Documents disponibles écrits par cet auteur

Drive-in steel storage racks / Zhang, Hao in Journal of structural engineering, Vol. 138 N° 2 (Fevrier 2012) 

Public ISBD [article]  in Journal of structural engineering > Vol. 138 N° 2 (Fevrier 2012) . - pp. 148-156 Titre : Drive-in steel storage racks : II: Reliability-based design for forklift truck impact Type de document : texte imprimé Auteurs : Zhang, Hao, Auteur ; Benoit P. Gilbert, Auteur ; Kim J. R. Rasmussen, Auteur Année de publication : 2012 Article en page(s) : pp. 148-156 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Drive-in  racks  Impact  forces  Probability-based  design  Steel  Steel  storage  racks  Structural  reliability Résumé : Steel drive-in racks are susceptible to structural failure from accidental impact by operating forklift trucks. Under impact, the upright bends and the supported pallets may drop through the rack to cause structural collapse if the bay opening exceeds the pallet bearing width. This drop-through limit state has not been considered in existing rack design standards. This paper proposes a simple equation to calculate the equivalent static impact force based on recent tests and nonlinear dynamic analysis of drive-in steel racks. An impact load factor is developed on the basis of a structural reliability assessment, taking into account the uncertain nature of the impact force, structural resistance, and models used in structural analysis. In design practice, the bay opening is determined from factored impact loads and is not to exceed specified limits. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v138/i2/p148_s1?isAuthorized=no [article] Drive-in steel storage racks : II: Reliability-based design for forklift truck impact [texte imprimé] / Zhang, Hao, Auteur ; Benoit P. Gilbert, Auteur ; Kim J. R. Rasmussen, Auteur . - 2012 . - pp. 148-156. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 138 N° 2 (Fevrier 2012) . - pp. 148-156 Mots-clés : Drive-in  racks  Impact  forces  Probability-based  design  Steel  Steel  storage  racks  Structural  reliability Résumé : Steel drive-in racks are susceptible to structural failure from accidental impact by operating forklift trucks. Under impact, the upright bends and the supported pallets may drop through the rack to cause structural collapse if the bay opening exceeds the pallet bearing width. This drop-through limit state has not been considered in existing rack design standards. This paper proposes a simple equation to calculate the equivalent static impact force based on recent tests and nonlinear dynamic analysis of drive-in steel racks. An impact load factor is developed on the basis of a structural reliability assessment, taking into account the uncertain nature of the impact force, structural resistance, and models used in structural analysis. In design practice, the bay opening is determined from factored impact loads and is not to exceed specified limits. DEWEY : 624.17 ISSN : 0733-9445 En ligne : http://ascelibrary.org/sto/resource/1/jsendh/v138/i2/p148_s1?isAuthorized=no

Experimental investigation of thermoacoustic instabilities for a model combustor with varying fuel components / Zhang, Hao in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 3 (Mars 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 3 (Mars 2012) . - 12 p. Titre : Experimental investigation of thermoacoustic instabilities for a model combustor with varying fuel components Type de document : texte imprimé Auteurs : Zhang, Hao, Auteur ; Xiaoyu Zhang, Auteur ; Min Zhu, Auteur Année de publication : 2012 Article en page(s) : 12 p. Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Acoustic  waves  Combustion  Combustion  equipment  Flames  Fuel  Syngas  Thermal  stability Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this study, a combustion facility was constructed that includes a flexible fuel supply system to produce synthesis gas using a maximum of three components. The rig with lean premixed burner is able to operate at up to five bars. The length of the inlet plenum and the outlet boundary conditions of the combustion chamber are adjustable. Experiments were carried out under a broad range of conditions, with variations in fuel components including hydrogen, methane and carbon monoxide, equivalence ratios, thermal power and boundary conditions. The dynamic processes of self-excited combustion instabilities with variable fuel components were measured. The mechanisms of coupling between the system acoustic waves and unsteady heat release were investigated. The results show that instability modes and flame characteristics were significantly different with variations in fuel components. In addition, the results are expected to provide useful information for the design and operation of stable syngas combustion systems. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000003 [...] [article] Experimental investigation of thermoacoustic instabilities for a model combustor with varying fuel components [texte imprimé] / Zhang, Hao, Auteur ; Xiaoyu Zhang, Auteur ; Min Zhu, Auteur . - 2012 . - 12 p. Génie mécanique Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 3 (Mars 2012) . - 12 p. Mots-clés : Acoustic  waves  Combustion  Combustion  equipment  Flames  Fuel  Syngas  Thermal  stability Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In this study, a combustion facility was constructed that includes a flexible fuel supply system to produce synthesis gas using a maximum of three components. The rig with lean premixed burner is able to operate at up to five bars. The length of the inlet plenum and the outlet boundary conditions of the combustion chamber are adjustable. Experiments were carried out under a broad range of conditions, with variations in fuel components including hydrogen, methane and carbon monoxide, equivalence ratios, thermal power and boundary conditions. The dynamic processes of self-excited combustion instabilities with variable fuel components were measured. The mechanisms of coupling between the system acoustic waves and unsteady heat release were investigated. The results show that instability modes and flame characteristics were significantly different with variations in fuel components. In addition, the results are expected to provide useful information for the design and operation of stable syngas combustion systems. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000003 [...]

