Table of Content

30 September 2004, Volume 22 Issue 3

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Articles

The Application of Control Lyapunov Function in Adaptive Control

CHEN Yi-mei, HAN Zheng-zhi, KOU Chun-hai

2004, 22(3):  269-272. 

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The problem of adaptive stabilization of a class of nonlinear systems with unknown parameters is considered. Employing the control Lyapunov function, an adaptive controller is designed to complete the stablization. The controller is robust to the uncertainties of both the parameters and the state of the system. It can also guarantee the adaptive stability of the closed loop system.

Performance of Generalized Soft Decision Metric Without Noise Variance Knowledge over Multipath Fading Channel

LI Qiang, BI Guang-guo, DU Peng

2004, 22(3):  273-278. 

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A new simplified soft decision metric, without noise variance knowledge, is derived in this paper. By recognizing that it is simply a distance metric in Euclidian space, we further generalize it to p-norm. Performance comparisons are presented for LDPC coded 16QAM/64QAM with different parameters. Simulation results show that, as compared with the simplified soft decision metric reported in ref.[6], there is no performance loss with our proposed generalized soft decision metric for both AWGN and multipath fading channel. Moreover, it is unnecessary to estimate noise variance at channel output, which greatly facilitates practical implementation. Further simulation indicates that, in multipath fading channel, a performance gain can be obtained with p a bit less than 2 at high signal to noise ratio.

A General Model for the Multi-valued BAM and Its Applications in IP Address Recognition

ZHANG Dao-qiang, CHEN Song-can, PAN Zhi-song

2004, 22(3):  279-282. 

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A general model for multi-valued bi-directional associative memory (BAM) is presented. It is based on the concept of similarity measure. From the general model, we can derive Wang's multivalued exponential BAM (MV-eBAM), the polynomial bi-directional hetero-corrector (PBHC) and several new multi-valued BAM models, such as the hyperbolic tangent BAM (HTBAM) and Caushy BAM. Among these models, we place special emphasis on the comparisons between PBHC and HTBAM. Simulation results show that the proposed HTBAM model has a competitive storage capacity and much greater error-correcting capability than the PBHC model. Finally, we apply the HTBAM to IP address recognition and obtain a novel algorithm for associative IP routing lookups.

A Fault Verification Method of the Rough Neural Network with Interval Numbers

HE Ya-qun, HU Shou-song, HOU Xia

2004, 22(3):  283-286. 

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A rough neural network method is proposed to solve the problems in an information system with interval numbers. The topologic structure and learning algorithm of the rough neural network are given, and the approximation theorem of the rough neural network is presented. Finally, to prove the feasibility of the method the rough neural network for fault verification of a fighter plane is constructed, and the simulation results show that the method is feasible and efficient.

A Study on the One-Time Pad Algorithm & Its Implementation

HUANG Yu-hua, HU Ai-qun, SONG Yu-bo

2004, 22(3):  287-290. 

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We have improved the security mechanism of WEP in wireless LAN and implemented the algorithm of one-time pad at less cost.It was illustrated that our method is more practical and simple in comparison with TKIP & Key Hopping. Though this scheme was designed for wireless network, it is also available for wired network, and its implementation will be easier.

Research on the Intellectual Data Model of the Geographic Expert System

FU Wei

2004, 22(3):  291-297. 

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This paper presents the design principle and realizable approach for the intellectual data model of the geographic expert system. With the frame network structure of knowledge, the author describes the entity units of geo-environment, and links the expression of expert knowledge at different levels with the pointer so that it becomes the frame network from knowledge to semantics. Also, the author expresses expert knowledge with extended R-F relational model based on intelligence, and discusses organizational structure of the knowledge base in the system and the design principle of inference engine. The data structure can be used to realize an integrated description for geographic entities and their interrelations, and the knowledge base of the system can be operated simply and easily with the model, and therefore, the inference mechanism can be assuredly realized. Taking Urumqi river basin as a test region, the author expounds the expression approach of the expert knowledge involved in the planning and decision concerning the rational use of land in the basin as well as the basic rules of expert knowledge expression and the organization models of expert knowledge in the system. Furthermore, the author also discusses the design principles and organization method of the inference rules and the inference algorithms of inference engine in the system.

An Improved Rake Receiver Algorithm of the CDMA System

ZHAO Jun-hui, WANG Dong-ming, YOU Xiao-hu

2004, 22(3):  298-302. 

