Table of Content

20 January 1997, Volume 33 Issue 1

Previous Issue    Next Issue

Initial-Regular Oblique Derivative Problems for Nonlinear Parabolic Systems of Several Second Order Equations with Measurable Coefficients

WEN Guochun

1997, 33(1):  1-11. 

Asbtract ( )  

Related Articles | Metrics

The initial-regular oblique derivative problem for nonlinear parabolic systems of several second order complex equations with measurable coefficients in a multiply connected domain is discussed. Firstly, the author is a priori estimates of solutions for the above initial-boundary value problem with some conditions, afterwards by using the above estimates of solutions and the method of parameter extension, the existence of solutions for the above problem is proved.

Attribute Recognition Theoretical Model with Application

CHENG Qiansheng

1997, 33(1):  12-20. 

Asbtract ( )  

Related Articles | Metrics

Based on the concepts of attribute measure space and ordered partition class, the attribute recognition criterion is presented, attribute recognition theoretical model is established and applied to atmospheric quality assessment.

On Common Borel Directions of a Meromorphic Function and its Derivatives

CHUANG Chitai

1997, 33(1):  21-31. 

Asbtract ( )  

Related Articles | Metrics

Since Valiron proposed the problem of studying the common Borel directions of an entire or meromorphic function and its derivative, it had been studied by various authors such as Cartwright, Rauch, Chuang, Milloux, Chang, Yang and Hu. Recently Zhu also studies this problem. His main result is that a Borel direction of order lambda of a meromorphic function f(z) of finite positive order lambda is a Borel direction of order lambda of one at least of the three functions f'(z), (zf(z))' and ((z+1) f(z))'. In the proof he skillfully applies a theorem of Chuang on the growth of meromorphic functions and a theorem of Yang on the value-distribution of such functions. In the present paper we study the problem in a different way. Also basing upon these two theorems, we shall show that, under certain conditions, a given direction argz=θ₀ is a common Borel direction of order lambda of a meromorphic function f(z) of finite positive order lambda and all its successive derivatives f(m)(z) (m=1,2,…).

The Variational Distance for Asymptotic Distribution of Extreme Values (Modulo One)

QI Yongcheng

1997, 33(1):  32-41. 

Asbtract ( )  

Related Articles | Metrics

Let { X_j, j≥ 1} be a sequence of independant and identically distributed random variables. Let U(0,1) be a random variable distributed uniformly over (0,1) and ξ(x) be the fractional part of x. under certain conditions, ξ(max_1≤j≤nX_j) converges in distribution to U(0,1). This paper is devoted to estimation of the total variation sup_B∈B |P( ξ(max_1≤j≤nX_j)∈ B) - P(U(0,1)∈B)|。

Oscillation of Second Order Delay Difference Equations

YU Wensheng,LIN Shizhong,YU Yuanhong

1997, 33(1):  42-48. 

Asbtract ( )  

Related Articles | Metrics

Some new oscillation criteria for the second order nonlinear delaydifference equations Delta²y_n+P_nf(y_n-k)=0 are established. Here Deltay_n=y_n+1-y_n is difference operator, k is nonnegative integers, {P_n} is a sequence of nonnegative real numbers and f is continuous on R=(-infinity,infinity).

A Theoretical Research of Thermoelectric Power of Bi_2-xPb_xSr₂CaCu₂O_8+δ

YANG Xiaoqiang,ZHANG Liyuan

1997, 33(1):  49-52. 

Asbtract ( )  

Related Articles | Metrics

A theoretical research of thermoelectric power of Bi_2-xPb_xSr₂CaCu₂O_8+δ is done with the local pair thermoelectric power theory, and the results are consistent with the experiment. It is argued that the high-T_C superconductor, which is considered as a two-component system (nearly local negative U center subsystem and itinerant carriers subsystem), goes through a delocalized process when temperature decreases. Below a certain temperature, it tends to become superconducting.

Study on Sea Ice Remote Sensing with GMS Real-Time Infrared Channel Data

LI Wanbiao,ZHU Yuanjing,ZHAO Bolin

1997, 33(1):  53-61. 

Asbtract ( )  

Related Articles | Metrics

By using GMS-4 infrared brightness temperature and visible albedo data from Jan. to Feb. In 1994, methods of extracting sea ice parameters are developed and digital remote sensing pictures are obtained in Liaodong Bay. Based on the difference in physical properties between ice and water, a criterion distinguishing ice from water is set up and the threshold value of brightness is achieved. Ice thickness has been calculated according to the relationship between ice thickness and brightness by thephysical and statistical methods. The retrieval distributions of ice thickness are in good agreement with observations. The results show that a precision of ice identification and thickness retrieval is 78.25% and 65.97%, respectively.

