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Journal of Materials Science & Technology 2000年第1期16卷 67-70页

作者： Ming CHANG (tianjin institute of Technology, tianjin 300191, china) tianjin institute of Technology Tianjin 300191 China

The values of mosaic block size and microstrain measured by the method of Voigt function are sometimes largely erroneous and difficult to be revised. In this paper, the causes of the 'hook effect' which inevitably exists in the method of Fourier analysis are explained; then the method for resolving this effect is put forward; and finally the method of hypothetical function is used to simplify the method of the Fourier analysis from multi-peak to single-peak. By introducing the parameter m, this method can not only indicate the degree of errors, but also revise them as well, it is simple, clear and able to accomplish the intricate pattern calculation quickly by the aid of computer. In the end, we argue the identity between method of the approximate function and the Fourier analysis, and give a more accurate proportional coefficient k.

关键词： Measurement theory

γ-PHASE IN WC-Co CEMENTED CARBIDES

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中国有色金属学会会刊：英文版 1993年第2期3卷 51-57页

作者： Liu,Shourong tianjin institute of Hard Alloy,tianjin 300222,china

The allotropic transformation process of the γ-phase in WC-Co cemented carbides has been *** of γ-grain and the γ-domain have been proposed forward:The γ-domain is the residual FCC-typeβ-Co grain that failed to transform when cooling alloy sample and γ-base is the HCP-type x-Co transformedmainly by means of diffusion,the outline of the γ-grain is consistent with the newly fromed β-Co grain formedat high *** quantity and distribution of γ-grain domain are related to the cooling rate after sinter-ing and influence the alloys properties.

关键词： WC-Co cemented carbides γ-grain γ-domain

Effect of Fe(III) impurity on the electrochemical performance of LiFePO_4 prepared by hydrothermal process

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Science china(Technological Sciences) 2009年第1期52卷 264-268页

作者： OU XiuQin, XU ShengZhao, LIANG GuangChuan, WANG Li & ZHAO Xia institute of power source & Ecomaterials Science, Hebei University of Technology, tianjin 300130, china institute of power source & Ecomaterials Science Hebei University of Technology Tianjin China

Lithium iron phosphate (LiFePO4) was synthesized from LiOH, FeSO4 and H3PO4 by a hydrothermal process at 180℃. The samples were characterized by X-ray diffraction, scanning electron microscopy and chemical analysis. Electrochemical performance of the samples was tested in terms of charge-discharge capacity and cycling behavior. The results indicated that Fe(III) impurity had obvi- ously effect on the electrochemical properties of LiFePO4, and the formation of Fe3+ was caused by the oxidation of Fe2+ in the dissolving and feeding processes accompanying the increase of pH value. It was found that the precipitation separation was effective in decreasing the content of Fe3+ in the solu- tion of FeSO4 and the sealed feeding was useful in preventing the conversion of Fe2+ to Fe3+. When the content of Fe3+ source exhibited an initial discharge capacity of 154.9 mAh·g-1 at the rate of 0.1 C (1 C = 150 mA·g-1) and the cycling retention rate could reach 98% after 50 cycles at room temperature.

关键词： hydrothermal synthesis lithium iron phosphate (LiFePO4) ferric

β→α Transformation of γ-Phase in Sintered WC-Co Cemented Carbides

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Journal of Materials Science & Technology 1996年第5期12卷 398-400页

作者： Shourong LIU (tianjin institute of Hard Alloy tianjin 300222, china)Yi LIU (Shandong University Jinan 250100, china) tianjin institute of Hard Alloy Tianjin 300222 China Shandong University Jinan 250100 China

Varying the morphology and the structure of γ-phase (Co-base Co-W-C solid solution) by means of altering the cooling rate and the preparing method of liquid sintered WC-Co cemented carbides samples, the mechanism of fcc→hcp transformation of γ-phase in WC-Co alloy has been explored. The results show that, the cooling rate is an important affecting factor on fcc→hcp transformation of γ-phase and the fcc→hcp transformation is mainly a diffusive type when cooling WC-Co samples above room temperature

关键词： WC Co Phase in Sintered WC-Co Cemented Carbides Transformation of

Experimental study on high-voltage solar array sustained arc discharge induced by high charging

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Science china(Technological Sciences) 2007年第2期50卷 213-220页

作者： LI Kai1,2, XIE ErQing1, WANG Li2, LIU YanXia1, YANG Yang1, SUN YanZheng3, CUI XinYu3 & MAI ShengLi2 1 School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, china 2 Lanzhou institute of Physics, Lanzhou 730000, china 3.tianjin institute of power source, tianjin 3.03.1. china School of Physical Science and Technology Lanzhou University Lanzhou China Lanzhou institute of Physics Lanzhou China tianjin institute of power source Tianjin China