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In order to suppress the multipath interference in the CDMA system, an improved Rake receiver based on parallel multipath interference cancellation technique (PMPIC) is proposed in this paper. The cause of multipath interference and multi-user access interference is first analysed. Next an improved Rake receiver is given a theoretical analysis and its simplification algorithm is also proposed. The PMPIC is studied by Monte Carlo simulation under different channel environments. Theoretical analysis and computer simulations illustrate that the improved Rake receiver can give significant improvement when compared with the conventional Rake receiver.

Blind Multiuser Detection Based on Linear Transform and MMSE for CDMA Systems

HU Yan-jun, FAN Qing-qing, ZHU Jin-kang

2004, 22(3):  303-307. 

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A blind multiuser detector based on linear transform and prediction for CDMA systems is proposed. It can eliminate MAI and ISI simultaneously. Using only the spreading sequences of the desired user, we first process the received signals by linear prediction. Next, MMSE detectors are obtained without explicit channel estimation. This avoids any channel estimation error, and the resulting method is more accurate.

Studies on Transmission Techniques of Layered Space-Time OFDM Systems

SU Peng-cheng, SUN Jun, ZHANG Ji-dong, SHI Cui-zhu

2004, 22(3):  308-313. 

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In this paper a layer and space-time coded OFDM system is proposed to provide a diversity gain for the MIMO channels and alleviate the frequency-selective fading effect. At the receiver, an algorithm of suppressing and cancelling interference among alyers is employed to overcome the interference among users and provide reliable communications with high data rate over wideband wireless channels. And this system can be used to transmit scalable MPEG-4 video. The simulation results show that the proposed system has good transmission performance in an environmnet with a moderate signal-to-noise ratio.

The Application of Genetic Algorithm in Randomizing Phase Feeding of Phased Arrays Sub-array Quantization

LIU hao, FAN De-sen

2004, 22(3):  314-317. 

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In Iarge scale phased arrays, we apply the sub-array technique to reduce the number of expensive digital shifters. But new problems will arise when it comes to sub-array phase quantization——which phase should be chosen? The former or the later element? All this makes the analysis of sub-array phase quantization more complicated. On the basis of sub-array quantization randomizing phase feeding, we use genetic algorithm to optimize the randomizing phase feeding and give an optimization example, in which a good result is obtained.

A Novel Background-Hue-Based Shot Boundary Detection Algorithm

LEI Zhen, WU Ling-da, LAO Song-yang

2004, 22(3):  318-321. 

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A background-color-invariable-based improved twin-histogram algorithm is presented to detect shot boundary in this paper. Firstly, a fourth-orders statistic hypothesis testing in inter-frame difference is used to separate background from a general video sequence. Secondly, (L^*a^*b^*) color model is used to calculate the hue in the background areas. Lastly, the improved twin-histogram algorithm is used to detect shot boundary. This method needs fewer calculations and has a higher precision ratio. The experimental results show that the method is more accurate and effective in shot detection than other algorithms.

The Application of Color Constancy to Color Image Enhancement

HUANG Kai-qi, WU Zhen-yang, WANG Qiao

2004, 22(3):  322-326. 

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As an important brightness and color visual theory, Retinex theory has received more and more attention in recent years. We apply it to color image enhancement. Basing on the analysis of MSRCR algorithm, we make use of the histogram of image itself to improve the problem by the GW assumption and choose the parameters adaptively. The experimental results confirm the effectiveness of our algorithm in color image enhancement and the images processed get better rendering by human visual systems.

Blind MIMO Equalization Algorithm for Row Diagonally Predominant Channel Matrix

LIU Qian-lei, YANG Lü-xi

2004, 22(3):  327-331. 

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An equalization algorithm based on the elementary matrix transformation is proposed for the MIMO communication channel, and the corresponding blind equalization algorithm is obtained for the row-diagonally-dominant MIMO system. This algorithm diagonalizes the MIMO channel matrix based on the statistics of the source signals by using the elementary matrix transformation in mathematics. The application of this blind equalization algorithm in ordinary MIMO system can eliminate the parameter estimation deviation of the ordinary MIMO equalizer because of sudden interruptions etc. and improve the BER performance of the system. Simulation results demonstrate that the proposed blind MIMO equalization algorithm has excellent performance both in equalizing the row-diagonally-dominant channel matrix and the elimination of the parameter estimation deviation of the ordinary equalizer.

A Predictive Function Active Control Applied to Suppressing the Vibration Responses of Elastic Linkage Mechanisms of High Speed

LI Peng-fei, LIU Hong-zhao, YUAN Da-ning, SHAN Ning

2004, 22(3):  332-336. 

