Table of Content

31 December 1996, Volume 14 Issue 4

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Articles

THE INFLUENCE OF ANNEALING PROCESS ON THE CHARGE STORAGE IN HyBRID FILM ELECTRET PVDF/SiO₂

BAI WEI, YANG DABEN

1996, 14(4):  379-384. 

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In this paper,the influence of annealing process on the charge storage and stability in hybrid film electret PVDF/SiO₂ was studied by means of surface potential decay and TSD-spectra. The properties of the film, before and after annealing, were discussed by means of infrared spectrum analysis. The experimental results show that electret properties of the sample were improved after annealing.

EFFECTS OF THERMAL HISTORY ON MECHANICAL PROPERTICS OF AGGLOMERATE-FREE SiC_(p) REINFORCED SIALON COMPOSITES

LIU QIAN, GAO LIAN, YAN DONGSHENG, H MANDAL, D P THOMPSON

1996, 14(4):  385-390. 

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Densified SiC_(p) reinforced Ln-Sialon(Ln-Nd and Yb) composites were fabricated to evaluate the improvement in microstructure and mechanical properties that can be achieved by α→β transformation induced by heat treatment.Nd-and Yb-Sialon/SiC_(p) composites possess quite different reactions to thermal history. Under the same conditions for heat treatment, α phaso is quitg unstablein the Nd-Sialon/SiC_(p) system and almost thoroughly transforms to β phase, with aluminum-containing melilite(M') left at pockets of grain junctions as a dominant grain boundary phase. Despite a great many elongated β grains,existing in the Nd-system, fracture toughness (K_IC) was not improved because the decrease of aspect ratio and occurrence of coalescence of grains caused by a longer heat treatment might degrade mechanical properties, especially K_IC values. Comparatively speaking, Yb₂O₃ is a kind of better densifying additive for the composites and more efficient to stabilize α structure than Nd₂O₃. As a result, Yb-Sialon/SiC_(p) composited possess higher hardness (H_v) owing to a lot of equiaxed α grins developing in the materials.

LIQUIDUS CURVES OF THE HIGH-TEMPERATURE PHASE FIELDS IN THE Ti-AI SYSTEM

LI WEN, ZHANG JIANMIN, GUAN ZHENZHONG, JIANG QING, SHEN PING, ZHANG RUILIN, YU RUIHUANG

1996, 14(4):  391-397. 

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According to the EET and CVM, liquidus curves of the high-temperature Phase fields in the Ti-Al system are calculated,the effects of interstitial impurities on phase transformation are analyzed, and then some Present doubtful experimental resul ts are explained.

RESEARCH OF ELECTRONIC STATES OF IRON IONS IN Fe₃O₄ BY MEANS OF XDAFS

YANG CHUANZHENG, HAN DINGDING, ZHU HONGME

1996, 14(4):  398-402. 

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XANES spectrums of Fe₃O₄ have been determined by means of X-ray diffraction anomalous fine structure (XDAFS) with synchrotron radiation. The valley position of the 400 diffraction is a side of the high energy of the 220 valley position. The displacement quantity is about 1.4eV. This result shows that electronic states of two kinds of iron ions which lie in the different equivalent lattice positions in Fe₃O₄ are different.

THE EXPERIMENTAL STUDY ON GROWTH PROCESS OF CoSi₂/Si HETERO-EPITAXY By Co/Ti/Si MULTILAYER SOLID STATE REACTION

WU WEIJUN, LI BINGZONG, SHAO KAI, FANG HUA

1996, 14(4):  403-408. 

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CoSi₂ is being ivestigated intensively for microelectronics application recently. lit this paper a new method of growing an epitaxial CoSi₂ film by the solid state reaction of Co/Ti/Si and TiN/Co/Ti/Si multilayer is described.The variation of structure and sheet resistance of the film with thermal annealing temperature and time is studied. The kinetics and mechanism of the CoSi₂/Si solid-phase epitaxy are discussed.

1/f NOISE AS A PREDICTION OF THE STORAGE LIFETIME FOR BIPOLAR TRANSISTORS

ZHUANG YIQI, SUN QING

1996, 14(4):  409-414. 

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It is Shown from storage lifetime test and low-frequency noise measurement for bipolar transistors that the degradation of current gain β occurs for most of the tested devices and is strongly correlated with the initial 1/f noise in thsse devices, So the 1/f noise measurement can be used as a fast and non-destructive tool to evaluate the storage lifetime of the devices. The experimental and theoretical evidences as well as a Prediction model for the new method are presented in this paper.

DELAYTIME ANALYSIS FOR SUPER HIGH SPEED BICMOS DIGITAL CIRCUITS IN LOW TEMPERATVRE

Wu JIN, WEI TONGLI

1996, 14(4):  415-421. 

