Documents disponibles écrits par cet auteur

Calculation of moisture distribution in early-age concrete / Zhang, Jun in Journal of engineering mechanics, Vol. 135 N° 8 (Août 2009) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 135 N° 8 (Août 2009) . - pp. 871-880 Titre : Calculation of moisture distribution in early-age concrete Type de document : texte imprimé Auteurs : Zhang, Jun, Auteur ; Qi, Kun, Auteur ; Huang, Yu, Auteur Article en page(s) : pp. 871-880 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Concrete  Aging  Moisture  Humidity. Résumé : The moisture content in concrete pores is a critical parameter for most of the degradation processes suffered by concrete, such as concrete shrinkage and related cracking. The objective of this paper is to present the formulation of a general moisture distribution model for young-age concrete. In the modeling, both cement hydration and moisture diffusion resulted humidity variations are taken into account synchronously. The effect of initial water distribution (after concrete casting) on the development of moisture distribution is considered by introducing a critical time parameter. The simulation of humidity reduction produced from self-desiccation is based on cement hydration degree that taking the effect of temperature into account by using the equilibrant age concept. During modeling the moisture diffusion, a multilinear model was adopted to simulate the moisture dependent diffusivity. The developed model and finite deferential method can well predict the moisture distribution as well as its variations with time. Good agreement between model predictions and experimental results is found. These results can subsequently be used in shrinkage induced stress field analyses, and further be used for cracking control of concrete structures. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&smode=strres [...] [article] Calculation of moisture distribution in early-age concrete [texte imprimé] / Zhang, Jun, Auteur ; Qi, Kun, Auteur ; Huang, Yu, Auteur . - pp. 871-880. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 135 N° 8 (Août 2009) . - pp. 871-880 Mots-clés : Concrete  Aging  Moisture  Humidity. Résumé : The moisture content in concrete pores is a critical parameter for most of the degradation processes suffered by concrete, such as concrete shrinkage and related cracking. The objective of this paper is to present the formulation of a general moisture distribution model for young-age concrete. In the modeling, both cement hydration and moisture diffusion resulted humidity variations are taken into account synchronously. The effect of initial water distribution (after concrete casting) on the development of moisture distribution is considered by introducing a critical time parameter. The simulation of humidity reduction produced from self-desiccation is based on cement hydration degree that taking the effect of temperature into account by using the equilibrant age concept. During modeling the moisture diffusion, a multilinear model was adopted to simulate the moisture dependent diffusivity. The developed model and finite deferential method can well predict the moisture distribution as well as its variations with time. Good agreement between model predictions and experimental results is found. These results can subsequently be used in shrinkage induced stress field analyses, and further be used for cracking control of concrete structures. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&smode=strres [...]

A direct-flux-vector-controlled induction generator with space-vector modulation for integrated starter alternator / Zhang, Jun in IEEE transactions on industrial electronics, Vol. 54 N°5 (Octobre 2007) 