It has been reported that sustained arc discharge induced by electrostatic discharge (ESD) could cause permanent damage to high-power and high-voltage solar array of spacecrafts. The paper focuses on ESD simulating experiments on Si and GaAs samples, and induces sustained arc discharge. The physical mechanism of sustained arc discharge is discussed by comparing the charging/discharging phenomena between Si and GaAs samples. The experiments show that sustained arc discharge can produce a permanent short-circuit channel between solar cell strings through which the solar array’s photovoltaic power may flow out sustainedly. The analyses show that sustained arc discharge strongly depends on solar array structure, solar array operating voltage, ESD characteristics and cell materials. Keywords high-voltage solar array - electrostatic discharge - sustained arc discharge - mechanism Supported by the National Laboratory of Vacuum, Cryogenics Technology and Physics (Grant No. 51475030504DZ2801), and the National High Technology Development Program of china (Grant No. 2002AA732158)

关键词： high-voltage solar array electrostatic discharge sustained arc discharge mechanism

Second mode unstable disturbance measurement of hypersonic boundary layer on cone by wavelet transform

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Acta Mechanica Sinica 2011年第4期27卷 488-493页

作者： Jian Han.Nan Jiang.Yan Tian Department of Mathematics,tianjin University,300072 tianjin,china Department of Mechanics,tianjin University,300072 tianjin,china tianjin Key Laboratory of Modern Engineering Mechanics,300072 tianjin,china State Key Laboratory of Nonlinear Mechanics,institute of Mechanics,Chinese Academy of Sciences,100190 Beijing,china Department of Mathematics Tianjin University Tianjin China Department of Mechanics Tianjin University Tianjin China tianjin Key Laboratory of Modern Engineering Mechanics Tianjin China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing China

Experimental investigation of hypersonic boundary layer instability on a cone is performed at Mach number 6 in a hypersonic wind tunnel. Time series signals of instantaneous fluctuating surface-thermal-flux are measured by Pt-thin-film thermocouple temperature sensors mounted at 28 stations on the cone surface in the streamwise direction to investigate the development of the unstable disturbance. Wavelet transform is employed as a mathematical tool to obtain the multi-scale characteristics of fluctuating surfacethermal-flux both in the temporal and spectrum space. The conditional sampling algorithm using wavelet coefficient as an index is put forward to extract the unstable disturbance waveform from the fluctuating surface-thermal-flux *** generic waveform for the second mode unstable disturbance is obtained by a phase-averaging technique. The development of the unstable disturbance in the streamwise direction is assessed both in the temporal and spectrum space. Our study shows that the local unstable disturbance detection method based on wavelet transformation offers an alternative powerful tool in studying the hypersonic unstable mode of laminar-turbulent transition. It is demonstrated that, at hypersonic speeds, the dominant flow instability is the second mode, which governs the course of laminar-turbulent transition of sharp cone boundary layer.

关键词： Hypersonic boundary layer. Sharp cone Insta-bility Wavelet transform

Influence of p-layer on the performance of n-i-p μc-Si:H thin film solar cells

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Science china(Physics,Mechanics & Astronomy) 2010年第11期53卷 2042-2046页

作者： YUAN YuJie 1,2,ZHANG KaiLiang 1,2,WEI Zhen 1,2 & GENG XinHua 3 1 College of Electronics Information Engineering,tianjin University of Technology,tianjin 300384,china 2 tianjin Key Laboratory of Film Electronic and Communication Devices,tianjin University of Technology,tianjin 300384,china 3 institute of Photo-Electronics Thin Film Devices and Technique,Nankai University,tianjin 300071,china College of Electronics Information Engineering Tianjin University of Technology Tianjin China tianjin Key Laboratory of Film Electronic and Communication Devices Tianjin University of Technology Tianjin China institute of Photo-Electronics Thin Film Devices and Technique Nankai University Tianjin China

The high pressure radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process was adopted to prepare the n-i-p microcrystalline silicon solar cells,the influence of p-type layers on the performance of the solar cells was investigated,and the optimum p layer suited to the n-i-p microcrystalline silicon solar cells was *** experimental results demonstrate that the performance of the solar cells can be highly affected by the structural and optical properties of the p-layers,and the performance of solar cells can be greatly improved by optimizing p *** have achieved an initial active-area efficiency of 8.17% (V oc =0.49 V,J sc =24.9 mA/cm 2 ,FF=67%) for the μc-Si:H single-junction n-i-p solar cells and an initial active-area efficiency of 10.93% (V oc =1.31 V,J sc =13.09 mA/cm 2 ,FF=64%) for the a-Si:H/μc-Si:H tandem n-i-p solar cells.

