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Preparation of semi-solid AlSi7Mg alloy slurry with big capability

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Rare Metals 2010年第6期29卷 642-645页

作者： LI Sha and MAO Weimin school of Materials science and engineering,university of science and technology Beijing,Beijing 100083,china school of Materials science and engineering University of Science and Technology Beijing Beijing China

Semi-solid AlSi7Mg alloy slurry was prepared by low superheat pouring and weak traveling-wave electromagnetic *** effects of pouring temperature and stirring power on the microstructure of AlSi7Mg alloy slurry were *** results show that the semi-solid AlSi7Mg alloy slurry of 5 kg can be *** new technology can save energy and make the pouring process *** the pouring temperature is decreased at a stirring power of 0.41 kW,the shape of primary α-Al grains gradually changes from dendritic-like to *** the alloy melt is poured at the temperature（630°C） with a certain superheat,the pouring process becomes easier,and the spherical microstructure of AlSi7Mg alloy slurry can be prepared by the weak traveling-wave electromagnetic *** the pouring temperature is 630°C,increasing the stirring power appropriately can result in better spherical primary α-Al grains,but if the stirring power is increased to a certain value（1.72 kW）,the shape of primary α-Al grains does not obviously improve when the stirring power is continually increased.

关键词： aluminum alloys metal forming semisolid slurry electromagnetic stirring microstructure

Analysis on the Characteristic Properties of PEDOT Nano-particle Based on Reversed Micelle Method

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Journal of Wuhan university of technology(Materials science) 2011年第3期26卷 422-428页

作者：郑华靖 State Key Laboratory of electronic Thin Films&Integrated Devices School of Optoelectronic InformationUniversity of Electronic Science and Technology of China

Based on the study of a new type of conducting polymer poly （3,4-ethylenedioxythiophene）（PEDOT）,we focussed on the preparation and characteristics of PEDOT nanoparticles made by reversed micelle ***,we deeply investigated the optical,electrical and the thermal stability of PEDOT *** main results are as follows： the small-sized PEDOT nanoparticles were prepared and utilized by different methods,such as ultraviolet/visible （UV-Vis） spectroscopy,Fourier-transform infrared （FT- IR） spectrum,scanning electron microscopy（SEM） and so *** results show that the amount of oxidizer,ultrasonic treatment,polymerizing temperature and doping degree can influent morphology,electrical ability and gas sensitivity of PEDOT *** Bragg peaks of nanoparticles at 6.7°,12.7°,25° were observed by XRD and the better orientation of molecular chain was attributed to the effective doping of toluene-p-sulfonic acid,which also resulted in an enhancement of thermal stability of nanoparticles than conventional PEDOT.

关键词： poly (3 4-ethylenedioxythiophene) conducting polymer reversed micelle nano-particle photoelectric properties thermal stability

Epidemic dynamics on complex networks

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Progress in Natural science:Materials International 2006年第5期16卷 452-457页

作者： ZHOU Tao , FU Zhongqian, and WANG Binghong (Department of electronic science and technology, university of science and technology of china, Hefei 230026, china Department of Modern Physics, university of science and technology of china, Hefei 230026, china) Department of electronic science and technology University of Science and Technology of China Hefei 230026 China Department of Modern Physics University of Science and Technology of China Hefei 230026 China

Recently, motivated by the pioneer work in revealing the small-world effect and scale-free property of various real-life networks, many scientists devote themselves to studying complex networks. One of the ultimate goals is to understand how the topological structures affect the dynamics upon networks. In this paper, we give a brief review on the studies of epidemic dynamics on complex networks, including the description of classical epidemic models, the epidemic spread on small-world and scale-free networks, and network immunization. Finally, perspectives and some interesting problems are proposed.

关键词： epidemic dynamics complex networks critical value immunization small-world effect scale-free property.

Kinetics analysis of volume phase transition of intelligent neutral thermo-sensitive hydrogels

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science china(Physics,Mechanics & Astronomy) 2008年第5期51卷 532-540页

作者： WANG XiaoGui1 & LI YiQuan2 1 College of Mechanical engineering,Zhejiang university of technology,Hangzhou 310032,china 2 school of Mechanical & electronic engineering,Changchun university of science and technology,Changchun 130022,china College of Mechanical engineering Zhejiang University of Technology Hangzhou China school of Mechanical & electronic engineering Changchun University of Science and Technology Changchun China

In this work,utilizing the first law of thermodynamics and the Flory mean-field theory,the kinetic deformation studies concerning the volume phase transition of the neutral thermo-sensitive hydrogels were performed *** hydrogel was assumed as a biphasic mixture medium in the framework of the continuum mixture *** the energy conservation of the thermodynamics system of the hydrogel,the governing equations for the kinetics of the nonlinear large deforma-tion were *** explicit analytical expressions of the effective stress tensor and the chemical potential of the fluid of the thermo-sensitive hydrogel PNIPA were also obtained from the Helmholtz free energy,which can model the steady-static volume phase transition quantitatively.

