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    25 June 2005, Volume 33 Issue 6
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    Design and Simulation of a Chaotic Signal Generator for Secure Communication System
    Long Min Qiu Shui-sheng Peng Fei
    2005, 33(6):  1-4. 
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    A secure communication scheme based on the asymmetric structure of chaotic signal generators of the transmitter and the receiver is proposed. On the basis of the error-feedback synchronization theory, chaotic signal generators with different special auxiliary networks are respectively designed for both the transmitter and the recei-ver.Only by knowing the parameters of the original chaotic system ,the constitutions of the special auxiliary net-work and the transmitted signal,the receiver can reconstruct the chaotic system,design coresponding auxiliary network,abstract chaotic signals for the encryption and obtain the demodulation message.The simulated results show that the special auxiliary networks in the receiver and the transmitter enhance the security of the secure communica-tion system,thus resulting in excellent noise robustness of the system.

    Clock Tree Analysis in Design of Synchronous Digital Integrated Circuit
    Yin Rui-xiang Guo Rong Chen Min
    2005, 33(6):  5-8. 
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    In designing synchronous digital integrated circuits,the design of clock tree is an important component,which may greatly affect the performance and reliability of the system. In this paper. the constitution of the syn.chronous digital system and the definition of clock skew are introduced,and a designing method for clock tree is presented.Based on the proposed method,the automatic clock tree synthesis and the structure-specified clock tree
    synthesis of 8051 chip are then perform ed using Astro.The results indicate that,compared with the results obtained by the automatic clock tree synthesis,better results can be obtained by the proposed method. Moreover,the solu-tion to the gate clock is presented.

    Decoding of TCM Codes Based on IEEE 802.16a
    Yin Jun-xun Liu Ting-ting Yao Zhi-qiang Liu Yong-yu
    2005, 33(6):  9-13,35. 
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    W ith the aim of designing and implementing the eror control part in the wideband wireless access sys.tern ,three decoding methods for TCM codes are proposed based on the wireless metropolitan standard IEEE 802.1 6a.The dimculties in the implementation of the decoding algorithms are then theoretically analyzed and corn-pared.Moreover,computer simulation with fix-point computation is carried out,thus obtaining the curves of the bit eror rate performance of the decoding algorithms for different TCM codes.The theoretical and simulated results in-dicate that there is no best algorithm for the decoding of TCM codes. The specific decoding methods for different TCM codes in the standard are presented at the end of the paper.

    A Secure Payment Protocol Using Mobile Agents Based on Verifiable Secret Sharing
    Liu Yi Xu Wen-li Wang Yu-min
    2005, 33(6):  14-17. 
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    The security of mobile agent is an obstacle that has to be faced in mobile agent technology. In order to protect the information confidentiality in the payments using mobile agents,this paper presents a secure payment protocol based on mobile agents by adopting the verifiable secret sharing scheme of Pedersen.Moreover,the per-form ances of the proposed protocol,including the security,the non-repudiation and the running efi ciency,are ana-lyzed and discussed in detail.The results show that,compared with the existing methods,the proposed protocol is more practically valuable because it ensures the security of payment information with ease while possessing a suit-able running eficiency,and improves the security and flexibility of the payment system.

    Solution to and Analysis of the Model of Dedicated Short-Range Communication Protocol
    Zhong Hui-ling Xu Jian-min Peng Xuan-rong
    2005, 33(6):  18-22. 
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    In order to determine the important parameters of DSRC(Dedicated Short-Range Communication)proto-col,the communication process is divided into two phases,namely, the reservation phase and the data transmission phase.The mathematical model of the protocol is then established stage by stage based on the queuing theory .The time delay and the throughput in the reservation phase are then analyzed and discussed. Moreover,the calculation method and corresponding results of the main parameters and the performance targets in the data transmission Dhase are presented. This calculation is caried out on condition that the data transmission time foilows fixed-length distri. bution and negative index distribution. Solutions are also given to those cases where the application c0ndition d0es not meet the assumptions.

