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    25 September 2005, Volume 33 Issue 9
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    Chaotic Quantitative Calculation via Eigenvector Method and EM I Suppression of Boost Converter
    Zhang Bo Li Hong
    2005, 33(9):  1-5. 
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    As the inherent chaotic behavior of DC-DC converter helps to improve its EMC(Electromagnetic Com.patibility),the quantitative calculation of the chaos is very important.In this paper,the chaotic mapping of DC-DC converter is obtained by first establishing the chaotic model.Then,the eigenvector method is adopted to solve the invariant probability distribution of the chaotic mapping,thus achieving the chaotic quantitative calculation based on the chaotic characteristics.A peak current mode-controlled Boost converter is finally selected as an example for calculating the invariant probability distribution.All the details mentioned above lay a theoretical basis for the sup-pression of EMI(Electromagnetic Interference)of DC-DC converter according to the chaotic characteristics．

    Adaptive M ulti-Fault Diagnosis of Power System Based on GRNN
    Liao Zhi-wei Ye Qing-hua Wang Gang Wen Fu-shuan
    2005, 33(9):  6-9. 
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    In order to realize fast and correct fault diagnosis in electric network,this paper presents a novel fault diagnosis model employing the abilities of GRNN(General Regression Neural Network)in approximation,classifi-cation and learning.Simulated results demonstrate that the proposed model not only can make fast and accurate di-agn oses with good fault.toleran ce performance,but also possesses excellent self-adaptive ability for various topologi-cal structures of electric network.

    Vector-Quantized Fast Codeword Search Algorithm Based on W avelet Transform
    Shi Min Xie Sheng-li
    2005, 33(9):  10-14. 
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    An adaptive fast search algorithm for codewords is presented based on the wavelet transform ,with the aim of overcoming the encoding complexity in the vector quantization(VQ)process.In the proposed algorithm,the squared Euclidean distance is used as the distortion measure of the quantization,and a rational initial matched codeword is chosen for the input vector.The triangle inequalities with multiple control vectors and the characteris-tics 0f the vectors in the transform domain are then utilized to reject non-matched codewords．The best-matched codeword is finally obtained by gradually reducing the search space.Simulated results show that,with little pre-cal-culation and memory cost,the proposed algorithm can significantly reduce the computational complexity of VQ en-coding,and the quality of the encoded image approaches to that obtained by the full search algorithm.

    Development and IP Verification of Control Software of IP Design-Simulation Platform
    Zheng Xue-ren Chen Guo-hui Deng Wan-ling Yao Ruo-he Chen Ling-jing Fan Jian-min
    2005, 33(9):  15-19. 
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    On the basis of the brief introduction of the basic framework and hardware structure Ot the PCI bus-based IP(Intellectual Property)design-verification platform,this paper discusses the basic method of developing the WDM (Windows Driver Model)drivers and applications of the platform in Windows 2000/XP.The proposed key technologies-configuration registers,memory and I/O read-write,as well as application programming are then ana-lyzed.With the IP-verification examples,such as PDMA(Programmable Direct Memory  Access)and picture bina-rization,it is concluded that the proposed platform is better than norm al simulation-verification platform s in which no enough testing data and no final results can be obtained,with a greatly increased eficiency of IP verification.

    A Security Mechanism for Internet-Based Synchronous Collaborative CAD/CAM System
    Liu Wei-we Zhou Lai-shu Zhuang Hai-jun Yuan yuan
    2005, 33(9):  20-24. 
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    The architecture of a synchronous collaborative CAD/CAM system C-Superm an is first introduced in this paper.Next,by analyzing the latent security threats and the running requirements of C-Superm an,a security mechanism for this kind of system is presented.Then,a four-tier security reference model for the synchronous col-laborative CAD/CAM system is constructed. Moreover,according to the security process model of C-Superman,SHA-1 hash algorithm is used twice for the identity authentication,and the transport security of data is finally im-Dlemented by using a mixed encryption method of AES and RSA,giving consideration to the synchronization of the collaborative conversation.

