Documents disponibles écrits par cet auteur

Decentralized Hscrinfin controller design for large-scale civil structures / Yang Wang in Earthquake engineering structural dynamics, Vol. 38 N°3 (Mars 2009) 

Public ISBD [article]  in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 377-401 Titre : Decentralized Hscrinfin controller design for large-scale civil structures Type de document : texte imprimé Auteurs : Yang Wang, Auteur ; Jerome P. Lynch, Auteur ; Kincho H. Law, Auteur Article en page(s) : pp. 377-401 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : H-infinity  control;  Feedback  structural  control;  Decentralized  control;  Smart  structures Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Complexities inherent to large-scale modern civil structures pose many challenges in the design of feedback structural control systems for dynamic response mitigation. With the emergence of low-cost sensors and control devices creating technologies from which large-scale structural control systems can deploy, a future control system may contain hundreds, or even thousands, of such devices. Key issues in such large-scale structural control systems include reduced system reliability, increasing communication requirements, and longer latencies in the feedback loop. To effectively address these issues, decentralized control strategies provide promising solutions that allow control systems to operate at high nodal counts. This paper examines the feasibility of designing a decentralized controller that minimizes the norm of the closed-loop system. control is a natural choice for decentralization because imposition of decentralized architectures is easy to achieve when posing the controller design using linear matrix inequalities. Decentralized control solutions are investigated for both continuous-time and discrete-time formulations. Numerical simulation results using a 3-story and a 20-story structure illustrate the feasibility of the different decentralized control strategies. The results also demonstrate that when realistic semi-active control devices are used in combination with the decentralized control solution, better performance can be gained over the passive control cases. It is shown that decentralized control strategies may provide equivalent or better control performance, given that their centralized counterparts could suffer from longer sampling periods due to communication and computation constraints. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121520796/abstract [article] Decentralized Hscrinfin controller design for large-scale civil structures [texte imprimé] / Yang Wang, Auteur ; Jerome P. Lynch, Auteur ; Kincho H. Law, Auteur . - pp. 377-401. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N°3 (Mars 2009) . - pp. 377-401 Mots-clés : H-infinity  control;  Feedback  structural  control;  Decentralized  control;  Smart  structures Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Complexities inherent to large-scale modern civil structures pose many challenges in the design of feedback structural control systems for dynamic response mitigation. With the emergence of low-cost sensors and control devices creating technologies from which large-scale structural control systems can deploy, a future control system may contain hundreds, or even thousands, of such devices. Key issues in such large-scale structural control systems include reduced system reliability, increasing communication requirements, and longer latencies in the feedback loop. To effectively address these issues, decentralized control strategies provide promising solutions that allow control systems to operate at high nodal counts. This paper examines the feasibility of designing a decentralized controller that minimizes the norm of the closed-loop system. control is a natural choice for decentralization because imposition of decentralized architectures is easy to achieve when posing the controller design using linear matrix inequalities. Decentralized control solutions are investigated for both continuous-time and discrete-time formulations. Numerical simulation results using a 3-story and a 20-story structure illustrate the feasibility of the different decentralized control strategies. The results also demonstrate that when realistic semi-active control devices are used in combination with the decentralized control solution, better performance can be gained over the passive control cases. It is shown that decentralized control strategies may provide equivalent or better control performance, given that their centralized counterparts could suffer from longer sampling periods due to communication and computation constraints. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121520796/abstract

Fast model predictive control using online optimization / Yang Wang in IEEE Transactions on control systems technology, Vol. 18 N° 2 (Mars 2010) 

