Table of Content

30 June 1986, Volume 4 Issue 2

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Articles

A MATHEMATICAL MODEL FOR MICROBIAL MUTAGENESIS AND THE DESIGN OF MUTAGENIC BREEDING

LIU CHUIYU

1986, 4(2):  95-104. 

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The expression of mutagenesis on polygenic system which controls a quantitative character of microbe can be represented by a mixed distribution. A mathematical model for microbial mutagenesis on populational level is a uniform-mutagenic distribution (i. e. a mixed distribution of two normal distributions).

THE FUNCTION AND PROPERTIES OF SYNCHRONOUS PRECESSING ELECTRO-MAGNETIC FIELD IN FEL IN LONGITUDINAL UNIFORM FIELD

CHEKG GANZHEN

1986, 4(2):  105-110. 

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In this paper, an actual and effective realization of the principle of the FEL operation in a longitudinal uniform magnetic field is discussed. It recommends a synchronous spiral quasi-static electro-magnetic field and a synchronous spiral resonant cavity electro-magnetic field to be used as two kinds of energy compensation of FEL in a longitudinal uniform magnetic field, and a synchronous spiral static-electric field as a starting gyration and tapering gyration for electron beam. A brief description is given to their function, characteristics and feasibility.

MATHEMATICAL MODELS OF ROUNDNESS ERROR ASSESSMENT AND THEIR SOLUTION

XIAO DONG, LUO XINHONG, ZHU XUNSHENG

1986, 4(2):  111-117. 

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This paper discusses how to determine, according to the profile of a circular workpiece, the roundhesa errors with, respect to different kinds of reference circles. The mathematical models of these reference circles are strictly denned. The roundness error results are obtained by making use of the optimization technique. Some related problems are also discussed.

1-D IMAGING BY REFLECTION OF ACOUSTIC WAVE IN SEISMIC EXPLORATION

HUANG GUANGYUAN, XU WENTIAN, FU GUOHUA, QIU ZONGFANG, YANG BAOZHE

1986, 4(2):  118-125. 

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In this paper we present a new method to solve the inversion of 1-D wave equation for seismic exploration. This method is based on the principle of pulse variation given by Ref. 5 and is more efficient than the one given by Refs.3-4 Some examples show its feasibility.

THREE CATHODES OF TANTALUM COMPOUNDS FOR FIELD-EMISSION GUNS

JIANG XIANGQI, KATO TAKEO

1986, 4(2):  126-131. 

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Tantalum tips with radius 0.1-0.5μm had been prepared by electrochemical etching, and then field-emission cathodes of tantalum nitride (Ta²N) tantalum carbide (Ta C), and tantalum carbide-nitride (TaN_xC_y) with Ta-core were prepared by solidgas reaction on the surface of Ta tips. Typical field-emission patterns and work functions Regarding fild-emission characteristics were given. It is shown that tantalum compounds are promising materials for field emitters.

BOUND ELECTRON PAIRS IN ELECTRON BEAM

YE LUNYAN

1986, 4(2):  132-138. 

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This paper gives a quantum mechanical analysis of the interaction between the electromagnetic field and the electron beam of free electron stimulated emission devices or linear electron accelerator. It is believed that the electron structure of electron beam consists of bound electron pairs with zero spin and the electron pair has some properties of the boson.

THE INTERMODULATION CHARACTERISTIC AND THE OPTIMUM OPERATING POINT FOR SATELLITE TRANSPONDERS

YAN FANG

1986, 4(2):  139-149. 

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In this paper, a few recurrence formulas of the three-order mnltioarrier/total intermodulation-power ratio for different number of carriers through a satellite communication transponder are given.
Thus, a programme-calculated method for the optimum operation point is put forward. Some engineering design charts under the condition of different parameters of satellite communications are given. By means of the charts, the designers of the overall system can focus their attention tin analysis and comparison without being involved in complicated calculations.
Some examples are given for confirmation and application.

SOLUTION TO THE SURFACE IMPEDANCE PROBLEMS OF THE PERIODIC NOTCHED PLANAR STRUCTURE USING THE WIENER-HOPF METHOD

FENG ZUWEI

1986, 4(2):  150-157. 

