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    30 September 1996, Volume 14 Issue 3
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    Articles
    THE SCIENTIFIC DEFINITION AND APPLICATIONS OF LINEAR THERMAL EXPANSION COEFFICIENT OF MATERIAL
    LU RONGSHENG, FEI YETAI
    1996, 14(3):  253-258. 
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    The linear thermal expansion coefficient of material defined as the change in length suffered by a unit length of the special rod when its temperature is changed by 1℃ is really the thermal deformation coefficient of its length, so there exists an error of theory in the coefficient. This paper details these problems and puts forward a new scientific definition of the linear thermal expansion coefficient.
    PREPARATION AND CHARACTERIZATION OF TWO-DIMENSIONAL DOMAINS IN THE MIXED MONOLAYER FILMS
    WU HAIMING, XIAO SHOUJUN, WEI YU
    1996, 14(3):  259-264. 
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    Two-dimensional domain structures were prepared in the mixed monolayer films composed of fatty acid and 5, 10, 15-triphenyl -20-(4-dl-α-phenylalanylamindo) phenyl porphyrin(TPPP) by the mixed Langmuir-Blodgett technique. Through atomic force microscopy studies, we observed the fatty acid domains in the liquid-condensed phase for the conditions of long alkyl chain. By shortening the length of the hydrocarbon chain, TPPP domains in the liquid-expanded phase were observed. A brief discussion about the practical usage of this kind of structures was presented in this paper.
    MODEL OF PETRI NET AND ITS ANALYSIS OF REPAIRABLE SYSTEMS
    JIANG CHANGJUN, SHU SONGGUT
    1996, 14(3):  265-270. 
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    The Petri net has been used for the establishment and analysis of many practical systems, but the reliability problem of the system is often neglected. In fact, there exist the phenomena of troubles and repairs in practical systems. This paper introduces the reliability theory into the Petri net and establishes the Petri net model of the repairable system. The analysis method of the system model is presented, and a simulation for a productive system is given for illustrating the necessity of this work.
    STABILITY ANALYSIS AND RESPONSE CONTROL OF A FLEXIBLE ROTOR SYSTEM WITH ELECTROMAGNETIC FORCES
    ZHU MEILING, ZHAO CHUNSHENG, WANG FENGQUAN
    1996, 14(3):  271-278. 
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    The shafts of many modern rotating machines have usually been designed into supercritical flexible shafts. The vibrations induced by various perturbations during operation may cause large amplitude displacements relative to the support structure, and/or give rise to system instability, even to major accidents. An important remedy is to place an active control force in the proper location of the shaft. The stability analysis and response control of a rotor system with electromagnetic forces are investigated in this paper. The formulas of magnetic forces with respect to the displacement of the journal center and coil current are derived. The eigenfunctions to describe the dynamic characteristic of electromagnetic forces are presented to analyze the stability of the system. The minimum setting values of controller and the relationship between the locations of the assigned sensor and actuator are given by using the perturbation method and the Rouge-Hurwitz theory on condition that the stability is satisfied. The experiment of active vibration control of a rotor system of unbalance mass has been made using an olectromagnetic actuator. The results illustrate the efficiency of the present analysis and the effect of vibration reduction.
    STRAIN-STRENGTH TIME MODEL(SSTM)
    XU RENPING, DUN XIANJIAN
    1996, 14(3):  279-284. 
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    In this paper, the strain-strength time model(SSTM) is presented on the basis of the random wave of strain-load and strain-strength and the changeability of reliability with time.Examples are given,showing the calculation methods of strain reliability with time by means of the P-ε-N curve of the Manson-Coffin formula and the three-parameter power function.
    OPTIMAL ANALYSIS OF THE TEMPERATURE DIFFERENCE FOR HEAT-TRANSFER OF A CARNOT ENGINE
    TIAN XINQUAN, YAN ZIJUN
    1996, 14(3):  285-290. 
