Table of Content

31 March 1983, Volume 1 Issue 1

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Articles

THE IMPORTANCE OF APPLIED SCIENCE FOR THE MODERNIZATION OF SCIENCE AND TECHNOLOGY IN CHINA

C. K. JEN

1983, 1(1):  1-4. 

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For the immediate aim of modernization, it is expedient for China to accelerate research and development in applied science on the basis of fundamental science originated in advanced countries. This approach will make it possible to efficiently optimize the advancement of modern technology in all aspects. On the other hand, in the long run China has to cultivate the growth of fundamental science on her own to catch up with or even overtake the modern technology of advanced nations.

A METHOD OF ITERATION IN THE OPTIMIZATION OF THE FUNCTIONALS

HUA LOOKENG, XIA DAOXING

1983, 1(1):  5-8. 

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Let F be a sufficiently smooth functional on an open set in a Banach space. The equationcan
F' (x₀) =0.

EQUILIBRIA AMONG CERTAIN DEEP-LEVEL TRAPS IN GaAs

ZOU YUANXI

1983, 1(1):  9-16. 

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A proportionality relationship has recently been found to exist between the density of the EL2 electron trap in VPE GaAs and the As/Ga ratio in the gas phase, and also between the ratio[C]/[EL2] and n_300K for VPE GaAs grown in N², where C is a new electron trap found by Ozeki et al. These relationships have led us to the supposition that C and EL2 might be (VGa) 2 and AsGaVGaVAs respectively, and the equilibrium among AsAs (VGa) 2 and AgGaVGaVAs has been named as the C-EL2 or C-A equilibrium.

ON SOME THEORETICAL LIMITATIONS OF MICROWAVE RESISTIVE MIXER

GU MOLIN

1983, 1(1):  17-24. 

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This paper derives by means of scattering matrix the theoretical limits of convertion loss and noise figure of idealized microwave resistive mixer with its image frequency, sum frequency and the other harmonics under different terminating load conditions (that is, all of chem are resistively termined, reaotioely terminated, or some of them are resistively terminated, reaotively terminated and other combinations). Attempts have heen made to illustrate some basic pyhsical concepts involved under partial and total energy recovery and non-recovery working conditions.The results are summarized in table 1. It is found that under image matched conditions it is possible to have a single-sideband noise figure of less than 3dB, and that the ultimate noise figure is 3.92 dB with all ports matched.

A NUMERICAL SCHEME FOR NONLINEAR KLEIN-GORDON EQUATIONS

GUO BENYU, LUIS VAZQUEZ

1983, 1(1):  25-32. 

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The finite difference method is useful in mathematical physics for solving the nonlinear wave equations. The key problem involved is how to deal with the nonlinear term.
In this paper, numerical scheme for nonlinear Klein-Gordon equation is developed and an error estimation is established with the technique of[2-5].

AN IMPROVEMENT AND EXTENSION ON ROSENBROCK'S ALGORITHM FOR MINIMUM REALIZATION

ZHANG ZHONGJUN, HUA ZHAOLIN, WU XIOUJING, HUANG WUYANG

1983, 1(1):  33-42. 

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One of the fundamental problems in linear time-invariant multivariable system theory is to obtain minimum realization from a given transfer matrix. In this paper, Rosenbrock's algorithm for minimum realization is improved to reduce the order of the matrix polynomials of the transfer function matrix and to reduce the computing time. As the minimum realization so obtained is not in canonical form, the authors attempt to develop another algorithm to transform the first one into Luenberger's canonical form. Both algorithms are tested on DJS-130 computer.

MEASUREMENT OF SODIUM ACTIVITY IN DILUTED LIQUID SODIUM AMALGAM USING SOLID ELECTROLYTE CELL Na|β-Al₂O₃|Na_xHg_1-x

SUN CHENGWEN, KUO CHUKUN, CAO JIADI

1983, 1(1):  43-48. 

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Sodium activity coefficient in liquid sodium amalgam has been determined by measuring the emf of the solid electrolyte cell Na|β-Al₂O₃|Na_xHg_1-x, for x=0.00001 to 0.055 at temperatures from 303.15 K to 383.15 K. The temperature dependence of the emf of the cells with various x values shows several small breaks located at ca. 318.15K, 333. 15K, 353.15 K and 370.85 K respectively. The discrepancies of the emf-temperature coefficients in different temperature-intervals decrease gradually with decreasing x values. Experimental parameter eguations determined for (1) emf of the cells (E)， (2) sodium activity coefficients in amalgams (γ_Na)， and (3) standard emf (E⁰) of the cell consisting of pure sodium and a hypothetical sodium amalgam with state extrapolated from a reference state at infinite dilution are as follows.

TRANSITION IN THE MELT OF TETRAFLUOROETHYLENE-PERFLUOROALKYL VINYL ETHER COPOLYMER

PAN DAOCHENG, XIA GENGLIN, SUN XIUYIN, SHI GUANYI, YUE JUNSHI, FU KEHONG, WANG LIHUA

1983, 1(1):  49-54. 

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A physical transition T_u in the melt of tetraftuoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) can be detected by torsional braid analysis technique. The crystalline morphologies of the melt-crystallized PFA. also show a significant dependence on the melt temperature round about the transition temperature T_u. When PFA is cooled and crystallized from a temperature in the range of T_u to Tm, the randomly arranged lamella will be obtained, when it is cooled from a temperature above T_u, the spherulitic morphology will be formed; and when it is cooled from a temperature within the transition temperature range T_u, the rodlike morphology will be obtained. The isothermal crystallization rate, measured by DSG, also has a distinct change above and below T_u. But differential scanning calorimetry measurement does not show an endothermic peak occurring at transition temperature interval, so the transition is attributed to the change of chain configuration with the increase of temperature.