关键词： microcrystalline silicon solar cells quantum confinement effect p-type layers

OBSERVATIONS ON DEFORMATION BEHAVIOR OF HIGH PERFORMANCE FIBERS BY POLARIZING OPTICAL MICROSCOPY

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Chinese Journal of Polymer Science 2000年第1期18卷 81-86页

作者： Chang-fa Xiao Yu-feng Zhang Department of Materials Science, tianjin institute of Textile Science and Technology, tianjin 300160, china 天津纺织工学院天津

By means of polarizing optical microscopy (POM), deformation behavior of four kinds of fibers, i.e, ultra high molecular weight polyethylene (UHMW-PE) fiber, polyvinyl alcohol (PVA) fiber, polyethylene terephthalate (PET) fiber, and wholly aromatic (rho-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid) copolyester [P(HBA/HNA)]/PET (ACPET blend) fiber, in axial compression, axial impacting, and bending was observed. In compression, kink bands formed at an angle of 55-60 degrees ro the fiber axis in 10-times-drawn UHMW-PE fiber, 75-80 degrees in 40-times-drawn sample, 80 degrees in PVA fiber, and 90 degrees in the ACPET blend fiber. In impacting and bending, band angles of UHMW-PE, PVA and PET fibers are nearly the same as those formed in compression, indicating that slip systems do not change. For any of the four kinds of fiber, band spacing exhibits great differences in compression, in impacting, and in bending, which may be attributed to the differences in the degrees of strain or stress concentration.

关键词： high performance fiber axial compression axial impacting bending

RISK ANALYSIS AND MANAGEMENT OF URBAN RAINSTORM WATER LOGGING IN tianjin

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Journal of Hydrodynamics 2006年第5期18卷 552-558页

作者： HAN Su-qin XIE Yi-yang LI Da-ming LI Pei-yan SUN Mei-ling College of Environmental Science and Engineering Nankai University Tianjin 300071 China Tianjin Meteorology Institute Tianjin 300074 China tianjin Meteorology institute Tianjin 300074 China School of Civil Engineering Tianjin University Tianjin 300072 China

The risk analysis of urban rainstorm water logging facing tianjin city by using methods of probability, investigation and numerical simulation was carried out in this article. Firstly, a mathematical model for the urban rainstorm water logging was established on the basis of one- and two-dimensional unsteady flow theory and the technique of non-structural irregular grid division, Secondly, the precipitation over heavy rain was divided into seven grades, the experiential expression of frequency and rain grades was got according to the observed rainfall from May 1918 to October 1998. Thirdly, the mathematical model was used to simulate various rain process according to the features of the rainstorm and the draining rule, based on the simulated maximum water depths, 3 class of disaster extents were established, the disaster risks were mainly in Class Ⅰ and Class Ⅱ, The risk analysis of water logging on traffic were primarily evaluated, and finally, some management and mitigation measures of the urban rainstorm water logging disaster were discussed.

关键词： urban rainstorm water logging mathematical model traffic disaster risk analysis,tianjin

An approach to determining the local boundaries of voltage stability region with wind farms in power injection space

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Science china(Technological Sciences) 2010年第12期53卷 3232-3240页

作者： MU YunFei & JIA HongJie Key Laboratory of power System Simulation and Control of Ministry of Education, tianjin University, tianjin 300072, china Key Laboratory of power System Simulation and Control of Ministry of Education Tianjin University Tianjin China

A new approach to determining the local boundaries of voltage stability region in power injection space (IVSR) for power system with wind farms is presented. It can be used for power system voltage stability analysis and on-line security assessment with considering the output uncertainty of the wind farms. Firstly, power flow tracing and double dispatching are used to determine the generators that are closely related to the wind farms, in order to balance the power fluctuations caused by the wind speed variation. Then, modal analysis is used to get the key generators to achieve an effective dimension reduction for IVSR. Finally, the forecasting output power (or wind speed) of wind farms is divided into several intervals. For each interval, the corresponding local IVSR boundaries can be calculated by the method based on small disturbance. Moreover, parallel process is used to accelerate the computing speed. The presented approach is validated by several power systems. It can be revealed that the approach can give the local IVSR boundaries at different wind speeds and has a good engineering application prospect.

关键词： voltage stability region power flow tracing modal analysis parallel process