Documents disponibles écrits par cet auteur

Compensation of VCM actuator pivot friction based on an operator modeling method / Chunling Du in IEEE Transactions on control systems technology, Vol. 18 N° 4 (Juillet 2010) 

Public ISBD [article]  in IEEE Transactions on control systems technology > Vol. 18 N° 4 (Juillet 2010) . - pp. 918-926 Titre : Compensation of VCM actuator pivot friction based on an operator modeling method Type de document : texte imprimé Auteurs : Chunling Du, Auteur ; Lihua Xie, Auteur ; Zhang, Jingliang, Auteur Année de publication : 2011 Article en page(s) : pp. 918-926 Note générale : Génie Aérospatial Langues : Anglais (eng) Mots-clés : Friction  modeling  and  compensation  Hard  disk  drives  (HDDs)  Hysteresis  Prandlt  operator  Sensitivity  function Index. décimale : 629.1 Résumé : The pivot friction of voice-coil-motor (VCM) actuator is measured for a 1.8-in small disk drive with disk rotating and slider flying. The measurement is carried out under the conditions that the actuator is controlled and the head movement amplitude is growing by changing the references. The hysteresis of friction versus head position is then obtained. An operator-based modeling approach is adopted for the hysteresis, and an optimal model is obtained by minimizing the energy gain between the head position and the modeling error. It is also found that the frequency response of the actuator model with the inclusion of the hyteresis model matches well with the measured frequency response of the actuator. A friction compensation method based on the nonlinear hysteresis model is thus proposed. The simulation and implementation results demonstrate a significant improvement in disturbance rejection at low frequencies. DEWEY : 629.1 ISSN : 1063-6536 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5238637 [article] Compensation of VCM actuator pivot friction based on an operator modeling method [texte imprimé] / Chunling Du, Auteur ; Lihua Xie, Auteur ; Zhang, Jingliang, Auteur . - 2011 . - pp. 918-926. Génie Aérospatial Langues : Anglais (eng) in IEEE Transactions on control systems technology > Vol. 18 N° 4 (Juillet 2010) . - pp. 918-926 Mots-clés : Friction  modeling  and  compensation  Hard  disk  drives  (HDDs)  Hysteresis  Prandlt  operator  Sensitivity  function Index. décimale : 629.1 Résumé : The pivot friction of voice-coil-motor (VCM) actuator is measured for a 1.8-in small disk drive with disk rotating and slider flying. The measurement is carried out under the conditions that the actuator is controlled and the head movement amplitude is growing by changing the references. The hysteresis of friction versus head position is then obtained. An operator-based modeling approach is adopted for the hysteresis, and an optimal model is obtained by minimizing the energy gain between the head position and the modeling error. It is also found that the frequency response of the actuator model with the inclusion of the hyteresis model matches well with the measured frequency response of the actuator. A friction compensation method based on the nonlinear hysteresis model is thus proposed. The simulation and implementation results demonstrate a significant improvement in disturbance rejection at low frequencies. DEWEY : 629.1 ISSN : 1063-6536 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5238637

