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    25 January 2006, Volume 34 Issue 1
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    Materials Science & Technology
    Strengthening and Toughening of Dental Porcelain Fused to M etal by Nano-Sized AI2O3
    Yang Jin-ping Lü Ming Xin Chong-fei Peng Cheng Rao Ping-gen Wu Jian-qing
    2006, 34(1):  101-104. 
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    Nano sized AI2O3powders were used as dispersed particles to improve the toughness and strength of low.temperature dental porcelain fused to metal,and XRD was used to determine the phase composition of nano- sized AI2O3in the sintered specimen．The effects of AI2O3content on the strength,hardness and toughness of the sintered specimen were also investigated．Results show that the bending strength,hardness and toughness increase with the content of nano.sized AI2O3,and that adding 1. 5%(mass fraction)of nano-sized AI2O3 into the dental porcelain may remarkably enhance the strength and toughness when the sintering temperature is not higher than 900℃.

    Rheological Behavior of Polypropylene/Organic Montmorillonite Nanocomposite
    Ding Chao Jia De-min He Hui Guo Bao-chun Li Hui yong Yan Li
    2006, 34(1):  105-109. 
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    Polypropylene/organic montmorillonite (PP/OMMT) nanocomposite was prepared by using a solid-phase-grafted PP(TMPP)as the interfacial modifier,whose nanostructure was then observed using transmission electron microscopy(TEM).The influence of TMPP on the dynamic rheological behavior of the nanocomposite and the relationship between the rheological behavior and temperature were also investigated.The results show that the dynamic elastic modulus,loss modulus and complex viscosity of the nanocomposite are higher than those of PP,while the loss factor is lower,that the complex viscosity of the nanocomposites is more sensitive to temperature,and that the flow activation energy and the crystallization temperature increase respectively by 1 5%and 1 0 K as coin-pared with PP,which may contribute to the enhanced interfacial interaction between PP and OMMT resulting from the addition of TMPP.

    Effect of Multicomponent Coagulating Baths on Pervaporation Performance of Chitosan Membrane
    Yah Bing Zhao Yao-ruing Gao Guang
    2006, 34(1):  110-113. 
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    During the formation of the chitosan membrane,there arises the diffusion and exchange of multiple sub-stances,and the combination and decomposition of various ions.In this paper,the effects of these factors were pre-liminarily investigated by using a series of multicomponent coagulating baths,with corresponding mechanisms being also studied.The results show that the difference between the difusion speed and the neutralization speed arising in the alkali bath may result in the variation of the membrane structure homogeneity,and that,at a temperature range
    of 10 to 20 ℃,the ter component coagulating bath(mass ratio of NaOH/ethanol/NaAc is 80/20/0.5)possesses good pervaporation perform ance,and the coresponding membrane is of good stability,improved separation coeffi-cient and permeation flux.

    Experimental Verification of Theoretical Heat-Transfer Model of Polymer/Hollow M icrosphere Composite
    Liang Ji-zhao Li Feng-hua
    2006, 34(1):  114-116. 
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    The effective thermal conductivity(κeff)of hollow microsphere-filled polypropylene(PP)composite was
    measured by using a thermal conductivity instrument，and the equation of efective thermal conductivity published
    in the previous paper was preliminarily verified．The results show that the estimated values of κeffare in good agree—
    ment with the measured ones except few points，and that κeff decreases roughly linearly with the volume fraction(φf)
    of hollow microsphere when φf≤20%，while decreases slightly with the increase in particle diameter at lower φf．

    Electronics, Communication & Automation Technology
    Adaptive Bit-Loading Algorithm in OFDM System
    Gong Han-dong Ye Wu Feng Sui-li Ke Feng
    2006, 34(1):  1-5. 
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    The application of adaptive technique to OFDM (Orthogond Freguency Division Muhiplexing)systems can effectively improve the system performance.In this paper,an adaptive bit-loading algorithm to minimize the transmission power is investigated for the case of fixed data rate and restricted subcarrier bit rate.During the inves-tigation,the optimization of infinitesimal inform ation granularity is first solved to determine the low bound of the minimal power,and then the optimization of integer bit(finite information granularity)is solved,resulting in a fast integer bit-loading algorithm.Simulation results indicate that the proposed algorithm is an optimal bit—loading algo-rithm with high operating speed.

