Table of Content

30 June 1998, Volume 16 Issue 2

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Articles

Study on Vibration Characteristics of Micro-Displacement Actuactor

WEN RENLIN, YAN JINGPING, QIU XIAOHAN

1998, 16(2):  127-132. 

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Micro-displacement actuator for ultrasonic vibration cutting is designed. The vibration characteristics and matching circuits are analyzed. Experimental results prove that the theory analysis are right. This actuator can also be used to error compensation or precision cutting.

A Cascade Design of Digital Bandpass Filter

WAN WANGGEN, YU XIAOQING

1998, 16(2):  133-139. 

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A prototype ⅡR digital bandpass filter is derived from an analogous bandpass filter by using bilinear transformation. The formulas relating the digital bandpass filter's coefficients with its center frequency and bandwidth are obtained. Using N sections of such digital bandpass filter, a cascade ⅡR digital bandpass filter is constructed. Based on the specifications and the formulas given, the parameter N and bandwidth of prototype ⅡR digital bandpass filter can be obtained, and the unknown cascade ⅡR digital bandpass filter can be finally determined. The filter has few coefficients and a simple structure and it is easy to be designed. It is especially suitable for its implementations when using DSP.

On the Asymptotic Analysis of Cramer-Rao Bound for Time Delay Estimation

YIN CHENGYOU, XU SHANJIA, WANG DONGJIN

1998, 16(2):  140-148. 

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ln this paper, starting with the most elementary probability formula of Fisher matrix for time delay estimation, a rigorous asymptotic expression of Fisher matrix for time delay, Doppler shift and its higher derivative joint estimation is introduced by using the asymptotic equivalent property of Toeplitz matrix, circulant matrix, and the specrtum characteristic of circulant matrices. The present result is more accurate than the commonly used one. A comparison between the two results shows that under certain conditions the agreement of the two results is excellent.

Viterbi Decoding Algorithm and Its FPGA Implementation for K=9 Convolutional Codes

HU AIQUN, PANG KANG, SU JIE

1998, 16(2):  149-156. 

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This paper deals with the error control problem in digital mobile communications. The scheme which employs the maximum likelihood Viterbi algorithm for decoding the K=9 convolutional data is studied. In this scheme, some efficient methods such as the in-place modification operation for path metrics, the saving of path transition and the circle access for path surving are presented. By using these methods, the RAM size needed for saving metrics and paths and the power consumption are decreased. It is shown that the Viterbi algorithm of K=9 whose performance specifications satify the IS-95 standard can be implemented with a single chip FPGA XC4010. The performance is tested, and the implementation consideration is discussed.

A Beeper Intermodulation Distortion Analysis Using Volterra Series

LIAO XIAOPING, WEI TONGLI

1998, 16(2):  157-162. 

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We study the third-order intermodulation distortion of a radio frequency receiver in a Beeper with Volterra series analysis. For a cascaded system, we have deve loped a Volterra model for individual circuit of the receiver. We also have studied the relation between the third-order intermodulation distortion of the overall radio frequency receiver and that of the individual circuit. The calculated results are desired for designing the radio frequency receiver, and can be used in other weakly nonlinear distorted receivers.

The Algorithm of the Wavelet Network for Nonlinear Function Approximation

LIU HONG, MO YULONG

1998, 16(2):  163-169. 

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In this paper, we use a new type of network, wavelet network, to approximate a nonlinear function. The wavelet network is studied with the combination of the traditional neural network theory with the most advanced math tool of analysis and it contains wavelons whose activation function is wavelet constructed with sigmoid function. This paper illuminates the approximation theory of the wavelet network and constructs a practical wavelet network. We also discuss the choice of the mother wavelet and the algorithm of decreasing the number of wavelons. The experimental results show that the wavelet network has achieved a high accuracy for approximating nonlinear function, and the scale of the network is small.

Application Research of Finite Element in Electrical Capacitance Tomography

XIAO HUA, YAN JIE, BAO ZONGTI

1998, 16(2):  170-175. 

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This paper discusses the application of the method of finite element in capacitance tomography, and describes an emulation software package for capacitance tomographic image reconstruction which is based on 12-electrode capacitance transducers. It is developed on SGI graphic workstation using visualized programming language PV WAVE. With the help of it, we can study in depth the variations of capacitance sensitivity distributions and fluid model parameters. Hence, it provides powerful methods for improving image reconstruction algorithm and the design of optimal capacitance transducer geometrical parameters. Finally, by using the emulation results, the properties of capacitance tomography are discussed.

The Influence of External Magnetic Field to the Energy-Flow Deflection of Magnetostatic Surface Wave on Anti-Ferromagnetic Films

YU LIMING, WANG QI

1998, 16(2):  176-184. 

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The dispersion relations of magnetostatic surface wave, which has higher and lower frequency branches, on an antiferromagnetic plane surface are studied in the case that the bias magnetic field is oriented arbitrary within the surface of the antiferromagnet. It is show that the direction of the energy flow of two branches of the wave are sensitive to the direction and amplitude of the bias magnetic field, and can be controlled to deflect up to 90 degrees.

