Table of Content

31 December 1999, Volume 17 Issue 4

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Articles

The Charge Decay Dynamic Characteristic of Teflon-AF/Nonlinear Optical Polymer Electret Double Layer System

CHEN GANGJIN, XIA ZHONGFU, ZHANG YEWEN, ZHANG HONGYAN

1999, 17(4):  379-383. 

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In this paper,the charge decay dynamic characteristic of the Teflon-AF/nonlinear optical polymer electret double layer system,which is poled with the method of constant voltage corona charging,is studied by means of measuring the open-circuit thermally stimulated discharge (TSD),electro-optical coefficient and surface potential decay. The results indicate that the reason of stability improvement of oriented dipoles for the double layer film system is that Teflon-AF electret layer have high storage stability of space charge,and the dipole alignment is kept by the field form ed by the space charge layer situated in the Teflon-AF layer and the interface between the Teflon-AF layer and the N LO polymer layer.

A Study of Charge Storage Stability Mechanism for Porous Polytetrafluoroethylene (PTFE) Film Electret

CUI LILI, JIANG JIAN, XIA ZHONGFU, SONG JUPING, CHEN GANGJIN, ZHANG YEWEN

1999, 17(4):  384-388. 

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The space charge storage stability of porous polytetrafluoroethylene (PT FE) films was studied and comparied with the solid PTFE film by means of the isothermal surface potential decay and the open circuit thermally stimulate discharge (TSD),etc. The shift rule of mean charge depth for the porous electret film was investigated and then the charge transportation characteristic of the film was studied by TSD experiment and thermal pulse technique.

Influences of the Surface Plasm on Polariton on Negative Resistance Phenomenon at Electrical Contact Interface

WU ZHONGHAN, SUN JIAN, WANG MAOXIANG, CHEN WEI, SUN CHENGXIU, ZHANG JIGAO

1999, 17(4):  389-394. 

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At electrical contact interface of metal-isolator-metal (MIM) or metal-isolator-isolator-metal (MⅡM),SPP (surface plasmon polariton) will appear.SPP has two existing forms:producing radiation and not producing it.This paper focuses on the analysis of negative resistance phenomenon of MIM's SPP and related problems.

The Study of the Microstructure and Mechnical Properties of Composites Produced by Reaction Between MoSi₂ and B₄C

LI JIANLIN, JIANG DONGLIANG, TAN SHOUHONG

1999, 17(4):  395-399. 

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In this article,the microstructure and mechnical properties of composites produced by the reaction between MoSi₂ and B₄C during the hot pressing process were studied.The results indicated that the composites are mainly consisted of MoSi₂,Mo₂B₅ and small amount of SiC and Si.The mechnical proper ties of composites which compared with monolith Mo Si₂ material were greatly improved.Bending strength and fracture toughness reached the highest value of 380MPa and 3.9MPa· m^1/2,respectively,at ambient temperature when B₄C addition is of 10%.On the other hand,hardness of the composites increased with the increasement of B₄C addition.

The Influence of Ion Substitution of Ba(Zn_1-x Co_x)₂Fe₁₆O₂₇ Hexaferrite on the μ_i-T Curve

DENG LONGJIANG, XIE JIANLIANG, CHEN XUANZHEN

1999, 17(4):  400-404. 

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Two peaks (I、Ⅱ) of μ_i-T curve have been found in the planar anisotropic Ba(Zn_1-x Co_x)₂Fe₁₆O₂₇ hexaferrites prepared by ceramic process in this paper, and the second peak Ⅱ moves to higher temperature as Co²⁺ substitution increase, but as Cu²⁺ substitution increase it moves to lower temperature. The experiment results correspond with the influence of temperature on the magnetic crystalline anisotropic constant K_u1、K_u2、K_u3, and are a great help to improving the temperature stability of the materials.

Investigation of Polymer Surface Dynamics Modified by Plasma by Using Dynamics Contact Angle Method

SHI LAISHUN

1999, 17(4):  405-410. 

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The dynamics contact angle of some polymer materials is studied. For untreated polymers, it is found that advanced contact angle is greater than recede contact angle. The hysteresis between the advanced contact angle and recede contact angle is attributed to the heterogeneous of the chemical composition on the polymer surface. For the polymer materials treated by CF₄/CH₄ plasm a, it is found that the advanced contact angle increases greatly com pared with the recede contact angle. The hysteresis increases because of the increasing of chemical composition heterogeneous on the polymer surface. The surface dynamics decay rate constant changes with the plasm a treatment condition of CF₄(%) during the immersion of water for the polymer film s is treated by CF₄/CH₄ plasm a. Thew hole range of CF₄(%) can be divided into three regions, which are distinguished by their different plasm a mechanistic aspects, and different properties of the plasm a polymerized film s. The rate constants of polymer film pretreated by CH₄ plasm a are lower than that of unpretreated polymer film s. It proves that an ultra thin barrier layer provided by CH₄ plasm a is effective to prevent the movement of surface dynamics.