    Improved Blind Separation Algorithm by Adding Momentum Term
    Lin Yong-man Lin Tu-sheng
    2006, 34(1):  6-9. 
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    During the deduction of blind signal separation algorithms,the commonly adopted steepest descent meth-od,natural gradient method and Newton’s method to minimize the contrast function may resuIt in the complexitv of the deduction.So.the momentum term is added in the derivation of the Cross.Cumulant-Zero-Forcing algorithm by imitating the addition of the momentum term in BP neural network to improve the algorithm ,which keeps the inde-pendence of the outputs to the limit,and is of a higher convergence speed than the original algorithm with the same briefness．Moreover．the local minimization in training can be avoided.Simulated results indicate that the proposed algorithm is of little separation error and is helpful to the effective separation of source signal.

    Fast Algorithm for Calculating Call-Blocking Probability Based on FFT in Large-Scale Networks
    Xu Xing Ye Wu Fmg Sui-li Xie Ming
    2006, 34(1):  10-13,34. 
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    In large-scale networks,the 1 D fast recursion CBP(Call-Blocking Probability)algorithm proposed by Kaufman is unavailable due to the data overflow caused by the calculation of CBP.The modified Kaufman method overcomes the trouble of data overflow,but the time consumption exponentially increases with network scale.To get out of this trouble,a fast algorithm to calculate CBP based on the F1 (Fast Fourier Transform)and the pretreatment method is proposed,Simulation resuhs show that the fast algorithm not only avoids data overflow but also decreases computation complexity dramatically,and is of the advantages of simplicity,rapid computation and high accuracy.

    Fast Algorithm of EBCOT Bit-Plane Scanning for Gray Medical Images
    Xu Xiang-min Shu Lin Liu Wei Xing Xiao-fen
    2006, 34(1):  14-17. 
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    Considering the disadvantages of consuming too much time by the bit-plane scanning by EBCOT(Em-bedded Block Coding With Optimized Truncation)encoder of JPEG2000,a fast algorithm of bit-plane scanning isproposed for the progressive transmission of gray medical images based on the characteristics of the three··pass scan-ning.The algorithm generates the iun length query table of column skipping sign in the first pass,thus overcoming the shortcoming of the Group-of-Column Skipping method and realizing the jumping of any length column group.Experimental results show that,compared with the Group-of-Column Skipping method,the proposed method is of higher scanning efficiency,and the time consumption reduces to 94%of that of the Group-of-Column Skipping method.

    A Prediction-based Vector Quantization Method for Image Coding
    Shi Min Xie Sheng-li
    2006, 34(1):  18-23. 
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    In order to improve the efficiency of image coding,a prediction-based vector quantization method is Droposed.Two codebooks with different dimensionalities and sizes are respectively employed at the encoding and the decoding ends.For smooth areas,the input vectors are encoded with small-size codebook to speed up the encoding and reduce the bit-rate.For edge areas,the input vectors are quantized with large-size codebook
    to maintain the image quality.An efficient method for codebook design is also presented to improve the quality of the resulted codebook.Simulated results indicate that,compared with other decoding methods,the proposed method speeds up the encoding and reduces the bit·rate with the image quality keeping unchanged.

