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THE LIGHT INDUCED CHANGE IN TRANSIENT PHOTOCONDUC-TIVITy OF POLyMORPHOUS SILICON FILMS

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Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 453-456页

作者： S.B. Zhang, G.L. Kong, y. y. Xu, y.q. wang, H.W. Diao and X.B. Liao (State Laboratory for Surface Physics, Institute of Semiconductors & Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100083, China) State Laboratory for Surface Physics Institute of Semiconductors & Center for Condensed Matter Physics.Chinese Academy of Sciences Beijing 100083 China

The decays of transient photoconductivity and their light-induced changes of polymorphous silicon (pm-Si:H) films were investigated. The decays can be fit fairly well by a sum of two exponential decay functions, which indicates that there are two kinds of traps contributing to the process. The light-induced changes of the concentration and energy level of the traps were estimated. The results show that the light-induced changes in trap energy position Et, trap concentration Nt as well as photoconductivity are markedly less for pm-Si:H than that for a-Si:H.

关键词： light-induced change transient film

Long-Term Variations, Signatures, Sources of Asian Dust and Role of Climate Change Versus Desertification in Asian Dust Emission

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过程工程学报 2004年第Z1期4卷 699-699页

作者： X.y. Zhang S.L. Gong T.L. Zhao R. Arimoto y.q. wang Z.J. Zhou Institute of Earth Environment Chinese Acad. of Sciences China Institute of Earth Environment Chinese Acad. of Sciences China AqRB Meteorological Service of Canada Canada AqRB Meteorological Service of Canada Canada CEMRC New Mexico State Univ. USA

　　For long-term variations and elemental signatures of Asian dust aerosol, changes in mass, twenty elemental concentrations over the period 2001～2003 were assessed from five surface-based stations in western, northern, northeast deserts, the Loess Plateau and the coastal areas in China. Together with the back trajectory analyses and visibility observations, the elemental signatures of soil dust aerosol from different air-mass clusters were characterized for the dust storm (DS) and non-dust storm (N-DS)conditions, respectively.……

关键词： Asian Dust dust aerosol dust storm Loess Plateau coastal areas

An analysis of the chaotic motion of particles of different sizes in a gas fluidized bed

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Particuology 2008年第6期6卷 549-556页

作者： y.q. Feng A.B. yu Lab for Simulation and Modelling of Particulate Systems School of Materials Science and Engineering University of New South Wales Sydney NSW 2052 Australia

The dynamic behavior of individual particles during the mixing/segregation process of particle mixtures in a gas fluidized bed is analyzed. The analysis is based on the results generated from discrete particle simulation, with the focus on the trajectory of and forces acting on individual particles. Typical particles are selected representing three kinds of particle motion： a flotsam particle which is initially at the bottom part of the bed and finally fluidized at the top part of the bed; a jetsam particle which is initially at the top part of the bed and finally stays in the bottom de-fluidized layer of the bed; and a jetsam particle which is intermittently joining the top fluidized and bottom de-fluidized layers. The results show that the motion of a particle is chaotic at macroscopic or global scale, but can be well explained at a microscopic scale in terms of its interaction forces and contact conditions with other particles, particle-fluid interaction force, and local flow structure. They also highlight the need for establishing a suitable method to link the information generated and modeled at different time and length scales.

关键词： Fluidization Segregation Discrete particle simulation Granular dynamics

Numerical Simulation of Electroosmotic Flow near Earthworm Surface

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Journal of Bionic Engineering 2006年第4期3卷 179-186页

作者： y.q. Zu y.y. yan School of the Built Environment The University of Nottingham Nottingham NG7 2RD UK

The electroosmotic flow near an earthworm surface is simulated numerically to further understand the anti soil adhesion mechanism of earthworm. A lattice Poisson method is employed to solve electric potential and charge .distributiorts in the electric double layer along the earthworm surface. The external electric field is obtained by solving a Laplace equation. The electroosmotic flow controlled by the Navier-Stokes equations with external body force is simulated by the lattice Boltzmann method. A benchmark test shows that accurate electric potential distributions can be obtained by the LPM. The simulation shows that the moving vortices, which probably contribute to anti soil adhesion, are formed near earthworm body surface by the nonuniform and variational electrical force.

关键词： electroosmotic flow earthworm anti-adhesion LBM EDL

Synthesis and Room Temperature Ferromagnetism of Flower-shaped Mn Doped ZnO Nanostructures

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Journal of Materials Science & Technology 2011年第6期27卷 513-517页

作者： y.q. Chang P.W. wang R.H. Tang q.L. Sun y. Long School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Physics National Key Laboratory of Mesoscopic Physics Peking University Beijing 100871 China

Large-scale flower-shaped Mn doped ZnO nanostructures have been grown on silicon substrates by simple thermal evaporation at atmospheric *** flower-shaped nanostructure makes up of many nanorods,which are rooted in one *** of X-ray diffraction,high-resolution transmission electron microscopy and Raman spectra results reveal that the products are of single phase with wurtzite *** mapping results show that no impurity clusters exist in the doped *** photoluminescence spectra demonstrate that many oxygen vacancies exist in the doped materials,and the crystal quality is improved and the content of oxygen vacancies is decreased by annealing *** flower-shaped Mn doped ZnO nanostructures exhibit ferromagnetic ordering above room temperature,and its magnetization is decreased by the annealing treatment,which indicates that the magnetic behavior of the doped materials may be related to the interaction between Mn doping and the oxygen vacancies.

