Table of Content

20 January 1996, Volume 32 Issue 1

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The Complex Linear Representations of the Quaternion Algebras

WANG Qili

1996, 32(1):  28-33. 

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Defined the complex linear representation of the generalized quaternion algebras over a field K, where K is a subfield of the complex number field C. We have determind completely these representations. Using this result, we gave a necessary and sufficient condition about the problem of the isomorphism of two generalized quaternion algebras.

The Role of Neutral Wind in Spread-F of Low and Mid-latitudes

Xie Hong,Liu Binsha,Xiao Zuo

1996, 32(1):  78-88. 

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Collisinal Rayleigh-Tailor instability in the ionospheric F region of low and mid-latitudes is discussed. Emphasis is put on the effects of thebackground neutral wind to the growth rate of the instability. A set of equations governing the R-T instability in this region is established with electric field and neutral wind included and the linear growth rate is deduced. The results show that the growth rate decreases as increasing latitude. For latitudes higher than 30 degree, normal neutral wind alone can no longer make the growth rate keeping positive values even under most favorable conditions, unless there is an eastward electric field. This indicates that the electric field may take an important role in local R-T instability evolution in mid-latitudes. Seasonal variations of the growth rate is also discussed using certain electron density profile model.

A Radio Astronomical Method of Searching Near-earth Asteroids

LUO Xianhan,ZHANG Jian,WANG Shujuan

1996, 32(1):  61-68. 

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Along with the rare event that the Comet SL-9 impact Jupiter was confirmed by observations, the task of searching near-earth asteroids and relative comets is obtaining more and more attention. Therefore, first of all, in view of the radiation tendency of cool and dark celestial bodies and detection limit of telescope, we point out the potential advantage of radio astronomical method for the task. Then, on the basis of predicted technical index of the 65m multi-waveband radio telescope, we discuss the feasibility of using beam switching method to detect the radio radiation of near-earth asteroids which can be very weak down to about 1 mJy. Also through the analysis of relative data of united observations, we introduce the basic steps of determining the direction, distance,velocity and size of the asteroids. Finally, we discuss the probability of themethod as mentioned above to be used for other astronomical objects.

A Parameterized Model for the Influence of Vegetation on the Moisture-heat Exchange at Near-ground Layer

LIU Shuhua

1996, 32(1):  69-77. 

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Advances a parameterized modelto study the influence of vegetation on the moisture-heat exchange at near-ground layer. With this model, the moisture-heat exchange between earth surface and atmosphere is studied under conditionsof different vegetation and soil moisture regime. The results show that the simulation states of temperature, moisture, radiation and energy balance are reasonable, and thus, this parameterized model is capable of using to study mesoscale meteorological modeling, climate modeling and environmental ecology.

Finite Element Method for Variational Inequalities with Discontinuous Coefficients

FENG Hui

1996, 32(1):  21-27. 

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The singularity of the solution of variational inequalities with coeffi-cients that are discontinuous across the interface is investigated, a prior estimate is obtained. We also design a net shape of the finite elements around the singular points of the solution. By means of this net,we prove that the approximate solution has the same convergence rateas that without singularity.

Evaluation on Justice in Grading Compositions of Enrollment Exams with EQQ Chart

ZHANG Daokui,SUN Shanze

1996, 32(1):  1-7. 

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It present a method for evaluation on justice in grading compositions of enrollment exams and discuss its statistical model. We discovered the distributions of grades of compositions and grades of other questions are similar in Chinese exams. There is a linear correlation between qauntiles of two distribution fuctions. The MLE's of parameters of the linear correlation are asymptotic normal. Finally we presented the EQQ Chart for evaluati on on justice in grading compositions.

Large Sample Properties of MLE of the Distribution Function with Incomplete Data

LIU Liping

1996, 32(1):  8-20. 