A Study on the Boundaries of Diamond Growth Region Under Activated Low Pressure Conditions

WAN YONGZHONG, ZHANG WEI, WANG JITAO, HUANG ZHONGQIANG

1998, 16(2):  185-190. 

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Based on the non-equilibrium thermodynamic coupling model, the ternary C-H-O stationary non-equilibrium states phase diagrams are calculated under different temperature and pressure in this paper. The calculated results of the isothermal sections show that the whole diamond growth region will gradually rotate anti-clockwise around its core with the substrate temperature increasing while its shape changes greatly.

A Study on Adsorptive Theory of Real Gases

YANG QINGXIAN, LU XUEDONG

1998, 16(2):  191-199. 

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In this paper, the adsorption is studied in the light of statistical mechanics, with the result that a universal isotherm equation of the adsorption has been found, and the practical isotherm equation for real gases is given when the interaction between gas molecules is depicted in terms of Keesom and the Lennard-Jones potential. The experimental isotherms of the adsorption of medium and micro aperture charcoal are measured. It is seen that the agreement between theoretical and experimental isotherms of micro aperture charcoal is satisfred.

Research on Generating Mechanism of Engraving Graphics with Set and Random Fractal

DENG ZHONGLIANG

1998, 16(2):  200-208. 

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The generating methods of engraving graphics with set or random fractal are put forward in this paper.The engraving graphics can be controlled by the original fractal model,rules of fractal, translation and mapping.With mapping method,the engraving graphics on a plane can be translate into a trimensional graphics on an object with a complex surface.Because of the self-similarity,fine structure and iteration of the fractal,the stored information quantity for graphics can be reduced.Our methods can be used to generate the tool path for engraving and get a good artistic style.

Building of Fuzzy Model between Alloy Adding Amount and Material Characteristics

JI CHUNRONG, LI YAN, BAI WANMIN, WANG DAMING

1998, 16(2):  209-214. 

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Based upon RM Tong's thought of regarding fuzzy model as the set of fuzzy conditional proposition by converting the accurate value into a fuzzy one, the structure of a fuzzy system formed by alloy element adding amount and material characteristic norm is determined, and then the fuzzy model of the system is built. This new general method for studying the influence of alloy adding upon the material characteristics is presented in detail.

A Stabilizing Method of Three Classes of Nonlinear Systems with Limited Uncertain Disturbances

SHI XIAOPING, WANG ZICAI, MA KEMAO

1998, 16(2):  215-221. 

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Using the exact linearization theory for nonlinear systems, we transform three classes of affine nonlinear systems with limited uncertain disturbances into linear ones with uncertain parameters, and then solve the stabilization problem of the original systems with the aid of pole assignment method.

Study on the Attitude Algorithm of Strapdown System

CHENG JIABIN, ZHANG YANHUA

1998, 16(2):  222-228. 

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The quaternion attitude algorithms are studied in this paper. The scale error, skew error and drift error for algorithms of different kind are clearly described by using U-S fraction of attitude matrix. Coning error and algorithm optimization are also discussed in this paper.

PI Type Constrained Receding-Horizon Predictive Control

CHEN ZENGQIANG, YUAN ZHUZHI

1998, 16(2):  229-233. 

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Based on the constrain of the receding-horizon predictive output and the optimzation of the multiple-step predictive control cost function,the PI type constrained receding-horizon predictive controller is designed. The simulation results are demonstra ted, showing the excellent property of this method.

Fuzzy-Randomness in the Analysis of Structural Reliability

JIANG CHENGYI, DENG CHAORONG

1998, 16(2):  234-242. 

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The theory and method for structural reliability design with the influence of uncertain factors of both randomness and fuzzyness are discussed in this paper.

Synthesis, Structure and Properties of Slicon Containing Quinone-Amine Polymers

GAO NAN, LU XUEFANG, LU CHENG

1998, 16(2):  243-248. 

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Two new kinds of soluble silicon containing quinone amine polymers (PQA) were synthesized by T,k-diaminoalkoxy polymethylsiloxane and T,k-diaminoalkyl polymethylsiloxane reacted with p-benzoquinone. PQA can be cured by mixing chloro sulphonated polyethylene and epoxy resin, and the products are a kind of water-proof and rust-proof coating film with low moisture absorption and good saltwater resistance.

The Multi-Particle Interaction of Electrorheological Fluids

GAO XIANGYANG, ZHAO XIAOPENG, ZHENG CHANGQING

1998, 16(2):  249-252. 

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We presented a modified conductivity model for the attractive force of a perfect particle chain in a nonpolar liquid. With the concept of equivalent plate thickness, we calculated the periodic electric field in a chain and the periodic charger in the plate surfaces. We obtained the total attractive force of particles with a linear superposition method where the multi-particle effect in a perfect chain was concerned. We also compared the predicted quasistatic yield stress with the experiment data of two materials, Alooh/Silicone oil and Zeolite/Silicone oil, and found they are in a well agreement.