Documents disponibles écrits par cet auteur

Analytical approach to predicting temperature fields in multilayered pavement systems / Dong Wang in Journal of engineering mechanics, Vol. 135 N° 4 (Avril 2009) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 135 N° 4 (Avril 2009) . - pp. 334-344 Titre : Analytical approach to predicting temperature fields in multilayered pavement systems Type de document : texte imprimé Auteurs : Dong Wang, Auteur ; Jeffery R. Roesler, Auteur ; Da-Zhi Guo, Auteur Article en page(s) : pp. 334-344 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Temperature  distribution  Layered  systems  Flexible  pavements  Rigid  pavements  Heat  transfer  Temperature  effects. Résumé : An accurate and rapid estimation of the pavement temperature field is desired to better predict pavement responses and for pavement system design. In this paper, an innovative method to derive the theoretical solution of an axisymmetric temperature field in a multilayered pavement system is presented. The multilayered pavement system was modeled as a two-dimensional heat transfer problem. The temperature at any location (r,z) and any time t in an N-layer pavement system can be calculated by using the derived analytical solution. The Hankel integral transform with respect to the radial coordinate is utilized in the derivation of the solution. The interpolatory trigonometric polynomials based on discrete Fourier transform are used to fit the measured air temperatures and solar radiation intensities during a day, which are essential components in the boundary condition for the underlying heat transfer problem. A FORTRAN program was coded to implement this analytical solution. Measured field temperature results from a rigid pavement system demonstrate that the derived analytical solution generates reasonable temperature profiles in the concrete slab. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...] [article] Analytical approach to predicting temperature fields in multilayered pavement systems [texte imprimé] / Dong Wang, Auteur ; Jeffery R. Roesler, Auteur ; Da-Zhi Guo, Auteur . - pp. 334-344. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 135 N° 4 (Avril 2009) . - pp. 334-344 Mots-clés : Temperature  distribution  Layered  systems  Flexible  pavements  Rigid  pavements  Heat  transfer  Temperature  effects. Résumé : An accurate and rapid estimation of the pavement temperature field is desired to better predict pavement responses and for pavement system design. In this paper, an innovative method to derive the theoretical solution of an axisymmetric temperature field in a multilayered pavement system is presented. The multilayered pavement system was modeled as a two-dimensional heat transfer problem. The temperature at any location (r,z) and any time t in an N-layer pavement system can be calculated by using the derived analytical solution. The Hankel integral transform with respect to the radial coordinate is utilized in the derivation of the solution. The interpolatory trigonometric polynomials based on discrete Fourier transform are used to fit the measured air temperatures and solar radiation intensities during a day, which are essential components in the boundary condition for the underlying heat transfer problem. A FORTRAN program was coded to implement this analytical solution. Measured field temperature results from a rigid pavement system demonstrate that the derived analytical solution generates reasonable temperature profiles in the concrete slab. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...]