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In 1974 Turnbull proposed the nonparametric MLE of the distribution function with incomplete data which may be censored either from above or below. This estimat or is also self-consistent. When the data are grouped, we showed that the distribution function of interest and the distribution functions of the two censoring variables satisfy an equation system. By studying the uniqueness of the solution of this equation system, we proved the strong consistency of the Turnbull estimator. We also proved the asymptotic normality and the law of the iterated logarithm, and have given the matrix representation of the asymptotic covariance matrix and the accurate upper bounds of the convergence rate in the law of the iterated logarithm.

On the Oscillation and Nonoscillation for a Class of Nonlinear Differential Equations

LIU Zhengrong,YU Yuanhong

1996, 32(1):  34-39. 

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Sufficient conditions have been obtained for oscillation and nonoscil-lation of solutions of a class of nonlihear differential equations with piecewise constant arguments, which generalize some results of the literature.

Aharonov-Bohm Effect of a Variable Frequency Isotropic Oscillator Perturbed by an Inverse Square Potential

QIAN Shangwu,HUANG Bowen,GU Zhiyu

1996, 32(1):  40-44. 

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The dynamical system discussed by this paper is a variable frequency isotropic oscillator perturbed by an inverse square potential. This paper gives the expression of the propagator of the Aharonov-Bohm(AB) effect for such a dynamical system. Furthermore, this paper gives the expression of wave function for the particular case of constant frequency.

A New Approach to Probe the Interactions between C₆₀ and Non-Alkali-Metals

ZHAO Wenbing,WU Junqiao,CHEN Jun,WU Ke,ZHANG Jinlong,LI Chuanyi,YIN Daole,GU Zhennan,ZHOU Xihuang,JIN Zhaoxia

1996, 32(1):  45-51. 

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By measuring the resistance in situ during the deposition of C₆₀ on ultrathin metal layers at UHV system, we find that the change of sample resistance is universal and it is very sensitive to the thickness of the precusor metal films and the characteristics of the employed metal materials. This sensitivity of resistance change in metal-C₆₀ multilayers (bilayers) may be related to the charge transfer of metal to C₆₀ and surface bonding effects, hence can be used as a newpossible approach to probe the interfacial interactions between C₆₀ and metals.

The Anticancerous Experimental Research of Medicine and Tea

ZHOU Yaqin,SONG Zengfu,MENG Zhaoxin,XIA Meiying,DIN Xiaoping,ZHOU Shiwu,CHEN Xiaobo,HU Shengzhi

1996, 32(1):  52-54. 

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The interaction of several medicines and chinese green tea with DNA was studied through measurements of EB fluorescent intensity, in order to understand their preventive effect of cancer and anticancerous effects. This new results have followed the previous work, which has been published in this journal in 1993.

The Phenomenological Models of Site-type Impurity Potential in Doped Trans-Polyacetylene

JIA Rongyi,YAN Ligen,WANG Demin

1996, 32(1):  55-60. 

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The effects of Site-type impurity potential which includes isotropic and anisotropic conditions on the electronic states in doped trans-polyacetylene have been calculated numerically by SSH model. For isotropic condition, the results have shown that the Site-type impurity potential can break down the symmetry of midgap state. In addition, changing the spacing of charged impurity ions to the chain only causes the variation of soliton state, however, the degree of localization of soliton is not changed at all. Further study has indicated that a marked variation in the electronic states of trans-PA is caused by the anisotropic impurity potential. In particular, when the magnitude of the anisotropic degree γ is larger than 2.5, the degree of localization for these soliton states decreases rapidly.

A Discussion of the Learning in a Simple Perceptron

GONG Zhonglin,HUANG Song

1996, 32(1):  89-95. 

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The effect of loop shape of the planar loop dipoles to the broad-band input impedance characteristics has been studied by use of an optimization method, the result indicates that the circle is the optimum shape. An example of constructing a parasitic array antenna with broad-band impedance characteristics by use of such an optimum shape dipole is given.

Photoemission of Na₂KSb Photocathode Stimulated by Ultrashortpulse Laser

LIU Yanwen,ZHANG Gengmin,LIU Weimin,WU Jinlei,XUE Zengquan,WU Quande

1996, 32(1):  96-102. 

