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Preparation of NiFe binary alloy nanocrystals for nonvolatile memory applications

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Science China(Technological Sciences) 2010年第9期53卷 2320-2322页

作者： WANG Li,SUN HongFang,ZHOU HuiHua & ZHU Jing beijing National center for Electron Microscopy Laboratory,{2. of Materials Science and engineering,tsinghua university,beijing 100084,China 1. beijing National center for Electron Microscopy Laboratory Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

In this work,an idea which applies binary alloy nanocrystal floating gate to nonvolatile memory application was *** relationship between binary alloy’s work function and its composition was discussed theoretically.A nanocrystal floating gate structure with NiFe nanocrystals embedded in SiO2.dielectric layers was fabricated by magnetron *** micro-structure and composition deviation of the prepared NiFe nanocrystals were also investigated by TEM and EDS.

关键词： nanocrystal nonvolatile memory work function magnetron sputtering

Large eddy simulation of stably stratified turbulence

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Science China(physics,Mechanics & Astronomy) 2010年第1期53卷 135-146页

作者： SHEN Zhi, LI YuPeng, CUI GuiXiang & ZHANG ZhaoShun department of engineering Mechanics, {2., beijing 100084, China 1. department of engineering Mechanics Tsinghua University Beijing 100084 China

Stable stratification turbulence, as a common phenomenon in atmospheric and oceanic flows, is an important mechanism for numerical prediction of such flows. In this paper the large eddy simulation is utilized for investigating stable stratification turbulence numerically. The paper is expected to provide correct statistical results in agreement with those measured in the atmosphere or ocean. The fully developed turbulence is obtained in the stable stratification fluid by large eddy simulation with different initial velocity field and characteristic parameters, i.e. Reynolds number Re and Froude number Fr. The evolution of turbulent kinetic energy, characteristic length scales and parameters is analyzed for investigating the development of turbulence in stable stratification fluid. The three-dimensional energy spectra, horizontal and vertical energy spectrum, are compared between numerical simulation and real observation in the atmosphere and ocean in order to test the reliability of the numerical simulation. The results of numerical cases show that the large eddy simulation is capable of predicting the properties of stable stratification turbulence in consistence with real measurements at less computational cost. It has been found in this paper that the turbulence can be developed under different initial velocity conditions and the internal wave energy is dominant in the developed stable stratification turbulence. It is also found that the characteristic parameters must satisfy certain conditions in order to have correct statistical property of stable stratification turbulence in the atmosphere and ocean. The Reynolds number and Froude number are unnecessarily equal to those in atmosphere or ocean, but the Reynolds number must be large enough, say, greater than 10 2., and Froude number must be less than 0.1. The most important parameter is ReFr 2.which must be greater than 10.

关键词： stratified turbulence internal wave potential vortex large eddy simulation

Local and non-local sources of airborne particulate pollution at beijing——The ratio of Mg/Al as an element tracer for estimating the contributions of mineral aerosols from outside beijing

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Science China Chemistry 2005年第3期48卷 253-264页

作者： HAN Lihui1, ZHUANG Guoshun1,2.3, SUN Yele1 & WANG Zifa3 1. The center for Atmospheric Environmental Study, department of Chemistry, {2. Normal university, {2. 100875, China 2. center for Atmospheric Chemistry Study, department of Environmental Science & engineering, Fudan university, Shanghai 2.0433, China 3. LAPC/NZC, Institute of Atmospheric physics, CAS, {2. 10002., China 1. The center for Atmospheric Environmental Study Department of Chemistry Beijing Normal University 100875 Beijing China 2. center for Atmospheric Chemistry Study Department of Environmental Science & Engineering Fudan University 200433 Shanghai China 3. Institute of Atmospheric physics CAS LAPC/NZC 100029 Beijing China

A new element tracer technique has firstly been established to estimate the contri-butions of mineral aerosols from both inside and outside beijing. The ratio of Mg/Al in aerosol is a feasible element tracer to distinguish between the sources of inside and outside beijing. Mineral aerosol, inorganic pollution aerosol mainly as sulfate and nitrate, and organic aerosol are the major components of airborne particulates in beijing, of which mineral aerosol accounted for 32.―67% of total suspended particles （TSP）, 10%―70% of fine particles （PM2.5）, and as high as 74% and 90% of TSP and PM2.5, respectively, in dust storm. The sources from outside beijing contributed 62. （38%―86%） of the total mineral aerosols in TSP, 69% （52.―90%） in PM10, and 76% （59%―93%） in PM2.5 in spring, and 69% （52.―83%）, 79% （52.―93%）, and 45% （7%―79%） in TSP, PM10, and PM2.5, respectively, in winter, while only2.% in summer and autumn. The sources from outside beijing contributed as high as 97% during dust storm and were the dominant source of airborne particulates in beijing. The contributions from outside Bei-jing in spring and winter are higher than those in summer, indicating clearly that it was related to the various meteorological factors.

