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

Robust Stabilization of Uncertain Large-scale System with Infinite Delay

Peng Shi-guo Deng Fei-qi He Rui-wen

2004, 32(1): 1-4.

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The robust stability of an uncertain large-scale integro-differential system with infinite delay was discussed．Sufficient conditions of robust global uniformly asymptotical stability of the system were obtained by utilizing Lozinskii’s matrix measure and differential inequality．These conditions are very pithy and verifiableand many kinds of matrix norms can be chosen when necessary with the needs in the application of the conditions．This research indicates that state feedback controller without delay can be chosen to guarantee the robust global uniformly asymptotical stability of integro-differential systems．A simulated example was proposed to illustrate the validity of the results．

Strategy Interpreting Arithmetic of Ethernet-based Virtual Instrument Measurement and Control System

Liu Gui-xiong Yi Jing-rong Fang Xiao-dong

2004, 32(1): 5-8.

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To follow the present -day trend to integrate the virtual instrument with Ethernet -based measurement -control systema virtual instrument measurement and control platform based on Ethernet was proposedwhere the reversed Polish expression and its interpreting arithmetic were used to interpret and transfer the Ethernet -based virtual instrument measuring and controlling strategy described by graphical components during the rerun-ning process．The simulation results show that the application of reversed Polish expression significantly simplify the program from interpreting and transferring strategy scheme to micro commandsthus saving system resource and speeding up the interpreting and transferring process．

Digital Image Analysis of Foamed Aluminium's Microstructure and Its Distribution

Zhang Hong, Huang Xiao-qing, Tang Li -qun, et al

2004, 32(1): 9-13.

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Digital images of foamed aluminium’s microstructure were processed using digital image processing technology and software in order to obtain the statistical distribution feature of the main microstructure parame-ters of foamed aluminiumthus predicting the macro-behaviors of foamed aluminium from its microstructure so as to provide a helpful reference for the improvement of the fabrication technique and the optimized design of foamed aluminium structure．The statistical distributions of the parameters of foamed aluminiumsuch as aper-ture and porositywere obtained．The study shows that digital image analysis helps to predict the macro-behav-ior of foamed aluminium from its microstructureand is essential for the numerical simulation of foamed alumini -
um．At lastthree-dimension digital image analysis of the foamed aluminium’s microstructure was prospected．

A Cryogenic Treatment System Controlled by Computers

Zhang Yang Zeng zhi-xin Shi Chang-jun

2004, 32(1): 14-18.

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Simulation and Modeling of Direct Torque Control of Permanent-magnet Synchronous Motor Based on MATLAB/ Simulink

Xie Yun-xiang Lu Zhu-qiang

2004, 32(1): 19-23.

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The modeling of direct torque control system of permanent-magnet synchronous motor based on MATLAB/Simulink was introduced, and the simulation of the system was carried out to research on the effect of PI controller parameters on the system performances.Also , the relationship between torque hysteresis loop' s width and torque ripple amplitude was analyzed.The results show that the direct torque control system gives a good response to the rotation speed and torque , and that the torque ripple amplitude decreases with the reduction of torque hysteresis loop' swidth.The PI controller parameters K p and K i should be properly matched to achieve
excellent system performance , for a large scaling factor K p will accelerate the system' s dynamic response, while the integral coefficient K i mainly influences the system' s static error.

A RST-based Improved NN Model for Fault Diagnosis of High Voltage Transmission Line System

Liao Zhi-wei Wang Gang Ye Qing- hua

2004, 32(1): 24-28.

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To overcome the mis-diagnosis of fault caused by the distortion of rea- l time diagnosis information during the generation and transfer processeson the basis of the research into the RST （Rough Set Theory）-based fault diagnosis model of high voltage transmission line system and by utilizing the generalization ability of neural network （NN） and the great qualitative analysis ability of RSTthe fault diagnosis model with the combination of RST and NN was constructed．In this approachRST was used to extract knowledge region data set from diagnosis samplesand the basic structure of NN was built on the basis of diagnosis knowledge attribute．Thus the intelligence and fault tolerance performance of diagnosis NN system were improved．The validity and commonality of the proposed model were proved by the comparison of simulation results of the fault diagnosis system．The proposed model has excellent fault tolerance performance even though the diagnosis information is not completeso it is of important practical value in the rea- l time fault diagnosis of electric power system．

Turn-off Model of the New Type Power Device MCT

Cai L- i juan　Zou Zu-bing

2004, 32(1): 29-32.