    Analysis of Queuing Performance of Self-Similar Trafic Input
    Xie Ming Ye Wu Feng Sui-li Song Hui
    2006, 34(1):  24-28. 
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    As all the traffics whose arrival time interval submits to Pareto distribution have the self-similarity,the queuing behavior of the network system with Pareto distribution inter,·arrival time and negative exponential distribu-tion service time distribution is investigated via the fitting technique of complementary cumulative distribution function and the matrix geometric method.The average queue length and buffer overflow probability of Pareto/M/1/K qu eue are then approxima tely derived.Simulated results are finally presented to verify the accuracy of the proposed method/

    Relationship Between MDCT and Simultaneous M ask Efect Curve
    xie Zhi-wen Yin Jun-Xun
    2006, 34(1):  29-34. 
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    The relati0nship among modified discrete cosine transform(MDCT),discrete Fourier transform (DFr) and simuhaneous mask effect curve is investigated in this paper,concluding that it is impossible to get a MDCT simultaneous mask effect curve being adapted for all sample ratios and transfornl block sizes via experiments or theoretical analyses.because the amplitude and frequency shift of the sinusoidal component represented by XMDcT(k) are related to samp1e ratio and wave number k.Thus,it is necessary to calculate the simultaneous mask threshold by means of DFr in quantifying the MDCT coefficient.

    Theoretical Analysis of Raman Threshold of Fiber Raman Amplifier
    Long Qing-yun Wu Ting-wan Deng Hua-qiu
    2006, 34(1):  35-37,56. 
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    In order to obtain the critical condition of fibre Raman am plifier,an equation describing the threshold power of the am plifier is deduced when considering the energy transfering from pumping-light to signal-light.The maximum fibre loss and the minimum fibre length in critical condition are also calculated.All these above-men tioned results are then compared with the results in literature and the results obtained by recent experiments.indi-caring that the proposed threshold equation is more rigorous.Finally,the optimal pumping power and fibre length are obtained,which can be used for the design of fibre Raman amplifier.

    An IP Simulation and Verification Platform Based on FPGA
    Zheng Xue-ren Deng Wan-ling Fan Jian-ming Chen Ling-ring Chen Guo-hui Lin Xiao-wei
    2006, 34(1):  38-42. 
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    The simulation and hardware verification of IP(Intellectu',d Property)is an indispensable step in IP development.In this paper,an IP simulation and verification platform is developed based on FPGA(Field Pro-grammable Gate Array),and PCI(Peripheral Component Interconnect)bus is used to test IP cores.Thus,a target IP inserted into the platform can be easily tested,The proposed platform is then simulated to verify the functions,and is debugged in a PCI add-on card with Xilinx Spartan-3 600E FPGA.The results show that．on the proposed FPGA-based IP simulation and verification platform,IP can be effectively simulated and verified with good stability,which illustrates the practicability of the platform.

    Control of Dynamic Over-Voltage in Series Connection of IGBT
    Li Yong Shao Cheng
    2006, 34(1):  43-47. 
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    The dynamic over-voltage in the series connection of IGBT(Insulated Gate Bipolar Transistor)of highvoltage and high-power inverter equipment is investigated,and a quick feedback controlling method based on the bang-bang control is presented to control the component voltages of the equipment,with the aim of restraining the dynamic over-voltage of two series components.Moreover,a feasible mutual circuit for feedback signals is pro-posed,according to the characteristics of controlling loops,to offer timely and precise on-of signals for the serial IGBT.The proposed method is finally applied to the frequency-varied control of an AC induction motor.The results indicate that the proposed controlling method meets the practical requirements of great controlling accuracy and high responding speed,and that the designed mutual circuit for feedback signals is of good expansibility．

    PTPD/AIq3 Heterostructure Electroluminescent Diode and Its Stability
    Nie Hai Zhang Bo Tang Xian-zhong Li Yuan-xun
    2006, 34(1):  48-51. 
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    ITO/PTPD/Alq3/Mg:Ag heterostructure electroluminescent diode was fabricated by using a novel poly-TPD as the hole transport material，and its electroluminescent properties was investigated.The results indicate that only the intrinsic emission of PD(poly-TPD)is obtained when Alq3 layer is very thin(not more than 10 nm),and that only the intrinsic emission of Alq3 is obtained when the thickness of Alq3 layer is up to 50 nm.Moreover,the fabricated diode is of an improved stability due to the excellent thermal stability and film quality of PTPD,as, compare with the typical ITO/TPD/Alq3/Mg:Ag device.

