Table of Content

30 June 1994, Volume 12 Issue 2

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Articles

EXPERIMENTAL STUDIES ON THE THERMAL EXPANSION BEHAVIOUR OF SINGLE CRYSTAL TELLURIUM DIOXIDE LU CHANGWEI XI TONGGENG

LU CHANGWEI, XI TONGGENG, CHEN YUNXIAN, YANG XUEHUA, XU YIBIN, PU ZHIFEN

1994, 12(2):  95-100. 

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In this paper,the thermal expansion behaviour of the TeO₂ single crystal is studied experimentally by the push-rod dilatometery Tg-DTA and X-Ray diffraction methods.It is the first time to measure the thermal expension coefficient of the TeO₂ single crystal along a and c axes in the temperature region of 370~500℃ by the push-rod dilatometer method.Furthermore,the anisotropy of the thermal expansion of the TeO₂ single crystal is studied according to the structure and the characteristic of cleavage as well as the comparison of the chemical bonding strength of a and c axes.

THE INFLUENCE OF CHEMICAL SURFACE MODIFICATION ON CHARGE STORAGE STABILITY IN THE THERMALLY CROWN SiO₂ FILM ELECTRET

LIN HUAMAO, XIA ZHONGFU, DING HAI, SHEN SHAOQUN

1994, 12(2):  101-108. 

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In this paper,the influence of chemical surfaee modification on charge Storage stability in the thermally grown SiO₂ film electret is studied.A hydrophobic protective layer is formed on the surface of the SiO₂ film electret by an appropri-ate chemical surface modification (using HMDS or DCDMS).Generally,this hydrophobic layer prevents water absorption on the surface of SiO₂ and makes the SiO₂ electret an excellent electret.During the permanent charge captue and storage in the SiO₂ film electret,an electrochemical reaetion takes place and water is produced.The hydrophobic layer formed after chemical surface modification sometimes obstructs the excess water from diffusing out of the electret.In this condition,an unusual phenomenon occurs:the charges stored in the SiO₂ electret modified by HMDS or DCDMS decay faster than surface.

ANALYSIS OF INTERNAL DECAY OF CHARGES IN PP ELECTRETS OUYANG

OUYANG YI, XIE XISHUN

1994, 12(2):  109-112. 

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In this paper,the charge-decay of polyproplene (PP) film electrets is analysed.It is shown that the hopping of intrinsic carriers impelled by internal field is the main reason for potential-decay.The average hopping stop-distance calculated from the test data is about the order of 10^-8 m. This result has been demonstrated by the X-ray diffraction of the film recently.

CALCULATION OF TRANSIENT RESPONSE OF A TWO-DIMENSIONAL CONDUCTING CAVITY USING MARCHING-ON-IN-FREQUENCY METHOD

PENG ZHONGQIU

1994, 12(2):  113-119. 

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The integral equation is handled using the method of momentes in the complex-frequency domain,the space discretization is fixed for all frequencies and the resulting matrix equation is solved by the conjugate gradient method. The condition of the system matrix is improved in the complex-frequency domain. Good initial estimates are obtained using an extrapolation scheme based on error minimization,thereby the conjugate gradient method converges very fast. The transient response is obtained by carrying out the inverse Laplace transfo rmation by an FFT algorithm. The results of a rectangular cylindrical cavity verify the effectiveness of the new method.

STUDY OF LEUKOCYTE FEATURES IN PERIPHERAL BLOOD FOR AUTOMATIC CLASSIFICATION YANG XIAOMIN

YANG XIAOMIN, LUO LIMIN, WEI YU

1994, 12(2):  120-126. 

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For each cell,a total of 35 features in three kinds are extraeted from the automatic classification system of peripheral blood leukocytes.They are:7 morpho-logic features,12 optical densiey features and 16 texture features.The testing for 1200 leukocytes indicates that using these three kinds of features is better thanjust using the first 2 kinds,and the accuracy rate is approximately 90%. The result is discussed.

AN APPLICATION OF BIPATITE CONNECTIONIST MODEL IN VLSI HIERARCHICAL GLOBAL ROUTING

SHEN TAO, GAN JUNERN, YAO LINSHENG

1994, 12(2):  127-132. 

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The application of the Bipatite Connectionist Model in global routing on 2×2 cells was studied in this paper. The structure of the network was given along with its simulation algorithm.

CIRCUIT STATISTICAL OPTIMIZATION TECHNIQUE UNDER SEQUENTIAL CONVEXITY OF FUNCTIONS

HAO YUE

1994, 12(2):  133-139. 

