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Characteristics of fissures and pores of anthracite in Jincheng by SEM

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Mining Science and Technology 2010年第5期20卷 789-793页

作者： LI Guihong,ZHANG Hong,ZHANG Hui,SONG Xiaozhong Institute of Geology,Xi’an Branch,China Coal research Institute,Xi’an 710054,China Institute of Geology Xi'an Branch China Coal Research Institute Xi'an 710054 China

Anthracite in Jincheng is a highly metamorphic coal and its system of fissures and pores is differentfrom that of low and medium ranked *** order to discover their characteristics,69 samples were collected from 18 cbM wells in Zhengzhuang in Jincheng and their fissures and pores were observed by a Scanning Electron Microscope(SEM).To the naked eyes and by SEM,the pores in the Jincheng anthracite are seen to have abundant mold pores with isolated,shallow and poor connectivity(diameters between 1～50 μm) and few plant tissue pores,gas pores,and solution *** of the fissures are filled with clay minerals or closed;while open fissures are not often visible in the Jincheng coal(aperture between 3～10 μm).These characteristics are determined by the high rank and high vitrinite content of the *** existence of too many mold pores and filled fissures does not allow the migration of methane,hence hydraulic fracture stimulation will be required and is an effective method of adding and connecting fissures to enhance cbM production.

关键词： anthracite coalbed methane fissure pore

Microcrack analysis of Sanya grantite fragments from rockburst tests

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Mining Science and Technology 2010年第2期20卷 238-243页

作者： HE, Manchao NIE, Wen HAN, Liqiang LING, Lijing state key laboratory of geomechanics and deep underground engineering beijing 100083china school of mechanics & civil engineering china university of mining & technologybeijing 100083china school of mechanics & civil engineering china university of mining & technologybeijing 100083china

Fractures running along a plane reflect the cracking *** this paper uniaxial and rockburst tests on a group of granite specimens from Sanya province are *** electron microscopic imaging was used to characterize the *** fracture mechanics were used to analyze the microcracks in terms of both the crack type and the mineral constituent.A statistical analysis showed that the area of inter-granular cracking exceeds that of intra-granular *** types of crack were observed in the cracked *** percentage of intra-granular cracks in fragments from rockburst tests exceeds that from uniaxial compression *** results also showed that feldspar deformation was the main cause of fracture and that the consolidation along quartz grain boundaries was another weak area in the *** along quartz grains had enough energy to enter the quartz crystal in the rockburst *** these results contribute to further research on rockburst mechanics.

关键词： granite rockburst medium fragment quartz feldspar fractal analysis

Double-directional control bolt support technology and engineering application at large span Y-type intersections in deep coal mines

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Mining Science and Technology 2010年第2期20卷 254-259页

作者： GUO, Zhibiao SHI, Jianjun WANG, Jiong CAI, Feng WANG, Fuqiang state key laboratory of geomechanics and deep underground engineering beijing 100083china institute of geotechnical engineering china university of mining & technologybeijing 100083china safety engineering college north china university of science & technologybeijing 101601china

under deep and complex geological conditions,severe deformation occurs at intersection points of Y-type roadways with large cross sections during engineering projects in coal mines,especially at junction *** on in-situ investigations and theoretical studies,we have summarized typical forms of destruction and identified high stress and unrestricted support at both sides of junction arch as its main *** this study,we also presented double-directional control bolt support technology for a large Y-type span intersection,applied to deep intersection engineering in the Jiahe Coal Mine,which has proved effective.

关键词： Y-type intersection double-directional control bolt support deep coal mines

Initial Oxidation of γ-TiAl(111) Surface:Density-functional Theory Study

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Journal of Materials Science & Technology 2009年第4期25卷 569-576页

作者： Hong Li Shaoqing Wang Hengqiang Ye Shenyang national Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Graduate School of Chinese Academy of Sciences Beijing 100039 China Electron Microscope Lab Peking University Beijing 100871 China

In this paper, we reported a first-principles investigation on the structural and electronic properties of O adsorption on the γ-TiAI（111） surface, to illustrate the oxidation process. It has been found that：（1） rather than stopping with one full monolayer of coverage, oxygen adsorption continues till two monolayer coverage, rendering an oxide-like structure; （2） full structural relaxation makes the surface oxide layer denser and more stable, which hinders the subsequent O adsorption （oxidation） process. In addition, the transformation from metal to oxide surface was identified by analyzing the local density of states through the oxidation steps, which was in good agreement with experimental results.

关键词： Density-functional theory γ-TiAl Surface Oxidation

Central distance of interferential mode patterns of elliptical core two-mode fiber

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Chinese Optics Letters 2008年第9期6卷 640-643页

作者：王河林杨爱军 State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences College of Science Beijing Institute of Technology

By means of the weakly guiding approximation, the mode spot sizes Wx and Wy of the fundamental mode along the semimajor （x-direction） and semiminor （y-direction） axes of the fiber core in elliptical core two- mode fiber are discussed. The variation of their ratio value Wx/W9 with the operation wavelength A and the length ratio a/b between the semimajor axis and the semiminor axis of the fiber core is analyzed. Based on this analysis, the distribution figures of two-lobe interferential mode patterns are evaluated and simulated quantitatively for different phase difference changes between LP01 and LP~~n modes. The two-lobe interferential mode patterns have the same profile and distribute symmetrically when the phase difference equals ~r/2. Their central distance S becomes larger when W~：/W~ augments gradually. F^rthermore, the equation about the central distance S of the two-lobe interferential mode patterns is given when the operation wavelength varies between 0.65 and 1.31 #m, which is important to applications shuch as sensors and coupling devices between different fibers.