    ID-Based Chameleon Signature Scheme from Bilinear Pairing
    Du Xin-jun Wang Ying Ge Jian-hua Wang Yu-min
    2005, 33(6):  23-27. 
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    Chameleon signature schemes are non-interactive signature schemes based on a Hash-and-Sign para-d gm,and are s m lar in efficiency to original signature schemes. However,Chameleon signature schemes Dos-sess non-tranterability,that is to say, only the designated recipient can verify the validitv of a signature.In this papc,an ID-based Chameleon Hash function from the bilinear pairing is proposed, according to which an ID-based Chameleon signature scheme is constructed. As Compared with the conventional Chameleon Hash tunctions,the owner of a public Hash key in the ID-based Chameleon signature scheme does not need to re-trieve the assoc ated secret key.The proposed scheme possesses all the attributes of original Chameleon signa-tures.Moreover,it s of the advantages of the ID-based cryptography based on the bilinear pairing.

    Delay Simulation and Analysis in the Design of Complicated Programmable Logic Devices
    2005, 33(6):  28-31. 
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    In order to investigate the effect of the delay performance of complicated programmable logic devices on the delay in the digital system design,the mathematical model of the digital logic delay unit core was studied,the basic digital logic delay unit core was realized in hard description language and with graphics,and a multi-delay unit was put forward via the digital cote multiplex from the basic digital core.Moreover,with the help of the elec-tronic design automation software,digital delay components in different complicated programmable logic devices were simulated and analyzed.The results indicate that the delay in the digital logic design is related to three fac-tots,namely,the delay performance of the complicated programmable logic device,the selecting logic block in the placement and the routing,and the interlinking sources.Thus,theoretical and experimental foundations for the de-sign and analysis of the delay in complicated programmable logic systems were laid.

    Pattern Recognition of Trafic Flows in Elevator Group Control Systems Based on SVM
    Xu Yu-ge Luo Fei
    2005, 33(6):  32-35. 
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    Aiming at the pattern recognition of traffic flows in elevator group control systems,a method based on the multi-value classification SVM (Support Vector Machine)is put forward.Moreover,the design procedure of the pattern recognition is presented and the corresponding pattern classifier is established.The results demonstrate that,by using the proposed method,different traffic flow modes can be recognized accurately.Furthermore,it is proved by comparison experiments that the proposed method possesses powerful generalization ability and is of greater re-cognition veracity than the methods based on the neural networks.

    An Open Computerized Numerical Control Sysrem with Module Architecture
    Gao Jun-li Li Di Zheng Shi-xiong Feng Shou-ting
    2005, 33(6):  36-40. 
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    A CNC(Computerized Numerical Control)system with open architecture is presented based on an au thoritative standard-OMAC(Open Modular Architecture Controller)standard.This system consists of modules modeled by UML(Unified Modeling Language),which can be configured or reconfigured statically or dynamically to meet various machining requirements. Moreover,MDA (Model.Driven Architecture) is adopted to verify the
    svstem function at the model level before the realization of the system,instead of at the traditional program code level,thus greatly shortening the development cycle of prod ucts.It is concluded that the.NET component tech-nology is much more suitable for implementing CNC mod ules as compared with DLL,COM an d DCOM.

    Error Model and Parameter Identification for Serial-Parallel Cancer Curing M achines Using Ultrasonic
    Fang Qiang Fan Liang-zhi
    2005, 33(6):  41-45. 
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    The actual position accuracy of the 5-DOF (Degree of Freedom)serial-parallel manipulator 0f a HIFU(High-Intensity Focused Ultrasonic)curing machine is analyzed on the basis of the actual error models of the mo-ving platform,the stability platform and the extension pole.as well as by means of the redundant restriction param-eter identification.With a 3-RPS serial-parallel manipulator as the research object.the model parameters of the
    controllers of the curing machine are adjusted via the error parameter identification and position accuracv arialysis.and a higher position accuracy is achieved,thus meeting the positioning requirements for HIFU treatment more sat-isfactorily.The simulated results indicate that,during the practical measurement,about 50 test points are enough.with a maximum total eror of the focus less than 0.5 mm and a maximum measurement eror less than 0.2 mm,e-yen within 0.05 mm.The most remarkable merit of the proposed method is that no more extra configurati0n trans-ducers or sensors are needed during the parameter identification,which makes it possible for the manipulator to run on line in practical situations.