关键词： mineral aerosol local sources non-local sources dust storm re-suspended dust element tracer technique.

Bitstream decoding and SEU-induced failure analysis in SRAM-based FPGAs

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Science China(Information Sciences) 2012年第4期55卷 971-982页

作者： WANG ZhongMing 1,2.YAO ZhiBin 2.GUO HongXia 2.& LV Min 1 1 department of engineering {2.,tsinghua university,beijing 100084,China 2.Northwest Institute of Nuclear Technology,Xi'an 71002.,China 1. department of engineering {2. Tsinghua University Beijing 100084 China2. Northwest Institute of Nuclear Technology Xi’an 710024 China

Reconfigurable SRAM-based FPGAs are highly susceptible to radiation induced single-event upsets (SEUs) in space *** bit flip in FPGAs configuration memory may alter user circuit permanently without proper bitstream reparation,which is a completely different phenomenon from upsets in traditional memory *** is important to find the relationship between a programmable resource and corresponding control bit in order to understand the impact of this *** this paper,a method is proposed to decode the bitstream of FPGAs from Xilinx Corporation,and then an analysis program is developed to parse the netlist of a specific design to get the configuration state of occupied programmable logic and *** that,an SEU propagation rule is established according to the resource type to identify critical logic nodes and paths,which could destroy the circuit topological *** decoded relationship is stored in a *** database is queried to get the sensitive bits of a specific *** result can be used to represent the vulnerability of the system and predict the on orbit system failure *** analysis tool was validated through fault injection and accelerator irradiation experiment.

关键词： radiation effect single-event effect single-event upset SRAM-based FPGA fault injection

KTN thin films prepared by pulsed laser deposition on transparent single crystal quartz(100)

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Science China(physics,Mechanics & Astronomy) 2005年第1期48卷 33-43页

作者： WANG Xiaodong, PENG Xiaofeng & ZHANG Duanming Laboratory of Phase Change and Interfacial Transport Phenomena, department of Thermal engineering, {2., beijing 100084, China department of physics, Huazhong university of Science and Technology, Wuhan 430074, China 1. Laboratory of Phase Change and Interfacial Transport Phenomena Department of Thermal Engineering Tsinghua University 100084 Beijing China 2. department of physics Huazhong University of Science and Technology 430074 Wuhan China

Using the Sol-Gel method to produce the KTN ultrafine powder and the sintering technique with K2. atmosphere to prepare KTN ceramics as the targets instead of the KTN single crystal, highly oriented KTN thin films were produced on the transparent single crystal quartz (100) by the pulsed laser deposition (PLD). Since the thermal stress sustained by the quartz is relatively small, the limit temperature of the quartz substrates(300℃) is much lower than that of the P-Si substrates (560℃); the prepared thin film is at amorphous state. Increasing the pulsed laser energy density in the process incorporated with annealing the film after deposition at different temperatures converts the amorphous films into crystal. The optimal pulsed laser energy density and annealing temperature were 2.0 J/cm2.and 600℃, respectively. A discussion was made to understand the mechanism of film production at relatively low substrate temperature by PLD and effects of the annealing temperatures on the forming of the perovskite phase, and optimal conditions for the orientation of the crystal grain.

关键词： PLD technology, KTN thin film, single crystal quartz, pulsed energy density, annealing, perovskitephase.

Numerical simulation analysis of Guixi copper flash smelting furnace

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Rare Metals 2002年第4期21卷 260-265页

作者： LIXinfeng MEIChi 等 NationalCIMSengineeringResearchcenter TsinghuaUniversityBeijing100084China departmentofHeatengineering CentralSouthUniversityChangsha410083China

A numerical simulation analysis for reactions of chalcopyrite and pyriteparticles coupled with momentum, heat and mass transfer between the particle and gas in a flashsmelting furnace is presented. In the simulation, the equations governing the gas flow are solvednumerically by Eular method. The particle phase is introduced into the gas flow by theparti-cle-source-in-cell technique (PSIC). Predictions including the fluid flow field, temperaturefield, concentration field of gas phase and the tracks of particles have been obtained by thenumerical simulation. The visualized results show that the reaction of sulfide particles is almostcompleted in the upper zone of the shaft within 1.5 m far from the central jet distributor (CJD)type concentrate burner. The simulation results are in good agreement with data obtained from aseries of experiments and tests in the plant and the error is less than 2..

