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

Noisy Multiuser Performance of Coherent DCSK Chaos Communication Systems

Wang Guang-yi Qiu Shu-i sheng Ma Za-i guang

2003, 31(12): 1-4.

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In order to give a quantitative description of the noisy multiuser performance of digital communications using chaosa new approach is proposed to analyze the noisy multiuser performance of a coherent DCSK system in this paperbased on discrete-time chaotic sequences．The expressions of error performance and its upper bound for multiuser and single user are given theoretically and verified by the simulation results．Theoretical and simulation results show that the noise performance is reduced rapidly by increasing the number of the mult-i userand that there is a bound for noisy multiuser performance of coherent DCSK．The approach to increasing the performance is to produce a set of orthogonal chaotic signals．

Numerical Simulation of Interaction System Between Monopole Handset and Layered Human Head Model

Zhou Xiao-ming Lai Sheng-Li

2003, 31(12): 5-8.

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The SAR（Specific Absorption Rates）distribution in human head emitted by a monopole antenna handset was simulated using the finite-difference-time-domain （FDTD） method with a three-layered human head model at the frequency of900MHz．The feasibility of the calculating method was proved by the comparison with experimental results．The calculated results show that SAR and the absorption rate of power increase when reducing the length of antennaand the absorption energy can be more above half of the total radiation energy．The peak and the average SARs of teenager are more than those of adult in the human head model．The average SAR （0．112W／kg） of teenager exceeds the IEEC95．1— 1991limit （0．08W／kg） when the monopole length is λ／4which means the harm of handset radiation to teenagers is more serious than that to adults．

Realization of GSM Network Short Message Wireless Communication SCADA System

Zhu Ning-xi Zhang Qi

2003, 31(12): 9-12.

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The formation and application of a supervisory control and data acquisition （SCADA） system of wireless communications was discussed．The basic configurationwork principles and main functions of the periphery RTU were all analyzed．In this systemthe RTU collects the data of the processing sewage and sends the data to the supervise-control center by Short Message．The supervise-control center controls the RTU with Short Message．When a fault occurs in the RTUthe supervise-control center transmits the message to the RTU maintenance man via Short Message．

System Level Design and Implement of USB Interface IC with Parallel Bus

Liu Wen-ming Cai Min Li Zheng-lin

2003, 31(12): 13-16.

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Based on USB1．1specificationsthe system level design of USB interface IC with parallel bus was discussed．Its state machine design and conceptual block diagram were described．The key functions and their implement cases and methods were presented．The success tapeout result within design specifications was given and its advantages such as high performance-price rate and abroad application fields such as imagingmass memory and communication devices were explicated．

Mixed Seria-l parallel Mult-i user Detection Algorithm in Fading Channels

Wang Zheng-mao Y e Wu, Feng Sui li et al

2003, 31(12): 17-21.

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A new mixed seria-l parallel mult-i user detection algorithm with decision feedback was proposed on the basis of RLS algorithm．Theoretical analyses of the new algorithm in fading channels were carried outwhere the system data transfer rates were divided into two cases： one is related to ISIthe other is not．A theoretical formula for BER （Bit Error Rate） calculation was then presented and the simulation of the algorithm was performed．The results show that the algorithm proposed here is of high correctness and low BER with low costthus making the algorithm practicable．

Virtual Instrument Software Realization in Ethernet Intelligent Measuring and Control System

2003, 31(12): 22-25.

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Based on the present new trend of Ethernet intelligent measuring and control systema general system platform structure of Ethernet intelligent measuring and control was proposed．The design and the main function module of networked measuring and control virtual instrument software based on Java were presented in detail．A virtual instrument platform software was realized．It is found thatthrough the proposed methodthe feasibility and flexibility of the platform software can be enhanced and the effectiveness in the process of measuring and control system designing can be improved．

Elevator Traffic Flow Analysis Based on Artificial Immune Clustering Algorithm

Li Zhong-hua, Zhu Y an-fei, Li Chun-hua, et al

2003, 31(12): 26-29.

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By employing an artificial immune clustering algorithmthe elevator traffic flow in a certain building during one week was analyzed．The promotion and suppression mechanisms of artificial immune algorithm were exploited to compress the original elevator traffic flow data collected in5minand a distinct elevator traffic flow memory dataset was obtained．The memory dataset was then classified on the basis of two methods： the Minimal Spanning Tree and the Minimal Distance Method．The result of classification clearly reveals the real feature of elevator traffic．Thereforethe approach addressed here may provide a powerful theoretical support for elevator group control．

Method of Straight Line Edge Subpixel Localization for Mechanical Part Image

Y ang Min, Y e Bang-yan, Mou Li, et al

2003, 31(12): 30-33.

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Based on practical application of computer vision for mechanical parts geometry parameter inspectiona new approach is presented to determine the ramp edge at the level of pixel using Laplacian of Gaussian （LOG） function．The pixel level edge to subpixel accuracy is then located by using the MLS linear regression on the condition that the model of the edge is known．Contrastive experiments have been conducted to test the algorithm of the spatial moment subpixel localization for the straight line edge and the algorithm proposed in this paper．The experiment results show that the precision of two algorithms is satisfactory and the velocity of the MLS linear regression subpixel localization is faster．

A Quick Intelligent Algorithm for Examination Paper Generation

Xiong Y un-hui, Xiao Ren-yue, Tian Xiang

2003, 31(12): 34-36,41.

