Documents disponibles écrits par cet auteur

Bifurcation analysis of ultrashort self-acting gas journal bearings for MEMS / Zhou, Jian-Bin in IEEE transactions on industrial electronics, Vol. 56 N° 8 (Août 2009) 

Public ISBD [article]  in IEEE transactions on industrial electronics > Vol. 56 N° 8 (Août 2009) . - pp. 3188 - 3194 Titre : Bifurcation analysis of ultrashort self-acting gas journal bearings for MEMS Type de document : texte imprimé Auteurs : Zhou, Jian-Bin, Auteur ; Meng, Guang, Auteur ; Chen, Jie-Yu, Auteur Article en page(s) : pp. 3188 - 3194 Note générale : Génie électrique Langues : Anglais (eng) Mots-clés : Bifurcation  Gas  journal  bearing  Microelectromechanical  systems  (MEMS) Index. décimale : 621.38 Dispositifs électroniques. Tubes à électrons. Photocellules. Accélérateurs de particules. Tubes à rayons X Résumé : The development of microrotational devices in microelectromechanical systems (MEMS) has introduced a kind of ultrashort self-acting gas journal bearing with low length-to-diameter ratios. The bifurcation of ultrashort self-acting gas journal bearing-rotor systems is studied in this paper. The system is modeled as a rigid rotor supported by bearing forces as a result of gas viscosity and rotational speed. The spectral collection method is employed to discretize the nonlinear Reynolds equation describing the pressure distribution of the working fluid of the bearing. A system of nonlinear partial differential equations, which couples the fluid equation and the equations of the rotor motion, is presented and solved using the Runge-Kutta method. The bifurcation diagram, rotor center orbits, phase portraits, frequency spectra, and Poincare maps are utilized to analyze the dynamic characteristics of the rotor-bearing system for different operating conditions. The effects of the rotational speed and length-to-diameter ratio on the system dynamic behaviors are investigated with both low and high initial eccentricity ratios. The analyses show that the system exhibits complicated behaviors at low eccentricity ratios as a result of the self-excited whirl motion. For high eccentricity ratios, the bearing behavior comprises synchronous and subharmonic motions. A further understanding of the nonlinear dynamics of gas journal bearing in MEMS is given by the analysis results. DEWEY : 621.38 ISSN : 0278-0046 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4914873 [article] Bifurcation analysis of ultrashort self-acting gas journal bearings for MEMS [texte imprimé] / Zhou, Jian-Bin, Auteur ; Meng, Guang, Auteur ; Chen, Jie-Yu, Auteur . - pp. 3188 - 3194. Génie électrique Langues : Anglais (eng) in IEEE transactions on industrial electronics > Vol. 56 N° 8 (Août 2009) . - pp. 3188 - 3194 Mots-clés : Bifurcation  Gas  journal  bearing  Microelectromechanical  systems  (MEMS) Index. décimale : 621.38 Dispositifs électroniques. Tubes à électrons. Photocellules. Accélérateurs de particules. Tubes à rayons X Résumé : The development of microrotational devices in microelectromechanical systems (MEMS) has introduced a kind of ultrashort self-acting gas journal bearing with low length-to-diameter ratios. The bifurcation of ultrashort self-acting gas journal bearing-rotor systems is studied in this paper. The system is modeled as a rigid rotor supported by bearing forces as a result of gas viscosity and rotational speed. The spectral collection method is employed to discretize the nonlinear Reynolds equation describing the pressure distribution of the working fluid of the bearing. A system of nonlinear partial differential equations, which couples the fluid equation and the equations of the rotor motion, is presented and solved using the Runge-Kutta method. The bifurcation diagram, rotor center orbits, phase portraits, frequency spectra, and Poincare maps are utilized to analyze the dynamic characteristics of the rotor-bearing system for different operating conditions. The effects of the rotational speed and length-to-diameter ratio on the system dynamic behaviors are investigated with both low and high initial eccentricity ratios. The analyses show that the system exhibits complicated behaviors at low eccentricity ratios as a result of the self-excited whirl motion. For high eccentricity ratios, the bearing behavior comprises synchronous and subharmonic motions. A further understanding of the nonlinear dynamics of gas journal bearing in MEMS is given by the analysis results. DEWEY : 621.38 ISSN : 0278-0046 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4914873