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The paper first applies the predictive function control(PFC) law to deal with the vibration active control of elastic linkage mechanisms of high speed by using the system discrete state-space equation. The reference track、base functions and constrain condition of voltage are chosen according to the characteristic of the dynamic responses of mechanism and actuator material. Through optimizing weight coefficients of base functions, the output control voltage is reached. The simulation results indicate that the PFC based on the simple model is effective for reducing the vibration amplitude of elastic linkage mechanisms of high speed,the maximum feedback control voltage required in the PFC is further reduced as compared to the optimal pole assignment control law. Meantime it can satisfy the real-time demand.

Fractal Based Feature Extraction of Cutting Force and Its Application in Tool Wear Monitoring

ZHENG Jian-ming, LI Yan, XIAO Ji-ming, HUANG Yu-mei, HONG Wei

2004, 22(3):  337-341. 

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The paper presents a new method of describing signal complexity using fractal dimension according to the change characteristic of the cutting force in the drilling process. From the point of view of engineering application, it introduces the algorithm of box dimension and information dimension for discrete time series and reveals the inherence relation between the fractal dimension and signal complexity by calculating the fractal dimensions of three simulating signals. It also researches into the changing rules of the fractal dimension in the whole course of tool wear through experiments. The results show that along with the increase of tool wear, the fractal dimension of the cutting force signal assumes the falling trend, and the tool wear monitoring can be realized effectively by using the fractal dimensions as the feature of the cutting force signal.

A Research on the Estimation of Harmonics of a Non-circular Arc

ZHAO Qian-cheng, DENG Shan-xi, LIANG Fa-yun

2004, 22(3):  342-346. 

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The harmonic characteristics of a circle profile can be estimated by FFT,which, however, cannot be used in the case of a non-circular arc because the sampling points around the whole circle cannot be obtained this way. In this paper, a harmonic model of a circular arc based on RSM (response surface method) is built up; the morbidity of the model is studied; and the method to improve the model is advanced. By means of interpolation and iteration, RSM is combined with FFT to estimate the harmonic characteristics of a circular arc. As harmonic characteristics are formed in the manufacturing process and affect the performance of the work pieces and the measuring uncertainty, our research in this regard is of considerable importance to other researchers in the same field.

Reliability-Based Optimization of Coil-Tube Springs Based on Incomplete Probability Information

ZHANG Yi-min, HE Xiang-dong, LIU Qiao-ling, WEN Bang-chun

2004, 22(3):  347-350. 

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The probabilistic perturbation method and the Edgeworth series technique are employed to devise a practical and effective method for the reliability optimization design for coil-tube springs with non-normal distribution parameters on condition that the first four moments of basic random variables are known. The respective program can be used to obtain the reliability optimization design information of coil-tube springs with non-normal distribution parameters accurately and quickly.

The Sliding Mode Variable Structure Control for the DC-DC Buck Converter

XIAN Yan-hua, LUO Xiao-shu, LIANG Zong-jing, WENG Jia-qiang

2004, 22(3):  351-355. 

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Using the theories and methods of sliding mode control, the variable structure controllers are designed to control chaos in DC-DC Buck converter by means of direct and indirect control. Some desired output voltages are obtained using this control method. The correctness and effect of this method has been confirmed by theoretic analysis and numerical simulation.

An All-Digital BIST Scheme for the ADC Test

RAO Jin, WU Guang-lin, LING Ming, HU Chen

2004, 22(3):  356-359. 

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In this paper, a new built-in self-test approach has been applied to testing on-chip AD converters. A ramp signal is used as test stimulation. This test circuit is capable of measuring the offset, gain, integral nonlinearity(INL), and differential nonlinearity(DNL) errors by testing the low bits of ADC. Simple structure, and high speed are the advantages of the proposed test structure.

The Design of the On-Chip Voltage Reference in the 10bit 40MSPS Analog-to-Digital Converter

WU Jian-hui, YUAN Wen-shi

2004, 22(3):  360-364. 

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The on-chip voltage reference in 10 bit 40MSPS ADC has been designed. It features high precision, small area, etc. The band-gap reference is used for its basic configuration. Other innovations include a novel type CMOS operational amplifier with high gain, a wide input range with a view to improving the reference precision and two group voltage references RET and REB, the difference between which acts as the comparative voltage reference to reduce the reference absolute error. The Hspice simulation with Chart CMOS 0.35 μm shows that the op-amp gain is 88 dB, that the standard deviation of the voltage reference is lower than 5 mV and that the temperature coefficient is lower than 10^-4/(℃). The testing result shows that the designed voltage reference can meet ADC need after taping out.