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According to the demand of the examinerrelevant information was collected for the item bank according to the basic contents of learning．Thusa unique method of collecting testing resources and the concept of item risk were proposed．Firstlywe found an index that had the minimum resource relative to the demand of examiner．Thenwe searched for all the items from the item bank that satisfied the indexand chose a minirisk item．We repeated doing this till the examiner was met．The algorithm showed good performance in speed and qualityand provide a good method for the large scale net-examinations．

Simulation of Expert Self-adaptive PID Control System for Brushless Doubly-fed Machine

Chen Zh-i wei, Y ang Xiang-yu, Shen Hu-i yang

2003, 31(12): 37-41.

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The application of expert self-adaptive PID controller in Brushless Doubly-Fed Machines （BDF M） for adjustable speed drive was presentedthe simulation model of the control system based on MATLAB／Simulink was also establishedthen the simulation experiments under the conditions of startup and steady-state were carried out．The results show thatcomparing with open-loop conditionthe static and dynamic performances of the system are improved greatly by using the controllerand the overshoot of the machine decreases when the rotating speed or the load changes．The scheme proposed here is a simple and convenient closed-loop control strategy for BDF M drive．

Realization of Process Control System for Lithopone Kiln and Calcinator

2003, 31(12): 42-45,50.

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To improve the low and unstable quality of the lithopone product under manual control in Guangzhou Lithopone Factory, a computer control system is introduced to control the running of the key device-Lithopone Kiln and Calcinator. A two pole control scheme is adopted on the basis of full analysis of the on spot conditions: at one pole, it applies an anti saturation PID arithmetic to control the head kiln temperature so as to keep the energy supply stable; and at the other pole, it adopts a control scheme based on the concept of energy to control the specifications of achromic ability so as to improve the quality and keep it stable. After eight month on spot application and evaluation, the head kiln temperature is controlled within the range of the given value±5 ℃, and the high quality product rate is increased by more than 30% .

An Improved Spectrophotometric Procedure for the Laccase Assay

2003, 31(12): 46-50.

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An improved spectrphotometric procedure for laccase assay is presented in the paper.The spectrophotometer,which was the product of the Japanese SHIMADZU company, was used to record continuously the time course curve of the laccase catalyzed reaction at the wavelength of 420 nm at 25 ℃ with ABTS[2,2′ azino bis (3 ethylbenzothiazoline 6 sulphonate)] as the substrate to measure the initial velocity. And the optimum pH for the laccase sample A or B was 4.0 or 4.5 in Britton Robinson buffer(0.04 mol/L) at 25 ℃,respectively. The two most significant parameters in the Michaelis Menten theory, the Michaelis constant K m and the maximum Michaelis Menten velocity V max , were determined from a Lineweaver Burk plot. The K m for the laccase A or B was 6.64×10 -5 mol/L or 2.21×10 -5 mol/L,respectively.And V max for the laccase A or B was 1 425 μmol∕(L·min) or 325 μmol∕(L·min),respectively. The laccase A or B was recommended to dilute for a hundred thousand times with Britton Robinson buffer of optimum pH at 25 ℃ because the time course curves for the laccase A or B was linear within 4 minutes.

Preparation of Chitosan Grafted by Vanillin Under Microwave Radiation and Its Adsorption Property

2003, 31(12): 51-53,62.

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Chitosan was grafted with vanillin under microwave radiation. The product was characterized through IR and XRD and its adsorption property was investigated. The result indicated that the rate of the reaction of chitosan modification was greatly enhanced under microwave radiation. The grafted chitosan had a higher adsorption capacity and adsorption speed for metal ions than the unmodified chitosan. Under normal temperature, the former's adsorption capacities for Cu 2+ , Ni 2+ , Zn 2+ , Pb 2+ were 195.5, 107.7, 143.7, 97.5 mg·g -1 respectively, and its adsorption for metal ions could be saturated in 2 hours.

Effect of Alkali-metal Ions on Removing OH Groups from Erbium-doped Phosphate Glasses

2003, 31(12): 54-57.

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According to the influence of OH - on the fluorescence lifetime of Er 3+ in glasses, the relations between the type/content of alkali metal ions and the content of OH - groups in erbium doped phosphate glasses were studied. The results show that, by bubbling dry O 2 and CCl 4 into the glass melt, the amount of OH - groups can be effectively reduced. At the initial stage, OH - groups were removed rather rapidly, then the process slowed down, and finally OH - groups were removed and absorbed, and reached an equilibrium. The fluorescence lifetimes of all samples with different alkali metal ions(Li +, Na + and K +) were compared, which shows the decrease of Er 3+ fluorescence lifetime with the increase of alkali metal ion diameter and O 2- volume in the glasses. It is also shown that increasing the amount of alkali metal ions would reduce the lifetime of Er 3+ , which means more OH - groups would remain in the glasses.

