Table of Content

30 September 2000, Volume 18 Issue 3

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Articles

The Stationary and Dynamic United Decoupling and Compensating Method in a Multi-axis Force Sensor

XU Ke-jun, LI Cheng

2000, 18(3):  189-193. 

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This paper proposes the stationary and dynamic united decoupling and compensating method, a mothod to tackle the three main problems involved in a multi-axis force sensor. The stationary decouple, dynamic decouple and dynamic compensation are combined into an integral whole. Three key technique problems of multi-axis force sensor are solved simultaneously, and the sensor's follow-up processing is simplified. The results of simulation have proven the correctness and effectiveness of this method.

The Effect of the Inclusions in Weld Metals for Flux Cored Wires on the Forming of Acicular Ferrite

YU Sheng-fu, SHI Zhong-kun, LI Zhi-yuan, WANG Jie

2000, 18(3):  194-197. 

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The sizes of non-metallic inclusions in weld metals for flux cored wires and the rule of their distribution are systematically studied. The chemical composition and the figures of nonmetallic inclusions in weld metals are analyzed with transmission electron microscopy and X-ray microanalysis. The results show that the non-metallic inclusions beneficial to nucleation and growth of acicular ferrite in weld metals are oxidation products of Ti, Mn, Si, Al and the sulphides of Mn and Cu. The percentage of Ni,Mn and Mo in the weld metals and welding energy input have little effect on the chemical composition,sizes and figures of non-metallic inclusions in the weld metals. As nucleation sites, the non-metallic inclusions can reduce the nucleation energy remarkably. Besides they have different thermal expansion coefficients from that of the substrate metals, which will introduce a high stress-stain field around the inclusions during the cooling process. These two factors are the main driving forces to the nucleation and growth of acicular ferrite.

A New Structure Fault Detection Method Based on Wavelet Singularity

HU Shou-song, ZHOU Chuan, HU Wei-li

2000, 18(3):  198-201. 

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A new type of fault diagnosis strategy based on wavelet singularity detection is presented in this paper. In this method, the signal is firstly processed by discrete binary wavelet transform. It is then denoised through modulus maxima algorithm, and fault detection and positioning is completed by the modulus maxima point distribution in wavelet transformation. This method can evidently eliminate the affection of noise on residual signal and improve the robustness of fault detection. Finally, this method is applied to the fighter's structure fault detection. Simulation results show that the presented method is effective.

A New Crystal LiNbO₃ Detector Calculating Method

WANG Yu-sen, CHENG Dong-fang, ZHAO Leng-zhu

2000, 18(3):  202-207. 

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For a new crystal LiNbO₃ detector, a new theoretic calculating method is presented for the first time. In this method, the phase retardation is directly related to the radiation field without the standardization of quadratic equation under the arbitrary field. Taking into account of the distribution of the field and group velocity mismatch we also give the optimized size of the new detector.

The Application of Wavelet in the Approximation of Non-linear Time Series

XIE Mei-ping, ZHAO Xi-ren, ZHUANG Xiu-long

2000, 18(3):  208-210. 

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The approximation properties of wavelet networks which is applied to non-linear time series is studied in this paper. Moreover, compared with projection pursuit learning networks and improved back propagation learning, wavelet networks have good fitness and forecasting properties.

Adaptive Fuzzy Modeling and Its Use in Ship Dynamic Positioning

RUI Shi-min, ZHU Ji-mao

2000, 18(3):  211-213. 

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Ship dynamics is always hard to model, and the statistics of stochastic environment forces (wind, waves, current flow, etc.) are changing all the time in different sea states. Therefore, the authors introduce an adaptive fuzzy logic system in ship dynamic positioning. The dynamic model is obtained by learning the ship's drift dynamic behavior through using fuzzy logic. Furthermore, the desired control force determined by minimizing the error between predicted and desired ship position at the next step. Simulations at different sea states have shown that the scheme is effective.

Multi-user Detector Using Timevarying Scaling-parameter Transiently Chaotic Neural Network

ZHONG Wen, CHENG Shi-xin

2000, 18(3):  214-217. 

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The existing neural network multi-user detectors are often trapped in the local minima, resulting in the performance degradation. In this paper, a timevarying scaling-parameter transiently chaotic neural network (TSTCNN) is proposed. The TSTCNN network has powerful capability to escape from getting into the local minima. The TSTCNN network is applied to the optimum detection problem in DS/CDMA systems. Numerical results show that the TSTCNN-based detector can perform better than the existing neural network detectors. The proposed detector can approximate to the optimum detector closely.