A Research on Dynamic Access Control Technology in the Distributed Manufacturing System

HA Jin-bing, HU Wen-bin, YAN Yang-guang

2004, 22(3):  365-369. 

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The traditional access control mechanism in a distributed cooperative work system is static and lacks flexibility. So a new access control method called dynamic access control is introduced here. It combines the workflow management with access control matrix to improve the flexibility and efficiency. How access rights can be derived from a Petri net workflow is discussed in this paper. Access rights are granted according to the state of the workflow. The concept of workflow is defined by Petri nets which offer a solid mathematical foundation. Finally the method is implemented in a collaborative project discussion process of a cooperative work system called eCWS.

Blind Signal Separation by Kurtosis

YE Jun, LIU Feng, XU Bo-ling

2004, 22(3):  370-374. 

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Blind source separation is an interesting project in the field of signal processing and has a wide development and application prospect. Independent component analysis is one of important methods of blind signal separation, so a kurtosis maximization/minimization-based blind signal separation method is considered in this paper, and the mixture of signals is limited to be instant(non-convolutive). Firstly, the basic theory of separation is introduced, and then the detail of our algorithm is presented. The method is applied to the separation of mixed speech signals and mixed image signals. The results of experiments prove that the advantage of this algorithm is good performance of separation and fast convergence through simple computation.

A Study on the Fire Retardance Properties of Cellular Aluminum Alloy

LI Jie-feng, HE De-ping, YU Kun

2004, 22(3):  375-379. 

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Fire retardance limit is used to evaluate the fire retardance properties of cellular aluminum alloy. The temperature field and fire retardance limit are solved by finite element analysis. Cellular aluminum alloy has outstanding heat resistance properties. At the temperature of 660(℃)(a few degrees above the melting point), the fire retardance limit of a 26 mm thick plate made of cellular aluminum alloy with 76% porosity, is increased to infinity, and its shape does not change. In order to allow the temperature of unexposed surface to reach the melting point, the heating temperature would have to be raised. When the cellular aluminum alloy is heated above 710(℃), volume shrinkage occurs and the ratio of volume shrinkage increases with the temperature.

The Tree-Structure Algorithm for the Elimination-Reduction of Air-Column-Inherent Frequency in the Multi-degree-of-Freedom Piping System

LÜ Lin-tao, CUI Du-wu, LÜ Hui

2004, 22(3):  380-383. 

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Based on such theories as wavelet analysis, applied mathematics and data structure, the tree-structured geometrical model and algorithm for the elimination-reduction of air-column-inherent frequency were proposed in order to avoid resonance between the air-column-inherent frequency of the multi-degree-of-freedom piping system and the mechanical-inherent frequency. By applying the software system based on this algorithm to the fluctuation analysis of a piping system, it was found that its calculation coincide with the experimental results very well. Therefore, it has both theoretic and practical value to the designing of a new piping system and the rebuilding of an old one in petroleum, chemical and electric power industries.

An Improved Back-Propagation Neural Network Algorithm

QIU Hao, WANG Dao-bo, ZHANG Huan-chun

2004, 22(3):  384-387. 

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Based on the idea of standard back-propagation(BP) learning algorithm, an improved BP learning algorithm is presented. Three parameters are incorporated into each processing unit(PU) to enhance the output function. The improved BP learning algorithm is developed for updating the three parameters as well as the connection weights. It not only improves the learning speed, but also reduces the occurrence of local minima. Finally, the algorithm is tested on the XOR problem to verify the validity of the improved BP.

The Structure of the Immunocontroller Based on RBF Neural Networks

ZHANG Zheng-dao, HU Shou-song

2004, 22(3):  388-391. 

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Basing on the course of immunity mediated by T lymphocyte, we have constructed a new controller structure based on the immune feedback mechansim of biological immune systems by simplifying the mathematical model of the immune mediated by Tlymphocyte and using the RBF neural network. We used positive feedback to simulate the process of immunologic enhancement for improving the speediness of the system and used negative feedback to simulate the process of immunological suppression for improving the stability and robustness. As a feed-forward controlled of a kind of affine nonlinear systems, the stability was proved in this paper. Computer simulation results demonstrated that the suppression ability of the controller against the system's noise is satisfactory.