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    Using the theory of finite-time thermodynamics, the optimal temperature difference for heat-transfer of an endoreversible Carnot engine is analysed,and several plans for the choice of optimal temperature difference are discussed.Then, the effects of other irreversibilities, except thermal resistance, on the optimal temperature difference are analysed. Some more instructive new conclusions for the practical heat engine are obtained.
    THE EFFECTS OF HEAT RESISTANCE, HEAT LEAK, AND INTERNAL IRREVERSIBILITY ON THE PERFORMANCE OF THE REFRIGERATION PLANTS
    CHEN LINGEN, SUN FENGRUI
    1996, 14(3):  291-294. 
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    On the basis of the endoreversible refrigeration cycle model which considers only the irreversibility of heat resistance between working fluid and heat reservoirs, this paper presents a new irreversible refrigerator model by add a constant parameter to represent the loss of heat leak, and a constant coefficient to represent the internal irreversibilities, such as friction, turbulence, non-equilibrium and so on. The relation between the optimal rate of refrigeration(ROR) and the coefficient of performance (COP) of the model is derived, the maximum COP and the corresponding ROR are obtained, and the effects of heat resistance, heat leak and internal irreversibility on the performance of the refrigeration plant are analysed.
    COMPUTATION AND ANALYSIS OF RCS AND CREEPING WAVE MODES FOR A LOSSY MATERIAL COATED CYLINDER
    WANG XILIANG, FENG YONGCHENG, SHEN LIYIN, QING XIANMING
    1996, 14(3):  295-299. 
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    The RCS of a lossy material coated conducting cylinder has been computed and analysed, and a numerical method for computing creeping wave propagation constants and amplitudes on the surface of the cylinder is presented in the paper. On the surface of a conducting cylinder,the defect of low precision for creeping wave propagation constants obtained by Keller's formulas at low frequency is overcome by the method. Propagation constants and amplitudes of creeping wave current modes on the surface of a lossy material coated conducting cylinder.which are hardly obtained by GTD, have been resolved.

    THE FORMING THEORIES AND CAD OF THE ROTARY CUTTING BURS
    LIU HURAN
    1996, 14(3):  300-306. 
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    A study is made of the forming theories and the computer aided design of the rotary cutting burs,for the purpose of finding the movement of the machining system and the corresponding sectional curvature of the groove conveniently.
    DEVELOPMENT OF MODEL ZC-20B FAST TESTER FOR EVALUATINC CAST IRON LIQUID QUALITY
    LI DAYONG, ZHANG YUTONG, ZHANG PEIHONG
    1996, 14(3):  307-312. 
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    The Model ZC-20B tester developed wish the principle of thermal analysis and the technology of microcomputer has the advantages of high testing speed, high precision, low cost and convenient use. The tester can be used in front of the cupola and electrical furnace to test cast iron liquid quality and the testing results include 20 parameters such as characteristic temperature points on the cooling curve, chemical composition, mechanical property, eutectic cells number,nodular graphite grade and so on. In the paper,the general structure of the tester,the design method of the sampling holder, the data acquizition system and the mathematic models are introduced.
    DEEP LEVELS IN STRAINED SiGe ALLOY
    QIAO HAO, XU ZHIZHONG, ZHANG KAIMING
    1996, 14(3):  313-317. 
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    Deep levels of vacancy and substitutional impurity atoms in a strained Si1-xGex alloy grown on Si, Ge and alloy substrates are investigated. The band structures of the strained alloy are calculated by using the empirical tight-binding method. The method of Green's function has been used to calculate the defect levels. The results show that the triply-degenerate p-like T2 level of the defect in bulk Si or Ge splits into two levels due to the strain. Owing to the strain, the valence band maximum of the alloy shifts upward, hence some deep levels in the bulk might transform to resonant ones.
    THE DOMAIN ACTIVITIES DURING THE MAGNETIZATION REVERSAL PROCESS IN SMALL PERMALLOY FILM STRIPES
    YU JINYUE, YE WEICHEN, SONG BAIQUAN, ZHOU YONG, ZHANG HONG
    1996, 14(3):  318-324. 
