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Table of Content

    25 October 2006, Volume 34 Issue 10
    Materials Science & Technology
    Ge Hua-ca Ma Zhi-min Zheng Da-feng Ge Jun-wei
    2006, 34(10):  40-43. 
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    A cross.linked chitosan vanillin Schif base was synthesized by formaldehyde under microwave radiation,whose structure was then characterized by means of IR and XRD.The solubility of the product·in acidic solutions was also compared with that of chitosan vanillin Schif base using UV absorption spectrum.The adsorption experi-ment showed that.as compared with chitosan vanillin schif base and cross.linked chitosan by form aldehyde,the
    product is of different adsorption capability for some metal ions.Moreover.as the product possesses excellent selec-tive adsorption for Cu2+ and is insoluble in acid conditions.it can be used as a selective adsorbent of Cu2+ .

    Cai Yong-hong Qu fin-ping
    2006, 34(10):  44-49. 
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    An approxi‘mate analytical model describing the melt conveying under the effect of single screw vibration was established by using the self-modified Tanner constructive model.and the coefficient reflecting the effect of vi-bration force field on the apparent viscosity of the melt was formulated according to the theory of equal viscosity dis-sipation energy.Experiments were then carried out to reveal the effect of vibration force field on the melt conveying
    in an extruder with single screw vibration,and to reveal the head pressure and the screw characteristics varying with the vibration frequency and amplitude.The results of theoretical analysis and experimental investigation indicate that the melt conveying under the effect of single screw vibration can be performed in low pressure,which may also result in the softening of the screw.

    Li Tian zeng Xing-rong
    2006, 34(10):  50-54. 
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    Flame retardant polypropylene(PP)was prepared with ep0xy/0rgan0phi1ic montorillonite(Epoxy/OM-MT)nanocomposite and triphenyl phosphate(TPP)mixture as the flame-retardant agents.The effects of the sort ofepoxy ,the mass ratio of OMMT to epoxy and the contents of Epoxy/OMMT and TPP on the properties of PP were then investigated.The structure of the production was finally characterized by XRD.The results show that there is a good synergistic flame-retardant effect of((NER)/OMMT)and TPP on PP,and that,when the mass ratio of OMMT to NER is 5:100 and the mass fractions of NER/OMMT and TPP are respectively 13.33%and 6.67% .the oxygen index of the prepared flame retardant PP reaches 36.5% .

    Zeng Neng Chen Yu-kun Wang Wan-Xun Jia Zhi-xin Jia De-min Li Zong-bao Yang Di-lun
    2006, 34(10):  55-57,61. 
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    SEM ,XRD,elementary analysis and FTIR were adopted to characterize the loose nano magnesium hy-droxide(LN-MH,followed by the measurement of particle diameter.Experimental results show that(1)the ratio of MH to oleatc ions of LN-MH is 9.386 to 1 in the number of molecule;(2)the LN-MH crystal is lamellar,with at least one nano.scaled dimension in 3 D space;(3)there is a tight chemical combination between COO-of the coating agent and the nano particles;and(4)the diffraction intensity of 00 1 plane of the nano crystal with weak polarity obviously increases.while the corresponding polarity decreases.

    2006, 34(10):  58-61. 
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    The finite element analysis(FEA)of the interfacial stress distribution during the tension of CaCO3-filled polypropylene(PP)composite was carried out using the ANSYS software.The results of the 3D simulation were then compared with those of the 2D simulation.It is thus concluded that the shear effect subjected to the pole zone of CaCO3 particles is maximal,and the tensile stress reaches the maximum in the equator zone because of the strong pressing and pulling due to the resin matrix.Moreover,the 3 D stress distribution is more undulant than the 2 D one.