Numerical Simulation of the Heat and Moisture Fluxes at Different Underlying Surface

LIU Shuhua

1997, 33(1):  62-72. 

Asbtract ( )  

Related Articles | Metrics

A numerical model is developed for simulating microclimate of bare soil, which is incorporated in one-dimensional boundary layer model. The sensitivity of the scheme to several soil physical parameters is evaluated. Numerical simulated results indicate that the most important soil characteristic parameter is the soil moisture, and next is the surface albedo, which regulates the heat balance and the strength of the fluxes of heat and moisture between thermosphere and the ground.

On the Causes of the 1993 Excessively Heavy Rainfall in USA

LI Xianzhi

1997, 33(1):  73-76. 

Asbtract ( )  

Related Articles | Metrics

Most of the American scientists are inclined to believe that the 1993 excessively heavy rainfall in USA is closely connected with EL Nino. But in this paper, by using meteorological observations and statistical results, it is proposed and certified that the main causes are the thermal influence of Sargasso Sea and the dynamical effect of the interhemispheric macro-synoptic system.

Separation of Different Scale Weather System in Heavy Rain and Their Interaction

ZHANG Hong,YANG Fuquan

1997, 33(1):  77-84. 

Asbtract ( )  

Related Articles | Metrics

The horizontal filtering technique is employed to separate meso-scale field from large scale field for a case of heavy precipation over Yangzi river occurred on 1-5 July 1991. The northern large-scale jet stream has a maximum velocity center exceeding 50 m/s on 200 hPa. Meanwhile, the southern jet stream corresponding to the large-scale precipitation area, has a maximum wind velocity on 500 hPa exceeding 20 m/s. It is also found that when the meso-scale center of high field and wind vector fieldare nearly the same, a heavy rain center is always located. Finally, the contribution term to the development of meso-scale low on 700 hPa at different levels are evaluated. It is found that 700 hPa term is the biggest, while 500 hPa and 200 hPa terms have the same magnitude. They have same variation step.

The Deriving of Cloud Motion Winds from IR Images of GMS

BAI Jie,WANG Hongqing,TAO Zuyu

1997, 33(1):  85-92. 

Asbtract ( )  

Related Articles | Metrics

Global observation of atmospheric wind fields are potentially the most impotent data in the analysis for numerical prediction. This paper describes the computer image recognition technique of deriving cloud motion winds (CMW) from the IR images of GMS. The first step in the processing is objects classification analysis in an image segment corresponding to an area of 32×32 IR pixels. In this paper, we use direct classification and K-means algorithm to distinguish the high cloud, meddle cloud, low cloud and earth's surface. At the second step we adopt IR cross-correlation technique in the calculation of CMW, the correlation values between the brightness of the template window and the search window are calculated in the search area of the later time image, a cross-correlation coefficient surface is obtained. For the determination of CMW height, the average weight value of IR brightness temperature of object cloud is compared with the climatic statistic vertical temperature profile in this season, and CMW height, i.e. high cloud, meddle cloud or low cloud, is determined.

Stability of Electron Circular Orbit in an Ion-channel Electron Cyclotron Maser

LIU Pukun

1997, 33(1):  93-96. 

Asbtract ( )  

Related Articles | Metrics

Three-dimensional perturbed motion of relativistic electron in an ion-channel electron cyclotron maser(ICECM) is investigated by using the fluid theory. The result shows that, under the action of electromagnetic wave, the initial helix orbit of electron moving along the ion-channel is perturbed and its projection in the transverse plane is not a standard circle. But the transverse motion of electron is still kept within a ring with a not large thickness and is not divergent so long as the parameters are chosen to avoid two special singularities. So, the electron ' s orbit can be thought to be stable, and the electrons can be transported regularly in the interaction space.

Barium Ultrafine Particles in Barium Oxide Crystal

ZHANG Gengmin,WU Quande

1997, 33(1):  97-103. 

Asbtract ( )  

Related Articles | Metrics

The excess barium, which is indispensable to a well-activated oxide-cathode, can exist in two forms in BaO crystal: oxygen vacancies and barium ultrafine particles (UFPs). When the density of the oxygen vacancies exceeds the critical value, the formation and the growth of the barium UFPs take place. Some experimental results related to BaO crystal with excess barium are interpreted, and the role of barium ultrafine particles is accentuated. The optical absorption of BaO around photonenergy 2.0eV is attributed to barium UFPs embedded in BaO, and the low work function of the oxide cathode is considered to arise from the presence of oxygen vacancies. The physical origin of the photoemission from the oxide cathode bears a resemblance to that of the photoemission from Ag-O-Cs cathode in visible and infrared region.

