Optimal design and operation of a spatially distributed multiscale process, with regard to layered heterostructure growth / Christopher M. Behrens in Industrial & engineering chemistry research, Vol. 49 N° 17 (Septembre 1, 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 17 (Septembre 1, 2010) . - pp 7891–7900 Titre : Optimal design and operation of a spatially distributed multiscale process, with regard to layered heterostructure growth Type de document : texte imprimé Auteurs : Christopher M. Behrens, Auteur ; Antonios Armaou, Auteur Année de publication : 2010 Article en page(s) : pp 7891–7900 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Optimal design Multiscale process Heterostructure. Résumé : Determining the optimal operation of processes modeled by multiscale systems presents many challenges, because of complexities in modeling and the extensive computational requirements needed to solve them. Application to layered heterostructure deposition is considered here, where an additional challenge of interface characterization is encountered. A solution methodology is applied to the fabrication of a device consisting of alternating layers of gallium arsenide and aluminum arsenide, with the intent of minimizing thickness nonuniformity and interfacial step density. Using a finite-element solver and kinetic Monte Carlo simulations, we were able to balance reductions in thickness nonuniformity and interfacial step density with maintaining favorable operating conditions in a computationally efficient manner. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9020107 [article] Optimal design and operation of a spatially distributed multiscale process, with regard to layered heterostructure growth [texte imprimé] / Christopher M. Behrens, Auteur ; Antonios Armaou, Auteur . - 2010 . - pp 7891–7900. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 17 (Septembre 1, 2010) . - pp 7891–7900 Mots-clés : Optimal design Multiscale process Heterostructure. Résumé : Determining the optimal operation of processes modeled by multiscale systems presents many challenges, because of complexities in modeling and the extensive computational requirements needed to solve them. Application to layered heterostructure deposition is considered here, where an additional challenge of interface characterization is encountered. A solution methodology is applied to the fabrication of a device consisting of alternating layers of gallium arsenide and aluminum arsenide, with the intent of minimizing thickness nonuniformity and interfacial step density. Using a finite-element solver and kinetic Monte Carlo simulations, we were able to balance reductions in thickness nonuniformity and interfacial step density with maintaining favorable operating conditions in a computationally efficient manner. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9020107

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Output feedback control of distributed parameter systems using adaptive proper orthogonal decomposition / Sivakumar Pitchaiah in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10496–10509 Titre : Output feedback control of distributed parameter systems using adaptive proper orthogonal decomposition Type de document : texte imprimé Auteurs : Sivakumar Pitchaiah, Auteur ; Antonios Armaou, Auteur Année de publication : 2011 Article en page(s) : pp. 10496–10509 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Feedback Orthogonal decomposition Résumé : We address the problem of tracking and stabilization of dissipative distributed parameter systems, by designing static output feedback controllers using adaptive proper orthogonal decomposition methodology (APOD). Initially, an ensemble of eigenfunctions is constructed based on a relatively small data ensemble which is then recursively updated as additional process data becomes available periodically. The proposed APOD methodology relaxes the need for a representative ensemble of snapshots (in the sense that it contains the global dynamics of the process). An accurate reduced-order model (ROM) is constructed and periodically refined based on these updated eigenfunctions. Using the ROM and continuous measurements available from the restricted number of sensors, a static output feedback controller is subsequently designed. This controller is successfully used to achieve the desired control objective of stabilization and tracking in the Kuramoto−Sivashinksy and FitzHugh−Nagumo equations. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100463f [article] Output feedback control of distributed parameter systems using adaptive proper orthogonal decomposition [texte imprimé] / Sivakumar Pitchaiah, Auteur ; Antonios Armaou, Auteur . - 2011 . - pp. 10496–10509. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10496–10509 Mots-clés : Feedback Orthogonal decomposition Résumé : We address the problem of tracking and stabilization of dissipative distributed parameter systems, by designing static output feedback controllers using adaptive proper orthogonal decomposition methodology (APOD). Initially, an ensemble of eigenfunctions is constructed based on a relatively small data ensemble which is then recursively updated as additional process data becomes available periodically. The proposed APOD methodology relaxes the need for a representative ensemble of snapshots (in the sense that it contains the global dynamics of the process). An accurate reduced-order model (ROM) is constructed and periodically refined based on these updated eigenfunctions. Using the ROM and continuous measurements available from the restricted number of sensors, a static output feedback controller is subsequently designed. This controller is successfully used to achieve the desired control objective of stabilization and tracking in the Kuramoto−Sivashinksy and FitzHugh−Nagumo equations. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100463f

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