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Anomalous behaviour of long-time increase in diffraction efficiency of photorefractive grating in Ce：BaTiO3 in dark

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Chinese Physics B 2006年第4期15卷 729-734页

作者：张嘉文张明徐英洪治 Centre for Optical and Electromagnetic research State Key Laboratory of Modern Optical instrumentation Zhejiang Provincial Key lab Zhejiang University Hangzhou 310027 China of Optic Fiber Communication Technology Zhejiang University of Technology Hangzhou 310032 China

Anomalous long-time increase of the diffraction efficiency is observed in dark-decay experiments of photorefractive gratings in Ce：BaTiO3. It is deduced that a phase-conjugate beam is induced by the writing beam at acute angle to the ＋c axis of the crystal and it interferes with the other writing beam to form a second grating which is perpendicular to the first grating formed by the interference between two writing beams. The rising behaviour of the diffraction efficiency results from the different decay rates of these two photorefractive gratings. Furthermore, a simplified model of two gratings, both induced by two deep traps, is proposed to account for this phenomenon and the fitting results agree well with the experimental results.

关键词： dark decay photorefractive grating two deep-trap model Ce:BaTiO3

Properties Evolution of a Powder Metallurgical Titanium Alloy with Yttrium Addition

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稀有金属材料与工程 2011年第S3期40卷 298-300页

作者： Liu Haiyan1, Tang Huiping1, He Weiwei1, Liu Yanbin2, Jia Wenpeng1, Liu Yong2 1State Key laboratory for Porous Metals Materials, Northwest Institute for Nonferrous Metal research, Xi′an 710016, China 2 State Key laboratory for Powder Metallurgy, Central South University, Changsha 410083, China NW Inst Nonferrous Met Res State Key Lab Porous Met Mat Xian 710016 Peoples R China Cent S Univ State Key Lab Powder Met Changsha 410083 Hunan Peoples R China

P/M Ti-Fe-Mo-Y alloys with different Rare-earth Y Content are prepared by blend element method, its sintering and hot deformation behaviors are studied together with microstructure and mechanical properties. The microstructures and properties of the alloying titanium were testified by the analysis of Optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM).The result indicated that Y element absorbs free oxygen and purify the Ti powder surface, promoting densification process. With appropriate vacuum and temperature, the blend element metal powder sintering relative density can reach more than 97%. Microstructure and mechanical properties analysis shown that Y element composed Y2O3 particles which refine grains and improve plasticity, elevate alloy distortion ability. After hot deformation, grains crashed and flow line appears, the mechanical properties of Ti-Fe-Mo-Y alloy prompted which also validated by large amount of dimples appear in tensile fracture surface.

关键词： P/M Ti-Fe-Mo-Y alloy blend element method hot deformation

SERS activity of Au nanoparticle films

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Chinese Optics Letters 2009年第4期7卷 355-356页

作者：洪昕杜丹丹 National Key lab of Measurement Technology and Precision Instrument College of Precision Instrument and Opto-Electronics EngineeringTianjin University

The core-shell gold nanoparticle film is fabricated by using nanolithography and self-assembly monolayer technology. The film exhibits unique optical properties and has strong surface enhanced Raman scattering （SERS） activity. The relationship between nanostructure and surface electrical field is studied by employing pyridine as the SERS probe. It is found that particle size and inter-particle space are important factors. The enhancement ratio is measured to be more than 10^4.

关键词： Metallic films Monolayers Nanoparticles Optical properties Raman scattering Space probes Surfaces

On-chip mechanical computing:status,challenges,and opportunities

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Chip 2023年第1期2卷 58-72页

作者： Luming Wang Pengcheng Zhang Zuheng Liu Zenghui Wang Rui Yang Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054China University of Michigan-Shanghai Jiao Tong University Joint Institute Shanghai Jiao Tong UniversityShanghai 200240China School of Electronic Information and Electrical En-gineering Shanghai Jiao Tong UniversityShanghai 200240China State Key laboratory of Electronic thin films and Integrated Devices University of Elec-tronic Science and Technology of ChinaChengdu 610054China

With increasing challenges towards continued scaling and improve-ment in performance faced by electronic computing,mechanical com-puting has started to attract growing *** advantage of the mechanical degree of freedom in solid state devices,micro/nano-electromechanical systems(MEMS/NEMS)could provide alternative solutions for future computing and memory systems with ultralow power consumption,compatibility with harsh environments,and high *** this review,MEMS/NEMS-enabled memories and logic processors were surveyed,and the prospects and challenges for future on-chip mechanical computing were also analyzed.

关键词： MEMS/NEMS switch MEMS/NEMS resonator Mechanical computing Mechanical memory Low-power computing

Experiments on Development of Channel Pattern in the Process of River Reformation

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四川大学学报（工程科学版） 2005年第S1期37卷 128-132页

作者： ZHANG Junyong CHEN Li LIU Yucheng DING Zhiliang(State Key lab.of Water Resources and Hydropower Eng.Sci.,Wuhan Univ.,Wuhan 430072,China) lab. of Water Resources and Hydropower Eng. Sci. Wuhan Univ. Wuhan 430072 China

The changing of flow conditions caused by construction of hydro-projects will result in river's refor- mation and development of channel *** this paper,the development of channel pattern in the process of reformation is studied by means of flume *** of slope,grain size,angle-of-inflow,dis- charge and discharge process are comprehensively analyzed according to the experimental *** was found that the channel would be widened as the river slope or discharge increased and grain s...