关键词： numerical simulation flash smelting furnace copper

Archean relic body at lower crust in Sulu area:Evidence from magnetic data

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Chinese Science Bulletin 2003年第6期48卷 589-593页

作者： WU Qifan1,2. LU Fengxiang3, LIU Qingsheng3, ZHENG Jianping3, WANG Maoji2.& WU Wenli4 1. department of engineering {2., tsinghua university, beijing 100084, China 2. Aero Geophysical Survey & Remote Sensing center, beijing 100083, China 3. China university of Geosciences, Wuhan 430074, China 4. Institute of Geophysical & Geochemical Exploration, Langfang 065000, China Aero Geophysical Survey & Remote Sensing center Beijing 100083 China China university of Geosciences Wuhan 430074 China Institute of Geophysical & Geochemical Exploration Langfang 065000 China department of engineering {2. Tsinghua University Beijing 100084 China

After the new 1︰1000000 aero magnetic data were processed and the three-dimensional inversion work was carried out, a vast high magnetic body northwestward was discovered. The magnetic body is located at the depth of about 2. km on the west side of Tanlu fault and at about 2. km on the east side of Tanlu fault beneath the Sulu area. There is a difference of vertical distance of 3—5 km in depth between both sides. We think that the magnetic body is an Archean metamorphic plate and belongs to the North China block. The discovery of the magnetic body is significant for us to reconstruct the structure model of the Sulu orogenic belt, delineate the suture of collision between the North China block and the Yangtze block, and estimate the depth of slipping surface when the eastside of Tanlu fault moved northward.

关键词：苏鲁地区地壳下层太古代残余体地球物理调查区域性磁场三维反演苏鲁造山带郯鲁断裂带大别-苏鲁超高压变质带

The Process of TiB_2.Cu Composite Phase and Structure Formation during Combustion Synthesis

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Journal of Wuhan university of Technology(Materials Science) 2006年第4期21卷 113-116页

作者：徐强 School of Materials Science and engineering Beijing Insitute of TechnologyBeijing 100081China

The reaction process of combustion synthesis for TiB2.-Cu was investigated in detail using combustion-wave arresting experiment, X-ray diffraction （ XRD ） analysis, SEM analysis and differential thermal analysis （ DTA ）. The XRD analysis results for the different parts of the quenched specimen show that TiCux intermetallic phase firstly forms with the propagation of combustion wave, and then Ti1.87 B50 and Ti3B4 metastable phases come forth due to the diffusion of B atoms and finally the stable TiB2.phase forms because of the continuous diffusion of B atoms. The formation of TiB2.phase is uot completed by one step, but undergoes several transient processes. The process of reaction synthesis for Ti-B-Cu ternary system can be divided into three main stages： melting of Cu and Ti , and the formation of Cu- Ti melt and few TiCux , TiBx intermetallic phases ; large numbers of TiCux intermetallic phases formation and some fine TiB2.particles precipitation ; and the TiB2.particles coarsening and the stable TiB2.and Cu two phases formation in the final product.

关键词： combustion synthesis reaction process TiB2.phase combustion-wave arresting experiment

Effects of radial velocity on line profiles and images from the standard thin disk

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Science China(physics,Mechanics & Astronomy) 2010年第1期53卷 155-162页

作者： PAN CaiJuan department of physics and Telecommunication {2., Baise university, Baise 533000, China center for astrophysics, university of Science and Technology of China, Hefei 2.0051, China 1. department of physics and Telecommunication {2. Baise University Baise 533000 China2. Center for Astrophysics University of Science and Technology of China Hefei 230051 China

This paper has derived the general formulae of observed line profiles based on the effects of radial velocity on the standard thin disk fluid around a rotating black hole. Through the ray-tracing method the line profiles of different parameters have been calculated. Comparison of the line profiles with and without a radial velocity shows that the effects of radial velocity on line profiles cannot be neglected in most cases. In both cases the accretive disk imaging shape remains unchanged.

关键词： standard thin disk radial velocity Kerr metric line flux