关键词： thermo-sensitive hydrogel volume phase transition effective stress energy conservation

PHASE-LOCKING OF HIGH POWER GYROTRON OSCILLATOR

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Journal of electronics(china) 1996年第1期13卷 89-96页

作者： Tang Changjian (Department of Applied Physics, chengdu university of science & technology of china, chengdu 610065)Yang Zhonghai Liu Pukun(Institute of High Energy electronics, university of electronic science & technology of china, chengdu 610054) Department of Applied Physics Chengdu University of Science & Technology of China Chengdu Institute of High Energy electronics University of Electronic Science & Technology of China Chengdu

The phase-locking process is studied for high-power gyrotron oscillator driven by an external signal. The phase-locking nonlinear differential equations are derived, and the condition of phase-locking is shown and analyzed. The phase-locking signal can be introduced after gyrotron oscillates into saturation or before it. Two different ways of inputting signal make markable influence on the phase-locking process, this phenomenon is discussed. In this paper, the numerical calculations and analysis are given for gyrotron TE13 mode.

关键词： Microwave oscillator Gyrotron Self-consistent nonlinear theory Phase-locking Stabilized frequency

A TECHNIQUE FOR MEASURING THE LINEARITY OF A LINEARLY FREQUENCY-MODULATED SIGNAL

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Journal of electronics(china) 1995年第1期12卷 66-72页

作者：宋景唯 university of electronic science and technology of china Chengdu 610054

A technique for measuring the linearity of a linearly frequency-modulated continuous wave (LFM-CW) signal is presented. It uses a delay-line and a mixer to sense the slope of the output of a sweep oscillator, so that the original form of frequency function deviated from idealized linear slope is retrieved by means of spectrum analysis. Consequently,the linearity of the LFM signal is determined. The formulation is performed based on the principle that an angle-modulated signal can be approximated by an amplitude-modulated signal if the modulation coefficient is sufficiently small. To examine the validity of the procedure and to study the effect of each parameter on the accuracy of measurement, a number of computer simulations has been made. The results of simulation show that the error of the measurement is less than 2%.

关键词： Linearity Linearly frequency-modulated continuous wave Frequency deviation function

Structures and Properties of PEDOT Nanotubes Prepared by a Template Synthesis Method

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Journal of Wuhan university of technology(Materials science) 2009年第2期24卷 287-291页

作者：徐建华 State Key Laboratory of electronic Thin Films Integrated Devices School of Optoelectronic Information University of Electronic Science and Technology of China

PEDOT nanotubes were prepared by a template synthesis method. Based on our template, it was deduced that there are two successive processes in the formation of nanotubes. The first step is soakage of the porous templates by a polymer solution, and the second step is adsorption of free charged cationic groups and doped PEDOT onto the template surface with negative charges. XRD results showed that well orientated PEDOT chains were formed during the synthesis, moreover the arrange conductivity of molecular chains strongly affect the structures of PEDOT nanotubes. The nanotubes were measured to be about 5.5-17.6 S/cm, which is higher than that of nanotube pellet due to the high contact resistance between the adjacent nanotubes.

关键词： PEDOT nanotube template synthesis method structure property

Three-Dimensional and Cross-sectional Characteristics of Normal Grain Growth Based on Monte Carlo Simulation

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International Journal of Minerals,Metallurgy and Materials 1998年第3期12卷 129-133,139页

作者： Xiaoyan Song Guoquan Liu(Material science and engineering school, university of science and technology Beijing, Beijing 100083, china)(Department of Materials science and engineering, Hebei university of technology, Tianjin 300130, china) Material science and engineering school University of Science and Technology Beijing Beijing 100083 China Departments of Materials science and engineering Hebei University of Technology Tianjin 300130 China

An appropriate Monte Carlo method was developed to simulate the three-dimensional normal grain growth more completely. Comparative investigation on the three-dimensional and the cross-sectional characteristics of normal grain growth was done. It was found that the time exponent of grain growth determined from cross-section exhibits the same rule of increasing slowly with time and approaching the theoretical value n = 0.5 of steadygrain growth as the three-dimensional (3-D) system. From change of the number of grains per unit area with timemeasured in cross-section, the state of 3-D normal grain growth may be predicted. The gtain size distribution incross-section is different from that in 3-D system and can not express the evolution characteristic of the 3-D distribution. Furthermore, there exists statistical connection between the topological parameters in cross-section and thosein three-dimensions.

关键词： Monte Carlo simulation normal grain growth three-dimension cross-section characteristics

Assessment of the apparent activation energies for gas/solid reactions—carbonate decomposition

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Journal of university of science and technology Beijing 2003年第2期10卷 25-29页

作者： Jianhua Liu and Jiayun ZhangMetallurgical engineering school, university of science and technology Beijing, Beijing 100083, china Metall. Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The guidelines for assessing the apparent activation energies of gas/solidreactions have been proposed based on the experimental results from literatures. In CO_2 free inletgas flow, CaCO_3 decomposition between 950 and 1250 K with thin sample layer could be controlled bythe interfacial chemical reaction with apparent activation energy E = (215+-10) KJ/mol and E=(200+-10) kJ/mol at T = 813 to 1020 K, respectively. With relatively thick sample layer between 793and 1273 K, the CaCO_3 decomposition could be controlled by one or more steps involvingself-cooling, nucleation, intrinsic diffusion and heat transfer of gases, and E could vary between147 and 190 kJ/mol. In CO_2 containing inlet gas flow (5 percent-100 percent of CO_2), E wasdetermined to be varied from 949 to 2897 kJ/mol. For SrCO_3 and BaCO_3 decompositions controlled bythe interfacial chemical reaction, E was (213+-15) kJ/mol (1000-1350K) and (305+-15) kJ/mol(1260-1400 K), respectively

关键词： assessment activation energy decomposition carbonate