including the ammonia flow rate, reaction temperature, magnesium source, particle sizes, and dispersion properties of the synthesis products were investigated. X-ray diffraction, scanning electron microscopy, laser particle size analyzer, and thermogravimetric analyzer have been employed to characterize these products. The results showed that the mean particle size (D50) of the MH was about 2 μm, and products were loose enough for filtering. The diffraction intensity of the (001) direction was higher than the (101) direction. The Mg2+ conversion in the continuous setup reached 95% and the decomposition temperature of products was 370 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801306f

Wetting front advancing column test for measuring unsaturated hydraulic conductivity / X. Li in Canadian geotechnical journal, Vol. 46 N° 12 (Décembre 2009) 

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