    Chinese Quedtion Classification Based on Support Vector Machine
    2005, 33(9):  25-29,34. 
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    At present,Chinese question classification is commonly based on the combinatorial rules between the in-terrogatives and their interrelated words.Because the extraction of the combinatorial rules gready depends on language knowledge and not all combinatorial rules can be listed.the classification performance is not desirable.As the SVM (Support Vector Machine),a machine learning method based on the statistical theory,possesses excellent discriminating effect on small sample classification,this paper establishes a question classification model based on SVM after the analysis and definition of Chinese question types.Th e process of the feature selection for question classification is then described in detail.Finally,a question classification experiment is carried out by introducing coresponding semantic features based on syntactic achieved,which a classification accuracy of 88.7% being achieved,which indicates that Chinese questions can be excellently clsssified by means of SVM with the combina-tion of syntactic features and semantic features.

    Paramter Identification of "Equal Energy for Equal Mass "Model in the Control of Lithopone Rotary Kiln
    Mao Zong-yuan Li Qi Mo Hong-qiang Wu Jian-ping
    2005, 33(9):  30-34. 
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    In order to overcome the dificulty in the estimation of material amount and the parameter identification ofthe“equal mass equal energy”model proposed in the project of lithopone rotary kiln control,a new method of calculating material amount and identifying parameters is put forward based on the analyses of a large number of historical data and manual experience of workers.In the utilization of this method.the control of material amount iS brought into the control of ACC(Ability of Clearing Color),and the ACC estimated by the workers are used as the basis of the parameter identification.Moreover,the process of parameter identification is presented in detail,and the control effect is finally discussed.The proposed method is successfully applied、to the control of rotary kiln,with the yields and ACC of lithopone improved.

    Coordinated Fuzzy Logic Control of M ultiple Sections on Freeway
    Liang Xin-rong Liu Zhi-yong Xu Jian-min Mao Zong-yuan
    2005, 33(9):  35-40. 
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    In this paper,the hierarchical structure and the fuzzy control are adopted to solve the coordinated control of multiple sections on freeway.A finite-difference model of macroscopic traffic flow is first established.A multilayer control structure is then proposed according to the characteristics of traffic systems.In this structure,the control problems of freeway traffic systems are divided into three layers,that is,an adaptation layer,a coordination layer and a direct control layer.The direct control layer is in charge of the ramp metering rate via fuzzy control,the coordination layer determines the desired traffic density for the direct control layer,and the adaptation layer answers for the selection of traffic models and the adjustment of model parameters according to the real·time freeway traffic status.Simulated results show that the coordinated fuzzy logic control is of good dynamic and steady-state perfor-mance.This method can efectively eliminate traffic jams and maintain stability of main traffic flows.

    Description and Guidance M odel Design of Public Transportation Networks
    Zou Liang Xu Jian-min
    2005, 33(9):  41-44. 
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    In the public transportation networks described by the traditional methods,there is more than one link in the same direction between two nodes.So no way can be adopted to solve the shortest path problem in public trans.portation networks.To solve this problem,this paper brings forward a new description of public tran sportation net· works,by which all classic algorithms for the shortest path problem can be applied to the public transportation gui-dance system.Moreover,three single.objective and a multi·objective public transportation guidance models based on this description are proposed to satisfy different passengers.The effectiveness of the proposed description and models are then proved,and the proposed models are finally implemented in the public networks of Guangzhou,in-dicating that the proposed description and models are very efective.

    Application of Dual·Frequency Tuned M ass Damper to Bufeting Control of Bridges
    Zeng Xian-Wu Han Da-jia
    2005, 33(9):  45-50. 
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    DTMD(Dual-Frequency Tuned Mass Damper)is a new-type tuned mass damper(TMD)with dual fre-quencies.Compared with the conventional TMD,it can simultaneously control the vertical and torsional vibrations of the bridge deck.In this paper,the buffeting differential equations governing the motion of the bridge with DTMD are established based on the multi-mode coupled buffeting theory.Multi-mode participation and aerodynamic COU-piing among modes are all taken into account in the formulation.The random vibration theory is then used to solve the bufeting diferential equations of the system.Finally,parametric studies on a cable-stayed bridge are perform ed to investigate the effects of the frequency and the damping ratio on the reducing efficiency,and the dual-reduction characteristics of the DTMD for bridge bufeting control are also discussed.The results show that DTMD has higher reduction eficiency than the conventional TMD.