    Che Chun-shan Lu Jin-tang Xu Qiao-yu Kong Gang Sui Run-zhou
    2006, 34(10):  62-66. 
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    Five kinds of steels respectively with the Si contents of 0.04% ,0.09% ,0.14% ,0.28% and 0.36% were electrodeposited with iron layer and were then galvanized in molten Zn.The corresponding formation and growth of the Fe-Zn interm etallic compound layer were investigated.The results show that the Fe-electrodeposited pretreatment can obviously restrain the quick growth of the galvanized coating of reactive steel,and that eligible coatings can be obtained when such reactive steels as Sandelin steel,thin hyper-Sandelin steel and Sandelin steel with a Si content about 0.28% are electroplated with an iron layer less than 10μm before being immersed in zinc bath.EPMA(Electron Prob Micro Analysis)results show that(1)excessive silicon in the steel accumulates on the surface of the steel substrate;and(2)with the movement of the steel/galvanized coating interface towards the steel substrate,the silicon-rich a-Fe peels of from the substrate and breaks into particles.The particles.much like the inert marker in Kirkendall effect experiment,enter the δ layer through the G layer,thus accelerating the growth of the δ layer towards the Γ layer till to a disappearance of the G layer.Moreover.the iron-electrodeposited pretreat.ment postpones and weakens the influence of silicon on the galvanized coating,so that the quick growth of the galvanized coating can be inhibited in a certain galvanizing time that increases with the thickness of the iron-electrode-posited layer.

    Power & Electrical Engineering
    Lin Yu-zhang Cai Ze-xiang Zhu Hao-jun
    2006, 34(10):  67-72. 
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    An AC/DC power system with three DC links is presented for the investigation of DC damping control.The presented system is of complicated grid structure and multiple oscillatory modes,which extensively exist in practical AC/DC power systems and must be given enough consideration in DC damping controller design. By means of the modal analysis and the transient simulation.the performances of the system are then analyzed.Moreo-ver,multiple DC damping controllers are designed based on the proposed power transmission system.The analysis of root lOCUS shows that the frequency differences across DC links are superior to the active power deviations on AC tie lines in the phase compensation design,so that they can be selected as the input signals into DC damping con-trollers.Furtherm ore,the results of transient simulation demonstrate that the designed DC damping controllers effectively improve the damping of the power transmission system.

    Xie Yun-xiang Qiu Tian-quan
    2006, 34(10):  73-76. 
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    A novel inverter based on the Buck conversion iS presented.Then,a low-frequency mean-value model of the inverter circuit is established to analyze the steady and transient responses of the converter with different classic control methods by means of the classic control theory.The best control method named PD control is finallv achieved.Experimental results show that the presented inverter is of good transient response and robustness, thus validating the correctness of theoretical analysis.

    Cai Li-juan Hu De-cheng Liu Yong-Gang
    2006, 34(10):  77-82. 
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    The stability of Boost converter is analyzed based on the differential dynamic theory and the state-space.average model,with the feedback parameters kl and k,as the bifurcation variables.Several unstable behaviors and the corresponding stability criteria are thus revealed.The results indicate that.when the duty radio of the converter is salurated,the converter is open-looped,with an unstable output voltage due to the load variation,and that when the duty radio is unsaturated and the modelis nonlinear.the eigenvalues of Jacobian matrix.which result in the stable or unstable behaviors of the system,are the functions of system parameters.A qualitative analysis of the relationship between system parameters and the stability is finally carried out,the corectness of which is verified by Matlab simulation.

    Zhu Hao-jun Cai Ze-xiang Liu Hao-ming Ni Yi-xin
    2006, 34(10):  83-88. 
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    In order to improve the accuracy of the traditional simulation model of HVDC (High-Voltage Direct Cur-rent Transmission)system,a novel hybrid-model simulation algorithm is proposed to analyze the transient stability of AC/DC system,in which the dynamic phasor theory and the traditional electro-mechanical transient models are respectively applied to the modeling of HVDC and AC systems.An iterative algorithm for the interface between the HVDC dynamic phasor model and the AC system is then investigated by hybrid simulation.It is then concluded that,as compared with the electromagnetic transient model,the HVDC dynamic phasor model is of higher accura-cy,and that the proposed interface algorithm can be effectively adopted to analyze the transient stability of AC/DC system.

    Zong Xiu-hong Zhang Yao Wu Zhi-gang Zhang Zhi-chao
    2006, 34(10):  89-93. 
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    The power limit(or voltage stability margin)serves as an important index to describe the static voltage stability of power system.As the conventional method to calculate the nearest power critical point(or the minimum voltage stability margin)is based on a single system-operating state,the obtained results tend to be optimistic.In this paper,multiple system-operating conditions in a system period in the probabilistic environment are considered
    by inserting the probabilistic characteristics(the mean values and the covariance)of nodal voltages and nodal powers into power flow equations.The minimum voltage stability margin of the system in multiple operating conditions is computed accordingly,and the corresponding margin distribution with a normal probability is finally calculated.

