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Performance assessment for a class of nonlinear systems / Zhi Zhang in Industrial & engineering chemistry research, Vol. 50 N° 18 (Septembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10557-10566 Titre : Performance assessment for a class of nonlinear systems Type de document : texte imprimé Auteurs : Zhi Zhang, Auteur ; Li-Sheng Hu, Auteur ; Xue-Lian Zhang, Auteur Année de publication : 2011 Article en page(s) : pp. 10557-10566 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Non  linear  system Résumé : In this paper, a class of specified nonlinear systems are concerned. The nonlinear process model can be considered as a simplified Kolmogorov―Gabor polynomial model, which is motivated by considering the actuator nonlinearity and the process output nonlinearity. In terms of this nonlinear system, the analytical performance benchmark and the associated benchmark controller are established by minimizing the variance of the measurement output The existence conditions of feedback invariant are discussed. The calculation of performance index, based on correlation analysis, is proposed. To facilitate assessment, a filtering or whitening method is presented. The white noise sequence is estimated by dynamic principal component analysis (DPCA), based on the nonlinear autoregressive exogenous (NARX) model. The numerical examples are given to illustrate the effectiveness of the proposed assessment method. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523878 [article] Performance assessment for a class of nonlinear systems [texte imprimé] / Zhi Zhang, Auteur ; Li-Sheng Hu, Auteur ; Xue-Lian Zhang, Auteur . - 2011 . - pp. 10557-10566. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10557-10566 Mots-clés : Non  linear  system Résumé : In this paper, a class of specified nonlinear systems are concerned. The nonlinear process model can be considered as a simplified Kolmogorov―Gabor polynomial model, which is motivated by considering the actuator nonlinearity and the process output nonlinearity. In terms of this nonlinear system, the analytical performance benchmark and the associated benchmark controller are established by minimizing the variance of the measurement output The existence conditions of feedback invariant are discussed. The calculation of performance index, based on correlation analysis, is proposed. To facilitate assessment, a filtering or whitening method is presented. The white noise sequence is estimated by dynamic principal component analysis (DPCA), based on the nonlinear autoregressive exogenous (NARX) model. The numerical examples are given to illustrate the effectiveness of the proposed assessment method. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523878

Prediction and measurement of axial flow fan aerodynamic and aeroacoustic performance in a split-type air-conditioner outdoor unit / Xifeng Zhao in International journal of refrigeration, Vol. 36 N° 3 (Mai 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 1098–1108 Titre : Prediction and measurement of axial flow fan aerodynamic and aeroacoustic performance in a split-type air-conditioner outdoor unit Titre original : Prévisions et mesures de la performance aérodynamique et aéroacoustique du ventilateur axial d'un système extérieur de conditionnement d'air de type split Type de document : texte imprimé Auteurs : Xifeng Zhao, Auteur ; Jinju Sun, Auteur ; Zhi Zhang, Auteur Année de publication : 2013 Article en page(s) : pp. 1098–1108 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Air  conditioner;  Outdoor  unit;  Axial  flow  fan;  Computational  fluid  dynamics;  Computational  aerodynamic  acoustics;  Noise  reduction Résumé : The study has focused on outdoor unit noise reduction by fan geometry modification with the refined numerical and experimental approaches. The outlet louver, electric motor and its support are included to refine the flow and acoustic model and a hybrid method incorporating CFD and CAA is used to predict the noise behavior. The fan performance curve is well-predicted; the moderate acoustic power is obtained on the outlet louver, motor support and motor exhibiting a significant contribution to overall noise behavior. The aeroacoustic test is conducted in an anechoic chamber and the obtained results are compared with the semi-anechoic chamber ones, and the unremarkable differences are produced, which indicate the ground floor being of some influence. Both modified fan geometries are effective to reduce the noise but the flanging outer-edge blade is more effective. The noise directivities of three geometry fans are investigated both numerically and experimentally and the produced asymmetric characteristics are analyzed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003325 [article] Prediction and measurement of axial flow fan aerodynamic and aeroacoustic performance in a split-type air-conditioner outdoor unit = Prévisions et mesures de la performance aérodynamique et aéroacoustique du ventilateur axial d'un système extérieur de conditionnement d'air de type split [texte imprimé] / Xifeng Zhao, Auteur ; Jinju Sun, Auteur ; Zhi Zhang, Auteur . - 2013 . - pp. 1098–1108. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 1098–1108 Mots-clés : Air  conditioner;  Outdoor  unit;  Axial  flow  fan;  Computational  fluid  dynamics;  Computational  aerodynamic  acoustics;  Noise  reduction Résumé : The study has focused on outdoor unit noise reduction by fan geometry modification with the refined numerical and experimental approaches. The outlet louver, electric motor and its support are included to refine the flow and acoustic model and a hybrid method incorporating CFD and CAA is used to predict the noise behavior. The fan performance curve is well-predicted; the moderate acoustic power is obtained on the outlet louver, motor support and motor exhibiting a significant contribution to overall noise behavior. The aeroacoustic test is conducted in an anechoic chamber and the obtained results are compared with the semi-anechoic chamber ones, and the unremarkable differences are produced, which indicate the ground floor being of some influence. Both modified fan geometries are effective to reduce the noise but the flanging outer-edge blade is more effective. The noise directivities of three geometry fans are investigated both numerically and experimentally and the produced asymmetric characteristics are analyzed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003325