Journal of South China University of Technology(Natural Science Edition)

Performance of the Space-time Code Under the Correlated Fast Rayleigh Fading Channel

Chen Qi-ming Yin Jun-xun

2004, 32(8): 1-4.

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By using the theories of multivariate statistics and the matrix transformationthe difficulty in the perfor-mance analysis of the space-time code under complex channel modelwhich was applied to the MIMO systemwas evercome．The upper bound of the average pairwise error probability of the space-time code was also derived．It is concluded that the more the fading channels correlatethe worse the performance of the system is．The simulation results indicate the correctness of the conclusion．

A New Gabor Feature Extraction Method for Face Recognition

Wan Feng Du Ming-hui

2004, 32(8): 5-8,17.

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To utilize the Gabor feature for efficient face recognitiona new Gabor feature extraction method was pro-posed．Firstlya criterion with discriminating power was used to evaluate the classification ability of the Gabor coeffi -cientsand the Gabor coefficients most favorable to the recognition were selected to construct new Gabor features．Thenthe classification abilities of different local positions in the face were evaluatedand feature points were chosenat the positions with the strongest discriminating power．Finallythe adaptability of the new Gabor feature to illumina-tion and expression was tested．Experiment results show thatwith small samplesthe new feature extraction method can effectively increase the recognition ratereduce the number of featuresand is of certain adaptability to the envi -ronments．

Implementation and Design of the Conformance Test Scheme of the ITS Dedicated Short-ranged Communication Protocol

Tu Yu Xu Jian-min Zhong Hui-ling

2004, 32(8): 9-12.

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Athree-level structure of the ITS dedicated short -ranged communication protocol was proposed according to the open system interconnection reference model of the computer communication．Based on the methods and frame-work of the conformance test defined in the ISO standardthe testing method of the protocol conformance and the for-mal specification methods of the testing suits were then confirmedand the structure of the conformance testing system was designed．By applying the designed conformance testing system to the DSRC protocolthe conformance of the im-plementation and the text description of the protocol can be guaranteedthus establishing foundations for the intercon-nection and interoperation among DSRC facilities．

Influence of Oxygen Annealing on the Charge Storage Character of Ba_1-xSr_xTiO₃ Thin Film

Chen Ping, Huang Mei-qian, Li Bin, et al

2004, 32(8): 13-17.

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Ba 1－x Sr x TiO 3 （BST） thin films were firstly deposited on dry-oxidized silicon substrate by using the argon-ion beam sputtering technique and the silicon planner process．Nextan annealing was carried out in oxygen atmo-sphere under different conditions．By means of the aluminum etching technique and the photoetching techniquean a-luminum electrode was then madethus constructing the double dielectric capacitor structure of meta- l insulation-oxide-silicon （MIOS）．The charge storage character of the thin-film capacitor was finally investigated by the charge and dis-charge experiment．The results show thatwith the annealing temperature of no more than800℃the charge storageability of the thin film depends mainly on the oxygen ingredient．The more oxygen vacancies arethe greater the charge storage ability is．

Threshold Voltage Degradation Features of Double Polysilicon FLOTOX E²PROM

Luo Hong-wei, En Yun-fei, Yang Yin-tang, et al

2004, 32(8): 18-21.

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Based on the structure of FLOTOX E2PROM cellthe main factors influencing the reliability of FLOTOX E2PROM were analyzedincluding the degradation of the programmable windowsthe degradation of the charge retention characteristics and the time-dependent dielectric breakdown （TDDB）．It is found that the reliability of FLOTOX is much correlative with the quality of the tunnel oxide．A series of experiments show that the write／erase periodthe pulse voltage amplitude and the pulse width all affect the variation of the threshold voltage．It is also found that the trap charge resulting from the tunnel oxide proves to be the main cause of the threshold voltage degradation of FLOTOX E2PROMas it can increase or decrease the threshold voltage by affecting the injected electric field．

Influence of the Negative Third -order Dispersion on the Soliton Compression Effect in FSDD

Li Chao Wu Ting-wan

2004, 32(8): 22-24,29.