Public ISBD [article]  in IEEE Transactions on control systems technology > Vol. 18 N° 2 (Mars 2010) . - pp. 267-278 Titre : Fast model predictive control using online optimization Type de document : texte imprimé Auteurs : Yang Wang, Auteur ; Stephen Boyd, Auteur Année de publication : 2011 Article en page(s) : pp. 267-278 Note générale : Génie Aérospatial Langues : Anglais (eng) Mots-clés : Model  predictive  control  (MPC)  Real-time  convex  optimization Index. décimale : 629.1 Résumé : A widely recognized shortcoming of model predictive control (MPC) is that it can usually only be used in applications with slow dynamics, where the sample time is measured in seconds or minutes. A well-known technique for implementing fast MPC is to compute the entire control law offline, in which case the online controller can be implemented as a lookup table. This method works well for systems with small state and input dimensions (say, no more than five), few constraints, and short time horizons. In this paper, we describe a collection of methods for improving the speed of MPC, using online optimization. These custom methods, which exploit the particular structure of the MPC problem, can compute the control action on the order of 100 times faster than a method that uses a generic optimizer. As an example, our method computes the control actions for a problem with 12 states, 3 controls, and horizon of 30 time steps (which entails solving a quadratic program with 450 variables and 1284 constraints) in around 5 ms, allowing MPC to be carried out at 200 Hz. DEWEY : 629.1 ISSN : 1063-6536 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5153127 [article] Fast model predictive control using online optimization [texte imprimé] / Yang Wang, Auteur ; Stephen Boyd, Auteur . - 2011 . - pp. 267-278. Génie Aérospatial Langues : Anglais (eng) in IEEE Transactions on control systems technology > Vol. 18 N° 2 (Mars 2010) . - pp. 267-278 Mots-clés : Model  predictive  control  (MPC)  Real-time  convex  optimization Index. décimale : 629.1 Résumé : A widely recognized shortcoming of model predictive control (MPC) is that it can usually only be used in applications with slow dynamics, where the sample time is measured in seconds or minutes. A well-known technique for implementing fast MPC is to compute the entire control law offline, in which case the online controller can be implemented as a lookup table. This method works well for systems with small state and input dimensions (say, no more than five), few constraints, and short time horizons. In this paper, we describe a collection of methods for improving the speed of MPC, using online optimization. These custom methods, which exploit the particular structure of the MPC problem, can compute the control action on the order of 100 times faster than a method that uses a generic optimizer. As an example, our method computes the control actions for a problem with 12 states, 3 controls, and horizon of 30 time steps (which entails solving a quadratic program with 450 variables and 1284 constraints) in around 5 ms, allowing MPC to be carried out at 200 Hz. DEWEY : 629.1 ISSN : 1063-6536 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5153127

Kinetic models for the coke combustion on deactivated ZSM-5/MOR derived from n-heptane cracking / Ning Zhu in Industrial & engineering chemistry research, Vol. 49 N° 1 (Janvier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 1 (Janvier 2010) . - pp. 89–93 Titre : Kinetic models for the coke combustion on deactivated ZSM-5/MOR derived from n-heptane cracking Type de document : texte imprimé Auteurs : Ning Zhu, Auteur ; Yuan-yuan Liu, Auteur ; Yang Wang, Auteur Année de publication : 2010 Article en page(s) : pp. 89–93 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Kinetic  Models--Coke--Combustion--Deactivated--ZSM-5/MOR--Derived  from  n-Heptane--Cracking Résumé : The combustion behavior of coked H−ZSM-5/H−mordenite (ZSM-5/MOR) derived from catalytic cracking of n-heptane with and without water steam has been studied by thermogravimetric analysis (TGA). Catalytic cracking under vapor atmosphere with a water−oil ratio of 2 at 650 °C created only one type of coke deposit on the catalyst. On the other hand, two types of coke can be found on the coked catalyst deactivated by catalytic cracking without water steam. These results indicated different combustion kinetic models of different types of coke. A one-coke combustion model for the regeneration of coked catalyst obtained under water steam and a two-coke combustion model for the regeneration of coked catalyst derived without water steam were conducted by using TGA, respectively. Finally, the relationship between the C/H ratios and activation energies in the combustion kinetic models were investigated by ultimate analysis. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900855y [article] Kinetic models for the coke combustion on deactivated ZSM-5/MOR derived from n-heptane cracking [texte imprimé] / Ning Zhu, Auteur ; Yuan-yuan Liu, Auteur ; Yang Wang, Auteur . - 2010 . - pp. 89–93. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 1 (Janvier 2010) . - pp. 89–93 Mots-clés : Kinetic  Models--Coke--Combustion--Deactivated--ZSM-5/MOR--Derived  from  n-Heptane--Cracking Résumé : The combustion behavior of coked H−ZSM-5/H−mordenite (ZSM-5/MOR) derived from catalytic cracking of n-heptane with and without water steam has been studied by thermogravimetric analysis (TGA). Catalytic cracking under vapor atmosphere with a water−oil ratio of 2 at 650 °C created only one type of coke deposit on the catalyst. On the other hand, two types of coke can be found on the coked catalyst deactivated by catalytic cracking without water steam. These results indicated different combustion kinetic models of different types of coke. A one-coke combustion model for the regeneration of coked catalyst obtained under water steam and a two-coke combustion model for the regeneration of coked catalyst derived without water steam were conducted by using TGA, respectively. Finally, the relationship between the C/H ratios and activation energies in the combustion kinetic models were investigated by ultimate analysis. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900855y