    Dynamic Simulation on Method for Wind Turbine Based Induction Motor
    Wu Jie Xu Yan-hao
    2005, 33(6):  46-49,78. 
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    In order to improve the controlling perform ance of wind.energy conversion systems,a dynamic wind turbine simulator with the same mechanical characteristics as those of the actual wind turbines is put fi)rward to design,evaluate and test actual wind turbine systems.When the load in a sampling period is constant.the simulator can evaluate the load at each sampling time according to the feedback speed of the induction motor. calculate the output  acceleration of a real turbine according to the characteristics of wind turbines, and obtain the nlagnetic t0rque in.struction of the induction motor by the comparison with the calculated acceleration value, whilfI the magnetic toraue of the induction motor can be regulated by the direct torque control(DTC)flnr the transducer.The simulated re-sults indicate that the evaluated loads accord well with the actual ones, and that the dynamic characteristics of the proposed simulator are similar to those of the actual wind turbines.

    Adsorption Performance of Lignosulfonates on Coal-Water Interface
    Zhang Yan-lin Qiu Xue-qing Wang Wei-xing Yang Dong-jie
    2005, 33(6):  50-54. 
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    In order to understand the influence of surfactants,namely,lignosulfonates,on the preparation propertv of coal‘water slurry,the adsorption performance of lignosulfonates on coal-water interface was investigated bv mea-suring the adsorption isotherms,thus revealing the influences of the relative molecular masses of lignosulfonates.the metal cations，the pH and the temperature of coal-water suspension,as well as the stirring time.The resuIts show that the adsorption capacity increases with the increase in the relative molecular mass of lignosulfonate. and that univalent cation is helpful to the improvement of adsorption capacity because it can be more easilv adsorbed onto coal‘water interface.Moreover,it is indicated that the pH and the temperature of the SUSpension ,as well as the stiring time are important parameters to be controlled in the suspension preparation because they will greatlv influ-ence the adsorption of lignosulfonates on coal·water interface． Furtherm ore，the corresponding adsorption type was researched by the adsorption experiments of lignosulfonates with different relative molecular masses． It is then con-cluded that the first adsorption level follows the adsorption model of Langmuir.The reason for the weak adsorption intensity in experiments was also preliminarily discussed.

    Inhibiting Mechanism of Sodium Dithiocarbamate to the Corrosion of Mild Steel in Sulfuric Acid
    2005, 33(6):  55-58. 
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    In order to investigate the inhibiting mechanism of sodium dithiocarbamate(DTC)to the corrosion of mild steelin sulfuric acid.a series of dithiocarbamate corosion inhibitors were synthesized by using amine and CS,as the reactants and were then characterized bv IR spectra.Moreover,the inhibition effect of DTC to mild steel in sulfuric acid was investigated by means of the weight lOSS and the electrochemical methods.The resuhs indicate that DTC can obviously inhibit the corosion of mild steelin 0.5 no1/L H2SO4 dsolution.with the inhibition eficiency in.creasing with the concentration of DTC.It is also indicated that DTC behaves as a mixed.type corrosion inhibitor whose inhibition eficiency is significantly influenced by the various substituting groups on nitrogen atoms.

