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Search Results: 1 - 10 of 101801 matches for " Jianwei Zhang "
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Preparation of KOH/CaO/C Supported Biodiesel Catalyst and Application Process  [PDF]
Jianwei Zhang, Qingming Meng
World Journal of Engineering and Technology (WJET) , 2014, DOI: 10.4236/wjet.2014.23020
Abstract: KOH/CaO/C supported catalyst was prepared via incipient wetness impregnation and used in synthesis of biodiesel. First, the effects of carrier/active components mass ratio, calcination temperature and calcination time on catalytic activity were investigated aiming at biodiesel yield, and the optimal process conditions for preparation of KOH/CaO/C catalysts were: mass ratio of C/CaO was 4:6; KOH solution (mass concentration) was 25%; impregnation time was 24 h; drying temperature was 105°C and time was 4 h; calcination temperature was 500°C and time was 5 h. Then the complex catalysts prepared under the optimal conditions were applied to synthesize biodiesel, and the effects of dose of catalyst, reaction temperature, and reaction time on the yield of biodiesel were investigated. At last, the optimal process conditions for synthesis of biodiesel were concluded: methanol-oil ratio was 10:1; catalyst dose was 2% of that of soybean oil; reaction temperature was 65°C; reaction time was 5 h. The yield of as-prepared biodiesel could be 98%.
Intrinsic Kinetics of Hydrorefining Catalyst in Ex-Situ Presulfurization  [PDF]
Jianwei Zhang, Jian Wang, Kai Wu
World Journal of Engineering and Technology (WJET) , 2014, DOI: 10.4236/wjet.2014.22012
Abstract: The intrinsic kinetics of hydrorefining catalyst in ex-situ presulfurization was investigated using a fixed-bed penetrating method. A mathematical model was built to express the intrinsic kinetics of presulfurization using an unreacted shrinking core model for catalyst grains and one-dimension unhomogeneous model for beds, and then the significance of the new model was tested. Results show that the presulfurization with hydrorefining catalyst was a nonstationary process, as the reaction rate changed with time, and this first-order reaction displayed high activation energy. In this dynamic mathematical model, a correction coefficient f0 was introduced into the common power-function-formed rate equation, which indicated the effects of solid diffusion on reaction. The model with high significance was able to improve the presulfurization rate and the raw material utilization ratio, thus providing theoretical guidance for achieving high presulfurization effects.

Estimate on Performance Evaluation of China’s Central Enterprise Listed Company Based on the EVA  [PDF]
Si Zhang, Jianwei Deng, Wei Du
American Journal of Industrial and Business Management (AJIBM) , 2014, DOI: 10.4236/ajibm.2014.48048
Abstract:

Since China joined the WTO, the enterprises, especially central enterprises, have actively participated in the international competition. Assessing the results of the operations and the asset utilization has become a top priority. To provide new investment ideas for investors, this paper introduces the EVA to assess the results of operation.