Preparation and Magnetic Properties of Nanocrystalline Exchange-coupling Rare-earth Permanent Magnet

YANG SHIQING, ZHANG WANLI, GONG JIE, PENG BIN, WANG HAOCAI

1999, 17(4):  411-415. 

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The amorphous Nd_8.16Dy₁Fe_85.26Nb₁B_4.58 ribbons have been fabricated by means of melt-spun over quenching.Microstructure investigation by XRD and TEM of the amorphous and crystal ribbons is reported.the magnetic properties and their dependence of temperature were determined using vibrating sample magnetometer (V SM). The influence of annealing temperature,time and addition of Dy,Nb on the magnetic properties of nanostracture rare-ear th permanent magnet has been also investigated. The nanostructure exchange-coupling permanent magnet with higher Curie temperatue and higher coercivity and positive remanence temperature coefficient have been obtained.

Calculation of Invariant Probability Distribution for Chaotic Maps Using Eigenvector Method

DAI XUCHU, ZHANG JINGANG, XU PEIXIA

1999, 17(4):  416-420. 

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A new method of direct calculation of invariant probability distribution for chaotic maps is derived from Frobenious-Perron equation.The method circumvents disadvantage of histogram method,and is particularly useful for some realistic experimental system whose transfer probability matrix is easy to be determined.

A Study of the Scattering Characteristic of the Non-specular Waves on the Dielectric-coated Curved Surfaces

LIN CHISEN, TANG JUNWU, HAO SHUNING

1999, 17(4):  421-426. 

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In this paper, a new concept of the surface-creeping waves is proposed.With the novel approach, the scattering characteristic of non-specular waves is investigated and some valuable results are obtained and illustrated.

Principal Component Feature for Speech Recognition

HE ZHENYA, GU MINGLIANG, WANG TAIJUN, SHI XIAOXING

1999, 17(4):  427-432. 

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Using curve fitting and principal component analysis method,this paper presents a novel ANN-based speech recognition feature.The feature reflects the variation of vocal tract with time.The extraction method simulates the processing of speech information in human auditory system.Compared with other ANN-based recognition features,this new feature not only increase the recognition accuracy but also has following properties:less complex algorithm,less storage memory and easy realization with hard ware.

Study of a Novel Sensor System for Noninvasive Measurement of Blood Oxygen Saturation

CHANG CHANGYUAN, WEI TONGLI

1999, 17(4):  433-438. 

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The principle and method of noninvasive measurement of blood oxygen saturation (SaO₂) is presented in this paper which analyzes the characteristics of light transmitted through the fingertip.Based on this method,a novel sensor system for noninvasive measurement of blood oxygen saturation has been designed and fabricated.Clinical results show this system have good consistency with blood-gas analyzer and the coefficient of correlation comes to 0.984.

Research of the Preparation of Artificial Muscle on pH and Its Mechanical Performance

GUO XIZHANG, GONG ZHENBANG, LIU DONGSHENG, HUA JIADONG, WANG QINQUE

1999, 17(4):  439-444. 

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Preparation and mechanical behavior of artificial muscle based on pH sensitive polymer gels was discussed in this paper.The fine gel fiber which could be called to be an artificial muscle were prepared from commercially available poly (PAN) fibers by the annealing and saponification and a massive carboxyl group was contained.Finally we introduced a novel parallel mechanism that driven by artificial muscle,which has already constructed and experimented in our laboratory

The Open-plus-closed-loop Control for Chaotic Oscillations

CHEN LIQUN, LIU YANZHU

1999, 17(4):  445-449. 

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The open-plus-closed-loop control of chaos in nonlinear oscillating systems is investigated in this paper.The open-plus-closed-loop control law for sing le-degree-of-freedom chaotic oscillations is established.The forced Duffing oscillator is treated as a numerical example to demonstrate the effectiveness and robustness of the control law. The control law is also extended to multi-degree-of-freedom oscillating systems.

Design and Implementation of a Syntax-driven Z Specification Checker

LIGANG, MIAO HUAIKOU, TONG FU

1999, 17(4):  450-456. 

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Z specification language is an active domain in the field of formal methods. As the front-end of any Z supporting system,Z specification checker can support other subsystems,such as refining subsystem,and specification-based software testing subsystem.By the integration of top-down parsing and bottom-up parsing,a syntax-driven Z specification checker has been implemented.This paper gives a description of the principle and implementation of this tool.

An Estimation of Nonlinear Transfer Function for Wrist Force Sensor in Frequency Domain

XU KEJUN, LI CHENG

1999, 17(4):  457-462. 

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This paper investigates the dynamic nonlinear characteristic of wrist force sensor in the frequency domain.The reasons for dynamic nonlinearity are analyzed,and the determining methods of time and frequency domain are studied.The sensor's transfer functions of linear and nonlinear are estimated.When input is non-Gaussian signal, the solution of quadratic nonlinear transfer function is presented.The determining method of main nonlinear frequency range is discussed.The constructed system is simulated,and the experimental data are analyzed.The results indicate that the nonlinear analyzing method can describe the sensor's dynamic characteristic more accurately.