    Cai Jie-fin Ma Xiao-qian
    2006, 34(10):  94-99. 
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    In order to solve the unit commitment problem,a new fuzzy genetic algorithm that closely combines the fuzzy optimization and the genetic algorithm is proposed.Then,some fuzzy inference rules are established to control the crossover rate and the mutation rate,thus improving the convergence speed and avoiding the premature conver-gence.The proposed fuzzy genetic algorithm is finally adopted to solve the unit commitment problem in a practical
    case.The results show that,as compared with the traditional genetic algorithm,in the same population scale and termination criteria,the convergence iterative times of the proposed algorithm decrease even by 1 22,while the com-putation time cost per population only increases by about 0.01s.Moreover.the electricity-generating cost with the optimal unit commitment decreases,with the largest contraction up to 0.73%of the corresponding total operation cost.

    Lou Bo Cai Rui-xian
    2006, 34(10):  100-104. 
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    Waste disposal is one of the noticeable problems of urban environment protection.In this paper,three kinds of popular waste disposal methods,namely,the waste composting, the landfill gas-generated electricity and the waste incineration-generated electricity,are analyzed.The results show that all these three methods obtain negative net incomes based on the cost-benefit analysis,and the waste composting is of the lowest cost.After intro-ducing the Clean Development Mechanism(CDM)and acquiring the incremental cost fund from Annex I countries,both the landfill gas-generated electricity and the waste incineration-generated electricity obtain positive net in-comes,especially the former.Moreover,it is concluded that the landfill gas-generated electricity has an extended worthiness and a good investment refund because it possesses a net income of 9.1 8yuan per ton waste,and an incre-mental cost of 253.0 yuan per ton CO2.

    Chemistry,Chemical & Energy Engineering
    Zhong Li Luo Jing Li Chuang Karl
    2006, 34(10):  1-5. 
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    This paper investigates the anode and cathode catalysts for an intermediate·temperature proton-conducting membrane H2S fuel cell based on the requirements of three·phase boundary theory.By investigating the perform ances and chemical stabilities of three anode catalysts,namely,Pt,MoS2 and composite metal sulfide(MoS2/NiS)in the condition of electrochemical oxidation of hydrogen sulfide,it is indicated that MoS2 and MoS2+NiS exhibit better cata-lytic activity than Pt,and that,at a temperature more than 450℃,MoS2 itself sublimes, while the composite cata-lyst MoS2/NiS containing both Mo and transition metal Ni remains stable.Moreover,by the research on the electro-chemical performances of two cathode catalysts such as Pt and composite NiO,it is shown that(1)composite NiO is of lower over—potential and better electrochemical performance;and(2)the poor electrical conductivity of com-posite electrodes(anode or cathode)can be overcome by admixing Ag powder into the catalyst layer with a dosage of 10% by weight.Finally,by the investigation into the electrochemical perform ance of the fuel cell made of H2S,(MoS2+NiS+Ag+electrolyte+starch)/Li2SO4-Al2O3/(NiO+Ag+electrolyte+starch),air at 101.13 kPa and 600~680℃,it is revealed that the highest delivered current,power densities of the cell can reach 240 mA/cm2 and 70 mW/cm2 at 680℃,respectively.

    Jian Qi-fei Zhao yYong-li Liu Hai-yan
    2006, 34(10):  6-10. 
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    In order to study the effects of working parameters such as the working temperature and the pressure of reactive gases on the output performance of Proton Exchange Membrane Fuel Cell(PEMFC),an electrochemical model and a working parameter model of the cell were established.Then,by taking the Mark V fuel cell engine as an example.the variation of the output performance with the working temperature and the pressure of reactive gases
    was simulated with Matlab software.The results show that(1)the mean cell power and voltage increases by 3%for each temperature increment of 10 K,with a slightly decreasing increment in high-temperature conditions;(2)the output perform ance of the cell can be improved by increasing the gas pressure,but the amplitude is limited by the fuel cell whose feasible working pressure is generally not more than 1 MPa;and(3)PEMFC possesses excellent in-stantaneous overloading ability.

    Shen Hui Liu Xi-Yun
    2006, 34(10):  11-14. 
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    In the production of monocrystalline silicon solar cells.alkaline solution is CUstomarily used to texture the cell surface,which makes the surface to trap light as well as increases the absorption of lights. BesideS.textu.ring“pyramid”can be formed on the silicon surface due to the difference in etching ratio.Such fact0rs as the alka.line solution content,the additive dosage,the reaction temperature and the etching time all have certain effects on the:formation of the“pyramid”.In this paper, the effects of the above.mentioned factors affecting the form ation of"pyramid”were analyzed by orthogonal experiments.and the optimal conditions for texturing“pyramid”were ob.tained.It is found that the optimal experimental conditions include an alkaline solution COncentrati0n of 2.5%.a reaction temperature of 95 ℃,an additive dosage of 5%and an etching time of 30 min.