    Singular Spectrum Analysis-Based Prediction of Bearing Temperature Trend and Its Application
    Han Feng-qin Gui Zhong-hua Kubota Takashi
    2005, 33(9):  51-54,72. 
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    The SSA(Singular Spectrum Analysis)was used to reconstruct the temperature signals of bearings in the phase space.According to the singular spectrum characteristic of the reconstructed attractor track matrix.the tempe rature signals were separated into two independent components:the trend and the noise. The trendfeature of bearing temperature was then obtained from the original signal.On this basis,a fault prediction sys-tem for the bearing of hydroelectric generating set was developed.This system includes three subsystems respe c-tively for data collection,trend prediction and fault diagnosis.Test results show that the proposed system can predict the increase trend of bearing temperature early,extract the fault characteristics contained by the original signal,give an advance warning to prevent the faults at the burning tile,and can be applied to the state analy-sis,state assessment and fault prediction of hydroelectric generating sets.

    Applieation of 3 D Nonlinear Finite Element Method to the Analysis of Radial Tires
    Ding Jian-ping Jia De-min Huang Xiao-qing
    2005, 33(9):  55-58. 
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    MSC.Marc iS used to the 3D nonlinear finite element analysis of the 205/55ZR16 radial tire,by taking into account the material properties and the structural characteristics of the radial tire.the friction contact conditions between the bead and the rim.as well as the friction contact between the tire and the ground.A comparison between the results obtained by the finite element method and by measurements iS then carried out,considering the
    size of tire contour.the curve of load.deflection,the contact patch and contact pressure between the tire and the ground.It iS found that the results obtained by the finite element method and measurements accord well with each other.Furthermore.the stress.strain of the belt and the bead is analysed,thus concluding that the stress distribution is basically in agreement with the practical one.

    Fast Sintering of Iron-Based Powders with Constant Electric Current
    Long Yan Li Yuan-yuan Li Xiao-giang Wang Jun-Wen Xia Wei
    2005, 33(9):  59-62. 
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    Iron·based mixed powders were fast consolidated via the sintering with constant electric current.To in-vestigate the sintering behavior of the powders,the microstructure and fracture surface morphology of the samples sintered at various durations were analyzed,and the electrical resistance,density and mechanical properties of the samples were measured.It is found that the formation of sintering necks and the diflusion of carbon into the iion matrix occur at a relatively low experimental temperature.In addition,some molten metal can be seen on the patti-cle interfaces,which means that a local high-temperature region is generated in the particle contacting regions at the earlier sintering stage.With the development of the sintering process,the density,transverse rupture strength and microhardness of the sintered sam ple increase,while the electrical resistance gradually decreases.

    Variation of Sintering Stress in Si/Mo Structure with Sintering Temperature
    Han Jing Zhao Shou-nan
    2005, 33(9):  63-66,81. 
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    A new method was first proposed to realize the low-temperature sinterlng of Si//Mo structure.Then,according to the theories of thermoelasticity and interlaminar stress of composites,the interlaminar stresses of the Si/Mo structure at diferent sintering temperatures were analyzed.Moreover,the stress distribution in the Si wafer was measured by using a infrared photoelastic system.Experimental results indicate that the stress distribution
    varies with the sintering temperature,and that the stress decreases with the sintering temperature.By the comparison between the experimental and theoretical results,good consistency is obtained,thus verifying the correctness of the theoretical analyses.

    Preparation and Characterization of TiO2 on Surface of Alumina-Anode Oxidation Film
    Zhang Xin-yu Chen Tie-qun Wang Chun-yan
    2005, 33(9):  67-72. 
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    Titanium dioxide film was prepared on the surface of alumina-an ode oxidation film via AC electrodeposition in the solution of titan ic salt.The structure,morphology,the element composition and its distribution on the surface of the compo site film were then analyzed by means of XRD,OM,SEM EDS and XPS.Moreover,the photocatalytic activity of the film Was analyzed by the photodegradation of methyl oran ge solution under the illumination of UV lights.Th e results show that:(1)the composite film is mainly amorphous and contains a few mixed crystals of anatase and futile,(2)the elements on the surface are mainly AI,O and Ti,(3)during the electrodepostion,alumina partially dissolves and

    Screening and Adsorptivity to Cr(VI)of Aspe Fumisynnematus Strain HLS-6
    Hu yong-you Liu Tie-mei
    2005, 33(9):  73-76. 
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    One Aspergillus fumisynnematus strain HLS-6 with excellent adsorptive efficiency to the heavy metal Cr(VI)was screened from the sludge in a certain cloacae by means of enrichment cultivation.The influence of pH,temperature and initial mass concentration of Cr(VI)on the adsorption of Cr(VI)by HLS-6 was then investi-gated,with the results shown below:(1)theadsorptive efficiency achieves 96.7% at 25～30℃when the pH value is 1～2,(2)with the increase in initial mass concentration of Cr(VI),the adsorptive capacity increases, while the adsorptive efficiency decreases,(3)when the initial mass concentration ofCr(VI)is 9.42 or91.7mg/L,the adsorptive efficiency reaches 100% or 50.8% in 48h,and the adsorptive capacity reaches 4.9 or 23.3 mg/g,and(4)with a strain age of 3～5 d,HLS-6 is of the greatest adsorptive eficiency for Cr(VI).