Pulse Electromagnetic Light Valve Based on Adaptive Fuzzy Control

HU HANPING, WU XIAOGANG, MU CHENPENG, LI DEHUA, WANG ZUXI, ZHOU YAN

1999, 17(4):  463-468. 

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This paper introduces an adaptive high-speed pulse electromagnetic light valve.Because of some uncertainty of electromagnetic light valves,in order to raise the frequency of the valve in certain basic structure by adjusting the parameters of drive current,we observed the status of the valve in various controllable parameters through experiments.Then,these data are used to design adaptive fuzzy control system by means of genetic algorithms.The advantages of the valve are no influence on the character of the light path,simple structure,long life,high frequency and relatively large switch calibre,etc.The valve is applied successfully in 3D laser scanning equipment.

The Application of Data Fusion in Automated Measuring System of Moisture Content for Grain Storage

TENG ZHAOSHENG, YU WENXIAN

1999, 17(4):  469-472. 

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Data fusion can help improve the accuracy and reliability of automated measuring system of moisture content for grain storage.This paper discusses the problem of multisensor data fusion based on parameter estimation of automated measuring system of moisture content.The fusion algorithm of measuring moisture content is given in theory. The auto mated measuring systems based on data fusion of moisture content are widely using in grain storage.

A Backfire Antenna Fed by a Bifilar Backfire Mode Helix

HAO JIN, MA FUCHANG, LI HONGYING, LI RUILIAN

1999, 17(4):  473-475. 

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A backfire antenna of good characteristics is described in this paper.It has a new feed-bifilar backfire helix.Its four situations of pitch angles T=10°,12°,14ånd 16° are measured.By comparison,the best pitch angle is 14°.The antenna has a maximum gain of 19.7dB.The new antenna has the advantages of simple structure,easy feeding and a wide frequency rang e,and circular polarized wave.The characteristics are much better than a bifilar backfire helical antenna,a short backfire antenna and a backfire antenna fed by a mono filar backfire helix.

A New Reduced Order State Stabilization Method for a Class of Nonlinear Systems

WANG ZICAI, SHI XIAOPING, WANG XU

1999, 17(4):  476-478. 

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This paper provides a new reduced order state stabilization method,which is suitable for a class of nonlinear systems that open appears in the field of vehicle control engineering.As an example,an attitude stable control law of some interceptor is designed in the paper.

Double Loop Hierarchical Algorithm for Multi objective Optimization Problems of Steady-state Large Scale Systems

QIAN FUCAI, LIU DING, WAN BAIWU

1999, 17(4):  479-484. 

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This paper proposes a double-loop hierarchical algorithm for multiple objectives optimization.First,the algorithm assembles the multiple objectives into one objective by the preference of decision-maker,and then em beds the nonseparable one objective optimization problem into separable multiobjective optimization problem.Finally,the optimal solution of the nonseparable problem can be obtained from the set of solutions of the separable multiobjective optimization problem,this optimal solution is provided as one non-inferior solution of the original problem.

Effect of Me on Valence Electron Structure of Fe-Me-CAlloyed Austenite

LÜ YUPENG, ZHU RUIFU, LEI TINGQUAN, LI SHITONG, LI MUSEN

1999, 17(4):  485-488. 

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This paper deals with the analysis of effect of Me (alloying element) on valence electron structure of Fe-Me-C alloyed austenite taking Fe-Mn-C austenite for example.The results show that Me content can affect the occurence probability of all kinds of atomic configurations,i.e.the relative amount of cells.By modifying the equation calculating the atom fraction of carbon into A_c=100C/12\[((100-C-m)/56) + C/12 + m/M],the effect of Me on crystal parameter can be characterized.Me influences the valence electron structure of alloying solid solution principally th rough its effects on crystal parameter,iso-bond number and right of cells.

A Method for Air-towing Lines Used in Constructing High Voltage Transmission

LIU ZHIJIAN, WANG QINHUI, YAO ZHUANLE, XIE LIKE

1999, 17(4):  489-492. 

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A method for air-towing lines used in coustructing high voltage transmission lines is introduced.It is applied to 82mm artillery launching and flight vehicles for towing lines,and solved the technical diffrculties such as the configuration and weight of flight vehicles and the pulling apart of lines.The lines can be tow ed 550m away.

The Preparation and ER Effect of Electrorheological Fluid ofProtein Silver

ZHANG CHAOPING, HU LIN, HU ZONGCHAO, ZHANG CHAO, HE FENG, XIAO HONGPING, DENG WEI

1999, 17(4):  493-497. 

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The synthesis of protein-silver ultrafine particles by inverted microemulsion method and the preparation of ER fluid of these particles dispersing in insulating oil are reported.Several parameters of the ER fluid are studied including the structure,stability,static yield stress (τ_s) and the leakage cur rent density (J).Factors which affect the above parameters are discussed.The ER fluid of protein-silver shows high yield stress and low leakage current even in weak electric field (E),and J^∝aE^b.