Organizational Climate and its Effects on Organizational Variables: An Empirical Study
Jianwei Zhang,Yuxin Liu
International Journal of Psychological Studies , 2010, DOI: 10.5539/ijps.v2n2p189
Abstract: This study investigated the characteristics of organizational climate and its effects on organizational variables. Investigation of 419 participants including both managers and employees indicated as follows: educational level, position and length of time working for the current organization had significant main effects on organizational climate; specialty, enterprise character and enterprise size also had significant main effects on organizational climate; organizational climate had significant main effects on human resources management effectiveness such as turnover intention, job satisfaction and work efficacy; organizational climate also had significant main effects on organization effectiveness like staff members’ organization commitment and collective identity.
Strong nuclear enhancement in intermediate mass Drell-Yan production
Jianwei Qiu,Xiaofei Zhang
Physics , 2001, DOI: 10.1016/S0370-2693(01)01446-0
Abstract: We calculate nuclear effect in Drell-Yan massive lepton-pair production in terms of parton multiple scattering in Quantum Chromodynamics (QCD). We present the nuclear modification to inclusive Drell-Yan cross section $d\sigma/dQ^2$ in terms of multiparton correlation functions. By extracting the size of the correlation functions from measured Drell-Yan transverse momentum broadening in nuclear medium, we determine the nuclear modification at $O(\alpha_s/Q^2)$. We find that the nuclear modification strongly enhances the inclusive Drell-Yan cross section in the intermediate mass region (IMR): $1.5 < Q < 2.5$ GeV. We argue that the Drell-Yan process is responsible for the majority of the observed dimuon enhancement in the IMR in the Pb-Pb collisions at CERN SPS.
Role of the nonperturbative input in QCD resummed Drell-Yan $Q_T$-distributions
Jianwei Qiu,Xiaofei Zhang
Physics , 2000, DOI: 10.1103/PhysRevD.63.114011
Abstract: We analyze the role of the nonperturbative input in the Collins, Soper, and Sterman (CSS)'s $b$-space QCD resummation formalism for Drell-Yan transverse momentum ($Q_T$) distributions, and investigate the predictive power of the CSS formalism. We find that the predictive power of the CSS formalism has a strong dependence on the collision energy $\sqrt{S}$ in addition to its well-known $Q^2$ dependence, and the $\sqrt{S}$ dependence improves the predictive power at collider energies. We show that a reliable extrapolation from perturbatively resummed $b$-space distributions to the nonperturbative large $b$ region is necessary to ensure the correct $Q_T$ distributions. By adding power corrections to the renormalization group equations in the CSS formalism, we derive a new extrapolation formalism. We demonstrate that at collider energies, the CSS resummation formalism plus our extrapolation has an excellent predictive power for $W$ and $Z$ production at all transverse momenta $Q_T\le Q$. We also show that the $b$-space resummed $Q_T$ distributions provide a good description of Drell-Yan data at fixed target energies.
Virtual photon fragmentation functions
Jianwei Qiu,Xiaofei Zhang
Physics , 2000, DOI: 10.1103/PhysRevD.64.074007
Abstract: We introduce operator definitions for virtual photon fragmentation functions, which are needed for reliable calculations of Drell-Yan transverse momentum ($Q_T$) distributions when $Q_T$ is much larger than the invariant mass $Q$. We derive the evolution equations for these fragmentation functions. We calculate the leading order evolution kernels for partons to fragment into a unpolarized as well as a polarized virtual photon. We find that fragmentation functions to a longitudinally polarized virtual photon are most important at small $z$, and the fragmentation functions to a transversely polarized virtual photon dominate the large $z$ region. We discuss the implications of this finding to the J/$\psi$ mesons' polarization at large transverse momentum.
QCD prediction for heavy boson transverse momentum distributions
Jianwei Qiu,Xiaofei Zhang
Physics , 2000, DOI: 10.1103/PhysRevLett.86.2724
Abstract: We investigate the predictive power of Collins, Soper, and Sterman's $b$-space QCD resummation formalism for transverse momentum ($Q_T$) distributions of heavy boson production in hadronic collisions. We show that the predictive power of the resummation formalism has a strong dependence on the collision energy $\sqrt{S}$ in addition to its well-known $Q^2$ dependence, and the $\sqrt{S}$ dependence improves the predictive power at collider energies. We demonstrate that at Tevatron and the LHC energies, the $Q_T$ distributions derived from $b$-space resummation are not sensitive to the nonperturbative input at large $b$, and give good descriptions of the $Q_T$ distributions of heavy boson production at all transverse momenta $Q_T \leq Q$.
Molecular Dynamic Simulation Study on Glass Transition Temperature of DGEBA-THPA/SWCNTs Composites  [PDF]
Cai Jiang, Jianwei Zhang, Shaofeng Lin, Dazhi Jiang
Journal of Materials Science and Chemical Engineering (MSCE) , 2014, DOI: 10.4236/msce.2014.21005
Abstract:

Molecular dynamic (MD) simulations were carried out to predict the thermo-mechanical properties of the cured epoxy network composed of diglycidyl ether bisphenol A (DGEBA) epoxy resin and tetrahydrophthalic anhydride (THPA) curing agent and their single-walled carbon nanotubes (SWCNT) reinforced the epoxy matrix composites. Different characters such as the density of the materials and mean square displacements (MSDs) were calculated to estimate the glass transition temperatures (Tgs) of of the materials. 365 K and 423 K of the Tgs were obtained respectively, whereas the latter is much higher than the former. The simulation results indicated that the incorporation of SWCNTs in the epoxy matrix can significantly improve the Tg of the cured epoxy. The approach presented in this study is ready to be applied more widely to a large group of candidate polymers and nanofillers.

Different steady states for spin currents in noncollinear multilayers
Peter M Levy,Jianwei Zhang
Physics , 2004, DOI: 10.1088/0953-8984/16/48/016
Abstract: We find there are at least two different steady states for transport across noncollinear magnetic multilayers. In the conventional one there is a discontinuity in the spin current across the interfaces which has been identified as the source of current induced magnetic reversal; in the one advocated herein the spin torque arises from the spin accumulation transverse to the magnetization of a magnetic layer. These two states have quite different attributes which should be discerned by current experiments.
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