    Peng Shao-hong Chert Lie-qiang Cai Ming-zhao
    2006, 34(10):  15-19,24. 
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    The characteristics of HBr form ing and scavenging during the pyrolysis of waste printed circuit boards were investigated using the TG-FTrIR and a qua~z-pipe pyrolysis system.The results indicate that(1)HBr is main. ly released at the fast weight-losing stage(300 to 360℃)of printed circuit boards,accompanying with the main chain scissions of epoxy and brominated epoxy backbones;(2)HBr can be eficiently scavenged by adding calcium
    carbonate,which has no negative effect on the degradation behavior of printed circuit boards;and(3)the harm of HBr can be completely eliminated by selecting the amount and diameter of the added ca1cium carb0nate as well as by controlling the heating rate and the pyrolysis temperatur

    Xia Jie Chang Hai-ping
    2006, 34(10):  20-24. 
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    The thermally driven heat transfer phenomena in four small-size circular channels in the gravitation field were compared by numerical simulation.In the investigation.the four channels were all heated at one end and cooled at the other,and the therm al driving of fluid is used to accomplish the heat transfer in a high body-force field.The results indicate that the four circular channels all follow the same law of thermally driven heat transfer.and that the ability of thermally driven heat transfer improves with the increase in the number of the circular chan.nels.It is thus concluded that,when utilizing small-size circular channels for the cooling of turbo vanes. the multi.cyclic channel may be feasible because the adaptability of fluid can be utilized to enhance the heat transfor

    Guo Ping-sheng Han Guang-ze Hua Ben
    2006, 34(10):  25-29,34. 
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    A phase equilibrium equation describing the Langmuir adsorption in external physical fields is established based on the theory of molecular dynamics.According to the forced vibration of the molecules in the adsorp.tion Dhase and the fluctuation of the molecules in the fluid phase within an ultrasonic field,the energies obtained by the naolecules in both the adsorption phase and the fluid phase ale then investigated.The results indicate that the decline of Langmuir adsorption isotherm is due to the greater energy obtained by the molecules in the adsorption Dhase.Furtherm ore.the theoretical analysis show that,when the ultrasonic frequency remains constant,the ad.sorbed amount in Langmuir adsorption phase equilibrium decreases with the increase in ultrasonic energy flow,and that when the ultrasonic energy flow remains constant,the molecules in the mum energy by regulating the ultrasonic adsorbed amount in Langmuir adsorption adsorp frequency to the natural frequency of the phase equilibrium.tion phase can obtain the maxi-molecules,thus minimizing the adsorbed amount in Langmuir adsorption phase equilibrium.

    Wang Ke-jun Liu Fang Zhou Xiao-lian Jia De-min
    2006, 34(10):  30-34. 
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    Hexadecyl acrylate was prepared by the microwave-assisted direct melting esterification,with acryI.acid and hexadecyl alcohol as the raw materials and toluene-P-sulfonic acid as the catalyst.The efects of the microwave power,the irradiation time,the molar ratio of acrylic acid to hexadecyl alcohol and the catalyst dosage on the vield weIe then investigated.The results show that,in the optimum conditions of preparing hexadecyl acrylate,a
    micr0wave power of 260 W ,an irradiation time of 1 5 min,a molar ratio of acrylic acid to hexadecyl alcohol of 1.3:1.0 and a catalyst dosage of 0.7%,the yield of hexadecyl acrylate reaches 97.5%and the reaction rate in.crefitses by 16 times.All these reveal the superiority of microwave-assisted synthesis in terms of technological effi-ciency and energY cost.A new method to synthesize hexadecyl acrylate is thus provided.