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The fundamental structures and working principles of the new-type power device MCT （MOS-con-trolled Thyristor） were introducedand the physical state model in turn-off status modeled mathematically by the state-average method was discussed．The whole device was regarded as a systemwhose stability was analyzed by the state-space analytical method．Thereby the maximum controllable turn-off current of MCTand the relationship between the current and MCT’s structural parameters were deduced．The validity of conclusions drawn here was proved using MATLAB／Simulink．

Electric Field Calculation and Structural Parameter Determination of Resistance Divider

Niu Hai-qing

2004, 32(1): 33-36.

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The electric fields of several resistance dividers－the substitute devices of electromagnetic voltage inductor （PT）－were analyzed and calculated to determine the structural parameters of the divider．In the cal -culation of the electric fieldthe Finite Element Method of simple syntonization field （sin field） was usedand the voltage distribution of each point in the field in the form of complex number was obtained．By comparing the amplitude errorsphase-angle errors and the maximum electric field strength of the pointsthe best scheme for resistance divider design was optimized and the corresponding amplitude error -frequency characteristic was ana-
lyzed．Finally the correctness of divider design and field calculation was validated using electric circuit．

Simultaneous Desulfurization and Denitrification from Flue Gas by Using Urea/ Additive Solution( Ⅰ) :Kinetic Equation of Urea Consumption in Absorption Reaction

Cen Chao-ping Gu Guo-bang

2004, 32(1): 37-40.

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The kinetic equation of urea consumption in absorption reaction was studied in the process of simulta-neous desulfurization and denitrification from flue gas by using urea／additive solution．The experimental results how that the relationship between urea concentration and time is linearand the reaction order is zero．The rate constant k of absorption reaction of urea solution without additive is0．8571mmol·L －1 min －1 while k is res-pectively1． 945mmo1·L －1 ·min －1 and1．1521mmo1·L －1 ·min －1 with the additives of ethylenediamine and ammonium phosphate．The rate constant of absorption reaction in the simultaneous desulfurization and denitrification is greater than the sum of those obtained in separate desulfurization and denitrificationwhich shows the synergism in the process of simultaneous desulfurization and denitrification．

Natural Convection Boiling Heat Transfer in Enhanced Heat Transfer Tubes

Zhang Ya-jun, Ouyang Rong, Deng Xian-he, et al

2004, 32(1): 41-43,48.

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Preparation and Adsorption Characteristics of Adsorptive Ceramic -fiber Functional Paper

Fan Juan, Fang Yu-tang, Ding Jing, et al

2004, 32(1): 44-48.

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A new sort of functional paper with excellent adsorptive performance was prepared with ceramicfiber paper as matrixby sequentially dipping in the solutions of water glass （Na₂SiO₃）precipitant and hydrochloric acid．This kind of functional paper can be applied to prepare the core of adsorption type rotary dehumidifier．The effects of dipping conditions on the adsorptive performance were discussed．The surface morphology and the pore size were disclosed with SEM and Porous Medium Surface Area Analyzerthus discovering the adsorptive characteristics．Experimental results show that silica gel is deposited on the surface and in the apertures of the matrix uniformlywith the average pore size of 0.4939～3.907 nm．The prepared functional paper has quite high adsorption rate in the first 20minutes and will get its adsorption saturation within5hours．The saturated adsorptive capacity can reach 52.19g／m²in the conditions of 26．67％（mass fraction） Na₂SiO₃ 15％（mass fraction） precipitant and0.5mol ／L HCl．

Influence of Additives on Various VPO Catalysts Prepared by Coprecipitation Process

Ye Dai-qi, Fu Ming-li, Liang Hong, et al

2004, 32(1): 49-55,64.