Fault detection and isolation of nonlinear systems / Jun Xu in Transactions of the ASME . Journal of dynamic systems, measurement, and control, Vol. 134 N° 4 (Juillet 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 134 N° 4 (Juillet 2012) . - 07 p. Titre : Fault detection and isolation of nonlinear systems : an unknown input observer approach with sum-of-squares techniques Type de document : texte imprimé Auteurs : Jun Xu, Auteur ; Kai-Yew Lum, Auteur ; Lihua Xie, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Dynamic systems Langues : Anglais (eng) Mots-clés : Novel  nonlinear  unknown  input  observer  (UIO)  Fault  detection  and  isolation  (FDI)  Sum-of-squares  (SOS)  theory  Lie  geometry Index. décimale : 629.8 Résumé : This paper presents a novel nonlinear unknown input observer (UIO) design method for fault detection and isolation (FDI) of a class of nonlinear affine systems. By using sum-of-squares (SOS) theory and Lie geometry as the main tools, we demonstrate how to relax the rank constraint in the traditional UIO approach and simplify the design procedure, especially for the polynomial nonlinear systems. Meanwhile, we show that the detection and isolation thresholds based on the L2 gains can be easily obtained via optimization formulated in terms of SOS. Simulation examples are given to illustrate the design procedure and the advantages. DEWEY : 629.8 ISSN : 0022-0434 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JDSMAA000134000004 [...] [article] Fault detection and isolation of nonlinear systems : an unknown input observer approach with sum-of-squares techniques [texte imprimé] / Jun Xu, Auteur ; Kai-Yew Lum, Auteur ; Lihua Xie, Auteur . - 2012 . - 07 p. Dynamic systems Langues : Anglais (eng) in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 134 N° 4 (Juillet 2012) . - 07 p. Mots-clés : Novel  nonlinear  unknown  input  observer  (UIO)  Fault  detection  and  isolation  (FDI)  Sum-of-squares  (SOS)  theory  Lie  geometry Index. décimale : 629.8 Résumé : This paper presents a novel nonlinear unknown input observer (UIO) design method for fault detection and isolation (FDI) of a class of nonlinear affine systems. By using sum-of-squares (SOS) theory and Lie geometry as the main tools, we demonstrate how to relax the rank constraint in the traditional UIO approach and simplify the design procedure, especially for the polynomial nonlinear systems. Meanwhile, we show that the detection and isolation thresholds based on the L2 gains can be easily obtained via optimization formulated in terms of SOS. Simulation examples are given to illustrate the design procedure and the advantages. DEWEY : 629.8 ISSN : 0022-0434 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JDSMAA000134000004 [...]

New environment - friendly use of wheat straw in slow - release fertilizer formulations with the function of superabsorbent / Lihua Xie in Industrial & engineering chemistry research, Vol. 51 N° 10 (Mars 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 10 (Mars 2012) . - pp. 3855–3862 Titre : New environment - friendly use of wheat straw in slow - release fertilizer formulations with the function of superabsorbent Type de document : texte imprimé Auteurs : Lihua Xie, Auteur ; Mingzhu Liu, Auteur ; Boli Ni, Auteur Année de publication : 2012 Article en page(s) : pp. 3855–3862 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fertilizer  Superabsorbent Résumé : With the aim of improving fertilizer use efficiency and minimizing the negative impact on the environment, a new double-coated slow-release nitrogen and phosphorus fertilizer with water retention was prepared. Wheat straw was introduced into the formulations as the basic coating material. Specifically, poly(acrylic acid-co-N-hydroxymethyl acrylamide)/wheat straw superabsorbent composite was used as the outer coating, and wheat straw/sodium alginate blends was used as the inner coating. The degradation of the superabsorbent composite in the soil solution was studied. The impact of the content of wheat straw on the extent of degradation in cellulase solution was also examined. The superabsorbent composite synthesized under the optimal conditions showed super water absorbency and excellent degradability. The water-retention property and the nutrient slow-release behavior of the product were investigated. The results revealed that the product with water-retention and slow-release capacity, being economical, nontoxic in soil, and eco-friendly, could find good application in agriculture and horticulture. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2016043 [article] New environment - friendly use of wheat straw in slow - release fertilizer formulations with the function of superabsorbent [texte imprimé] / Lihua Xie, Auteur ; Mingzhu Liu, Auteur ; Boli Ni, Auteur . - 2012 . - pp. 3855–3862. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 10 (Mars 2012) . - pp. 3855–3862 Mots-clés : Fertilizer  Superabsorbent Résumé : With the aim of improving fertilizer use efficiency and minimizing the negative impact on the environment, a new double-coated slow-release nitrogen and phosphorus fertilizer with water retention was prepared. Wheat straw was introduced into the formulations as the basic coating material. Specifically, poly(acrylic acid-co-N-hydroxymethyl acrylamide)/wheat straw superabsorbent composite was used as the outer coating, and wheat straw/sodium alginate blends was used as the inner coating. The degradation of the superabsorbent composite in the soil solution was studied. The impact of the content of wheat straw on the extent of degradation in cellulase solution was also examined. The superabsorbent composite synthesized under the optimal conditions showed super water absorbency and excellent degradability. The water-retention property and the nutrient slow-release behavior of the product were investigated. The results revealed that the product with water-retention and slow-release capacity, being economical, nontoxic in soil, and eco-friendly, could find good application in agriculture and horticulture. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2016043