Coupled nonlinear effects of random surface roughness and rarefaction on slip flow in ultra-thin film gas bearing lubrication / Wen-Ming Zhang in Transactions of the ASME . Journal of tribology, Vol. 134 N° 2 (Avril 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 134 N° 2 (Avril 2012) . - 08 p. Titre : Coupled nonlinear effects of random surface roughness and rarefaction on slip flow in ultra-thin film gas bearing lubrication Type de document : texte imprimé Auteurs : Wen-Ming Zhang, Auteur ; Meng, Guang, Auteur ; Zhi-Ke Peng, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : tribology Langues : Anglais (eng) Mots-clés : gas  bearing  lubrication;  slip  flow;  rarefaction;  random  rough  surface Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A mathematical model of gaseous slip flow in ultra-thin film gas bearings is numerically analyzed incorporating effects of surface roughness, which is characterized by fractal geometry. The Weierstrass-Mandelbrot (W-M) function is presented to represent the multiscale self-affine roughness of the surface. A modified Reynolds equation incorporating velocity slip boundary condition is applied for the arbitrary range of Knudsen numbers in the slip and transition regimes. The effects of bearing number, Knudsen number, geometry parameters of the bearing and roughness parameters on the complex flow behaviors of the gas bearing are investigated and discussed. Numerical solutions are obtained for various bearing configurations under the coupled effects of rarefaction and roughness. The results indicate that roughness has a more significant effect on higher Knudsen number (rarefaction effect) flows with higher relative roughness. Surface with larger fractal dimensions yield more frequency variations in the surface profile, which result in an obviously larger incremental pressure loss. The Poiseuille number increases not only with increasing of rarefaction effect but also with increasing the surface roughness. It can also be observed that the current study is in good agreement with solutions obtained from the linearized Boltzmann equation. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE9000134000002 [...] [article] Coupled nonlinear effects of random surface roughness and rarefaction on slip flow in ultra-thin film gas bearing lubrication [texte imprimé] / Wen-Ming Zhang, Auteur ; Meng, Guang, Auteur ; Zhi-Ke Peng, Auteur . - 2012 . - 08 p. tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 134 N° 2 (Avril 2012) . - 08 p. Mots-clés : gas  bearing  lubrication;  slip  flow;  rarefaction;  random  rough  surface Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A mathematical model of gaseous slip flow in ultra-thin film gas bearings is numerically analyzed incorporating effects of surface roughness, which is characterized by fractal geometry. The Weierstrass-Mandelbrot (W-M) function is presented to represent the multiscale self-affine roughness of the surface. A modified Reynolds equation incorporating velocity slip boundary condition is applied for the arbitrary range of Knudsen numbers in the slip and transition regimes. The effects of bearing number, Knudsen number, geometry parameters of the bearing and roughness parameters on the complex flow behaviors of the gas bearing are investigated and discussed. Numerical solutions are obtained for various bearing configurations under the coupled effects of rarefaction and roughness. The results indicate that roughness has a more significant effect on higher Knudsen number (rarefaction effect) flows with higher relative roughness. Surface with larger fractal dimensions yield more frequency variations in the surface profile, which result in an obviously larger incremental pressure loss. The Poiseuille number increases not only with increasing of rarefaction effect but also with increasing the surface roughness. It can also be observed that the current study is in good agreement with solutions obtained from the linearized Boltzmann equation. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE9000134000002 [...]