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BiCMOS technology.has a most important effect in realizing super high speed circuits systems. On the basis of the conventional BiOMOS theory, a unified non-linear analytical delaytime model for BiCMOS digital circuits is presented by fully considering some low temperature effects, such as current driving capability enhancement of MOSFET, current gain and cutoff frequency decadence, forword turn on voltage of emitter-base junction increment of BJT,and the junction capacitance reduction of the system. The conculsions obtained have important significance in the optimization design for low temperatures super high speed BiCMOS circuits.

INVESTIGATION OF 3mm WAVE WIDEBAND VARACTOR-TUNED HARMONIC OSCILLATOR

FAN YONG, WU ZHENDE, TANG XIAOHONG

1996, 14(4):  422-426. 

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Based on the principle of "electronically tuning the fundamental frequency and extracting the second harmonic",the paper proposes a circuit model for the wideband series varactor-tuned harmonic oscillator. At W-band the electronic tuned bandwidth of 15% is achievevd within which the minimum power is 5mW and the maxmum over 17mW. The electronic tuned bandwidth of Dyer 5mW is found to be 13GHz.

PRESSURE EFFECT OF Fe-29wt% Ni ALLOY ULTRAFINE PARTICLES

CHEN YUNHONG, CHEN QINGIU, DENG GUICHANG, LU HUAIXIAN, DU YOUWE

1996, 14(4):  427-431. 

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Fe-29wt% Ni alloy ultrafine particles with different average sizes are prepared using the evaporation-condensation method. Under different pressures, the ultrafine particles are compressed into round small rings.As the pressure increases, martensitic volume fraction and specific saturation magnetization,σ_s, exhibit amarked increase,whereas corecivity, H_c shows a linear decline. The complex permeability varies with the Pressure. Its high frequency characteristic is much superior to that of the bulk.There is a close relationship between for pressure effect and the average size, d.

EVALUATION OF SPLICE LOSS DUE TO SIMULTANEOUS ANGULAR AND TRANSVERSE MISALIGNMENTS BETWEEN TWO NONIDENTICAL GRADED-INDEX PLANAR OPTICAL WAVEGUIDES

WANG ZIHUA

1996, 14(4):  432-436. 

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An efficient method has proposed for evaluating the splice loss between two nonidentical arbitrarily graded-index singlemode planar optical waveguides.The power transmission coefficients are expressed as the sum of Hermite-Gaussian functions, and then the overlap integrals can be calculated analytically. Numerical examples have been given and the influence of waveguide parameters and the individual misalignment on splice loss is discussed. We have checked the accuracy of approximating the load due to both defects by adding the losses due to each individual defect.

CROWTH AND CHARACTERIZATION STUDY ON AgGaSe₂ CRYSTAL FOR NONLINEAR INFRARED APPLICATIONS

ZHU SHIFU, ZHAO BEIJUN, LIU JUN, LI ZHENGHUI, JIANG HONGAN, LI WEITANG

1996, 14(4):  437-440. 

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A Perfect,crack-free single crystal of AgGaSe₂ of 20mm in diameter and 55mm in length is grown by a modified Bridgman-Stockbarger technique in the two-zone vertical furnace. A sample of sibs of 10min×10mm×9mm is cut along the (101) cleavage plane. It is found by the IR microscope that there are few inclusions and defects in the crystal. The transmission is 62% and the absorption coefficient is 0.05 cm^-1 at 10.6 μm, respectively. The thermal etch pits and corrosion stripes are observed by the Scanning Electron Microscope.

NEW MEASURE ON BLANK SCRAP UPCOING THE PRINOIPLE AND NEW DIE DESIGN

LU XIANFENG, TAKEO NAKAGAWA

1996, 14(4):  441-446. 

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A new research result has been introduced to the Problem on blank scrap upgoing in automation presswork. The restraint principle which relies mainly on increasing the frictional force is put forward. And by direct comparison of the experimental methods, a new inverse conical die and its design gist are recommended in this Paper. The research result has important significance to the development of automation presswork in the 21st century.

PI TYPE EXTENDED PREDICTION SELF-ADAPTIVE CONTROLLER AND ITS APPLICATON RESEARCH ON PAPER MACHINE PROCESS

OHEN ZENGQIANG, YUAN ZHUZHI

1996, 14(4):  447-452. 

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This paper establishes a kind of extended predictive self-adaptive controller which has the PI structure, (PIEPSAC). Simulation research is done on the mathematical model of wet-base and paperpulp flow in a paper-making process. The simulation result demonstrates the excellent control effect of this kind of controller.

THE EFFECT OF CONSTRUCTIONAL PARAMETER ON THE PERFORMANCE OF THE ENDOREVERSIBLE CARNOT HEAT PUMPS

YAN ZIJUN, XU YUMEI

1996, 14(4):  453-456. 

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This paper studied the effect of the finite constructional parameter on a class of endoreversible Carnot heat pumas with pitons. We used an ideal gas working substance and the crank linked up with the Pump rotated uniformly.The fundamental optimal relation of the pumps was derived, and some significant discussions were made. Some more instructive new conclusions for the real heat pumps were obtained.