Public ISBD [article]  in IEEE transactions on industrial electronics > Vol. 54 N°5 (Octobre 2007) . - 2512-2520 p. Titre : A direct-flux-vector-controlled induction generator with space-vector modulation for integrated starter alternator Type de document : texte imprimé Auteurs : Zhang, Jun, Auteur ; Muhammed Fazlur Rahman, Auteur Article en page(s) : 2512-2520 p. Note générale : Electronique Langues : Anglais (eng) Mots-clés : Direct-flux  vector  control  (DFC)  Induction  machine  Integrated  starter  alternator  (ISA)  Space-vector  modulation  (SVM)  42-V  PowerNet  Commande  de  vecteur  directe  de  flux  Machine  à  induction  Alternateur  intégré  de  démarreur  Modulation  de  vecteur  d'espace Index. décimale : 621 Ingénierie mécanique en général. Technologie nucléaire. Ingénierie électrique. Machinerie Résumé : A direct-flux-vector-controlled scheme of induction generator has been proposed in this paper for future 42-V automobile application. The fundamental relationship between the rotating speed of the stator flux vector and torque is analyzed. A simple structure with only one proportional-integral (PI) controller is shown to implement the torque and flux controls adequately. By controlling the electromagnetic torque of the induction machine, the required dc-bus voltage can be well regulated within the 42-V PowerNet specifications. Fixed switching frequency and low torque ripple are obtained with space-vector modulation technique. Simulation and experimental results indicate that the proposed scheme provides a practical solution for an integrated starter alternator other than the widely applied field-oriented- control scheme. On a proposé un arrangement diriger-flux-vecteur-commandé de générateur d'induction en ce document pour la future application de l'automobile 42-V. Le rapport fondamental entre la vitesse tournante du vecteur de flux de redresseur et le couple est analysé. Une structure simple avec seulement un contrôleur (pi) proportionnel-intégral est montrée pour mettre en application les commandes de couple et de flux en juste proportion. En commandant le couple électromagnétique de la machine d'induction, la tension exigée de C.C-autobus peut être bien réglée selon les caractéristiques de 42-V PowerNet. La fréquence fixe de commutation et la basse ondulation de couple sont obtenues avec la technique de modulation d'espace-vecteur. La simulation et les résultats expérimentaux indiquent que l'arrangement proposé fournit une solution pratique pour un alternateur intégré de démarreur autre que l'arrangement de commande champ-orienté largement appliqué. DEWEY : 621 ISSN : 0278-0046 RAMEAU : Analyse vectorielle-- Automobiles -- Alternateurs En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?isnumber=4282101&arnumber=4285716 [...] [article] A direct-flux-vector-controlled induction generator with space-vector modulation for integrated starter alternator [texte imprimé] / Zhang, Jun, Auteur ; Muhammed Fazlur Rahman, Auteur . - 2512-2520 p. Electronique Langues : Anglais (eng) in IEEE transactions on industrial electronics > Vol. 54 N°5 (Octobre 2007) . - 2512-2520 p. Mots-clés : Direct-flux  vector  control  (DFC)  Induction  machine  Integrated  starter  alternator  (ISA)  Space-vector  modulation  (SVM)  42-V  PowerNet  Commande  de  vecteur  directe  de  flux  Machine  à  induction  Alternateur  intégré  de  démarreur  Modulation  de  vecteur  d'espace Index. décimale : 621 Ingénierie mécanique en général. Technologie nucléaire. Ingénierie électrique. Machinerie Résumé : A direct-flux-vector-controlled scheme of induction generator has been proposed in this paper for future 42-V automobile application. The fundamental relationship between the rotating speed of the stator flux vector and torque is analyzed. A simple structure with only one proportional-integral (PI) controller is shown to implement the torque and flux controls adequately. By controlling the electromagnetic torque of the induction machine, the required dc-bus voltage can be well regulated within the 42-V PowerNet specifications. Fixed switching frequency and low torque ripple are obtained with space-vector modulation technique. Simulation and experimental results indicate that the proposed scheme provides a practical solution for an integrated starter alternator other than the widely applied field-oriented- control scheme. On a proposé un arrangement diriger-flux-vecteur-commandé de générateur d'induction en ce document pour la future application de l'automobile 42-V. Le rapport fondamental entre la vitesse tournante du vecteur de flux de redresseur et le couple est analysé. Une structure simple avec seulement un contrôleur (pi) proportionnel-intégral est montrée pour mettre en application les commandes de couple et de flux en juste proportion. En commandant le couple électromagnétique de la machine d'induction, la tension exigée de C.C-autobus peut être bien réglée selon les caractéristiques de 42-V PowerNet. La fréquence fixe de commutation et la basse ondulation de couple sont obtenues avec la technique de modulation d'espace-vecteur. La simulation et les résultats expérimentaux indiquent que l'arrangement proposé fournit une solution pratique pour un alternateur intégré de démarreur autre que l'arrangement de commande champ-orienté largement appliqué. DEWEY : 621 ISSN : 0278-0046 RAMEAU : Analyse vectorielle-- Automobiles -- Alternateurs En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?isnumber=4282101&arnumber=4285716 [...]