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By utilizing the theory of equivalent -effectthe nonlinear Schrodinger equation of FSDD （Fiber with Slow-
ly-decreasing Dispersion） with the negative third-order dispersion was discussed．It is found that the negative third-or-
der dispersion has a certain relation with the slowly-decreasing dispersion termthus proving that the negative third-or-
der dispersion helps to the compression effect of FSDD on solitonand there exists an optimal value of negative third-
order dispersion．The dynamic compression process was also analyzed．The results obtained by theoretical analysis ac-
cord well with those obtained by numerical simulation．

Leakage Control System Based on the Expert Controller for Air Preheaters

Yang Yu Ni Yun-feng Wang Hong Liu Ding

2004, 32(8): 25-29.

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The principle of the leakage control system for rotary air preheaters applied in a power plant was describedwith emphasis on the main causes of the leakage．A new approach based on the expert system mode was then present-edwhich implements the leakage control of the preheater by the rule method combining the compu-ter database with the knowledge base．The practical results show that the proposed control system can effectively reduce the air leakage to 90％ of that without leakage control systemthus guaranteeing the safe and normal running of the units．

Modeling and Simulation of the Main Circuit in High-power Arc-welding Inverters

Zhou Yi-qing Huang Shi-sheng Zhang Hong-bing

2004, 32(8): 30-33,46.

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In order to design high-power arc-welding inverters rationallya smal- l signal model of the main circuit in the high-power arc-welding inverter was establishedbased on the analysis of the main circuit in the high-power arc-welding inverter with phase-shifted full bridge zero-voltage-switched PWM （FB ZVS-PWM）．An approximate as-sumption was proposed during the model analysis in view of the effect of the leakage inductance in power transformerwhich causes a significant effect on the model precision．The magnitude and phase characteristics of the contro- l to-out -put transfer function of the model which varied with different model factorswere also analyzed．The results showthatalthough rational design of the output filter inductor plays an important role in reducing the sputter in CO 2 weld-ingthe model itself can not solve the problem of spatter completely．Implementing the intellective inverter is the key to success．

Design of a High-speed Data Sampling System Based on ISA Bus

Liu Su-yi Wang Guo-rong Guo Lie-en

2004, 32(8): 34-37.

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The hardware and software design of a high-speed data sampling system based on ISA bus was introduced．
In this systemfour pieces of ADS7810AD converters are started in turn at a certain interval to shorten the AD con-
verting time comparativelythus obtaining a high data sampling speed of2．6☞MHz in the system on ISA bus．Virtual
Device Driver （VxD）which is easy to transplant to other applied situationsis adopted to read the sampled data．The
sampled data are displayed and processed through a Windows application．Experiment results show that the perfor-
mances of the system can meet the requirements of the food sterilization device with high-voltage pulsed electric field．

Vibration Identification of the Gear Conditions for Gearbox Based on EMD Correlation Dimension

Chen Zhong Zhang Xian-min

2004, 32(8): 38-41.

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The theory of EMD （Empirical Mode Decomposition）as well as the correlation dimension （CD） and its characteristicswas firstly discussed in this paper．Thenaccording to the non-stationary feature and simple symptom monitoring of the vibration signals of a practical gearboxthe methods of EMD and CD were pre-sented．These two methods are respectively applied to the analysis of nonlinear and non-stationary signals as well as the measurement of the nonlinearity and non-regularity of the observed time series for a system．An EMD＆CD method was finally presented for identifying the vibration signals of a gearbox．The results indicate thatin various gear conditionsthe correlation dimensions of the intrinsic mode function related to the gear fault mode are obviously different with each other．This means that the EMD＆CD method can be used to extract the fault characteristics of a gear．

Experimental Research and CFD Analysis of the Cooling Water Flow in Engine Cylinder Head

Qu Sheng-guan, Xia Wei, Huang Rong-hua, et al

2004, 32(8): 42-46.

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Aiming at the cooling of the compact engine cylinder headthe flow distribution test of the cooling water which flows in the chamber of the transparent cylinder head was performed by using the flux and pressure measurement and the coloring agent method．The2D flow field of the cooling water in the complicated chamber was then obtained and some improvement was made on the improper structure of the chamber．Furthermorethe3D flow fields of the cooling water in the chambers of the actual cylinder heads before and after the improvement were obtained by means of the computational fluid dynamic （CFD） software FIRE．A comparative analysis was finally carried out between the test results and the CFD results．It is indicated thatafter the improvementthe flux and pressure distribution in the water chamber is properand the eddy and dead zone decrease．Meanwhilethe flow direction and the flux of the cooling water obtained by the numerical simulation accord well with the experiment and observation results．

The Study CH₄, CO₂ and O₂ to Syngas ( Ⅴ) : Thermal Wave Distribution in the Catalyst Bed

Dong Xin-fa Ji Tao Lin Wei-ming

2004, 32(8): 47-49,53.