HIGH PRESSURE EFFECTS ON THE DIFFUSED PHASE TRANSITION OF Pb (Fe_1/2Nb_1/2)O₃-Pb(Fe_2/3W_1/3)O₃ CERAMIC

ZHANG YIBING, WANG BO, JIN BIANJUN, CHENG DAREN

1996, 14(4):  457-462. 

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The dielectric constant ε of Pb(Fe_1/2Nb_1/2)O₃-Ph(Fe_2/3W_1/3)O₃ binary system has been measured at high hydrostatic pressures from 0 to 14kbar and temperature from -190℃ to 100℃. The experimental results indicate that temperature and pressure-induced phase transitions are diffused. With increasing pressure, the phase transition temperature T_m drops linearly with dT_m/dP=-3.1℃/kbar, maximum permittivity ε_max decreases, and the diffusion degree of the phase transition increases. These properties of diffused phase transition at high pressure are discussed phenomenologically in this paper.

A SIMPLE FORMULA FOR CALCULATING THE PRESSURE IN HIGH PRESSURE TANK

CAO ZHIJUE, HE XIANCAI

1996, 14(4):  463-465. 

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A simple formula for calculating the pressure and temperature in a high pressure tank is worked out not by making concrete calculation of configuration integral, but by using the basic formulas for the canonical ensemble. And the difference between the result worked out by this formula and that made by tests is very small. Applying this formula to engineering thermophysics can reduce the time of tests.

NUMERICAL MODELLING OF THE TWO-DRIVING SPLITTING STIRLING REFRIGERATOR AND COMPARISON WITH THE EXPERIMENTAL TEST

HE YALING, XU MINGYAO, HUANG WEI, WU PEIYI, SHAO XIMING, XIN JINKANG

1996, 14(4):  466-468. 

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The numerical modelling of the thermodynamic and dynamic parameters of the two-driving splitting Swirling refrigerator is suggested in this paper. The calculated results are compared with the experimental results. It is shown that the calculated results are consistent with the experimental ones.

STUDY OF WAVE-LIKE PHENOMENA IN REMOTE FIELD EDDy CURRENT NONDESTRUCTIVE TEST PHASE VELOCITY RESDARCH

ZHAO YANG, CHEN MEIJUAN, SHI DANING

1996, 14(4):  469-474. 

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The numerical simulation and theoretical analysis for Phase velocity properties of the remote field eddy current(RFEO) is presented in the paper by the electromagnetic (EM) field theory and EM computation. Comparisons of the phase velocities between the EM field and the EM wave are given. It can be seen that the research of RFEC in thin paper is of importance for Promoting the application of the RFEO technique to practical use.

LANGMUIR PROBE AS A DIAGNOSTIC TOOL FOR PLASMA IN VACUUM ARC COATING(VAC) PROCESSES

OHENG ZHONGYUAN, ZOU JIYAN, YANG LEI, ZHANG HANMING

1996, 14(4):  475-480. 

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This paper discusses the feasibility of using the Langmuir probe as a diagnostic tool for plasma in Vacuum Arc Coating (VAC) processes, and the validity of probe theories in this situation. A system has been set up for the in situ diagnosis of VAC plasma. Plasma parameters have been diagnosed nuder various process parameters.

STUDY ON SURFACE MORPHOLOGIES OF POLYCRYS TALLINE SILICON AND ALUMINIUM SILICON ALLOY BY ATOMIC FORCE MICROSCOPY

WU JINGWEN, LU ZHUHONG, WEI YU, ZHU WEIMING

1996, 14(4):  481-487. 

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In this Paper, we studied the surface morphology of Low Pressure Chemical Vapor Deposition (LPCVD) polycrstalline silicon at different deposition temperatures by Atomic Force Microscopy (AFM).We found when the deposition time was the same, the grain size and microroughness increased with the increse of the deposition temperature. In addition, we also studied the morphology of magnetron sputtered aluminium silicon alloy at different sputter temperatures by AFM. We found the irregular-shaped grains tilting in varying degrees and piled up in space at 0℃ and the irregular-shaped grains joining together on a plane at 200℃. Furthermore when the sputter temperature was 400℃, the grain size turned to be square-shaped.

A NOVEL METHOD OF RF SPUTTERING FOR FABRICATION OF 10.6μm Ge-Ag-Ni HOLLOW WAVEGUIDE

YE YUTANG, YE LINA, WANG RUIFENG, CHEN GUANHUA, SHEN XIAO, HONG YONGHE

1996, 14(4):  488-492. 

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A novel method of RF sputtering is discribed. The usefulness for the fabrication of the 10.6μm Ge-Ag-Ni hollow waveguide with a small diameter of the method is discussed. Some samples have been fabricated using the method and the transmittance of the samples with different waveguide diameters is presented.

TWO INEQUALITIES FOR THE DETERMINANTS OF H-MATRICES

HUANG TINZHU, YOU ZHAOYONG

1996, 14(4):  493-497. 

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We study the inequalities of the determinant for H-matrices and obtain the Minkowski-type and convexity inequalities for two H-matrices A and B under certain conditions.