Preservation of Elementary Properties of the Theory of Modules when Their Underlying Ring is Limited to an Ideal of the Ring

WANG Hanpin

1997, 33(1):  104-109. 

Asbtract ( )  

Related Articles | Metrics

Let R be an ideal of a ring with unity, M_R be a R-module. Then M also can be viewed as a I-module. It is proved that some elementary properties of the theory of modules, such as purity, pure-injectivity, elementary equivalent, elementary embedding etc. are reserved between M_R and M_I.

Protocol Specification Based on CSP

SUN Yong,YANG Hongji

1997, 33(1):  110-122. 

Asbtract ( )  

Related Articles | Metrics

When specifying and designing computer network protocols, it is convenient to use an abstract synchronous communication mechanism. In practice, however, asynchronous communication mechanisms cannot be avoided. This paper presents a formal approach, based on Hoare's Communicating Sequential Processes (CSP) and some theoretical results, to the specification and design of protocols which ensure the correctness of the protocols regardless of the communication mechanism used in implementation. The Alternating Bit (AB) protocol is used to illustrate our results.

Insurance and Actuarial Science

WU Lan,YANG Jingping,HU Dekun

1997, 33(1):  123-136. 

Asbtract ( )  

Related Articles | Metrics

Modern insurance science is a composition of insurance theory, economics, mathematics, statistics and computer science. It will take a very important part in the economic development in China. The present article is concerned mainly with the actuarial science in modern insurance. At first, the history and the current situation of insurance are reviewed generally. Then our paper introduces the key parts in the actuarial insurance, including the life actuarial science with survival analysis and thecasualty actuarial science with credibility theory and risk theory. And some hot lines in related fields listed afterward. This part consists of the researching of insurance strategies and insurance techniques in China. Finally the article emphasized the importance of training and bringing up more actuaries for the growing up of Chinese insurance. In our opinion, modern insurance, as an important part of the marketing economy activities, is a compensation method to decrease the uncertain loss and also is a kind of commodity being exchanged in market. Under the condition of fair competition, the statistical computing and analysis of insurance transaction, which have not been worked on for a long time in China, are important foundations for the insurance operation and with powerful competence. There are some basic preparations to do, such as the day-by-day collecting of the insurance transaction data and the modeling of the insurance operation. Under the circumstances, actuary can develop the new types and fields of insured risk, give the financial analysis reports of the portfolios and predict the future financial management. As the actuarial science itself, we are interested in the following subjects: a) Estimating the loss distribution of non-life insurance and designing new kinds of policies; b) Planning the pension system for any kind of company, society and group; c) Using credibility theory to do rate-making in Chinese insurance market; d) Applying the risk theory to evaluate the financial management of insurance companies.

Insurance and Actuarial Science

WU Lan,YANG Jingping,HU Dekun

1997, 33(1):  123-136. 

Asbtract ( )  

Related Articles | Metrics

Modern insurance science is a composition of insurance theory, economics, mathematics, statistics and computer science. It will take a very important part in the economic development in China. The present article is concerned mainly with the actuarial science in modern insurance. At first, the history and the current situation of insurance are reviewed generally. Then our paper introduces the key parts in the actuarial insurance, including the life actuarial science with survival analysis and thecasualty actuarial science with credibility theory and risk theory. And some hot lines in related fields listed afterward.This part consists of the researching of insurance strategies and insurance techniques in China. Finally the article emphasized the importance of training and bringing up more actuaries for the growing up of Chinese insurance.In our opinion, modern insurance, as an important part of the marketing economy activities, is a compensation method to decrease the uncertain loss and also is a kind of commodity being exchanged in market. Under the condition of fair competition, the statistical computing and analysis of insurance transaction, which have not been worked on for a long time in China, are important foundations for the insurance operation and with powerful competence. There are some basic preparations to do, such as the day-by-day collecting of the insurance transaction data and the modeling of the insurance operation. Under the circumstances, actuary can develop the new types and fields of insured risk, give the financial analysis reports of the portfolios and predict the future financial management. As the actuarial science itself, we are interested in the following subjects: a) Estimating the loss distribution of non-life insurance and designing new kinds of policies; b) Planning the pension system for any kind of company, society and group; c) Using credibility theory to do rate-making in Chinese insurance market; d) Applying the risk theory to evaluate the financial management of insurance companies.