    Soft-Sensing Model of Chaos Time Series of Crude Copper Composition in Copper Convertor and Its Application
    E Jia-qiang Wang Yao-nan Gong Jin-ke Li Chun-sheng Mei Chi
    2006, 34(1):  52-56. 
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    A new soft-sensing model of current crude copper composition based on the chaos time series of foregone crude copper composition was established by using the phase-space reconstruction theory and the method of maxi-mum Lyapunov exponent and by updating samples in time.In this soft-sensing model,foregoing assay data of crude copper composition were regarded as the secondary variables,the assay data of crude copper composition in curent copper convertor were taken as the primary variables because of its great delay,and the chaos time series of fore-gone crude copper composition was divided into two sub-series via the time lag τ=2 furnace orders.Experimental results indicate that the crude copper composition in curent copper convertor can be quickly and precisely deter-mined by the proposed soft-sensing model.

    Adaptive Particle Filtration for State Estimation
    Deng Xiao-long Xie Jian-ying Cuo Wei-zhong
    2006, 34(1):  57-61. 
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    This paper analyzes the keys for the performance of particle filter(PF)and presents a new adaptive PF algorithm.The algorithm adopts a new proposal distribution combining the unscented Kalman filter(UKF)with the adaptive strong tracking filter(STF).The new proposal distribution adopts UKF to produce the particles,in which each sigma point of every particle is updated by STF.Moreover,the added scaling factor can be adjusted on line to
    make the algorithm adaptive.Simulated experiments of nonlinear state estimation are finally ca~ied out to confirm the validity of the improved PF algorithm.

    Artificial Immune Algorithm Based on Idiotypic-Network Dynamic Model
    Tan Guang-xing Li Zhong-hua Mao Zong-yuan
    2006, 34(1):  62-65,72. 
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    To overcome the demerits in evaluating the similarity,the concentration and the antibody of the conven.tional artificial immune algorithm ,this paper proposes an improved artificial immune algorithm based on the idioty-pic-network dynamic model by defining the antibody concentration as the fitness.In the proposed algorithm,the in-formation about the function value and the similarity of antibody can be c0mprehensiveJy extracted by modifying the calculation method of afinity.Simulated results show that the improved algorithm is effective on the optimization of multi-mode function and is of better searching eficiency and higher convergence speed than the conventional Opt-aiNet algorithm.

    LM I Approach to Guaranteed Cost Control of Fuzzy Large-Scale Systems with Parametric Uncertainty
    Zhang You-gang Xu Bu-gong Hou Xiao-li
    2006, 34(1):  66-72. 
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    A practical system should possess stability and other performances.This paper describes the guaranteed cost control of interconnected fuzzy large-scale systems with parametric uncertainty and proposes a design scheme of the guaranteed-cost controller with decentralized state feedback via LMI(Linear Matrix Inequality)technology.The proposed controller not only ensures the asymptotic stability of the closed-loop uncertain fuzzy large-scale system but also minimizes the upper bound of the quadratic perform ance measure of the system.A numerical example is finally provided to reveal the validity of the proposed approach.

    Control of Internet-Based TeIe0perati0ns for Robot via Hybrid Dynamic System
    You Lin-ru Wang Qing-yang
    2006, 34(1):  73-76. 
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    During the teleoperation of a robot via Internet,an operator cannot correctly and duly obtain real-time data due to the uncertain time delay in the Internet-based communication,So the state of a robot cannot be efec-tively controlled.To get out of the trouble,this paper is oncentrated on the modeling and control of Internet.based teleoperation system of robot by using the hybrid dynamic system approach,and proposes a supervisory control method,which solves the problem of uncertain time delay by setting a supervisory controller on the robot.The validity of this method is verified by experimental results.