关键词： reformation process channel pattern angle-of-inflow discharge process

Effects of vibration and grain refiner on microstructure of semisolid slurry of hypoeutectic Al-Si alloy

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中国有色金属学会会刊：英文版 2008年第4期18卷 842-846页

作者：赵君文吴树森谢礼志安萍毛有武 State Key lab of Materials Processing and Die & Mould Technology Huazhong University of Science and TechnologyWuhan 430074China

The effects of vibration and grain refiner on the microstructure of semisolid slurry of hypoeutectic Al-Si alloy were studied. The impact of vibration on the convection of liquid was conducted by using a system of water-particle tracer. The 356 melt at temperature of 630-660 ℃ with or without grain refiner Al-5%Ti-1%B was poured into a metal cup as the vibrating vessel, then it was cooled to 590-610 ℃ in the semisolid zone and kept for some time, subsequently vibration with different frequencies was applied. The results show that the primary α(Al) particles become finer and rounder with the increase of vibration frequency. The slurry with primary α(Al) equivalent particle diameter(EPD) of about 90 μm and average shape coefficient(ASC) of about 0.5 can be prepared under vibration of 20 Hz. With the combined action of vibration and grain refiner Al-5Ti-B, even smaller and rounder spheroids with EPD of about 85 μm and ASC of about 0.6 are obtained.

关键词：亚共晶铝硅合金机械振动半固态金属晶粒细化剂微观结构

Reduction of 1-3 mm iron ore by H_2 in a fluidized bed

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International Journal of Minerals,Metallurgy and Materials 2009年第6期16卷 620-625页

作者： Jian-ming Pang Pei-min Guo Pei Zhao Chao-zhen Cao Ding-guo Zhao Duo-gang Wang The State Key laboratory for Advanced Steel Processes and Materials Central Iron and Steel Research Institute Beijing 100081 China

The reduction of 1-3 mm fine powder of iron ore by H2 was conducted in a lab-fabricated kg class high temperature fluidized bed. The results show that the differential pressure in the fluidized bed, which has small fluctuation with time, increases with the increase of gas flowing velocity. The utilization ratio of gas decreases when the reaction lasts longer time indicating that the reaction is faster at the beginning of reduction and becomes slower in the latter process. The higher the reaction temperature is, the higher the utilization ratio of gas is, but the difference of utilization ratio among the different temperatures becomes smaller with time. The utilization ratio of gas and the metallization ratio can reach 9% and 84% respectively at 750℃ for 20 min, which shows the reduction reaction by H2 is very fast. The increase of metallization ratio with gas velocity performs quite good linearity, which shows that a higher velocity of reducing gas can be used to improve the productivity of the reactor when H2 is used as reducing gas. With the increase of charge height, the metallization ratio decreases, but the utilization ratio of gas increases. The reaction temperature can be reduced to 700-750℃ from 800-850℃ when H2 is used as reducing gas.

关键词： hydrogen fluidized bed fine powder iron ore ironmaking reduction reaction

Surface modification of (Tb_(0.3)Dy_(0.7))Fe_(1.95) alloy by ion nitriding process

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Journal of Rare Earths 2009年第2期27卷 240-243页

作者：李扩社李红卫严辉于敦波王丰瀛张世荣张国成 National Engineering research Center for Rare Earth Materials General Research Institute for Non-Ferrous Metalsand Grirem Advanced Materials Co.Ltd.Beijing 100088China College of Materials Science and Engineering Beijing University of TechnologyBeijing 100022China

Effect of ion nitriding modification on surface hardness, corrosion resistance and magnetostriction of （Tb0.3Dy0.7）Fe1.95 alloy was investigated. Results demonstrated that a 100-200 nm thick nitrided layer was formed on the sample surface by ion nitriding treatment, which improved obviously surface hardness, wear, and corrosion resistance properties of （Tb0.3Dy0.7）Fe1.95 alloys. The surface hardness was increased from HV587 to HV622 after ion nitriding at 650 K for 6 h. Furthermore, ion nitriding treatment had almost no influence on mag- netostrictive performance as the nitrided layer was quite thin and the treatment temperature was not too high. The results might provide us a new approach for surface modification of （Tb0.3Dy0.7）Fe1.95 alloy.

关键词： magnetostfiction ion nitriding surface modification (Tb0.3Dy0.7)Fe1.95 rare earths

Experiment on the Effect of Sediment Concentration on Flow Structure

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四川大学学报（工程科学版） 2005年第S1期37卷 41-45页

作者： Chen, Li Wu, Menwu Deng, Xiaoli Huang, Rongmin lab. of Water Resources and Hydropower Eng. Sci. Wuhan Univ. Wuhan 430072 China

The paper studies on the sediment-laden flow by using *** calibration has been conducted to determine the relationship between backscattered signal strength and sediment concentration. Based on the experimental data,the interactions between sediment and fluid in open channel flow are investi- *** experiment shows that there exist inner relation between sediment concentration and turbulence, and the relationship is distinctry related to the diameter of particle as well as the flow co...

关键词： turbulence intensity mean velocity sediment concentration flow structure