Design and Fluid Dynamic Analysis of a Three-Fluidized-Bed Reactor System for Chemical-Looping Hydrogen Generation / Zhipeng Xue in Industrial & engineering chemistry research, Vol. 51 N° 11 (Mars 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 11 (Mars 2012) . - pp. 4267–4278 Titre : Design and Fluid Dynamic Analysis of a Three-Fluidized-Bed Reactor System for Chemical-Looping Hydrogen Generation Type de document : texte imprimé Auteurs : Zhipeng Xue, Auteur ; Shiyi Chen, Auteur ; Dong Wang, Auteur Année de publication : 2012 Article en page(s) : pp. 4267–4278 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluid  dynamic  Hydrogen Résumé : Chemical-looping hydrogen generation (CLHG) can produce hydrogen from fossils fuels with inherent separation of CO2. Iron oxide is a suitable oxygen carrier for this process. The CLHG process basically involves three reactors, a fuel reactor (FR), a steam reactor (SR), and an air reactor (AR). In the FR, the carbon-containing fuel gases react with hematite (Fe2O3). The product solids are wüstite (FeO), and the product stream is a mixture of carbon dioxide and water vapor. After water condensation, pure carbon dioxide can be obtained. FeO then enters the SR and react with steam, giving the gas product hydrogen and the solid product magnetite (Fe3O4). In the AR, Fe3O4 is reoxidized to Fe2O3. Through this cycle, hydrogen is generated with inherent separation of CO2. In this article, a novel compact fluidized-bed fuel reactor is proposed. It integrates a bubbling fluidized bed and a riser to obtain full conversion of unreacted fuel gases through the thermodynamic equilibrium limit. Based on this fuel reactor, a cold-flow model of the three-fluidized-bed reactor system with a 50-kW CLHG design scheme was built to test the feasibility of this CLHG process. A series of tests with respect to solids circulation rate, gas leakage, and stability of long-term operation were performed by varying the inlet gas flow and total solids inventory. The results showed that the three-fluidized-bed reactor system can run steadily. The solids circulation rate could be changed in a wide range by adjusting the inlet gas flows. The gas leakage was associated with both the solids circulation rate and the pressure difference balanced by the downcomer. The system showed a stable pressure difference and solids circulation rate during a test of long-term operation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201052r?mi=tei08o&af=R&pageSize=20&searchT [...] [article] Design and Fluid Dynamic Analysis of a Three-Fluidized-Bed Reactor System for Chemical-Looping Hydrogen Generation [texte imprimé] / Zhipeng Xue, Auteur ; Shiyi Chen, Auteur ; Dong Wang, Auteur . - 2012 . - pp. 4267–4278. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 11 (Mars 2012) . - pp. 4267–4278 Mots-clés : Fluid  dynamic  Hydrogen Résumé : Chemical-looping hydrogen generation (CLHG) can produce hydrogen from fossils fuels with inherent separation of CO2. Iron oxide is a suitable oxygen carrier for this process. The CLHG process basically involves three reactors, a fuel reactor (FR), a steam reactor (SR), and an air reactor (AR). In the FR, the carbon-containing fuel gases react with hematite (Fe2O3). The product solids are wüstite (FeO), and the product stream is a mixture of carbon dioxide and water vapor. After water condensation, pure carbon dioxide can be obtained. FeO then enters the SR and react with steam, giving the gas product hydrogen and the solid product magnetite (Fe3O4). In the AR, Fe3O4 is reoxidized to Fe2O3. Through this cycle, hydrogen is generated with inherent separation of CO2. In this article, a novel compact fluidized-bed fuel reactor is proposed. It integrates a bubbling fluidized bed and a riser to obtain full conversion of unreacted fuel gases through the thermodynamic equilibrium limit. Based on this fuel reactor, a cold-flow model of the three-fluidized-bed reactor system with a 50-kW CLHG design scheme was built to test the feasibility of this CLHG process. A series of tests with respect to solids circulation rate, gas leakage, and stability of long-term operation were performed by varying the inlet gas flow and total solids inventory. The results showed that the three-fluidized-bed reactor system can run steadily. The solids circulation rate could be changed in a wide range by adjusting the inlet gas flows. The gas leakage was associated with both the solids circulation rate and the pressure difference balanced by the downcomer. The system showed a stable pressure difference and solids circulation rate during a test of long-term operation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201052r?mi=tei08o&af=R&pageSize=20&searchT [...]

