Documents disponibles écrits par cet auteur

An experimental study of effects of step roughness in skimming flows on stepped chutes / Gonzalez, Carlos A. in Journal of hydraulic research, Vol. 46 extra issue (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 24-35 Titre : An experimental study of effects of step roughness in skimming flows on stepped chutes Titre original : Etude expérimentale des effets de la rugosité des marches sur les écoulements d'écumage dans les évacuateurs en gradins Type de document : texte imprimé Auteurs : Gonzalez, Carlos A., Auteur ; Masayuki Takahashi, Auteur ; Chanson, Hubert, Auteur Article en page(s) : p. 24-35 Note générale : Hydraulique Résumé en Français Langues : Anglais (eng) Mots-clés : Stepped  chute  Skimming  flow  Step  roughness  Air-water  flow  Physical  modelling  Flow  resistance  Form  drag  Energy  dissipation  Gabion  stepped  spillway Index. décimale : 627 Ingénierie des cours d'eau naturels, des ports, des rades et des cotes. Installations de navigation, de dragage, de récupération et de sauvetage. Barrages et centrales électriques hydrauliques Résumé : On a spillway chute, a stepped design increases the rate of energy dissipation on the chute itself and reduces the size of a downstream energy dissipater. Up to date, the effects of step roughness on the flow properties remain unknown despite the practical relevance to damaged concrete steps, rock chutes and gabions weirs. New measurements were conducted in a large-size laboratory facility with two step conditions (smooth and rough) and three types of step roughness. Detailed air-water flow properties were measured systematically for several flow rates. The results showed faster flow motion on rough step chutes. Although the finding is counter-intuitive, it is linked with the location of the inception point of free-surface aeration being located further downstream than for a smooth stepped chute for an identical flow rate. In the aerated flow region, the velocities on rough-step chutes were larger than those of smooth chute flows for a given flow rate and dimensionless location from the inception point of free-surface aeration both at step edges and between step edges. The results suggest that design guidelines for smooth (concrete) stepped spillway may not be suitable to rough stepped chutes including gabion stepped weirs, and older stepped chutes with damaged steps. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com/ [article] An experimental study of effects of step roughness in skimming flows on stepped chutes = Etude expérimentale des effets de la rugosité des marches sur les écoulements d'écumage dans les évacuateurs en gradins [texte imprimé] / Gonzalez, Carlos A., Auteur ; Masayuki Takahashi, Auteur ; Chanson, Hubert, Auteur . - p. 24-35. Hydraulique Résumé en Français Langues : Anglais (eng) in Journal of hydraulic research > Vol. 46 extra issue (2008) . - p. 24-35 Mots-clés : Stepped  chute  Skimming  flow  Step  roughness  Air-water  flow  Physical  modelling  Flow  resistance  Form  drag  Energy  dissipation  Gabion  stepped  spillway Index. décimale : 627 Ingénierie des cours d'eau naturels, des ports, des rades et des cotes. Installations de navigation, de dragage, de récupération et de sauvetage. Barrages et centrales électriques hydrauliques Résumé : On a spillway chute, a stepped design increases the rate of energy dissipation on the chute itself and reduces the size of a downstream energy dissipater. Up to date, the effects of step roughness on the flow properties remain unknown despite the practical relevance to damaged concrete steps, rock chutes and gabions weirs. New measurements were conducted in a large-size laboratory facility with two step conditions (smooth and rough) and three types of step roughness. Detailed air-water flow properties were measured systematically for several flow rates. The results showed faster flow motion on rough step chutes. Although the finding is counter-intuitive, it is linked with the location of the inception point of free-surface aeration being located further downstream than for a smooth stepped chute for an identical flow rate. In the aerated flow region, the velocities on rough-step chutes were larger than those of smooth chute flows for a given flow rate and dimensionless location from the inception point of free-surface aeration both at step edges and between step edges. The results suggest that design guidelines for smooth (concrete) stepped spillway may not be suitable to rough stepped chutes including gabion stepped weirs, and older stepped chutes with damaged steps. DEWEY : 627 ISSN : 0022-1686 En ligne : http://www.journalhydraulicresearch.com/

Catalytic hydrodechlorination of tetrachloroethylene over Pd/TiO2 minimonoliths / Gonzalez, Carlos A. in Industrial & engineering chemistry research, Vol. 49 N° 2 (Janvier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 2 (Janvier 2010) . - pp 490–497 Titre : Catalytic hydrodechlorination of tetrachloroethylene over Pd/TiO2 minimonoliths Type de document : texte imprimé Auteurs : Gonzalez, Carlos A., Auteur ; Montes de Correa, Consuelo, Auteur Année de publication : 2010 Article en page(s) : pp 490–497 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalyst  Hydrodechlorination  Tétrachloroéthylène. Résumé : The gas phase catalytic hydrodechlorination (CHD) of tetrachloroethylene (TTCE) over 0.8% Pd/TiO2 (Hombikat uv-100) washcoated cordierite minimonoliths has been studied in the temperature range 120−180 °C. Experiments were carried out operating under differential regimes at a gas hourly space velocity (GHSV) of 0.45 (g min)/mL and using different concentrations of TTCE (300−1000 ppmv), hydrogen (0−10000 ppmv), ethane (0−850 ppmv), and hydrogen chloride (0−550 ppmv). The turnover frequency, specific rate constant, reaction order, and activation energy were determined. The pseudo-first-order Langmuir−Hinshelwood models adequately represent experimental results. The best adjustment corresponds to models featuring TTCE adsorption (associative or dissociative) as the limiting step. The CHD reaction is favored as TTCE and hydrogen concentrations are increased, while HCl negatively affects kinetic parameters. In order to study the causes of deactivation, fresh and used catalyst samples were characterized by nitrogen adsorption (BET), H2 chemisorption, thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and temperature-programmed oxidation coupled to mass spectrometry. Characterization results indicate that carbonaceous deposits were insignificant under reaction conditions, while the presence of HCl was the main cause of catalyst deactivation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901027y [article] Catalytic hydrodechlorination of tetrachloroethylene over Pd/TiO2 minimonoliths [texte imprimé] / Gonzalez, Carlos A., Auteur ; Montes de Correa, Consuelo, Auteur . - 2010 . - pp 490–497. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 2 (Janvier 2010) . - pp 490–497 Mots-clés : Catalyst  Hydrodechlorination  Tétrachloroéthylène. Résumé : The gas phase catalytic hydrodechlorination (CHD) of tetrachloroethylene (TTCE) over 0.8% Pd/TiO2 (Hombikat uv-100) washcoated cordierite minimonoliths has been studied in the temperature range 120−180 °C. Experiments were carried out operating under differential regimes at a gas hourly space velocity (GHSV) of 0.45 (g min)/mL and using different concentrations of TTCE (300−1000 ppmv), hydrogen (0−10000 ppmv), ethane (0−850 ppmv), and hydrogen chloride (0−550 ppmv). The turnover frequency, specific rate constant, reaction order, and activation energy were determined. The pseudo-first-order Langmuir−Hinshelwood models adequately represent experimental results. The best adjustment corresponds to models featuring TTCE adsorption (associative or dissociative) as the limiting step. The CHD reaction is favored as TTCE and hydrogen concentrations are increased, while HCl negatively affects kinetic parameters. In order to study the causes of deactivation, fresh and used catalyst samples were characterized by nitrogen adsorption (BET), H2 chemisorption, thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and temperature-programmed oxidation coupled to mass spectrometry. Characterization results indicate that carbonaceous deposits were insignificant under reaction conditions, while the presence of HCl was the main cause of catalyst deactivation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901027y