Table of Content

30 June 1987, Volume 5 Issue 2

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Articles

TRANSIENT EM FIELD

SHEN HAOMING

1987, 5(2):  95-103. 

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An introduction on transient EM field and EM pulse is presented. The application, properties, contents and methods of transient field are summed briefly.

STRESS INTENSITY FACTORS FOR AN ELLIPTICAL CRACK UNDER ARBITRARY NORMAL LOADINGS

OUYANG OHANG, XU LINLIN

1987, 5(2):  104-107. 

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In this paper, the stress intensity factors of an elliptical crack under arbitrary normal loadings are given with the expansions of displacement potentials in Lame functions.

INTERPRETATION OF 4.2 K PL SPECTRA OF CERTAIN DEFECTS IN GALLIUM ARSENIDE

ZOU ZHONGJI, ZOU YUANXI

1987, 5(2):  108-112. 

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We suggest an empirical method for interpreting the 4.2.K PL spectra of certain complex defects. The essence of this method is assuming a constant k to take care of the difference in photoluminescenoe efficiency of certain coexisting defects. Some useful results have been obtained by applying this method to the interpretation of the 0.65eV and 0.80eV bands in the PL spectra of undoped, SI LEO GaAs reported in the recent literature. It is shown that the use of this method helps to shed some light on the nature of the defects involved. This success reflects the reasonableness and usefulness of the proposed method in interpreting 4.2 K PL spectra of certain semiconducting compounds, especially GaAs. In addition, the present results also support the common origin hypothesis for EL2 and the arsenic antisite AsGa as well as the strain model for EL2 proposed by one of the authors in two previous papers.

FARADAY ROTATION IN MONOMODE FIBRES WITH AXIALLY VARYING MAGNETIC FIELD

QIAN JINGREN

1987, 5(2):  113-116. 

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The Faraday rotation is studied using the coupled-mode theory and a simple integral formula is derived for calculating the total Faraday rotation in a monomode optical fibre produced by an axially varying magnetic field. It is also found that Miller's method is particularly useful in calculating the Faraday rotation produced in a fibre with periodic couplings.

A SIMPLE AND CONVENIENT METHOD OF MEASURING COMPOSITION OF LiNbO₃ CRYSTAL

LIU SIMIN, ZHANG GUANGYIN, EONG FANG, WU SIJIA, KANG WIE, LIU QIUXIANG

1987, 5(2):  117-122. 

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The birefringence of LiNbO₃ crystals is measured using the method of laser "cone light" interference.. The precision is up to +0.001. Solid composition of LiNbO₃ crystal is then obtained directly by using the "birefringence-solid composition" curve of LiNbO₃ given by Oarruthers et al. It is found that this method is simple and convenient and is easy to practise. The precision is about an order of magnitude higher than that of chemical method.

ANALYSIS FOR DETERMINING DRAIN PIPE LOCATION AND SCALES ON MODEL MADE CRUCIBLES OF OPTICAL GLASS LIQUID

WU JUNPENG, YANG WENXIONG, YU NAIHUA

1987, 5(2):  123-130. 

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According to fluid mechanics, molecular diffusion and heat conduction, the paper offers a new theoretical analysis for determining the drain pipe location and its scales at a model-made crucible. This is very important in getting optical glass liquid of good quality. By calculating the glass liquid flow of a model-made crucible, we can determine the location of the drain pipe at the bottom of the crucible for eliminating "stripes" in the products.By computing the temperature field in the drain pipe, the paper yields the relationship among the minimum value of the length Lm, diameter D, Reynolds number Re and Prandtl number Pr of the glass liquid and offers a foundation for determining the length of the drain pipe. A calculation example and a formula for determining the diameter D of the drain pipe are given in the paper.It is believed that the analysis and calculation given here are of some value to designing mixers in chemical engineering industry.

APPLICATION OF SIGNIFICANT STRUCTURE THEORY TO THE STUDY OF THE TERNARY SYSTEM:BENZENE-CYCLOHEXANE-CARBON TETRACHLORIDE

YEN WENHSING, SUN YAPING

1987, 5(2):  131-137. 

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By its successful application to the study of binary system, the significant, structure theory was advanced to the study of the ternary system, benzene-cyclohexane-oarbon tetraohloride, in the evaluation of excess volumes, excess enthalpies and excess Gibbs free energies. The result agrees well with the published and calculated data.

EFFECT OF POLYSULFONE SEQUENCE LENGTH AND CONTENT ON THE PROPERTIES OF POLYSULFONE NYLON 6 BLOCK COPOLYMERS

DING YOUJUN, QIAN JINXIN, JI GUIJUN, XIONG WEI

1987, 5(2):  138-146. 

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A series of rigid-rigid polysulfone-nylon 6 (PSF-N6) block copolymera containing polysulfone and nylon 6 segments of varying molar composition have been synthesized. The effect of PSF equence length and content on the prooessibility, heat-resistance, water-absorption and mechanical properties of the PSF-N6 block copoly-mers were studied.
It has been shown that the processibility of the copolymer decreases when the amount and M. W. of PSF increases in the copolymers, and the glass transition temperature increases monotonically as a function of polysulfone content. As the polysulfone content increases, water-resistance of the copolymer increases, and the modulus decreases.Due to the semi-crystalline nature of PSF-N6 block copolymer, the solvent and environmental stress crack resistance of the copolymers are significantly improved comparing with that of the polysulfone homopolymer. The copolymers are more formic acid resistant than N6, presumably due to the introduction of polysulfone segments.