Optimal preorder strategy with endogenous information control / Leon Yang Chu in Management science, Vol. 57 N° 6 (Juin 2011) 

Public ISBD [article]  in Management science > Vol. 57 N° 6 (Juin 2011) . - pp. 1055-1077 Titre : Optimal preorder strategy with endogenous information control Type de document : texte imprimé Auteurs : Leon Yang Chu, Auteur ; Zhang, Hao, Auteur Année de publication : 2011 Article en page(s) : pp. 1055-1077 Note générale : Management Langues : Anglais (eng) Mots-clés : Preorder  Advance  selling  Information  release  Consumer  valuation  control Index. décimale : 658 Organisation des entreprises. Techniques du commerce Résumé : In this paper, we investigate the integrated information and pricing strategy for a seller who can take customer preorders before the release of a product. The preorder option enables the seller to sell a product at an early stage when consumers are less certain about their valuations. We find that the optimal pricing strategy may be highly dependent on the amount of information available at preorder and that a small change in the latter may cause a dramatic change in the proportion of consumers who preorder under optimal pricing. Furthermore, the seller's optimal information strategy depends on a key measure, the normalized margin, which is the ratio between the expected profit margin and the standard deviation of consumer valuation. Although the seller may want to release some information or none, she should never release all information. Finally, under the optimal information and pricing strategy, the benefit of preorder is most pronounced when the normalized margin is in a medium range. DEWEY : 658 ISSN : 0025-1909 En ligne : http://mansci.journal.informs.org/content/57/6.toc [article] Optimal preorder strategy with endogenous information control [texte imprimé] / Leon Yang Chu, Auteur ; Zhang, Hao, Auteur . - 2011 . - pp. 1055-1077. Management Langues : Anglais (eng) in Management science > Vol. 57 N° 6 (Juin 2011) . - pp. 1055-1077 Mots-clés : Preorder  Advance  selling  Information  release  Consumer  valuation  control Index. décimale : 658 Organisation des entreprises. Techniques du commerce Résumé : In this paper, we investigate the integrated information and pricing strategy for a seller who can take customer preorders before the release of a product. The preorder option enables the seller to sell a product at an early stage when consumers are less certain about their valuations. We find that the optimal pricing strategy may be highly dependent on the amount of information available at preorder and that a small change in the latter may cause a dramatic change in the proportion of consumers who preorder under optimal pricing. Furthermore, the seller's optimal information strategy depends on a key measure, the normalized margin, which is the ratio between the expected profit margin and the standard deviation of consumer valuation. Although the seller may want to release some information or none, she should never release all information. Finally, under the optimal information and pricing strategy, the benefit of preorder is most pronounced when the normalized margin is in a medium range. DEWEY : 658 ISSN : 0025-1909 En ligne : http://mansci.journal.informs.org/content/57/6.toc

Penalty-Based Solution for the Interval Finite-Element Methods / Muhanna, Rafi L. in Journal of engineering mechanics, Vol.131, N°10 (Octobre 2005)