Stochastic Response of a Random Mass Structure / Leng, Xiaolei in Journal of engineering mechanics, vol.131, N° 7 (juillet 2005)

Public ISBD [article]  in Journal of engineering mechanics > vol.131, N° 7 (juillet 2005) . - 747-751 p. Titre : Stochastic Response of a Random Mass Structure Titre original : Réponse Stochastique d'une Structure de Masse Aléatoire Type de document : texte imprimé Auteurs : Leng, Xiaolei, Auteur ; Fang, Tong, Auteur ; Meng, Guang ; Zhang, Tao Article en page(s) : 747-751 p. Note générale : Génie Civil, Génie Mécanique Langues : Anglais (eng) Mots-clés : Dynamic  structural  analysis  Stochastic  processes  Polynomials  Analyse  structurale  dynamique  Processus  stochastique  Polynômes Index. décimale : 624/621.34 Résumé : This Paper proposes a polynomial approximation approach for the estimation of the stochastic response of a random mass structure subjected to an evolutionary random excitation. A Bouded, monopeak, and symmetrically distributed probability density function, called (λ-PDF), together with the Gegenbauer polynomial approximation, is introduced to deal with stochastic dynamic response problems of the random mass structures. The (λ-PDF) model is used to describe the random parameters in the engineering random structures. And then the Gegenbauer polynomial approximation method is used to reduce the random structures into its deterministic equivalent one. The Numerrical example shows the effectiveness of the proposed method to explore dynamic phenomena in random structures. Cet article propose une approche polynôme d'approximation pour l'évaluation de la réponse stochastique d'une structure de masse aléatoire soumise à une excitation aléatoire évolutionnaire. Un Bouded, monopeak, et la fonction symétriquement distribuée de densité de probabilité, ont appelé (λ-PDF), ainsi que l'approximation polynôme de Gegenbauer, est présenté pour traiter des problèmes stochastiques de réponse dynamique des structures de masse aléatoires. Le modèle (λ-PDF) est employé pour décrire les paramètres aléatoires dans les structures aléatoires de technologie. Et alors la méthode polynôme d'approximation de Gegenbauer est employée pour réduire les structures aléatoires dans son équivalent déterministe un. L'exemple de Numerrical montre que l'efficacité de la méthode proposée explorait des phénomènes dynamiques en structures aléatoires. [article] Stochastic Response of a Random Mass Structure = Réponse Stochastique d'une Structure de Masse Aléatoire [texte imprimé] / Leng, Xiaolei, Auteur ; Fang, Tong, Auteur ; Meng, Guang ; Zhang, Tao . - 747-751 p. Génie Civil, Génie Mécanique Langues : Anglais (eng) in Journal of engineering mechanics > vol.131, N° 7 (juillet 2005) . - 747-751 p. Mots-clés : Dynamic  structural  analysis  Stochastic  processes  Polynomials  Analyse  structurale  dynamique  Processus  stochastique  Polynômes Index. décimale : 624/621.34 Résumé : This Paper proposes a polynomial approximation approach for the estimation of the stochastic response of a random mass structure subjected to an evolutionary random excitation. A Bouded, monopeak, and symmetrically distributed probability density function, called (λ-PDF), together with the Gegenbauer polynomial approximation, is introduced to deal with stochastic dynamic response problems of the random mass structures. The (λ-PDF) model is used to describe the random parameters in the engineering random structures. And then the Gegenbauer polynomial approximation method is used to reduce the random structures into its deterministic equivalent one. The Numerrical example shows the effectiveness of the proposed method to explore dynamic phenomena in random structures. Cet article propose une approche polynôme d'approximation pour l'évaluation de la réponse stochastique d'une structure de masse aléatoire soumise à une excitation aléatoire évolutionnaire. Un Bouded, monopeak, et la fonction symétriquement distribuée de densité de probabilité, ont appelé (λ-PDF), ainsi que l'approximation polynôme de Gegenbauer, est présenté pour traiter des problèmes stochastiques de réponse dynamique des structures de masse aléatoires. Le modèle (λ-PDF) est employé pour décrire les paramètres aléatoires dans les structures aléatoires de technologie. Et alors la méthode polynôme d'approximation de Gegenbauer est employée pour réduire les structures aléatoires dans son équivalent déterministe un. L'exemple de Numerrical montre que l'efficacité de la méthode proposée explorait des phénomènes dynamiques en structures aléatoires.