Thermal conductivity of electron-doped CaMnO3 perovskites / Yang Wang in Acta materialia, Vol. 58 N° 19 (Novembre 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 19 (Novembre 2010) . - pp. 6306–6316 Titre : Thermal conductivity of electron-doped CaMnO3 perovskites : Local lattice distortions and optical phonon thermal excitation Type de document : texte imprimé Auteurs : Yang Wang, Auteur ; Yu Sui, Auteur ; Xianjie Wang, Auteur Année de publication : 2011 Article en page(s) : pp. 6306–6316 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Manganite  perovskite  Thermal  conductivity  Spin-phonon  scattering  MnO6  distortion  Optical  phonon Résumé : The thermal transport properties of a series of electron-doped CaMnO3 perovskites have been investigated. Throughout the temperature range 5–300 K, phonon thermal conductivity is dominant, and both electron and spin wave contributions are negligible. The short phonon mean free paths in this system result in the relatively low thermal conductivities. The strong phonon scatterings stem from the A-site mismatch and bond-length fluctuations induced by local distortions of MnO6 octahedra. The thermal conductivity in the magnetically ordered state is enhanced as a result of the decrease in spin–phonon scattering. The results also indicate that above the magnetic ordering temperature, observable thermal excitation of optical phonons occurs. The contribution of optical phonons to thermal conductivity becomes non-negligible and is proposed to play an important role in the glass-like thermal transport behavior (i.e. positive temperature dependence of the thermal conductivity) in the paramagnetic state. These features can be understood in terms of an expression of thermal conductivity that includes both acoustic and optical phonon terms. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410004969 [article] Thermal conductivity of electron-doped CaMnO3 perovskites : Local lattice distortions and optical phonon thermal excitation [texte imprimé] / Yang Wang, Auteur ; Yu Sui, Auteur ; Xianjie Wang, Auteur . - 2011 . - pp. 6306–6316. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 19 (Novembre 2010) . - pp. 6306–6316 Mots-clés : Manganite  perovskite  Thermal  conductivity  Spin-phonon  scattering  MnO6  distortion  Optical  phonon Résumé : The thermal transport properties of a series of electron-doped CaMnO3 perovskites have been investigated. Throughout the temperature range 5–300 K, phonon thermal conductivity is dominant, and both electron and spin wave contributions are negligible. The short phonon mean free paths in this system result in the relatively low thermal conductivities. The strong phonon scatterings stem from the A-site mismatch and bond-length fluctuations induced by local distortions of MnO6 octahedra. The thermal conductivity in the magnetically ordered state is enhanced as a result of the decrease in spin–phonon scattering. The results also indicate that above the magnetic ordering temperature, observable thermal excitation of optical phonons occurs. The contribution of optical phonons to thermal conductivity becomes non-negligible and is proposed to play an important role in the glass-like thermal transport behavior (i.e. positive temperature dependence of the thermal conductivity) in the paramagnetic state. These features can be understood in terms of an expression of thermal conductivity that includes both acoustic and optical phonon terms. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410004969