Table of Content

31 December 1993, Volume 11 Issue 4

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Articles

MODIFIED DISCRETE CONVOLUTION METHOD FOR EM PROBLEM OF ELECTRICALLY-LARGE GEOMETRY

BO YAMING, ZHANG WENXUN

1993, 11(4):  283-289. 

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On the basis of the discrete convolution method (DOM), a modified discrete convolution method (MDOM) is proposed by zeroizing the Frobenius norm of the iterative matrix. The storage space and the multiplicative operations of MDOM are similar to those of DOM, but the convergence of the former is more stable than that of the latter. The MDOM is suitable for the electromagnetic scattering or radiation of an electrically-large body, especially for the scattering of the finite periodic structure.

ENERGY BAND STRUCTURE OF Bi-Sr-Ca-Cu-O SUPERCONDUCTORS

OAO YANG, LIU JIAN

1993, 11(4):  290-296. 

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The energy band structures of Bi-Sr-Ca-Cu-O superconductors were calculated by performing the tight-binding calculation method on the basis of EHT approximation. Results show that the Fermi surfaces are closed on the a^*b^* planes. The increase of electronic state densities on the Fermi level is consistent with the rise of T_c in this system. The regular changes of the net charges of Cu and O indicate that the ionio States of Cu and O in the Cu-O plane may influence the superconductivity of this system.

IMPROVEMENT OF DISTORTED BORN ITERATIVE METHOD IN 2-D ELECTROMAGNETIC INVERSE SCATTERING

PENG ZHONGQIU

1993, 11(4):  297-302. 

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A number of effective procedures for improving the distorted Born iterative method are proposed, including the accurate and efficient solution of the direct problem, second-difference regularization, weighted least-squares solution, estimation of the initial guess by using a priori information and multiple-frequency scheme. The convergence and stability of the iterative solution and the resolution, of the reconstruction are improved significantly.

ISOTHERMAL CURRENT INVESTIGATION ON TRAP CREATION IN ORGANIC DIELECTRICS

LIU FUDE, WANG YUFEN, YANG BAITUN, LIU YAONAN

1993, 11(4):  303-310. 

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Considering the difficulty in measuring electrons trap density and holes trap density, a surface potential model is suggested in this paper, with which the distributions of electrons trap energy density and holes trap energy density can be studied respectively. Such a method develops the theory of isothermal current put forward by J.G. Simmons. Based on that, a comparison experiment is performed to study the kinetic processes of trap creation in solid organic dielectrics under strong electrical strength. It is shown that trap generation is proportional to the time of field application, and increases exponentially with the field.

STUDY ON THE DEFECTS OF β-BaB₂O₄ SINGLE CRYSTAL BY POSITRON ANNIHILATION TECHNIQUE

LIN XIANQ, TANG DINGYUAN, SHI ZIKANG

1993, 11(4):  311-315. 

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The defects of β-BaB₂O₄ single crystals were studied by means of the positron annihilation lifetime spectrum method for the first time. And the fo rmation of the defects were discussed in relation to the crystal growth conditions and annealing treatments.

KINETIC STUDIES OF Cu(Ⅱ)-EDTA-HCHO ELECTROLESS COPPER PLATING SYSTEM

TAN MINGWEI, XU MIN

1993, 11(4):  316-320. 

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The kinetic behavior of the cathodic reaction and the anodic reaction during Cu(Ⅱ)-EDTA-HOHO electroless copper plating has been investigated. The dependence of surface concentration of CuEDTA^2-, which is reduced to form copper and covered on specimen, on plating time has been determined. The values of stable plating rate calculated from the equation expressing the relation between the stable plating rate and the equilibrium surface concentration of OuEDTA^2- are quite consistent with the corresponding measured values. Finally the actual reaction order of electroless copper plating has also been obtained.

INELASTIC SCATTERING BY ACTIVE MOLECULES EMBEDDED IN A SINGLE MODE OPTICAL FIBER

WANG ZHILIANG, LIN WEIGAN

1993, 11(4):  321-327. 

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By using the model of equivalent dipole of active molecules, and on the basis of the method of dyadic Green's functions and the expansions of the fields in terms of vector cylindrical wave functions, the analysis of the inelastic scattering by active molecules embedded in a single mode optical fiber is given. The analytical expressions and the numerical results of the scattering coefficients for the inelastically scattered guided HEn modes are obtained. The problem of coupling between the elastic even(odd) and inelastic odd (even) HEn modes is considered at the same time.