    Optimization of Hydrogen Gas-Adsorption Drying Process Condition on M olecular Sieves
    Zhu Dong-sheng Peng De-qi Fan Zhong-lei He Lu Zeng Li-ding
    2005, 33(9):  77-81. 
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    The adsorption capacity of molecular sieves is related to many factors.Th is paper experimentally investi-gates the influences of superficial velocity,the thermal boundary conditions and the vacuum desorption time on the adsorption capacity.The results show that:(1)the superficial velocity basically does not affect the total adsorption capacity in the range of the experiment but somewhat greatly afects the adsorption capacity in a unit of time, (2)
    compared with that in natural convection condition.the adsorption capacity would increase by 95% with the heat-insulating measures outside the adsorbent bed,and(3)the adsorption capacity is somewhat greatly affected by the vacuum desorption time,with a desirable time period of 5 h.

    Scale Prevention M echanism in Synergistic Action of Ultrasonic Field and Electrostatic Field
    Lu Hai-qin Qiu Tai-qiu Liu Xiao-yan Yang Ri-fu
    2005, 33(9):  82-86,96. 
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    Simulated evaporation experiments were carried out by using a self-designed scale-preveniing apparatus with the synergistic action of ultrasonic field and electrostatic field.The orthogonal experiment result shows that ex-cellent synergistic effect can be obtained when the ultrasonic field intensity and the electrostatic field intensity are respectively 0.53 W/cm2and 32 kV/m,and an inhibition rate of 78.46% is achieved.The results of iodine release
    experiment show that the ultrasonic cavitation is enhanced by electrostatic field,and that the microscopic energy caused by the ultrasonic cavitation is absorbed by the supersaturated solution in the action of ultrasonic field.Thus,the induction period of CaCO3 crystal is shortened and the nucleation rate is accelerated,which makes the crystals become stable in the form of aragonite suspending but not depositing in the solution,that is to say,the scale is effectively prevented.

    Preparation and Characterizati0n of M ixture of Waterborne Acrylic Resin and HDI Biuret
    Zhou Xin-hua Tu Wei-ping Hu Jian-qing
    2005, 33(9):  87-90. 
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    A kind of two-component waterborne polyurethane(2K-WPU)was prepared by mixing HDI biuret and water.soluble acrylic resin.a dilution with water being followed.The influences of the mixture viscosity and the way of adding HDI biuret during the dilution on the properties of 2K-W PU,which was then characterized by particle size-testing instrument.TEM and rI'IR,were also investigated.The results indicate that:(1)the phase inversion 0f 2K-WPU OCCUrs at a solid content of the mixture of 45%(mass fraction).(2)if added before the phase inver.sion point of waterborne acrylic resin.HDI biuret will disperses in water.achieving a stable 2K-WPU emulsion.(3)according to the TEM results,2K-WPU particles possess the core.shell structure,in which HDI biuret is en.capsulated by waterborne acrylic resin,(4)the 2K-WPU emulsion with HDI biuret is of larger particle size and narrower particle distribution than the acrylic resin emulsion,while the 2 K-WPU emulsion with HDI isocyanurate trimer possesses not only a larger particle size but also a double-peak particle distribution，and(5)according to the FTrIR results．the curing reaction between HDI biuret and warerborne acrylic resin completes in 1 2 h．

    Micro-Econometric Analysis of Educational Quality and the Return Rate from China Education
    Ren Zhao-zhang Fan Min
    2005, 33(9):  91-96. 
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    Micro-econometric methods are used to estimate the individual return rate from China education.In the estimation,the inconsistency between the results estimated by the ordinal least square method and by the conven-tional instrument variable estimator is verified,on the basis of the selection bias and the heterogeneity of samples.Moreover,by using Heckman selection model considering the sample selection bias and the heterogeneity,this pa-per introduces a new “famous university effect” variable to show the effect of educational quality on the wages of graduated students.The result suggests that,compared with those in 1990’s,the return rate from China education in the labor markets of China is greatly improved at present.

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