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We report the study of Na₂KSb photocathode as high brillance electronic injector. We have measured the properties of the multiphoton photoelectron emission with ultra short pulse laser (the wavelength is 1.06 μm, the width of a pulse is 50 ps). It was two photons effect. We have also tudied photoelectron emission limit.

The Double-readout Trace-back Algorithm for Viterbi Decoder and Its Complementation in ASIC

SHENG Shimin,LIU Yue,JI Lijiu

1996, 32(1):  103-109. 

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A novel double-readout trace-back(DRTB) algorithm that used in Viterbi Decoderfor likelihood path series searching is developed by analyzing the rule of trace-back operation. It increases the throughput rate up to 4 times without any additonal hardware overhead. The structural ASIC design of surviving path memory unit (SMU) toward DRTB algorithm is described and it is applied in a Viterbi Decoder IC design. With being fabricated, the test results indicate that the DRTB algorithm and circuit design are successful as prediction.

Modular-tree: A Self-architecture Neural Network Architecture

CHEN Ke,YU Xiang,CHI Huisheng,YANG Liping

1996, 32(1):  110-119. 

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Presented a novel self-architecure modular neural network architecture, called modular-tree for supervised learning. In the architecture, any kind of feedforward neural networks can be employed as componenets and a modular neural network with the tree structure is generated automatically with a growing algorithm by partitioning input space recursively to avoid the problem of pre-determined structure. Due to the principle of divide-and-conquer used in the proposed architecture, the modular-tree can yield both a good performance and significantly fast training. The proposed architecture has been applied to several supervised learning tasks including both benchmark and real-world problems and achieved satisfactory results.

On Future Development of Geographic Science(GS)

MA Ainai

1996, 32(1):  120-129. 

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The crisis-ridden has done in the geography recently. For example, some Universities had renamed their Department of Geography which named Urban and Environmental Science, Land and Ocean Science, Resource and Environmental Science and so on. To be sure, Meteorology, Hydrology, Pedology, Qnaternary Geology, Land Science, Ecology, Environmemtal Science, Regional Economics and Sustainable Development Work have made parts or overall to cover Geography once by once. Even Historical Geography has been belonged to History. Geography has faced to disintegration. In the world, Europe and America, their geography leid particular stress on humanities. Some Universities close down the Department of Geography in the United States. The Preceding USSR, geography leid particular stress on nature which had influenced in our country deeply. Recently, Russian geography is going to find new way. For example, it is called constructional geography. Author deem to recognize an object of geographical science again with recent half century geographic developmental history to be necessary. The crisis- ridden also has brought an opportunity for us. This paper put forward a system of geographic science. The core of geographic science is “Man and Earth” relationship that is the“Man and Earth”System. An outline for this system is: 1.An object of GS and it's threshold of time and space This paragraph put forward a “Man and Earth”system which is an megalocomplex variations and open system. And separate geography three parts:ancient geography, historical geography and modern geographic science. 2.Ancient geography Human was controlled by nature phenomena. There is an ancient physical geographical system which including ancient geomorphology, Quaternary sedimentary, ancient pedologic geography, ancient biologic geography, ancient hydrologic geography, ancient climatology and ancient humanity. 3.Historical geography Since human was controlled by nature phenomena to become that human has contred nature phenomena. There is a historic geographic system which including historical synthetic geography, historical partial geography and historical regional geography and so on. 4.Modern geographical science system There are three levels. In the top is geographical basic science which including theoretical geography, partial and regional geography. The second level is geographical technology which including observational geography, surveying geography, experimental geography, metrological geography and geographic information science. In the bottom level is geographic engineering which including environment engineering, ecosystem, land management, population controlled, urbans and towns construction, regional development, disasters monitoring and the globe change monitoring. 5.Sustainable development(SD) system for flourshing together of “Man and Earth" There are agriculture and mariculture, light and heavy industry, and the third and information industry in the sustainable development.