Performance of the Rake Receiver of CDMA2000 Reverse Link

XU Chang-long, YOU Xiao-hu

2000, 18(3):  218-222. 

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Multi-carrier and direct spread are used in CDMA2000 for supporting wideband data service. To improve performance of the receiver, the pilot channel is added to the reverse channels. But the signals of I and Q are different now. In this paper, we introduce the structure of the reverse channels and discuss the principle of the Rake receiver. Basing on this, we set up the model of the Rake receiver and carry out computer simulations. Finally, we analyze the result and draw an ideal conclusion.

The Effect of Amplitude and Phase Errors on the Performance of Adaptive Array Antenna

NI Jin-lin, SU Wei-min, CHU Xiao-bin

2000, 18(3):  223-226. 

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This paper analyzes the output SINR of adaptive array antenna in the presence of amplitude and phase errors. The analysis shows that the amplitude and phase errors has little effect on the output SINR of adaptive array antenna. The results were validated by computer simulation.

Theory and Experiment of Corner Fed Dual-polarized Active Patch Antenna Array with Low-noise Amplifiers

YANG Xue-xia, ZHONG Shun-shi, GAO Shi-chang

2000, 18(3):  227-231. 

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New expressions for input and mutual impedance of corner-fed dual-polarized patch antenna double-and corner-fed by microstip line are derived on the basis of Green function method. Array patterns of the co-and cross-polarization are calculated by using the cavity theory. A 4×4 dual-polarized array integrated with low-noise amplifiers is designed and tested. An extra gain of 12dB comparable with the respective passive array is achieved at the central frequency. The radiation patterns have nearly no changes with the integrated amplifier, while the cross-polarization is lower than -36dB in the main lobe region. The bandwidth and isolation are largely increased when compared with those of the same array without the amplifiers.

Insertion Loss Synthesis for any Transmission Functions of Networks

LI Feng, XIANG Chang-shun, LI Xiao-yan

2000, 18(3):  232-236. 

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In this paper the insertion loss synthesis for voltage transmission functions K_v(s) is extended to synthesis for current transmission functions K_I(s), transfer admittance functions G_m(s) and transfer inpedance functions Z_m(s). Another important result is:If there are K_I(s)=G_m(s)=Z_m(s)=K_v(s), and R₁=R₂=1Ω, then extant filter design digital forms for K_v(s) can be used to design filters for K_I(s), G_m(s) and Z_m(s).

Domain Decomposition Method: A Rigorous Algorithm for the Full-wave Analysis of Three-dimensional Microwave Structures

YIN Lei, HONG Wei

2000, 18(3):  237-241. 

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In this paper, a full-wave domain decomposition method is presented for the analysis of three-dimensional microwave structures. Compared with other methods, it can greatly reduce the computing complexity and resource requirements for splitting the problem into finite independently sub-problems. The paper discusses in detail the implementation of the method in combination with FDFD method. The scattering parameters of a multilayered structure embeded in rectangular waveguide and a multilayered aperture-coupled antenna are analyzed by using the DDM. The complete agreement between our method and original FDFD method demonstrates the validity and flexibility of the method.

Application Study of Digital Servo Technology in Brushless DC Motor Control

CHEN Wei-yuan, ZHOU Zheng-wei, WANG Hao-cai

2000, 18(3):  242-245. 

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Digital servo control technology has become more and more important in motor control because of its high precision, reliability and flexibility. This paper offers a three dimension solid model of the brushless DC motor with CAD and CAA which can calculate the physical parameters of the motor quickly and accurately. The model of digital servo control system for brushless DC motors is provided; the related speed and phase control loop are designed; and the system is programmed and realized in the single-chip microprocessor μPD78148.

Research on Forces Modeling of Ball-end Milling Cutter Based on Power Method

LI Shui-jin, JIN Ren-cheng, ZHOU Yun-fei, ZHOU Ji, TANG Xiao-qi, JIA Yu

2000, 18(3):  246-250. 

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According to the principle of power keeping constant in the process of cutting, this paper systematically studies the forces performance of cutting edge of ball-end milling cutter and develops a new forces model based on power by strict mathematical means so as to overcome the fault which results from the fact that forces modeling depends mainly on the orthogonal cutting experiments. The experiment results prove that the model presented in this paper can precisely predict the 3D forces of ball-end milling cutter in cutting, and has important engineering value.

Analysis of Discrete Scheme for Flux Density in Hydrodynamic Model

WU Jin, LIU Qi-gui, YANG Lian-feng, WEI Tong-li, CHEN Chun-ming

2000, 18(3):  251-254. 