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The thermal wave distribution in the N- i Ce-Cu-Li／Al 2 O 3 catalyst bed for the reaction of CH 4 CO 2 and O 2 to syngas was studied by a micro fixed-bed reactor．The effects of the bed temperature and the feed stocks on the thermal wave distribution were also investigated．The results indicate that there are obvious thermal waves in the oxyreforming reaction of CH 4 CO 2 and O 2 ．At the same furnace temperaturethe thermal wave intensity of the partial oxidation of methane is larger than that of the oxyreforming reaction of CH 4 CO 2 and O 2 ．No thermal wave was observed in the reforming reaction of CH 4 and CO 2 ．The phenomenon of thermal wave provides further evidences to the reaction mechanism of the oxyreforming reaction of CH 4 CO 2 and O 2 namelythe combustion-reformation mechanism．

Effect of Fluorine-containing Film Formation Conditions on Film Properties

Qin Zong-gen, Tu Wei-ping, Xia Zheng-bin, et al

2004, 32(8): 50-53.

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Fluorinated latex was prepared by means of seed emulsion polymerization．The contact angles between the fluorine-containing film and the water or hexadecane were measured by using the Kruss K12dynamic surface energy analyzer．The influences of the formation conditions of the fluorine-containing filmsuch as the formation temperature and the time of film formationthe film thicknessthe substrate and the dipping time on film properties were then studied．The results indicate that the formation conditions affect film properties greatly．A film with excellent properties can be prepared on glass surface by controlling the formation temperature at30☞℃the formation time for6．5h and the film thickness at100☞μm．

Co-polymerization of Methyl methacrylate and Aqueous Polyurethane

Qu Jin-qing Li Pei-yan Chen Huan-qin

2004, 32(8): 54-57,71.

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The polyurethane-acrylate (PUA)hybrid emulsion was prepared by the emulsion co-polymerization of water-borne polyurethane dispersion with methyl methacrylate (MMA).The effect of MMA content on the preparation of PUA emulsion and the properties of PUA coating film were then investigated.The structure and relative molecular mass of PUA were finally characterized by FTIR and GPC.It is found that , with the increasing of MMA content , for PUA emulsion, the average particle size and relative molecular mass increase , while the viscosity decreases;and for PUA coating film, the mechanism properties, water resistance and alcohol resis-tance improve, while the film gloss decreases .The optimal MMA content is 20%～ 30%of the total solid content (in mass)of PUA emulsion system.

Particle Size Distribution, Mineral Composition Distribution and Performance of Cement Prepared by Different Grinding Technology

Wu Xiao-mei Fan Yue-ming Guo Wen-ying

2004, 32(8): 58-63.

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The influences of the particle size distribution （PSD） and the mineral composition distribution of cement prepared by different grinding technology on the physical performances of cement and concrete were investigated．The results show that there is a close relationship between PSD and grinding conditions as well as grinding system parameters．Narrower PSD can be obtained by using the high-efficiency separator with higher circulating-load and proper specific surface area．With narrower PSD and higher specific surface areamost of C 3 S in clinker can efficiently enrich in particles smaller than30☞μmdue to the good grindability and enrichment of C 3 S in cement particles．When the qualities of clinker and admixturesas well as the specific surface area of cement are kept stablenarrower PSD （most particles are in the size range of0～30☞μm） results in higher water demand for normal consistency of cement pastelonger setting timelower1-day compressive strength and higher3-and28-day compres-
sive strengths．The concrete prepared from this cement will be of great bleeding and low1-day compressive strength and high3-and28-day compressive strengths．

Microstructure of SiC /Al₂O₃ /Al Composite Formed by the Direct Oxidation of Aluminum Alloys

Zhou Xi-ya Gao Qin

2004, 32(8): 64-67.

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The microstructure of SiC/Al 2 O 3 /Al composite formed by the direct oxidation of aluminum alloys which infiltrated into the SiC precast part was analyzed by means of XRD, TEM and metallomicroscope .It is found that the composite is composed of α-Al 2 O 3 , SiC, Al 4 O 4 C, Al and Si .α-Al 2 O 3 is the skeleton phase of the composite, which is 3D-interconnected and is of clear interfaces.It is also found that Al and Si are wrapped in the grains of α-Al 2 O 3 , while at another main phase , SiC grains are separated from other phases .In addition , there is Al 4 O 4 C in the composite , which means that SiC grains have reacted with aluminum and oxygen in the growth of the composite .