Engineered cementitious composite with characteristic of low drying shrinkage / Zhang, Jun in Cement and concrete research, Vol. 39 N° 4 (Avril 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 4 (Avril 2009) . - pp. 303–312 Titre : Engineered cementitious composite with characteristic of low drying shrinkage Type de document : texte imprimé Auteurs : Zhang, Jun, Auteur ; Chengxu Gong, Auteur ; Zili Guo, Auteur Année de publication : 2009 Article en page(s) : pp. 303–312 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Tensile  properties;  Shrinkage;  Composite;  Fiber  reinforcement Résumé : This paper reports a new class of engineered cementitious composite (ECC) with characteristics of low drying shrinkage, tight crack opening and high tensile strain capacity. Research emphasis is placed on the influence of different cementitious matrix on drying shrinkage, tensile property and early age cracking behavior of the composites. Experimental results show that drying shrinkage of the composite is greatly reduced as using the low shrinkage cementitious material in matrix, while the composite remains strain-hardening and multiple cracking characteristics. The measured drying shrinkage strain at 28 days is only 109 × 10− 6 to 242 × 10− 6 for low shrinkage ECCs. For traditional ECC, the shrinkage strain at 28 days is nearly 1200 × 10− 6. The average tensile strain capacity after 28 days curing is 2.5% of the low shrinkage ECC with tensile strength of 4–5 MPa. Further, in the strain-hardening and multiple cracking stage, cracks with much smaller width compared to the traditional ECC are formed in the low shrinkage ECC. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000398 [article] Engineered cementitious composite with characteristic of low drying shrinkage [texte imprimé] / Zhang, Jun, Auteur ; Chengxu Gong, Auteur ; Zili Guo, Auteur . - 2009 . - pp. 303–312. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 4 (Avril 2009) . - pp. 303–312 Mots-clés : Tensile  properties;  Shrinkage;  Composite;  Fiber  reinforcement Résumé : This paper reports a new class of engineered cementitious composite (ECC) with characteristics of low drying shrinkage, tight crack opening and high tensile strain capacity. Research emphasis is placed on the influence of different cementitious matrix on drying shrinkage, tensile property and early age cracking behavior of the composites. Experimental results show that drying shrinkage of the composite is greatly reduced as using the low shrinkage cementitious material in matrix, while the composite remains strain-hardening and multiple cracking characteristics. The measured drying shrinkage strain at 28 days is only 109 × 10− 6 to 242 × 10− 6 for low shrinkage ECCs. For traditional ECC, the shrinkage strain at 28 days is nearly 1200 × 10− 6. The average tensile strain capacity after 28 days curing is 2.5% of the low shrinkage ECC with tensile strength of 4–5 MPa. Further, in the strain-hardening and multiple cracking stage, cracks with much smaller width compared to the traditional ECC are formed in the low shrinkage ECC. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000398

Flyback-based single-stage power-factor-correction scheme with time-multiplexing control / Zhang, Jun in IEEE transactions on industrial electronics, Vol. 57 N° 3 (Mars 2010) 

Public ISBD [article]  in IEEE transactions on industrial electronics > Vol. 57 N° 3 (Mars 2010) . - pp. 1041 - 1049 Titre : Flyback-based single-stage power-factor-correction scheme with time-multiplexing control Type de document : texte imprimé Auteurs : Zhang, Jun, Auteur ; Lu, Dylan Dah-Chuan, Auteur ; Ting, Sun, Auteur Article en page(s) : pp. 1041 - 1049 Note générale : Génie électrique Langues : Anglais (eng) Mots-clés : AC-DC  converter  Power  factor  correction  (PFC)  Single  stage Index. décimale : 621.38 Dispositifs électroniques. Tubes à électrons. Photocellules. Accélérateurs de particules. Tubes à rayons X Résumé : A flyback-based single-stage power-factor-correction scheme with time-multiplexing control (TMC) is proposed. As a portion of the input power will be transferred to the output after the first power processing to improve the conversion efficiency, the output voltage would contain substantial low-frequency ripple. An isolated auxiliary circuit based on forward topology is therefore added to the converter to serve as a buffer and a ripple suppression circuit. With TMC, all the power processes can be achieved by a single transformer to lower the size and cost of the converter. In addition, the proposed converter inherits bulk capacitor (auxiliary) voltage clamping capability. The experimental results confirmed the effectiveness of the proposed scheme with high power factor, natural bulk capacitor (auxiliary) clamping voltage, and tight output regulation. DEWEY : 621.38 ISSN : 0278-0046 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5196760 [article] Flyback-based single-stage power-factor-correction scheme with time-multiplexing control [texte imprimé] / Zhang, Jun, Auteur ; Lu, Dylan Dah-Chuan, Auteur ; Ting, Sun, Auteur . - pp. 1041 - 1049. Génie électrique Langues : Anglais (eng) in IEEE transactions on industrial electronics > Vol. 57 N° 3 (Mars 2010) . - pp. 1041 - 1049 Mots-clés : AC-DC  converter  Power  factor  correction  (PFC)  Single  stage Index. décimale : 621.38 Dispositifs électroniques. Tubes à électrons. Photocellules. Accélérateurs de particules. Tubes à rayons X Résumé : A flyback-based single-stage power-factor-correction scheme with time-multiplexing control (TMC) is proposed. As a portion of the input power will be transferred to the output after the first power processing to improve the conversion efficiency, the output voltage would contain substantial low-frequency ripple. An isolated auxiliary circuit based on forward topology is therefore added to the converter to serve as a buffer and a ripple suppression circuit. With TMC, all the power processes can be achieved by a single transformer to lower the size and cost of the converter. In addition, the proposed converter inherits bulk capacitor (auxiliary) voltage clamping capability. The experimental results confirmed the effectiveness of the proposed scheme with high power factor, natural bulk capacitor (auxiliary) clamping voltage, and tight output regulation. DEWEY : 621.38 ISSN : 0278-0046 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5196760