Public ISBD [article]  in Journal of engineering mechanics > Vol.131, N°10 (Octobre 2005) . - 1102-1111 p. Titre : Penalty-Based Solution for the Interval Finite-Element Methods Titre original : Solution Pénalité-Basée pour les Méthodes d'Elément Fini d'Intervalle Type de document : texte imprimé Auteurs : Muhanna, Rafi L., Auteur ; Mullen, Robert L., Auteur ; Zhang, Hao ; Schueller, Gerhart L., Editeur scientifique Article en page(s) : 1102-1111 p. Note générale : Génie Civil, Génie Mécanique Langues : Anglais (eng) Mots-clés : Finite  element  method  Mechanical  systems  Differential  equations  Uncertainty  principles  Méthode  d'élément  fini  Systèmes  mécaniques  Equations  Principes  d'incertitude Index. décimale : 624/621.34 Résumé : A New approach for archieving guaranteed reliable results within the context of finite-element approximation of mechanical systems is developed. A Reliable analysis requires that all the sources of uncertainty and errors be accommodated. The Appropriateness of a partial differential equation to a given physical problem is beyond the scope of this work. Parameter uncertainty is treated as intervals in this work and guaranteed bounds on the "unknown" true solutions are obtained. In this paper an element-by-element penalty-based interval finite-element analysis of linear elastic structural mechanics and solid mechanics problem is introduced. Material and load uncertainties are handled simultaneously. Presented numerical examples illustrate the ability of the method to maintain very sharp solution enclosures even when the number of the interval parameters of the size of the problems is increased. Une nouvelle approche pour réaliser des résultats fiables garantis dans le contexte de l'approximation d'fini-élément des systèmes mécaniques est développée. Une analyse fiable exige que toutes les sources de l'incertitude et des erreurs soient adaptées. La convenance d'une équation partielle à un problème physique donné est au delà de la portée de ce travail. L'incertitude de paramètre est traitée pendant que des intervalles dans ce travail et les limites garanties sur les solutions vraies "inconnues" sont obtenus. En cet article un élément-par-élément pénalité-basé analyse d'fini-élément d'intervalle de mécanique structurale élastique linéaire et de problème de mécanique des solides est présenté. Des incertitudes de matériel et de charge sont manipulées simultanément. Les exemples numériques présentés illustrent la capacité de la méthode de maintenir des clôtures très pointues de solution même lorsque le nombre de paramètres d'intervalle de la taille des problèmes est augmenté. [article] Penalty-Based Solution for the Interval Finite-Element Methods = Solution Pénalité-Basée pour les Méthodes d'Elément Fini d'Intervalle [texte imprimé] / Muhanna, Rafi L., Auteur ; Mullen, Robert L., Auteur ; Zhang, Hao ; Schueller, Gerhart L., Editeur scientifique . - 1102-1111 p. Génie Civil, Génie Mécanique Langues : Anglais (eng) in Journal of engineering mechanics > Vol.131, N°10 (Octobre 2005) . - 1102-1111 p. Mots-clés : Finite  element  method  Mechanical  systems  Differential  equations  Uncertainty  principles  Méthode  d'élément  fini  Systèmes  mécaniques  Equations  Principes  d'incertitude Index. décimale : 624/621.34 Résumé : A New approach for archieving guaranteed reliable results within the context of finite-element approximation of mechanical systems is developed. A Reliable analysis requires that all the sources of uncertainty and errors be accommodated. The Appropriateness of a partial differential equation to a given physical problem is beyond the scope of this work. Parameter uncertainty is treated as intervals in this work and guaranteed bounds on the "unknown" true solutions are obtained. In this paper an element-by-element penalty-based interval finite-element analysis of linear elastic structural mechanics and solid mechanics problem is introduced. Material and load uncertainties are handled simultaneously. Presented numerical examples illustrate the ability of the method to maintain very sharp solution enclosures even when the number of the interval parameters of the size of the problems is increased. Une nouvelle approche pour réaliser des résultats fiables garantis dans le contexte de l'approximation d'fini-élément des systèmes mécaniques est développée. Une analyse fiable exige que toutes les sources de l'incertitude et des erreurs soient adaptées. La convenance d'une équation partielle à un problème physique donné est au delà de la portée de ce travail. L'incertitude de paramètre est traitée pendant que des intervalles dans ce travail et les limites garanties sur les solutions vraies "inconnues" sont obtenus. En cet article un élément-par-élément pénalité-basé analyse d'fini-élément d'intervalle de mécanique structurale élastique linéaire et de problème de mécanique des solides est présenté. Des incertitudes de matériel et de charge sont manipulées simultanément. Les exemples numériques présentés illustrent la capacité de la méthode de maintenir des clôtures très pointues de solution même lorsque le nombre de paramètres d'intervalle de la taille des problèmes est augmenté.