    Volume Rendering of 3 D M edical Image Based on M odularization
    Li Bin Tian Lian-fang Chen Ping He Yuan-lie Ye Guang-chun Mao Zong-yuan
    2006, 34(1):  77-81. 
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    In order to improve the visual effect and reconstruction eficiency of 3 D medical images.a method of vo-lume rendering is proposed based on modularization.In this method,the segmentation module is effectively corn-bined with the volume rendering,and a segmentation method based on the growing and cluster analyses in hybrid link region is developed to eliminate the disturbance of obstacles during the rotational display of 3 D image.Moreover,the modification of reconstructed kernel is performed based on the Raycasting algorithm,by adopting a resam-pling method with round--box selection and dynamic step-length adjustment to improve the reconstruction eficiency and by rotating light source and view angle to resample and reconstruct the interested region.Experiment,al results finally reveal the high eficiency and good display perform ance of the proposed method.

    Computer Science & Technology
    High-Efficiency Dynamic Task-Scheduling Algorithm for Grids
    Li Hui-xian Cheng Chun-tian Pang Liao-jun
    2006, 34(1):  82-85,104. 
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    The effective task scheduling in a grid environment is very difficult due t0 the dynamic requirements.va-nous loads and heterogeneous distributed resources,etc.of the system.So it is necessary to research a dynamic and adaptive algorithm of task scheduling.In this paper ,the swarm intelligence is introduced int0 the task schedu-Img m a grid environment,and a novel dynamic task-scheduling algorithm for a group of independent tasks is pro-posed,where the model describing the interaction between the wasp colony and the environment is used t0 imple ment the dynamic task scheduling in grids,and the contest problem is solved according t0 the seIf- organized domi-nance hierarchy of a wasp colony. Experimental results show that,compared with the existing methods,the proposed algorithm IS more adaptive to the dynamic grid environment,and possesses better scheduling pedformance.

    Computing Method of Correlation of Stock Data Streams
    Peng Hong Liu Yong Deng Wei-wei Zheng Qi-lun
    2006, 34(1):  86-89. 
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    Correlation analysis plays an important role in stock investment,detection and prediction.In order to quantitatively compute the corelation among different stocks,a method of computing the corelation among stock streams is proposed based orl the efficient one-pass scanning algorithm.By using the proposed method the corela-tion between two stocks can be computed in limited memory.Moreover.the proposed method is of lower cost in
    both time complexity and space complexity than the traditional method,and is efficient in the synchronous quoting of stock price,which is verified by experiments.

    Architecture of Knowledge Management-Modeling
    Liao Kai-ji Xi Jian-qing Liu Fa-gui Ma Liang-yu
    2006, 34(1):  90-95. 
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    In order to exchange knowledge accumulated by people at different levels and in different professional backgrounds,the multiple-view modeling method is adopted to build the knowledge management meta-models with diferent views,such as the strategy meta-model,the organization meta-model and the organizational knowledge flow management meta-model.Each meta-model is then redesigned in the object modeling language and an object concept system for the knowledge management modeling is built.A knowledge management-modeling tool is finally developed based on the proposed modeling system.As the proposed modeling system is object-oriented and modularized,the modeling architecture is reusable and integrated.

    Layered Model and Task Planning for Multi-Agent Cooperation
    Zhao Long-wen
    2006, 34(1):  96-100. 
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    In a multi-agent environment,multiple agents should be united to realize some complex tasks that are dificult to solve depending only on one agent because of being lacking in the capability or precondition of the sys-tem.Aiming at the cooperation of multiple agents,this paper proposes a layered model,in which the partners join hands to form a layered cooperation sequence via the joint capability.A large joint capability is then taken as the
    plan unit and the layered cooperation target is taken as the plan target.Thus,the task plan and management be-come simple and clear.Moreover,the methods of determ ining the partners and form ing the dynamic teams are also presented,with the task planning being finally discussed.

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