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The effect of additives on the structures and properties of various VPO catalysts used for the select tive oxidation of n-butane to maleic anhydride was investigated．A series of VPO catalysts were prepared by coprecipitation process with the addition of ZrCoCeZnSnKBa and Bi as promoters．The catalytic performance test was conducted in a fixed-bed micro-reactor at atmospheric pressure．The results show that the catalytic behavior is affected remarkably by additives．For n-butane oxidation activitythe effect of various elements follows the order of VPO-Zr＞VPO-Co＞VPO-Zn＞VPO-Sn＞VPO-Bi＞VPO-Ce＞VPO-Ba＞VPO-K＞VPO．For MA （Maleic Anhydride） selectivitythe promoting effect is in the order of VPO-Zr＞VPO-Ce＞VPO-Zn＞VPO-Sn＞VPO-Co＞VPO-Bi＞VPO＞VPO-Ba＞VPO-K．Test results of catalysts including XRDFTIR and TGA／DTG indicate that no remarkable change occurs in the bulk structure due to the addition of elementsboth for precursor and final catalysts．All precursor catalysts are composed of VOPO_4.0.5H₂Owhile in the final samples（VO）₂P₂O₇is formed accompanied by less amounts of α-VOPO_4.XPS measurement suggests the enrichment of PV and O on the surface of catalystsand the amount of surface oxygen species is directly related to the catalyst activity．

Synthesis of Cu-HMS Molecular Sieve and Aromatic Hydrocarbon Oxidation Using Cu-HMS

Zhang Mei-ying, Wang Le-fu, Ji Shan, et al

2004, 32(1): 56-60.

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A copper -containing molecular sieve Cu-HMS was synthesized using the neutral templating pathway at room temperature．Then the product was used as heterogeneous catalyst for the oxidation of cumene under mild conditions．The results show that Cu-HMS-3with copper nitrate as copper source has excellent catalytic activityhigh cumene conversion and cumene hydroperoxide selectivitythat is39．6％ and98．5％．The catalyst can be recycled．Furthermorethe oxidations of toluene and ethylbenzene were investigated with Cu-HMS-3as catalyst．It is found that there is no oxidation reaction observed for toluene．The activities of the three aromatic hydrocarbons follow the order of toluene≪ethylbenzene＜cumene．

All-optical Switching Effect of Poly( Vinyl Carbazole) with Azobenzene Chromophores

Yao Sheng-lan, Wu Shui-zhu, She Wei-long, et al

2004, 32(1): 61-64.

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The al- l optical switching polymer composites with poly（vinyl carbazole） as the main material and azobenzene dyes including DR-1DR-13and DY-7as the object materials were successfully prepared by the adulteration method．An excellent al- l optical switching effect driven by the pump beam with low power （12．5～30mW514nm） had been observed during the light -responding measure．At the same timethe influencing factors of the al- l optical switching effectsuch as the modulation frequency of pump beamthe content and the structure of chromophoreswere comparatively studied．It is shown thatin the same experimental conditionthe al- l optical switching effect will be enhanced with the increasing of chromophore molecular polarity．Higher chromophore content （20％） makes the al- l optical switching effect strongerand the effect under lower modula-tion frequency （30Hz） is stronger than that under higher modulation frequency （50Hz）．

Syntheses of Poly( N-isopropyl Acrylamide-co-3-sulfopropyl Acrylate Potassium Salt)Hydrogel and Its Properties

Lin Qiang He Jiang-chuan

2004, 32(1): 65-68,79.

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An advanced vehicle positioning technique in the intelligent traffic system had been investigatedputting stress on the principles and applications of the positioning system which combines GPS-DR with DAB-GSMgiving its main models and computing formulae and making a comparison of its characteristics．The results show thatto a certain degreeboth techniques meet the requirements of high precision and low cost despite their different applied fields．Howeverthe findings in the research on DAB-GSM will certainly carve out a brilliant future in the use of DAB and GSM networks for vehicle positioning techniques．

Application of Hybrid Self-excited Force Model to Time-domain Analysis of Wind-caused Buffeting of Long-span Bridges

Zeng Xian-wu Han Da-jian Su Chen

2004, 32(1): 69-74.