    Huang Dong-gen Liao Shi-jun Dang Zhi Yang Jie Guo Wei
    2006, 34(10):  35-39,49. 
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    Fluorine-doped anatase TiO2(F-TiO2)sol was prepared by means of the sol-gel-hydrothermal crystallization method with tetrabutyl titanate as the precursor.A photocatalytic film.coated fluorescent lamp with good formal-dehyde-degrading ability was then fabricated by coating F-TiO2 sol on the surface of a common fluorescent lamp and drying the film at 1 20 to 280℃ .and the photocatalytic refining activity of the lamp was evaluated by using the air containing form aldehyde as the simulated contaminated air.Moreover,the adsorption perform ances of the dried F-TiO2,sol particles were measured.and UV-Vis-Diffuse Reflectance Spectroscopy(UV-Vis-DRS)and Atomic Force Microscopy(AFM)were finally adopted to investigate the characteristics of the F-TiO2 film coated on the glass surface.The results indicate that(1)the nano.sized anatase F-TiO2 sol is of good formaldehyde—degrading performance and photocatalytic ability;(2)the degradation rate of formaldehyde is up to 90% when the initial
    rmaldehyde content and the flow rate are respectively less than 5.4 mg/m and 0.015 L/min;(3)the brightness of the catalyst.coated fluorescent lamp is improved by 2%~3% due to the fluorescence of F-TiO2 film;and(4) the doping of F improves the surface acidity,the crystallization degree and the adsorption capability of the photocatalyst,thus effectively enhancing the photocatalytic activity of the F-TiO2 film.

    Physics
    Peng Jun-biao Lan Lin-feng Yang Kai-xia Niu Qiao-li Cao Yong
    2006, 34(10):  105-108,112. 
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    A kind of organic thin.film transistor(OTFT)was fabricated withTa2O5as the gate insulator and poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene)(MEH-PPV)as the active material.The influence of therm al treatment of theTa2O5 gate insulator in H2,atmosphere on the perform ance of OTFT was then discussed,and the re.asons for the perform ance improvement of OTFT were analyzed.The results show that,after the therm al treat-ment of the Ta2O5gate insulator in H2 atmosphere,the field effect mobility of MEH-PPV can be greatly enhanced from 1.24×10-5 cm2 /(V·S)to 2.15×10-4cm 2/(V·S),while the threshold voltage decreases.

    Chen Hui-qing Wang Li-shi Wang Hong Zhang Shui-feng
    2006, 34(10):  109-112. 
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    A microfluidic chip was manufactured with p0lydimethylsil0xane(PDMS)and was sealed with glass by PDMS.attaining a success rate of about 100%.Then,an optical fiber detection system with simple and compact structure was assembled using optical fibers and a photon counter,which was applied to the detection of laser-in-duced fluorescence.The performance of the assembled system was finally tested with argon ion laser as the excited source and with rhodamine B(5×10-6 mol/L)as the detected sample.The results indicate that the system is of distinct fluorescent signal and good repetitive perform ance.

    2006, 34(10):  113-116,122. 
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    In order to overcome the overlapped absorption structures in differential optical absorption spectroscopy(DOAS),a method of spectrum correction based on Kalman filtering is developed.Kalman filtering,a modern re-cumive filtering,can corect disturbed spectrum signals even though the signals are strongly overlapped.This paper introduces DOAS in brief,analyzes the mechanism of Kalman filtering,Kalman filtering is applied to process the
    differential optical absorption spectrum of SO2 in the atmosphere,meanwhile,the influence of NO2 and O3 on SO2 is discussed in this paper.Experimental results indicate that the proposed method can effectively corect overlap-ping spectra and greatly improve the accuracy of DOAS system.

    Chang Tian-hai Yun Jun-xun
    2006, 34(10):  117-122. 
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    Acc0rding to the analytical theory of electrostatic hidden troubles and the practical data gathered in a Railwav Freight Yard for dangerous goods,the electrostatic hidden hazards in the railway freight yard fo r dangerous goods were directly evaluated and analyzed,and two models,namely,the Floating Human Body Model and the Hu-man Body-BaITow Model,ere put forward.Some feasible preventive measures were finally presented in the paper·
    The Dractical data,the resuIts of direct evaluation,mechanism analysis and model analysis all show that there exist serious electrostatic hidden hazards in the railway freight yard for dangerous goods because there lS an obvious state of electrostatic shock to the human body,and there are not only lots of easy-burning or easy-blasting goods but also manv kinds of electrostatic sources in the railway freight yard.The electrostatic discharge energy exceeds the mini-mum igniting energy of most easy-burning goods,thus resulting in the dificulty in the removal of hidden hazards of
    buming and blasting caused by electrostatic discharge.Therefore,more attention should be paid to the protection of electrostatic discharge in the railway freight yard for dangerous goods.

    2006, 34(10):  0. 
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