EDTERMINATION OF PHASE DIAGRAM IN LOW LITHIUM REGION OF Li-Fe-S TERNARY SYSTEM BY ELECTROCHEMICAL TECHNIQUE

WEN TINGLIAN, W. WEPPNER

1987, 5(2):  147-151. 

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A solid state galvanic cell has been employed to determine the phase diagram of the ternary system Li-Fe-S in the temperature range from 360 to 550℃. Li₄SiO₄ +40m/o Li₃PO₄ was used as an electrolyte. According to the general principle to investigate the phase diagram with electrochemical coulometrio titration, the samples do not have to be quenched and only electrical quantities are required to be measured. Thus, the partial phase diagram of ternary system Li-Fe-S for the region of lithium content lower than 10 atom% and Fe:S atomic ratio bigger than 47:53 has precisely been constructed.

MAGNETIC PROPERTIES AND THERMAL STABILITIES OF AMORPHOUS (Fe_1-xNb_x)_84.5B_15.5 ALLOYS

SHEN BAOGEN, ZHAN WENSHAN, ZHAO JIANQAO, CHEN JINCHANG

1987, 5(2):  152-158. 

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The ribbons of amorphous (Fe_1-xNb_x) _84.5B_15.5 (x=0,0.02, 0.04, 0.06, 0.08, 0.1) alloys were produced by melt spinning. The saturation magnetization at 12 K Oe were measured with magnetic balance in the temperature range of 77-1200 K. Experimental results show that the curie temperature, T_c, linearly diminishes with increasing Nb content of the alloy, the rate of which is about l7.6 K/at% Nb.

ELECTRICAL SWITCHING EFFECT IN SOME TCNQ-ION-RADICAL SALT POWDER COMPACTIONS

GUO DING, YE CHENG, YANG DALIN, QIAN RENYUAN

1987, 5(2):  159-163. 

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Among 31 TONQ-ion-radical salts, electrical switching has been observed in powder compactions of Li-TONQ, Mn (TONQ) ₂·3H₂O, Cu-TCNQ, Cu (TCNQ) ₂, Zn (TONQ) ₂.xH₂O and Ag-TONQ. These TONQ-ion-radical salt powder compactions were of 5 or 8mm diameter and approximately 300-600 μm in thickness with evaporated On and Al electrodes. The current-voltage characteristics revealed an abrupt decrease in resistance from 10⁴-10⁵ to 10²-10³ at a threshold voltage of 5-8 V. The ratio of R_off/R_on is tens to thousand times.

THE MEASUREMENT OF MINORITY CARRIER DIFFUSION LENGTH IN N LAYER OF N/P EPITAXIAL SILICON WAFER

YANG HENQING, WANG ZHIWEI, BAO ZENGMING

1987, 5(2):  164-171. 

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Using the photovoltaic spectral response of epitaxial P-N junction, the paper suggests a method of determining the minority carrier diffusion length in N layer of N/P epitaxial silicon wafer. The authors made a group of diagrams which contained the information of minority carrier diffusion lengths in the epitaxial layer and the substrate according to the theoretical analysis. When there is a thermal SiO₂ thin film on the surface of the sample, the photovoltage of the sample depends on the characteristics of the epitaxial P-N junction.

THE MANUFACTURE OF ALCOHOL-SENSITIVE ELEMENT

HUANG GUOFANG, CHEN WEIKANG

1987, 5(2):  172-175. 

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By means of CVD method, the thin film of tin diohloride doped with a single foreign ion is deposited on the purified ceramic substrate. The raw material of the element is anhydrous tin tetrachloride doped with single foreign ion. The range of working temperature of the element is 250 to 360℃. In this range of temperature, the element can detect the existence of alcohol vapor of concentration 2r/ml in the air. The element is non-ohmic contact element. Its response time is about six minutes and its life time longer than 1,000 hours.

A NEW METHOD OF ELIMINATING WRONG ANSWERS FOR COMPUTER INDEXING THE LAUE PARTTERNN——THE ZONE RIGHT-HANDED METHOD

GAO XIANGHONG

1987, 5(2):  176-179. 

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The zone right-handed method is proposed. An example of application of this method to eliminating wrong answers for computer indexing the Laue partternn is presented. It is found that this method is more simple than Hart's method^[1].

A METHOD FOR FITTING ASYMMETRIC DIFFRACTION LINE PROFILE AND SEPARATING Κα DOUBLET

GUO CHANGLIN, LIU YUNJI

1987, 5(2):  180-184. 

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Generally, the X-ray diffraction line profile is asymmetrical. A method for fitting the asymmetric diffraction line profile and separating the asymmetric Κα doublet is presented in this paper. According to the diffraction line profile fitting experiments for various functions, a method of a weighted Gauss-Oauchy combination function for asymmetric X-ray diffraction line profile is suggested. It has been proved by practical calculations that when the asymmetric profile function is employedin fitting practical diffraction line, the method is simple and convenient with sati-sfaetorily precise results.

ON-LINE MEASUREMENT OF PAPER MOISTURE USING INFRARED MOISTURE METER

WANG JINSAN, YE ZENHUA

1987, 5(2):  185-188. 

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The infrared moisture meter (Model HWS) is an instrument for on-line measurement of moisture in paper. The absorption of two beams in the infrared range are compared using the infrared measuring method. The energy of one beam of wavelength 1.93 μm is absorbed by water molecules and is compared with the energy of a reference one of wavelength 1.78μm uninfluenced by water content. As the pathes of both rays through the tested material are the same, the ratio of the energies arriving at the detector is in direct relation to the moisture content of the material tested.
The infrared moisture meter has been operating continuously for two years with an aocurancy better than 0.5% H₂O.