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Based on the unitized model of design centering for maximum manufacturing yield,optimal toleraneing design, optimal tuning design and design of minimized manufacturing costs of integration,an efficient method of solving DCTT is given under the conditions of sequential convexity of functions in this paper. The method combines the deterministic optimization technique with the orthogonal optimal experiment method to change the 2ⁿ vertices of the tolerance region into (n+1) constraint conditions,and uses nondifferentiable optimization to solve the DCTT problem directly. Therefore,the method can solve large scale IC statistical optimization problems.

MOS PHOTO-ELECTRONIC SWITCH IC

CHEN DONGFANG, ZHAO GUOZHU, CAI RENKANG, GU MING, WANG LIANG

1994, 12(2):  140-144. 

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The principle of photo detection by accumulation and the design of MOS photo-electronic switch IC are introdueed.The advantages of the IC are:low cost,low power consumption and multiple functions. Some applications of the IC transducer are presented.

A PIEZOELECTRIC STEP MOTOR WITH SUBMICROMETER STEP SIZE

WANG ZHAOQIU, ZHANG JIE, ZHANG SHUYI

1994, 12(2):  145-149. 

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The operation condition and scanning velocity of a piezoelectric step motor have been studied. It is found that the up and down slopes of the pulsed voltage applied to the piezoelectric step motor not only limit the maximum velocity of the stepper, but also determine the operation condition. In our system,the mechanical and electronie components of the stepper are compact and simple,and the electromagnetic noise has been reduced by taking a shield shape.

FADING RECURSIVE FILTERING AIDED SPECTROSCOPY An Optimal Adaptive Algorithm

LI ZHILIANG, YU BANMEI, QIAN FENG, SHI LEMING, PAN ZHONGXIAO, NIE SHENGZHE

1994, 12(2):  150-158. 

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The fading Kalman recursive optimal filtering is studied for spectroscopic resolution,Based on the nature of Kalman filter that the residual sequenees are not correlated when the optimal gain is obtained, a new fading filtering-optimal adaptive algorithm is proposed and utilized. Through the on-line and adaptive adjustment of the fading or forgetting factor,the convergency and optimality of Kalman filtering are improved using measured outputs or estimated results, even when there exist model errors and/or when the system is affected by unmeasurable external disturbances.The algorithm developed is applied to overlapped peak resolution with good results.

STUDY AND DESIGN OF FLEXURE HINGE PRECISE POSITIONING SYSTEM HAVING RELATIVE WIDE RANGE

ZHU FENG, ZHANG HONGHAI, CHEN RIYAO, HUANG QIKUI

1994, 12(2):  159-164. 

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In this paper,the design of the flexure hinge positioning system having a relative wide range is studied.The paper gives the calculation and formulas for designing the flexure hinge. The flexure hinge mechanism amplified by a two step lever is achieved. It is shown by experimental results that the resolution of the precise positioning system is higher than 0.5μm and that the adjusting range is 180μm,In addition,the paper also discusses the driving property of a piezo-electric actuator used in the flexure hinge machanism.

THE PRINCIPLE OF HARDWARE OPERATED AT THE SAME FREQUENCY IN DIFFERENT PERIODS FOR REAL一TIME FUZZY REASONING

PANG FUSHENG

1994, 12(2):  165-170. 

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The principle of the hardware for real-time fuzzy reasoning is introduced in this paper. The reasoning unit,though it consists of a few fuzzy logical devices,can draw a simple inference at high speed.The membership functions of the engine are regarded as the waves scanned with the same frequency.Three operations needed by the inference are aceomplished in two periods.

METHODS OF IMPROVING THE EVENNESS OF MAGNETIC FIELD

XU SHUJUN, XU YOUPENG, JIN BIANJUN, ZHANG YIBING, SHI TAIHUA, LU YUQING

1994, 12(2):  171-178. 

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A NMR-CT magnet model with scale 1/6 is now being assembled at our laboratory.3.5kG central field is generated by permanent magnet and evenness of field within the cylinder of 0.02083m radius is 1426×10^-6. In order to improve the field evenness,we changed the shape of magnetic pole,increased the iron content at the edge of pole face. Consequently,the evenness of field in the same range increases by a factor of 16.5,i.e. 86.4×10^-6 is obtained.Comparing with other methods,it is very simple and showes a significant improvement in the evenness.

FINITE ELEMENT METHOD FOR MISCIBLE DISPLACEMENT OF MULTIPHASE FULLY COMPRESSIBLE FLOW

YANG DANPING

1994, 12(2):  179-188. 

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A standard finite element method for miscible displacement of multiphase fully compressible flow with dispersion is given and optimal error estimate in H¹-norm is derivedIn order to enhance the approximate accuracy,a modified finite element method,whose working quantity is almost the same as that of the stsndard method but whose convergent rate in L²-norm is optimal,is proposed.