The UML Class Diagram Coarse-Grained Slicing Based on Dependency Analysis

WU Fang-jun, YI Tong

2004, 22(3):  392-397. 

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The unified modeling language (UML) is an intuitionally standard modeling language, which captures related decision and understanding for the modeled system. It can be used in different processes of developing systems, and has gained extensive support from industrial circles. However, because it has assimilated too many object-oriented methods and technologies, it is complex and contains too much useless information. Moreover, it is difficult to understand and analyze the UML. Now how to understand, analyze, test and maintain the systems modeled by UML has become the key to using the UML. For this reason, we introduce the concept of program slicing into one of the most important static behavior-specifying mechanism of the UML-the UML class diagram. Firstly, the paper defines some kinds of dependency among classes. It then constructs the UML class dependency graphs to represent all kinds of dependency by translating the UML class diagraph to dependency graph. Basing on these models, the paper proposes methods to the UML class diagram coarse-grained slicing. Finally, this method is described in detail through an example. Results show that the UML class diagram coarse-grained slicing can provide the same benefit as the slicing of programs, namely reduced length, thus leading to ease of comprehension and future maintenance. In a word, the method we have devised is highly efficient.

A Study on the Preparation and Performance of NPG/Montmorillonite Composite Materials for Energy Storage

YU Shao-ming, JIANG Chang-long, CHEN Tian-hu

2004, 22(3):  398-401. 

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The preparation and phase change kinetics of NPG/montmorillonite composite materials for energy storage were studied. XRD、IR and DSC have been used to characterize the structure and test the property of energy storage and phase change velocity. The results showed that it has comparatively greater phase change velocity, weak plastic crystal weightlessness and larger phase change enthalpy. It is a new type organic-inorganic nano-composite materials for energy storage which has the latent heat storage property of NPG and the obvious heat storage and filling property of montmorillonite.

The Simulation Research on the Effectiveness of the Windproof Walls Built in Open-Air depots for Building Materials in Shanghai Areas

REN Yi-min, ZHANG Xu, SHA Gao-yuan

2004, 22(3):  402-406. 

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Basing on the numerical simulation of the windproof walls built in open-air depots for building materials, this paper analyses the velocity of natural wind and how the width and the height of the windproof walls help in preventing the material particles from being raised.

The Convergence of the Abstract Evolutionary Algorithm Based on a Special Selection Mechanism

XUE Ming-zhi, ZHU Xiu-ge, JIAO Li-cheng

2004, 22(3):  407-410. 

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evolutionary algorithm. In this paper, the definition of the abstract selection and evolution operators is given. The abstract evolutionary algorithm, which describes the evolution as an abstract stochastic process composed of these two fundamental abstract operators is defined. In particular, a kind of abstract evolutionary algorithms based on a special selection mechanism is discussed. According to the sorting of the state space, the properties of the single step transition matrix for the algorithm are analyzed. Finally, we prove the existence of the limit probability distribution of the Markov chains.

Radial Basis Function Networks Based on Wavelet Analysis for the Annual Flow Forecast

JIANG Xiao-hui, LIU Chang-ming

2004, 22(3):  411-414. 

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In this paper, radial basis function networks based on the wavelet analysis method is introduced to forecast hydrologic time series. Firstly the hydrologic time series is decomposed to different frequency components with wavelet analysis. Then the artificial neural network is used in multi-scale forecasting of these coefficients. Finally, based on the formula reconstructed, the forecasted hydrologic time series is obtained. The effectiveness of this method is verified by an example.

The Implementation of the Audio Module in Embedded System

ZHU Min, XU Guo-zhi

2004, 22(3):  415-418. 

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With the development of high-performance embedded processors and high-integrated hardware circuits, the embedded system is widely used on PDA like products. This paper presents a low-cost, low-power and high-performance method of designing the audio module in embedded systems, and the detailed implementation of the method is based on Jingwei Board (an embedded experimental platform based on Intel StrongARM SA-1110).

The Dimensionless Representation of Collection Efficiency of Cyclones

ZHANG Xiao-ling, KANG Yan-ming, FU Hai-ming

2004, 22(3):  419-422. 

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The effect of Reynolds number and Stokes number on particle motion and separation is discussed by analyzing the hydrodynamic behaviors of aerosol particles in reverse flow cyclones. Experimental data in the classical literatures are used as the basis of the regression analysis, and a new semi-empirical expression, which contains the two dimensionless parameters, is presented for calculating the grade efficiency of the cyclones.