APPLICATION OF SBR——CALCULATING THE RCS OF AN ARBITRARY SHAPED OPEN-ENDED CAVITY

XIAO GAOBIAO, ZHANG JUN

1993, 11(4):  328-332. 

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The main idea of SBR——shooting and bouncing rays——is discussed in this paper. Using SBR, the EOS of a complicated S-shaped open-ended cavity is calculated. The cavity, with two layers of absorber-lining,has a nonuniform cross section. The cavity curvature is fitted with a series of waveguide configurations, the fitting functions being the simple ones. It is found that the calculated results are in agreement with the measured results.

STRUCTURE DETERMINATION OF (CdTe-ZnTe)/ZnTe/GaAs(100) SUPERLATTICE BY X-RAY DIFFRACTION

ZHONG FUMING, CHEN JINYI, ZHU NANCHANG, LI JIE, YUAN SHIXIN

1993, 11(4):  333-336. 

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The X-ray diffraction (XRD) method was used in the investigation of the structure of (GdTe-ZnTe)/ZnTe/GaAs(100) strained-layer superlattice. The diffraction profile was analysed by means of the X-ray diffraction theory and computer simulation to obtain the structure parameters and information.

PARTLY CHIP BREAKING CHARACTERISTIC IN VIBRATION DRILLING

ZHANG DEYUAN, WANG LIJIANG

1993, 11(4):  337-344. 

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Up to the present, all published vibration drilling chip breaking theories considered that in zero-phase-difference axial vibration drilling, chip breaking was impossible. This point of view was found improper by our experiments.
From tho point of view of kinematics, axial cutting depth at each point of the major cutting edge remains unchanged during the cutting process under ordinary conditions; chips would not be broken. However, when some ductile metals, such as industrial aluminum, are vibration drilled with relatively large vibration amplitude, special chip breaking phenomena appear, which favours the drilling process very much. Proceeding from the changing angle characteristics of vibration drilling, this paper proposes the new chip breaking theory, and some experimental investigations have been made.

THEORETICAL EXPRESSION OF THE SPECIFIC HEAT OF WOOD

YANG QINGXIAN

1993, 11(4):  345-352. 

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In this paper, the theoretical expression of the specific heat of wood is set up from the microstructure of wood and by applying some basic principles of physicomechanics. when the theoretical values of specific heat of 27 different species of wood with different moisture contents and temperatures are compared with the experimental values in the same conditions, it has been discovered that the maximum error is less than 11%, and the average error is within 5%.

NONLINEAR SENSITIVITY ANALYSIS FOR RESERVOIR OPTIMUM INTERPRETATION

GUO KE, LU YANG

1993, 11(4):  353-359. 

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At present, the optimum method is the method used by oil-fields to reflect the physical parameters of the reservoir. But when the design variates and the suitable constraints happen to perturb, unstable optimum solution and unsatisfactory reservoir interpretation result. In this paper, to solve the problem, the nonlinear sensitivity theory is applied to design a low sensitivity model for the reservoir optimum interpretation. This model reduces interference greatly. Compared with the practical data drawn from a few wells, the results from the computation are satisfactory.

Research Notes

INVESTIGATION ON PREPARATION OF SUB-MILLIMETER POLY-SILICON GEAR

ZHAO XINAN, SU YI, ZHANG XI, TAN SONGSHENG, WANG WEIYUAN

1993, 11(4):  360-365. 

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A poly-silicon micro-gear of 400μm in diameter and 5μm in thickness with a gap of 3.5μm between the gear and the shaft has been successfully fabricated by using 10 planar technology. A gear train of the same size is also given. And the influences of plasma etching conditions on the technology are discussed.

ELECTRON MICROSCOPIC OBSERVATION OF POLYMERIZATION PROCESS OF HYDROLYSIS PRODUCTS IN ZrOCl₂ SOLUTIONS DURING BOILING

HUANG YUEXIANG, GUO CUNJI, XIE YIFEN

1993, 11(4):  366-370. 

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The polymerization process of hydrolysis products in ZrOCl₂ solutions under boiling condition has been investigated by tha electron microscopic tachnique. The results show that there exists a palymarization process in ZrOCl₂ solutions with different concentrations. First a number of crystal nuclei are formal which grow gradually to definite-sized, definite-shaped multimorphous particles through the process of polymerization. Tha urea additive has been proved to promote the polymerization process. The synthesized particle size mostly depends on the concentrations of the initial ZrOCl₂ solution and the boiling time. The higher the concentration and the longer the boiling time, the larger the obtained particle size. So the particle size can be controlled by selecting the suitable initial concentration and boiling time.