Documents disponibles écrits par cet auteur

Sensitivity of the human comfort equation and of free convection in a vertical enclosure as examples of the use of global sensitivity to evaluate parameter interactions / A. F. Emery in Journal of heat transfer, Vol. 132 N° 1 (Janvier 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 1 (Janvier 2010) . - pp. [012501-1/10] Titre : Sensitivity of the human comfort equation and of free convection in a vertical enclosure as examples of the use of global sensitivity to evaluate parameter interactions Type de document : texte imprimé Auteurs : A. F. Emery, Auteur ; M.-H. H. Wu, Auteur ; A. M. Mescher, Auteur Article en page(s) : pp. [012501-1/10] Note générale : Physique Langues : Anglais (eng) Mots-clés : Sensitivity  Global  sensitivity  Interactions  Uncertainty  Free  convection  Human  confort Index. décimale : 536 Chaleur. Thermodynamique Résumé : Many models of engineering and scientific systems involve interactions between and among the parameters, stimuli, and physical properties. The determination of the adequacy of models for predictions and for designing experiments generally involves sensitivity studies. Good designs mandate that the experiments be sensitive to the parameters sought with little interaction between them because such interaction generally confuses the estimation and reduces the precision of the estimates. For design purposes, analysts frequently want to evaluate the sensitivities of the predicted responses to specific variables, but if the variables interact it is often difficult to separate the effects. Global sensitivity is a technique by which one can evaluate the magnitude of the interactions between multiple variables. In this paper, the global sensitivity approach is applied to the human comfort equation and to free convection in a rectangular enclosure. It is found that when occupants are uncomfortable, there is little interaction and that one can predict the effects of changing several environmental conditions at once by adding the separate effects. But when occupants are comfortable, there is a large interaction and the effects cannot be treated separately. Free convective heat transfer in an enclosure is a function of the Rayleigh number Ra and the aspect ratio H/W, and the flow field changes from unicellular to multicellular as Ra increases. There is a strong interaction for H/W<=2 but little for H/W>=2. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Sensitivity of the human comfort equation and of free convection in a vertical enclosure as examples of the use of global sensitivity to evaluate parameter interactions [texte imprimé] / A. F. Emery, Auteur ; M.-H. H. Wu, Auteur ; A. M. Mescher, Auteur . - pp. [012501-1/10]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 1 (Janvier 2010) . - pp. [012501-1/10] Mots-clés : Sensitivity  Global  sensitivity  Interactions  Uncertainty  Free  convection  Human  confort Index. décimale : 536 Chaleur. Thermodynamique Résumé : Many models of engineering and scientific systems involve interactions between and among the parameters, stimuli, and physical properties. The determination of the adequacy of models for predictions and for designing experiments generally involves sensitivity studies. Good designs mandate that the experiments be sensitive to the parameters sought with little interaction between them because such interaction generally confuses the estimation and reduces the precision of the estimates. For design purposes, analysts frequently want to evaluate the sensitivities of the predicted responses to specific variables, but if the variables interact it is often difficult to separate the effects. Global sensitivity is a technique by which one can evaluate the magnitude of the interactions between multiple variables. In this paper, the global sensitivity approach is applied to the human comfort equation and to free convection in a rectangular enclosure. It is found that when occupants are uncomfortable, there is little interaction and that one can predict the effects of changing several environmental conditions at once by adding the separate effects. But when occupants are comfortable, there is a large interaction and the effects cannot be treated separately. Free convective heat transfer in an enclosure is a function of the Rayleigh number Ra and the aspect ratio H/W, and the flow field changes from unicellular to multicellular as Ra increases. There is a strong interaction for H/W<=2 but little for H/W>=2. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

The effect of spatially correlated roughness and boundary conditions on the conduction of heat through a slab / A. F. Emery in Journal of heat transfer, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 5 (Mai 2010) . - pp. [051301-1/11] Titre : The effect of spatially correlated roughness and boundary conditions on the conduction of heat through a slab Type de document : texte imprimé Auteurs : A. F. Emery, Auteur ; H. Dillon, Auteur ; A. M. Mescher, Auteur Article en page(s) : pp. [051301-1/11] Note générale : Physique Langues : Anglais (eng) Mots-clés : Surface  roughness  Correlated  boundary  conditions  Stochastic  conduction  Uncertainty Index. décimale : 536 Chaleur. Thermodynamique Résumé : The nominally one-dimensional conduction of heat through a slab becomes two dimensional when one of the surfaces is rough or when the boundary conditions are spatially nonuniform. This paper develops the stochastic equations for a slab whose surface roughness or convective boundary condition is spatially correlated with correlation lengths ranging from 0 (white noise) to a length long in comparison to the slab thickness. The effect is described in terms of the standard deviation and the resulting spatial correlation of the heat flux as a function of depth into the slab. In contrast to the expectation that the effect is monotonic with respect to the correlation length, it is shown that the effect is maximized at an intermediate correlation length. It is also shown that roughness or a random convective heat transfer coefficient have essentially the same effects on the conducted heat, but that the combination results in a much deeper penetration than does each effect individually. In contrast to the usual methods of solving stochastic problems, both the case of a rough edge and a smooth edge with stochastic convective heat transfer coefficients can only be treated with reasonable computational expense by using direct Monte Carlo simulations. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&smode=strresults& [...] [article] The effect of spatially correlated roughness and boundary conditions on the conduction of heat through a slab [texte imprimé] / A. F. Emery, Auteur ; H. Dillon, Auteur ; A. M. Mescher, Auteur . - pp. [051301-1/11]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 5 (Mai 2010) . - pp. [051301-1/11] Mots-clés : Surface  roughness  Correlated  boundary  conditions  Stochastic  conduction  Uncertainty Index. décimale : 536 Chaleur. Thermodynamique Résumé : The nominally one-dimensional conduction of heat through a slab becomes two dimensional when one of the surfaces is rough or when the boundary conditions are spatially nonuniform. This paper develops the stochastic equations for a slab whose surface roughness or convective boundary condition is spatially correlated with correlation lengths ranging from 0 (white noise) to a length long in comparison to the slab thickness. The effect is described in terms of the standard deviation and the resulting spatial correlation of the heat flux as a function of depth into the slab. In contrast to the expectation that the effect is monotonic with respect to the correlation length, it is shown that the effect is maximized at an intermediate correlation length. It is also shown that roughness or a random convective heat transfer coefficient have essentially the same effects on the conducted heat, but that the combination results in a much deeper penetration than does each effect individually. In contrast to the usual methods of solving stochastic problems, both the case of a rough edge and a smooth edge with stochastic convective heat transfer coefficients can only be treated with reasonable computational expense by using direct Monte Carlo simulations. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&smode=strresults& [...]