Separation of Butanol-Acetone-Water System Using Repulsive Extraction

2003, 31(12): 58-62.

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The repulsive extraction is proposed to separate butanol and acetone from water. In order to reduce energy consumption in the separation, NaAc,MgCl 2,Na 2CO 3 and other salts are added in the process to form composite extractant, which can obviously change the mutual solubility of butanol acetone water system at room temperature. The composite extractant can greatly increase the distribution coeffecient and selectivity coefficient. The effect of the operation parameter on separation is further studied. Preliminary heat balance shows that the new separating method can save 30.4% energy compared with the traditional method.

Measurement and Analysis of Residual Stress in Link Using Shot Peening

2003, 31(12): 63-65.

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In order to compare the magnitude of residual compressive stress in links caused by the rolling throw ing pills machine and the hanging throwing pills machine, the residual stresses were measured using strain gauge rosette by the drilling method. The result shows that shot peening can be used to cause residual compressive stress effectively, and that the residual compressive stress caused by the hanging throwing pills machine is higher than that caused by the rolling throwing pills machine. The cause of residual stress errors was also discussed.

Impact Experiment of Semirigid Guardrail System Model

2003, 31(12): 66-70.

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Based on the Instron 9250 dropping hammer impact system, an impact system for the modeling test of highway guardrail system (including W beam, blocks and posts) was designed and implemented. Based on this system, impact experiments of guardrail system were carried out. The dynamic behaviors of the guardrail system under impact were fundamentally acquired and the features of the deformations of each component of the guardrail system were described. The deformation energy of W beam and block was calculated from the experimental results and their contributions to the energy absorption were investigated. lt was found that the energy absorbed by W beam accounted for about 50%～65% of the total absorbed energy and the energy absorbed by blocks accounted for 15%～25%.

Design and Application of Reinforcement Program Based on Finite Element Analysis Result

2003, 31(12): 71-74.

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Using the object oriented program language Delphi, a program is developed to treat the result of the finite element program SAP84 for getting the reinforcement according to the new code. An efficient data structure is established to save the system memory. Two calculated methods are used to overcome the inconsistency of the different restrictions. To enhance the user's working efficiency, a function is added to hint the users why the result of calculation is beyond the restriction.

The most Economical Control in Managerial System

2003, 31(12): 75-80.

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Based on the conception of the most economical control problem and its limitation for the undefined mathematical models, a new model and definition for the implementation of the optimum or most cost effective ratio of function and quality control over cost control was proposed at the prerequisite satisfying the essential system requirements. The most economical control problems in this field of management system reliability, ABC management method and WSR method, such as the cost of reliability, running cost and the optimal benefits, were explored and studied.

Boundary Layer of Reactive Flows in Porous Media

2003, 31(12): 81-83,85.

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The property of reactive flows in porous media was discussed. With the help of perturbation method of inner and outer solution, the linear relation between the change of normal velocity, normal gradient, gradient of diffusion, gradient of infiltration and curvature and the change of concentration, the pressure induced by the change of porosity were all analyzed. The diffusion equation describing central boundary was thus obtained in theoretical method.

On Jones' Problem Concerning Binomial Coefficients

2003, 31(12): 84-85.

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Let n be a positive integer.J.P. Jones conjectured that if n>3 and ( 2n-1n)≡0 ( mod n 3 ), n is an odd prime. In this paper, using some elementary methods of number theory, the author proves that if n is even, there is ( 2n-1n) 0(mod n 2 ), wnich means that Jones' conjecture is true for even integers n .

Solution to a System of d'Alembert Functional Equations

2003, 31(12): 86-88.

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In the present study, the solution to the d'Alembert type functional equation f(xy)+f(xy -1 )=f(x)g(y)+h(y) is extended to the study of a system of d'Alembert functional equtions on a group under the condition that the former satisfies f(xyz)=f(xzy) .For this purpose, a new function is introduced and the system of functional equations on a group is decomposed into independent equations. A new symbol is used to show the general solution to a system of functional equations on a group.

Turbulence Intensity of Bend Flow

2003, 31(12): 89-93.

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This paper presents an experimental study on the flow characteristics of the bendway on the hydraulic smooth plane by means of the advanced three dimensional acoustics Doppler current meter. Time average velocity and fluctuating intensity are measured from all aspects. The turbulent characteristics of bend flow are analyzed and a mathematical expression of the relative turbulent intensity along longitudinal direction is acquired. In addition, the distribution characters of longitudinal, lateral and vertical turbulent intensities are compared.

Construction of Regional High Technology Industrialization System

2003, 31(12): 94-98.

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Though the success of Silicon Valley benefits from many exterior conditions, it has not been exceeded by other science and technology parks with exactly the same conditions as yet. The success of Silicon Valley, to a great extent, attributes to the high technology industrialization system, which is the core competence of Silicon Valley. The high technology industrialization system is generally composed of innovation system, industrialization system and industrialization supporting system. Only the three systems collaborate closely could the high technology industrialization process be smooth. If we want to develop the high technology industries in our country, we should focus on the construction of the high technology industrialization system.

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