Table of Content

31 March 1995, Volume 13 Issue 1

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Articles

OBSERVATIONO OF LB FILMS BY ATOMIC FORCE MICROSCOPY (AFM):FROM MICRON DOWN To MOLECULAR SCALES

YANG XIAOMIN, GU ZHONGZE, WEI YU

1995, 13(1):  1-6. 

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The atomic force microscopy (AFM) was used to observe the microscopic structure of stearic acid LB films deposited on solid substrate,the range being from micron down to molecular scales.The AFM images show the surface morphology of the film intermolecular arrays as well as film defects.By increasing the applied force from the AFM tip, we can make a pattern on LB films and directly measure the thickness of the monolayer.

THE ADJUSTING PROCESSING OF THE MEASURING OF FLATNESS AND ITS MICROCOMPUTER REALIZATION

HOU BOJIE, XIONG YOULUN, LI XINSHENG, ZHOU HUIXING

1995, 13(1):  7-13. 

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The method for the adjusting processing of the flatness error measurement is The flow chart of a high-LeveL microprogramming language foreveral indirect measurement methods is given.

MODEL RESEARCH OF THE FUSED TAPERED OPTICAL FIBER COUPLERS

GU BIXGSHENG, ZHANG JIALUN, SHEN WENDA, LI QINGNING

1995, 13(1):  14-20. 

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We Proved theoretically that the week guiding and weak coupling approximatlon must be untilized when our approximate parallel waveguide model takes the place of the original model of the fused tapered wide band coupler.According to the experiment on the weakly fused tapered coupler developed by us,we obtained that the fused tapered wide band coupler with a shape of dumb-bell satisfied the weak guiding and weak coupling conditions.Furthermore,according to the curve of the translation power versus the wavelenth,we obtained that not only the theoretical curve reflecting the wide band characteristic matched well with the experiment curve,but the coupling characteristic was very sensitive to the ratio of two fiber cores and fused length,a fact identical with the practical result.

CHARGE DYNAMICS OF SILICON DIOXIDE ELECTRETS

XIA ZHONGFU, LU METAN, P Guenther, SHI LINSHENG

1995, 13(1):  21-28. 

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In this paper,the transport rule of detrapped charges (either negative surface charges or positive surface and bulk charges) in the bulk of the silicon dioxide film electrets was systematically studied. The discharge behavior of silicon dioxide electret,the influence of chemical surface treatment on charge stability and the shift of charge layer in the bulk for SiO₂ were investigated. The mean charge depth can be shifted from the near free surface into the bulk of SiO₂ by control-ling the ageing temperature. The negative charges in the bulk of silicon dioxide have excellent stability,which is a very important result for the study being done about the improvement of quality for SiO₂ micro-sensors.

MONTE CARLO SIMULATION OF ELECTRON BEAM SCATTERING TRAJECTORIES IN LB RESISTS AND SUBSTRATE AND THE SUPERIORITIES OF LB RESISTS FROM BACK-SCATTERED YIELD

LU WU, GU NING, LU ZUHONG, WEI YU

1995, 13(1):  29-34. 

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The actions between electrons and atoms of resistS or substrate in electron beam exposure are studied in this paper by applying the Monte Carlo method. The scatter trajectories of electrons in PMMA (polymethylmethacrylate) resists Prepared by Langmuir Blodgett (LB) techniques or spining cast on Si substrate or Si substrate covered with Cr film and the back-scattered yield have been calculated in different conditions. A refraction model of high-energy electron in multilayer medium has been put forward to describe the changes of scatter distance and scatter angle of the electron when it comes from one layer into another layer. The results prove that there is a smaller back-scattered yield in LB resists for electrons and the purpose decrease the proximity effect can be reached no matter whether lower or higher energy iS adopted in electron beam LB resist exposure.

AN INVESTIGATION OF PLASMA SPECTRUM IN THE PROCESS OF DIAMOND THIN FILM DEPOSITED BY MPCVD

ZHOU MINGHUA, XI YIBEN, ZHANG XUBAI, WANG HONG

1995, 13(1):  35-38. 

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The character of the average energy of the electrons in the plasma ball generated by microwaves is studied by observing the spectrum of the plasma ball under different depositing conditions.The mechanism of deposition is discussed by analyzing the collisions between electrons and hydrocarbon molecules and the change of the hydrocarbon radicals' energy.