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In this paper, the basic property of the electro-magnetic wave propagation on a periodic notched planar structure is analysed and is pointed out that it is often necessary to simplify this kind of problems into boundary value problems in the boundary impedance condition. The key to the problem is to determine the surface impedance, when the period of the structure is not too long and the notch wall sufficiently thin, we can define equivalent surface reactance by reference to the reflection of the plane wave, and the problem of periodic notched structure can be approximately solved according to the condition of the uniform surface reactance.
The approach of normal component of the electrical field on the periodic notched structure being expanded into the Fourier integral has been used and the functional equations are set up according to the boundary condition. Using the Wiener-Hopf method, expressions of the secondary field and reflection coefficients are obtained, and Finally the expression of the surface reactance is found. The measured results are in good agreement with those found by theoretical methods. Thus, it is of practical value to simplify analytic and calculating methods of electromagnetic propagation and scattering on the periodic notched planar structure.

PERTURBATION OBJECTS FOR MICROWAVE FIELD STRENGTH MEASUREMENT

GU MAOZHANG

1986, 4(2):  158-164. 

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Resonant frequency shift of a cavity perturbed by spherical, prolate or oblate objects with dielectric materials or materials having a permeability different from μ₀ is presented. Metal perturbators could be considered as perturbatorg with|ε_r|→ ∞ and|μ_r|→0.

MEASURING THE TERRAIN SCATTERING COEFFICIENT WITH AN X-BAND GROUND-BASED SCATTEROMETER

XU SAIGING, ZHU WEIZHONG, YU SHUNDI

1986, 4(2):  165-170. 

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A method for measurment of terrain scattering coefficient is presented. In addition, a calculable method of effective illumination area for microwave scatterometer is discussed.

THE EXPERIMENTAL DETERMINATION OF THE GAIN CHARACTERISTIC CURVES OF ELECTRON MULTIPLIER

HOU XIAOYUAN, YU MINREN, WANG XUN

1986, 4(2):  171-174. 

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The gain vs electron energy characteristic curves of an electron multiplier have been measured in an electron spectrometer by changing the pass energy of its energy analyser to introduce the Ni₃p photoelectrons with different energy into the electron multiplier. It is found that the gain character varies with different multiplier voltages. The effect of this character On the measurement of AES peak-to-peak heights has been investigated.

EFFECT OF SOLID PARTICLES ON RHEOLOGICAL PROPERTIES IN CONCENTRATED SUSPENSIONS

ZHU WANZHANG

1986, 4(2):  175-181. 

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The effects of the volume fraction of solid particles, φ, the ratio of particle diameters, R, and the volume fraction of small particles in solid amount, φ_s, on rheological properties in concentrated suspensions were studied. Commercial ammonium perchlorate and aluminium powder were used as dispersed phase, and a polyether diol as continuous phase. In bimodal dispersed systems the viscosity of the systems is minimum at φ_s=0.30, and decreases as R decreases. The influence of small particles is shown to be very important in the pseudoplastic behavior of concentrated suspensions. With the increase of small particle content or the decrease of particle diameter ratio in suspension, the pseudoplastio extent of the system increases. The effects of φ and φ_s on system become stronger when non-spherical particles exist in suspension. In bimodal system with wide distribution of spherical particle size the effect of φ on the pseudoplasticity of the system is less than that in the system with narrow distribution.

AUTOMATIC SENSITIVE METHANE SEMICONDUCTOR WARNER ON MINER'S LAMP

WANG CHUNGJI, LI PEIDE, ZHANG SHUXIAN, HAN ZHONGYI, LI XIAOYUN, SUN YUXIANG

1986, 4(2):  182-185. 

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The CH₄ sensitive semiconductor material was prepared from a high purity uonstoichiometrio n-type β-SnO_2-x. A ceramic CH₄ sensor was made from In, Pd-doped SnO_2-x. The CH₄ sensor was mounted on a miner's lamp, and the miner's lamp battary was used as the power supply. A new automatic methane warner has thus been developed and tested in some mines. When the CH₄ sensor on the warner contacts with CH₄ of over 1% concentration, the lamp automatically gives successive flash warnings.

TWO IMPROVED ALGORITHMS OF CONSTRUCTING RSNF

LIU YONGCAI

1986, 4(2):  186-188. 

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J. E. Savage has developed an algorithm of constructing Boolean function's ring-siim normal form (RSNF),which is based on disjunction normal form (DNF). In this paper the complexity of Savage's algorithm ≤ 2·3_n-2_n-1 is obtained (the upper bound can be achieved) and two direct algorithms of constructing BSNF are given. The complexities of the two direct algorithms are the same, being 3_n -2ⁿ.