    Supercritical CO2 Complexing Extraction of Heavy Metals from Pogostemon Cabfin Benth
    Dang Zhi Zhu Zhi-xin Wen Zhen Li Qiong
    2005, 33(6):  59-62. 
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    Sodium diethyldithiocarbamate(NaDDTC)was used as the complexing agent for the removal of heavymetals in Pogostemon cablin Benth,a Chinese herbal medicine,by supercritical carbon dioxide complexing extrac-tion.The extraction conditions including the pressure,the temperature and the amount of NaDDTC were then opti-mized by orthogonal experiments.The experimental results show that,in the best extraction conditions,that is,70℃of extraction temperature,25 MPa of extraction pressure and 15.79% (mass fraction)of the complexing a-gent,the extraction rates of Cu,Pb and Zn are respectively up to 55.2% ,59.2% and 53.3%.The proposed method can thus be used as a new approach to the removal of the heavy metals in Chinese herbal medicines.

    Analysis of the Removal of Heavy Metals in Landfill Leachate by Biological Treatment
    Yang Zhi-quan Zhou Shao-qi
    2005, 33(6):  63-67. 
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    In order to efi ciently treat landfill leachate，a sort of efluent containing complex pollutants,ICP -MS analysis was used to measure the heavy metals contained in the landfill leachate generated from Datianshan landrill in Guangzhou．46 kinds of heavy metals in the landfill leachate were detected,1 0 of which belong to the environ.mental priority pollutants considered by Environmental Protection Agency in USA. In these 1 0 priority pollutants,the mass concentrations of Cr,Ni,Zn,Cu and Pb are comparatively high,especially those of Cr and Zn.which are more than 1 00 μg/L. Moreover,a set of simultaneous aerobic.anaerobic bioreactor was used t()treat the landrill  leachate.The results demonstrate that 10 of the 46 pollutants have a removal rate of more than 70%, 12 of 50% ~69%,and the removal rates of Cr and Zn all exceed 60%.In addition, in the ten priority pollutants.the removal
    rates of Cr,Zn,As,Pb and Se account for more than 60% .

    Structures and Appearances of Several Diferent Starch Granules
    Zhang Ben-shan Liu Pei-ling
    2005, 33(6):  68-73. 
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    Light Microscopy and Scanning Electron Microscopy were used to observe the structures and overall ap-pearances of several kinds of starch granules of potato,tapioca and corn.The hilums,growth rings and structural features of these three kinds of starch granules were systematically analyzed. Moreover,POCl3was used as the cross-linking reagent to modify the granules,thus obtaining more clear observation results. The results indicate that the starch granules of potato,tapioca and con3 are all of hilums and growth rings. The shapes and the schematic structures of the granules are presented in this paper ,and the conceptions of the head and the tail for potato and tapioca starch granules are also described.

    Consolidation in-situ Forming of Aluminium Oxide Ceramic by Acetate Starch
    Chen Ling Song Xian-liang Ye Jian-dong Li Xiao-xi
    2005, 33(6):  74-78. 
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    A new consolidation in-situ forming process for high-perform ance aluminium oxide ceramic using starch as the consolidator/binder was investigated.The effects of different contents of acetate starch on the rheologicl be-haviour of the ceramic slip,as well as the linear shrinkage,density,strength and microstructure of the green body were discussed.The results indicate that,when the content of acetate starch is 0.5% ~1.5% (mass fraction).the apparent viscosity of alumina slurry,which is always less than 1 Pa·s,increases with the content.Moreover,with the increase in starch content,the linear shrinkage rate and the density of the dried body decrease. while the strength of the dried body almost linearly increases.Green body with homogeneously-distributed density and pore size was also obtained in this research. It is concluded that Al2O3ceramics can be consolidation in-situ formed.based on the gelling network of therm ally swelled and gelatinized acetate starch.

    Efects of Volatile Com pounds in Tobacco on Sm oke Aroma
    Wu Shao-xiong Guo Si-yuan Li Lin Cai Miao-yan Wang Bao-xing Li Zhong Jiang
    2005, 33(6):  79-84,88. 
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    In order to investigate the relationship between tobacco volatiles and the smoke quality. the volatile compounds in about 3 000 tobacco samples from China and abroad were systematically analyzed by capillary gas chromatography(GC)and gas chromatography-mass spectrometry (GC-MS).thus revealing the influences of the growing area,the variety,the planting condition,t}le climate,the stalk position and the a ng on the volatile compo unds and the smoke quality.The results show that the volatile compo unds in diferent tobaccos are the same in variety but are greatly diferent in content.The evaluation results of the smo ke strength. irritation.flavor and off-fla-Vor of the roasted tobaccos grown in diferent al~ts indicate that all these items are remarkably diferent in qualitv.which means that the smo ke qu ality of toba ccos can be roughly evaluated by the rather ab undant volatile compound