THE ROLE OF CARBON IN Mn-Al-C PERMANENT-MAGNETIC ALLOYS

YANG CHUANZHENG, JIANG XIAOLONG, XU SHUNSHENG, QING ZHICHUN

1983, 1(1):  55-62. 

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The role of carbon in Mn-Al-C permanent-magnetic alloys was investigated by means of X-ray diffraction and other methods. The phases existing in Mn (72wt%) -Al (28wt%) and Mn-Al-0 (0.5~1.5%) alloys in cast, quenched (from 1150℃) and annealed (450° -650℃) states were determined. A small amount of β phase and Mn₃AlC precipitated in the alloys during high temperature annealing when the carbon content was higher than 1%. The addition of carbon made the formation of the highly-magnetic transtion phase τ easier with better stability, and decreased the eutectoid decomposition temperature up to about 70℃. Addition of carbon in Mn-Al alloy also changed the lattice constants of ε and τ phases. The lattice constant a became smaller and c larger in the tody-centered tetragonal phase τ with increasing amount of carbon, when the carbon content is>0.6%, which is the solubility limit of carbon in Mn-Al alloy. The lattice constant a approached a constant value while c continued to rise, when carbon is >1%, corresponding to the supersa-turation of carbon in Mn-Al alloy. When the supersaturation became too great and the metastable state was destroyed, lattice constant c had a trend to recover and became smaller. The trend of the variation of c/a ratio was the same as that of c. In comparison with the binary Mn-Al alloy, the ternary Mn-Al-lC alloy had a higher degree of long range order in both ε and τ phases. The contribution of carbon to the magnetic property of the alloy is discussed on the basis of the uniaxial strain, the degree of long range order, the dispersed particles of Mn₃AlC and crystal imperfections.

APPLICATIONS OF SCANNING ELECTRON MICROSCOPE IN EXAMINATION OF INFRARED DETECTOR MATERIALS

CHEN BOLIANG, YU JINBI, DIN SUZHEN, WANG XINGFENG

1983, 1(1):  63-70. 

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In this paper some results from examining infrared detector materials using scanning electron microscope of type DX-3A (manufactured in China) are reported. Te-rich inclusions in HgCdTe and metal inclusions in PbSnTe have been detected successfully, the smallest dimension of which is ten micrometers. Precision determination of compositions of Hg_1-xCd_xTe and Pb_1-xSn_xTe crystals is made, and inho-mogeneity of △x/x>2% in a crystal wafer can be discriminated. The thieknees of hetero-epitaxial layer of PbSnTe-PbTe can also be determined.

MESFET/SOS IC FABRICATION AND DEVICE CHARACTERISTICS AT LIQUID NITROGEN TEMPERATURE

SHEN GUOXIONG, ZHAO PENGCHENG

1983, 1(1):  71-76. 

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In this paper, fabrication of a MESFET/SOS microwave differential amplifier is described. The full ion implantation technique is applied. Only three masks are needed to simplify the processes.
The D. C. and microwave properties for MESFET/SOS devices at room temperature and liquid nitrogen temperature (i. e. 77K) are also investigated.

A PRELIMINARY STUDY OF THE MATHEMATICAL THEORY OF PULSATION IN THE TRADITIONAL CHINESE MEDICAL SCIENCE

CHEN HUIJIANG, ZHU XUEYAN

1983, 1(1):  77-82. 

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In this paper, we modify the Windkessel model for blood circulation, and attempt to derive a mathematical theory for the cardiovascular system. It is shown that pulse graph can be used to study the said system, and may serve as a scientific background for the pulse theory of the traditional Chinese medical science.

INFINITESIMAL BACKLUND TRANSFORMATIONS AND SYMMETRIES OF NONLINEAR σ MODEL

TU GUIZHANG

1983, 1(1):  83-85. 

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An infinite number of symmetries of the nonlinear σ model are obtained and an explicit formula relating these symmetries with conserved densities is given.

ON MEASUREMENT OF SINGLE MODE FIBER PARAMETERS BY OBSERVATION OF FAR-FIELD RADIATION PATTERN

ZHANG YILONG, WANG ZIHUA, HUANG JUNHUA

1983, 1(1):  86-88. 

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This paper describes measurement of single mode fiber parameters by observation of far-field radiation pattern which is received by a vidicon and displayed on a monitor, while light intensity distribution of the far-field pattern is obtained by selected singleline scanning. V-value is determined directly by the ratio of sin θ₀ and sinθ_0.5 from the light intensity distribution. Typical experimental results are given.

MATHEMATICAL MODEL AND COMPUTER CALCULATIONS FOR THE NC CUTTING CAMS

XU JLNSHENG, XIE LIANGCHEN, TANG ZHANJI

1983, 1(1):  89-91. 

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In order to further raise the precision of cams processing by NO linear cutting technique, this article establishes a certain mathematical model and computer algorithm.
The algorithm thus obtained can be used to find out a precise locus of the moving molybdenum filament on the cutting machine to eliminate errors and raise the processing precision. This algorithm can also be applied to other work.

ON PROBLEMS OF GLOBAL OPTIMIZATION WITH ADAPTIVE CHANGE OF DOMAIN

ZHENG QUAN

1983, 1(1):  92-94. 

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In this paper, problems of global optimization with adaptive change of domain are considered. A new algorithm model of changed domains is suggested. Convergence theorem and optimality conditions are given and the connection of changed domains and global minimum values is discussed. The algorithm proves to be useful in finding global minimum of unconstrained and constrained optimization problems.