X-RAY DOUBLE-CRYSATL DIFFRACTION SPECTRUM OF RAPID THERMAL ANNEALED Si⁺ IMPLANTED GaAs

GU HONG, XIA GUANQUN, CHEN JINGYI, ZHU NANCHANG, SHENG HONGLIE, ZHOU ZHUYAO

1995, 13(1):  39-45. 

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GaAs films are implanted with Si ions at 180 keV with doses of 5×10¹²/cm²~10¹⁵/cm² and then rapid thermal annealing is Performed by incoheret light.The strain and doping mechanisms are studied by double-crystal diffractometry in connection with backscattering and Hall measurement.The compensation ratios are calculated by using the Mobility theory.
The results suggest that when implanting at low doses,the amphoteric property of Si plays the main role in the activation effcieney, and that at high implanting doses the low electrical activation is caused by the presence of interstitial Si.

THE OPTIMAL DISCRETIZATION SCHEME FOR TWO-DIMENSIONAL CURRENT CONTINUITY EQUATION

TENG ZHIMENG, HE YE, DING XINFANG, WEI TONGLL, TONG QINYI

1995, 13(1):  46-50. 

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This paper presents a simple and novel finite difference scheme for the two-dimonsional current continuity equation, which can preclude nonphysical oscillations and effciently reduce the crosswind effect.In comparison with the classical multidimensional S-G scheme and the SUPG scheme the present scheme exhibits bettr numerical properties,so it can be applied in computer simulation of semiconductor devices.

A DIRECT COMPARATIVE INTERPRETATION FOR DIFFRACTION OF PARTIALLY COHERENT LIGHT

E GUOGUANG

1995, 13(1):  51-62. 

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Assuming paraxial approximation and quasi-monochromacy,the diffraction of Partially Coherent Light is investigated.It has been verified that the intensity distribution in the diffraction pattern is proportional to the convolution of the intensity distribution,due to a monochromatic point light source and a Fourier transformation of Mutual Coherence Function in the test plane.This result is valid in both diffraction cases:i,e,in the near field, as well as in the far field.Especially,the effect of the Mutual Coherence Function on the spectrum of intensity distribution of ideal diffraction is also discussed after the contrast function is introduced.

SOLIDIFICATION STUDY ON NON-HEAT-TREATMENT HIGH CARBON HIGH MANGANESE STEEL AND ITS APPLICATION PROSPECTS

SHI ZHONGLIANG, LI SHAOXIONG, YIN YANSHENG

1995, 13(1):  63-68. 

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Carbide formation and its morphology of high manganese steel have been further researched in the light of nonequilibrium solidification (liquid-quenching and casting).It has been found that carbide can be formed and its growth abides by the branohing cooperation growth mold.It is put forward that the carbide growth can be improved by modification treatment,the branching growth carbide can be turned into spheroidite,which is proved by the test of Si-Ca modification treatment of high manganese steel.The reason is that the content of active trace elements,surphur and oxygen,and their distribution have changed.The results will provide theoretical and practical bases for as-cast high carbon high manganese steel product development and application.

STUDY OF THE PROCESS OF COPPER-PLATING ON BASE-METAL IRON

WANG CEAOMIN, FENG SHAOBIN

1995, 13(1):  69-73. 

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In this paper,the process of copper metal electrodeposit in the electrolysis bath was studied by the constant current and the encircled volt-ampere methods.it was observed that the iron electrode surface was first activated and then the metal was separated out along with potential negative shifting.Thus the high strength combination between the plating deposit and the iron substrate is achieved.

THE TENSILE STRENGTH AND FRACTURE PROPERTIES OF THE COATED CARBON FIBERS

CHU SHUANGJIE

1995, 13(1):  74-80. 

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In the paper,with the help of the CVD method,the author acquired uniform SiC coating,C+SiC composite coating,Si coating and C-Si gradient coating on the surface of carbon fibers (CF);studied the influence of the coating on the tensile strength of CF; analysed the phase structure of the coating and studied the fracture process and fracture texture.Experimental results show that the tensile strength of the coated CF is lower than that of the acetone treated CF;that the sequence of the tensile strength magnitude of the coated CF is from the C-Si gradient coated CF to the C+SiC composite ccated CF,tO the SiC coated CF,and to the single Si coated CF;and that the phase structures of all coatings on the surface of CF are noncrvstalline,The author further proved "the turbostratic graphite structure" of the PAN Ⅱfiber,The characterizations of appearance of the fracture of PAN fiber are the step form wave form,buckle form, car arm form,etc,respectively.The appearance of the fracture of the C-Si gradient coated CF,the C+ SiC composite coated CF and the SiC coated CF is in the flat cutting form; the fracture mechanism is that the craze spreads throngh the CF. But the appearance of the fracture of the single Si coated CF is in the pull-out form; the fracture mechanism is that the craze spreads along the interface of the coating,the CF is split.