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    By the Bitter pattern technique and the energy analysis method, we systematically studied the character and variations of domain structures during the magnetization reversal process along the hard-axis direction of a 40 nm NiFe film stripe. It shows that the Barkhausen jumps in the element are the result of the irreversible domain processes, involving domain wall mergence, closure domain transitions, and wall-state transitions.
    AN ANLYTICAL CURRENT TRANSPORTATION MODEL FOR POLYSILICON EMITTER BIPOLAR TRANSISTOR OPERATION AT LOW TEMPERATURES
    WU JIN, WEI TONGLI
    1996, 14(3):  325-331. 
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    The technology and structure of the polysilicon emitter is one of the important bases of modern advance silicon bipolar transistors operation for low temperatures. As for samll dimensional polysilicon bipolar transistors, and nuder the approximations of neglecting the recombination in the crystal emitter and base region, a nonlinear one dimension analytical model for emitter injecting alection current density Jn and for base injecting hole current density Jps are proposed based on the combining effects of tunneling and recombination mechanism in the polysilicon and single crystal interface. The model is available for low temperature operation and different biased conditions, providing a quick, convenient and high precision tool for D. C. and A. C. proformances simulation and can be used as an important supplement to the multi-dimensional numerical modeling In guiding the optimization design for low temperature devices.
    CALCULATION AND ANALYSIS OF THE IONIZED FRACTION AND THE EFFECTIVE MAJORITY-CARRIER CONCENTRATION IN SILICON AT LOW TEMPERATURES
    XIAO ZHIXIONG, ZRENG JIANG, WEI TONGLI
    1996, 14(3):  332-338. 
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    In this paper, from the consideration of the bandgap narrowing effect resulting from heavily doping, a mathematic model for the ionized fraction and the effective majority-carrier concentration which is applicable from 77 to 300K is proposed. The obtained results are in accord with the existing calculative data at low doping concentrations; and at high doping concentrations, it has solved a problem which was not solved in the previous references:the quantitative calculation of the impurity ionized fraction increasing with the increase of the doping concentration.
    MICROANALYSIS OF CONSTITUTE PHASES IN ZnOBi2O3-Sb2O3-BaO VARISTOR CERAMIC SYSTEMS
    CMEN ZHIXIONG, HUANG ZHOUHE, SHI BIN, FU GANG
    1996, 14(3):  339-344. 
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    The miorostructure of varistor ceramics based on ZnO-Bi2O3-Sb2O3BaO systems has been investigated by XRD and EPMA techniques. A new grain boundary phase in which trace Zn tobe, dissolved is found besides the known ZnO,Bizoa and Zn2.33Sb0.67O4 crystal phases, it is the BaSb2O6 crystal phase. This phase in grain forms mixes with the dispersed Bi2O3 grain boundary phase. With the increase in the amount of barium additive, it increases in amount and grows in grain size, while Zn2.33Sb0.67O4 decreases in amount. It is also found that the long life stability of the varistor ceramics under a loaded voltage is improved due to the change of the composition and the microstructure in the intergranular layer.
    STUDY OF DIELECTRIC CHERENKOV MASER
    WU JIANQIANG, XIONG CAIDONG, LIU SHENGGANG
    1996, 14(3):  345-352. 
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    Making use of the self-consistent linear field theory, the three-dimensional perturbation of electrons affected by the perturbed electromagnetic fields is generally discussed. The interactions of wave to the two conventional relativistic electron beams in the dielectric Cherenkov maser, i.e., annular electron beam and solid electron beam, are analyzed in detail. The dispersion equations and the wave growth rates corresponding to the two relativistic electron beams are derived.The effects of the radii of the two electron beams on the wave growth rates are calculated, and the discussions are presented.
    STUDIES OF THE GRASS-GREEN MOLYBDATE CONVERSION FILM ON STAINLESS STEEL
    HAN KEPING, FANG JINGLI, LIU QIN
    1996, 14(3):  353-357. 