Using screening test results to predict the effective viscosity of swollen superabsorbent polymer particles extrusion through an open fracture / Zhang, Hao in Industrial & engineering chemistry research, Vol. 49 N° 23 (Décembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 23 (Décembre 2010) . - pp. 12284–12293 Titre : Using screening test results to predict the effective viscosity of swollen superabsorbent polymer particles extrusion through an open fracture Type de document : texte imprimé Auteurs : Zhang, Hao, Auteur ; Rajesh S. Challa, Auteur ; Baojun Bai, Auteur Année de publication : 2011 Article en page(s) : pp. 12284–12293 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Viscosity  Polymer Résumé : Superabsorbent polymer particles, also called preformed particle gels (PPGs), have been successfully applied to reduce water production and enhance oil production in mature reservoirs with fractures or super-high-permeability streaks/channels. The applied particles usually range in size from a few hundred micrometers to a few millimeters and are irregular in shape, which make it impossible to measure their rheology behavior using a traditional rheometer. A simple method, a screen model test, was designed to evaluate the rheological behavior of the swollen PPG. The results show that a swollen PPG is a shear-thinning material with properties that can be expressed using a power-law equation from which an apparent consistency constant and an apparent flow index can be obtained. Considering the shear-thinning properties, we first developed a theoretical mathematical model using a general power-law equation to predict the pressure gradient of a swollen PPG during its extrusion through a fracture. Then, we modified the model by correlating screen test results with fracture experiment results so that the apparent consistency constant and the apparent flow index obtained from the screen tests were introduced to replace the consistency constant and flow index from the general power-law equation. These equations correlated effective viscosity with flow rate, fracture width, apparent consistency constant, and apparent flow index together. The newly developed correlations were validated, and the results showed that a single group of screen test measurements can be applied to determine the effective viscosity of a PPG in a fracture with limited errors. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100917m [article] Using screening test results to predict the effective viscosity of swollen superabsorbent polymer particles extrusion through an open fracture [texte imprimé] / Zhang, Hao, Auteur ; Rajesh S. Challa, Auteur ; Baojun Bai, Auteur . - 2011 . - pp. 12284–12293. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 23 (Décembre 2010) . - pp. 12284–12293 Mots-clés : Viscosity  Polymer Résumé : Superabsorbent polymer particles, also called preformed particle gels (PPGs), have been successfully applied to reduce water production and enhance oil production in mature reservoirs with fractures or super-high-permeability streaks/channels. The applied particles usually range in size from a few hundred micrometers to a few millimeters and are irregular in shape, which make it impossible to measure their rheology behavior using a traditional rheometer. A simple method, a screen model test, was designed to evaluate the rheological behavior of the swollen PPG. The results show that a swollen PPG is a shear-thinning material with properties that can be expressed using a power-law equation from which an apparent consistency constant and an apparent flow index can be obtained. Considering the shear-thinning properties, we first developed a theoretical mathematical model using a general power-law equation to predict the pressure gradient of a swollen PPG during its extrusion through a fracture. Then, we modified the model by correlating screen test results with fracture experiment results so that the apparent consistency constant and the apparent flow index obtained from the screen tests were introduced to replace the consistency constant and flow index from the general power-law equation. These equations correlated effective viscosity with flow rate, fracture width, apparent consistency constant, and apparent flow index together. The newly developed correlations were validated, and the results showed that a single group of screen test measurements can be applied to determine the effective viscosity of a PPG in a fracture with limited errors. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100917m