PARALLEL CORE CONSTANTS

YAO KAIYI, SHEN JIANGGAN

1995, 13(1):  81-87. 

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This paper introduces the definition of parallel core constants,and describes the necessity of the introduction of these constants,the source of these constants and their calculations.At the end of the paper,there are some examples for the application of these constants.The results consist extremely well with practice.

ANALYSIS OF HEAT AND MASS TRANSFER AND REFRIGERATING PERFORMANCE IN POROUS WINDOW

ZHANG ZHE, LIU WEI, WANG CHONGQI, CHENG SHANGMO

1995, 13(1):  88-94. 

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In this paper,from the macroscopic continuum approach,a set of general equations are established to describe the heat and mass transfer through unsaturated porous media.The SIMPLE method is adopted to solve the governing equations for the two-dimensional porous window model.The field distributions of variables in the porous bed and the heat flux between the porous window and the environment under different working conditions are obtained by numerical simulation.The results show that the mathematical model and the numerical method are reasonable and feasible,and that the heat taken out of room by the porons window is capable of meeting some air-conditioning needs.The relation between the environment parameters and heat-mass transport in the porous bed and the heat exchange capability of the porous window are also analyzed.

THEORETIECAL PRINCIP LES AND CONTROL TACTICS ON MECHANISMS OF ACTIVE VIBRATION CONTROL USING AN ELECTROMAGNETIC ACTUATOR

ZHU MEILING, WANG FENGQUAN, YAN JINGPING, XU SHANGXIAN

1995, 13(1):  95-102. 

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The mechanisms of active vibration control using an electromagnetic actuator are investigated in this paper.The system test model is built.The vibration transmissibility is derived from the model by means of transfer function analysis.To determine the limited gain values of various feedback variables,the stability analysis of the active control system is carried out The vibration-isolation characteristics of the active vibration control system of the single freedom degree are discussed using an electromagnetic actuator for various variables and various feedback gain valnes with computer simulation.It si shown by analysis results that the combined feedback variable method based on absolute position,absolut evelocity and relative position variables has an effective vibration isolation property even in the condition of the low and wide frequencies.

A PRECISE METHOD OF CALCULATING THE PARAMETER ε-THE MEAN STRAIN RATE IN ROLLING

ZHAO DEWEN, TIE WEILIN

1995, 13(1):  103-108. 

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With an accurate parametric equation of the contact arc,the kinematically admissible velocity and strain rate fields are established in this paper.A precise formula to calculate the average strain rate in rolling is dedued by the parametric integral and the integral mean value theorem.It is compared with the traditional formulas through an actual measured example.

A B-SPLINE METHOD FOR SMOOTHING TURBINE BLADE CONTOURS

WEI YUANQIAN

1995, 13(1):  109-115. 

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This paper chiefly researches on some conrete applications of a B-spline method for smoothing turbine blade contours.

THE EFFECT OF DIRECT COUPLING ON THE FMCW RADAR AND THE METHOD OF ELIMINATING THE EFFECT

YU SHUNDE, ZHU WEIZHONG

1995, 13(1):  116-120. 

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Thie article,using the spectrum analytic method,analyses the effect on the actual sensitivity of the receiving system of the FMCW radar.The effect is produced by the direct coupling of the transceive antenna,the feeder leak and the refiection of environmental objects.The method for the elimination of the effect is offered.

THE PROPERTIES OF COERCIVITY OF FRACTAL AGGREGATES FORMED BY MAGNETIC PARTICLES

WANF QIAN, SAUN QIANG, DENG ZHAOJING

1995, 13(1):  121-126. 

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In this paper, the effect of fractal dismension (D) in coercivity (H₀) of single-domain particle aggregates is discused. Making use of dpole field approximation,an expression relatng D and H₀ is derived,which states that H₀ is a deoreasing function of D. By analyzing the relati n between D and packing density (p),it is found that th.obtained conclusion is consistent with the existing theoretical and experimental results.