Keying of rectangular plate anchors in normally consolidated clays / Dong Wang in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 12 (Décembre 2011) . - pp. 1244-1253 Titre : Keying of rectangular plate anchors in normally consolidated clays Type de document : texte imprimé Auteurs : Dong Wang, Auteur ; Yuxia Hu, Auteur ; Mark F. Randolph, Auteur Année de publication : 2012 Article en page(s) : pp. 1244-1253 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Finite-element  method  Plate  anchor  Uplift  capacity  Normally  consolidated  clay  Keying  Large  deformation  analysis Résumé : The loss in anchor embedment during keying, as it rotates to become normal to the cable load, reduces the uplift capacity of anchors in normally consolidated clay. The keying behavior of plate anchors has been studied previously by using centrifuge and field model tests. In this paper, a large deformation finite-element approach incorporating frequent mesh regeneration and allowing for evolution of the anchor-chain profile, was developed to simulate the keying process of rectangular and strip plate anchors. A parametric study was undertaken to quantify the loss in anchor embedment during keying in terms of the anchor geometry, soil properties, loading eccentricity, and inclination. The embedment loss decreased dramatically with increasing loading eccentricity and decreasing chain angle at the mudline to the horizontal. The loss in anchor embedment during keying increased as the local soil strength increased relative to the weight of the anchor, up to a limit determined by the eccentricity of loading. In contrast, the effect of the soil strength gradient was minimal. Findings of this study yield a recommendation that the most important factor in anchor keying, loading eccentricity, should not be less than half the anchor width for an effective design. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i12/p1244_s1?isAuthorized=no [article] Keying of rectangular plate anchors in normally consolidated clays [texte imprimé] / Dong Wang, Auteur ; Yuxia Hu, Auteur ; Mark F. Randolph, Auteur . - 2012 . - pp. 1244-1253. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 12 (Décembre 2011) . - pp. 1244-1253 Mots-clés : Finite-element  method  Plate  anchor  Uplift  capacity  Normally  consolidated  clay  Keying  Large  deformation  analysis Résumé : The loss in anchor embedment during keying, as it rotates to become normal to the cable load, reduces the uplift capacity of anchors in normally consolidated clay. The keying behavior of plate anchors has been studied previously by using centrifuge and field model tests. In this paper, a large deformation finite-element approach incorporating frequent mesh regeneration and allowing for evolution of the anchor-chain profile, was developed to simulate the keying process of rectangular and strip plate anchors. A parametric study was undertaken to quantify the loss in anchor embedment during keying in terms of the anchor geometry, soil properties, loading eccentricity, and inclination. The embedment loss decreased dramatically with increasing loading eccentricity and decreasing chain angle at the mudline to the horizontal. The loss in anchor embedment during keying increased as the local soil strength increased relative to the weight of the anchor, up to a limit determined by the eccentricity of loading. In contrast, the effect of the soil strength gradient was minimal. Findings of this study yield a recommendation that the most important factor in anchor keying, loading eccentricity, should not be less than half the anchor width for an effective design. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i12/p1244_s1?isAuthorized=no

Role of A (A = Ca, Mg, Sr) over hexaaluminates La0.8A0.2NiAl11O19 for carbon dioxide reforming of methane / Jing Li in Industrial & engineering chemistry research, Vol. 50 N° 19 (Octobre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 10955-10961 Titre : Role of A (A = Ca, Mg, Sr) over hexaaluminates La0.8A0.2NiAl11O19 for carbon dioxide reforming of methane Type de document : texte imprimé Auteurs : Jing Li, Auteur ; Dong Wang, Auteur ; Guangdong Zhou, Auteur Année de publication : 2011 Article en page(s) : pp. 10955-10961 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Reforming  Carbon  dioxide Résumé : A study on hexaaluminates La0.8A0.2NiAl11O19 (A= Ca, Mg, Sr) as catalysts for CO2 reforming of CH4 was carried out by means of the XRD, TPR, TGA, XPS, and TEM techniques. It was found that the active Ni dispersion and Ni particle size depend strongly on the ionic radius of the alkaline earth metal (Ca, Mg, Sr). The ionic radius of Ca is less than that of La, and the difference between the ionic radii of Ca and La is lowest. The La0.8Ca0.2NiAl11O19 catalyst exhibited the highest activity compared to those of the other two catalysts, and it also showed a remarkably low carbon deposition. The presence of two types of carbon (deactivating encapsulating carbon and nondeactivating filamentous carbon) was observed by TEM. The filamentous carbon formed more easily over the La0.8Ca0.2NiAl11O19 catalyst. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24573290 [article] Role of A (A = Ca, Mg, Sr) over hexaaluminates La0.8A0.2NiAl11O19 for carbon dioxide reforming of methane [texte imprimé] / Jing Li, Auteur ; Dong Wang, Auteur ; Guangdong Zhou, Auteur . - 2011 . - pp. 10955-10961. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 10955-10961 Mots-clés : Reforming  Carbon  dioxide Résumé : A study on hexaaluminates La0.8A0.2NiAl11O19 (A= Ca, Mg, Sr) as catalysts for CO2 reforming of CH4 was carried out by means of the XRD, TPR, TGA, XPS, and TEM techniques. It was found that the active Ni dispersion and Ni particle size depend strongly on the ionic radius of the alkaline earth metal (Ca, Mg, Sr). The ionic radius of Ca is less than that of La, and the difference between the ionic radii of Ca and La is lowest. The La0.8Ca0.2NiAl11O19 catalyst exhibited the highest activity compared to those of the other two catalysts, and it also showed a remarkably low carbon deposition. The presence of two types of carbon (deactivating encapsulating carbon and nondeactivating filamentous carbon) was observed by TEM. The filamentous carbon formed more easily over the La0.8Ca0.2NiAl11O19 catalyst. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24573290

Three-dimensional large deformation finite-element analysis of plate anchors in uniform clay / Dong Wang in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 2 (Fevrier 2010) . - pp. 355-365 Titre : Three-dimensional large deformation finite-element analysis of plate anchors in uniform clay Type de document : texte imprimé Auteurs : Dong Wang, Auteur ; Yuxia Hu, Auteur ; Mark F. Randolph, Auteur Article en page(s) : pp. 355-365 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Anchors  Soil  deformation  Finite-element  method  Clays  Three-dimensional  analysis Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Three-dimensional large deformation finite-element (FE) analyses were performed to investigate plate anchor capacity during vertical pullout. The remeshing and interpolation technique with small strain approach was expanded from two-dimensional to three-dimensional conditions and coupled with the FE software, ABAQUS. A modified recovery of equilibrium in patches technique was developed to map stresses after each remeshing. Continuous pullout of rectangular plate anchors was simulated and the large deformation results for strip, circular, and rectangular anchors were compared with model test data, small strain FE results, and plastic limit solutions. Interface conditions of no breakaway (bonded) and immediate breakaway (no tension) were considered at the anchor base. The effects of anchor roughness, aspect ratio, soil properties, and soil overburden pressure were investigated. It was found that the anchor roughness had minimal effect on anchor performance. For square and circular deep anchors under immediate breakaway conditions, the maximum uplift capacity increased with soil elastic modulus, which suggests that lower bound limit analysis and small strain FE analysis may overestimate the capacity. The soil beneath the anchor base separates from the anchor at a certain embedment depth near the mudline, once tensile stresses were generated. The ratio of separation depth to anchor width was found to increase linearly with the ratio of soil undrained shear strength to the product of soil effective unit weight and anchor width and was independent of the initial anchor embedment depth. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...] [article] Three-dimensional large deformation finite-element analysis of plate anchors in uniform clay [texte imprimé] / Dong Wang, Auteur ; Yuxia Hu, Auteur ; Mark F. Randolph, Auteur . - pp. 355-365. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 2 (Fevrier 2010) . - pp. 355-365 Mots-clés : Anchors  Soil  deformation  Finite-element  method  Clays  Three-dimensional  analysis Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Three-dimensional large deformation finite-element (FE) analyses were performed to investigate plate anchor capacity during vertical pullout. The remeshing and interpolation technique with small strain approach was expanded from two-dimensional to three-dimensional conditions and coupled with the FE software, ABAQUS. A modified recovery of equilibrium in patches technique was developed to map stresses after each remeshing. Continuous pullout of rectangular plate anchors was simulated and the large deformation results for strip, circular, and rectangular anchors were compared with model test data, small strain FE results, and plastic limit solutions. Interface conditions of no breakaway (bonded) and immediate breakaway (no tension) were considered at the anchor base. The effects of anchor roughness, aspect ratio, soil properties, and soil overburden pressure were investigated. It was found that the anchor roughness had minimal effect on anchor performance. For square and circular deep anchors under immediate breakaway conditions, the maximum uplift capacity increased with soil elastic modulus, which suggests that lower bound limit analysis and small strain FE analysis may overestimate the capacity. The soil beneath the anchor base separates from the anchor at a certain embedment depth near the mudline, once tensile stresses were generated. The ratio of separation depth to anchor width was found to increase linearly with the ratio of soil undrained shear strength to the product of soil effective unit weight and anchor width and was independent of the initial anchor embedment depth. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...]