关键词： mode Central distance of interferential mode patterns of elliptical core two-mode fiber core

Efficient Spherical Wavefront Correction near the Focus for the 0.89 PW/29.0 fs Ti:Sapphire Laser Beam

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Chinese Physics Letters 2011年第2期28卷 85-88页

作者： REN Zhi-Jun LIANG Xiao-Yan YU Liang-Hong LU Xiao-Ming LENG Yu-Xin LI Ru-Xin XU Zhi-Zhan State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800

We demonstrate a new loop system of the spherical wavefront(SW)correction near the beam focus to effectively improve the focusability of 0.89 PW/29.0 fs Ti:sapphire chirped pulse amplification *** wavefront correction,the Strehl ratio is improved to reach 0.91,and the focal spot size using the f/4 off-axis parabola is reduced to 6.34 x 6.94μm^(2)(corresponding to 1.63 x 1.78 times diffraction limitation).With full peak power of 0.89 PW,the peak intensity of 2.59 x 10^(21)W/cm^(2)is *** experimental results show that the SW correction scheme near the beam focus is comparatively simple,economic and high-efficient.

关键词： correction beam spherical

Electric Field Control of Interface Related Spin Splitting in Step Quantum Wells

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Chinese Physics Letters 2009年第7期26卷 263-266页

作者：郝亚非陈涌海郝国栋王占国 Key Laboratory of Semiconductor Materials Science Institute of Semiconductors Chinese Academy of Sciences PO Box 912 Beijing 100083

Spin splitting of the Aly Ga1-y As/GaAs/A1x Ga1-x As/A1-y Ga1-y As （x ≠ y） step quantum wells （ Q Ws） has been theoretically investigated with a model that includes both the interface and the external electric field contribution. The overall spin splitting is mainly determined by the interface contribution, which can be well manipulated by the external electric field. In the absence of the electric field, the Rashba effect exists due to the internal structure inversion asymmetry （SIA）. The electric field can strengthen or suppress the internal SIA, resulting in an increase or decrease of the spin splitting. The step QW, which results in large spin splitting, has advantages in applications to spintronic devices compared with symmetrical and asymmetrical QWs. Due to the special structure design, the spin splitting does not change with the external electric field.

关键词： CONDUCTION SUBBANDS INVERSION ASYMMETRY HETEROSTRUCTURES RASHBA LAYERS INAS

Efficiency-enhanced AlGaInP Light-Emitting Diodes with Thin Window Layers and Coupled Distributed Bragg Reflectors

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Chinese Physics Letters 2011年第6期28卷 305-307页

作者： CHEN Yi-Xin SHEN Guang-Di ZHU Yan-Xu GUO Wei-Ling LI Jian-Jun Optoelectronic Technology Laboratory Beijing University of TechnologyBeijing 100124

A new structure of high-brightness light-emitting diodes(LED)is experimentally *** thin window layer is composed of a 300-nm-thick indium-tin-oxide layer and a 500-nm-thick GaP layer for both current spreading and light *** two coupled distributed Bragg reflectors(DBRs)with one for reflecting normal incidence light and the other for reflecting inclined incidence light which is emitted to the GaAs substrate are employed in the LED *** coupled DBRs in the LED can provide high reflectivity with wide-angle *** efficiency-enhanced AlGaInP LED has the luminance intensity increase of more than 50%compared with conventional LEDs and high reliability with the saturation current 130 mA.

关键词： Efficiency thick reflectivity

Effect of Indium Ambient on Electrical Properties of Mg-Foped AlxGa1-xN

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Chinese Physics Letters 2010年第12期27卷 181-183页

作者：许正昱秦志新桑立雯张延召沈波张国义赵岚张向锋成彩晶孙维国 State Key Laboratory of Artificial Microstructure and Mesoscopic Physics School of Physics Peking University Beijing 100871 Luoyang Optoelectronic Institute PO. Box 030 Luoyang 471009

Mg-doped AlxGa1-xN epilayers were grown on AlN/sapphire templates by metal organic chemical vapor depo- sition （MOCVD） using an indium-assisted growth method. At room temperature, the resistivity of Mg-doped Alo.43Gao.57N epilayer grown under indium （In） ambient is of the order of 10^4Ω.cm, while the resistivity of Mg-doped Al0.43Ga0.57N grown without In assistance is of the order of 10^6Ω.cm. The ultraviolet light-emitting diodes （UV-LEDs） using the In-assisted Mg-doped Al0.43Ga0.57N as the p-type layers were fabricated to verify the function of indium ambient. It is found that there are a lower turn-on voltage and a lower diode series resistance in the UV-LEDs fabricated with p-type Al0.43Ga0.57 N layers grown under In-ambient.

关键词： Metallorganic chemical vapor deposition