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The discretization of current density and energy flux density equations are very important in the numerical analysis of semiconductor devices. In this paper, we present a new discretization method of the above two physical quantities, which has been used in device modeling based on hydrodynamic model and finite difference methods.

Influence of Boron Ion Implantation on the Electret Properties and Mechanic Properties of Si₃N₄ Film Based on Silicon Substrate

ZHANG Xiao-qing, XIA Zhong-fu, PAN Yong-gang, ZHANG Ye-wen, LI Bao-qing, LIN Zi-xin

2000, 18(3):  255-258. 

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Amorphous silicon nitride (Si₃N₄) film has outstanding electret properties and it is compatible with the micromachining technology, so it can be used in miniature microphone. But big tensile stress of Si₃N₄ film limits its application. In this paper, the improvement of mechanical property of Si₃N₄ film by boron ion implantation and its influence on the electret properties of the film is discussed. The results show that the boron ion plantation reduces the tensile stress of film effectively,but it also decreases the electret properties of the film. The capability of Si₃N₄ electret film against environmental conditions can be increased by chemistrical surface modification. Therefore, Si₃N₄ film may be used as a vibrating film. After the stability of charge storage is improved,it may be used as electret material for miniature microphones.

A Base Transit Time Model for Ultra-thin-base SiGe HBT

LI Yao, LIAO Xiao-ping, WU Xiao-jie, WEI Tong-li, XU Ju-yan

2000, 18(3):  259-262. 

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The influences of non-equilibrium effect on the carrier temperature and diffusion coefficient in the ultra-thin-base SiGe HBT are analyzed in this paper. This leads to the forming of a base transit time model for ultra-thin-base SiGe HBT.

Study on Effective Thermal Conductivity of Real Porous Media by Using Fractal Theory

CHEN Yong-ping, SHI Ming-heng

2000, 18(3):  263-266. 

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On the basis of fractal theory and by means of the section view of porous media,the geometric structure of real soil was described with its section view and section particle area fractal dimension d of porous media was counted. The volumetric solid content and the relation between volumetric solid content and porous media particle arrangements as well as measure scale were obtained. A heat conduction model was thus established and the effective thermal conductivity of real soil based on the volumetric solid content was calculated.

Optimal Map Recognition Method Applied to Molecular Sieving of Antifungal Activities of 1-(1H-1, 2, 4-Triazole-1-Y1)-2-(2, 4-Difluorophenyl)-3-Substituted-2-Propanols and Their Reduced Products

LU Wen-cong, SU Xiao, FENG Jian-xing, CHEN Nian-yi

2000, 18(3):  267-270. 

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A new pattern recognition method called optimal map recognition (OMR) method is proposed to select the optimal projection map among various pattern recognition maps. The inequalities describing the boundary conditions of optimal samples in original space can be established by OMR method. The OMR method has been successfully applied to computer-aided molecular sieving of antifungal activities of 1 -(1H-1, 2, 4-triazole-1-yl)-2 -(2, 4-difluorophenyl)-3 substituted-2-propanols and their reduced products. The new compounds with probably higher anti-fungicidal activities are determined by the inequalities describing the boundary conditions of samples with high antifungal activities in original space.

Complete Sequence Behavior Invariance of Synchronous Composition Nets

JIANG Chang-jun

2000, 18(3):  271-275. 

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The complete behavior invariance is defined. The concepts such as root isomorphism, etc. are introduced. A simple decision for the complete behavior invariance is given. Moreover, the roles of the complete behavior in preserving properties such as liveness and fairness and so on are studied. The conditions sufficient and necessary for preserving these properties under the complete behavior invariant are obtained.

Finding the Optimal Cutting Method with Genetic Algorithm

MENG Fan-zhen, ZHANG Qing-cui

2000, 18(3):  276-279. 

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In this paper, a genetic algorithm is used to find the optimal cutting raw material method and the algorithm of this problem is also given by means of genetic algorithm.

Reliable H_∞ State Feedback Control of Uncertain Nonlinear Systems

FU Yu-sun, TIAN Zuo-hua, SHI Song-Jiao

2000, 18(3):  280-282. 

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This paper is concerned with the reliable state feedback controller design problem for a class of uncertain nonlinear systems. By using dissipative theory, a procedure of designing reliable nonlinear controller is presented in terms of the solutions of the Hamilton-Jacobi inequality. The resulting closed-loop system is reliable in the sense that the performance (i. e., internal stability and H_∞ attenuation) of the closed-loop system is guaranteed not only when all actuators are operational, but also when some actuator outages occur.