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To deal with the problem that the all18aerodynamic derivativesespecially part of cross and lateral aerodynamic derivativescan not be obtained from the wind tunnel experiment at presenta hybrid model of self-excited forces for the buffeting analysis of long-span bridges was presented．In this modelthe direct self-ex-cited forces are obtained by Y．K．Lin’s model and only a linear filter is used to simulate unsteady self-excited forceswhile the cross self-excited forces are extracted from the quas- i steady aerodynamic force model via Taylor expansion．It is a good choice to adopt the hybrid model proposed here when not all the aerodynamic derivativesespecially the cross aerodynamic derivativescan be obtained from the wind tunnel experiment．At lastan illustrative example was given about the Yamen Bridgewhich shows excellent agreement between the calculated and experimental results of wind tunnel adopting the aerodynamic elastic turbulence-field model for the whole bridge．

Information Fusion Methods for Vehicle Positioning System

Hu Yu-cong Zeng Yue Xu Jian-min

2004, 32(1): 75-79.

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An advanced vehicle positioning technique in the intelligent traffic system had been investigatedputting stress on the principles and applications of the positioning system which combines GPS-DR with DAB- GSMgiving its main models and computing formulae and making a comparison of its characteristics．The results show thatto a certain degreeboth techniques meet the requirements of high precision and low cost despite their different applied fields．Howeverthe findings in the research on DAB-GSM will certainly carve out a billiant future in the use of DAB and GSM networks for vehicle positioning techniques．

Experimental Study on Joints of the Concrete -filled Steel Tubular Column-beam with Ring Stiffeners

Su Heng-qiang, Cai Jian, Yao Da-xin, et al

2004, 32(1): 80-84.

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The mechanics behaviors of two joints of a concrete-filled steel tubular （CFST） column-beam with ring stiffeners were investigatedand the strain distributions of the beamthe steel tube shell and the ring stiffener were also analyzed．The specimens are all steel beams with different stiffener ribs among the rings．The experimental results show that the joints of this column-beam are characterized by their excellent mechanics perfor mance and high stiffnessthat the construction of stiffener ribs have little influence on their mechanics behaviorsand that the ribs can be regarded as elastic supports of the tubular beam with ring stiffenerswhich effec-
tively reduces the span of the hoop-beams．

Design Method for the Underpinning Structure Composed of Piles and Beams and Its Application

Huang Xiao-xu Zhu Ying-jun Huang Sui-huan

2004, 32(1): 85-89.

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In order to correctly design the underpinning structure composed of piles and beams in the pile-foundation underpinning project for the super -buildings of metroa standard and several measures to control the deformation of underpinning structure were proposed．On the basis of experimental results of 25specimensit was proved that the boundary plane between the new and the old concrete had obvious destruction foreboding and excellent protending performanceand a formula for calculating the bearing capacity of the boundary plane was established．Thereforethe calculating method for the bearing capacity and the deformation of underpinning struc-
ture were derived．The proposed designing method has been successfully used in the underpinning work of Guangzhou Metro Lines1and2．From the fact that all measured items met the controlling indices wellwhich proves the rationality of the designing method．

Wave-front Curvature Relation of Exciting Media Affected by External Field

Liu Shen-quan

2004, 32(1): 90-92.

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Through the moving coordinates and the perturbation analysis of boundary layer of wave frontthe linear relationship between the normal velocity and the wave-front curvature and the external fieldthat isthe Eikonal equation in external fieldwas obtained．The physical meaning of this relationship can be used to explain the Belousov-Zhabotional experimental phenomenon of spiral wave and scroll wave affected by external fieldwhile the geometric meaning of it is to give a theoretic method to determine the shape of wave-front boundary．

Some Notes on Fermat‘s Point

Lin Jian-liang

2004, 32(1): 93-95.

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Fermat’s problem is a famous problem which is of great practicality in engineering．The author presented a simple geometrical method of seeking Fermat’s point．The formulae for calculating the coordinates of the point were derivedwhich is expressed by the coordinates of the triangle apex．The conditions to generalize Fermat’s point were also derived．

Iteration of Holomorphic Self-maps in Classical Domain

Chen Wen-ge

2004, 32(1): 96-98.

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Proved here is the theoremthatif f is the holomorphic self-map in H（R _I ；R _I ） without fixed point in the first classical domain R _I and if f（B _nm ）⊂ B _nm each convergent sub-array of map cluster｛f _n ｝iterates at a point on the conjunct boundary of R I and B _nm where f _n is the nth iteration of f.

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