关键词： Mn doped ZnO nanomaterials Ferromagnetism Annealing treatment Chemical vapor deposition

ATOMIC STATES AND BRITTLENESS OF hcp Ti_3Al-ORDERED-TyPE ALLOyS

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Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 270-276页

作者： H.J. Peng y.q. Xie College of Chemistry and Chemical Engineering Central South University Changsha 410083 China College of Materials Science and Engineering Central South University Changsha 410083 China

On the basis of the framework of systematic science of alloys （SSA）, the basic information such as states, volumes, and potential energies of characteristic atoms in hcp Ti-Al system have been determined. The average atomic state of the hcp Ti3Al compound consisting of ψ4^Ti and ψ0^Al atoms is 0.75[Ar] （3dn）^0.573 （3dc）^2.1685 （4sc）^0.972 （4sf）^0.3093 ＋ 0.25[Ne] （3sc）^1.32 （3pc）^1.19 （3sf ＋ 3pf）^0.49. The brittleness of the ordered hcp Ti3Al compound has been discussed considering the fundamental factors, which are atomic states, bond networks, potential energy wave planes, and the ratio xTi/xAl. The existence of more pc and more dc directional electrons in the hcp Ti3Al compound lead to considerable brittleness; From bond networks and potential energy wave planes, the hcp Ti3Al compound has poorer ductility than the pure hcp Ti metal and the pure fcc Al metal; The Al-rich hcp Ti3Al ordered type alloys have poorer ductility than the Ti-rich hcp Ti3Al ordered type alloys.

关键词： Ti3Al alloy atomic state brittleness

Influence of Co Content on Raman and Photoluminescence Spectra of Co Doped ZnO Nanowires

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Journal of Materials Science & Technology 2012年第4期28卷 313-316页

作者： y.q. Chang P.W. wang S.L. Ni y. Long X.D. Li School of Materials Science anti Engineering University of Science and Technology Beijing Beijing 100083 China Department of Physics National Key Laboratory of Mesoscopic Physics Peking University Beijing 100871 China

Co doped ZnO nanowires with different Co contents have been fabricated by a chemical vapor deposition method. X-ray diffraction results show that all the samples are of single phase and crystallize in wurtzite ZnO structure. The lattice parameter a increases with increasing Co content, while the parameter c has no obvious change with increasing Co. Raman spectra show that the nonpolar E2（High） mode becomes broad and weak with the doping of Co, which indicates that the incorporation of Co causes structural disorder in the crystalline columnar ZnO lattice. The photolurninescence spectra exhibit that the position of the ultraviolet emission shifts to short wavelength and the intensity decreases with increasing Co. The green emission is affected by two contrary factors. It is increased by the introduced defects, but suppressed by the interaction between Co doping and native defects and the later affects it more significantly.

关键词： Co doped ZnO nanowires Raman Photoluminescence Single phase

EFFECT OF STRUCTURAL PARAMETERS ON THE THERMAL STRESS OF A NiFe_(2)O_(4)-BASED CERMET INERT ANODE IN ALUMINUM ELECTROLySIS

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Acta Metallurgica Sinica(English Letters) 2007年第2期20卷 139-147页

作者： J. Li Z.G. wang y.q. Lai y.y. Wu S.L. ye School of Metallurgy Science and Engineering Central South University Changsha 410083 China

Inert anode has been a hot issue in the aluminum industry for many decades. With the help of FEA （finite element analysis） software ANSyS, a model was developed to simulate the thermal stress distribution working condition of an inert anode. To reduce its thermal stress, the effect of some parameters on the thermal stress distribution was investigated, including the anode height, the anode radius, the hole depth, the hole radius, and the radius of inner chamfer and outer chamfer. The results showed that in the actual working condition of an inert anode, there existed a large axial tensile stress near the tangent interface between the anode and bath, which was the major cause of anode breaking. Increasing the anode height and reducing the hole depth properly seemed to be beneficial for the stress distribution. With the increase of anode radius, the stress distribution became better first and then deteriorated, the reasonable value was between 0.045 to 0.06m. The hole radius had a significant effect on the stress and a smaller radius would reduce the thermal stress. The effect of the radius of the inner chamfer and the outer chamfer was less than other parameters.

关键词： inert anode thermal stress structural parameter aluminum electrolysis

COUPLED SIMULATION OF 3D ELECTRO-MAGNETO-FLOW FIELD IN HALL-HEROULT CELLS USING FINITE ELEMENT METHOD

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Acta Metallurgica Sinica(English Letters) 2006年第2期19卷 105-116页

作者： J. Li W. Liu y.q. Lai q.y. Li y.X. Liu School of Metallurgy Science and Engineering Central South University Changsha 410083 China Chemistry Department Guangxi Normal University Guilin 531400 China

Two full 3D steady mathematical models are developed by finite element method （FEM） to calcalate coupled physics fields. the electro-magnetic model is built and solved first and so is the fluid motion model with the acquired electromagnetic force as source body forces in Navier-Stokes equations. Effects caused by the ferromagnetic shell, busbar system around, and open boundary problem as well as inside induced current were considered in terms of the magnetic field. Furthermore, a new modeling method is found to set up solid models and then mesh them entirely with so-called structuralized grids, namely hex-mesh. Examples of 75kA prebaked cell with two kinds of busbar arrangements are presented. Results agree with those disclosed in the literature and confirm that the coupled simulation is valid. It is also concluded that the usage of these models facilitates the consistent analysis of the electric field to magnetic field and then flow motion to the greater extent, local distributions of current density and magnetic flux density are very much dependent on the cell structure, the steel shell is a shield to reduce the magnetic field and flow pattern is two dimensional in the main body of the metal pad.

关键词： coupled simulation electromagnetic field flow field aluminum reduction cell finite element analysis