Optimization Model of the Area Logistics System

Wu Jian Shi Zhong-ke

2004, 32(8): 68-71.

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Some problems in area logisticssuch as the materials transportationthe reasonable storehouse distributionthe output of products and the storehouse capacitywere optimally analyzed and investigated．An integrated optimization model of the area logistics system was then presentedwhich was solved by means of mix-integer programming．The proposed model was finally applied to the agricultural productionand the computational results verify the correctness．This model can be used to solve some problems in actual area logistics systems．

A Curved Plate Element with Rib-beam

Shu Zhong-ying, Du Wen-bing, Chen Qin-zhong, et al

2004, 32(8): 72-77.

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By treating the deck and the rib-beam as a wholeand by using the displacement modes of the Mindlin plate element and the8-node Serendipity element in the calculationa curved plate element with rib-beam was constructed in view of the nonlinearity of the structure．In the Mindlin plate elementthe displacement and the angular displacement are interpolated independently．In the proposed element modelthe effect of rib-beam is taken into accountand the slab and rib-beam are combined into one element．Thereforethe displacement incoordination of the joint in the nodes of the plate element and the rid-beam element no longer exists．Numerical examples show that the proposed method is of the advantages of reliable calculation results and less freedom degreeand it is applicable to the nonlinear spatial computation of the large-span curved girder bridge．

Automatic Trigger of the Traffic Plan in Tunnel Monitoring and Control System

Fu Xin-sha Yang Hua-jian

2004, 32(8): 78-81.

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A tunnel monitoring and control system was introduced by a corresponding development example．When emergency occurs in the tunnel （with an alert）the system can respond to all kinds of events without losing any important data and alert informationand can automatically trigger off a traffic control plan．This may alert the operator to the emergency in timeso that he can take measures to prevent traffic accidents from taking placeprovide immediate solutions to traffic accidentsand guarantee quick recovery of the traffic．The proposed system is stable and operates easily．The anticipated results can thus be attained．

Multiclass Classification Based on the One-class Classification and its Application

Li Huan-rong Lin Jian

2004, 32(8): 82-88. doi:1000-565X(2004)08-0082-07

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Relationship management is the key to the success of a modern firm．As a new method to process the nonlinear datathe Kernel method provides a feasible scheme to analyze the complex relationship networks in firms．In this paperbased on the analysis of the core concepts in the Kernel methodthe basic principles of the multiclass classification based on the one-class classification were studiedand the reliability function applied to the multiclass classification was put forwardwhich makes the classification results more reliable．Finallythe method was applied to the data analysis of the relationships between a firm and its suppliers．The results reveal the validity of the proposed classification method．

Properties of H₂S-producing Bacterium in the Sediment from the Near-shore Shrimp-cultural Pond

Wang Ya-nan Peng Zhi-ying

2004, 32(8): 89-92.

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By means of the cellular morphology and the physiologica- l biochemical featuresand combining with partial16S rDNA gene sequencing results of the bacteriumthe amountcommunity structure and their distributions of H 2 S-producing bacterium in the sediment of the near -shore shrimp-cultural pond were analyzed．The results indicate that the most of the bacteria population includes the genus of BacillusHalobacillus and Microbiumwhile other genus can produce few H 2 S．It is also indicated that sulfate-reducing bacteria is the smallest po-pulation in the sediment．

Investigation into the Microwave-assisted Extraction Technology for Astragalus Polysaccharide

Gong Sheng-zhao Yang Zhuo-ru

2004, 32(8): 93-96.

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The microwave-assisted extraction technology for astragalus polysaccharide was studiedwith water as the extraction solvent．The optimal extraction conditions were obtained as follows： the ratio of water to the material12∶1；pH value9regulated by saturated limewater；two doses of microwave radiation （300☞W） for10min．Precipitate was obtained after the extracted liquor was concentrated in vacuum and blended with ethanol．The crude product of as-tragalus polysaccharide with the yield of14．6％ and the purity of88．1％ was then obtained after the precipitate was washed with ethanol for several times and dried in vacuum．It is found thatcompared with the direct -heating extrac-tionthe microwave-assisted extraction can shorten the extraction durationreduce the consumption of the solvent and improve the yield of astragalus polysaccharide．

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