A new feedback method for PR current control of LCL-filter-based grid-connected inverter / Guoqiao, Shen in IEEE transactions on industrial electronics, Vol. 57 N° 6 (Juin 2010) 

Public ISBD [article]  in IEEE transactions on industrial electronics > Vol. 57 N° 6 (Juin 2010) . - pp. 2033 - 2041 Titre : A new feedback method for PR current control of LCL-filter-based grid-connected inverter Type de document : texte imprimé Auteurs : Guoqiao, Shen, Auteur ; Xuancai, Zhu, Auteur ; Zhang, Jun, Auteur Article en page(s) : pp. 2033 - 2041 Note générale : Génie électrique Langues : Anglais (eng) Mots-clés : Current  control  Harmonic  distorsion  Inverters  LCL  filter Index. décimale : 621.38 Dispositifs électroniques. Tubes à électrons. Photocellules. Accélérateurs de particules. Tubes à rayons X Résumé : For a grid-connected converter with an LCL filter, the harmonic compensators of a proportional-resonant (PR) controller are usually limited to several low-order current harmonics due to system instability when the compensated frequency is out of the bandwidth of the system control loop. In this paper, a new current feedback method for PR current control is proposed. The weighted average value of the currents flowing through the two inductors of the LCL filter is used as the feedback to the current PR regulator. Consequently, the control system with the LCL filter is degraded from a third-order function to a first-order one. A large proportional control-loop gain can be chosen to obtain a wide control-loop bandwidth, and the system can be optimized easily for minimum current harmonic distortions, as well as system stability. The inverter system with the proposed controller is investigated and compared with those using traditional control methods. Experimental results on a 5-kW fuel-cell inverter are provided, and the new current control strategy has been verified. DEWEY : 621.38 ISSN : 0278-0046 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5406162 [article] A new feedback method for PR current control of LCL-filter-based grid-connected inverter [texte imprimé] / Guoqiao, Shen, Auteur ; Xuancai, Zhu, Auteur ; Zhang, Jun, Auteur . - pp. 2033 - 2041. Génie électrique Langues : Anglais (eng) in IEEE transactions on industrial electronics > Vol. 57 N° 6 (Juin 2010) . - pp. 2033 - 2041 Mots-clés : Current  control  Harmonic  distorsion  Inverters  LCL  filter Index. décimale : 621.38 Dispositifs électroniques. Tubes à électrons. Photocellules. Accélérateurs de particules. Tubes à rayons X Résumé : For a grid-connected converter with an LCL filter, the harmonic compensators of a proportional-resonant (PR) controller are usually limited to several low-order current harmonics due to system instability when the compensated frequency is out of the bandwidth of the system control loop. In this paper, a new current feedback method for PR current control is proposed. The weighted average value of the currents flowing through the two inductors of the LCL filter is used as the feedback to the current PR regulator. Consequently, the control system with the LCL filter is degraded from a third-order function to a first-order one. A large proportional control-loop gain can be chosen to obtain a wide control-loop bandwidth, and the system can be optimized easily for minimum current harmonic distortions, as well as system stability. The inverter system with the proposed controller is investigated and compared with those using traditional control methods. Experimental results on a 5-kW fuel-cell inverter are provided, and the new current control strategy has been verified. DEWEY : 621.38 ISSN : 0278-0046 En ligne : http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5406162

Photochemical oxidation removal of NO and SO2 from simulated flue gas of coal-fired power plants by wet scrubbing using UV/H2O2 advanced oxidation process / Yang xian Liu in Industrial & engineering chemistry research, Vol. 50 N° 7 (Avril 2011) 

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Study on mass transfer - reaction kinetics of NO removal from flue gas by using a UV / fenton - like reaction / Yangxian Liu in Industrial & engineering chemistry research, Vol. 51 N° 37 (Septembre 2012) 

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