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    A grass-green conversion film was formed on stainless steel with the cathodic electcodeposition method from molybdate solution. This film displayed good thermostability. The results of XPS and AES analysis showed that the thickness of the film was 173nm and Mo existed as Mo(VI) on the surface of the film, but as Mo(VI) and Mo(IV) in the niternal layer of the film. The relative atomic percent contents (A.C.%) of the film obtained from the elemental composition constant region of the profile curved by AES were O 52.8%, Mo 30.4%,P 12.5% and Fe 4.3%respectively. The cyclevoltammetric oxidation peak also showed that the Mo (IV) existed in the internal layer of the film.
    STUDIES ON THE ENZYME BIOSENSOR FOR EVALUATING FISH FRESHNESS
    PENG TUZHI, YANG LIJU, LI HUIPING, SHEN LIANQING
    1996, 14(3):  358-363. 
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    A sensitive hypoxanthine biosensor was constructed using xanthine oxidase and a plate platinum electrode. The enzyme was conveniently immobilized on a silk protein membrane by glutaraldehyde. The electrode detected the hydrogen peroxide released during the enzymatic reaction. The electrode used very small quantity of enzyme and its detection limit of hypoxanthine was 1×10-7 mol/L When applied to the determination of the freshness of fish, the results obtained agreed well with those obtained by the traditional methods——the method of total volatile basic nitrogen and the method of total colonies of microbe.
    NEURAL NETWORKS AND CHELATING SPECTROPHOTOMETRY FOR SIMULTANEOUS DETERMINATION OF FIFTEEN RARE EARTH ELEMENTS
    LI ZHILIANG, YU BANMEI, LIU YAFENG, SAKAI M., SHI YUEMING, LI MENGLONG
    1996, 14(3):  364-368. 
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    Neural networks(NN) and multiwavelength spectroscopy were investigated systematically for multicomponent analysis. In this paper, neural networks and chelating spectrophotometry were applied to multivariate calibration and spectral resolution. The neural networks(NN) were trained by ordinary propagation(OBP) and the modified propagation(MBP). The chelating photometric reagent was selected as tribromochlorophosphanazo(TBCPA). The proposed sensitive spectrophotometry combined with the propagation neural networks (BPNN) was used for the simultaneous determination of 15 rare earth elements with good results. The relative standard divrations were leas than and about equal to 5%, RSD ≤ 5%, in general. It was shown that the neural networks can be used as a novel powerful chemometric technique for multicomponent analysis, especially for multivariate calibration and spectral resolution.
    OPPENHEIM-LIKE INEQUALITIES FOR M-MATRICES
    HUANG TINZHU
    1996, 14(3):  369-371. 
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    In this paper, the Oppenheim-like inequality for the general M-ma-trices is obtained, i.e., det(A·B) ≥ (Πi=1nbii) det A for general M-matrices A and B of order n.
    THE REVISED E BALAS DECISION-MAKING METHOD
    WU SHAOJI, DU WENZHONG
    1996, 14(3):  372-374. 
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    In this paper, on the basis of the E Balas decision-making method,we put forward a kind of revised method. Compared with the original method,the new method is able to converge fabler. It proves to be a practical method as shown in the investment system.
    ARTIFICIAL NEURAL NETWORK METHOD APPLIED TO PREDICTION OF MULTIPLE PROPERTIES OF V PTC MATERIALS
    LU WENCONG, YAN LICHENG, CHEN NIANYI
    1996, 14(3):  375-378. 
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    The Artificial Neural Network is a new type of information processing system based on modelling the neural system structure of the human brain. It can be used to extract useful information from the experimental data of V-PTC materials. The nonlinear relationships between the multiple properties and the affecting factors including technical conditions and compositions are available by using the B-P algorithm. The results of computer-aided prediction of the multiple properties of V-PTC materials have been proved to be consistent with the experimental values.
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Bimonthly, Founded in 1983
Editor-in-Chief:Wang Tingyun
ISSN 0255-8297
CN 31-1404/N