    Separation and Identification of Flavonoids in Extracts of Prunus Mume by Microemulsion Chromatography
    Han Ming Zeng Qing-xiao Xiao Geng-sheng Chen Wei-dong Xu Yu-juan Zhang You-sheng
    2005, 33(6):  85-88. 
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    This paper proposes a new method for the separation and identification of flavonoids in Prunus mume by microemulsion chromatography.By using 10%formic acid for the pH adjustment,as well as with SDS/n-C4H9OH/n-C7H16/H2O microemulsion and rutin respectively as the eluant and the control sample on the polyamide film ,the flavonoids were entirely separated by the proposed method.Th e separated results indicate that five flavonoid spots can be obtained from the ethyl acetate extract,four from chloroform ,one from petroleum ether and one from n-hexanel,It is also indicated that,compared with the general chromatography methods with C4H9OH/CH3COOH/H2O as the elu-ant,the propo sed microemulsion chromatography is of greater sensitivity of detection and better separation effect.

    Dynamic Calculating Models of High-Rise Building Structures with Basements
    Cheng Zhi-hui Zhang Jun-sheng
    2005, 33(6):  89-93. 
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    To obtain the conditions for taking the t0p-floor of the basement as the fix．end of the superstructure.the dynamic calculating models of high-rise building structures with basements are discussed. The dynamic characteris-tics of shear buildings,bending buildings,shear-bending buildings and bending-shear buildings with basements are then respectively calculated and analyzed.Moreover,the effects of the mass and rigiditv of the basement on the free vibration period are investigated.The results demonstrate that,for all high-rise bending buildings,most high.rise shear-bending/bending-shear buildings and the high-rise shear buildings with a little ratio of basement shear rigiditv to standard shear rigidity,that is,less than 2,the effect of the basement cannot be neglected in the dynamic calcu-lation,and that the top slab of the basement cannot be taken as the fix.end of the superstructure

    Cavity Field Spectra of Two Diferent Atoms Interacting with Two-Mode Field in Thermal States
    Zhang Gui-ruing Li Yue-ke Gao Yun-feng
    2005, 33(6):  94-97. 
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    In order to obtain the cavity field spectra of two different atoms interacting with a two.mode field.the ex-pression of the cavity field spectra in an initial thermal field with random intensity is derived by solving the eigen equation,and some numerical results are presented.Moreover,the effects of the relative coupling constant and the initial field intensity on the spectrum structure al"e discussed.It is found that(1)a two-peak structure appears for
    each mode spectrum when the relative coupling constant is naught and the initial field is relatively weak;(2)the two peaks gradually draw close to each other with the increase in relative coupling constant;(3)each mode spec-trum appears as a single peak when the relative coupling constant achieves 1;and(4)when the average photon number of one mode increases,the distance between the pair peaks of this mode decreases,while that of the other
    mode increases.

    Oscillation Criteria for the Second-Order Quasi-Linear Diferential Equations with Damping
    Jin Chu-hua Xu Zhi-ting Luo Jiao-wan
    2005, 33(6):  98-102. 
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    W ith the help of Young inequality and HiSld inequality,the oscillatory property of a class of quasi-linear differential equations is investigated by using the Riccati-type transformation and the method of H function.The in-tegral conditions for the oscillation of all the solutions of the equations are also given.Thus,the corresponding re-suits in recent literatures are generalized and improved.By choosing appropriate functions H and Φ ,one can derive
    a number of explicit oscillation criteria.Even for the equation without damping,the coresponding results are still different from the form er ones．An example is finally presented to show the validity of the main theorems.

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